Loutfi S. Aboussouan, MD

A 76-year-old man whose history included abdominal aortic aneurysm repair, bilateral femoral artery bypass for popliteal artery aneurysm, hypertension, and peptic ulcer disease was admitted to a community hospital with pleuritic chest pain and shortness of breath. Two days earlier, he had undergone repair of a ventral hernia.

At the time of that admission, he reported no fever, chills, night sweats, cough, or history of heart or lung disease. His vital signs were normal, and physical examination had revealed no apparent respiratory distress, no jugular venous distention, normal heart sounds, and no pedal edema; however, decreased air entry was noted in the right lung base. Initial serum levels of troponin and N-terminal pro-B-type natriuretic peptide were normal.

At that time, computed tomographic angiography of the chest showed segmental pulmonary emboli in the left upper and right lower lobes of the lungs and right pleural effusion. Transthoracic echocardiography showed normal atrial and ventricular sizes with no right or left ventricular systolic dysfunction and a left ventricular ejection fraction of 59%.

Treatment with intravenous heparin was started, and the patient was transferred to our hospital.

PLEURAL EFFUSION AND PULMONARY EMBOLISM

1. Which of the following is true about pleural effusion?

• It is rarely, if ever, associated with pulmonary embolism
• Most patients with pleural effusion due to pulmonary embolism do not have pleuritic chest pain
• Pulmonary embolism should be excluded in all cases of pleural effusion without a clear cause

Pulmonary embolism should be excluded in all cases of pleural effusion that do not have a clear cause. As for the other answer choices:

• Pulmonary embolism is the fourth leading cause of pleural effusion in the United States, after heart failure, pneumonia, and malignancy.¹
• About 75% of patients who develop pleural effusion in the setting of pulmonary embolism complain of pleuritic chest pain on the side of the effusion.² Most effusions are unilateral, small, and usually exudative.³

EVALUATION BEGINS: RESULTS OF THORACENTESIS

Our patient continued to receive intravenous heparin.

He underwent thoracentesis on hospital day 3, and 1,000 mL of turbid sanguineous pleural fluid was removed. Analysis of the fluid showed pH 7.27, white blood cell count 3.797 × 10⁹/L with 80% neutrophils, and lactate dehydrogenase (LDH) concentration 736 U/L (a ratio of pleural fluid LDH to a concurrent serum LDH > 0.6 is suggestive of an exudate); the fluid was also sent for culture and cytology. Thoracentesis was terminated early due to cough, and follow-up chest radiography showed a moderate-sized pneumothorax.

Computed tomography (CT) of the chest at this time showed a small wedge-shaped area of lung consolidation in the right lower lobe (also seen on CT done 1 day before admission to our hospital), with an intrinsic air-fluid level suggesting a focal infarct or lung abscess, now obscured by adjacent consolidation and atelectasis. In the interval since the previous CT, the multiloculated right pleural effusion had increased in size (Figure 1).

THE NEXT STEP

2. What is the most appropriate next step for this patient?

• Consult an interventional radiologist for chest tube placement
• Start empiric antibiotic therapy and ask an interventional radiologist to place a chest tube
• Start empiric antibiotic therapy, withhold anticoagulation, and consult a thoracic surgeon
• Start empiric antibiotic therapy and consult a thoracic surgeon while continuing anticoagulation

The most appropriate next step is to start empiric antibiotic therapy and consult a thoracic surgeon while continuing anticoagulation.

In this patient, it is appropriate to initiate antibiotics empirically on the basis of his significant pleural loculations, a wedge-shaped consolidation, and 80% neutrophils in the pleural fluid, all of which suggest infection. The unmasking of a wedge-shaped consolidation after thoracentesis, with a previously noted air-fluid level and an interval increase in multiloculated pleural fluid, raises suspicion of a necrotic infection that may have ruptured into the pleural space, a possible lung infarct, or a malignancy. Hence, simply placing a chest tube may not be enough.

Blood in the pleural fluid does not necessitate withholding anticoagulation unless the bleeding is heavy. A pleural fluid hematocrit greater than 50% of the peripheral blood hematocrit suggests hemothorax and is an indication to withhold anticoagulation.¹ Our patient’s pleural fluid was qualitatively sanguineous but not frankly bloody, and therefore we judged that it was not necessary to stop his heparin.

HOW DOES PULMONARY INFARCTION PRESENT CLINICALLY?

3. Which of the following statements about pulmonary infarction is incorrect?

• Cavitation and infarction are more common with larger emboli
• Cavitation occurs in fewer than 10% of pulmonary infarctions
• Lung abscess develops in more than 50% of pulmonary infarctions
• Pulmonary thromboembolism is the most common cause of pulmonary infarction

Lung abscess develops in far fewer than 50% of cases of pulmonary infarction. The rest of the statements are correct.

Cavitation complicates about 4% to 7% of infarctions and is more common when the infarction is 4 cm or greater in diameter.⁴ These cavities are usually single and predominantly on the right side in the apical or posterior segment of the upper lobe or the apical segment of the right lower lobe, as in our patient.^5–8 CT demonstrating scalloped inner margins and cross-cavity band shadows suggests a cavitary pulmonary infarction.^9,10

Infection and abscess in pulmonary infarction are poorly understood but have been linked to larger infarctions, coexistent congestion or atelectasis, and dental or oropharyngeal infection. In an early series of 550 cases of pulmonary infarction, 23 patients (4.2%) developed lung abscess and 6 (1.1%) developed empyema.¹¹ The mean time to cavitation for an infected pulmonary infarction has been reported to be 18 days.¹²

A reversed halo sign, generally described as a focal, rounded area of ground-glass opacity surrounded by a nearly complete ring of consolidation, has been reported to be more frequent with pulmonary infarction than with other diseases, especially when in the lower lobes.¹³

CASE CONTINUED: THORACOSCOPY

A cardiothoracic surgeon was consulted, intravenous heparin was discontinued, an inferior vena cava filter was placed, and the patient underwent video-assisted thoracoscopy.

Purulent fluid was noted on the lateral aspect of right lower lobe; this appeared to be the ruptured cavitary lesion functioning like an uncontrolled bronchopleural fistula. Two chest tubes, sizes 32F and 28F, were placed after decortication, resection of the lung abscess, and closure of the bronchopleural fistula. No significant air leak was noted after resection of this segment of lung.

Pathologic study showed acute organizing pneumonia with abscess formation; no malignant cells or granulomas were seen (Figure 2). Pleural fluid cultures grew Streptococcus intermedius, while the tissue culture was negative for any growth, including acid-fast bacilli and fungi.

On 3 different occasions, both chest tubes were shortened, backed out 2 cm, and resecured with sutures and pins, and Heimlich valves were applied before the patient was discharged.

Intravenous piperacillin-tazobactam was started on the fifth hospital day. On discharge, the patient was advised to continue this treatment for 3 weeks at home.

The patient was receiving enoxaparin subcutaneously in prophylactic doses; 72 hours after the thorascopic procedure this was increased to therapeutic doses, continuing after discharge. Bridging to warfarin was not advised in view of his chest tubes.

Our patient appeared to have developed a right lower lobe infarction that cavitated and ruptured into the pleural space, causing a bronchopleural fistula with empyema after a recent pulmonary embolism. Other reported causes of pulmonary infarction in pulmonary embolism are malignancy and heavy clot burden,⁶ but these have not been confirmed in subsequent studies.⁵ Malignancy was ruled out by biopsy of the resected portion of the lung, and our patient did not have a history of heart failure. A clear cavity was not noted (because it ruptured into the pleura), but an air-fluid level was described in a wedge-shaped consolidation, suggesting infarction.

How common is pulmonary infarction after pulmonary embolism?

Pulmonary infarction occurs in few patients with pulmonary embolism.¹³ Since the lungs receive oxygen from the airways and have a dual blood supply from the pulmonary and bronchial arteries, they are not particularly vulnerable to ischemia. However, the reported incidence of pulmonary infarction in patients with pulmonary embolism has ranged from 10% to higher than 30%.^5,14,15

The reasons behind pulmonary infarction with complications after pulmonary embolism have varied in different case series in different eras. CT, biopsy, or autopsy studies reveal pulmonary infarction after pulmonary embolism to be more common than suspected by clinical symptoms.

In a Mayo Clinic series of 43 cases of pulmonary infarction diagnosed over a 6-year period by surgical lung biopsy, 18 (42%) of the patients had underlying pulmonary thromboembolism, which was the most common cause.¹⁶

4. Which statement about risk factors for pulmonary infarction in pulmonary embolism is incorrect?

• Heart failure may be a risk factor for pulmonary infarction
• Pulmonary hemorrhage is a risk factor for pulmonary infarction
• Pulmonary infarction is more common with more proximal sites of pulmonary embolism
• Collateral circulation may protect against pulmonary infarction

Infarction is more common with emboli that are distal rather than proximal.

Dalen et al¹⁵ suggested that after pulmonary embolism, pulmonary hemorrhage is an important contributor to the development of pulmonary infarction independent of the presence or absence of associated cardiac or pulmonary disease, but that the effect depends on the site of obstruction.

This idea was first proposed in 1913, when Karsner and Ghoreyeb¹⁷ showed that when pulmonary arteries are completely obstructed, the bronchial arteries take over, except when the embolism is present in a small branch of the pulmonary artery. This is because the physiologic anastomosis between the pulmonary artery and the bronchial arteries is located at the precapillary level of the pulmonary artery, and the bronchial circulation does not take over until the pulmonary arterial pressure in the area of the embolism drops to zero.

Using CT data, Kirchner et al⁵ confirmed that the risk of pulmonary infarction is higher if the obstruction is peripheral, ie, distal.

Using autopsy data, Tsao et al¹⁸ reported a higher risk of pulmonary infarction in embolic occlusion of pulmonary vessels less than 3 mm in diameter.

Collateral circulation has been shown to protect against pulmonary infarction. For example, Miniati et al¹⁴ showed that healthy young patients with pulmonary embolism were more prone to develop pulmonary infarction, probably because they had less efficient collateral systems in the peripheral lung fields. In lung transplant recipients, it has been shown that the risk of infarction decreased with development of collateral circulation.¹⁹

Dalen et al,¹⁵ however, attributed delayed resolution of pulmonary hemorrhage (as measured by resolution of infiltrate on chest radiography) to higher underlying pulmonary venous pressure in patients with heart failure and consequent pulmonary infarction. In comparison, healthy patients without cardiac or pulmonary disease have faster resolution of pulmonary hemorrhage when present, and less likelihood of pulmonary infarction (and death in submassive pulmonary embolism).

Data on the management of infected pulmonary infarction are limited. Mortality rates have been as high as 41% with noninfected and 73% with infected cavitary infarctions.⁴ Some authors have advocated early surgical resection in view of high rates of failure of medical treatment due to lack of blood supply within the cavity and continued risk of infection.

KEY POINTS

In patients with a recently diagnosed pulmonary embolism and concurrent symptoms of bacterial pneumonia, a diagnosis of cavitary pulmonary infarction should be considered.

Consolidations that are pleural-based with sharp, rounded margins and with focal areas of central hyperlucencies representing hemorrhage on the mediastinal windows on CT are more likely to represent a pulmonary infarct.²⁰

A 76-year-old man whose history included abdominal aortic aneurysm repair, bilateral femoral artery bypass for popliteal artery aneurysm, hypertension, and peptic ulcer disease was admitted to a community hospital with pleuritic chest pain and shortness of breath. Two days earlier, he had undergone repair of a ventral hernia.

At the time of that admission, he reported no fever, chills, night sweats, cough, or history of heart or lung disease. His vital signs were normal, and physical examination had revealed no apparent respiratory distress, no jugular venous distention, normal heart sounds, and no pedal edema; however, decreased air entry was noted in the right lung base. Initial serum levels of troponin and N-terminal pro-B-type natriuretic peptide were normal.

At that time, computed tomographic angiography of the chest showed segmental pulmonary emboli in the left upper and right lower lobes of the lungs and right pleural effusion. Transthoracic echocardiography showed normal atrial and ventricular sizes with no right or left ventricular systolic dysfunction and a left ventricular ejection fraction of 59%.

Treatment with intravenous heparin was started, and the patient was transferred to our hospital.

PLEURAL EFFUSION AND PULMONARY EMBOLISM

1. Which of the following is true about pleural effusion?

• It is rarely, if ever, associated with pulmonary embolism
• Most patients with pleural effusion due to pulmonary embolism do not have pleuritic chest pain
• Pulmonary embolism should be excluded in all cases of pleural effusion without a clear cause

Pulmonary embolism should be excluded in all cases of pleural effusion that do not have a clear cause. As for the other answer choices:

• Pulmonary embolism is the fourth leading cause of pleural effusion in the United States, after heart failure, pneumonia, and malignancy.¹
• About 75% of patients who develop pleural effusion in the setting of pulmonary embolism complain of pleuritic chest pain on the side of the effusion.² Most effusions are unilateral, small, and usually exudative.³

EVALUATION BEGINS: RESULTS OF THORACENTESIS

Our patient continued to receive intravenous heparin.

He underwent thoracentesis on hospital day 3, and 1,000 mL of turbid sanguineous pleural fluid was removed. Analysis of the fluid showed pH 7.27, white blood cell count 3.797 × 10⁹/L with 80% neutrophils, and lactate dehydrogenase (LDH) concentration 736 U/L (a ratio of pleural fluid LDH to a concurrent serum LDH > 0.6 is suggestive of an exudate); the fluid was also sent for culture and cytology. Thoracentesis was terminated early due to cough, and follow-up chest radiography showed a moderate-sized pneumothorax.

Computed tomography (CT) of the chest at this time showed a small wedge-shaped area of lung consolidation in the right lower lobe (also seen on CT done 1 day before admission to our hospital), with an intrinsic air-fluid level suggesting a focal infarct or lung abscess, now obscured by adjacent consolidation and atelectasis. In the interval since the previous CT, the multiloculated right pleural effusion had increased in size (Figure 1).

THE NEXT STEP

2. What is the most appropriate next step for this patient?

• Consult an interventional radiologist for chest tube placement
• Start empiric antibiotic therapy and ask an interventional radiologist to place a chest tube
• Start empiric antibiotic therapy, withhold anticoagulation, and consult a thoracic surgeon
• Start empiric antibiotic therapy and consult a thoracic surgeon while continuing anticoagulation

The most appropriate next step is to start empiric antibiotic therapy and consult a thoracic surgeon while continuing anticoagulation.

In this patient, it is appropriate to initiate antibiotics empirically on the basis of his significant pleural loculations, a wedge-shaped consolidation, and 80% neutrophils in the pleural fluid, all of which suggest infection. The unmasking of a wedge-shaped consolidation after thoracentesis, with a previously noted air-fluid level and an interval increase in multiloculated pleural fluid, raises suspicion of a necrotic infection that may have ruptured into the pleural space, a possible lung infarct, or a malignancy. Hence, simply placing a chest tube may not be enough.

Blood in the pleural fluid does not necessitate withholding anticoagulation unless the bleeding is heavy. A pleural fluid hematocrit greater than 50% of the peripheral blood hematocrit suggests hemothorax and is an indication to withhold anticoagulation.¹ Our patient’s pleural fluid was qualitatively sanguineous but not frankly bloody, and therefore we judged that it was not necessary to stop his heparin.

HOW DOES PULMONARY INFARCTION PRESENT CLINICALLY?

3. Which of the following statements about pulmonary infarction is incorrect?

• Cavitation and infarction are more common with larger emboli
• Cavitation occurs in fewer than 10% of pulmonary infarctions
• Lung abscess develops in more than 50% of pulmonary infarctions
• Pulmonary thromboembolism is the most common cause of pulmonary infarction

Lung abscess develops in far fewer than 50% of cases of pulmonary infarction. The rest of the statements are correct.

Cavitation complicates about 4% to 7% of infarctions and is more common when the infarction is 4 cm or greater in diameter.⁴ These cavities are usually single and predominantly on the right side in the apical or posterior segment of the upper lobe or the apical segment of the right lower lobe, as in our patient.^5–8 CT demonstrating scalloped inner margins and cross-cavity band shadows suggests a cavitary pulmonary infarction.^9,10

Infection and abscess in pulmonary infarction are poorly understood but have been linked to larger infarctions, coexistent congestion or atelectasis, and dental or oropharyngeal infection. In an early series of 550 cases of pulmonary infarction, 23 patients (4.2%) developed lung abscess and 6 (1.1%) developed empyema.¹¹ The mean time to cavitation for an infected pulmonary infarction has been reported to be 18 days.¹²

A reversed halo sign, generally described as a focal, rounded area of ground-glass opacity surrounded by a nearly complete ring of consolidation, has been reported to be more frequent with pulmonary infarction than with other diseases, especially when in the lower lobes.¹³

CASE CONTINUED: THORACOSCOPY

A cardiothoracic surgeon was consulted, intravenous heparin was discontinued, an inferior vena cava filter was placed, and the patient underwent video-assisted thoracoscopy.

Purulent fluid was noted on the lateral aspect of right lower lobe; this appeared to be the ruptured cavitary lesion functioning like an uncontrolled bronchopleural fistula. Two chest tubes, sizes 32F and 28F, were placed after decortication, resection of the lung abscess, and closure of the bronchopleural fistula. No significant air leak was noted after resection of this segment of lung.

Pathologic study showed acute organizing pneumonia with abscess formation; no malignant cells or granulomas were seen (Figure 2). Pleural fluid cultures grew Streptococcus intermedius, while the tissue culture was negative for any growth, including acid-fast bacilli and fungi.

On 3 different occasions, both chest tubes were shortened, backed out 2 cm, and resecured with sutures and pins, and Heimlich valves were applied before the patient was discharged.

Intravenous piperacillin-tazobactam was started on the fifth hospital day. On discharge, the patient was advised to continue this treatment for 3 weeks at home.

The patient was receiving enoxaparin subcutaneously in prophylactic doses; 72 hours after the thorascopic procedure this was increased to therapeutic doses, continuing after discharge. Bridging to warfarin was not advised in view of his chest tubes.

Our patient appeared to have developed a right lower lobe infarction that cavitated and ruptured into the pleural space, causing a bronchopleural fistula with empyema after a recent pulmonary embolism. Other reported causes of pulmonary infarction in pulmonary embolism are malignancy and heavy clot burden,⁶ but these have not been confirmed in subsequent studies.⁵ Malignancy was ruled out by biopsy of the resected portion of the lung, and our patient did not have a history of heart failure. A clear cavity was not noted (because it ruptured into the pleura), but an air-fluid level was described in a wedge-shaped consolidation, suggesting infarction.

How common is pulmonary infarction after pulmonary embolism?

Pulmonary infarction occurs in few patients with pulmonary embolism.¹³ Since the lungs receive oxygen from the airways and have a dual blood supply from the pulmonary and bronchial arteries, they are not particularly vulnerable to ischemia. However, the reported incidence of pulmonary infarction in patients with pulmonary embolism has ranged from 10% to higher than 30%.^5,14,15

The reasons behind pulmonary infarction with complications after pulmonary embolism have varied in different case series in different eras. CT, biopsy, or autopsy studies reveal pulmonary infarction after pulmonary embolism to be more common than suspected by clinical symptoms.

In a Mayo Clinic series of 43 cases of pulmonary infarction diagnosed over a 6-year period by surgical lung biopsy, 18 (42%) of the patients had underlying pulmonary thromboembolism, which was the most common cause.¹⁶

4. Which statement about risk factors for pulmonary infarction in pulmonary embolism is incorrect?

• Heart failure may be a risk factor for pulmonary infarction
• Pulmonary hemorrhage is a risk factor for pulmonary infarction
• Pulmonary infarction is more common with more proximal sites of pulmonary embolism
• Collateral circulation may protect against pulmonary infarction

Infarction is more common with emboli that are distal rather than proximal.

Dalen et al¹⁵ suggested that after pulmonary embolism, pulmonary hemorrhage is an important contributor to the development of pulmonary infarction independent of the presence or absence of associated cardiac or pulmonary disease, but that the effect depends on the site of obstruction.

This idea was first proposed in 1913, when Karsner and Ghoreyeb¹⁷ showed that when pulmonary arteries are completely obstructed, the bronchial arteries take over, except when the embolism is present in a small branch of the pulmonary artery. This is because the physiologic anastomosis between the pulmonary artery and the bronchial arteries is located at the precapillary level of the pulmonary artery, and the bronchial circulation does not take over until the pulmonary arterial pressure in the area of the embolism drops to zero.

Using CT data, Kirchner et al⁵ confirmed that the risk of pulmonary infarction is higher if the obstruction is peripheral, ie, distal.

Using autopsy data, Tsao et al¹⁸ reported a higher risk of pulmonary infarction in embolic occlusion of pulmonary vessels less than 3 mm in diameter.

Collateral circulation has been shown to protect against pulmonary infarction. For example, Miniati et al¹⁴ showed that healthy young patients with pulmonary embolism were more prone to develop pulmonary infarction, probably because they had less efficient collateral systems in the peripheral lung fields. In lung transplant recipients, it has been shown that the risk of infarction decreased with development of collateral circulation.¹⁹

Dalen et al,¹⁵ however, attributed delayed resolution of pulmonary hemorrhage (as measured by resolution of infiltrate on chest radiography) to higher underlying pulmonary venous pressure in patients with heart failure and consequent pulmonary infarction. In comparison, healthy patients without cardiac or pulmonary disease have faster resolution of pulmonary hemorrhage when present, and less likelihood of pulmonary infarction (and death in submassive pulmonary embolism).

Data on the management of infected pulmonary infarction are limited. Mortality rates have been as high as 41% with noninfected and 73% with infected cavitary infarctions.⁴ Some authors have advocated early surgical resection in view of high rates of failure of medical treatment due to lack of blood supply within the cavity and continued risk of infection.

KEY POINTS

In patients with a recently diagnosed pulmonary embolism and concurrent symptoms of bacterial pneumonia, a diagnosis of cavitary pulmonary infarction should be considered.

Consolidations that are pleural-based with sharp, rounded margins and with focal areas of central hyperlucencies representing hemorrhage on the mediastinal windows on CT are more likely to represent a pulmonary infarct.²⁰

A 76-year-old man whose history included abdominal aortic aneurysm repair, bilateral femoral artery bypass for popliteal artery aneurysm, hypertension, and peptic ulcer disease was admitted to a community hospital with pleuritic chest pain and shortness of breath. Two days earlier, he had undergone repair of a ventral hernia.

At the time of that admission, he reported no fever, chills, night sweats, cough, or history of heart or lung disease. His vital signs were normal, and physical examination had revealed no apparent respiratory distress, no jugular venous distention, normal heart sounds, and no pedal edema; however, decreased air entry was noted in the right lung base. Initial serum levels of troponin and N-terminal pro-B-type natriuretic peptide were normal.

At that time, computed tomographic angiography of the chest showed segmental pulmonary emboli in the left upper and right lower lobes of the lungs and right pleural effusion. Transthoracic echocardiography showed normal atrial and ventricular sizes with no right or left ventricular systolic dysfunction and a left ventricular ejection fraction of 59%.

Treatment with intravenous heparin was started, and the patient was transferred to our hospital.

PLEURAL EFFUSION AND PULMONARY EMBOLISM

1. Which of the following is true about pleural effusion?

• It is rarely, if ever, associated with pulmonary embolism
• Most patients with pleural effusion due to pulmonary embolism do not have pleuritic chest pain
• Pulmonary embolism should be excluded in all cases of pleural effusion without a clear cause

Pulmonary embolism should be excluded in all cases of pleural effusion that do not have a clear cause. As for the other answer choices:

• Pulmonary embolism is the fourth leading cause of pleural effusion in the United States, after heart failure, pneumonia, and malignancy.¹
• About 75% of patients who develop pleural effusion in the setting of pulmonary embolism complain of pleuritic chest pain on the side of the effusion.² Most effusions are unilateral, small, and usually exudative.³

EVALUATION BEGINS: RESULTS OF THORACENTESIS

Our patient continued to receive intravenous heparin.

He underwent thoracentesis on hospital day 3, and 1,000 mL of turbid sanguineous pleural fluid was removed. Analysis of the fluid showed pH 7.27, white blood cell count 3.797 × 10⁹/L with 80% neutrophils, and lactate dehydrogenase (LDH) concentration 736 U/L (a ratio of pleural fluid LDH to a concurrent serum LDH > 0.6 is suggestive of an exudate); the fluid was also sent for culture and cytology. Thoracentesis was terminated early due to cough, and follow-up chest radiography showed a moderate-sized pneumothorax.

Computed tomography (CT) of the chest at this time showed a small wedge-shaped area of lung consolidation in the right lower lobe (also seen on CT done 1 day before admission to our hospital), with an intrinsic air-fluid level suggesting a focal infarct or lung abscess, now obscured by adjacent consolidation and atelectasis. In the interval since the previous CT, the multiloculated right pleural effusion had increased in size (Figure 1).

THE NEXT STEP

2. What is the most appropriate next step for this patient?

• Consult an interventional radiologist for chest tube placement
• Start empiric antibiotic therapy and ask an interventional radiologist to place a chest tube
• Start empiric antibiotic therapy, withhold anticoagulation, and consult a thoracic surgeon
• Start empiric antibiotic therapy and consult a thoracic surgeon while continuing anticoagulation

The most appropriate next step is to start empiric antibiotic therapy and consult a thoracic surgeon while continuing anticoagulation.

In this patient, it is appropriate to initiate antibiotics empirically on the basis of his significant pleural loculations, a wedge-shaped consolidation, and 80% neutrophils in the pleural fluid, all of which suggest infection. The unmasking of a wedge-shaped consolidation after thoracentesis, with a previously noted air-fluid level and an interval increase in multiloculated pleural fluid, raises suspicion of a necrotic infection that may have ruptured into the pleural space, a possible lung infarct, or a malignancy. Hence, simply placing a chest tube may not be enough.

Blood in the pleural fluid does not necessitate withholding anticoagulation unless the bleeding is heavy. A pleural fluid hematocrit greater than 50% of the peripheral blood hematocrit suggests hemothorax and is an indication to withhold anticoagulation.¹ Our patient’s pleural fluid was qualitatively sanguineous but not frankly bloody, and therefore we judged that it was not necessary to stop his heparin.

HOW DOES PULMONARY INFARCTION PRESENT CLINICALLY?

3. Which of the following statements about pulmonary infarction is incorrect?

• Cavitation and infarction are more common with larger emboli
• Cavitation occurs in fewer than 10% of pulmonary infarctions
• Lung abscess develops in more than 50% of pulmonary infarctions
• Pulmonary thromboembolism is the most common cause of pulmonary infarction

Lung abscess develops in far fewer than 50% of cases of pulmonary infarction. The rest of the statements are correct.

Cavitation complicates about 4% to 7% of infarctions and is more common when the infarction is 4 cm or greater in diameter.⁴ These cavities are usually single and predominantly on the right side in the apical or posterior segment of the upper lobe or the apical segment of the right lower lobe, as in our patient.^5–8 CT demonstrating scalloped inner margins and cross-cavity band shadows suggests a cavitary pulmonary infarction.^9,10

Infection and abscess in pulmonary infarction are poorly understood but have been linked to larger infarctions, coexistent congestion or atelectasis, and dental or oropharyngeal infection. In an early series of 550 cases of pulmonary infarction, 23 patients (4.2%) developed lung abscess and 6 (1.1%) developed empyema.¹¹ The mean time to cavitation for an infected pulmonary infarction has been reported to be 18 days.¹²

A reversed halo sign, generally described as a focal, rounded area of ground-glass opacity surrounded by a nearly complete ring of consolidation, has been reported to be more frequent with pulmonary infarction than with other diseases, especially when in the lower lobes.¹³

CASE CONTINUED: THORACOSCOPY

A cardiothoracic surgeon was consulted, intravenous heparin was discontinued, an inferior vena cava filter was placed, and the patient underwent video-assisted thoracoscopy.

Purulent fluid was noted on the lateral aspect of right lower lobe; this appeared to be the ruptured cavitary lesion functioning like an uncontrolled bronchopleural fistula. Two chest tubes, sizes 32F and 28F, were placed after decortication, resection of the lung abscess, and closure of the bronchopleural fistula. No significant air leak was noted after resection of this segment of lung.

Pathologic study showed acute organizing pneumonia with abscess formation; no malignant cells or granulomas were seen (Figure 2). Pleural fluid cultures grew Streptococcus intermedius, while the tissue culture was negative for any growth, including acid-fast bacilli and fungi.

On 3 different occasions, both chest tubes were shortened, backed out 2 cm, and resecured with sutures and pins, and Heimlich valves were applied before the patient was discharged.

Intravenous piperacillin-tazobactam was started on the fifth hospital day. On discharge, the patient was advised to continue this treatment for 3 weeks at home.

The patient was receiving enoxaparin subcutaneously in prophylactic doses; 72 hours after the thorascopic procedure this was increased to therapeutic doses, continuing after discharge. Bridging to warfarin was not advised in view of his chest tubes.

Our patient appeared to have developed a right lower lobe infarction that cavitated and ruptured into the pleural space, causing a bronchopleural fistula with empyema after a recent pulmonary embolism. Other reported causes of pulmonary infarction in pulmonary embolism are malignancy and heavy clot burden,⁶ but these have not been confirmed in subsequent studies.⁵ Malignancy was ruled out by biopsy of the resected portion of the lung, and our patient did not have a history of heart failure. A clear cavity was not noted (because it ruptured into the pleura), but an air-fluid level was described in a wedge-shaped consolidation, suggesting infarction.

How common is pulmonary infarction after pulmonary embolism?

Pulmonary infarction occurs in few patients with pulmonary embolism.¹³ Since the lungs receive oxygen from the airways and have a dual blood supply from the pulmonary and bronchial arteries, they are not particularly vulnerable to ischemia. However, the reported incidence of pulmonary infarction in patients with pulmonary embolism has ranged from 10% to higher than 30%.^5,14,15

The reasons behind pulmonary infarction with complications after pulmonary embolism have varied in different case series in different eras. CT, biopsy, or autopsy studies reveal pulmonary infarction after pulmonary embolism to be more common than suspected by clinical symptoms.

In a Mayo Clinic series of 43 cases of pulmonary infarction diagnosed over a 6-year period by surgical lung biopsy, 18 (42%) of the patients had underlying pulmonary thromboembolism, which was the most common cause.¹⁶

4. Which statement about risk factors for pulmonary infarction in pulmonary embolism is incorrect?

• Heart failure may be a risk factor for pulmonary infarction
• Pulmonary hemorrhage is a risk factor for pulmonary infarction
• Pulmonary infarction is more common with more proximal sites of pulmonary embolism
• Collateral circulation may protect against pulmonary infarction

Infarction is more common with emboli that are distal rather than proximal.

Dalen et al¹⁵ suggested that after pulmonary embolism, pulmonary hemorrhage is an important contributor to the development of pulmonary infarction independent of the presence or absence of associated cardiac or pulmonary disease, but that the effect depends on the site of obstruction.

This idea was first proposed in 1913, when Karsner and Ghoreyeb¹⁷ showed that when pulmonary arteries are completely obstructed, the bronchial arteries take over, except when the embolism is present in a small branch of the pulmonary artery. This is because the physiologic anastomosis between the pulmonary artery and the bronchial arteries is located at the precapillary level of the pulmonary artery, and the bronchial circulation does not take over until the pulmonary arterial pressure in the area of the embolism drops to zero.

Using CT data, Kirchner et al⁵ confirmed that the risk of pulmonary infarction is higher if the obstruction is peripheral, ie, distal.

Using autopsy data, Tsao et al¹⁸ reported a higher risk of pulmonary infarction in embolic occlusion of pulmonary vessels less than 3 mm in diameter.

Collateral circulation has been shown to protect against pulmonary infarction. For example, Miniati et al¹⁴ showed that healthy young patients with pulmonary embolism were more prone to develop pulmonary infarction, probably because they had less efficient collateral systems in the peripheral lung fields. In lung transplant recipients, it has been shown that the risk of infarction decreased with development of collateral circulation.¹⁹

Dalen et al,¹⁵ however, attributed delayed resolution of pulmonary hemorrhage (as measured by resolution of infiltrate on chest radiography) to higher underlying pulmonary venous pressure in patients with heart failure and consequent pulmonary infarction. In comparison, healthy patients without cardiac or pulmonary disease have faster resolution of pulmonary hemorrhage when present, and less likelihood of pulmonary infarction (and death in submassive pulmonary embolism).

Data on the management of infected pulmonary infarction are limited. Mortality rates have been as high as 41% with noninfected and 73% with infected cavitary infarctions.⁴ Some authors have advocated early surgical resection in view of high rates of failure of medical treatment due to lack of blood supply within the cavity and continued risk of infection.

KEY POINTS

In patients with a recently diagnosed pulmonary embolism and concurrent symptoms of bacterial pneumonia, a diagnosis of cavitary pulmonary infarction should be considered.

Consolidations that are pleural-based with sharp, rounded margins and with focal areas of central hyperlucencies representing hemorrhage on the mediastinal windows on CT are more likely to represent a pulmonary infarct.²⁰

In contrast to stable chronic obstructive pulmonary disease (COPD),¹ acute exacerbations of COPD pose special management challenges and can significantly increase the risk of morbidity and death and the cost of care.

This review addresses the definition and diagnosis of COPD exacerbations, disease burden and costs, etiology and pathogenesis, and management and prevention strategies.

DEFINITIONS ARE PROBLEMATIC

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) defines a COPD exacer­bation as “an acute event characterized by a worsening of the patient’s respiratory symptoms that is beyond normal day-to-day variations and leads to a change in medication.”² It further categorizes acute exacerbations by severity:

• Mild—treated with increased frequency of doses of existing medications
• Moderate—treated with corticosteroids or antibiotics, or both
• Severe—requires hospital utilization (either emergency room treatment or admission).

Although descriptive and useful for retrospective analyses, this current definition poses ambiguities for clinicians. Day-to-day variation in symptoms is not routinely assessed, so deviations from baseline may be difficult to detect. Although clinical tools are available for assessing symptoms in stable and exacerbated states (eg, the COPD assessment test³ and the Exacerbations of Chronic Pulmonary Disease Tool [EXACT]⁴), they have not been widely adopted in daily practice. Also, according to the current definition, the severity of an exacerbation can be classified only after the course of action is determined, so the severity is not helpful for forming a management strategy at bedside. In addition, physicians may have different thresholds for prescribing antibiotics and corticosteroids.

An earlier definition categorized a COPD exacerbation by the presence of its three cardinal symptoms (ie, increased shortness of breath, sputum volume, and purulence):

• Type I—all three symptoms present
• Type II—two symptoms present
• Type III—one symptom present, accompanied by at least one of the following: upper respiratory tract infection within the past 5 days, unexplained fever, increased wheezing or cough, or 20% increased respiratory rate or heart rate from baseline.

This older definition was successfully used in a prospective clinical trial to identify patients who benefited most from antibiotics for COPD exacerbations.⁵

COPD exacerbation: an acute worsening of respiratory symptoms

Despite these caveats regarding a definition, most clinicians agree on the clinical presentation of a patient with COPD exacerbation: ie, having some combination of shortness of breath, increased sputum volume, and purulence. By the same token, patients with COPD who present with symptoms not typical of an exacerbation should be evaluated for another diagnosis. For instance, Tillie-Leblond et al⁶ reported that 49 (25%) of 197 patients hospitalized with an “unexplained” exacerbation of COPD were eventually diagnosed with pulmonary embolism.

EXACERBATIONS ARE COSTLY

The care of patients with COPD places a great burden on the healthcare system. Using multiple national databases, Ford et al⁷ estimated that medical costs in the United States in 2010 attributable to COPD and its complications were $32.1 billion.

The largest component of direct healthcare costs of COPD is exacerbations and subsequent hospitalizations.⁸ Data from a predominantly Medicare population indicate that the annualized mean COPD-related cost for a patient with no exacerbations was $1,425, compared with $12,765 for a patient with severe exacerbations.⁹ The investigators estimated that reducing exacerbations from two or more to none could save $5,125 per patient per year.

EXACERBATIONS AFFECT HEALTH BEYOND THE EVENT

COPD exacerbations are associated with a faster decline in lung function,¹⁰ reduced quality of life,¹¹ and lost workdays.⁷ A single exacerbation may cause a decline in lung function and health status that may not return to baseline for several months, particularly if another exacerbation occurs within 6 months.^12,13 COPD exacerbations have also been linked to poor clinical outcomes, including death.

In a prospective study in 304 men with COPD followed for 5 years, those who had three or more COPD exacerbations annually were four times as likely to die than patients who did not have an exacerbation.¹⁴ Nevertheless, the relationship with mortality may not be causal: Brusselle pointed out in an editorial¹⁵ that established mortality predictors for COPD do not include exacerbations, and symptomatic patients with COPD without any history of exacerbations are at greater risk of death than those who are asymptomatic but at high risk for exacerbations.

INFECTION + INFLAMMATION = EXACERBATION

An acute COPD exacerbation can be viewed as an acute inflammatory event superimposed on chronic inflammation associated with COPD. Inflammation in the airways increases resistance to air flow with consequent air trapping. Increased resistance and elastic load due to air trapping place respiratory muscles at a mechanical disadvantage and increase the work of breathing.

Infection starts the process

Infections are thought to be the major instigators of COPD exacerbation

Infections, particularly bacterial and viral, are thought to be the major instigators of COPD exacerbation, although environmental factors such as air pollution may also play a role.¹⁶

Airway inflammation is markedly reduced when bacterial infection is eradicated. But if bacterial colonization continues, inflammatory markers remain elevated despite clinical resolution of the exacerbation.¹⁷ Desai et al¹⁸ found that patients with COPD and chronic bronchitis with bacterial colonization had a larger symptom burden than patients without colonization, even without an exacerbation.

Allergic profile increases risk

Although most studies indicate that infection is the main cause of exacerbations, clinicians should consider other mechanisms of inflammation on an individual basis. COPD exacerbations may be phenotyped by measuring inflammatory markers, perhaps as a starting point for tailored therapies.

Bafadhel et al¹⁹ studied 145 patients with COPD over the course of a year and recorded various biomarkers at baseline and during exacerbations. Exacerbations had an inflammatory profile that was predominantly bacterial in 37%, viral in 10%, and eosinophilic in 17%, and had limited changes in the inflammatory profile in 14%. The remaining episodes were combinations of categories. In another study,²⁰ multivariate analysis conducted in two cohorts with COPD found that patients who had an allergic phenotype had more respiratory symptoms and a higher likelihood of COPD exacerbations.

Frequent COPD exacerbations are increasingly recognized as being associated with an asthma-COPD overlap syndrome, consisting of symptoms of increased airflow variability and incompletely reversible airflow obstruction.²¹

Inflammation as a marker of frequent exacerbations

Evidence is accumulating that supports systemic inflammation as a marker of frequent exacerbations. The Copenhagen Heart Study tested for baseline plasma C-reactive protein, fibrinogen, and white blood cell count in 6,574 stable patients with COPD.²² After multivariable adjustment, they found a significantly higher likelihood of having a subsequent exacerbation in patients who had all three biomarkers elevated (odds ratio [OR] 3.7, 95% confidence interval [CI] 1.9–7.4), even in patients with milder COPD and those without previous exacerbations.

Past exacerbations predict risk

A history of exacerbation is the best predictor of future exacerbation

The Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints study²³ found that a history of acute COPD exacerbation was the single best predictor of future exacerbations. This risk factor remained stable over 3 years and was present across the severity of COPD, ie, patients at lower GOLD stages who had a history of frequent exacerbations were likely to have exacerbations during follow-up.

EXACERBATION INCREASES CARDIOVASCULAR RISK

COPD exacerbations increase the risk of cardiovascular events, particularly myocardial infarction.²⁴ During hospitalization for acute exacerbation of COPD, markers of myocardial injury and heart failure may be elevated and are a predictor of death.²⁵

Patel et al²⁶ measured arterial stiffness (aortic pulse wave velocity, a validated measure of cardiovascular risk) and cardiac biomarkers (troponin and N-terminal B-type natriuretic peptide) at baseline in 98 patients and longitudinally during and after a COPD exacerbation. In addition to increased levels of cardiac biomarkers, they found a significant rise in arterial stiffness during the exacerbation event without return to baseline levels over 35 days of follow-up. The arterial stiffness increase was related to airway inflammation as measured by sputum interleukin 6, particularly in patients with documented lower respiratory tract infection.

Retrospective analysis suggests a reduced all-cause mortality rate in COPD patients who are treated with beta-blockers.²⁷

Recommendation. We recommend that patients already taking a selective beta-blocker continue to do so during a COPD exacerbation.

OUTPATIENT MANAGEMENT

Treatment with a combination of a corticosteroid, antibiotic, and bronchodilator addresses the underlying pathophysiologic processes of an acute exacerbation: inflammation, infection, and airway trapping.

Short course of a corticosteroid improves outcomes

A single exacerbation may worsen health status for several months

A 10-day systemic course of a corticosteroid prescribed for COPD exacerbation before discharge from the emergency department was found to offer a small advantage over placebo for reducing treatment failure (unscheduled physician visits, return to emergency room for recurrent symptoms) and improving dyspnea scores and lung function.²⁸ Even just a 3-day course improved measures of respiration (forced expiratory volume in the first second of expiration [FEV₁] and arterial oxygenation) at days 3 and 10, and reduced treatment failures compared with placebo.²⁹

Corticosteroid prescription should not be taken lightly, because adverse effects are common. In a systematic review, one adverse effect (hyperglycemia, weight gain, or insomnia) occurred for every five people treated.³⁰

Identifying subgroups of patients most likely to benefit from corticosteroid treatment may be helpful. Corticosteroids may delay improvement in patients without eosinophilic inflammation and hasten recovery in those with more than 2% peripheral eosinophils.³¹ Siva et al³² found that limiting corticosteroids to patients with sputum eosinophilia reduced corticosteroid use and reduced severe exacerbations compared with standard care.³²

Recommendation. For an acute exacerbation, we prescribe a short course of corticosteroids (eg, prednisone 40 mg daily for 5 to 7 days). Tapering dosing is probably unnecessary because adrenal insufficiency is uncommon before 2 weeks of corticosteroid exposure. Clinicians should weigh the merits of tapering (reduced corticosteroid exposure) against patient inconvenience and difficulty following complicated instructions.

Antibiotics help, but exact strategy uncertain

Although antibiotic therapy is one of the three pillars of COPD exacerbation management, the optimal antimicrobial agent, duration of therapy, and which patients will benefit remain areas of controversy and research. Thus far, large trials have been unable to definitely show the superiority of one antibiotic over another.^33,34

A 1987 randomized controlled trial⁵ of antibiotic therapy in acute exacerbation of COPD found the greatest benefit to patients who had all three cardinal symptoms (ie, increased shortness of breath, sputum volume, and purulence), with less marked but still significant improvement in patients with two symptoms. In a 2012 multicenter trial³⁵ patients with mild to moderate COPD experiencing an exacerbation were treated with either combined amoxicillin and clavulanate or placebo if they had one of the three cardinal symptoms. The antibiotic group had a significantly higher clinical cure rate at days 9 to 11 (74.1% vs 59.9%) as well as a longer time until the next exacerbation (233 vs 160 days).

Recommendation. Optimal antibiotic management of COPD exacerbations may also depend on risk factors. For patients with at least two cardinal symptoms, we favor a scheme akin to one proposed for treating community-acquired pneumonia (Table 1).^16,36

INPATIENT MANAGEMENT

Corticosteroids improve outcomes

A Department of Veterans Affairs cooperative trial³⁷ randomized 271 patients hospitalized with COPD exacerbation to receive either corticosteroids (intravenous followed by oral) or placebo for either 2 weeks or 8 weeks. Corticosteroid recipients had lower rates of treatment failure at 30 and 90 days, defined as death from any cause, need for mechanical ventilation, readmission, or intensification of pharmacologic therapy. Corticosteroid therapy also reduced hospital length of stay and improved the rate of recovery. The longer corticosteroid course was associated with a higher rate of adverse effects.

Oral corticosteroids not inferior to intravenous

Using the same end point of treatment failure as the Veterans Affairs cooperative trial, deJong et al³⁸ demonstrated that prednisone 60 mg by mouth was not inferior to intravenous prednisone. Neither trial demonstrated a difference in mortality between corticosteroid use and placebo.

Short course of a corticosteroid not inferior to a long course

In 2013, the Reduction in the Use of Corticosteroids in Exacerbated COPD (REDUCE) trial³⁹ randomized 314 patients presenting with an acute COPD exacerbation (92% requiring hospital admission) to oral prednisone 40 mg daily for either 5 days or 14 days. They found that the short course was noninferior in preventing exacerbations over the ensuing 6 months in terms of death and the need for mechanical ventilation.

Recommendation. Our threshold for initiating systemic corticosteroid therapy is lower in hospitalized patients than in outpatients. We recommend the regimen of the REDUCE trial: prednisone 40 mg daily for 5 days.

Corticosteroids for patients on ventilatory support

Severe COPD exacerbations requiring admission to intensive care are a significant source of morbidity and mortality, and the strategy of corticosteroid treatment is still under investigation.

Intravenous corticosteroids are effective. A multicenter trial⁴⁰ in 354 patients requiring either invasive or noninvasive mechanical ventilation randomized them to treatment with either intravenous methylprednisolone (tapered) or placebo. Treatment was associated with fewer mechanical ventilation days and a lower rate of noninvasive ventilation failure.

Low-dose oral corticosteroids ineffective. In contrast, an open-label trial⁴¹ of patients requiring ventilatory support and randomized to either oral prednisone (1 mg/kg for up to 10 days) or usual care found no difference in intensive care length of stay or noninvasive ventilation failure. This study used the oral route and smaller doses, and its open-label design might have introduced bias.

Lower-dose steroids better than high-dose. A 2014 cohort study of 17,239 patients admitted to the ICU with acute exacerbations of COPD evaluated outcomes of treatment with high methylprednisolone dosages (> 240 mg per day) vs lower dosages, using propensity score matching.⁴² No mortality difference was found between the groups. The lower dosage group (median methylprednisolone dose 100 mg per day) had shorter hospital and intensive care unit stays, shorter duration of noninvasive positive pressure ventilation, less need for insulin therapy, and fewer fungal infections.

Antibiotics for hospitalized patients

Only scarce data are available on the use of antibiotics for patients hospitalized with COPD exacerbation. In a study of patients hospitalized with COPD exacerbations, adding doxycycline to corticosteroids led to better clinical success and cure rates at 10 days compared with placebo, but the primary end point of clinical success at 30 days was not different between the two groups.⁴³

BRONCHODILATORS: A MAINSTAY OF COPD TREATMENT

Bronchodilators are an important part of treatment of COPD exacerbations in inpatient and outpatient settings.

Nebulized beta-2 agonists are given every 1 to 4 hours. Albuterol at a 2.5-mg dose in each nebulization was found to be as effective as 5 mg for length of hospital stay and recovery of lung function in patients with an acute exacerbation of COPD.⁴⁴

Adding an anticholinergic may help. Nebulized anticholinergics can be given alone or combined with beta-2 agonists. Whether long-acting bronchodilators should be used to manage COPD patients hospitalized with an exacerbation requires further inquiry. In an observational study with historical controls, Drescher and colleagues⁴⁵ found cost savings and shorter hospital stays if tiotropium (a long-acting anticholinergic) was added to the respiratory care protocol, which also included formoterol (a long-acting beta-2 agonist).

OXYGEN: TITRATED APPROACH SAFER

Caution is needed to avoid hyperoxemic hypercapnia in patients on oxygen

Oxygen should be supplied during a COPD exacerbation to ensure adequate oxyhemoglobin saturation. Caution is needed to avoid hyperoxemic hypercapnia, particularly in patients with severe COPD and propensity to ventilatory failure. The routine administration of oxygen at high concentrations during a COPD exacerbation has been associated with a higher mortality rate than with a titrated oxygen approach.⁴⁶ Long-term oxygen treatment started at discharge or as outpatient therapy is associated with reduced hospital admissions and shorter hospital stays for acute exacerbations of COPD.⁴⁷

VENTILATION SUPPORT

Noninvasive positive-pressure ventilation is a useful adjunct to treatment of COPD exacerbations with evidence of ventilatory failure (ie, acute respiratory acidosis), helping to offset the work of breathing until respiratory system mechanics improve. Keenan et al⁴⁸ reviewed 15 randomized controlled trials, involving 636 patients, of noninvasive positive-pressure ventilation in the setting of COPD exacerbation. They concluded that noninvasive positive-pressure ventilation reduced the in-hospital mortality rate and length of stay compared with standard therapy. Noninvasive positive-pressure ventilation is most useful in patients with severe COPD exacerbations and acute respiratory acidosis (pH < 7.35).⁴⁹

Intubation and mechanical ventilation. Although no standards exist for determining which COPD exacerbations may be too severe for noninvasive positive-pressure ventilation, intubation is clearly indicated for impending respiratory failure or hemodynamic instability. Other factors to consider include the greater likelihood of noninvasive positive-pressure ventilation failure in patients with severe respiratory acidosis (pH < 7.25 is associated with a > 50% failure rate) and in those with no improvement in acidosis or respiratory rate during the first hour after initiation of noninvasive positive-pressure ventilation.⁵⁰

PREVENTING EXACERBATIONS

Recent data indicate that COPD exacerbations can often be prevented (Table 2).

Inhaled pharmacotherapy

Inhaled pharmacotherapeutic agents, singly or in combination, reduce the frequency of COPD exacerbations.

Combined long-acting beta-2 agonist and corticosteroid is better than single-agent therapy. In 2007, the Towards a Revolution in COPD Health (TORCH) trial⁵¹ evaluated outpatient therapy in more than 6,000 patients worldwide with either an inhaled long-acting beta-2 agonist (salmeterol), an inhaled corticosteroid (fluticasone), both drugs in combination, or placebo. Patients had baseline prebronchodilator FEV₁ of less than 60% and were followed for 3 years. No difference was found between the groups in the primary end point of deaths, but the annualized rate of moderate to severe exacerbations was reduced by 25% in the group that received combination therapy vs placebo. Combination therapy showed superior efficacy over individual drug therapy in preventing exacerbations. Treatment with the inhaled corticosteroid, whether alone or in combination with salmeterol, increased the risk of pneumonia.

A long-acting antimuscarinic agent is better than placebo. In 2008, the Understanding Potential Long-Term Impacts on Function With Tiotropium (UPLIFT) trial⁵² randomized nearly 6,000 patients with COPD and a postbronchodilator FEV₁ of less than 70% to placebo or tiotropium, a long-acting antimuscarinic agent. Tiotropium reduced the exacerbation rate by 14% compared with placebo and improved quality of life.

Antimuscarinics may be better than beta-2 agonists. Head-to-head comparisons suggest that long-acting antimuscarinic agents are preferable to long-acting beta-2 agonists for preventing COPD exacerbations.^53,54

Triple therapy: evidence is mixed. For patients with severe symptomatic COPD and frequent exacerbations, triple therapy with a combination of an inhaled long-acting antimuscarinic agent, an inhaled long-acting beta-2 agonist, and an inhaled corticosteroid has been suggested.

Data to support this practice are limited. In the Canadian Optimal Trial,⁵⁵ the rate of exacerbations was not different between tiotropium alone, tiotropium plus salmeterol, and triple therapy. However, the rate of hospitalization for severe exacerbation was lower with triple therapy than tiotropium alone. A large, retrospective cohort study also supported triple therapy by finding reduced mortality, hospitalizations, and need for oral corticosteroid bursts compared to combination therapy with an inhaled long-acting beta-2 agonist and an inhaled corticosteroid.⁵⁶

The drawback of triple therapy is an increased incidence of pneumonia associated with combined beta-2 agonist and corticosteroids, most likely due to the corticosteroid component.⁵¹ The risk appears to be higher for higher potency corticosteroids, eg, fluticasone.⁵⁷

In 2014, the Withdrawal of Inhaled Steroids During Optimised Bronchodilator Management (WISDOM) trial⁵⁸ randomized nearly 2,500 patients with a history of COPD exacerbation receiving triple therapy consisting of tiotropium, salmeterol, and inhaled fluticasone to either continue treatment or withdraw the corticosteroid for 3 months. The investigators defined an annualized exacerbation rate of 1.2 (ie, a 20% increase) as the upper limit of the confidence interval for an acceptable therapeutic margin of noninferiority. The study showed that the risk of moderate to severe exacerbations with combined tiotropium and salmeterol was noninferior to triple therapy.

Nevertheless, caution is advised when removing the corticosteroid component from triple therapy. The trial demonstrated a worsening in overall health status, some reduction in lung function, and a transient increase in severe exacerbations in the withdrawal group. Patients with increased symptom burden at baseline and a history of severe exacerbations may not be optimal candidates for this strategy.

Roflumilast is effective but has side effects

Roflumilast, an oral phosphodiesterase 4 inhibitor, is an anti-inflammatory drug without bronchodilator properties. In randomized controlled trials, the drug was associated with a 17% reduction in acute exacerbations compared with placebo.⁵⁹

Adding roflumilast to either a long-acting beta-2 agonist or a long-acting antimuscarinic agent resulted in a 6% to 8% further reduction in the proportion of patients with exacerbation.^60,61 Martinez et al⁶¹ found that roflumilast added to a regimen of a long-acting beta-2 agonist plus an inhaled corticosteroid reduced moderate to severe exacerbations by 14.2%, even in the presence of tiotropium. Compared with placebo, roflumilast treatment reduced exacerbations necessitating hospitalizations by 23.9%.

The FDA has approved oral roflumilast 500 µg once daily to prevent COPD exacerbations.

Roflumilast is frequently associated with side effects, including gastrointestinal symptoms (chiefly diarrhea), weight loss, and psychiatric effects. A benefit-to-harm study in 2014 concluded that using the drug is only favorable for patients who have a high risk of severe exacerbations, ie, those who have a greater than 22% baseline risk of having at least one exacerbation annually.⁶²

Recommendation. Roflumilast should be reserved for patients who have severe COPD with a chronic bronchitis phenotype (ie, with cough and sputum production) and repeated exacerbations despite an optimal regimen of an inhaled corticosteroid, long-acting beta-2 agonist, and long-acting antimuscarinic agent.

Macrolide antibiotics: Role unclear

Macrolide antibiotics have anti-inflammatory and immunomodulatory activities.

Azithromycin: fewer exacerbations but some side effects. A multicenter trial⁶³ in 1,142 COPD patients randomized to either oral azithromycin 250 mg daily or placebo found a 27% reduction in the risk of COPD exacerbation in the intervention arm. No differences were found between the groups in mortality, hospitalizations, emergency department visits, or respiratory failure. Hearing loss and increased macrolide resistance were noted in the intervention arm. In a secondary subgroup analysis,⁶⁴ no difference in efficacy was found by sex, history of chronic bronchitis, oxygen use, or concomitant COPD treatment.

The COPD: Influence of Macrolides on Exacerbation Frequency in Patients trial⁶⁵ helped refine patient selection for macrolide therapy. In this single-center study, 92 patients with COPD and at least three exacerbations during the year prior to enrollment were randomized to receive either azithromycin 500 mg three times weekly or placebo. Exacerbations in the intervention group were markedly reduced (42%) with no difference in hospitalization rate.

The place of macrolide antibiotics in the treatment strategy of COPD is unclear, and they are not currently part of the GOLD guidelines. Still unknown is the incremental benefit of adding them to existing preventive regimens, cardiovascular safety, side effects, and potential effects on the resident microbial flora. 

Other antibiotics have also been investigated for efficacy in preventing exacerbations.

Moxifloxacin: fewer exacerbations. The Pulsed Moxifloxacin Usage and Its Long-term Impact on the Reduction of Subsequent Exacerbations study⁶⁶ randomized more than 1,000 patients with stable COPD to receive either moxifloxacin 400 mg or placebo daily for 5 days repeated every 8 weeks for six courses. Frequent assessment during the treatment period and for 6 months afterward revealed a reduced exacerbation rate in the intervention group but without benefit in hospitalization rate, mortality, lung function, or health status.

Recommendation. Azithromycin (either 250 mg daily or 500 mg three times weekly) can be considered for patients who have repeated COPD exacerbations despite an optimal regimen of an inhaled corticosteroid, inhaled long-acting beta-2 agonist, and inhaled long-acting antimuscarinic agent. The need to continue azithromycin should be reassessed yearly.

Mucolytics

Greatest benefit to patients not taking inhaled corticosteroids. Mucolytic agents help clear airway secretions by reducing viscosity. N-acetylcysteine and carbocysteine (not available in the United States) also have antioxidant properties that may counteract oxidant stress associated with acute COPD exacerbations.

The Bronchitis Randomized on NAC Cost-Utility Study (BRONCUS)⁶⁷ randomized 523 COPD patients to N-acetylcysteine 600 mg daily or placebo. After 3 years of follow-up, no differences were found in the rate of exacerbations, lung function decline, and quality of life. Subgroup analysis suggested a reduction in exacerbations for patients who were not taking inhaled corticosteroids.

The Effect of Carbocisteine on Acute Exacerbation of Chronic Obstructive Pulmonary Disease (PEACE) study randomized more than 700 patients from multiple centers in China who had COPD and a recent history of exacerbations; they found a 25% lower exacerbation rate over 1 year with carbocysteine vs placebo.⁶⁸ Most of the patients (83%) were not on inhaled corticosteroids, which complemented findings of the BRONCUS trial.

The Effect of High Dose N-acetylcysteine on Air Trapping and Airway Resistance of COPD (HIACE) study randomized 120 patients with stable COPD in a hospital in Hong Kong to either oral N-acetylcysteine (600 mg twice daily) or placebo and found a reduced exacerbation rate of exacerbations. Patients were matched at baseline for inhaled corticosteroid use.⁶⁹

In 2014, the Twice Daily N-acetylcysteine 600 mg for Exacerbations of Chronic Obstructive Pulmonary Disease (PANTHEON) study⁷⁰ randomized 1,006 patients from multiple hospitals in China with a history of moderate to severe COPD and exacerbations to receive either N-acetylcysteine 600 mg twice daily or placebo for 1 year. They found a 22% reduction in exacerbations in the treatment group vs placebo.  

GOLD guidelines² recommend mucolytics for patients with severe COPD and exacerbations when inhaled corticosteroids are not available or affordable.

Recommendation. Mucolytics may be useful for patients with difficulty expectorating and with a history of exacerbations despite appropriate inhaled therapy.

OTHER INTERVENTIONS CAN HELP

Pulmonary rehabilitation provides multiple benefits

Pulmonary rehabilitation increases exercise tolerance and reduces symptoms

Pulmonary rehabilitation increases exercise tolerance and reduces symptom burden in patients with stable COPD. It is also a multidisciplinary effort that may help reinforce adherence to medications, enhance COPD education, and provide closer medical surveillance to patients at high risk for recurrent exacerbations.

A small randomized controlled trial⁷¹ prescribed pulmonary rehabilitation on discharge for a COPD exacerbation and found sustainable improvements in exercise capacity and health status after 3 months.

In a later study,⁷² the same group started pulmonary rehabilitation within a week of hospital discharge and found reduced hospital readmissions over a 3-month period.

Smoking cessation is always worth advocating

A large observational cohort study concluded that current smokers were at a higher risk for COPD exacerbations compared with former smokers.⁷³ Although there are no randomized controlled trials that assess the effects of smoking cessation at the time of COPD exacerbation, we recommend seizing the opportunity to implement this important intervention.

Vaccinations: Influenza and pneumococcal

Influenza vaccination is associated with reduced incidence of hospitalization among patients with cardiopulmonary disease.⁷⁴ A meta-analysis of randomized clinical trials of influenza vaccination for patients with COPD⁷⁵ reported significantly fewer exacerbations from vaccination, mostly owing to fewer episodes occurring after 3 to 4 weeks, coinciding with anticipated vaccine-induced immune protection. Furumoto and colleagues⁷⁶ reported an added benefit of combined vaccination with 23-valent pneumococcal polysaccharide vaccine and influenza vaccine in reducing hospital admissions over influenza vaccination alone. We also recommend providing the 13-valent pneumococcal conjugate vaccine to patients with COPD, particularly for those older than 65, consistent with CDC recommendations.⁷⁷

In contrast to stable chronic obstructive pulmonary disease (COPD),¹ acute exacerbations of COPD pose special management challenges and can significantly increase the risk of morbidity and death and the cost of care.

This review addresses the definition and diagnosis of COPD exacerbations, disease burden and costs, etiology and pathogenesis, and management and prevention strategies.

DEFINITIONS ARE PROBLEMATIC

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) defines a COPD exacer­bation as “an acute event characterized by a worsening of the patient’s respiratory symptoms that is beyond normal day-to-day variations and leads to a change in medication.”² It further categorizes acute exacerbations by severity:

• Mild—treated with increased frequency of doses of existing medications
• Moderate—treated with corticosteroids or antibiotics, or both
• Severe—requires hospital utilization (either emergency room treatment or admission).

Although descriptive and useful for retrospective analyses, this current definition poses ambiguities for clinicians. Day-to-day variation in symptoms is not routinely assessed, so deviations from baseline may be difficult to detect. Although clinical tools are available for assessing symptoms in stable and exacerbated states (eg, the COPD assessment test³ and the Exacerbations of Chronic Pulmonary Disease Tool [EXACT]⁴), they have not been widely adopted in daily practice. Also, according to the current definition, the severity of an exacerbation can be classified only after the course of action is determined, so the severity is not helpful for forming a management strategy at bedside. In addition, physicians may have different thresholds for prescribing antibiotics and corticosteroids.

An earlier definition categorized a COPD exacerbation by the presence of its three cardinal symptoms (ie, increased shortness of breath, sputum volume, and purulence):

• Type I—all three symptoms present
• Type II—two symptoms present
• Type III—one symptom present, accompanied by at least one of the following: upper respiratory tract infection within the past 5 days, unexplained fever, increased wheezing or cough, or 20% increased respiratory rate or heart rate from baseline.

This older definition was successfully used in a prospective clinical trial to identify patients who benefited most from antibiotics for COPD exacerbations.⁵

COPD exacerbation: an acute worsening of respiratory symptoms

Despite these caveats regarding a definition, most clinicians agree on the clinical presentation of a patient with COPD exacerbation: ie, having some combination of shortness of breath, increased sputum volume, and purulence. By the same token, patients with COPD who present with symptoms not typical of an exacerbation should be evaluated for another diagnosis. For instance, Tillie-Leblond et al⁶ reported that 49 (25%) of 197 patients hospitalized with an “unexplained” exacerbation of COPD were eventually diagnosed with pulmonary embolism.

EXACERBATIONS ARE COSTLY

The care of patients with COPD places a great burden on the healthcare system. Using multiple national databases, Ford et al⁷ estimated that medical costs in the United States in 2010 attributable to COPD and its complications were $32.1 billion.

The largest component of direct healthcare costs of COPD is exacerbations and subsequent hospitalizations.⁸ Data from a predominantly Medicare population indicate that the annualized mean COPD-related cost for a patient with no exacerbations was $1,425, compared with $12,765 for a patient with severe exacerbations.⁹ The investigators estimated that reducing exacerbations from two or more to none could save $5,125 per patient per year.

EXACERBATIONS AFFECT HEALTH BEYOND THE EVENT

COPD exacerbations are associated with a faster decline in lung function,¹⁰ reduced quality of life,¹¹ and lost workdays.⁷ A single exacerbation may cause a decline in lung function and health status that may not return to baseline for several months, particularly if another exacerbation occurs within 6 months.^12,13 COPD exacerbations have also been linked to poor clinical outcomes, including death.

In a prospective study in 304 men with COPD followed for 5 years, those who had three or more COPD exacerbations annually were four times as likely to die than patients who did not have an exacerbation.¹⁴ Nevertheless, the relationship with mortality may not be causal: Brusselle pointed out in an editorial¹⁵ that established mortality predictors for COPD do not include exacerbations, and symptomatic patients with COPD without any history of exacerbations are at greater risk of death than those who are asymptomatic but at high risk for exacerbations.

INFECTION + INFLAMMATION = EXACERBATION

An acute COPD exacerbation can be viewed as an acute inflammatory event superimposed on chronic inflammation associated with COPD. Inflammation in the airways increases resistance to air flow with consequent air trapping. Increased resistance and elastic load due to air trapping place respiratory muscles at a mechanical disadvantage and increase the work of breathing.

Infection starts the process

Infections are thought to be the major instigators of COPD exacerbation

Infections, particularly bacterial and viral, are thought to be the major instigators of COPD exacerbation, although environmental factors such as air pollution may also play a role.¹⁶

Airway inflammation is markedly reduced when bacterial infection is eradicated. But if bacterial colonization continues, inflammatory markers remain elevated despite clinical resolution of the exacerbation.¹⁷ Desai et al¹⁸ found that patients with COPD and chronic bronchitis with bacterial colonization had a larger symptom burden than patients without colonization, even without an exacerbation.

Allergic profile increases risk

Although most studies indicate that infection is the main cause of exacerbations, clinicians should consider other mechanisms of inflammation on an individual basis. COPD exacerbations may be phenotyped by measuring inflammatory markers, perhaps as a starting point for tailored therapies.

Bafadhel et al¹⁹ studied 145 patients with COPD over the course of a year and recorded various biomarkers at baseline and during exacerbations. Exacerbations had an inflammatory profile that was predominantly bacterial in 37%, viral in 10%, and eosinophilic in 17%, and had limited changes in the inflammatory profile in 14%. The remaining episodes were combinations of categories. In another study,²⁰ multivariate analysis conducted in two cohorts with COPD found that patients who had an allergic phenotype had more respiratory symptoms and a higher likelihood of COPD exacerbations.

Frequent COPD exacerbations are increasingly recognized as being associated with an asthma-COPD overlap syndrome, consisting of symptoms of increased airflow variability and incompletely reversible airflow obstruction.²¹

Inflammation as a marker of frequent exacerbations

Evidence is accumulating that supports systemic inflammation as a marker of frequent exacerbations. The Copenhagen Heart Study tested for baseline plasma C-reactive protein, fibrinogen, and white blood cell count in 6,574 stable patients with COPD.²² After multivariable adjustment, they found a significantly higher likelihood of having a subsequent exacerbation in patients who had all three biomarkers elevated (odds ratio [OR] 3.7, 95% confidence interval [CI] 1.9–7.4), even in patients with milder COPD and those without previous exacerbations.

Past exacerbations predict risk

A history of exacerbation is the best predictor of future exacerbation

The Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints study²³ found that a history of acute COPD exacerbation was the single best predictor of future exacerbations. This risk factor remained stable over 3 years and was present across the severity of COPD, ie, patients at lower GOLD stages who had a history of frequent exacerbations were likely to have exacerbations during follow-up.

EXACERBATION INCREASES CARDIOVASCULAR RISK

COPD exacerbations increase the risk of cardiovascular events, particularly myocardial infarction.²⁴ During hospitalization for acute exacerbation of COPD, markers of myocardial injury and heart failure may be elevated and are a predictor of death.²⁵

Patel et al²⁶ measured arterial stiffness (aortic pulse wave velocity, a validated measure of cardiovascular risk) and cardiac biomarkers (troponin and N-terminal B-type natriuretic peptide) at baseline in 98 patients and longitudinally during and after a COPD exacerbation. In addition to increased levels of cardiac biomarkers, they found a significant rise in arterial stiffness during the exacerbation event without return to baseline levels over 35 days of follow-up. The arterial stiffness increase was related to airway inflammation as measured by sputum interleukin 6, particularly in patients with documented lower respiratory tract infection.

Retrospective analysis suggests a reduced all-cause mortality rate in COPD patients who are treated with beta-blockers.²⁷

Recommendation. We recommend that patients already taking a selective beta-blocker continue to do so during a COPD exacerbation.

OUTPATIENT MANAGEMENT

Treatment with a combination of a corticosteroid, antibiotic, and bronchodilator addresses the underlying pathophysiologic processes of an acute exacerbation: inflammation, infection, and airway trapping.

Short course of a corticosteroid improves outcomes

A single exacerbation may worsen health status for several months

A 10-day systemic course of a corticosteroid prescribed for COPD exacerbation before discharge from the emergency department was found to offer a small advantage over placebo for reducing treatment failure (unscheduled physician visits, return to emergency room for recurrent symptoms) and improving dyspnea scores and lung function.²⁸ Even just a 3-day course improved measures of respiration (forced expiratory volume in the first second of expiration [FEV₁] and arterial oxygenation) at days 3 and 10, and reduced treatment failures compared with placebo.²⁹

Corticosteroid prescription should not be taken lightly, because adverse effects are common. In a systematic review, one adverse effect (hyperglycemia, weight gain, or insomnia) occurred for every five people treated.³⁰

Identifying subgroups of patients most likely to benefit from corticosteroid treatment may be helpful. Corticosteroids may delay improvement in patients without eosinophilic inflammation and hasten recovery in those with more than 2% peripheral eosinophils.³¹ Siva et al³² found that limiting corticosteroids to patients with sputum eosinophilia reduced corticosteroid use and reduced severe exacerbations compared with standard care.³²

Recommendation. For an acute exacerbation, we prescribe a short course of corticosteroids (eg, prednisone 40 mg daily for 5 to 7 days). Tapering dosing is probably unnecessary because adrenal insufficiency is uncommon before 2 weeks of corticosteroid exposure. Clinicians should weigh the merits of tapering (reduced corticosteroid exposure) against patient inconvenience and difficulty following complicated instructions.

Antibiotics help, but exact strategy uncertain

Although antibiotic therapy is one of the three pillars of COPD exacerbation management, the optimal antimicrobial agent, duration of therapy, and which patients will benefit remain areas of controversy and research. Thus far, large trials have been unable to definitely show the superiority of one antibiotic over another.^33,34

A 1987 randomized controlled trial⁵ of antibiotic therapy in acute exacerbation of COPD found the greatest benefit to patients who had all three cardinal symptoms (ie, increased shortness of breath, sputum volume, and purulence), with less marked but still significant improvement in patients with two symptoms. In a 2012 multicenter trial³⁵ patients with mild to moderate COPD experiencing an exacerbation were treated with either combined amoxicillin and clavulanate or placebo if they had one of the three cardinal symptoms. The antibiotic group had a significantly higher clinical cure rate at days 9 to 11 (74.1% vs 59.9%) as well as a longer time until the next exacerbation (233 vs 160 days).

Recommendation. Optimal antibiotic management of COPD exacerbations may also depend on risk factors. For patients with at least two cardinal symptoms, we favor a scheme akin to one proposed for treating community-acquired pneumonia (Table 1).^16,36

INPATIENT MANAGEMENT

Corticosteroids improve outcomes

A Department of Veterans Affairs cooperative trial³⁷ randomized 271 patients hospitalized with COPD exacerbation to receive either corticosteroids (intravenous followed by oral) or placebo for either 2 weeks or 8 weeks. Corticosteroid recipients had lower rates of treatment failure at 30 and 90 days, defined as death from any cause, need for mechanical ventilation, readmission, or intensification of pharmacologic therapy. Corticosteroid therapy also reduced hospital length of stay and improved the rate of recovery. The longer corticosteroid course was associated with a higher rate of adverse effects.

Oral corticosteroids not inferior to intravenous

Using the same end point of treatment failure as the Veterans Affairs cooperative trial, deJong et al³⁸ demonstrated that prednisone 60 mg by mouth was not inferior to intravenous prednisone. Neither trial demonstrated a difference in mortality between corticosteroid use and placebo.

Short course of a corticosteroid not inferior to a long course

In 2013, the Reduction in the Use of Corticosteroids in Exacerbated COPD (REDUCE) trial³⁹ randomized 314 patients presenting with an acute COPD exacerbation (92% requiring hospital admission) to oral prednisone 40 mg daily for either 5 days or 14 days. They found that the short course was noninferior in preventing exacerbations over the ensuing 6 months in terms of death and the need for mechanical ventilation.

Recommendation. Our threshold for initiating systemic corticosteroid therapy is lower in hospitalized patients than in outpatients. We recommend the regimen of the REDUCE trial: prednisone 40 mg daily for 5 days.

Corticosteroids for patients on ventilatory support

Severe COPD exacerbations requiring admission to intensive care are a significant source of morbidity and mortality, and the strategy of corticosteroid treatment is still under investigation.

Intravenous corticosteroids are effective. A multicenter trial⁴⁰ in 354 patients requiring either invasive or noninvasive mechanical ventilation randomized them to treatment with either intravenous methylprednisolone (tapered) or placebo. Treatment was associated with fewer mechanical ventilation days and a lower rate of noninvasive ventilation failure.

Low-dose oral corticosteroids ineffective. In contrast, an open-label trial⁴¹ of patients requiring ventilatory support and randomized to either oral prednisone (1 mg/kg for up to 10 days) or usual care found no difference in intensive care length of stay or noninvasive ventilation failure. This study used the oral route and smaller doses, and its open-label design might have introduced bias.

Lower-dose steroids better than high-dose. A 2014 cohort study of 17,239 patients admitted to the ICU with acute exacerbations of COPD evaluated outcomes of treatment with high methylprednisolone dosages (> 240 mg per day) vs lower dosages, using propensity score matching.⁴² No mortality difference was found between the groups. The lower dosage group (median methylprednisolone dose 100 mg per day) had shorter hospital and intensive care unit stays, shorter duration of noninvasive positive pressure ventilation, less need for insulin therapy, and fewer fungal infections.

Antibiotics for hospitalized patients

Only scarce data are available on the use of antibiotics for patients hospitalized with COPD exacerbation. In a study of patients hospitalized with COPD exacerbations, adding doxycycline to corticosteroids led to better clinical success and cure rates at 10 days compared with placebo, but the primary end point of clinical success at 30 days was not different between the two groups.⁴³

BRONCHODILATORS: A MAINSTAY OF COPD TREATMENT

Bronchodilators are an important part of treatment of COPD exacerbations in inpatient and outpatient settings.

Nebulized beta-2 agonists are given every 1 to 4 hours. Albuterol at a 2.5-mg dose in each nebulization was found to be as effective as 5 mg for length of hospital stay and recovery of lung function in patients with an acute exacerbation of COPD.⁴⁴

Adding an anticholinergic may help. Nebulized anticholinergics can be given alone or combined with beta-2 agonists. Whether long-acting bronchodilators should be used to manage COPD patients hospitalized with an exacerbation requires further inquiry. In an observational study with historical controls, Drescher and colleagues⁴⁵ found cost savings and shorter hospital stays if tiotropium (a long-acting anticholinergic) was added to the respiratory care protocol, which also included formoterol (a long-acting beta-2 agonist).

OXYGEN: TITRATED APPROACH SAFER

Caution is needed to avoid hyperoxemic hypercapnia in patients on oxygen

Oxygen should be supplied during a COPD exacerbation to ensure adequate oxyhemoglobin saturation. Caution is needed to avoid hyperoxemic hypercapnia, particularly in patients with severe COPD and propensity to ventilatory failure. The routine administration of oxygen at high concentrations during a COPD exacerbation has been associated with a higher mortality rate than with a titrated oxygen approach.⁴⁶ Long-term oxygen treatment started at discharge or as outpatient therapy is associated with reduced hospital admissions and shorter hospital stays for acute exacerbations of COPD.⁴⁷

VENTILATION SUPPORT

Noninvasive positive-pressure ventilation is a useful adjunct to treatment of COPD exacerbations with evidence of ventilatory failure (ie, acute respiratory acidosis), helping to offset the work of breathing until respiratory system mechanics improve. Keenan et al⁴⁸ reviewed 15 randomized controlled trials, involving 636 patients, of noninvasive positive-pressure ventilation in the setting of COPD exacerbation. They concluded that noninvasive positive-pressure ventilation reduced the in-hospital mortality rate and length of stay compared with standard therapy. Noninvasive positive-pressure ventilation is most useful in patients with severe COPD exacerbations and acute respiratory acidosis (pH < 7.35).⁴⁹

Intubation and mechanical ventilation. Although no standards exist for determining which COPD exacerbations may be too severe for noninvasive positive-pressure ventilation, intubation is clearly indicated for impending respiratory failure or hemodynamic instability. Other factors to consider include the greater likelihood of noninvasive positive-pressure ventilation failure in patients with severe respiratory acidosis (pH < 7.25 is associated with a > 50% failure rate) and in those with no improvement in acidosis or respiratory rate during the first hour after initiation of noninvasive positive-pressure ventilation.⁵⁰

PREVENTING EXACERBATIONS

Recent data indicate that COPD exacerbations can often be prevented (Table 2).

Inhaled pharmacotherapy

Inhaled pharmacotherapeutic agents, singly or in combination, reduce the frequency of COPD exacerbations.

Combined long-acting beta-2 agonist and corticosteroid is better than single-agent therapy. In 2007, the Towards a Revolution in COPD Health (TORCH) trial⁵¹ evaluated outpatient therapy in more than 6,000 patients worldwide with either an inhaled long-acting beta-2 agonist (salmeterol), an inhaled corticosteroid (fluticasone), both drugs in combination, or placebo. Patients had baseline prebronchodilator FEV₁ of less than 60% and were followed for 3 years. No difference was found between the groups in the primary end point of deaths, but the annualized rate of moderate to severe exacerbations was reduced by 25% in the group that received combination therapy vs placebo. Combination therapy showed superior efficacy over individual drug therapy in preventing exacerbations. Treatment with the inhaled corticosteroid, whether alone or in combination with salmeterol, increased the risk of pneumonia.

A long-acting antimuscarinic agent is better than placebo. In 2008, the Understanding Potential Long-Term Impacts on Function With Tiotropium (UPLIFT) trial⁵² randomized nearly 6,000 patients with COPD and a postbronchodilator FEV₁ of less than 70% to placebo or tiotropium, a long-acting antimuscarinic agent. Tiotropium reduced the exacerbation rate by 14% compared with placebo and improved quality of life.

Antimuscarinics may be better than beta-2 agonists. Head-to-head comparisons suggest that long-acting antimuscarinic agents are preferable to long-acting beta-2 agonists for preventing COPD exacerbations.^53,54

Triple therapy: evidence is mixed. For patients with severe symptomatic COPD and frequent exacerbations, triple therapy with a combination of an inhaled long-acting antimuscarinic agent, an inhaled long-acting beta-2 agonist, and an inhaled corticosteroid has been suggested.

Data to support this practice are limited. In the Canadian Optimal Trial,⁵⁵ the rate of exacerbations was not different between tiotropium alone, tiotropium plus salmeterol, and triple therapy. However, the rate of hospitalization for severe exacerbation was lower with triple therapy than tiotropium alone. A large, retrospective cohort study also supported triple therapy by finding reduced mortality, hospitalizations, and need for oral corticosteroid bursts compared to combination therapy with an inhaled long-acting beta-2 agonist and an inhaled corticosteroid.⁵⁶

The drawback of triple therapy is an increased incidence of pneumonia associated with combined beta-2 agonist and corticosteroids, most likely due to the corticosteroid component.⁵¹ The risk appears to be higher for higher potency corticosteroids, eg, fluticasone.⁵⁷

In 2014, the Withdrawal of Inhaled Steroids During Optimised Bronchodilator Management (WISDOM) trial⁵⁸ randomized nearly 2,500 patients with a history of COPD exacerbation receiving triple therapy consisting of tiotropium, salmeterol, and inhaled fluticasone to either continue treatment or withdraw the corticosteroid for 3 months. The investigators defined an annualized exacerbation rate of 1.2 (ie, a 20% increase) as the upper limit of the confidence interval for an acceptable therapeutic margin of noninferiority. The study showed that the risk of moderate to severe exacerbations with combined tiotropium and salmeterol was noninferior to triple therapy.

Nevertheless, caution is advised when removing the corticosteroid component from triple therapy. The trial demonstrated a worsening in overall health status, some reduction in lung function, and a transient increase in severe exacerbations in the withdrawal group. Patients with increased symptom burden at baseline and a history of severe exacerbations may not be optimal candidates for this strategy.

Roflumilast is effective but has side effects

Roflumilast, an oral phosphodiesterase 4 inhibitor, is an anti-inflammatory drug without bronchodilator properties. In randomized controlled trials, the drug was associated with a 17% reduction in acute exacerbations compared with placebo.⁵⁹

Adding roflumilast to either a long-acting beta-2 agonist or a long-acting antimuscarinic agent resulted in a 6% to 8% further reduction in the proportion of patients with exacerbation.^60,61 Martinez et al⁶¹ found that roflumilast added to a regimen of a long-acting beta-2 agonist plus an inhaled corticosteroid reduced moderate to severe exacerbations by 14.2%, even in the presence of tiotropium. Compared with placebo, roflumilast treatment reduced exacerbations necessitating hospitalizations by 23.9%.

The FDA has approved oral roflumilast 500 µg once daily to prevent COPD exacerbations.

Roflumilast is frequently associated with side effects, including gastrointestinal symptoms (chiefly diarrhea), weight loss, and psychiatric effects. A benefit-to-harm study in 2014 concluded that using the drug is only favorable for patients who have a high risk of severe exacerbations, ie, those who have a greater than 22% baseline risk of having at least one exacerbation annually.⁶²

Recommendation. Roflumilast should be reserved for patients who have severe COPD with a chronic bronchitis phenotype (ie, with cough and sputum production) and repeated exacerbations despite an optimal regimen of an inhaled corticosteroid, long-acting beta-2 agonist, and long-acting antimuscarinic agent.

Macrolide antibiotics: Role unclear

Macrolide antibiotics have anti-inflammatory and immunomodulatory activities.

Azithromycin: fewer exacerbations but some side effects. A multicenter trial⁶³ in 1,142 COPD patients randomized to either oral azithromycin 250 mg daily or placebo found a 27% reduction in the risk of COPD exacerbation in the intervention arm. No differences were found between the groups in mortality, hospitalizations, emergency department visits, or respiratory failure. Hearing loss and increased macrolide resistance were noted in the intervention arm. In a secondary subgroup analysis,⁶⁴ no difference in efficacy was found by sex, history of chronic bronchitis, oxygen use, or concomitant COPD treatment.

The COPD: Influence of Macrolides on Exacerbation Frequency in Patients trial⁶⁵ helped refine patient selection for macrolide therapy. In this single-center study, 92 patients with COPD and at least three exacerbations during the year prior to enrollment were randomized to receive either azithromycin 500 mg three times weekly or placebo. Exacerbations in the intervention group were markedly reduced (42%) with no difference in hospitalization rate.

The place of macrolide antibiotics in the treatment strategy of COPD is unclear, and they are not currently part of the GOLD guidelines. Still unknown is the incremental benefit of adding them to existing preventive regimens, cardiovascular safety, side effects, and potential effects on the resident microbial flora. 

Other antibiotics have also been investigated for efficacy in preventing exacerbations.

Moxifloxacin: fewer exacerbations. The Pulsed Moxifloxacin Usage and Its Long-term Impact on the Reduction of Subsequent Exacerbations study⁶⁶ randomized more than 1,000 patients with stable COPD to receive either moxifloxacin 400 mg or placebo daily for 5 days repeated every 8 weeks for six courses. Frequent assessment during the treatment period and for 6 months afterward revealed a reduced exacerbation rate in the intervention group but without benefit in hospitalization rate, mortality, lung function, or health status.

Recommendation. Azithromycin (either 250 mg daily or 500 mg three times weekly) can be considered for patients who have repeated COPD exacerbations despite an optimal regimen of an inhaled corticosteroid, inhaled long-acting beta-2 agonist, and inhaled long-acting antimuscarinic agent. The need to continue azithromycin should be reassessed yearly.

Mucolytics

Greatest benefit to patients not taking inhaled corticosteroids. Mucolytic agents help clear airway secretions by reducing viscosity. N-acetylcysteine and carbocysteine (not available in the United States) also have antioxidant properties that may counteract oxidant stress associated with acute COPD exacerbations.

The Bronchitis Randomized on NAC Cost-Utility Study (BRONCUS)⁶⁷ randomized 523 COPD patients to N-acetylcysteine 600 mg daily or placebo. After 3 years of follow-up, no differences were found in the rate of exacerbations, lung function decline, and quality of life. Subgroup analysis suggested a reduction in exacerbations for patients who were not taking inhaled corticosteroids.

The Effect of Carbocisteine on Acute Exacerbation of Chronic Obstructive Pulmonary Disease (PEACE) study randomized more than 700 patients from multiple centers in China who had COPD and a recent history of exacerbations; they found a 25% lower exacerbation rate over 1 year with carbocysteine vs placebo.⁶⁸ Most of the patients (83%) were not on inhaled corticosteroids, which complemented findings of the BRONCUS trial.

The Effect of High Dose N-acetylcysteine on Air Trapping and Airway Resistance of COPD (HIACE) study randomized 120 patients with stable COPD in a hospital in Hong Kong to either oral N-acetylcysteine (600 mg twice daily) or placebo and found a reduced exacerbation rate of exacerbations. Patients were matched at baseline for inhaled corticosteroid use.⁶⁹

In 2014, the Twice Daily N-acetylcysteine 600 mg for Exacerbations of Chronic Obstructive Pulmonary Disease (PANTHEON) study⁷⁰ randomized 1,006 patients from multiple hospitals in China with a history of moderate to severe COPD and exacerbations to receive either N-acetylcysteine 600 mg twice daily or placebo for 1 year. They found a 22% reduction in exacerbations in the treatment group vs placebo.  

GOLD guidelines² recommend mucolytics for patients with severe COPD and exacerbations when inhaled corticosteroids are not available or affordable.

Recommendation. Mucolytics may be useful for patients with difficulty expectorating and with a history of exacerbations despite appropriate inhaled therapy.

OTHER INTERVENTIONS CAN HELP

Pulmonary rehabilitation provides multiple benefits

Pulmonary rehabilitation increases exercise tolerance and reduces symptoms

Pulmonary rehabilitation increases exercise tolerance and reduces symptom burden in patients with stable COPD. It is also a multidisciplinary effort that may help reinforce adherence to medications, enhance COPD education, and provide closer medical surveillance to patients at high risk for recurrent exacerbations.

A small randomized controlled trial⁷¹ prescribed pulmonary rehabilitation on discharge for a COPD exacerbation and found sustainable improvements in exercise capacity and health status after 3 months.

In a later study,⁷² the same group started pulmonary rehabilitation within a week of hospital discharge and found reduced hospital readmissions over a 3-month period.

Smoking cessation is always worth advocating

A large observational cohort study concluded that current smokers were at a higher risk for COPD exacerbations compared with former smokers.⁷³ Although there are no randomized controlled trials that assess the effects of smoking cessation at the time of COPD exacerbation, we recommend seizing the opportunity to implement this important intervention.

Vaccinations: Influenza and pneumococcal

Influenza vaccination is associated with reduced incidence of hospitalization among patients with cardiopulmonary disease.⁷⁴ A meta-analysis of randomized clinical trials of influenza vaccination for patients with COPD⁷⁵ reported significantly fewer exacerbations from vaccination, mostly owing to fewer episodes occurring after 3 to 4 weeks, coinciding with anticipated vaccine-induced immune protection. Furumoto and colleagues⁷⁶ reported an added benefit of combined vaccination with 23-valent pneumococcal polysaccharide vaccine and influenza vaccine in reducing hospital admissions over influenza vaccination alone. We also recommend providing the 13-valent pneumococcal conjugate vaccine to patients with COPD, particularly for those older than 65, consistent with CDC recommendations.⁷⁷

In contrast to stable chronic obstructive pulmonary disease (COPD),¹ acute exacerbations of COPD pose special management challenges and can significantly increase the risk of morbidity and death and the cost of care.

This review addresses the definition and diagnosis of COPD exacerbations, disease burden and costs, etiology and pathogenesis, and management and prevention strategies.

DEFINITIONS ARE PROBLEMATIC

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) defines a COPD exacer­bation as “an acute event characterized by a worsening of the patient’s respiratory symptoms that is beyond normal day-to-day variations and leads to a change in medication.”² It further categorizes acute exacerbations by severity:

• Mild—treated with increased frequency of doses of existing medications
• Moderate—treated with corticosteroids or antibiotics, or both
• Severe—requires hospital utilization (either emergency room treatment or admission).

Although descriptive and useful for retrospective analyses, this current definition poses ambiguities for clinicians. Day-to-day variation in symptoms is not routinely assessed, so deviations from baseline may be difficult to detect. Although clinical tools are available for assessing symptoms in stable and exacerbated states (eg, the COPD assessment test³ and the Exacerbations of Chronic Pulmonary Disease Tool [EXACT]⁴), they have not been widely adopted in daily practice. Also, according to the current definition, the severity of an exacerbation can be classified only after the course of action is determined, so the severity is not helpful for forming a management strategy at bedside. In addition, physicians may have different thresholds for prescribing antibiotics and corticosteroids.

An earlier definition categorized a COPD exacerbation by the presence of its three cardinal symptoms (ie, increased shortness of breath, sputum volume, and purulence):

• Type I—all three symptoms present
• Type II—two symptoms present
• Type III—one symptom present, accompanied by at least one of the following: upper respiratory tract infection within the past 5 days, unexplained fever, increased wheezing or cough, or 20% increased respiratory rate or heart rate from baseline.

This older definition was successfully used in a prospective clinical trial to identify patients who benefited most from antibiotics for COPD exacerbations.⁵

COPD exacerbation: an acute worsening of respiratory symptoms

Despite these caveats regarding a definition, most clinicians agree on the clinical presentation of a patient with COPD exacerbation: ie, having some combination of shortness of breath, increased sputum volume, and purulence. By the same token, patients with COPD who present with symptoms not typical of an exacerbation should be evaluated for another diagnosis. For instance, Tillie-Leblond et al⁶ reported that 49 (25%) of 197 patients hospitalized with an “unexplained” exacerbation of COPD were eventually diagnosed with pulmonary embolism.

EXACERBATIONS ARE COSTLY

The care of patients with COPD places a great burden on the healthcare system. Using multiple national databases, Ford et al⁷ estimated that medical costs in the United States in 2010 attributable to COPD and its complications were $32.1 billion.

The largest component of direct healthcare costs of COPD is exacerbations and subsequent hospitalizations.⁸ Data from a predominantly Medicare population indicate that the annualized mean COPD-related cost for a patient with no exacerbations was $1,425, compared with $12,765 for a patient with severe exacerbations.⁹ The investigators estimated that reducing exacerbations from two or more to none could save $5,125 per patient per year.

EXACERBATIONS AFFECT HEALTH BEYOND THE EVENT

COPD exacerbations are associated with a faster decline in lung function,¹⁰ reduced quality of life,¹¹ and lost workdays.⁷ A single exacerbation may cause a decline in lung function and health status that may not return to baseline for several months, particularly if another exacerbation occurs within 6 months.^12,13 COPD exacerbations have also been linked to poor clinical outcomes, including death.

In a prospective study in 304 men with COPD followed for 5 years, those who had three or more COPD exacerbations annually were four times as likely to die than patients who did not have an exacerbation.¹⁴ Nevertheless, the relationship with mortality may not be causal: Brusselle pointed out in an editorial¹⁵ that established mortality predictors for COPD do not include exacerbations, and symptomatic patients with COPD without any history of exacerbations are at greater risk of death than those who are asymptomatic but at high risk for exacerbations.

INFECTION + INFLAMMATION = EXACERBATION

An acute COPD exacerbation can be viewed as an acute inflammatory event superimposed on chronic inflammation associated with COPD. Inflammation in the airways increases resistance to air flow with consequent air trapping. Increased resistance and elastic load due to air trapping place respiratory muscles at a mechanical disadvantage and increase the work of breathing.

Infection starts the process

Infections are thought to be the major instigators of COPD exacerbation

Infections, particularly bacterial and viral, are thought to be the major instigators of COPD exacerbation, although environmental factors such as air pollution may also play a role.¹⁶

Airway inflammation is markedly reduced when bacterial infection is eradicated. But if bacterial colonization continues, inflammatory markers remain elevated despite clinical resolution of the exacerbation.¹⁷ Desai et al¹⁸ found that patients with COPD and chronic bronchitis with bacterial colonization had a larger symptom burden than patients without colonization, even without an exacerbation.

Allergic profile increases risk

Although most studies indicate that infection is the main cause of exacerbations, clinicians should consider other mechanisms of inflammation on an individual basis. COPD exacerbations may be phenotyped by measuring inflammatory markers, perhaps as a starting point for tailored therapies.

Bafadhel et al¹⁹ studied 145 patients with COPD over the course of a year and recorded various biomarkers at baseline and during exacerbations. Exacerbations had an inflammatory profile that was predominantly bacterial in 37%, viral in 10%, and eosinophilic in 17%, and had limited changes in the inflammatory profile in 14%. The remaining episodes were combinations of categories. In another study,²⁰ multivariate analysis conducted in two cohorts with COPD found that patients who had an allergic phenotype had more respiratory symptoms and a higher likelihood of COPD exacerbations.

Frequent COPD exacerbations are increasingly recognized as being associated with an asthma-COPD overlap syndrome, consisting of symptoms of increased airflow variability and incompletely reversible airflow obstruction.²¹

Inflammation as a marker of frequent exacerbations

Evidence is accumulating that supports systemic inflammation as a marker of frequent exacerbations. The Copenhagen Heart Study tested for baseline plasma C-reactive protein, fibrinogen, and white blood cell count in 6,574 stable patients with COPD.²² After multivariable adjustment, they found a significantly higher likelihood of having a subsequent exacerbation in patients who had all three biomarkers elevated (odds ratio [OR] 3.7, 95% confidence interval [CI] 1.9–7.4), even in patients with milder COPD and those without previous exacerbations.

Past exacerbations predict risk

A history of exacerbation is the best predictor of future exacerbation

The Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints study²³ found that a history of acute COPD exacerbation was the single best predictor of future exacerbations. This risk factor remained stable over 3 years and was present across the severity of COPD, ie, patients at lower GOLD stages who had a history of frequent exacerbations were likely to have exacerbations during follow-up.

EXACERBATION INCREASES CARDIOVASCULAR RISK

COPD exacerbations increase the risk of cardiovascular events, particularly myocardial infarction.²⁴ During hospitalization for acute exacerbation of COPD, markers of myocardial injury and heart failure may be elevated and are a predictor of death.²⁵

Patel et al²⁶ measured arterial stiffness (aortic pulse wave velocity, a validated measure of cardiovascular risk) and cardiac biomarkers (troponin and N-terminal B-type natriuretic peptide) at baseline in 98 patients and longitudinally during and after a COPD exacerbation. In addition to increased levels of cardiac biomarkers, they found a significant rise in arterial stiffness during the exacerbation event without return to baseline levels over 35 days of follow-up. The arterial stiffness increase was related to airway inflammation as measured by sputum interleukin 6, particularly in patients with documented lower respiratory tract infection.

Retrospective analysis suggests a reduced all-cause mortality rate in COPD patients who are treated with beta-blockers.²⁷

Recommendation. We recommend that patients already taking a selective beta-blocker continue to do so during a COPD exacerbation.

OUTPATIENT MANAGEMENT

Treatment with a combination of a corticosteroid, antibiotic, and bronchodilator addresses the underlying pathophysiologic processes of an acute exacerbation: inflammation, infection, and airway trapping.

Short course of a corticosteroid improves outcomes

A single exacerbation may worsen health status for several months

A 10-day systemic course of a corticosteroid prescribed for COPD exacerbation before discharge from the emergency department was found to offer a small advantage over placebo for reducing treatment failure (unscheduled physician visits, return to emergency room for recurrent symptoms) and improving dyspnea scores and lung function.²⁸ Even just a 3-day course improved measures of respiration (forced expiratory volume in the first second of expiration [FEV₁] and arterial oxygenation) at days 3 and 10, and reduced treatment failures compared with placebo.²⁹

Corticosteroid prescription should not be taken lightly, because adverse effects are common. In a systematic review, one adverse effect (hyperglycemia, weight gain, or insomnia) occurred for every five people treated.³⁰

Identifying subgroups of patients most likely to benefit from corticosteroid treatment may be helpful. Corticosteroids may delay improvement in patients without eosinophilic inflammation and hasten recovery in those with more than 2% peripheral eosinophils.³¹ Siva et al³² found that limiting corticosteroids to patients with sputum eosinophilia reduced corticosteroid use and reduced severe exacerbations compared with standard care.³²

Recommendation. For an acute exacerbation, we prescribe a short course of corticosteroids (eg, prednisone 40 mg daily for 5 to 7 days). Tapering dosing is probably unnecessary because adrenal insufficiency is uncommon before 2 weeks of corticosteroid exposure. Clinicians should weigh the merits of tapering (reduced corticosteroid exposure) against patient inconvenience and difficulty following complicated instructions.

Antibiotics help, but exact strategy uncertain

Although antibiotic therapy is one of the three pillars of COPD exacerbation management, the optimal antimicrobial agent, duration of therapy, and which patients will benefit remain areas of controversy and research. Thus far, large trials have been unable to definitely show the superiority of one antibiotic over another.^33,34

A 1987 randomized controlled trial⁵ of antibiotic therapy in acute exacerbation of COPD found the greatest benefit to patients who had all three cardinal symptoms (ie, increased shortness of breath, sputum volume, and purulence), with less marked but still significant improvement in patients with two symptoms. In a 2012 multicenter trial³⁵ patients with mild to moderate COPD experiencing an exacerbation were treated with either combined amoxicillin and clavulanate or placebo if they had one of the three cardinal symptoms. The antibiotic group had a significantly higher clinical cure rate at days 9 to 11 (74.1% vs 59.9%) as well as a longer time until the next exacerbation (233 vs 160 days).

Recommendation. Optimal antibiotic management of COPD exacerbations may also depend on risk factors. For patients with at least two cardinal symptoms, we favor a scheme akin to one proposed for treating community-acquired pneumonia (Table 1).^16,36

INPATIENT MANAGEMENT

Corticosteroids improve outcomes

A Department of Veterans Affairs cooperative trial³⁷ randomized 271 patients hospitalized with COPD exacerbation to receive either corticosteroids (intravenous followed by oral) or placebo for either 2 weeks or 8 weeks. Corticosteroid recipients had lower rates of treatment failure at 30 and 90 days, defined as death from any cause, need for mechanical ventilation, readmission, or intensification of pharmacologic therapy. Corticosteroid therapy also reduced hospital length of stay and improved the rate of recovery. The longer corticosteroid course was associated with a higher rate of adverse effects.

Oral corticosteroids not inferior to intravenous

Using the same end point of treatment failure as the Veterans Affairs cooperative trial, deJong et al³⁸ demonstrated that prednisone 60 mg by mouth was not inferior to intravenous prednisone. Neither trial demonstrated a difference in mortality between corticosteroid use and placebo.

Short course of a corticosteroid not inferior to a long course

In 2013, the Reduction in the Use of Corticosteroids in Exacerbated COPD (REDUCE) trial³⁹ randomized 314 patients presenting with an acute COPD exacerbation (92% requiring hospital admission) to oral prednisone 40 mg daily for either 5 days or 14 days. They found that the short course was noninferior in preventing exacerbations over the ensuing 6 months in terms of death and the need for mechanical ventilation.

Recommendation. Our threshold for initiating systemic corticosteroid therapy is lower in hospitalized patients than in outpatients. We recommend the regimen of the REDUCE trial: prednisone 40 mg daily for 5 days.

Corticosteroids for patients on ventilatory support

Severe COPD exacerbations requiring admission to intensive care are a significant source of morbidity and mortality, and the strategy of corticosteroid treatment is still under investigation.

Intravenous corticosteroids are effective. A multicenter trial⁴⁰ in 354 patients requiring either invasive or noninvasive mechanical ventilation randomized them to treatment with either intravenous methylprednisolone (tapered) or placebo. Treatment was associated with fewer mechanical ventilation days and a lower rate of noninvasive ventilation failure.

Low-dose oral corticosteroids ineffective. In contrast, an open-label trial⁴¹ of patients requiring ventilatory support and randomized to either oral prednisone (1 mg/kg for up to 10 days) or usual care found no difference in intensive care length of stay or noninvasive ventilation failure. This study used the oral route and smaller doses, and its open-label design might have introduced bias.

Lower-dose steroids better than high-dose. A 2014 cohort study of 17,239 patients admitted to the ICU with acute exacerbations of COPD evaluated outcomes of treatment with high methylprednisolone dosages (> 240 mg per day) vs lower dosages, using propensity score matching.⁴² No mortality difference was found between the groups. The lower dosage group (median methylprednisolone dose 100 mg per day) had shorter hospital and intensive care unit stays, shorter duration of noninvasive positive pressure ventilation, less need for insulin therapy, and fewer fungal infections.

Antibiotics for hospitalized patients

Only scarce data are available on the use of antibiotics for patients hospitalized with COPD exacerbation. In a study of patients hospitalized with COPD exacerbations, adding doxycycline to corticosteroids led to better clinical success and cure rates at 10 days compared with placebo, but the primary end point of clinical success at 30 days was not different between the two groups.⁴³

BRONCHODILATORS: A MAINSTAY OF COPD TREATMENT

Bronchodilators are an important part of treatment of COPD exacerbations in inpatient and outpatient settings.

Nebulized beta-2 agonists are given every 1 to 4 hours. Albuterol at a 2.5-mg dose in each nebulization was found to be as effective as 5 mg for length of hospital stay and recovery of lung function in patients with an acute exacerbation of COPD.⁴⁴

Adding an anticholinergic may help. Nebulized anticholinergics can be given alone or combined with beta-2 agonists. Whether long-acting bronchodilators should be used to manage COPD patients hospitalized with an exacerbation requires further inquiry. In an observational study with historical controls, Drescher and colleagues⁴⁵ found cost savings and shorter hospital stays if tiotropium (a long-acting anticholinergic) was added to the respiratory care protocol, which also included formoterol (a long-acting beta-2 agonist).

OXYGEN: TITRATED APPROACH SAFER

Caution is needed to avoid hyperoxemic hypercapnia in patients on oxygen

Oxygen should be supplied during a COPD exacerbation to ensure adequate oxyhemoglobin saturation. Caution is needed to avoid hyperoxemic hypercapnia, particularly in patients with severe COPD and propensity to ventilatory failure. The routine administration of oxygen at high concentrations during a COPD exacerbation has been associated with a higher mortality rate than with a titrated oxygen approach.⁴⁶ Long-term oxygen treatment started at discharge or as outpatient therapy is associated with reduced hospital admissions and shorter hospital stays for acute exacerbations of COPD.⁴⁷

VENTILATION SUPPORT

Noninvasive positive-pressure ventilation is a useful adjunct to treatment of COPD exacerbations with evidence of ventilatory failure (ie, acute respiratory acidosis), helping to offset the work of breathing until respiratory system mechanics improve. Keenan et al⁴⁸ reviewed 15 randomized controlled trials, involving 636 patients, of noninvasive positive-pressure ventilation in the setting of COPD exacerbation. They concluded that noninvasive positive-pressure ventilation reduced the in-hospital mortality rate and length of stay compared with standard therapy. Noninvasive positive-pressure ventilation is most useful in patients with severe COPD exacerbations and acute respiratory acidosis (pH < 7.35).⁴⁹

Intubation and mechanical ventilation. Although no standards exist for determining which COPD exacerbations may be too severe for noninvasive positive-pressure ventilation, intubation is clearly indicated for impending respiratory failure or hemodynamic instability. Other factors to consider include the greater likelihood of noninvasive positive-pressure ventilation failure in patients with severe respiratory acidosis (pH < 7.25 is associated with a > 50% failure rate) and in those with no improvement in acidosis or respiratory rate during the first hour after initiation of noninvasive positive-pressure ventilation.⁵⁰

PREVENTING EXACERBATIONS

Recent data indicate that COPD exacerbations can often be prevented (Table 2).

Inhaled pharmacotherapy

Inhaled pharmacotherapeutic agents, singly or in combination, reduce the frequency of COPD exacerbations.

Combined long-acting beta-2 agonist and corticosteroid is better than single-agent therapy. In 2007, the Towards a Revolution in COPD Health (TORCH) trial⁵¹ evaluated outpatient therapy in more than 6,000 patients worldwide with either an inhaled long-acting beta-2 agonist (salmeterol), an inhaled corticosteroid (fluticasone), both drugs in combination, or placebo. Patients had baseline prebronchodilator FEV₁ of less than 60% and were followed for 3 years. No difference was found between the groups in the primary end point of deaths, but the annualized rate of moderate to severe exacerbations was reduced by 25% in the group that received combination therapy vs placebo. Combination therapy showed superior efficacy over individual drug therapy in preventing exacerbations. Treatment with the inhaled corticosteroid, whether alone or in combination with salmeterol, increased the risk of pneumonia.

A long-acting antimuscarinic agent is better than placebo. In 2008, the Understanding Potential Long-Term Impacts on Function With Tiotropium (UPLIFT) trial⁵² randomized nearly 6,000 patients with COPD and a postbronchodilator FEV₁ of less than 70% to placebo or tiotropium, a long-acting antimuscarinic agent. Tiotropium reduced the exacerbation rate by 14% compared with placebo and improved quality of life.

Antimuscarinics may be better than beta-2 agonists. Head-to-head comparisons suggest that long-acting antimuscarinic agents are preferable to long-acting beta-2 agonists for preventing COPD exacerbations.^53,54

Triple therapy: evidence is mixed. For patients with severe symptomatic COPD and frequent exacerbations, triple therapy with a combination of an inhaled long-acting antimuscarinic agent, an inhaled long-acting beta-2 agonist, and an inhaled corticosteroid has been suggested.

Data to support this practice are limited. In the Canadian Optimal Trial,⁵⁵ the rate of exacerbations was not different between tiotropium alone, tiotropium plus salmeterol, and triple therapy. However, the rate of hospitalization for severe exacerbation was lower with triple therapy than tiotropium alone. A large, retrospective cohort study also supported triple therapy by finding reduced mortality, hospitalizations, and need for oral corticosteroid bursts compared to combination therapy with an inhaled long-acting beta-2 agonist and an inhaled corticosteroid.⁵⁶

The drawback of triple therapy is an increased incidence of pneumonia associated with combined beta-2 agonist and corticosteroids, most likely due to the corticosteroid component.⁵¹ The risk appears to be higher for higher potency corticosteroids, eg, fluticasone.⁵⁷

In 2014, the Withdrawal of Inhaled Steroids During Optimised Bronchodilator Management (WISDOM) trial⁵⁸ randomized nearly 2,500 patients with a history of COPD exacerbation receiving triple therapy consisting of tiotropium, salmeterol, and inhaled fluticasone to either continue treatment or withdraw the corticosteroid for 3 months. The investigators defined an annualized exacerbation rate of 1.2 (ie, a 20% increase) as the upper limit of the confidence interval for an acceptable therapeutic margin of noninferiority. The study showed that the risk of moderate to severe exacerbations with combined tiotropium and salmeterol was noninferior to triple therapy.

Nevertheless, caution is advised when removing the corticosteroid component from triple therapy. The trial demonstrated a worsening in overall health status, some reduction in lung function, and a transient increase in severe exacerbations in the withdrawal group. Patients with increased symptom burden at baseline and a history of severe exacerbations may not be optimal candidates for this strategy.

Roflumilast is effective but has side effects

Roflumilast, an oral phosphodiesterase 4 inhibitor, is an anti-inflammatory drug without bronchodilator properties. In randomized controlled trials, the drug was associated with a 17% reduction in acute exacerbations compared with placebo.⁵⁹

Adding roflumilast to either a long-acting beta-2 agonist or a long-acting antimuscarinic agent resulted in a 6% to 8% further reduction in the proportion of patients with exacerbation.^60,61 Martinez et al⁶¹ found that roflumilast added to a regimen of a long-acting beta-2 agonist plus an inhaled corticosteroid reduced moderate to severe exacerbations by 14.2%, even in the presence of tiotropium. Compared with placebo, roflumilast treatment reduced exacerbations necessitating hospitalizations by 23.9%.

The FDA has approved oral roflumilast 500 µg once daily to prevent COPD exacerbations.

Roflumilast is frequently associated with side effects, including gastrointestinal symptoms (chiefly diarrhea), weight loss, and psychiatric effects. A benefit-to-harm study in 2014 concluded that using the drug is only favorable for patients who have a high risk of severe exacerbations, ie, those who have a greater than 22% baseline risk of having at least one exacerbation annually.⁶²

Recommendation. Roflumilast should be reserved for patients who have severe COPD with a chronic bronchitis phenotype (ie, with cough and sputum production) and repeated exacerbations despite an optimal regimen of an inhaled corticosteroid, long-acting beta-2 agonist, and long-acting antimuscarinic agent.

Macrolide antibiotics: Role unclear

Macrolide antibiotics have anti-inflammatory and immunomodulatory activities.

Azithromycin: fewer exacerbations but some side effects. A multicenter trial⁶³ in 1,142 COPD patients randomized to either oral azithromycin 250 mg daily or placebo found a 27% reduction in the risk of COPD exacerbation in the intervention arm. No differences were found between the groups in mortality, hospitalizations, emergency department visits, or respiratory failure. Hearing loss and increased macrolide resistance were noted in the intervention arm. In a secondary subgroup analysis,⁶⁴ no difference in efficacy was found by sex, history of chronic bronchitis, oxygen use, or concomitant COPD treatment.

The COPD: Influence of Macrolides on Exacerbation Frequency in Patients trial⁶⁵ helped refine patient selection for macrolide therapy. In this single-center study, 92 patients with COPD and at least three exacerbations during the year prior to enrollment were randomized to receive either azithromycin 500 mg three times weekly or placebo. Exacerbations in the intervention group were markedly reduced (42%) with no difference in hospitalization rate.

The place of macrolide antibiotics in the treatment strategy of COPD is unclear, and they are not currently part of the GOLD guidelines. Still unknown is the incremental benefit of adding them to existing preventive regimens, cardiovascular safety, side effects, and potential effects on the resident microbial flora. 

Other antibiotics have also been investigated for efficacy in preventing exacerbations.

Moxifloxacin: fewer exacerbations. The Pulsed Moxifloxacin Usage and Its Long-term Impact on the Reduction of Subsequent Exacerbations study⁶⁶ randomized more than 1,000 patients with stable COPD to receive either moxifloxacin 400 mg or placebo daily for 5 days repeated every 8 weeks for six courses. Frequent assessment during the treatment period and for 6 months afterward revealed a reduced exacerbation rate in the intervention group but without benefit in hospitalization rate, mortality, lung function, or health status.

Recommendation. Azithromycin (either 250 mg daily or 500 mg three times weekly) can be considered for patients who have repeated COPD exacerbations despite an optimal regimen of an inhaled corticosteroid, inhaled long-acting beta-2 agonist, and inhaled long-acting antimuscarinic agent. The need to continue azithromycin should be reassessed yearly.

Mucolytics

Greatest benefit to patients not taking inhaled corticosteroids. Mucolytic agents help clear airway secretions by reducing viscosity. N-acetylcysteine and carbocysteine (not available in the United States) also have antioxidant properties that may counteract oxidant stress associated with acute COPD exacerbations.

The Bronchitis Randomized on NAC Cost-Utility Study (BRONCUS)⁶⁷ randomized 523 COPD patients to N-acetylcysteine 600 mg daily or placebo. After 3 years of follow-up, no differences were found in the rate of exacerbations, lung function decline, and quality of life. Subgroup analysis suggested a reduction in exacerbations for patients who were not taking inhaled corticosteroids.

The Effect of Carbocisteine on Acute Exacerbation of Chronic Obstructive Pulmonary Disease (PEACE) study randomized more than 700 patients from multiple centers in China who had COPD and a recent history of exacerbations; they found a 25% lower exacerbation rate over 1 year with carbocysteine vs placebo.⁶⁸ Most of the patients (83%) were not on inhaled corticosteroids, which complemented findings of the BRONCUS trial.

The Effect of High Dose N-acetylcysteine on Air Trapping and Airway Resistance of COPD (HIACE) study randomized 120 patients with stable COPD in a hospital in Hong Kong to either oral N-acetylcysteine (600 mg twice daily) or placebo and found a reduced exacerbation rate of exacerbations. Patients were matched at baseline for inhaled corticosteroid use.⁶⁹

In 2014, the Twice Daily N-acetylcysteine 600 mg for Exacerbations of Chronic Obstructive Pulmonary Disease (PANTHEON) study⁷⁰ randomized 1,006 patients from multiple hospitals in China with a history of moderate to severe COPD and exacerbations to receive either N-acetylcysteine 600 mg twice daily or placebo for 1 year. They found a 22% reduction in exacerbations in the treatment group vs placebo.  

GOLD guidelines² recommend mucolytics for patients with severe COPD and exacerbations when inhaled corticosteroids are not available or affordable.

Recommendation. Mucolytics may be useful for patients with difficulty expectorating and with a history of exacerbations despite appropriate inhaled therapy.

OTHER INTERVENTIONS CAN HELP

Pulmonary rehabilitation provides multiple benefits

Pulmonary rehabilitation increases exercise tolerance and reduces symptoms

Pulmonary rehabilitation increases exercise tolerance and reduces symptom burden in patients with stable COPD. It is also a multidisciplinary effort that may help reinforce adherence to medications, enhance COPD education, and provide closer medical surveillance to patients at high risk for recurrent exacerbations.

A small randomized controlled trial⁷¹ prescribed pulmonary rehabilitation on discharge for a COPD exacerbation and found sustainable improvements in exercise capacity and health status after 3 months.

In a later study,⁷² the same group started pulmonary rehabilitation within a week of hospital discharge and found reduced hospital readmissions over a 3-month period.

Smoking cessation is always worth advocating

A large observational cohort study concluded that current smokers were at a higher risk for COPD exacerbations compared with former smokers.⁷³ Although there are no randomized controlled trials that assess the effects of smoking cessation at the time of COPD exacerbation, we recommend seizing the opportunity to implement this important intervention.

Vaccinations: Influenza and pneumococcal

Influenza vaccination is associated with reduced incidence of hospitalization among patients with cardiopulmonary disease.⁷⁴ A meta-analysis of randomized clinical trials of influenza vaccination for patients with COPD⁷⁵ reported significantly fewer exacerbations from vaccination, mostly owing to fewer episodes occurring after 3 to 4 weeks, coinciding with anticipated vaccine-induced immune protection. Furumoto and colleagues⁷⁶ reported an added benefit of combined vaccination with 23-valent pneumococcal polysaccharide vaccine and influenza vaccine in reducing hospital admissions over influenza vaccination alone. We also recommend providing the 13-valent pneumococcal conjugate vaccine to patients with COPD, particularly for those older than 65, consistent with CDC recommendations.⁷⁷

Chronic obstructive pulmonary disease (COPD) has seen several changes in its assessment and treatment in recent years, reflecting advances in our understanding of this common and serious disease.

This review updates busy practitioners on the major advances, including new assessment tools and new therapies.

COMMON AND INCREASING

COPD is the third leading cause of death in the United States, behind heart disease and cancer,¹ and of the top five (the others being stroke and accidents), it is the only one that increased in incidence between 2007 and 2010.² The 11th leading cause of disability-adjusted life years worldwide in 2002, COPD is projected to become the seventh by the year 2030.³

CHARACTERIZED BY OBSTRUCTION

COPD is characterized by persistent and progressive airflow obstruction associated with chronic airway inflammation in response to noxious particles and gases. Disease of the small airways (inflammation, mucus plugging, and fibrosis) and parenchymal destruction (emphysema) limit the flow of air.

COPD is diagnosed by spirometry—specifically, a ratio of forced expiratory volume in 1 second to forced vital capacity (FEV₁/FVC) of less than 0.7 after a bronchodilator is given. The severity of airflow limitation is revealed by the FEV₁ as a percent of the predicted value.

Cigarette smoking is the major cause of COPD, but the prevalence of COPD is 6.6% in people who have never smoked, and one-fourth of COPD patients in the United States have never smoked.⁴

GOLDEN GOALS: FEWER SYMPTOMS, LOWER RISK

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) periodically issues evidence-based statements on how to prevent and treat COPD.

In its 2013 update,⁵ GOLD suggested two goals: improving symptoms and reducing the risk of death, exacerbations, progression of disease, and treatment-related adverse effects. The latter goal—reducing risk—is relatively new.

Exacerbations are acute inflammatory events superimposed on chronic inflammation. The inflammation is often brought on by infection⁶ and increases the risk of death⁷ and the risk of a faster decline in lung function.⁸

Exacerbations may characterize a phenotype of COPD. The Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) analyzed the frequency of COPD exacerbations and associated factors in 2,138 patients with COPD over a period of 3 years.⁹ Although patients with more severe obstruction tended to have more exacerbations, some patients appeared susceptible to exacerbations irrespective of the severity of obstruction. The best predictor of exacerbations was a history of exacerbations.

HOW DO I ASSESS A PATIENT WITH COPD ON PRESENTATION?

Markers of airflow obstruction such as the FEV₁ do not correlate strongly with exertional capacity and health status in patients with COPD.^10,11

The BODE index (body mass index, obstruction, dyspnea score, and exercise oximetry) takes into account the multidimensional nature of COPD. It performs better than the FEV₁ in predicting the risk of death.¹² The propensity for exacerbations and comorbidities further modulates outcome.

Assessing symptoms

The modified British Medical Research Council (mMRC) dyspnea scale, based on work by Fletcher in 1952,¹³ has five grades, numbered 0 through 4:

• Grade 0—Breathless with strenuous exercise only
• Grade 1—Breathless when hurrying on level ground or walking up a slight hill
• Grade 2—Walks slower than people of the same age on level ground because of shortness of breath or has to stop when walking at own pace on level ground
• Grade 3—Stops for breath after walking about 100 yards or after a few minutes on level ground
• Grade 4—Too breathless to leave the house or breathless when dressing or undressing.

Grade 2 or higher separates symptomatic from asymptomatic COPD.

The COPD Assessment Test (CAT) (www.catestonline.org) is a proprietary questionnaire. Patients use a 6-point scale (numbered 0 though 5) to rate eight symptoms (cough, mucus production, chest tightness, shortness of breath on exertion, limitations in home activities, lack of confidence leaving the home, poor sleep, and lack of energy). A total score of 10 or higher is abnormal.

Four GOLD groups

The new GOLD guidelines (Table 1)⁵ define four groups of patients according to their severity of airflow obstruction, symptoms, and exacerbation history:

• Group A—fewer symptoms, low risk: Fewer symptoms (“less symptoms,” as worded in the guidelines) means a CAT score less than 10 or an mMRC grade less than 2; “low risk” means no more than one exacerbation per year and an FEV₁ of at least 50%
• Group B—more symptoms, low risk: “More symptoms” means a CAT score of 10 or more or an mMRC grade of 2 or more
• Group C—fewer symptoms, high risk: “High risk” means two or more exacerbations per year or an FEV₁ less than 50%
• Group D—more symptoms, high risk.

Thus, a patient with an FEV₁ of 60% (moderate airflow limitation) who has had one exacerbation during the past year and a CAT score of 8 would be in group A. In contrast, a patient who has an FEV₁ of 40% (severe airflow limitation), no history of exacerbations, and a CAT score of 20 would be in group D.

Updated GOLD guidelines suggest utilizing a stepwise approach to treatment, akin to asthma management guidelines, based on patient grouping.⁵

How accurate is the new GOLD system?

Although practical and suited for use in primary care, the new GOLD system is arbitrary and has not been thoroughly studied, and may therefore need refinement.

Lange et al¹⁴ compared the new GOLD system with the previous one in 6,628 patients with COPD. As anticipated, the new system was better at predicting exacerbations, as it incorporates a history of exacerbations in stratification. The presence of symptoms (as determined by an mMRC grade ≥ 2) was a marker of mortality risk that distinguished group A from group B, and group C from group D. Surprisingly, the rate of death was higher in group B (more symptoms, low risk) than in group C (fewer symptoms, high risk).

Notably, most patients in group C qualified for this group because of the severity of airflow obstruction, not because of a history of exacerbations. Therefore, patients whose symptoms are out of proportion to the severity of obstruction may be at higher risk of death, possibly because of comorbidities such as cardiovascular disease.¹⁵ Patients who qualified for groups C and D by having both a history of frequent exacerbations (≥ 2 per year) and symptoms rather than either one alone had a higher risk of death in 3 years.

Similarly, the symptom-assessment tool that is used—ie, the mMRC grade or the CAT score—also makes a difference.

The Health-Related Quality of Life in COPD in Europe Study¹⁶ retrospectively analyzed data from 1,817 patients to determine whether the cutoff points for symptoms as assessed by mMRC grade and CAT score were equivalent. Although the mMRC grade correlated well with overall health status, the cutoff mMRC grade of 2 or higher did not correspond to a CAT score of 10 or higher, classifying patients with health status impairment as asymptomatic (mean weighted kappa 0.626). The two tools agreed much better when the cutoff was set at an mMRC grade of 1 or higher (mean weighted kappa 0.792).¹⁶

Although assessment schemes continue to evolve as data accumulate, we believe the new system is a welcome initiative that reflects the changing notions of COPD.

Comorbidities matter

Another shift is the recognition that certain comorbidities increase the risk of death. In 1,664 patients with COPD who were followed for 51 months, 12 distinct comorbidities were associated with a higher risk of death after multivariate analysis.¹⁷

The COTE index (COPD-Specific Comorbidity Test) is based on these findings. It awards points as follows:

• 6 points for cancer of the lung, esophagus, pancreas, or breast, or for anxiety
• 2 points for all other cancers, liver cirrhosis, atrial fibrillation or flutter, diabetes with neuropathy, or pulmonary fibrosis
• 1 point for congestive heart failure, gastric or duodenal ulcer, or coronary artery disease.

A COTE index score of 4 or higher was associated with a risk of death 2.2 times higher in each quartile of the BODE index.

We strongly recommend being aware of comorbidities in COPD patients, particularly when symptoms are out of proportion to the severity of obstruction.

SHOULD I USE ANTIBIOTICS TO TREAT ALL COPD EXACERBATIONS?

Infections are thought to cause more than 80% of acute exacerbations of COPD.

Anthonisen et al,¹⁸ in a landmark trial, found broad-spectrum antibiotics to be most helpful if the patient had at least two of the three cardinal symptoms of COPD exacerbation (ie, shortness of breath, increase in sputum volume, and sputum purulence). Antibiotics decreased the rate of treatment failure and led to a more rapid clinical resolution of exacerbation. However, they did not help patients who had milder exacerbations.

Antibiotics may nevertheless have a role in ambulatory patients with mild to moderate COPD who present with exacerbations characterized by one or more cardinal symptoms.

Llor et al,¹⁹ in a multicenter randomized double-blind placebo-controlled trial in Spain, concluded that amoxicillin clavulanate (Augmentin) led to higher clinical cure rates and longer time to the next exacerbation in these patients. Most of the benefit was in patients with more symptoms, consistent with the results of the study by Anthonisen et al.¹⁸

There is also strong evidence to support the use of antibiotics in addition to systemic corticosteroids in hospitalized patients with acute exacerbations of COPD. A 7-day course of doxycycline (Vibramycin) added to a standard regimen of corticosteroids was associated with higher rates of clinical and microbiological cure on day 10 of the exacerbation.²⁰ In a large retrospective cohort study in 84,621 hospitalized patients with COPD exacerbations, fewer of those who received antibiotics needed mechanical ventilation, died, or were readmitted.²¹ Although sicker patients received antibiotics more frequently, their mortality rate was lower than in those who did not receive antibiotics, who were presumably less sick.

A meta-analysis confirmed the salutary effect of antibiotics in inpatients and particularly those admitted to the intensive care unit.²² Mortality rates and hospital length of stay were not affected in patients who were not in intensive care.

Biomarkers such as procalcitonin might help reduce the unnecessary use of antibiotics. Stolz et al²³ conducted a randomized controlled trial in which they based the decision to give antibiotics on a threshold procalcitonin level of at least 1 μg/L in hospitalized patients with COPD exacerbation. The rate of antibiotic use was reduced by more than 40% in the procalcitonin group without any difference in clinical outcomes, 6-month exacerbation rate, or rehospitalization compared with controls. Nonstandardized procalcitonin assays are a possible barrier to the widespread adoption of this threshold.

Comment. In general, we recommend antibiotics for hospitalized patients with COPD exacerbation and look forward to confirmatory data that support the use of biomarkers. For outpatients, we find the Anthonisen criteria useful for decision-making at the point of care.

ARE THERE ANY NEW INTERVENTIONS TO PREVENT COPD EXACERBATIONS?

Macrolides

Macrolides have a proven role in managing chronic suppurative respiratory diseases such as cystic fibrosis²⁴ and diffuse panbronchiolitis.²⁵ Since they are beneficial at lower doses than those used to treat infection, the mechanism may be anti-inflammatory rather than antimicrobial.

Albert et al²⁶ assigned 1,142 patients who had had a COPD exacerbation within a year before enrollment or who were on home oxygen therapy to receive azithromycin (Zithromax) 250 mg daily or placebo.²⁵ The azithromycin group had fewer acute exacerbations (hazard ratio 0.73, 95% CI 0.63–0.84, P < .001), and more patients in the azithromycin group achieved clinically significant improvements in quality of life, ie, a reduction in the St. George’s Respiratory Questionnaire (SGRQ) score of at least 4 points (43% vs 36%, P = .03). Adverse events that were more common in the azithromycin group were hearing loss (25% vs 20%) and macrolide-resistant strains in nasopharyngeal secretions (81% vs 41%). In subgroup analysis, the benefit in terms of reducing exacerbations was greater in patients over age 65, patients on home oxygen, and patients with moderate or severe obstruction compared with those with very severe obstruction.

Comment. Macrolides are a valuable addition to the agents available for preventing COPD exacerbation (Table 2), but their role is still uncertain. Potential topics of research are whether these drugs have a role in patients already on preventive regimens, whether they would have a greater effect in distinct patient populations (eg, patients who have two or more exacerbations per year), and whether their broader use would lead to a change in the resident flora in the community.

Clinicians should exercise caution in the use of azithromycin in light of recent concern about associated cardiac morbidity and death. All patients should undergo electrocardiography to assess the QTc interval before starting treatment, as in the trial by Albert et al.²⁶

Phosphodiesterase inhibitors

Roflumilast (Daliresp) is an oral phosphodiesterase 4 inhibitor approved for treating exacerbations and symptoms of chronic bronchitis in patients with severe COPD (Table 3). Phosphodiesterase 4, one of the 11 isoforms of the enzyme, is found in immune and inflammatory cells and promotes inflammatory responses. Roflumilast has anti-inflammatory properties but no acute bronchodilatory effect.²⁷ Several phase 3 trials found the compound to have beneficial effects.

Calverley et al²⁸ performed two placebo-controlled double-blind trials in outpatients with the clinical diagnosis of COPD who had chronic cough; increased sputum production; at least one recorded exacerbation requiring corticosteroids or hospitalization, or both; and an FEV₁ of 50% or less. Patients were randomized to receive roflumilast 500 μg once a day (n = 1,537) or placebo (n = 1,554) for 1 year. The rate of moderate to severe exacerbations was 1.17 per year with roflumilast vs 1.37 with placebo (P < .0003). Adverse events were significantly more common with roflumilast and were related to the known side effects of the drug, namely, diarrhea, weight loss, decreased appetite, and nausea.

Fabbri et al²⁹ performed two other placebo-controlled double-blind multicenter trials, studying the combinations of roflumilast with salmeterol (Serevent) and roflumilast with tiotropium (Spiriva) compared with placebo in 1,676 patients with COPD who had post-bronchodilator FEV₁ values of 40% to 70% of predicted. The mean prebronchodilator FEV₁ improved by 49 mL (P < .0001) in the salmeterol-plus-roflumilast trial and by 80 mL (P < .0001) in the tiotropium-plus-roflumilast trial compared with placebo. Fewer patients on roflumilast had exacerbations of any severity in both trials (risk ratio 0.82, P = .0419 and risk ratio 0.75, P = .0169, respectively).

No trial has yet addressed whether roflumilast is better than the combination of a long-acting muscarinic antagonist and a beta agonist, or whether roflumilast can be substituted for inhaled corticosteroids in a new triple-therapy combination. Clinicians should also be aware of psychiatric side effects of roflumilast, which include depression and, possibly, suicide.

ARE THERE ANY NEW BRONCHODILATORS FOR PATIENTS WITH COPD?

Long-acting muscarinic antagonists

Reversible airflow obstruction and mucus secretion are determined by the vagal cholinergic tone in patients with COPD.³⁰ Antagonism of cholinergic (muscarinic) receptors results in bronchodilation and reduction in mucus production. Consequently, inhaled anticholinergic agents are the first-line therapy for COPD (Table 4).

Tiotropium bromide is a long-acting antimuscarinic approved in 2002 by the US Food and Drug Administration (FDA). The UPLIFT trial (Understanding Potential Long-Term Impacts on Function With Tiotropium)³¹ enrolled 5,993 patients with a mean FEV₁ of 48% of predicted. Over a 4-year follow-up, significant improvements in mean FEV₁ values (ranging from 87 mL to 103 mL before bronchodilation and 47 mL to 65 mL after bronchodilation, P < .001) in the tiotropium group were observed compared with placebo. The rate of the primary end point—the rate of decline in mean FEV₁—was not different between tiotropium and placebo. However, there were important salutary effects in multiple clinical end points in the tiotropium group. Health-related quality of life as measured by the SGRQ improved in a clinically significant manner (> 4 points) in favor of tiotropium in a higher proportion of patients (45% vs 36%, P < .001). Tiotropium reduced the number of exacerbations per patient year (0.73 ± 0.02 vs 0.85 ± 0.02, RR = 0.86 (95% CI 0.81–0.91), P < .001) and the risk of respiratory failure (RR = 0.67, 95% CI 0.51–0.89). There were no significant differences in the risk of myocardial infarction, stroke, or pneumonia.

Aclidinium bromide (Tudorza Pressair) is a long-acting antimuscarinic recently approved by the FDA. Compared with tiotropium, it has a slightly faster onset of action and a considerably shorter half-life (29 hours vs 64 hours).^32,33 Its dosage is 400 μg twice daily by inhalation. It provides sustained bronchodilation over 24 hours and may have a favorable side-effect profile, because it undergoes rapid hydrolysis in human plasma.³⁴

ACCORD COPD I³⁵ and ATTAIN,³⁶ two phase 3 trials in patients with moderate-to severe COPD, found that twice-daily aclidinium was associated with statistically and clinically significant (> 100 mL) improvements in trough and peak FEV₁ compared with placebo. Health status (assessed by SGRQ) and dyspnea (assessed by transitional dyspnea index) also improved significantly. However, improvements beyond minimum clinically significant thresholds were achieved only with 400 μg twice-daily dosing.

To date, no study has evaluated the impact of aclidinium on COPD exacerbation as a primary end point. Fewer moderate to severe exacerbations were reported in an earlier 52-week study of once-daily aclidinium (ACCLAIM COPD II) but not in ACCLAIM COPD I.³⁷

Aclidinium may offer an advantage over tiotropium in patients who have nocturnal symptoms. Twice-daily aclidinium 400 μg was associated with superior FEV₁ area-under-the-curve values compared with placebo and tiotropium, the difference mostly owing to improved nocturnal profile.³⁸

Long-acting beta-2 agonists

Stimulation of airway beta-2 receptors relaxes smooth muscles and consequently dilates bronchioles via a cyclic adenosine monophosphate-dependent pathway.³⁹

Short-acting beta-2 agonists such as albuterol and terbutaline have long been used as rescue medications for obstructive lung disease. Long-acting beta-2 agonists provide sustained bronchodilation and are therefore more efficacious as maintenance medications. Salmeterol, formoterol (Foradil), and arformoterol (Brovana) are long-acting beta-2 agonists in clinical use that are taken twice daily.

Clinical studies indicate that use of long-acting beta-2 agonists leads to significant improvements in FEV₁,^40–42 dynamic hyperinflation, exercise tolerance,^43,44 and dyspnea.^45,46 These drugs have also been associated with significant improvements in health-related quality of life and in the frequency of exacerbations.^47–49

In patients with asthma, long-acting beta agonists may increase the risk of death.⁵⁰ In contrast, in patients with COPD, they appear to offer a survival advantage when used in combination with inhaled corticosteroids,⁵¹ and some argue that this benefit is entirely from the long-acting beta agonist (a 17% reduction in mortality) rather than the inhaled corticosteroid (0% reduction in mortality).⁵²

Indacaterol (Arcapta), approved in July 2011, is the first once-daily beta agonist or “ultra-long-acting” beta agonist (Table 5). Possibly because it has a high affinity for the lipid raft domain of the cell membrane where beta-2 receptors are coupled to second messengers,⁵³ the drug has a 24-hour duration of action.

In patients with COPD, inhaled indacaterol 150 μg once daily improved airflow obstruction and health status as measured by SGRQ compared with salmeterol 50 μg twice daily and placebo.⁵⁴ At the higher dose of 300 μg daily, the 52-week INVOLVE trial⁵⁵ demonstrated early and more sustained improvement in FEV₁ compared with placebo and formoterol. In this study, a lower exacerbation rate than with placebo was also noted. The drug has also shown equivalent bronchodilator efficacy at 150 μg and 300 μg daily dosing compared with tiotropium.⁵⁶

The benefits of a longer-acting bronchodilator such as indacaterol are likely mediated by smoothing out airway bronchomotor tone over 24 hours without the dips seen with shorter-acting agents and by improvement of the FEV₁ trough before the subsequent dose is due, aptly named “pharmacologic stenting.”⁵⁷ Once-daily dosing should also foster better adherence. The safety profile appears excellent with no increase in cardiovascular or cerebrovascular events compared with placebo.⁵⁸

The FDA approved the 75-μg daily dose instead of the higher doses used in the studies mentioned above. This decision was based on the observation that there appeared to be a flattened dose-response in patients with more severe COPD, with no further improvement in trough FEV₁ at higher doses.⁵⁹

DOES VITAMIN D SUPPLEMENTATION HAVE A ROLE IN COPD MANAGEMENT?

Vitamin D is vital for calcium and phosphate metabolism and bone health. Low vitamin D levels are associated with diminished leg strength and falls in the elderly.⁶⁰ Osteoporosis, preventable with vitamin D and calcium supplementation, is linked to thoracic vertebral fracture and consequent reduced lung function.^61,62

Patients with COPD are at higher risk of vitamin D deficiency, and more so if they also are obese, have advanced airflow obstruction, are depressed, or smoke.⁶² Therefore, there are sound reasons to look for vitamin D deficiency in patients with COPD and to treat it if the 25-hydroxyvitamin D level is less than 10 ng/ mL (Table 6).

Vitamin D may also have antimicrobial and immunomodulatory effects.⁶³ Since COPD exacerbations are frequently caused by infection, it was hypothesized that vitamin D supplementation might reduce the rate of exacerbations.

In a study in 182 patients with moderate to very severe COPD and a history of recent exacerbations, high-dose vitamin D supplementation (100,000 IU) was given every 4 weeks for 1 year.⁶⁴ There were no differences in the time to first exacerbation, in the rate of exacerbation, hospitalization, or death, or in quality of life between the placebo and intervention groups. However, subgroup analysis indicated that, in those with severe vitamin D deficiency at baseline, the exacerbation rate was reduced by more than 40%.

Comment. We recommend screening for vitamin D deficiency in patients with COPD. Supplementation is appropriate in those with low levels, but data indicate no role in those with normal levels.

WHAT ARE THE NONPHARMACOLOGIC APPROACHES TO COPD TREATMENT?

Noninvasive positive-pressure ventilation

Nocturnal noninvasive positive-pressure ventilation may be beneficial in patients with severe COPD, daytime hypercapnia, and nocturnal hypoventilation, particularly if higher inspiratory pressures are selected (Table 7).^65,66

For instance, a randomized controlled trial of noninvasive positive-pressure ventilation plus long-term oxygen therapy compared with long-term oxygen therapy alone in hypercapnic COPD demonstrated a survival benefit in favor of ventilation (hazard ratio 0.6).⁶⁷

In another randomized trial,⁶⁸ settings that aimed to maximally reduce Paco₂ (mean inspiratory positive airway pressure 29 cm H₂O with a backup rate of 17.5/min) were compared with low-intensity positive airway pressure (mean inspiratory positive airway pressure 14 cm H₂O, backup rate 8/min). The high inspiratory pressures increased the daily use of ventilation by 3.6 hours per day and improved exercise-related dyspnea, daytime Paco₂, FEV₁, vital capacity, and health-related quality of life⁶⁶ without disrupting sleep quality.⁶⁸

Caveats are that acclimation to the high pressures was achieved in the hospital, and the high pressures were associated with a significant increase in air leaks.⁶⁶

Comments. Whether high-pressure noninvasive positive-pressure ventilation can be routinely implemented and adopted in the outpatient setting, and whether it is associated with a survival advantage remains to be determined. The advantages of noninvasive positive-pressure ventilation in the setting of hypercapnic COPD appear to augment those of pulmonary rehabilitation, with improved quality of life, gas exchange, and exercise tolerance, and a slower decline of lung function.⁶⁹

Pulmonary rehabilitation

Pulmonary rehabilitation is a multidisciplinary approach to managing COPD (Table 8).

Patients participate in three to five supervised sessions per week, each lasting 3 to 4 hours, for 6 to 12 weeks. Less-frequent sessions may not be effective. For instance, in a randomized trial, exercising twice a week was not enough.⁷⁰ Additionally, a program lasting longer than 12 weeks produced more sustained benefits than shorter programs.⁷¹

A key component is an exercise protocol centered on the lower extremities (walking, cycling, treadmill), with progressive exercise intensity to a target of about 60% to 80% of the maximal exercise tolerance,⁷² though more modest targets of about 50% can also be beneficial.⁷³

Exercise should be tailored to the desired outcome. For instance, training of the upper arms may help with activities of daily living. In one study, unsupported (against gravity) arm training improved upper-extremity function more than supported arm training (by ergometer).⁷⁴ Ventilatory muscle training is less common, as most randomized trials have not shown conclusive evidence of benefit. Current guidelines do not recommend routine inspiratory muscle training.⁷¹

Even though indices of pulmonary function do not improve after an exercise program, randomized trials have shown that pulmonary rehabilitation improves exercise capacity, dyspnea, and health-related quality of life; improves cost-effectiveness of health care utilization; and provides psychosocial benefits that often exceed those of other therapies. Although there is no significant evidence of whether pulmonary rehabilitation improves survival in patients with COPD,⁷¹ an observational study documented improvements in BODE scores as well as a reduction in respiratory mortality rates in patients undergoing pulmonary rehabilitation.⁷⁵

A limitation of pulmonary rehabilitation is that endurance and psychological and cognitive function decline significantly if exercise is not maintained. However, the role of a maintenance program is uncertain, with long-term benefits considered modest.⁷¹

Lung-volume reduction surgery

Lung-volume reduction consists of surgical wedge resections of emphysematous areas of the lung (Table 9).

The National Emphysema Treatment Trial⁷⁶ randomized 1,218 patients to undergo either lung-volume reduction surgery or maximal medical therapy. Surgery improved survival, quality of life, and dyspnea in patients with upper-lobe emphysema and a low exercise capacity (corresponding to < 40 watts for men or < 25 watts for women in the maximal power achieved on cycle ergometry). While conferring no survival benefit in patients with upper-lobe-predominant emphysema and high exercise capacity, this surgery is likely to improve exercise capacity and quality of life in this subset of patients.

Importantly, the procedure is associated with a lower survival rate in patients with an FEV₁ lower than 20%, homogeneous emphysema, a diffusing capacity of the lung for carbon monoxide lower than 20%, non-upper-lobe emphysema, or high baseline exercise capacity.

The proposed mechanisms of improvement of lung function include placing the diaphragm in a position with better mechanical advantage, reducing overall lung volume, better size-matching between the lungs and chest cavity, and restoring elastic recoil.^76,77

Ongoing trials aim to replicate the success of lung-volume reduction using nonsurgical bronchoscopic techniques with one-way valves, coils, biologic sealants, thermal ablation, and airway stents.

Chronic obstructive pulmonary disease (COPD) has seen several changes in its assessment and treatment in recent years, reflecting advances in our understanding of this common and serious disease.

This review updates busy practitioners on the major advances, including new assessment tools and new therapies.

COMMON AND INCREASING

COPD is the third leading cause of death in the United States, behind heart disease and cancer,¹ and of the top five (the others being stroke and accidents), it is the only one that increased in incidence between 2007 and 2010.² The 11th leading cause of disability-adjusted life years worldwide in 2002, COPD is projected to become the seventh by the year 2030.³

CHARACTERIZED BY OBSTRUCTION

COPD is characterized by persistent and progressive airflow obstruction associated with chronic airway inflammation in response to noxious particles and gases. Disease of the small airways (inflammation, mucus plugging, and fibrosis) and parenchymal destruction (emphysema) limit the flow of air.

COPD is diagnosed by spirometry—specifically, a ratio of forced expiratory volume in 1 second to forced vital capacity (FEV₁/FVC) of less than 0.7 after a bronchodilator is given. The severity of airflow limitation is revealed by the FEV₁ as a percent of the predicted value.

Cigarette smoking is the major cause of COPD, but the prevalence of COPD is 6.6% in people who have never smoked, and one-fourth of COPD patients in the United States have never smoked.⁴

GOLDEN GOALS: FEWER SYMPTOMS, LOWER RISK

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) periodically issues evidence-based statements on how to prevent and treat COPD.

In its 2013 update,⁵ GOLD suggested two goals: improving symptoms and reducing the risk of death, exacerbations, progression of disease, and treatment-related adverse effects. The latter goal—reducing risk—is relatively new.

Exacerbations are acute inflammatory events superimposed on chronic inflammation. The inflammation is often brought on by infection⁶ and increases the risk of death⁷ and the risk of a faster decline in lung function.⁸

Exacerbations may characterize a phenotype of COPD. The Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) analyzed the frequency of COPD exacerbations and associated factors in 2,138 patients with COPD over a period of 3 years.⁹ Although patients with more severe obstruction tended to have more exacerbations, some patients appeared susceptible to exacerbations irrespective of the severity of obstruction. The best predictor of exacerbations was a history of exacerbations.

HOW DO I ASSESS A PATIENT WITH COPD ON PRESENTATION?

Markers of airflow obstruction such as the FEV₁ do not correlate strongly with exertional capacity and health status in patients with COPD.^10,11

The BODE index (body mass index, obstruction, dyspnea score, and exercise oximetry) takes into account the multidimensional nature of COPD. It performs better than the FEV₁ in predicting the risk of death.¹² The propensity for exacerbations and comorbidities further modulates outcome.

Assessing symptoms

The modified British Medical Research Council (mMRC) dyspnea scale, based on work by Fletcher in 1952,¹³ has five grades, numbered 0 through 4:

• Grade 0—Breathless with strenuous exercise only
• Grade 1—Breathless when hurrying on level ground or walking up a slight hill
• Grade 2—Walks slower than people of the same age on level ground because of shortness of breath or has to stop when walking at own pace on level ground
• Grade 3—Stops for breath after walking about 100 yards or after a few minutes on level ground
• Grade 4—Too breathless to leave the house or breathless when dressing or undressing.

Grade 2 or higher separates symptomatic from asymptomatic COPD.

The COPD Assessment Test (CAT) (www.catestonline.org) is a proprietary questionnaire. Patients use a 6-point scale (numbered 0 though 5) to rate eight symptoms (cough, mucus production, chest tightness, shortness of breath on exertion, limitations in home activities, lack of confidence leaving the home, poor sleep, and lack of energy). A total score of 10 or higher is abnormal.

Four GOLD groups

The new GOLD guidelines (Table 1)⁵ define four groups of patients according to their severity of airflow obstruction, symptoms, and exacerbation history:

• Group A—fewer symptoms, low risk: Fewer symptoms (“less symptoms,” as worded in the guidelines) means a CAT score less than 10 or an mMRC grade less than 2; “low risk” means no more than one exacerbation per year and an FEV₁ of at least 50%
• Group B—more symptoms, low risk: “More symptoms” means a CAT score of 10 or more or an mMRC grade of 2 or more
• Group C—fewer symptoms, high risk: “High risk” means two or more exacerbations per year or an FEV₁ less than 50%
• Group D—more symptoms, high risk.

Thus, a patient with an FEV₁ of 60% (moderate airflow limitation) who has had one exacerbation during the past year and a CAT score of 8 would be in group A. In contrast, a patient who has an FEV₁ of 40% (severe airflow limitation), no history of exacerbations, and a CAT score of 20 would be in group D.

Updated GOLD guidelines suggest utilizing a stepwise approach to treatment, akin to asthma management guidelines, based on patient grouping.⁵

How accurate is the new GOLD system?

Although practical and suited for use in primary care, the new GOLD system is arbitrary and has not been thoroughly studied, and may therefore need refinement.

Lange et al¹⁴ compared the new GOLD system with the previous one in 6,628 patients with COPD. As anticipated, the new system was better at predicting exacerbations, as it incorporates a history of exacerbations in stratification. The presence of symptoms (as determined by an mMRC grade ≥ 2) was a marker of mortality risk that distinguished group A from group B, and group C from group D. Surprisingly, the rate of death was higher in group B (more symptoms, low risk) than in group C (fewer symptoms, high risk).

Notably, most patients in group C qualified for this group because of the severity of airflow obstruction, not because of a history of exacerbations. Therefore, patients whose symptoms are out of proportion to the severity of obstruction may be at higher risk of death, possibly because of comorbidities such as cardiovascular disease.¹⁵ Patients who qualified for groups C and D by having both a history of frequent exacerbations (≥ 2 per year) and symptoms rather than either one alone had a higher risk of death in 3 years.

Similarly, the symptom-assessment tool that is used—ie, the mMRC grade or the CAT score—also makes a difference.

The Health-Related Quality of Life in COPD in Europe Study¹⁶ retrospectively analyzed data from 1,817 patients to determine whether the cutoff points for symptoms as assessed by mMRC grade and CAT score were equivalent. Although the mMRC grade correlated well with overall health status, the cutoff mMRC grade of 2 or higher did not correspond to a CAT score of 10 or higher, classifying patients with health status impairment as asymptomatic (mean weighted kappa 0.626). The two tools agreed much better when the cutoff was set at an mMRC grade of 1 or higher (mean weighted kappa 0.792).¹⁶

Although assessment schemes continue to evolve as data accumulate, we believe the new system is a welcome initiative that reflects the changing notions of COPD.

Comorbidities matter

Another shift is the recognition that certain comorbidities increase the risk of death. In 1,664 patients with COPD who were followed for 51 months, 12 distinct comorbidities were associated with a higher risk of death after multivariate analysis.¹⁷

The COTE index (COPD-Specific Comorbidity Test) is based on these findings. It awards points as follows:

• 6 points for cancer of the lung, esophagus, pancreas, or breast, or for anxiety
• 2 points for all other cancers, liver cirrhosis, atrial fibrillation or flutter, diabetes with neuropathy, or pulmonary fibrosis
• 1 point for congestive heart failure, gastric or duodenal ulcer, or coronary artery disease.

A COTE index score of 4 or higher was associated with a risk of death 2.2 times higher in each quartile of the BODE index.

We strongly recommend being aware of comorbidities in COPD patients, particularly when symptoms are out of proportion to the severity of obstruction.

SHOULD I USE ANTIBIOTICS TO TREAT ALL COPD EXACERBATIONS?

Infections are thought to cause more than 80% of acute exacerbations of COPD.

Anthonisen et al,¹⁸ in a landmark trial, found broad-spectrum antibiotics to be most helpful if the patient had at least two of the three cardinal symptoms of COPD exacerbation (ie, shortness of breath, increase in sputum volume, and sputum purulence). Antibiotics decreased the rate of treatment failure and led to a more rapid clinical resolution of exacerbation. However, they did not help patients who had milder exacerbations.

Antibiotics may nevertheless have a role in ambulatory patients with mild to moderate COPD who present with exacerbations characterized by one or more cardinal symptoms.

Llor et al,¹⁹ in a multicenter randomized double-blind placebo-controlled trial in Spain, concluded that amoxicillin clavulanate (Augmentin) led to higher clinical cure rates and longer time to the next exacerbation in these patients. Most of the benefit was in patients with more symptoms, consistent with the results of the study by Anthonisen et al.¹⁸

There is also strong evidence to support the use of antibiotics in addition to systemic corticosteroids in hospitalized patients with acute exacerbations of COPD. A 7-day course of doxycycline (Vibramycin) added to a standard regimen of corticosteroids was associated with higher rates of clinical and microbiological cure on day 10 of the exacerbation.²⁰ In a large retrospective cohort study in 84,621 hospitalized patients with COPD exacerbations, fewer of those who received antibiotics needed mechanical ventilation, died, or were readmitted.²¹ Although sicker patients received antibiotics more frequently, their mortality rate was lower than in those who did not receive antibiotics, who were presumably less sick.

A meta-analysis confirmed the salutary effect of antibiotics in inpatients and particularly those admitted to the intensive care unit.²² Mortality rates and hospital length of stay were not affected in patients who were not in intensive care.

Biomarkers such as procalcitonin might help reduce the unnecessary use of antibiotics. Stolz et al²³ conducted a randomized controlled trial in which they based the decision to give antibiotics on a threshold procalcitonin level of at least 1 μg/L in hospitalized patients with COPD exacerbation. The rate of antibiotic use was reduced by more than 40% in the procalcitonin group without any difference in clinical outcomes, 6-month exacerbation rate, or rehospitalization compared with controls. Nonstandardized procalcitonin assays are a possible barrier to the widespread adoption of this threshold.

Comment. In general, we recommend antibiotics for hospitalized patients with COPD exacerbation and look forward to confirmatory data that support the use of biomarkers. For outpatients, we find the Anthonisen criteria useful for decision-making at the point of care.

ARE THERE ANY NEW INTERVENTIONS TO PREVENT COPD EXACERBATIONS?

Macrolides

Macrolides have a proven role in managing chronic suppurative respiratory diseases such as cystic fibrosis²⁴ and diffuse panbronchiolitis.²⁵ Since they are beneficial at lower doses than those used to treat infection, the mechanism may be anti-inflammatory rather than antimicrobial.

Albert et al²⁶ assigned 1,142 patients who had had a COPD exacerbation within a year before enrollment or who were on home oxygen therapy to receive azithromycin (Zithromax) 250 mg daily or placebo.²⁵ The azithromycin group had fewer acute exacerbations (hazard ratio 0.73, 95% CI 0.63–0.84, P < .001), and more patients in the azithromycin group achieved clinically significant improvements in quality of life, ie, a reduction in the St. George’s Respiratory Questionnaire (SGRQ) score of at least 4 points (43% vs 36%, P = .03). Adverse events that were more common in the azithromycin group were hearing loss (25% vs 20%) and macrolide-resistant strains in nasopharyngeal secretions (81% vs 41%). In subgroup analysis, the benefit in terms of reducing exacerbations was greater in patients over age 65, patients on home oxygen, and patients with moderate or severe obstruction compared with those with very severe obstruction.

Comment. Macrolides are a valuable addition to the agents available for preventing COPD exacerbation (Table 2), but their role is still uncertain. Potential topics of research are whether these drugs have a role in patients already on preventive regimens, whether they would have a greater effect in distinct patient populations (eg, patients who have two or more exacerbations per year), and whether their broader use would lead to a change in the resident flora in the community.

Clinicians should exercise caution in the use of azithromycin in light of recent concern about associated cardiac morbidity and death. All patients should undergo electrocardiography to assess the QTc interval before starting treatment, as in the trial by Albert et al.²⁶

Phosphodiesterase inhibitors

Roflumilast (Daliresp) is an oral phosphodiesterase 4 inhibitor approved for treating exacerbations and symptoms of chronic bronchitis in patients with severe COPD (Table 3). Phosphodiesterase 4, one of the 11 isoforms of the enzyme, is found in immune and inflammatory cells and promotes inflammatory responses. Roflumilast has anti-inflammatory properties but no acute bronchodilatory effect.²⁷ Several phase 3 trials found the compound to have beneficial effects.

Calverley et al²⁸ performed two placebo-controlled double-blind trials in outpatients with the clinical diagnosis of COPD who had chronic cough; increased sputum production; at least one recorded exacerbation requiring corticosteroids or hospitalization, or both; and an FEV₁ of 50% or less. Patients were randomized to receive roflumilast 500 μg once a day (n = 1,537) or placebo (n = 1,554) for 1 year. The rate of moderate to severe exacerbations was 1.17 per year with roflumilast vs 1.37 with placebo (P < .0003). Adverse events were significantly more common with roflumilast and were related to the known side effects of the drug, namely, diarrhea, weight loss, decreased appetite, and nausea.

Fabbri et al²⁹ performed two other placebo-controlled double-blind multicenter trials, studying the combinations of roflumilast with salmeterol (Serevent) and roflumilast with tiotropium (Spiriva) compared with placebo in 1,676 patients with COPD who had post-bronchodilator FEV₁ values of 40% to 70% of predicted. The mean prebronchodilator FEV₁ improved by 49 mL (P < .0001) in the salmeterol-plus-roflumilast trial and by 80 mL (P < .0001) in the tiotropium-plus-roflumilast trial compared with placebo. Fewer patients on roflumilast had exacerbations of any severity in both trials (risk ratio 0.82, P = .0419 and risk ratio 0.75, P = .0169, respectively).

No trial has yet addressed whether roflumilast is better than the combination of a long-acting muscarinic antagonist and a beta agonist, or whether roflumilast can be substituted for inhaled corticosteroids in a new triple-therapy combination. Clinicians should also be aware of psychiatric side effects of roflumilast, which include depression and, possibly, suicide.

ARE THERE ANY NEW BRONCHODILATORS FOR PATIENTS WITH COPD?

Long-acting muscarinic antagonists

Reversible airflow obstruction and mucus secretion are determined by the vagal cholinergic tone in patients with COPD.³⁰ Antagonism of cholinergic (muscarinic) receptors results in bronchodilation and reduction in mucus production. Consequently, inhaled anticholinergic agents are the first-line therapy for COPD (Table 4).

Tiotropium bromide is a long-acting antimuscarinic approved in 2002 by the US Food and Drug Administration (FDA). The UPLIFT trial (Understanding Potential Long-Term Impacts on Function With Tiotropium)³¹ enrolled 5,993 patients with a mean FEV₁ of 48% of predicted. Over a 4-year follow-up, significant improvements in mean FEV₁ values (ranging from 87 mL to 103 mL before bronchodilation and 47 mL to 65 mL after bronchodilation, P < .001) in the tiotropium group were observed compared with placebo. The rate of the primary end point—the rate of decline in mean FEV₁—was not different between tiotropium and placebo. However, there were important salutary effects in multiple clinical end points in the tiotropium group. Health-related quality of life as measured by the SGRQ improved in a clinically significant manner (> 4 points) in favor of tiotropium in a higher proportion of patients (45% vs 36%, P < .001). Tiotropium reduced the number of exacerbations per patient year (0.73 ± 0.02 vs 0.85 ± 0.02, RR = 0.86 (95% CI 0.81–0.91), P < .001) and the risk of respiratory failure (RR = 0.67, 95% CI 0.51–0.89). There were no significant differences in the risk of myocardial infarction, stroke, or pneumonia.

Aclidinium bromide (Tudorza Pressair) is a long-acting antimuscarinic recently approved by the FDA. Compared with tiotropium, it has a slightly faster onset of action and a considerably shorter half-life (29 hours vs 64 hours).^32,33 Its dosage is 400 μg twice daily by inhalation. It provides sustained bronchodilation over 24 hours and may have a favorable side-effect profile, because it undergoes rapid hydrolysis in human plasma.³⁴

ACCORD COPD I³⁵ and ATTAIN,³⁶ two phase 3 trials in patients with moderate-to severe COPD, found that twice-daily aclidinium was associated with statistically and clinically significant (> 100 mL) improvements in trough and peak FEV₁ compared with placebo. Health status (assessed by SGRQ) and dyspnea (assessed by transitional dyspnea index) also improved significantly. However, improvements beyond minimum clinically significant thresholds were achieved only with 400 μg twice-daily dosing.

To date, no study has evaluated the impact of aclidinium on COPD exacerbation as a primary end point. Fewer moderate to severe exacerbations were reported in an earlier 52-week study of once-daily aclidinium (ACCLAIM COPD II) but not in ACCLAIM COPD I.³⁷

Aclidinium may offer an advantage over tiotropium in patients who have nocturnal symptoms. Twice-daily aclidinium 400 μg was associated with superior FEV₁ area-under-the-curve values compared with placebo and tiotropium, the difference mostly owing to improved nocturnal profile.³⁸

Long-acting beta-2 agonists

Stimulation of airway beta-2 receptors relaxes smooth muscles and consequently dilates bronchioles via a cyclic adenosine monophosphate-dependent pathway.³⁹

Short-acting beta-2 agonists such as albuterol and terbutaline have long been used as rescue medications for obstructive lung disease. Long-acting beta-2 agonists provide sustained bronchodilation and are therefore more efficacious as maintenance medications. Salmeterol, formoterol (Foradil), and arformoterol (Brovana) are long-acting beta-2 agonists in clinical use that are taken twice daily.

Clinical studies indicate that use of long-acting beta-2 agonists leads to significant improvements in FEV₁,^40–42 dynamic hyperinflation, exercise tolerance,^43,44 and dyspnea.^45,46 These drugs have also been associated with significant improvements in health-related quality of life and in the frequency of exacerbations.^47–49

In patients with asthma, long-acting beta agonists may increase the risk of death.⁵⁰ In contrast, in patients with COPD, they appear to offer a survival advantage when used in combination with inhaled corticosteroids,⁵¹ and some argue that this benefit is entirely from the long-acting beta agonist (a 17% reduction in mortality) rather than the inhaled corticosteroid (0% reduction in mortality).⁵²

Indacaterol (Arcapta), approved in July 2011, is the first once-daily beta agonist or “ultra-long-acting” beta agonist (Table 5). Possibly because it has a high affinity for the lipid raft domain of the cell membrane where beta-2 receptors are coupled to second messengers,⁵³ the drug has a 24-hour duration of action.

In patients with COPD, inhaled indacaterol 150 μg once daily improved airflow obstruction and health status as measured by SGRQ compared with salmeterol 50 μg twice daily and placebo.⁵⁴ At the higher dose of 300 μg daily, the 52-week INVOLVE trial⁵⁵ demonstrated early and more sustained improvement in FEV₁ compared with placebo and formoterol. In this study, a lower exacerbation rate than with placebo was also noted. The drug has also shown equivalent bronchodilator efficacy at 150 μg and 300 μg daily dosing compared with tiotropium.⁵⁶

The benefits of a longer-acting bronchodilator such as indacaterol are likely mediated by smoothing out airway bronchomotor tone over 24 hours without the dips seen with shorter-acting agents and by improvement of the FEV₁ trough before the subsequent dose is due, aptly named “pharmacologic stenting.”⁵⁷ Once-daily dosing should also foster better adherence. The safety profile appears excellent with no increase in cardiovascular or cerebrovascular events compared with placebo.⁵⁸

The FDA approved the 75-μg daily dose instead of the higher doses used in the studies mentioned above. This decision was based on the observation that there appeared to be a flattened dose-response in patients with more severe COPD, with no further improvement in trough FEV₁ at higher doses.⁵⁹

DOES VITAMIN D SUPPLEMENTATION HAVE A ROLE IN COPD MANAGEMENT?

Vitamin D is vital for calcium and phosphate metabolism and bone health. Low vitamin D levels are associated with diminished leg strength and falls in the elderly.⁶⁰ Osteoporosis, preventable with vitamin D and calcium supplementation, is linked to thoracic vertebral fracture and consequent reduced lung function.^61,62

Patients with COPD are at higher risk of vitamin D deficiency, and more so if they also are obese, have advanced airflow obstruction, are depressed, or smoke.⁶² Therefore, there are sound reasons to look for vitamin D deficiency in patients with COPD and to treat it if the 25-hydroxyvitamin D level is less than 10 ng/ mL (Table 6).

Vitamin D may also have antimicrobial and immunomodulatory effects.⁶³ Since COPD exacerbations are frequently caused by infection, it was hypothesized that vitamin D supplementation might reduce the rate of exacerbations.

In a study in 182 patients with moderate to very severe COPD and a history of recent exacerbations, high-dose vitamin D supplementation (100,000 IU) was given every 4 weeks for 1 year.⁶⁴ There were no differences in the time to first exacerbation, in the rate of exacerbation, hospitalization, or death, or in quality of life between the placebo and intervention groups. However, subgroup analysis indicated that, in those with severe vitamin D deficiency at baseline, the exacerbation rate was reduced by more than 40%.

Comment. We recommend screening for vitamin D deficiency in patients with COPD. Supplementation is appropriate in those with low levels, but data indicate no role in those with normal levels.

WHAT ARE THE NONPHARMACOLOGIC APPROACHES TO COPD TREATMENT?

Noninvasive positive-pressure ventilation

Nocturnal noninvasive positive-pressure ventilation may be beneficial in patients with severe COPD, daytime hypercapnia, and nocturnal hypoventilation, particularly if higher inspiratory pressures are selected (Table 7).^65,66

For instance, a randomized controlled trial of noninvasive positive-pressure ventilation plus long-term oxygen therapy compared with long-term oxygen therapy alone in hypercapnic COPD demonstrated a survival benefit in favor of ventilation (hazard ratio 0.6).⁶⁷

In another randomized trial,⁶⁸ settings that aimed to maximally reduce Paco₂ (mean inspiratory positive airway pressure 29 cm H₂O with a backup rate of 17.5/min) were compared with low-intensity positive airway pressure (mean inspiratory positive airway pressure 14 cm H₂O, backup rate 8/min). The high inspiratory pressures increased the daily use of ventilation by 3.6 hours per day and improved exercise-related dyspnea, daytime Paco₂, FEV₁, vital capacity, and health-related quality of life⁶⁶ without disrupting sleep quality.⁶⁸

Caveats are that acclimation to the high pressures was achieved in the hospital, and the high pressures were associated with a significant increase in air leaks.⁶⁶

Comments. Whether high-pressure noninvasive positive-pressure ventilation can be routinely implemented and adopted in the outpatient setting, and whether it is associated with a survival advantage remains to be determined. The advantages of noninvasive positive-pressure ventilation in the setting of hypercapnic COPD appear to augment those of pulmonary rehabilitation, with improved quality of life, gas exchange, and exercise tolerance, and a slower decline of lung function.⁶⁹

Pulmonary rehabilitation

Pulmonary rehabilitation is a multidisciplinary approach to managing COPD (Table 8).

Patients participate in three to five supervised sessions per week, each lasting 3 to 4 hours, for 6 to 12 weeks. Less-frequent sessions may not be effective. For instance, in a randomized trial, exercising twice a week was not enough.⁷⁰ Additionally, a program lasting longer than 12 weeks produced more sustained benefits than shorter programs.⁷¹

A key component is an exercise protocol centered on the lower extremities (walking, cycling, treadmill), with progressive exercise intensity to a target of about 60% to 80% of the maximal exercise tolerance,⁷² though more modest targets of about 50% can also be beneficial.⁷³

Exercise should be tailored to the desired outcome. For instance, training of the upper arms may help with activities of daily living. In one study, unsupported (against gravity) arm training improved upper-extremity function more than supported arm training (by ergometer).⁷⁴ Ventilatory muscle training is less common, as most randomized trials have not shown conclusive evidence of benefit. Current guidelines do not recommend routine inspiratory muscle training.⁷¹

Even though indices of pulmonary function do not improve after an exercise program, randomized trials have shown that pulmonary rehabilitation improves exercise capacity, dyspnea, and health-related quality of life; improves cost-effectiveness of health care utilization; and provides psychosocial benefits that often exceed those of other therapies. Although there is no significant evidence of whether pulmonary rehabilitation improves survival in patients with COPD,⁷¹ an observational study documented improvements in BODE scores as well as a reduction in respiratory mortality rates in patients undergoing pulmonary rehabilitation.⁷⁵

A limitation of pulmonary rehabilitation is that endurance and psychological and cognitive function decline significantly if exercise is not maintained. However, the role of a maintenance program is uncertain, with long-term benefits considered modest.⁷¹

Lung-volume reduction surgery

Lung-volume reduction consists of surgical wedge resections of emphysematous areas of the lung (Table 9).

The National Emphysema Treatment Trial⁷⁶ randomized 1,218 patients to undergo either lung-volume reduction surgery or maximal medical therapy. Surgery improved survival, quality of life, and dyspnea in patients with upper-lobe emphysema and a low exercise capacity (corresponding to < 40 watts for men or < 25 watts for women in the maximal power achieved on cycle ergometry). While conferring no survival benefit in patients with upper-lobe-predominant emphysema and high exercise capacity, this surgery is likely to improve exercise capacity and quality of life in this subset of patients.

Importantly, the procedure is associated with a lower survival rate in patients with an FEV₁ lower than 20%, homogeneous emphysema, a diffusing capacity of the lung for carbon monoxide lower than 20%, non-upper-lobe emphysema, or high baseline exercise capacity.

The proposed mechanisms of improvement of lung function include placing the diaphragm in a position with better mechanical advantage, reducing overall lung volume, better size-matching between the lungs and chest cavity, and restoring elastic recoil.^76,77

Ongoing trials aim to replicate the success of lung-volume reduction using nonsurgical bronchoscopic techniques with one-way valves, coils, biologic sealants, thermal ablation, and airway stents.

Chronic obstructive pulmonary disease (COPD) has seen several changes in its assessment and treatment in recent years, reflecting advances in our understanding of this common and serious disease.

This review updates busy practitioners on the major advances, including new assessment tools and new therapies.

COMMON AND INCREASING

COPD is the third leading cause of death in the United States, behind heart disease and cancer,¹ and of the top five (the others being stroke and accidents), it is the only one that increased in incidence between 2007 and 2010.² The 11th leading cause of disability-adjusted life years worldwide in 2002, COPD is projected to become the seventh by the year 2030.³

CHARACTERIZED BY OBSTRUCTION

COPD is characterized by persistent and progressive airflow obstruction associated with chronic airway inflammation in response to noxious particles and gases. Disease of the small airways (inflammation, mucus plugging, and fibrosis) and parenchymal destruction (emphysema) limit the flow of air.

COPD is diagnosed by spirometry—specifically, a ratio of forced expiratory volume in 1 second to forced vital capacity (FEV₁/FVC) of less than 0.7 after a bronchodilator is given. The severity of airflow limitation is revealed by the FEV₁ as a percent of the predicted value.

Cigarette smoking is the major cause of COPD, but the prevalence of COPD is 6.6% in people who have never smoked, and one-fourth of COPD patients in the United States have never smoked.⁴

GOLDEN GOALS: FEWER SYMPTOMS, LOWER RISK

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) periodically issues evidence-based statements on how to prevent and treat COPD.

In its 2013 update,⁵ GOLD suggested two goals: improving symptoms and reducing the risk of death, exacerbations, progression of disease, and treatment-related adverse effects. The latter goal—reducing risk—is relatively new.

Exacerbations are acute inflammatory events superimposed on chronic inflammation. The inflammation is often brought on by infection⁶ and increases the risk of death⁷ and the risk of a faster decline in lung function.⁸

Exacerbations may characterize a phenotype of COPD. The Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) analyzed the frequency of COPD exacerbations and associated factors in 2,138 patients with COPD over a period of 3 years.⁹ Although patients with more severe obstruction tended to have more exacerbations, some patients appeared susceptible to exacerbations irrespective of the severity of obstruction. The best predictor of exacerbations was a history of exacerbations.

HOW DO I ASSESS A PATIENT WITH COPD ON PRESENTATION?

Markers of airflow obstruction such as the FEV₁ do not correlate strongly with exertional capacity and health status in patients with COPD.^10,11

The BODE index (body mass index, obstruction, dyspnea score, and exercise oximetry) takes into account the multidimensional nature of COPD. It performs better than the FEV₁ in predicting the risk of death.¹² The propensity for exacerbations and comorbidities further modulates outcome.

Assessing symptoms

The modified British Medical Research Council (mMRC) dyspnea scale, based on work by Fletcher in 1952,¹³ has five grades, numbered 0 through 4:

• Grade 0—Breathless with strenuous exercise only
• Grade 1—Breathless when hurrying on level ground or walking up a slight hill
• Grade 2—Walks slower than people of the same age on level ground because of shortness of breath or has to stop when walking at own pace on level ground
• Grade 3—Stops for breath after walking about 100 yards or after a few minutes on level ground
• Grade 4—Too breathless to leave the house or breathless when dressing or undressing.

Grade 2 or higher separates symptomatic from asymptomatic COPD.

The COPD Assessment Test (CAT) (www.catestonline.org) is a proprietary questionnaire. Patients use a 6-point scale (numbered 0 though 5) to rate eight symptoms (cough, mucus production, chest tightness, shortness of breath on exertion, limitations in home activities, lack of confidence leaving the home, poor sleep, and lack of energy). A total score of 10 or higher is abnormal.

Four GOLD groups

The new GOLD guidelines (Table 1)⁵ define four groups of patients according to their severity of airflow obstruction, symptoms, and exacerbation history:

• Group A—fewer symptoms, low risk: Fewer symptoms (“less symptoms,” as worded in the guidelines) means a CAT score less than 10 or an mMRC grade less than 2; “low risk” means no more than one exacerbation per year and an FEV₁ of at least 50%
• Group B—more symptoms, low risk: “More symptoms” means a CAT score of 10 or more or an mMRC grade of 2 or more
• Group C—fewer symptoms, high risk: “High risk” means two or more exacerbations per year or an FEV₁ less than 50%
• Group D—more symptoms, high risk.

Thus, a patient with an FEV₁ of 60% (moderate airflow limitation) who has had one exacerbation during the past year and a CAT score of 8 would be in group A. In contrast, a patient who has an FEV₁ of 40% (severe airflow limitation), no history of exacerbations, and a CAT score of 20 would be in group D.

Updated GOLD guidelines suggest utilizing a stepwise approach to treatment, akin to asthma management guidelines, based on patient grouping.⁵

How accurate is the new GOLD system?

Although practical and suited for use in primary care, the new GOLD system is arbitrary and has not been thoroughly studied, and may therefore need refinement.

Lange et al¹⁴ compared the new GOLD system with the previous one in 6,628 patients with COPD. As anticipated, the new system was better at predicting exacerbations, as it incorporates a history of exacerbations in stratification. The presence of symptoms (as determined by an mMRC grade ≥ 2) was a marker of mortality risk that distinguished group A from group B, and group C from group D. Surprisingly, the rate of death was higher in group B (more symptoms, low risk) than in group C (fewer symptoms, high risk).

Notably, most patients in group C qualified for this group because of the severity of airflow obstruction, not because of a history of exacerbations. Therefore, patients whose symptoms are out of proportion to the severity of obstruction may be at higher risk of death, possibly because of comorbidities such as cardiovascular disease.¹⁵ Patients who qualified for groups C and D by having both a history of frequent exacerbations (≥ 2 per year) and symptoms rather than either one alone had a higher risk of death in 3 years.

Similarly, the symptom-assessment tool that is used—ie, the mMRC grade or the CAT score—also makes a difference.

The Health-Related Quality of Life in COPD in Europe Study¹⁶ retrospectively analyzed data from 1,817 patients to determine whether the cutoff points for symptoms as assessed by mMRC grade and CAT score were equivalent. Although the mMRC grade correlated well with overall health status, the cutoff mMRC grade of 2 or higher did not correspond to a CAT score of 10 or higher, classifying patients with health status impairment as asymptomatic (mean weighted kappa 0.626). The two tools agreed much better when the cutoff was set at an mMRC grade of 1 or higher (mean weighted kappa 0.792).¹⁶

Although assessment schemes continue to evolve as data accumulate, we believe the new system is a welcome initiative that reflects the changing notions of COPD.

Comorbidities matter

Another shift is the recognition that certain comorbidities increase the risk of death. In 1,664 patients with COPD who were followed for 51 months, 12 distinct comorbidities were associated with a higher risk of death after multivariate analysis.¹⁷

The COTE index (COPD-Specific Comorbidity Test) is based on these findings. It awards points as follows:

• 6 points for cancer of the lung, esophagus, pancreas, or breast, or for anxiety
• 2 points for all other cancers, liver cirrhosis, atrial fibrillation or flutter, diabetes with neuropathy, or pulmonary fibrosis
• 1 point for congestive heart failure, gastric or duodenal ulcer, or coronary artery disease.

A COTE index score of 4 or higher was associated with a risk of death 2.2 times higher in each quartile of the BODE index.

We strongly recommend being aware of comorbidities in COPD patients, particularly when symptoms are out of proportion to the severity of obstruction.

SHOULD I USE ANTIBIOTICS TO TREAT ALL COPD EXACERBATIONS?

Infections are thought to cause more than 80% of acute exacerbations of COPD.

Anthonisen et al,¹⁸ in a landmark trial, found broad-spectrum antibiotics to be most helpful if the patient had at least two of the three cardinal symptoms of COPD exacerbation (ie, shortness of breath, increase in sputum volume, and sputum purulence). Antibiotics decreased the rate of treatment failure and led to a more rapid clinical resolution of exacerbation. However, they did not help patients who had milder exacerbations.

Antibiotics may nevertheless have a role in ambulatory patients with mild to moderate COPD who present with exacerbations characterized by one or more cardinal symptoms.

Llor et al,¹⁹ in a multicenter randomized double-blind placebo-controlled trial in Spain, concluded that amoxicillin clavulanate (Augmentin) led to higher clinical cure rates and longer time to the next exacerbation in these patients. Most of the benefit was in patients with more symptoms, consistent with the results of the study by Anthonisen et al.¹⁸

There is also strong evidence to support the use of antibiotics in addition to systemic corticosteroids in hospitalized patients with acute exacerbations of COPD. A 7-day course of doxycycline (Vibramycin) added to a standard regimen of corticosteroids was associated with higher rates of clinical and microbiological cure on day 10 of the exacerbation.²⁰ In a large retrospective cohort study in 84,621 hospitalized patients with COPD exacerbations, fewer of those who received antibiotics needed mechanical ventilation, died, or were readmitted.²¹ Although sicker patients received antibiotics more frequently, their mortality rate was lower than in those who did not receive antibiotics, who were presumably less sick.

A meta-analysis confirmed the salutary effect of antibiotics in inpatients and particularly those admitted to the intensive care unit.²² Mortality rates and hospital length of stay were not affected in patients who were not in intensive care.

Biomarkers such as procalcitonin might help reduce the unnecessary use of antibiotics. Stolz et al²³ conducted a randomized controlled trial in which they based the decision to give antibiotics on a threshold procalcitonin level of at least 1 μg/L in hospitalized patients with COPD exacerbation. The rate of antibiotic use was reduced by more than 40% in the procalcitonin group without any difference in clinical outcomes, 6-month exacerbation rate, or rehospitalization compared with controls. Nonstandardized procalcitonin assays are a possible barrier to the widespread adoption of this threshold.

Comment. In general, we recommend antibiotics for hospitalized patients with COPD exacerbation and look forward to confirmatory data that support the use of biomarkers. For outpatients, we find the Anthonisen criteria useful for decision-making at the point of care.

ARE THERE ANY NEW INTERVENTIONS TO PREVENT COPD EXACERBATIONS?

Macrolides

Macrolides have a proven role in managing chronic suppurative respiratory diseases such as cystic fibrosis²⁴ and diffuse panbronchiolitis.²⁵ Since they are beneficial at lower doses than those used to treat infection, the mechanism may be anti-inflammatory rather than antimicrobial.

Albert et al²⁶ assigned 1,142 patients who had had a COPD exacerbation within a year before enrollment or who were on home oxygen therapy to receive azithromycin (Zithromax) 250 mg daily or placebo.²⁵ The azithromycin group had fewer acute exacerbations (hazard ratio 0.73, 95% CI 0.63–0.84, P < .001), and more patients in the azithromycin group achieved clinically significant improvements in quality of life, ie, a reduction in the St. George’s Respiratory Questionnaire (SGRQ) score of at least 4 points (43% vs 36%, P = .03). Adverse events that were more common in the azithromycin group were hearing loss (25% vs 20%) and macrolide-resistant strains in nasopharyngeal secretions (81% vs 41%). In subgroup analysis, the benefit in terms of reducing exacerbations was greater in patients over age 65, patients on home oxygen, and patients with moderate or severe obstruction compared with those with very severe obstruction.

Comment. Macrolides are a valuable addition to the agents available for preventing COPD exacerbation (Table 2), but their role is still uncertain. Potential topics of research are whether these drugs have a role in patients already on preventive regimens, whether they would have a greater effect in distinct patient populations (eg, patients who have two or more exacerbations per year), and whether their broader use would lead to a change in the resident flora in the community.

Clinicians should exercise caution in the use of azithromycin in light of recent concern about associated cardiac morbidity and death. All patients should undergo electrocardiography to assess the QTc interval before starting treatment, as in the trial by Albert et al.²⁶

Phosphodiesterase inhibitors

Roflumilast (Daliresp) is an oral phosphodiesterase 4 inhibitor approved for treating exacerbations and symptoms of chronic bronchitis in patients with severe COPD (Table 3). Phosphodiesterase 4, one of the 11 isoforms of the enzyme, is found in immune and inflammatory cells and promotes inflammatory responses. Roflumilast has anti-inflammatory properties but no acute bronchodilatory effect.²⁷ Several phase 3 trials found the compound to have beneficial effects.

Calverley et al²⁸ performed two placebo-controlled double-blind trials in outpatients with the clinical diagnosis of COPD who had chronic cough; increased sputum production; at least one recorded exacerbation requiring corticosteroids or hospitalization, or both; and an FEV₁ of 50% or less. Patients were randomized to receive roflumilast 500 μg once a day (n = 1,537) or placebo (n = 1,554) for 1 year. The rate of moderate to severe exacerbations was 1.17 per year with roflumilast vs 1.37 with placebo (P < .0003). Adverse events were significantly more common with roflumilast and were related to the known side effects of the drug, namely, diarrhea, weight loss, decreased appetite, and nausea.

Fabbri et al²⁹ performed two other placebo-controlled double-blind multicenter trials, studying the combinations of roflumilast with salmeterol (Serevent) and roflumilast with tiotropium (Spiriva) compared with placebo in 1,676 patients with COPD who had post-bronchodilator FEV₁ values of 40% to 70% of predicted. The mean prebronchodilator FEV₁ improved by 49 mL (P < .0001) in the salmeterol-plus-roflumilast trial and by 80 mL (P < .0001) in the tiotropium-plus-roflumilast trial compared with placebo. Fewer patients on roflumilast had exacerbations of any severity in both trials (risk ratio 0.82, P = .0419 and risk ratio 0.75, P = .0169, respectively).

No trial has yet addressed whether roflumilast is better than the combination of a long-acting muscarinic antagonist and a beta agonist, or whether roflumilast can be substituted for inhaled corticosteroids in a new triple-therapy combination. Clinicians should also be aware of psychiatric side effects of roflumilast, which include depression and, possibly, suicide.

ARE THERE ANY NEW BRONCHODILATORS FOR PATIENTS WITH COPD?

Long-acting muscarinic antagonists

Reversible airflow obstruction and mucus secretion are determined by the vagal cholinergic tone in patients with COPD.³⁰ Antagonism of cholinergic (muscarinic) receptors results in bronchodilation and reduction in mucus production. Consequently, inhaled anticholinergic agents are the first-line therapy for COPD (Table 4).

Tiotropium bromide is a long-acting antimuscarinic approved in 2002 by the US Food and Drug Administration (FDA). The UPLIFT trial (Understanding Potential Long-Term Impacts on Function With Tiotropium)³¹ enrolled 5,993 patients with a mean FEV₁ of 48% of predicted. Over a 4-year follow-up, significant improvements in mean FEV₁ values (ranging from 87 mL to 103 mL before bronchodilation and 47 mL to 65 mL after bronchodilation, P < .001) in the tiotropium group were observed compared with placebo. The rate of the primary end point—the rate of decline in mean FEV₁—was not different between tiotropium and placebo. However, there were important salutary effects in multiple clinical end points in the tiotropium group. Health-related quality of life as measured by the SGRQ improved in a clinically significant manner (> 4 points) in favor of tiotropium in a higher proportion of patients (45% vs 36%, P < .001). Tiotropium reduced the number of exacerbations per patient year (0.73 ± 0.02 vs 0.85 ± 0.02, RR = 0.86 (95% CI 0.81–0.91), P < .001) and the risk of respiratory failure (RR = 0.67, 95% CI 0.51–0.89). There were no significant differences in the risk of myocardial infarction, stroke, or pneumonia.

Aclidinium bromide (Tudorza Pressair) is a long-acting antimuscarinic recently approved by the FDA. Compared with tiotropium, it has a slightly faster onset of action and a considerably shorter half-life (29 hours vs 64 hours).^32,33 Its dosage is 400 μg twice daily by inhalation. It provides sustained bronchodilation over 24 hours and may have a favorable side-effect profile, because it undergoes rapid hydrolysis in human plasma.³⁴

ACCORD COPD I³⁵ and ATTAIN,³⁶ two phase 3 trials in patients with moderate-to severe COPD, found that twice-daily aclidinium was associated with statistically and clinically significant (> 100 mL) improvements in trough and peak FEV₁ compared with placebo. Health status (assessed by SGRQ) and dyspnea (assessed by transitional dyspnea index) also improved significantly. However, improvements beyond minimum clinically significant thresholds were achieved only with 400 μg twice-daily dosing.

To date, no study has evaluated the impact of aclidinium on COPD exacerbation as a primary end point. Fewer moderate to severe exacerbations were reported in an earlier 52-week study of once-daily aclidinium (ACCLAIM COPD II) but not in ACCLAIM COPD I.³⁷

Aclidinium may offer an advantage over tiotropium in patients who have nocturnal symptoms. Twice-daily aclidinium 400 μg was associated with superior FEV₁ area-under-the-curve values compared with placebo and tiotropium, the difference mostly owing to improved nocturnal profile.³⁸

Long-acting beta-2 agonists

Stimulation of airway beta-2 receptors relaxes smooth muscles and consequently dilates bronchioles via a cyclic adenosine monophosphate-dependent pathway.³⁹

Short-acting beta-2 agonists such as albuterol and terbutaline have long been used as rescue medications for obstructive lung disease. Long-acting beta-2 agonists provide sustained bronchodilation and are therefore more efficacious as maintenance medications. Salmeterol, formoterol (Foradil), and arformoterol (Brovana) are long-acting beta-2 agonists in clinical use that are taken twice daily.

Clinical studies indicate that use of long-acting beta-2 agonists leads to significant improvements in FEV₁,^40–42 dynamic hyperinflation, exercise tolerance,^43,44 and dyspnea.^45,46 These drugs have also been associated with significant improvements in health-related quality of life and in the frequency of exacerbations.^47–49

In patients with asthma, long-acting beta agonists may increase the risk of death.⁵⁰ In contrast, in patients with COPD, they appear to offer a survival advantage when used in combination with inhaled corticosteroids,⁵¹ and some argue that this benefit is entirely from the long-acting beta agonist (a 17% reduction in mortality) rather than the inhaled corticosteroid (0% reduction in mortality).⁵²

Indacaterol (Arcapta), approved in July 2011, is the first once-daily beta agonist or “ultra-long-acting” beta agonist (Table 5). Possibly because it has a high affinity for the lipid raft domain of the cell membrane where beta-2 receptors are coupled to second messengers,⁵³ the drug has a 24-hour duration of action.

In patients with COPD, inhaled indacaterol 150 μg once daily improved airflow obstruction and health status as measured by SGRQ compared with salmeterol 50 μg twice daily and placebo.⁵⁴ At the higher dose of 300 μg daily, the 52-week INVOLVE trial⁵⁵ demonstrated early and more sustained improvement in FEV₁ compared with placebo and formoterol. In this study, a lower exacerbation rate than with placebo was also noted. The drug has also shown equivalent bronchodilator efficacy at 150 μg and 300 μg daily dosing compared with tiotropium.⁵⁶

The benefits of a longer-acting bronchodilator such as indacaterol are likely mediated by smoothing out airway bronchomotor tone over 24 hours without the dips seen with shorter-acting agents and by improvement of the FEV₁ trough before the subsequent dose is due, aptly named “pharmacologic stenting.”⁵⁷ Once-daily dosing should also foster better adherence. The safety profile appears excellent with no increase in cardiovascular or cerebrovascular events compared with placebo.⁵⁸

The FDA approved the 75-μg daily dose instead of the higher doses used in the studies mentioned above. This decision was based on the observation that there appeared to be a flattened dose-response in patients with more severe COPD, with no further improvement in trough FEV₁ at higher doses.⁵⁹

DOES VITAMIN D SUPPLEMENTATION HAVE A ROLE IN COPD MANAGEMENT?

Vitamin D is vital for calcium and phosphate metabolism and bone health. Low vitamin D levels are associated with diminished leg strength and falls in the elderly.⁶⁰ Osteoporosis, preventable with vitamin D and calcium supplementation, is linked to thoracic vertebral fracture and consequent reduced lung function.^61,62

Patients with COPD are at higher risk of vitamin D deficiency, and more so if they also are obese, have advanced airflow obstruction, are depressed, or smoke.⁶² Therefore, there are sound reasons to look for vitamin D deficiency in patients with COPD and to treat it if the 25-hydroxyvitamin D level is less than 10 ng/ mL (Table 6).

Vitamin D may also have antimicrobial and immunomodulatory effects.⁶³ Since COPD exacerbations are frequently caused by infection, it was hypothesized that vitamin D supplementation might reduce the rate of exacerbations.

In a study in 182 patients with moderate to very severe COPD and a history of recent exacerbations, high-dose vitamin D supplementation (100,000 IU) was given every 4 weeks for 1 year.⁶⁴ There were no differences in the time to first exacerbation, in the rate of exacerbation, hospitalization, or death, or in quality of life between the placebo and intervention groups. However, subgroup analysis indicated that, in those with severe vitamin D deficiency at baseline, the exacerbation rate was reduced by more than 40%.

Comment. We recommend screening for vitamin D deficiency in patients with COPD. Supplementation is appropriate in those with low levels, but data indicate no role in those with normal levels.

WHAT ARE THE NONPHARMACOLOGIC APPROACHES TO COPD TREATMENT?

Noninvasive positive-pressure ventilation

Nocturnal noninvasive positive-pressure ventilation may be beneficial in patients with severe COPD, daytime hypercapnia, and nocturnal hypoventilation, particularly if higher inspiratory pressures are selected (Table 7).^65,66

For instance, a randomized controlled trial of noninvasive positive-pressure ventilation plus long-term oxygen therapy compared with long-term oxygen therapy alone in hypercapnic COPD demonstrated a survival benefit in favor of ventilation (hazard ratio 0.6).⁶⁷

In another randomized trial,⁶⁸ settings that aimed to maximally reduce Paco₂ (mean inspiratory positive airway pressure 29 cm H₂O with a backup rate of 17.5/min) were compared with low-intensity positive airway pressure (mean inspiratory positive airway pressure 14 cm H₂O, backup rate 8/min). The high inspiratory pressures increased the daily use of ventilation by 3.6 hours per day and improved exercise-related dyspnea, daytime Paco₂, FEV₁, vital capacity, and health-related quality of life⁶⁶ without disrupting sleep quality.⁶⁸

Caveats are that acclimation to the high pressures was achieved in the hospital, and the high pressures were associated with a significant increase in air leaks.⁶⁶

Comments. Whether high-pressure noninvasive positive-pressure ventilation can be routinely implemented and adopted in the outpatient setting, and whether it is associated with a survival advantage remains to be determined. The advantages of noninvasive positive-pressure ventilation in the setting of hypercapnic COPD appear to augment those of pulmonary rehabilitation, with improved quality of life, gas exchange, and exercise tolerance, and a slower decline of lung function.⁶⁹

Pulmonary rehabilitation

Pulmonary rehabilitation is a multidisciplinary approach to managing COPD (Table 8).

Patients participate in three to five supervised sessions per week, each lasting 3 to 4 hours, for 6 to 12 weeks. Less-frequent sessions may not be effective. For instance, in a randomized trial, exercising twice a week was not enough.⁷⁰ Additionally, a program lasting longer than 12 weeks produced more sustained benefits than shorter programs.⁷¹

A key component is an exercise protocol centered on the lower extremities (walking, cycling, treadmill), with progressive exercise intensity to a target of about 60% to 80% of the maximal exercise tolerance,⁷² though more modest targets of about 50% can also be beneficial.⁷³

Exercise should be tailored to the desired outcome. For instance, training of the upper arms may help with activities of daily living. In one study, unsupported (against gravity) arm training improved upper-extremity function more than supported arm training (by ergometer).⁷⁴ Ventilatory muscle training is less common, as most randomized trials have not shown conclusive evidence of benefit. Current guidelines do not recommend routine inspiratory muscle training.⁷¹

Even though indices of pulmonary function do not improve after an exercise program, randomized trials have shown that pulmonary rehabilitation improves exercise capacity, dyspnea, and health-related quality of life; improves cost-effectiveness of health care utilization; and provides psychosocial benefits that often exceed those of other therapies. Although there is no significant evidence of whether pulmonary rehabilitation improves survival in patients with COPD,⁷¹ an observational study documented improvements in BODE scores as well as a reduction in respiratory mortality rates in patients undergoing pulmonary rehabilitation.⁷⁵

A limitation of pulmonary rehabilitation is that endurance and psychological and cognitive function decline significantly if exercise is not maintained. However, the role of a maintenance program is uncertain, with long-term benefits considered modest.⁷¹

Lung-volume reduction surgery

Lung-volume reduction consists of surgical wedge resections of emphysematous areas of the lung (Table 9).

The National Emphysema Treatment Trial⁷⁶ randomized 1,218 patients to undergo either lung-volume reduction surgery or maximal medical therapy. Surgery improved survival, quality of life, and dyspnea in patients with upper-lobe emphysema and a low exercise capacity (corresponding to < 40 watts for men or < 25 watts for women in the maximal power achieved on cycle ergometry). While conferring no survival benefit in patients with upper-lobe-predominant emphysema and high exercise capacity, this surgery is likely to improve exercise capacity and quality of life in this subset of patients.

Importantly, the procedure is associated with a lower survival rate in patients with an FEV₁ lower than 20%, homogeneous emphysema, a diffusing capacity of the lung for carbon monoxide lower than 20%, non-upper-lobe emphysema, or high baseline exercise capacity.

The proposed mechanisms of improvement of lung function include placing the diaphragm in a position with better mechanical advantage, reducing overall lung volume, better size-matching between the lungs and chest cavity, and restoring elastic recoil.^76,77

Ongoing trials aim to replicate the success of lung-volume reduction using nonsurgical bronchoscopic techniques with one-way valves, coils, biologic sealants, thermal ablation, and airway stents.

Noninvasive positive pressure ventilation (NIPPV) is any form of positive ventilatory support applied without an endotracheal tube, including continuous positive airway pressure (CPAP).¹ The role of NIPPV in acute care has been discussed in an earlier review in the Cleveland Clinic Journal of Medicine.²

NIPPV is also used at night in outpatients with stable chronic conditions, first used in the 1980s in the treatment of obstructive sleep apnea³ and neuromuscular diseases,⁴ and since then in several other conditions including sleep disorders associated with congestive heart failure (including sleep apnea and the Cheyne-Stokes respiration-central sleep apnea syndrome), chronic obstructive pulmonary disease (COPD), and the obesity-hypoventilation syndrome.

In this review, we discuss the different types of NIPPV, the specific conditions in which they can be used, and the indications, recommendations, and evidence supporting the efficacy of NIPPV in outpatients.

THE TYPES OF NIPPV AND THEIR USES

Although the conditions for which different types of NIPPV can be used overlap significantly, each type has general indications and different goals of treatment. This section begins with types of NIPPV that are predominantly used to treat sleep-disordered breathing, and then proceeds to those predominantly used for conditions associated with hypoventilation and hypercapnia.

Continuous positive airway pressure

CPAP, currently the most widely used form of NIPPV, applies a constant level of positive pressure at the airway opening during spontaneous breathing.

CPAP is commonly used to treat obstructive sleep-disordered breathing, with the goals of improving daytime sleepiness and reducing cardiovascular risk. It has also been used to treat sleep-disordered breathing associated with congestive heart failure.

CPAP’s role in the support of ventilation is limited and indirect. For instance, it has been used in the obesity-hypoventilation syndrome and in the “overlap” syndrome (in which both sleep apnea and COPD coexist). However, its benefits in those conditions are probably derived in large part from correction of underlying obstructive sleep apnea.

The mechanisms of action of CPAP include:

• Preventing intermittent narrowing and collapse of the airway in patients with obstructive sleep apnea-hypopnea syndrome by acting as a pneumatic splint during sleep^3,5,6
• Counteracting auto-positive end-expiratory pressure, thereby reducing respiratory muscle load, reducing the work of breathing, and lowering daytime Paco₂ in patients with coexistent COPD and obstructive sleep apnea-hypopnea syndrome (the overlap syndrome)^7–9
• Improving lung function (particularly the functional residual capacity) and daytime gas exchange in obstructive sleep apnea-hypopnea syndrome ¹⁰
• Improving left ventricular systolic function in patients with heart failure coexisting with obstructive sleep apnea-hypopnea syndrome.^11,12

Auto-CPAP is delivered via a self-titrating CPAP device, which uses algorithms to detect variations in the degree of obstruction and consequently adjusts the pressure level to restore normal breathing. Auto-CPAP therefore compensates for factors that modify the upper airway collapsibility, such as body posture during sleep, stage of sleep, use of alcohol, and drugs that affect upper airway muscle tone.¹³

Although one of the premises of using auto-CPAP is that it improves the patient’s satisfaction and compliance, several studies found it to be no more effective than fixed CPAP for treating obstructive sleep apnea-hypopnea syndrome.^14–16 Current guidelines of the American Academy of Sleep Medicine do not recommend self-titrating CPAP devices to diagnose obstructive sleep apnea or to treat patients with cardiopulmonary disorders or other conditions in which nocturnal desaturation may be unrelated to obstructive events.¹⁷

Adaptive servo-ventilation

Adaptive servo-ventilation was developed for Cheyne-Stokes respiration-central sleep apnea syndrome in patients with congestive heart failure, who may have periods of crescendo-decrescendo change in tidal volume (Cheyne-Stokes respiration) with possible intercalated episodes of central apnea or hypopnea. It is also applied in patients with the complex sleep apnea syndrome.

Adaptive servo-ventilation devices are usually set at an expiratory positive airway pressure (EPAP) level sufficient to control obstructive sleep apnea. The device then automatically adjusts the pressure support for each inspiration, within a prespecified range, to maintain a moving-target ventilation set at 90% of the patient’s recent average ventilation. The aim is to stabilize breathing and reduce respiratory alkalosis, which can trigger apnea reentry cycles.¹⁸

Bilevel positive airway pressure

Bilevel positive airway pressure (bilevel PAP) can be of use in sleep-disordered breathing (including cases associated with congestive heart failure), but it is predominantly applied in conditions associated with hypoventilation.

Bilevel PAP devices deliver a higher pressure during inspiration (inspiratory positive airway pressure, or IPAP) and a lower pressure during expiration (EPAP). The gradient between IPAP and EPAP is of key importance in maintaining alveolar ventilation and reducing Paco₂. The IPAP acts as pressure support to augment the patient’s effort, maintain adequate alveolar ventilation, unload respiratory muscles, decrease the work of breathing, and control obstructive hypopnea, whereas EPAP is set to maintain upper airway patency, control obstructive apnea, improve functional residual capacity, and prevent microatelectasis.

Although there is no evidence that bilevel PAP is better adhered to or more effective than CPAP, current guidelines propose it as an option for patients who require high pressures to control obstructive sleep apnea-hypopnea syndrome or for those who cannot tolerate exhaling against a high fixed CPAP pressure.¹⁹

Other, more-common uses of bilevel PAP are to treat coexisting central sleep apnea or hypoventilation,¹⁹ the obesity-hypoventilation syndrome with residual alveolar hypoventilation despite CPAP and control of concomitant obstructive sleep apnea-hypopnea syndrome,^5,20 severe stable COPD with significant nocturnal hypoventilation and daytime hypercarbia,²¹ and restrictive pulmonary diseases.²¹

Average volume-assured pressure support

CONDITIONS IN WHICH NOCTURNAL NIPPV IS USED IN OUT PATIENTS

Obstructive sleep apnea-hypopnea syndrome

Obstructive sleep apnea-hypopnea syndrome is estimated to affect 2% of women and 4% of men.²⁵ It is characterized by recurrent episodes of partial (hypopnea) or complete (apnea) upper airway obstruction during sleep despite ongoing inspiratory efforts, with associated episodes of arousal or desaturation or both. Corresponding symptoms include excessive daytime sleepiness, choking and gasping during sleep, recurrent awakenings from sleep, unrefreshing sleep, daytime fatigue, and impaired concentration that is not explained by other factors.²⁶

Current understanding of the pathophysiology of obstructive sleep apnea implicates an impairment in the balance between factors that promote collapsibility of the airway (including obesity and anatomic issues such as the volume of the soft-tissue structures surrounding the upper airway) and the compensatory neuromuscular response.^27,28

Long-standing obstructive sleep apnea-hypopnea syndrome has been linked in prospective studies to the development of hypertension,^29–31 coronary artery disease,^32,33 increased coagulation,^34,35 and stroke or death from any cause.^36,37 It is also associated with a greater rate and severity of motor vehicular accidents,³⁸ greater health care utilization, impaired work performance, and occupational injuries.³⁹

Strong evidence exists that NIPPV (most commonly CPAP) is beneficial in obstructive sleep apnea-hypopnea syndrome, improving sleep quality, sleepiness, cognitive impairment, and quality of life,^40,41 decreasing motor vehicle accidents,⁴² lowering blood pressure, ^43,44 and decreasing the rates of myocardial infarction,³² stroke,³² and death.⁴⁵

The American Academy of Sleep Medicine recommends CPAP as an optional adjunctive therapy to lower blood pressure in patients with obstructive sleep apnea-hypopnea syndrome with concomitant hypertension.¹⁹ This is supported by a recent study that suggested that CPAP may have additional benefits on blood pressure in a subgroup of patients with uncontrolled hypertension while on antihypertensive medications.⁴⁶ Indications with Medicare guidelines for reimbursement of CPAP devices are summarized in Table 2.

Complex sleep apnea syndrome

The complex sleep apnea syndrome is characterized by the emergence of significant central sleep apnea or Cheyne-Stokes respiration after obstructive events have been brought under control with NIPPV in patients who initially appear to have obstructive sleep apnea-hypopnea syndrome. A retrospective study of patients with the complex sleep apnea syndrome who continued their NIPPV use until a subsequent polysomnographic study and NIPPV titration showed that the syndrome may resolve spontaneously, but that 46% of patients had a persistently elevated apnea-hypopnea index with central apnea activity.⁴⁷

Restoration of upper airway patency by CPAP and dysregulation or delayed adaptation of chemosensitive ventilatory control to a changing Paco₂ level may be a key pathophysiologic mechanism of the complex sleep apnea syndrome.⁴⁸ In this mechanism, increased ventilation from restored airway patency and from an increase in the slope of the ventilatory response may intermittently draw the Paco₂ to below the hypocapnic apneic threshold and trigger episodes of central apnea.⁴⁸

The ideal NIPPV device for use in the complex sleep apnea syndrome should be able to provide enough pressure to resolve the obstructive sleep apnea-hypopnea syndrome while maintaining proper ventilatory support during central apnea episodes without fluctuations of Paco₂, which could further worsen the dysregulated ventilatory control. Currently, adaptive servo-ventilation appears to be superior to bilevel PAP and CPAP in the management of the complex sleep apnea syndrome.^49,50

Sleep disturbances associated with cardiac dysfunction

There are specific indications for NIPPV modes in the setting of respiratory sleep disturbances associated with heart failure.

Obstructive sleep apnea in congestive heart failure. The prevalence of obstructive sleep apnea in patients with impaired left ventricular ejection fraction is 11% to 53%.⁵¹ Obstructive sleep apnea-hypopnea syndrome can worsen congestive heart failure by causing a periodic increase in negative intrathoracic pressure from breathing against an occluded airway, by raising arterial blood pressure, and causing tachycardia from sympathetic nervous system stimulation from hypoxia, hypercarbia, and arousals.^52,53 Both heart failure and sleep apnea contribute in an additive manner to the increased sympathetic nervous activity.⁵⁴

Fortunately, treatment with CPAP has been found to reduce systolic blood pressure and improve left ventricular systolic function in medically treated patients with heart failure and coexisting obstructive sleep apnea.^11,12 Furthermore, in a randomized trial in patients with stable congestive heart failure and newly diagnosed obstructive sleep apnea-hypopnea syndrome, a greater improvement in cardiac function was observed in patients on bilevel PAP than in those on CPAP.⁵⁵ The authors speculated that bilevel PAP might provide more unloading of the respiratory muscles, reduce the work of breathing more, and result in less positive intrathoracic pressure than with CPAP, and that the higher intrathoracic pressure with CPAP could reduce the left ventricular ejection fraction in patients with low filling pressures (pulmonary capillary wedge pressure < 12 mm Hg) and low baseline left ventricular ejection fractions (< 30%).⁵⁵

Whether these interventions reduce the mortality rate is uncertain. In a prospective nonrandomized study, 9 (24%) of 37 patients who had heart failure with untreated obstructive sleep apnea died, compared with no deaths in 14 treated patients (P = .07).⁵⁶

Cheyne-Stokes respiration with central sleep apnea in congestive heart failure. A related but different situation is central apnea associated with congestive heart failure.

There are several pathophysiologic mechanisms of Cheyne-Stokes respiration with central sleep apnea. Specifically, the elevation of left ventricular filling pressures, end-diastolic volumes, and pulmonary congestion generate hyperventilation, chronic hypocapnia, and increased chemoreceptor responsiveness, which contribute to the development of central apnea by promoting a decrease in the Paco₂ during sleep to below the hypocapnic apneic threshold.^57,58 Additionally, an increase in circulation time may result in periodicity of breathing and hyperpnea.⁵⁹ Obstructive events can then occur at the end of the central events corresponding with the nadir of the inspiratory drive.^60,61

The Canadian Continuous Positive Airway Pressure for Patients With Central Sleep Apnea and Heart Failure (CANPAP) trial, a randomized trial of CPAP in this clinical setting, showed that compared with optimal medical therapy alone, CPAP plus optimal medical therapy improved the ejection fraction, reduced central sleep apnea, improved nocturnal oxygenation, and improved the 6-minute walking distance, but without a survival benefit.⁶² The disappointing survival results from CANPAP have to be interpreted in the context that CPAP may have failed to control the central apnea in some patients, such that the mean apnea-hypopnea index in treated patients (19 events/hour) remained above the entry criterion for recruitment (15 events/hour). In a post hoc analysis of this study, the heart-transplantation-free survival rate was significantly greater in the subgroup of patients in whom CPAP effectively suppressed central sleep apnea (< 15 events/hour).⁶³

Other NIPPV modes such as bilevel PAP with backup rate and adaptive servo-ventilation have been shown in some studies to be superior to CPAP in controlling respiratory events, with adaptive servo-ventilation being the most effective in controlling central, mixed, and complex sleep apnea in this setting. ^49,50 Whether more effective resolution of obstructive and central events with these treatment modes translates into improved mortality rates and transplantation-free survival rates remains to be determined.

Obesity-hypoventilation syndrome refers to daytime hypercapnia (Paco₂ > 45 mm Hg) in obese people when no other cause of hypoventilation is present.

The prevalence of obesity-hypoventilation syndrome among patients with obstructive sleep apnea-hypopnea syndrome is 20% to 30% and is greater in extremely obese patients (body mass index > 40 kg/m²).⁶⁴ However, about 10% of patients with obesity-hypoventilation syndrome do not have obstructive sleep apnea-hypopnea syndrome.⁶⁴ Additionally, nocturnal hypoxemia and diurnal hypercapnia persist in about 40% of patients with obesity-hypoventilation syndrome after CPAP eliminates their sleep apnea.⁶⁵ Therefore, factors other than sleep apnea contribute to the development of obesity-hypoventilation syndrome, and in a meta-analysis, factors associated with daytime hypercapnia included, in addition to body mass index and the apnea-hypopnea index, mean overnight oxygen saturation and severity of restrictive pulmonary function.⁶⁶ Predictors of success with CPAP include better spirometric findings, a higher apnea-hypopnea index, and adequate oxygenation.^67,68

Bilevel PAP therapy can be tried in patients in whom CPAP by itself fails. In a study of patients with obesity-hypoventilation syndrome in whom initial CPAP treatment failed, average volume-assured pressure support lowered Paco₂ compared to bilevel PAP alone, but did not further improve oxygenation, sleep quality, or quality of life.⁶⁹

Restrictive pulmonary diseases

Neuromuscular diseases and thoracic cage abnormalities. Noninvasive ventilation has been used in patients with progressive neuromuscular disorders or severe thoracic cage abnormalities, with recognized benefits including an improved survival rate and improved quality of life.^70,71 However, NIPPV is used in only 9% of patients with amyotrophic lateral sclerosis when clearly indicated.⁷² The indications and Medicare guidelines for reimbursement of NIPPV (with or without a backup rate) in this setting are shown in Table 2.

Potential contraindications to starting NIPPV in this population include upper airway obstruction, failure to clear secretions despite optimal noninvasive support, inability to achieve a mask fit, and intolerance of the intervention.^73,74

The mechanisms of benefit of NIPPV in these settings include improvements in daytime blood gas levels (including hypercapnia⁷⁵), a reduction in the oxygen cost of breathing,⁷⁶ an increase in the ventilatory response to carbon dioxide,⁷⁵ and improved lung compliance.⁷⁷

Chronic hypercapnic failure due to severe COPD

The use of NIPPV in chronic COPD is less well established than in patients with exacerbations of COPD,⁷⁸ and limitations in its use are reflected in the more stringent Medicare indications for NIPPV in this setting (Table 2).

A particular subset of patients with stable COPD who may benefit from NIPPV includes those with daytime hypercapnia and super-imposed nocturnal hypoventilation.⁷⁸ The potential benefits of NIPPV in these patients include improved daytime and nocturnal gas exchange, increased sleep duration, and improved quality of life.⁷⁸ Additionally, a recent randomized controlled trial of NIPPV plus long-term oxygen therapy compared with oxygen therapy alone in patients with severe COPD and a Paco₂ greater than 46 mm Hg demonstrated a survival benefit in favor of adding NIPPV (hazard ratio 0.6).⁷⁹

However, that study also found no reduction in hospitalization rates, an apparent worsening in general and mental health (as reflected on the 36-Item Short Form Health Survey or SF-36, a quality-of-life questionnaire), as well as increased confusion and bewilderment (reflected on the Profile of Mood States scale).⁷⁹ These potentially deleterious effects may explain why adherence to NIPPV is low in patients with stable COPD: only 37% to 57% of patients continued to use it in several reported studies.^79–81

A level of inspiratory pressure support that is insufficient to reduce hypercapnia may account for the low adherence rate and worsened quality of life in such patients. For instance, in a randomized trial,⁸² compared with low-intensity NIPPV (mean IPAP 14 cm H₂O, backup rate 8 per minute), settings that aimed to maximally reduce Paco₂ (mean IPAP 29 cm H₂O with a backup rate of 17.5 per minute) increased the daily use of NIPPV by 3.6 hours/day and improved exercise-related dyspnea, daytime Paco₂, forced expiratory volume in 1 second (FEV₁), vital capacity, and health-related quality of life.

The overlap syndrome was first described by Flenley in 1985 as a combination of chronic respiratory disease (more generally limited to COPD) and obstructive sleep apnea-hypopnea syndrome.⁸³ Epidemiologic studies do not consistently show a higher incidence of obstructive sleep apnea-hypopnea syndrome in patients with COPD, but the exaggerated oxygen desaturation during sleep in patients with this combination increases the risk of hypoxemia, hypercapnia, and pulmonary hypertension. ⁸⁴ In addition, there was evidence of higher risks of death and of hospitalization for COPD in patients with the overlap syndrome. ⁸⁵ NIPPV is the main treatment for obstructive sleep apnea-hypopnea syndrome with or without COPD.

A recent study by Marin et al⁸⁵ showed that CPAP was associated with improved survival and decreased hospitalization in patients with the overlap syndrome. However, polysomnography or nocturnal oximetry while on NIPPV alone must be done, as additional nocturnal oxygen therapy may be warranted when significant chronic respiratory illness coexists with sleep apnea.
 

Acknowledgment: The authors gratefully acknowledge the contribution of Scott Marlow, RRT, to Table 2 of this review.

Noninvasive positive pressure ventilation (NIPPV) is any form of positive ventilatory support applied without an endotracheal tube, including continuous positive airway pressure (CPAP).¹ The role of NIPPV in acute care has been discussed in an earlier review in the Cleveland Clinic Journal of Medicine.²

NIPPV is also used at night in outpatients with stable chronic conditions, first used in the 1980s in the treatment of obstructive sleep apnea³ and neuromuscular diseases,⁴ and since then in several other conditions including sleep disorders associated with congestive heart failure (including sleep apnea and the Cheyne-Stokes respiration-central sleep apnea syndrome), chronic obstructive pulmonary disease (COPD), and the obesity-hypoventilation syndrome.

In this review, we discuss the different types of NIPPV, the specific conditions in which they can be used, and the indications, recommendations, and evidence supporting the efficacy of NIPPV in outpatients.

THE TYPES OF NIPPV AND THEIR USES

Although the conditions for which different types of NIPPV can be used overlap significantly, each type has general indications and different goals of treatment. This section begins with types of NIPPV that are predominantly used to treat sleep-disordered breathing, and then proceeds to those predominantly used for conditions associated with hypoventilation and hypercapnia.

Continuous positive airway pressure

CPAP, currently the most widely used form of NIPPV, applies a constant level of positive pressure at the airway opening during spontaneous breathing.

CPAP is commonly used to treat obstructive sleep-disordered breathing, with the goals of improving daytime sleepiness and reducing cardiovascular risk. It has also been used to treat sleep-disordered breathing associated with congestive heart failure.

CPAP’s role in the support of ventilation is limited and indirect. For instance, it has been used in the obesity-hypoventilation syndrome and in the “overlap” syndrome (in which both sleep apnea and COPD coexist). However, its benefits in those conditions are probably derived in large part from correction of underlying obstructive sleep apnea.

The mechanisms of action of CPAP include:

• Preventing intermittent narrowing and collapse of the airway in patients with obstructive sleep apnea-hypopnea syndrome by acting as a pneumatic splint during sleep^3,5,6
• Counteracting auto-positive end-expiratory pressure, thereby reducing respiratory muscle load, reducing the work of breathing, and lowering daytime Paco₂ in patients with coexistent COPD and obstructive sleep apnea-hypopnea syndrome (the overlap syndrome)^7–9
• Improving lung function (particularly the functional residual capacity) and daytime gas exchange in obstructive sleep apnea-hypopnea syndrome ¹⁰
• Improving left ventricular systolic function in patients with heart failure coexisting with obstructive sleep apnea-hypopnea syndrome.^11,12

Auto-CPAP is delivered via a self-titrating CPAP device, which uses algorithms to detect variations in the degree of obstruction and consequently adjusts the pressure level to restore normal breathing. Auto-CPAP therefore compensates for factors that modify the upper airway collapsibility, such as body posture during sleep, stage of sleep, use of alcohol, and drugs that affect upper airway muscle tone.¹³

Although one of the premises of using auto-CPAP is that it improves the patient’s satisfaction and compliance, several studies found it to be no more effective than fixed CPAP for treating obstructive sleep apnea-hypopnea syndrome.^14–16 Current guidelines of the American Academy of Sleep Medicine do not recommend self-titrating CPAP devices to diagnose obstructive sleep apnea or to treat patients with cardiopulmonary disorders or other conditions in which nocturnal desaturation may be unrelated to obstructive events.¹⁷

Adaptive servo-ventilation

Adaptive servo-ventilation was developed for Cheyne-Stokes respiration-central sleep apnea syndrome in patients with congestive heart failure, who may have periods of crescendo-decrescendo change in tidal volume (Cheyne-Stokes respiration) with possible intercalated episodes of central apnea or hypopnea. It is also applied in patients with the complex sleep apnea syndrome.

Adaptive servo-ventilation devices are usually set at an expiratory positive airway pressure (EPAP) level sufficient to control obstructive sleep apnea. The device then automatically adjusts the pressure support for each inspiration, within a prespecified range, to maintain a moving-target ventilation set at 90% of the patient’s recent average ventilation. The aim is to stabilize breathing and reduce respiratory alkalosis, which can trigger apnea reentry cycles.¹⁸

Bilevel positive airway pressure

Bilevel positive airway pressure (bilevel PAP) can be of use in sleep-disordered breathing (including cases associated with congestive heart failure), but it is predominantly applied in conditions associated with hypoventilation.

Bilevel PAP devices deliver a higher pressure during inspiration (inspiratory positive airway pressure, or IPAP) and a lower pressure during expiration (EPAP). The gradient between IPAP and EPAP is of key importance in maintaining alveolar ventilation and reducing Paco₂. The IPAP acts as pressure support to augment the patient’s effort, maintain adequate alveolar ventilation, unload respiratory muscles, decrease the work of breathing, and control obstructive hypopnea, whereas EPAP is set to maintain upper airway patency, control obstructive apnea, improve functional residual capacity, and prevent microatelectasis.

Although there is no evidence that bilevel PAP is better adhered to or more effective than CPAP, current guidelines propose it as an option for patients who require high pressures to control obstructive sleep apnea-hypopnea syndrome or for those who cannot tolerate exhaling against a high fixed CPAP pressure.¹⁹

Other, more-common uses of bilevel PAP are to treat coexisting central sleep apnea or hypoventilation,¹⁹ the obesity-hypoventilation syndrome with residual alveolar hypoventilation despite CPAP and control of concomitant obstructive sleep apnea-hypopnea syndrome,^5,20 severe stable COPD with significant nocturnal hypoventilation and daytime hypercarbia,²¹ and restrictive pulmonary diseases.²¹

Average volume-assured pressure support

CONDITIONS IN WHICH NOCTURNAL NIPPV IS USED IN OUT PATIENTS

Obstructive sleep apnea-hypopnea syndrome

Obstructive sleep apnea-hypopnea syndrome is estimated to affect 2% of women and 4% of men.²⁵ It is characterized by recurrent episodes of partial (hypopnea) or complete (apnea) upper airway obstruction during sleep despite ongoing inspiratory efforts, with associated episodes of arousal or desaturation or both. Corresponding symptoms include excessive daytime sleepiness, choking and gasping during sleep, recurrent awakenings from sleep, unrefreshing sleep, daytime fatigue, and impaired concentration that is not explained by other factors.²⁶

Current understanding of the pathophysiology of obstructive sleep apnea implicates an impairment in the balance between factors that promote collapsibility of the airway (including obesity and anatomic issues such as the volume of the soft-tissue structures surrounding the upper airway) and the compensatory neuromuscular response.^27,28

Long-standing obstructive sleep apnea-hypopnea syndrome has been linked in prospective studies to the development of hypertension,^29–31 coronary artery disease,^32,33 increased coagulation,^34,35 and stroke or death from any cause.^36,37 It is also associated with a greater rate and severity of motor vehicular accidents,³⁸ greater health care utilization, impaired work performance, and occupational injuries.³⁹

Strong evidence exists that NIPPV (most commonly CPAP) is beneficial in obstructive sleep apnea-hypopnea syndrome, improving sleep quality, sleepiness, cognitive impairment, and quality of life,^40,41 decreasing motor vehicle accidents,⁴² lowering blood pressure, ^43,44 and decreasing the rates of myocardial infarction,³² stroke,³² and death.⁴⁵

The American Academy of Sleep Medicine recommends CPAP as an optional adjunctive therapy to lower blood pressure in patients with obstructive sleep apnea-hypopnea syndrome with concomitant hypertension.¹⁹ This is supported by a recent study that suggested that CPAP may have additional benefits on blood pressure in a subgroup of patients with uncontrolled hypertension while on antihypertensive medications.⁴⁶ Indications with Medicare guidelines for reimbursement of CPAP devices are summarized in Table 2.

Complex sleep apnea syndrome

The complex sleep apnea syndrome is characterized by the emergence of significant central sleep apnea or Cheyne-Stokes respiration after obstructive events have been brought under control with NIPPV in patients who initially appear to have obstructive sleep apnea-hypopnea syndrome. A retrospective study of patients with the complex sleep apnea syndrome who continued their NIPPV use until a subsequent polysomnographic study and NIPPV titration showed that the syndrome may resolve spontaneously, but that 46% of patients had a persistently elevated apnea-hypopnea index with central apnea activity.⁴⁷

Restoration of upper airway patency by CPAP and dysregulation or delayed adaptation of chemosensitive ventilatory control to a changing Paco₂ level may be a key pathophysiologic mechanism of the complex sleep apnea syndrome.⁴⁸ In this mechanism, increased ventilation from restored airway patency and from an increase in the slope of the ventilatory response may intermittently draw the Paco₂ to below the hypocapnic apneic threshold and trigger episodes of central apnea.⁴⁸

The ideal NIPPV device for use in the complex sleep apnea syndrome should be able to provide enough pressure to resolve the obstructive sleep apnea-hypopnea syndrome while maintaining proper ventilatory support during central apnea episodes without fluctuations of Paco₂, which could further worsen the dysregulated ventilatory control. Currently, adaptive servo-ventilation appears to be superior to bilevel PAP and CPAP in the management of the complex sleep apnea syndrome.^49,50

Sleep disturbances associated with cardiac dysfunction

There are specific indications for NIPPV modes in the setting of respiratory sleep disturbances associated with heart failure.

Obstructive sleep apnea in congestive heart failure. The prevalence of obstructive sleep apnea in patients with impaired left ventricular ejection fraction is 11% to 53%.⁵¹ Obstructive sleep apnea-hypopnea syndrome can worsen congestive heart failure by causing a periodic increase in negative intrathoracic pressure from breathing against an occluded airway, by raising arterial blood pressure, and causing tachycardia from sympathetic nervous system stimulation from hypoxia, hypercarbia, and arousals.^52,53 Both heart failure and sleep apnea contribute in an additive manner to the increased sympathetic nervous activity.⁵⁴

Fortunately, treatment with CPAP has been found to reduce systolic blood pressure and improve left ventricular systolic function in medically treated patients with heart failure and coexisting obstructive sleep apnea.^11,12 Furthermore, in a randomized trial in patients with stable congestive heart failure and newly diagnosed obstructive sleep apnea-hypopnea syndrome, a greater improvement in cardiac function was observed in patients on bilevel PAP than in those on CPAP.⁵⁵ The authors speculated that bilevel PAP might provide more unloading of the respiratory muscles, reduce the work of breathing more, and result in less positive intrathoracic pressure than with CPAP, and that the higher intrathoracic pressure with CPAP could reduce the left ventricular ejection fraction in patients with low filling pressures (pulmonary capillary wedge pressure < 12 mm Hg) and low baseline left ventricular ejection fractions (< 30%).⁵⁵

Whether these interventions reduce the mortality rate is uncertain. In a prospective nonrandomized study, 9 (24%) of 37 patients who had heart failure with untreated obstructive sleep apnea died, compared with no deaths in 14 treated patients (P = .07).⁵⁶

Cheyne-Stokes respiration with central sleep apnea in congestive heart failure. A related but different situation is central apnea associated with congestive heart failure.

There are several pathophysiologic mechanisms of Cheyne-Stokes respiration with central sleep apnea. Specifically, the elevation of left ventricular filling pressures, end-diastolic volumes, and pulmonary congestion generate hyperventilation, chronic hypocapnia, and increased chemoreceptor responsiveness, which contribute to the development of central apnea by promoting a decrease in the Paco₂ during sleep to below the hypocapnic apneic threshold.^57,58 Additionally, an increase in circulation time may result in periodicity of breathing and hyperpnea.⁵⁹ Obstructive events can then occur at the end of the central events corresponding with the nadir of the inspiratory drive.^60,61

The Canadian Continuous Positive Airway Pressure for Patients With Central Sleep Apnea and Heart Failure (CANPAP) trial, a randomized trial of CPAP in this clinical setting, showed that compared with optimal medical therapy alone, CPAP plus optimal medical therapy improved the ejection fraction, reduced central sleep apnea, improved nocturnal oxygenation, and improved the 6-minute walking distance, but without a survival benefit.⁶² The disappointing survival results from CANPAP have to be interpreted in the context that CPAP may have failed to control the central apnea in some patients, such that the mean apnea-hypopnea index in treated patients (19 events/hour) remained above the entry criterion for recruitment (15 events/hour). In a post hoc analysis of this study, the heart-transplantation-free survival rate was significantly greater in the subgroup of patients in whom CPAP effectively suppressed central sleep apnea (< 15 events/hour).⁶³

Other NIPPV modes such as bilevel PAP with backup rate and adaptive servo-ventilation have been shown in some studies to be superior to CPAP in controlling respiratory events, with adaptive servo-ventilation being the most effective in controlling central, mixed, and complex sleep apnea in this setting. ^49,50 Whether more effective resolution of obstructive and central events with these treatment modes translates into improved mortality rates and transplantation-free survival rates remains to be determined.

Obesity-hypoventilation syndrome refers to daytime hypercapnia (Paco₂ > 45 mm Hg) in obese people when no other cause of hypoventilation is present.

The prevalence of obesity-hypoventilation syndrome among patients with obstructive sleep apnea-hypopnea syndrome is 20% to 30% and is greater in extremely obese patients (body mass index > 40 kg/m²).⁶⁴ However, about 10% of patients with obesity-hypoventilation syndrome do not have obstructive sleep apnea-hypopnea syndrome.⁶⁴ Additionally, nocturnal hypoxemia and diurnal hypercapnia persist in about 40% of patients with obesity-hypoventilation syndrome after CPAP eliminates their sleep apnea.⁶⁵ Therefore, factors other than sleep apnea contribute to the development of obesity-hypoventilation syndrome, and in a meta-analysis, factors associated with daytime hypercapnia included, in addition to body mass index and the apnea-hypopnea index, mean overnight oxygen saturation and severity of restrictive pulmonary function.⁶⁶ Predictors of success with CPAP include better spirometric findings, a higher apnea-hypopnea index, and adequate oxygenation.^67,68

Bilevel PAP therapy can be tried in patients in whom CPAP by itself fails. In a study of patients with obesity-hypoventilation syndrome in whom initial CPAP treatment failed, average volume-assured pressure support lowered Paco₂ compared to bilevel PAP alone, but did not further improve oxygenation, sleep quality, or quality of life.⁶⁹

Restrictive pulmonary diseases

Neuromuscular diseases and thoracic cage abnormalities. Noninvasive ventilation has been used in patients with progressive neuromuscular disorders or severe thoracic cage abnormalities, with recognized benefits including an improved survival rate and improved quality of life.^70,71 However, NIPPV is used in only 9% of patients with amyotrophic lateral sclerosis when clearly indicated.⁷² The indications and Medicare guidelines for reimbursement of NIPPV (with or without a backup rate) in this setting are shown in Table 2.

Potential contraindications to starting NIPPV in this population include upper airway obstruction, failure to clear secretions despite optimal noninvasive support, inability to achieve a mask fit, and intolerance of the intervention.^73,74

The mechanisms of benefit of NIPPV in these settings include improvements in daytime blood gas levels (including hypercapnia⁷⁵), a reduction in the oxygen cost of breathing,⁷⁶ an increase in the ventilatory response to carbon dioxide,⁷⁵ and improved lung compliance.⁷⁷

Chronic hypercapnic failure due to severe COPD

The use of NIPPV in chronic COPD is less well established than in patients with exacerbations of COPD,⁷⁸ and limitations in its use are reflected in the more stringent Medicare indications for NIPPV in this setting (Table 2).

A particular subset of patients with stable COPD who may benefit from NIPPV includes those with daytime hypercapnia and super-imposed nocturnal hypoventilation.⁷⁸ The potential benefits of NIPPV in these patients include improved daytime and nocturnal gas exchange, increased sleep duration, and improved quality of life.⁷⁸ Additionally, a recent randomized controlled trial of NIPPV plus long-term oxygen therapy compared with oxygen therapy alone in patients with severe COPD and a Paco₂ greater than 46 mm Hg demonstrated a survival benefit in favor of adding NIPPV (hazard ratio 0.6).⁷⁹

However, that study also found no reduction in hospitalization rates, an apparent worsening in general and mental health (as reflected on the 36-Item Short Form Health Survey or SF-36, a quality-of-life questionnaire), as well as increased confusion and bewilderment (reflected on the Profile of Mood States scale).⁷⁹ These potentially deleterious effects may explain why adherence to NIPPV is low in patients with stable COPD: only 37% to 57% of patients continued to use it in several reported studies.^79–81

A level of inspiratory pressure support that is insufficient to reduce hypercapnia may account for the low adherence rate and worsened quality of life in such patients. For instance, in a randomized trial,⁸² compared with low-intensity NIPPV (mean IPAP 14 cm H₂O, backup rate 8 per minute), settings that aimed to maximally reduce Paco₂ (mean IPAP 29 cm H₂O with a backup rate of 17.5 per minute) increased the daily use of NIPPV by 3.6 hours/day and improved exercise-related dyspnea, daytime Paco₂, forced expiratory volume in 1 second (FEV₁), vital capacity, and health-related quality of life.

The overlap syndrome was first described by Flenley in 1985 as a combination of chronic respiratory disease (more generally limited to COPD) and obstructive sleep apnea-hypopnea syndrome.⁸³ Epidemiologic studies do not consistently show a higher incidence of obstructive sleep apnea-hypopnea syndrome in patients with COPD, but the exaggerated oxygen desaturation during sleep in patients with this combination increases the risk of hypoxemia, hypercapnia, and pulmonary hypertension. ⁸⁴ In addition, there was evidence of higher risks of death and of hospitalization for COPD in patients with the overlap syndrome. ⁸⁵ NIPPV is the main treatment for obstructive sleep apnea-hypopnea syndrome with or without COPD.

A recent study by Marin et al⁸⁵ showed that CPAP was associated with improved survival and decreased hospitalization in patients with the overlap syndrome. However, polysomnography or nocturnal oximetry while on NIPPV alone must be done, as additional nocturnal oxygen therapy may be warranted when significant chronic respiratory illness coexists with sleep apnea.
 

Acknowledgment: The authors gratefully acknowledge the contribution of Scott Marlow, RRT, to Table 2 of this review.

Noninvasive positive pressure ventilation (NIPPV) is any form of positive ventilatory support applied without an endotracheal tube, including continuous positive airway pressure (CPAP).¹ The role of NIPPV in acute care has been discussed in an earlier review in the Cleveland Clinic Journal of Medicine.²

NIPPV is also used at night in outpatients with stable chronic conditions, first used in the 1980s in the treatment of obstructive sleep apnea³ and neuromuscular diseases,⁴ and since then in several other conditions including sleep disorders associated with congestive heart failure (including sleep apnea and the Cheyne-Stokes respiration-central sleep apnea syndrome), chronic obstructive pulmonary disease (COPD), and the obesity-hypoventilation syndrome.

In this review, we discuss the different types of NIPPV, the specific conditions in which they can be used, and the indications, recommendations, and evidence supporting the efficacy of NIPPV in outpatients.

THE TYPES OF NIPPV AND THEIR USES

Although the conditions for which different types of NIPPV can be used overlap significantly, each type has general indications and different goals of treatment. This section begins with types of NIPPV that are predominantly used to treat sleep-disordered breathing, and then proceeds to those predominantly used for conditions associated with hypoventilation and hypercapnia.

Continuous positive airway pressure

CPAP, currently the most widely used form of NIPPV, applies a constant level of positive pressure at the airway opening during spontaneous breathing.

CPAP is commonly used to treat obstructive sleep-disordered breathing, with the goals of improving daytime sleepiness and reducing cardiovascular risk. It has also been used to treat sleep-disordered breathing associated with congestive heart failure.

CPAP’s role in the support of ventilation is limited and indirect. For instance, it has been used in the obesity-hypoventilation syndrome and in the “overlap” syndrome (in which both sleep apnea and COPD coexist). However, its benefits in those conditions are probably derived in large part from correction of underlying obstructive sleep apnea.

The mechanisms of action of CPAP include:

• Preventing intermittent narrowing and collapse of the airway in patients with obstructive sleep apnea-hypopnea syndrome by acting as a pneumatic splint during sleep^3,5,6
• Counteracting auto-positive end-expiratory pressure, thereby reducing respiratory muscle load, reducing the work of breathing, and lowering daytime Paco₂ in patients with coexistent COPD and obstructive sleep apnea-hypopnea syndrome (the overlap syndrome)^7–9
• Improving lung function (particularly the functional residual capacity) and daytime gas exchange in obstructive sleep apnea-hypopnea syndrome ¹⁰
• Improving left ventricular systolic function in patients with heart failure coexisting with obstructive sleep apnea-hypopnea syndrome.^11,12

Auto-CPAP is delivered via a self-titrating CPAP device, which uses algorithms to detect variations in the degree of obstruction and consequently adjusts the pressure level to restore normal breathing. Auto-CPAP therefore compensates for factors that modify the upper airway collapsibility, such as body posture during sleep, stage of sleep, use of alcohol, and drugs that affect upper airway muscle tone.¹³

Although one of the premises of using auto-CPAP is that it improves the patient’s satisfaction and compliance, several studies found it to be no more effective than fixed CPAP for treating obstructive sleep apnea-hypopnea syndrome.^14–16 Current guidelines of the American Academy of Sleep Medicine do not recommend self-titrating CPAP devices to diagnose obstructive sleep apnea or to treat patients with cardiopulmonary disorders or other conditions in which nocturnal desaturation may be unrelated to obstructive events.¹⁷

Adaptive servo-ventilation

Adaptive servo-ventilation was developed for Cheyne-Stokes respiration-central sleep apnea syndrome in patients with congestive heart failure, who may have periods of crescendo-decrescendo change in tidal volume (Cheyne-Stokes respiration) with possible intercalated episodes of central apnea or hypopnea. It is also applied in patients with the complex sleep apnea syndrome.

Adaptive servo-ventilation devices are usually set at an expiratory positive airway pressure (EPAP) level sufficient to control obstructive sleep apnea. The device then automatically adjusts the pressure support for each inspiration, within a prespecified range, to maintain a moving-target ventilation set at 90% of the patient’s recent average ventilation. The aim is to stabilize breathing and reduce respiratory alkalosis, which can trigger apnea reentry cycles.¹⁸

Bilevel positive airway pressure

Bilevel positive airway pressure (bilevel PAP) can be of use in sleep-disordered breathing (including cases associated with congestive heart failure), but it is predominantly applied in conditions associated with hypoventilation.

Bilevel PAP devices deliver a higher pressure during inspiration (inspiratory positive airway pressure, or IPAP) and a lower pressure during expiration (EPAP). The gradient between IPAP and EPAP is of key importance in maintaining alveolar ventilation and reducing Paco₂. The IPAP acts as pressure support to augment the patient’s effort, maintain adequate alveolar ventilation, unload respiratory muscles, decrease the work of breathing, and control obstructive hypopnea, whereas EPAP is set to maintain upper airway patency, control obstructive apnea, improve functional residual capacity, and prevent microatelectasis.

Although there is no evidence that bilevel PAP is better adhered to or more effective than CPAP, current guidelines propose it as an option for patients who require high pressures to control obstructive sleep apnea-hypopnea syndrome or for those who cannot tolerate exhaling against a high fixed CPAP pressure.¹⁹

Other, more-common uses of bilevel PAP are to treat coexisting central sleep apnea or hypoventilation,¹⁹ the obesity-hypoventilation syndrome with residual alveolar hypoventilation despite CPAP and control of concomitant obstructive sleep apnea-hypopnea syndrome,^5,20 severe stable COPD with significant nocturnal hypoventilation and daytime hypercarbia,²¹ and restrictive pulmonary diseases.²¹

Average volume-assured pressure support

CONDITIONS IN WHICH NOCTURNAL NIPPV IS USED IN OUT PATIENTS

Obstructive sleep apnea-hypopnea syndrome

Obstructive sleep apnea-hypopnea syndrome is estimated to affect 2% of women and 4% of men.²⁵ It is characterized by recurrent episodes of partial (hypopnea) or complete (apnea) upper airway obstruction during sleep despite ongoing inspiratory efforts, with associated episodes of arousal or desaturation or both. Corresponding symptoms include excessive daytime sleepiness, choking and gasping during sleep, recurrent awakenings from sleep, unrefreshing sleep, daytime fatigue, and impaired concentration that is not explained by other factors.²⁶

Current understanding of the pathophysiology of obstructive sleep apnea implicates an impairment in the balance between factors that promote collapsibility of the airway (including obesity and anatomic issues such as the volume of the soft-tissue structures surrounding the upper airway) and the compensatory neuromuscular response.^27,28

Long-standing obstructive sleep apnea-hypopnea syndrome has been linked in prospective studies to the development of hypertension,^29–31 coronary artery disease,^32,33 increased coagulation,^34,35 and stroke or death from any cause.^36,37 It is also associated with a greater rate and severity of motor vehicular accidents,³⁸ greater health care utilization, impaired work performance, and occupational injuries.³⁹

Strong evidence exists that NIPPV (most commonly CPAP) is beneficial in obstructive sleep apnea-hypopnea syndrome, improving sleep quality, sleepiness, cognitive impairment, and quality of life,^40,41 decreasing motor vehicle accidents,⁴² lowering blood pressure, ^43,44 and decreasing the rates of myocardial infarction,³² stroke,³² and death.⁴⁵

The American Academy of Sleep Medicine recommends CPAP as an optional adjunctive therapy to lower blood pressure in patients with obstructive sleep apnea-hypopnea syndrome with concomitant hypertension.¹⁹ This is supported by a recent study that suggested that CPAP may have additional benefits on blood pressure in a subgroup of patients with uncontrolled hypertension while on antihypertensive medications.⁴⁶ Indications with Medicare guidelines for reimbursement of CPAP devices are summarized in Table 2.

Complex sleep apnea syndrome

The complex sleep apnea syndrome is characterized by the emergence of significant central sleep apnea or Cheyne-Stokes respiration after obstructive events have been brought under control with NIPPV in patients who initially appear to have obstructive sleep apnea-hypopnea syndrome. A retrospective study of patients with the complex sleep apnea syndrome who continued their NIPPV use until a subsequent polysomnographic study and NIPPV titration showed that the syndrome may resolve spontaneously, but that 46% of patients had a persistently elevated apnea-hypopnea index with central apnea activity.⁴⁷

Restoration of upper airway patency by CPAP and dysregulation or delayed adaptation of chemosensitive ventilatory control to a changing Paco₂ level may be a key pathophysiologic mechanism of the complex sleep apnea syndrome.⁴⁸ In this mechanism, increased ventilation from restored airway patency and from an increase in the slope of the ventilatory response may intermittently draw the Paco₂ to below the hypocapnic apneic threshold and trigger episodes of central apnea.⁴⁸

The ideal NIPPV device for use in the complex sleep apnea syndrome should be able to provide enough pressure to resolve the obstructive sleep apnea-hypopnea syndrome while maintaining proper ventilatory support during central apnea episodes without fluctuations of Paco₂, which could further worsen the dysregulated ventilatory control. Currently, adaptive servo-ventilation appears to be superior to bilevel PAP and CPAP in the management of the complex sleep apnea syndrome.^49,50

Sleep disturbances associated with cardiac dysfunction

There are specific indications for NIPPV modes in the setting of respiratory sleep disturbances associated with heart failure.

Obstructive sleep apnea in congestive heart failure. The prevalence of obstructive sleep apnea in patients with impaired left ventricular ejection fraction is 11% to 53%.⁵¹ Obstructive sleep apnea-hypopnea syndrome can worsen congestive heart failure by causing a periodic increase in negative intrathoracic pressure from breathing against an occluded airway, by raising arterial blood pressure, and causing tachycardia from sympathetic nervous system stimulation from hypoxia, hypercarbia, and arousals.^52,53 Both heart failure and sleep apnea contribute in an additive manner to the increased sympathetic nervous activity.⁵⁴

Fortunately, treatment with CPAP has been found to reduce systolic blood pressure and improve left ventricular systolic function in medically treated patients with heart failure and coexisting obstructive sleep apnea.^11,12 Furthermore, in a randomized trial in patients with stable congestive heart failure and newly diagnosed obstructive sleep apnea-hypopnea syndrome, a greater improvement in cardiac function was observed in patients on bilevel PAP than in those on CPAP.⁵⁵ The authors speculated that bilevel PAP might provide more unloading of the respiratory muscles, reduce the work of breathing more, and result in less positive intrathoracic pressure than with CPAP, and that the higher intrathoracic pressure with CPAP could reduce the left ventricular ejection fraction in patients with low filling pressures (pulmonary capillary wedge pressure < 12 mm Hg) and low baseline left ventricular ejection fractions (< 30%).⁵⁵

Whether these interventions reduce the mortality rate is uncertain. In a prospective nonrandomized study, 9 (24%) of 37 patients who had heart failure with untreated obstructive sleep apnea died, compared with no deaths in 14 treated patients (P = .07).⁵⁶

Cheyne-Stokes respiration with central sleep apnea in congestive heart failure. A related but different situation is central apnea associated with congestive heart failure.

There are several pathophysiologic mechanisms of Cheyne-Stokes respiration with central sleep apnea. Specifically, the elevation of left ventricular filling pressures, end-diastolic volumes, and pulmonary congestion generate hyperventilation, chronic hypocapnia, and increased chemoreceptor responsiveness, which contribute to the development of central apnea by promoting a decrease in the Paco₂ during sleep to below the hypocapnic apneic threshold.^57,58 Additionally, an increase in circulation time may result in periodicity of breathing and hyperpnea.⁵⁹ Obstructive events can then occur at the end of the central events corresponding with the nadir of the inspiratory drive.^60,61

The Canadian Continuous Positive Airway Pressure for Patients With Central Sleep Apnea and Heart Failure (CANPAP) trial, a randomized trial of CPAP in this clinical setting, showed that compared with optimal medical therapy alone, CPAP plus optimal medical therapy improved the ejection fraction, reduced central sleep apnea, improved nocturnal oxygenation, and improved the 6-minute walking distance, but without a survival benefit.⁶² The disappointing survival results from CANPAP have to be interpreted in the context that CPAP may have failed to control the central apnea in some patients, such that the mean apnea-hypopnea index in treated patients (19 events/hour) remained above the entry criterion for recruitment (15 events/hour). In a post hoc analysis of this study, the heart-transplantation-free survival rate was significantly greater in the subgroup of patients in whom CPAP effectively suppressed central sleep apnea (< 15 events/hour).⁶³

Other NIPPV modes such as bilevel PAP with backup rate and adaptive servo-ventilation have been shown in some studies to be superior to CPAP in controlling respiratory events, with adaptive servo-ventilation being the most effective in controlling central, mixed, and complex sleep apnea in this setting. ^49,50 Whether more effective resolution of obstructive and central events with these treatment modes translates into improved mortality rates and transplantation-free survival rates remains to be determined.

Obesity-hypoventilation syndrome refers to daytime hypercapnia (Paco₂ > 45 mm Hg) in obese people when no other cause of hypoventilation is present.

The prevalence of obesity-hypoventilation syndrome among patients with obstructive sleep apnea-hypopnea syndrome is 20% to 30% and is greater in extremely obese patients (body mass index > 40 kg/m²).⁶⁴ However, about 10% of patients with obesity-hypoventilation syndrome do not have obstructive sleep apnea-hypopnea syndrome.⁶⁴ Additionally, nocturnal hypoxemia and diurnal hypercapnia persist in about 40% of patients with obesity-hypoventilation syndrome after CPAP eliminates their sleep apnea.⁶⁵ Therefore, factors other than sleep apnea contribute to the development of obesity-hypoventilation syndrome, and in a meta-analysis, factors associated with daytime hypercapnia included, in addition to body mass index and the apnea-hypopnea index, mean overnight oxygen saturation and severity of restrictive pulmonary function.⁶⁶ Predictors of success with CPAP include better spirometric findings, a higher apnea-hypopnea index, and adequate oxygenation.^67,68

Bilevel PAP therapy can be tried in patients in whom CPAP by itself fails. In a study of patients with obesity-hypoventilation syndrome in whom initial CPAP treatment failed, average volume-assured pressure support lowered Paco₂ compared to bilevel PAP alone, but did not further improve oxygenation, sleep quality, or quality of life.⁶⁹

Restrictive pulmonary diseases

Neuromuscular diseases and thoracic cage abnormalities. Noninvasive ventilation has been used in patients with progressive neuromuscular disorders or severe thoracic cage abnormalities, with recognized benefits including an improved survival rate and improved quality of life.^70,71 However, NIPPV is used in only 9% of patients with amyotrophic lateral sclerosis when clearly indicated.⁷² The indications and Medicare guidelines for reimbursement of NIPPV (with or without a backup rate) in this setting are shown in Table 2.

Potential contraindications to starting NIPPV in this population include upper airway obstruction, failure to clear secretions despite optimal noninvasive support, inability to achieve a mask fit, and intolerance of the intervention.^73,74

The mechanisms of benefit of NIPPV in these settings include improvements in daytime blood gas levels (including hypercapnia⁷⁵), a reduction in the oxygen cost of breathing,⁷⁶ an increase in the ventilatory response to carbon dioxide,⁷⁵ and improved lung compliance.⁷⁷

Chronic hypercapnic failure due to severe COPD

The use of NIPPV in chronic COPD is less well established than in patients with exacerbations of COPD,⁷⁸ and limitations in its use are reflected in the more stringent Medicare indications for NIPPV in this setting (Table 2).

A particular subset of patients with stable COPD who may benefit from NIPPV includes those with daytime hypercapnia and super-imposed nocturnal hypoventilation.⁷⁸ The potential benefits of NIPPV in these patients include improved daytime and nocturnal gas exchange, increased sleep duration, and improved quality of life.⁷⁸ Additionally, a recent randomized controlled trial of NIPPV plus long-term oxygen therapy compared with oxygen therapy alone in patients with severe COPD and a Paco₂ greater than 46 mm Hg demonstrated a survival benefit in favor of adding NIPPV (hazard ratio 0.6).⁷⁹

However, that study also found no reduction in hospitalization rates, an apparent worsening in general and mental health (as reflected on the 36-Item Short Form Health Survey or SF-36, a quality-of-life questionnaire), as well as increased confusion and bewilderment (reflected on the Profile of Mood States scale).⁷⁹ These potentially deleterious effects may explain why adherence to NIPPV is low in patients with stable COPD: only 37% to 57% of patients continued to use it in several reported studies.^79–81

A level of inspiratory pressure support that is insufficient to reduce hypercapnia may account for the low adherence rate and worsened quality of life in such patients. For instance, in a randomized trial,⁸² compared with low-intensity NIPPV (mean IPAP 14 cm H₂O, backup rate 8 per minute), settings that aimed to maximally reduce Paco₂ (mean IPAP 29 cm H₂O with a backup rate of 17.5 per minute) increased the daily use of NIPPV by 3.6 hours/day and improved exercise-related dyspnea, daytime Paco₂, forced expiratory volume in 1 second (FEV₁), vital capacity, and health-related quality of life.

The overlap syndrome was first described by Flenley in 1985 as a combination of chronic respiratory disease (more generally limited to COPD) and obstructive sleep apnea-hypopnea syndrome.⁸³ Epidemiologic studies do not consistently show a higher incidence of obstructive sleep apnea-hypopnea syndrome in patients with COPD, but the exaggerated oxygen desaturation during sleep in patients with this combination increases the risk of hypoxemia, hypercapnia, and pulmonary hypertension. ⁸⁴ In addition, there was evidence of higher risks of death and of hospitalization for COPD in patients with the overlap syndrome. ⁸⁵ NIPPV is the main treatment for obstructive sleep apnea-hypopnea syndrome with or without COPD.

A recent study by Marin et al⁸⁵ showed that CPAP was associated with improved survival and decreased hospitalization in patients with the overlap syndrome. However, polysomnography or nocturnal oximetry while on NIPPV alone must be done, as additional nocturnal oxygen therapy may be warranted when significant chronic respiratory illness coexists with sleep apnea.
 

Acknowledgment: The authors gratefully acknowledge the contribution of Scott Marlow, RRT, to Table 2 of this review.