[The overlap syndrome: obstructive sleep apnea and chronic obstructive pulmonary disease].

Overlap syndrome is a term which specifies the existence of both chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) in the same patient. The prevalence of OSA in COPD patients equals its prevalence in the general population. Overlap patients have a greater degree of hypoxemia and hypercapnea than COPD patients matched for stage. They also have a greater prevalence of pulmonary hypertension and right heart failure, and suffer higher morbidity. Due to these consequences of the overlap syndrome, it is recommended to actively search for its existence in COPD patients, and to treat it with continuous positive airway pressure (CPAP) concurrently with oxygen and optimal pharmacological treatment of COPD.