EFFECT OF INDUCED TRANSIENT AROUSAL ON OBSTRUCTIVE APNEA DURATION

Six untreated male patients (age 19-55 yr) with obstructive sleep apne a underwent nocturnal polysomnography with acoustic stimulation to det ermine the effect of transient arousal on obstructive apneas during sl eep. Binaural tone bursts (25-95 dB) were delivered in late expiration during the second obstructive apnea of a cycle consisting of four con secutive apneas. For the group, stimulated apneas were significantly s horter (P < 0.05, Fisher's protected least significant difference test ) than were the unstimulated apneas when transient electrocortical aro usal was elicited in both non-rapid-eye-movement (non-REM) sleep [mean 17 +/- 7 (SD) vs. 26 +/- 9, 23 +/- 10, and 26 +/- 12 s for 2nd vs. 1s t, 3rd, and 4th apnea, respectively, of each cycle] and REM sleep (mea n 19 +/- 10 vs. 35 +/- 15, 45 +/- 18, and 39 +/- 20 s). Without electr ocortical arousal, the stimulated apnea was significantly shortened in non-REM (23 +/- 9 vs. 25 +/- 7, 24 +/- 8, and 26 +/- 8 s) but not in REM (32 +/- 16 vs. 37 +/- 12, 32 +/- 15, and 30 +/- 16 s). Tones deliv ered relatively early and late in the apnea were equally likely to be associated with resolution of the apnea. The nadir of arterial oxygen saturation of hemoglobin was inversely proportional to apnea length, w ith higher saturation nadirs associated with the stimulated apneas. Th ese data indicate that transient arousal, induced by nonrespiratory st imulation, influences the resolution of obstructive apneas during slee p.