Pathophysiology of obstructive sleep apnea

Abstract

Obstructive sleep apnea (OSA) is a common sleep disorder that is characterized by recurrent episodes of upper airway obstruction and is associated with reductions in ventilation, resulting in recurrent arousals and episodic oxyhemoglobin desaturations during sleep. Fundamental understanding of the pathophysiology and knowledge of common patterns of OSA may help to identify patients and guide therapy. The major risk factors for the disorder include obesity, male gender, hormones, age, anatomical factors, genetic factors, posture, and gravity. The pathophysiology of OSA is summarized in three steps: firstly, the varied structural and functional determinants of an anatomical predisposition for airway closure, an absolutely essential component for OSA; secondly, the effects of the sleep itself, which emphasizes on mechanisms underlying apnea and ventilatory instability; and, thirdly, the integration of anatomical deficits with mechanisms underlying central neurochemical control of breathing stability and compensatory neuromuscular control of upper airway caliber. These mechanisms are discussed with an emphasis on understanding the physiology and pathophysiology of OSA better, which are believed to be some of the essential knowledge for the proper management of this multifaceted and complex disorder. The main focus is the key pathophysiological factors and their interactions, to highlight recent innovations in our understanding of OSA pathogenesis.