Mechanisms of obstructive sleep apnea

Abstract

CT = computed tomography; EMG electromyogram1 MRI = magnetic resonance imaging; NREM nonrapid eye movement OSA = obstructive sleep apnea; REM rapid eye movement O bstructive sleep apnea (OSA) is characterized by intermittent inspiratory closure of the pharyn-geal airway during sleep resulting in episodic hypoxe-mia and sleep disruption. Primary presenting symp-toms are heavy snoring and excessive daytime sleepiness. Investigations conducted in the late 1970s and 1980s have enhanced our understanding of the etiology ofOSA, but to date no single pathophysiologic mechanism has been identified. Thus, it is possible that the cause of OSA is multifactorial in any one individual or differs in different patients. At the conclusion, schema illustrating the importance of etiologic components and their interaction will be shown. The following are categories of individual factors known to contribute to upper airway obstruction during sleep: (1) anatomic narrowing of the upper airway; (2) increased compliance or collapsibility of upper airway tissues; (3) reflexes affecting upper airway caliber; and (4) pharyngeal inspiratory muscle function. In this review, a critique of significant research developments addressing the pathophysiol-ogy of OSA will be presented