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Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) each affect at least 10% of the general adult population and, thus, both disorders together, commonly referred to as the overlap syndrome, could be expected in at least 1% of adults by chance alone. However, there is evidence of important interactions between the disorders that influence the prevalence of the overlap, which have implications for the development of comorbidities,and also for management (McNicholas WT. Chest. 2017; 152[6]:1318). Furthermore, sleep quality is typically poor in COPD, which has been linked to worse pulmonary function and lung hyperinflation and may contribute to daytime fatigue.
Interactions between COPD and OSA that may influence the prevalence of overlap
Previous reports have presented conflicting results regarding the likely association between COPD and OSA, which may partly reflect different definitions of OSA, patient populations, and methodologies of investigation. However, COPD represents a spectrum of clinical phenotypes ranging from the hyperinflated patient with low BMI (predominant emphysema phenotype) to the patient with higher BMI and tendency to right-sided heart failure (predominant chronic bronchitis phenotype). The predominant emphysema phenotype may predispose to a lower likelihood of OSA, and there is recent evidence that lung hyperinflation is protective against the development of OSA by lowering the critical closing pressure of the upper airway during sleep. Furthermore, the degree of emphysema and gas trapping on CT scan of the thorax correlates inversely with apnea-hypopnia index in patients with severe COPD (Krachman SL et al. Ann Am Thorac Soc. 2016;13[7]:1129).
In contrast, the predominant chronic bronchitis phenotype predisposes to a higher likelihood of OSA because of higher BMI and likelihood of right-sided heart failure. Peripheral fluid retention in such patients predisposes to OSA because of the rostral fluid shift that occurs during sleep in the supine position, predisposing to upper airway obstruction by airway narrowing. The COPDGene study reports that the chronic bronchitis phenotype has a higher prevalence of OSA even in the absence of differences in BMI and lung function (Kim V et al. Chest. 2011;140[3]:626). Upper airway inflammation associated with cigarette smoking may also contribute to the development of OSA, and corticosteroid therapy may adversely affect upper airway muscle function. OSA also appears to exacerbate lower airway inflammation in COPD. In practice, most patients with COPD have a mixture of emphysema and chronic bronchitis, and the probability of OSA will represent the balance of these protective and promoting factors in individual patients (Fig 1).
While there is evidence of increased mortality in patients with COPD and OSA alone, a recent report based on the Sleep Heart Health Study somewhat surprisingly found that the incremental contribution of declining lung function to mortality diminished with increasing severity of SDB measured by AHI (Putcha N et al. Am J Respir Crit Care Med. 2016;194[8]:1007). Thus, the epidemiologic relationship of COPD and OSA and related clinical outcomes remains an important research topic comparing different clinical phenotypes.
Mechanisms of interaction in the overlap syndrome and implications for comorbidity
COPD and OSA are associated with several overlapping physiological and biological disturbances, including hypoxia and inflammation, which may contribute to cardiovascular and other comorbidities. Thus, the probability should be high that the overlap syndrome will be associated with a greater risk of comorbidity than with either disease alone. Patients with the overlap syndrome demonstrate greater degrees of oxygen desaturation predisposing to pulmonary hypertension, which is especially common in these patients.
COPD and OSA are each associated with systemic inflammation and oxidative stress, and C-reactive protein (CRP) has been identified as a measure of systemic inflammation that is commonly elevated in both disorders, although in OSA, concurrent obesity is an important confounding factor. Systemic inflammation contributes to the development of cardiovascular disease, which is a common complication of both COPD and OSA. Thus, one could expect that cardiovascular disease is particularly prevalent in patients with overlap syndrome, but there are limited data on this relationship, which represents an important research topic.
Clinical assessment
Patients with the overlap syndrome present with typical clinical features of each disorder and additional features that reflect the higher prevalence of hypoxemia, hypercapnia, and pulmonary hypertension. Thus, morning headaches reflecting hypercapnia and peripheral edema reflecting right-sided heart failure may be especially common. Screening questionnaires may be helpful in the initial evaluation of likely OSA in patients with COPD, and objective clinical data, including anthropometrics such as age, sex, and BMI, and medical history such as cardiovascular comorbidity, are especially useful in clinical prediction (McNicholas WT. Lancet Respir Med. 2016;4[9]:683). Thus, screening for OSA in patients with COPD should not be complicated, and the widespread failure to do so may reflect a lack of awareness of the possible association by the clinician involved.
The specific diagnosis of OSA in COPD requires some form of overnight sleep study, and there is a growing move toward ambulatory studies that focus on cardiorespiratory variables. Overnight monitoring of oxygen saturation is especially useful, particularly if linked to special analysis software, and may be sufficient in many cases. Full polysomnography can be reserved for select cases where the diagnosis remains in doubt.
Management and outcomes
Nocturnal hypoxemia in patients with COPD benefits from inhaled, long-acting beta-agonist and anticholinergic therapy, and mean nocturnal oxygen saturation is 2% to 3% higher on each medication compared with placebo. Supplemental oxygen may be indicated when nocturnal oxygen desaturation persists despite optimum pharmacotherapy and does not appear to be associated with significant additional risk of hypercapnia.
However, in patients with COPD-OSA overlap, nonnvasive pressure support is the most appropriate management option. In patients with predominant OSA, continuous positive airway pressure therapy (CPAP) is the preferred option, but where COPD is the dominant component, noninvasive ventilation (NIV) in the form of bi-level positive airway pressure (BIPAP) may be more appropriate. Recent reports in severe COPD indicate that NIV targeted to markedly reduce hypercapnia is associated with improved quality of life and prolonged survival (Köhnlein T et al. Lancet Respir Med. 2014;2[9]:698), and patients with COPD with persistent hypercapnia following hospitalization with an acute exacerbation show improved clinical outcomes and survival with continuing home NIV (Murphy PB et al. JAMA. 2017;317[21]:2177).
The recognition of co-existing OSA in patients with COPD has important clinical relevance as the management of patients with overlap syndrome is different from COPD alone, and the long-term survival of patients with overlap syndrome not treated with nocturnal positive airway pressure is significantly inferior to those patients with overlap syndrome appropriately treated (Marin JM et al. Am J Respir Crit Care Med. 2010;182[3]:325).
Dr. McNicholas is with the Department of Respiratory and Sleep Medicine, St. Vincent’s University Hospital, Dublin School of Medicine, University College Dublin, Ireland.
Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) each affect at least 10% of the general adult population and, thus, both disorders together, commonly referred to as the overlap syndrome, could be expected in at least 1% of adults by chance alone. However, there is evidence of important interactions between the disorders that influence the prevalence of the overlap, which have implications for the development of comorbidities,and also for management (McNicholas WT. Chest. 2017; 152[6]:1318). Furthermore, sleep quality is typically poor in COPD, which has been linked to worse pulmonary function and lung hyperinflation and may contribute to daytime fatigue.
Interactions between COPD and OSA that may influence the prevalence of overlap
Previous reports have presented conflicting results regarding the likely association between COPD and OSA, which may partly reflect different definitions of OSA, patient populations, and methodologies of investigation. However, COPD represents a spectrum of clinical phenotypes ranging from the hyperinflated patient with low BMI (predominant emphysema phenotype) to the patient with higher BMI and tendency to right-sided heart failure (predominant chronic bronchitis phenotype). The predominant emphysema phenotype may predispose to a lower likelihood of OSA, and there is recent evidence that lung hyperinflation is protective against the development of OSA by lowering the critical closing pressure of the upper airway during sleep. Furthermore, the degree of emphysema and gas trapping on CT scan of the thorax correlates inversely with apnea-hypopnia index in patients with severe COPD (Krachman SL et al. Ann Am Thorac Soc. 2016;13[7]:1129).
In contrast, the predominant chronic bronchitis phenotype predisposes to a higher likelihood of OSA because of higher BMI and likelihood of right-sided heart failure. Peripheral fluid retention in such patients predisposes to OSA because of the rostral fluid shift that occurs during sleep in the supine position, predisposing to upper airway obstruction by airway narrowing. The COPDGene study reports that the chronic bronchitis phenotype has a higher prevalence of OSA even in the absence of differences in BMI and lung function (Kim V et al. Chest. 2011;140[3]:626). Upper airway inflammation associated with cigarette smoking may also contribute to the development of OSA, and corticosteroid therapy may adversely affect upper airway muscle function. OSA also appears to exacerbate lower airway inflammation in COPD. In practice, most patients with COPD have a mixture of emphysema and chronic bronchitis, and the probability of OSA will represent the balance of these protective and promoting factors in individual patients (Fig 1).
While there is evidence of increased mortality in patients with COPD and OSA alone, a recent report based on the Sleep Heart Health Study somewhat surprisingly found that the incremental contribution of declining lung function to mortality diminished with increasing severity of SDB measured by AHI (Putcha N et al. Am J Respir Crit Care Med. 2016;194[8]:1007). Thus, the epidemiologic relationship of COPD and OSA and related clinical outcomes remains an important research topic comparing different clinical phenotypes.
Mechanisms of interaction in the overlap syndrome and implications for comorbidity
COPD and OSA are associated with several overlapping physiological and biological disturbances, including hypoxia and inflammation, which may contribute to cardiovascular and other comorbidities. Thus, the probability should be high that the overlap syndrome will be associated with a greater risk of comorbidity than with either disease alone. Patients with the overlap syndrome demonstrate greater degrees of oxygen desaturation predisposing to pulmonary hypertension, which is especially common in these patients.
COPD and OSA are each associated with systemic inflammation and oxidative stress, and C-reactive protein (CRP) has been identified as a measure of systemic inflammation that is commonly elevated in both disorders, although in OSA, concurrent obesity is an important confounding factor. Systemic inflammation contributes to the development of cardiovascular disease, which is a common complication of both COPD and OSA. Thus, one could expect that cardiovascular disease is particularly prevalent in patients with overlap syndrome, but there are limited data on this relationship, which represents an important research topic.
Clinical assessment
Patients with the overlap syndrome present with typical clinical features of each disorder and additional features that reflect the higher prevalence of hypoxemia, hypercapnia, and pulmonary hypertension. Thus, morning headaches reflecting hypercapnia and peripheral edema reflecting right-sided heart failure may be especially common. Screening questionnaires may be helpful in the initial evaluation of likely OSA in patients with COPD, and objective clinical data, including anthropometrics such as age, sex, and BMI, and medical history such as cardiovascular comorbidity, are especially useful in clinical prediction (McNicholas WT. Lancet Respir Med. 2016;4[9]:683). Thus, screening for OSA in patients with COPD should not be complicated, and the widespread failure to do so may reflect a lack of awareness of the possible association by the clinician involved.
The specific diagnosis of OSA in COPD requires some form of overnight sleep study, and there is a growing move toward ambulatory studies that focus on cardiorespiratory variables. Overnight monitoring of oxygen saturation is especially useful, particularly if linked to special analysis software, and may be sufficient in many cases. Full polysomnography can be reserved for select cases where the diagnosis remains in doubt.
Management and outcomes
Nocturnal hypoxemia in patients with COPD benefits from inhaled, long-acting beta-agonist and anticholinergic therapy, and mean nocturnal oxygen saturation is 2% to 3% higher on each medication compared with placebo. Supplemental oxygen may be indicated when nocturnal oxygen desaturation persists despite optimum pharmacotherapy and does not appear to be associated with significant additional risk of hypercapnia.
However, in patients with COPD-OSA overlap, nonnvasive pressure support is the most appropriate management option. In patients with predominant OSA, continuous positive airway pressure therapy (CPAP) is the preferred option, but where COPD is the dominant component, noninvasive ventilation (NIV) in the form of bi-level positive airway pressure (BIPAP) may be more appropriate. Recent reports in severe COPD indicate that NIV targeted to markedly reduce hypercapnia is associated with improved quality of life and prolonged survival (Köhnlein T et al. Lancet Respir Med. 2014;2[9]:698), and patients with COPD with persistent hypercapnia following hospitalization with an acute exacerbation show improved clinical outcomes and survival with continuing home NIV (Murphy PB et al. JAMA. 2017;317[21]:2177).
The recognition of co-existing OSA in patients with COPD has important clinical relevance as the management of patients with overlap syndrome is different from COPD alone, and the long-term survival of patients with overlap syndrome not treated with nocturnal positive airway pressure is significantly inferior to those patients with overlap syndrome appropriately treated (Marin JM et al. Am J Respir Crit Care Med. 2010;182[3]:325).
Dr. McNicholas is with the Department of Respiratory and Sleep Medicine, St. Vincent’s University Hospital, Dublin School of Medicine, University College Dublin, Ireland.
Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) each affect at least 10% of the general adult population and, thus, both disorders together, commonly referred to as the overlap syndrome, could be expected in at least 1% of adults by chance alone. However, there is evidence of important interactions between the disorders that influence the prevalence of the overlap, which have implications for the development of comorbidities,and also for management (McNicholas WT. Chest. 2017; 152[6]:1318). Furthermore, sleep quality is typically poor in COPD, which has been linked to worse pulmonary function and lung hyperinflation and may contribute to daytime fatigue.
Interactions between COPD and OSA that may influence the prevalence of overlap
Previous reports have presented conflicting results regarding the likely association between COPD and OSA, which may partly reflect different definitions of OSA, patient populations, and methodologies of investigation. However, COPD represents a spectrum of clinical phenotypes ranging from the hyperinflated patient with low BMI (predominant emphysema phenotype) to the patient with higher BMI and tendency to right-sided heart failure (predominant chronic bronchitis phenotype). The predominant emphysema phenotype may predispose to a lower likelihood of OSA, and there is recent evidence that lung hyperinflation is protective against the development of OSA by lowering the critical closing pressure of the upper airway during sleep. Furthermore, the degree of emphysema and gas trapping on CT scan of the thorax correlates inversely with apnea-hypopnia index in patients with severe COPD (Krachman SL et al. Ann Am Thorac Soc. 2016;13[7]:1129).
In contrast, the predominant chronic bronchitis phenotype predisposes to a higher likelihood of OSA because of higher BMI and likelihood of right-sided heart failure. Peripheral fluid retention in such patients predisposes to OSA because of the rostral fluid shift that occurs during sleep in the supine position, predisposing to upper airway obstruction by airway narrowing. The COPDGene study reports that the chronic bronchitis phenotype has a higher prevalence of OSA even in the absence of differences in BMI and lung function (Kim V et al. Chest. 2011;140[3]:626). Upper airway inflammation associated with cigarette smoking may also contribute to the development of OSA, and corticosteroid therapy may adversely affect upper airway muscle function. OSA also appears to exacerbate lower airway inflammation in COPD. In practice, most patients with COPD have a mixture of emphysema and chronic bronchitis, and the probability of OSA will represent the balance of these protective and promoting factors in individual patients (Fig 1).
While there is evidence of increased mortality in patients with COPD and OSA alone, a recent report based on the Sleep Heart Health Study somewhat surprisingly found that the incremental contribution of declining lung function to mortality diminished with increasing severity of SDB measured by AHI (Putcha N et al. Am J Respir Crit Care Med. 2016;194[8]:1007). Thus, the epidemiologic relationship of COPD and OSA and related clinical outcomes remains an important research topic comparing different clinical phenotypes.
Mechanisms of interaction in the overlap syndrome and implications for comorbidity
COPD and OSA are associated with several overlapping physiological and biological disturbances, including hypoxia and inflammation, which may contribute to cardiovascular and other comorbidities. Thus, the probability should be high that the overlap syndrome will be associated with a greater risk of comorbidity than with either disease alone. Patients with the overlap syndrome demonstrate greater degrees of oxygen desaturation predisposing to pulmonary hypertension, which is especially common in these patients.
COPD and OSA are each associated with systemic inflammation and oxidative stress, and C-reactive protein (CRP) has been identified as a measure of systemic inflammation that is commonly elevated in both disorders, although in OSA, concurrent obesity is an important confounding factor. Systemic inflammation contributes to the development of cardiovascular disease, which is a common complication of both COPD and OSA. Thus, one could expect that cardiovascular disease is particularly prevalent in patients with overlap syndrome, but there are limited data on this relationship, which represents an important research topic.
Clinical assessment
Patients with the overlap syndrome present with typical clinical features of each disorder and additional features that reflect the higher prevalence of hypoxemia, hypercapnia, and pulmonary hypertension. Thus, morning headaches reflecting hypercapnia and peripheral edema reflecting right-sided heart failure may be especially common. Screening questionnaires may be helpful in the initial evaluation of likely OSA in patients with COPD, and objective clinical data, including anthropometrics such as age, sex, and BMI, and medical history such as cardiovascular comorbidity, are especially useful in clinical prediction (McNicholas WT. Lancet Respir Med. 2016;4[9]:683). Thus, screening for OSA in patients with COPD should not be complicated, and the widespread failure to do so may reflect a lack of awareness of the possible association by the clinician involved.
The specific diagnosis of OSA in COPD requires some form of overnight sleep study, and there is a growing move toward ambulatory studies that focus on cardiorespiratory variables. Overnight monitoring of oxygen saturation is especially useful, particularly if linked to special analysis software, and may be sufficient in many cases. Full polysomnography can be reserved for select cases where the diagnosis remains in doubt.
Management and outcomes
Nocturnal hypoxemia in patients with COPD benefits from inhaled, long-acting beta-agonist and anticholinergic therapy, and mean nocturnal oxygen saturation is 2% to 3% higher on each medication compared with placebo. Supplemental oxygen may be indicated when nocturnal oxygen desaturation persists despite optimum pharmacotherapy and does not appear to be associated with significant additional risk of hypercapnia.
However, in patients with COPD-OSA overlap, nonnvasive pressure support is the most appropriate management option. In patients with predominant OSA, continuous positive airway pressure therapy (CPAP) is the preferred option, but where COPD is the dominant component, noninvasive ventilation (NIV) in the form of bi-level positive airway pressure (BIPAP) may be more appropriate. Recent reports in severe COPD indicate that NIV targeted to markedly reduce hypercapnia is associated with improved quality of life and prolonged survival (Köhnlein T et al. Lancet Respir Med. 2014;2[9]:698), and patients with COPD with persistent hypercapnia following hospitalization with an acute exacerbation show improved clinical outcomes and survival with continuing home NIV (Murphy PB et al. JAMA. 2017;317[21]:2177).
The recognition of co-existing OSA in patients with COPD has important clinical relevance as the management of patients with overlap syndrome is different from COPD alone, and the long-term survival of patients with overlap syndrome not treated with nocturnal positive airway pressure is significantly inferior to those patients with overlap syndrome appropriately treated (Marin JM et al. Am J Respir Crit Care Med. 2010;182[3]:325).
Dr. McNicholas is with the Department of Respiratory and Sleep Medicine, St. Vincent’s University Hospital, Dublin School of Medicine, University College Dublin, Ireland.