Obstructive sleep apnea
For many years clinicians viewed sleep with detached interest. Perhaps sleep was regarded as a secure harbor in which the weary patient could seek refuge, later emerging refreshed to confront the trials of the next day’s voyage. This assumption was facilitated because physicians had not been able to examine the harbor, which now has been shown to change rapidly, at times becoming turbulent and exerting demands of its own.
A night of sleep consists of repeated cycling between rapid eye movement (REM) and non-REM sleep. Mechanisms governing vital body functions are surprisingly different in these states, such that we are forced to shift physiologic gears frequently each night.1 Some individuals have serious problems in one or both sleep states despite seemingly good health during wakefulness.
Another serious misconception has prevailed from the time of Burwell’s description of the Pick-wickian syndrome.2 Sleep-induced ventilatory failure often has been thought of as a relatively uncommon problem, associated for the most part with morbid obesity. Therapeutic efforts frequently have concentrated on altered pulmonary mechanics, ventilation-perfusion mismatch, impaired ventilatory drive, and the various cardiovascular and throm-boembolic complications of this readily diagnosed entity.
In contrast, the past decade has revealed that sleep apnea is not rare, and that only a minority of those afflicted are morbidly obese. Finally, upper airway obstruction during sleep has emerged as the greatest single factor in most cases of sleep-induced ventilatory failure.Definitions
An episode of sleep apnea denotes cessation of airflow at the mouth and nose for 10 seconds or . . .