Obstructive sleep apnea: a clinical review

BACKGROUND Since the original classification of the obstructive nature of obstructive sleep apnea syndrome (OSAS) in 1965, much has been learned about the disorder. In 1990 respiratory disturbances during sleep have come to be recognized as extremely common disorders with important clinical consequences.
DISCUSSION It is a condition with high prevalence of obesity as a major risk factor. Premenopausal women are relatively protected from the disorder: its prevalence in women rises after menopause. Although OSAS is a risk factor for excessive daytime sleepiness, there is developing evidence that it is also a risk factor for hypertension, acute cardiovascular events, and insulin resistance. Definitive diagnosis still depends on in-laboratory polysomnography. This involves recording of multiple variables during sleep, including electroencephalogram. There is a considerable interest in the role of unattended home sleep-monitoring and some evidence of its usefulness has yet to be established. The first line of therapy is nasal continuous positive airway pressure (CPAP). Data into the efficacy of CPAP in severe OSAS have come from randomized, placebo-controlled clinical trials the endpoints of which being sleepiness, quality of life, and 24-h ambulatory blood pressure. Data are currently less convincing for treatment outcomes in mild to moderate OSAS, and new clinical trails to assess outcomes in this group are underway.
CONCLUSION The field of sleep medicine has now firmly entered the mainstream of clinical practice, substantial progress has been made, and OSAS has increasingly emerged as a major public health concern. The Internal Medicine specialist has to recognize this clinical entity.