Chest
Volume 132, Issue 1, July 2007, Pages 325-337
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POSTGRADUATE EDUCATION CORNER
CONTEMPORARY REVIEWS IN SLEEP MEDICINE
Adult Obstructive Sleep Apnea: Pathophysiology and Diagnosis

https://doi.org/10.1378/chest.07-0040Get rights and content

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.

Section snippets

Pathophysiology of Upper Airway Obstruction in OSA

The 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 nasopharynx (from the nasal turbinates to the start of the soft palate), velopharynx (from the start of the soft palate to the tip of the uvula), oropharynx (from the tip of the uvula to the tip of the epiglottis), and hypopharynx (from the tip of the epiglottis to the level of the vocal

Clinical Presentation

The classic signs and symptoms for OSA include signs of upper airway obstruction during sleep, insomnia, and daytime hypersomnolence in the setting of obesity; however, a broad range of symptoms can be reported (Table 1). Generally, these symptoms develop over years and progress in association with increases in weight, aging, or transition to menopause. A detailed longitudinal sleep history and physical examination are essential in identifying at-risk individuals because as many as 90% of cases

Risk Stratification for Appropriate Referral for Polysomnography

Appropriate referral by the physician for a sleep study begins with the history and physical examination. Clinical impression using a combination of symptoms, physical examination findings, and other objective data has been used to risk stratify patients for appropriate referral to a sleep laboratory. Obesity, in a population of middle-aged men from the community resulted in an OSA prevalence of > 50%.88 Snoring, while associated with a higher prevalence of OSA, only has a positive predictive

Summary

OSA is a common sleep disorder that can present in a variety of ways in the pulmonary physician's office. With a fundamental understanding of the pathophysiology of OSA, the pulmonary physician can routinely integrate questions into their review of system that will assist in appropriate referral for polysomnography and diagnosis of the disorder. Understanding nuances in the spectrum of presenting complaints and polysomnography correlates are important for diagnostic and therapeutic purposes.

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    The manuscript was supported by grants HL50381, HL37379, and HL77137 from the National Heart, Lung, Blood Institute, National Institutes of Health.

    No financial or other potential conflicts of interest exist for all the authors.

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