INFLUENCE OF SLEEP ON RESPONSE TO NEGATIVE AIRWAY PRESSURE OF TENSOR-PALATINI MUSCLE AND RETROPALATAL AIRWAY

Increased retropalatal airway resistance may be caused by a sleep-indu ced loss of palatal muscle activity and a diminished ability of these muscles to respond to the increasing intrapharyngeal negative pressure that develops during sleep. To investigate these possibilities, in si x normal subjects, we determined the effect of non-rapid-eye-movement sleep on 1) the tensor palatini (TP) electromyogram (EMG) response to rapid-onset negative-pressure generations (NPG) in the upper airway an d 2) the collapsibility of the retropalatal airway during these NPGs. During wakefulness, the change in TP EMG from basal to peak levels (du ring NPG) was 19.8 +/- 3.2 arbitrary units (P < 0.005). This was marke dly reduced during sleep (3.6 +/- 1.5 arbitrary units; P < 0.001). The latency of the TP EMG response was 48.5 +/- 5.6 ms during wakefulness but was prolonged during sleep (105.0 +/- 12.2 ms; P < 0.02). The pea k transpalatal pressure during NPG (a measure of airway collapse) was 2.1 +/- 0.7 cmH2O during wakefulness and increased to 5.3 +/- 0.8 cmH2 O during sleep (P < 0.05). We conclude that the brisk reflex response of the TP muscle to negative pressure during wakefulness is markedly r educed during non-rapid-eye-movement sleep, in association with a more collapsible retropalatal airway. We speculate that the reduction in t his TP reflex response contributes to retropalatal airway narrowing du ring sleep in normal subjects.