Population-based studies have estimated that 4 percent of men and 2 percent of women between 30 and 60 years of age have obstructive sleep apnea that is significant enough to cause daytime somnolence. Despite this prevalence, the condition often remains undiagnosed because of its nonspecific symptoms. Flemons reviews sleep apnea and offers an algorithm for pursuing the diagnosis.
Clinical clues that should lead to a suspicion of sleep apnea include snoring, obesity, hypertension, and daytime somnolence. Of course, sleep apnea is not the only sleep disorder that can cause daytime sleepiness. In the differential diagnosis, the author includes insufficient sleep, circadian rhythm abnormalities (e.g., shift workers), periodic limb movements during sleep, and narcolepsy.
Although polysomnography in a sleep laboratory is the gold standard in the diagnosis of sleep apnea, its expense and lack of timely availability have raised interest in other testing modalities. The author notes that a recent meta-analysis of the use of portable monitors for home-based diagnosis concluded that the quality of most monitors was not high. Home oximetry monitoring alone had poor specificity in diagnosing sleep apnea (48 percent) compared with polysomnography. Monitors that included continuous nasal air pressure measurement showed improved specificity in recent small studies.
Treatment of sleep apnea is complicated by several issues. Although rates of hypertension and other cardiovascular diseases are known to be higher in patients with sleep apnea, no prospective trials show that treatment improves cardiovascular outcomes. The author notes that the primary reason to treat sleep apnea is to improve quality of life. The severity of disease quantified by testing does not correlate well with quality of life, although a respiratory disturbance index (home monitors) or apneahypopnea index (polysomnography) of more than 30 events per hour generally denotes severe disease that merits treatment.
Continuous positive airway pressure (CPAP) has been shown in randomized trials to immediately reverse sleep apnea, decrease somnolence, and improve quality of life. Compliance with CPAP is problematic, however. Patients may become frustrated by mask leaks or nasal congestion. The author describes conservative treatment that should be undertaken in all patients, including use of a lateral sleep position, avoidance of nighttime alcohol or sedatives, and weight loss.
Oral appliances that keep the jaw forward during sleep are sometimes used in the treatment of sleep apnea. A surgical procedure is also an alternative (e.g., uvulopalatopharyngoplasty, mandibular advancement), but there are fewer data from high-quality studies to demonstrate the effectiveness of surgery. The author suggests reserving surgery for patients intolerant of CPAP.