Mechanisms of Pharyngeal Collapse in Sleep Apnea, Study B

The mechanisms that lead to airway closure in OSA are not completely understood. Some studies have shown that there is progressive narrowing of the pharyngeal airway across breaths during expiration (Progressive Expiratory Narrowing, PEN) preceding an obstructive apnea. The investigators will test if lung volumes and low respiratory drive play a role in PEN. To this end, the investigators will visualize the pharynx of sleep apnea patients during sleep using a thin endoscope during sleep while simultaneously measuring lung volumes, genioglossus electromyogram, and pharyngeal pressure during flow-limited breaths. Flow limitation will be induced by sustained reductions of continuous positive airway pressure (CPAP).