Advanced Concepts in the Pathophysiology of Obstructive Sleep Apnea.

The primary pathological event in the disorder obstructive sleep apnea (OSA) is the partial or complete closure of the pharyngeal airway during sleep in an individual with a widely patent airway during wakefulness. This yields an apnea or hypopnea with resulting hypoxia and hypercapnia, and most often requires an arousal to terminate the event. These events occur in a repetitive manner during sleep, yielding intermittent hypoxia and sleep fragmentation with their associated adverse effects on the health and quality of life of the afflicted individual. Here, we focus on the events leading up to these apneas and hypopneas, primarily addressing pharyngeal anatomy, upper airway muscle control, the respiratory arousal threshold, and ventilatory control instability in OSA pathophysiology.