Obstructive sleep apnea (OSA) is a highly prevalent disease characterized by recurrent episodes of upper airway obstruction that result in recurrent arousals and episodic oxyhemoglobin desaturations during sleep. Significant clinical consequences of the disorder cover a wide spectrum, including daytime hypersomnolence, neurocognitive dysfunction, cardiovascular disease, metabolic dysfunction, and cor pulmonale. The major risk factors for the disorder include obesity, male gender, and age. Current understanding of the pathophysiologic basis of the disorder suggests that a balance of anatomically imposed mechanical loads and compensatory neuromuscular responses are important in maintaining upper airway patency during sleep. OSA develops in the presence of both elevated mechanical loads on the upper airway and defects in compensatory neuromuscular responses. A sleep history and physical examination is important in identification of patients and appropriate referral for polysomnography. Understanding nuances in the spectrum of presenting complaints and polysomnography correlates are important for diagnostic and therapeutic approaches. Knowledge of common patterns of OSA may help to identify patients and guide therapy.Keywords critical pressure; diagnosis; obstructive sleep apnea; pathophysiology Obstructive sleep apnea (OSA) is a highly prevalent disease, affecting 4% of men and 2% of women, 1 and strongly linked to the current obesity epidemic. The disorder 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.2 Significant clinical consequences of the disorder cover a wide spectrum including daytime hypersomnolence,3 , 4 neurocognitive dysfunction, 5 cardiovascular disease (hypertension, stroke, myocardial infarction, heart failure), 6, 7 metabolic dysfunction,8 -10 respiratory failure, and cor pulmonale. 11 The major risk factors for the disorder include obesity, male gender, postmeno-pausal status, and age, and are discussed in detail elsewhere. [12][13][14] The rising prevalence of obesity in the United States suggests that OSA will represent an escalating public health burden. 15 Therefore, knowledge and understanding of the pathogenic basis, clinical presentation, and diagnosis of OSA are essential for the development of preventive, screening, and therapeutic strategies to reduce the public health burden of the disorder. In this review, we * The manuscript was supported by grants HL50381, HL37379, and HL77137 from the National Heart, Lung, Blood Institute, National
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Author ManuscriptChest. Author manuscript; available in PMC 2010 January 29.
Published in final edited form as:Chest.
Pathophysiology of Upper Airway Obstruction in OSAThe pharynx is a complex structure that serves several purposes including speech, swallowing, and respiration. The human pharynx is composed of > 20 muscles and divided into four sections that include the nas...