Respiratory irregularities normally occur during sleep. In populations afflicted with obstructive sleep apnea (OSA) or chronic pulmonary disease (COPD), these breathing irregularities become more pronounced and subsequently lead to adverse effects on health. Overlap syndrome (OS) is defined as the co-existence of COPD and OSA in the same patient. Patients with overlap syndrome have a worse prognosis compared to those with either COPD or OSA alone. The purpose of this report is to describe the pathophysiology of COPD and OSA, as each disease process contributes uniquely to the development of OS. We also describe the epidemiology, clinical presentation, diagnosis, prognosis, and treatment of OS. The diagnosis of OS is challenging due to variable clinical presentations. Symptoms such as fatigue, are subtle and non-specific; therefore, clinicians should have a high index of suspicion for diagnosis. Diagnostic tools include pulmonary function tests to confirm chronic obstruction as well as polysomnography to evaluate breathing patterns during sleep. Presence of apneas and hypopneas associated with concomitant arousals and hypoxia, contribute to the diagnosis of sleep apnea in COPD patients. Clinicians should treat overlap syndrome by optimizing bronchodilator therapy for COPD and administering continuous positive airway pressure with or without supplemental oxygen during sleep. Prompt diagnosis and treatment benefits the patient not only by providing practical relief from symptoms such as daytime fatigue; more importantly, treatment of OS significantly impacts health by helping to reduce cardiovascular complications.
Keywords: Obstructive sleep apnea, chronic obstructive pulmonary disease, overlap syndrome, continuous positive airway pressure