COPD and Sleep Apnea Overlap

Excerpt

The overlap syndrome, introduced by David C. Flenely in 1985, characterizes the combination of obstructive sleep apnea (OSA) with respiratory disorders such as chronic obstructive pulmonary disease (COPD). COPD involves persistent respiratory symptoms and irreversible distal airflow limitation. Individuals with COPD frequently experience challenges in initiating sleep and frequent nighttime arousals, leading to poor sleep quality and excessive daytime fatigue.

Nocturnal hypoxia and hypoventilation associated with COPD generally occur during rapid eye movement (REM) sleep, stemming from reduced chest wall motility and the relaxation of intercostal muscles. Conversely, patients with OSA experience frequent nighttime arousals and excessive daytime sleepiness due to upper airway collapse, reduced intrathoracic pressures, and activation of the sympathetic nervous system.

Patients affected by overlap syndrome exhibit higher levels of nocturnal oxygen desaturations than those with COPD or OSA alone, heightening their risk of cardiovascular events, including pulmonary hypertension, right heart failure, and atrial fibrillation. The overlapping presentation of COPD and OSA complicates diagnosis and treatment. Given the increased morbidity and mortality associated with overlap syndrome, healthcare professionals must be aware of this condition for timely recognition and treatment.

With the increasing prevalence of COPD and OSA, studies suggest that 1 out of 10 individuals with 1 condition will also have the other disorder, by chance alone. However, whether the prevalence of OSA is higher in patients with COPD than in the general population is debatable, as some studies show no increase. Conversely, others have identified a high prevalence of OSA in patients with moderate to severe COPD referred to pulmonary rehabilitation.