Obstructive sleep apnea syndrome.

Obstructive sleep apnea syndrome is caused by upper airway collapse during inspiration, causing intermittent hypoxemia, hypercapnia, acidosis, sympathetic nervous system activation, and arousal from sleep. Nighttime blood pressure is higher, but unexpectedly, daytime hypertension occurs. The prevalence of hypertension is very high and the incidence of hypertension increases as the number of apneic and hypopneic events per hour rises. Obesity is a major predisposing factor for the development of obstructive sleep apnea. Daytime sleepiness, snoring, and breathing pauses are important symptoms to elicit from the patient or sleep partner. Resistant hypertension is an important clue. Overnight polysomnography is required for diagnosis. Weight loss, avoidance of nocturnal sedatives, cessation of evening alcohol ingestion, and avoidance of the supine position during sleep are initial therapeutic actions in mild obstructive sleep apnea syndrome. Continuous positive airway pressure is the treatment of choice for patients unable to find relief from lifestyle changes. Blood pressure modestly improves with treatment.