Effects of slow wave sleep on ventilatory compensation to inspiratory elastic loading

Abstract

We determined the effects of slow wave sleep on ventilatory conpensation to inspiratory elastic loads 918 cm H 2O/L). Multiple loading trials of variable duration were applied in three healthy adult humans in wakefulness and during NREM sleep. During wakefulness, ventilatory response over 5 loaded breaths were highly variable. Tidal volume (V T), mean inspiratory flow (V t/T i), and minute ventilation (V̇ e) were preserved or increased in 2 of the 3 subjects in whom mouth occlusion pressure (P 0.1) was augmented in the immediated (second breath) response to the load. In ther third subjects who showed no changed in P 0.1, V̇ e was not preserved during loading. During NREM sleep, the loading response was highly consistent in all trials and in all 3 subjects P 0.1 on the second loaded breath was not increased; thus V̇ t and V t/T i were reduced over five loaded breaths. This absence of immediate loaded conpensation during NREM sleep was similar during normoxia, hyperoxia, and hypercapnia. During sustained loading in NREM sleep V̇ t and V t returned toward control levels coincident with an increase in end tidal CO 2 We conclude that augmentation of respiratory neural drive sufficient for immediate compensation to elastic loads requires wakefulness. Compensatory responses to loading do not occur during NREM sleep until inmpiratory effort is augmented by chemical stimuli.