Influence of apnea type and sleep stage on nocturnal postapneic desaturation

Sleep apneas are periods of interrupted breathing during sleep. They may be due to upper or lower airway obstruction, abnormal central nervous system control, or a combination of both. Sleep apneas can reduce the oxygen concentration of the blood sufficiently to contribute to pulmonary hypertension and right-sided heart failure. In a study of 32 patients with sleep apnea, researchers determined which aspects of apnea had the greatest influence on the oxygen concentration of the blood. They found that obstructive apneas produced greater desaturation of oxygen than central apneas. Furthermore, the investigators found that the stage of sleep played a significant role in the consequences of apnea. Desaturation which occurred during obstructive apnea was greater in REM sleep than non-REM sleep. (REM, of course, stands for Rapid Eye Movement sleep, a state in which the brain displays an almost waking form of activity.) In some cases, outflow of air can continue to occur during the apneic episode. These instances of expiratory obstructive apnea were also associated with a great reduction in oxygen saturation, regardless of whether the apnea occurred during REM or non-REM sleep. (Consumer Summary produced by Reliance Medical Information, Inc.)