Breathing during wakefulness and nrem sleep in humans without an
upper airway.
Morrell, M. J., H. R. Harty, L. Adams, and A. Guz.
Department of Medicine, Charing Cross and Westminster Medical
School, London, W6 8RF UK
APStracts 3:0093A, 1996.
The increase in PCO2 which occurs during sleep may reflect an
inadequate ventilatory compensation to an increase in upper airway
resistance. To address this question in humans, we examined changes
in breathing during wakefulness and Non-Rapid Eye Movement (NREM)
sleep in 8 laryngectomized subjects who breathed through a tracheal
stoma. In these subjects any sleep-related increase in upper airway
resistance could not affect ventilation. Healthy subjects breathing
via an intact upper airway were studied as controls. The mean (+/-sd)
increase in end-tidal PCO2 from wakefulness to sleep was 2.7 (+/-2.6;
p = 0.05) mmHg in laryngectomees and 1.6 (+/-1.4; p = 0.02) mmHg in
controls. During wakefulness, ventilation was lower in laryngectomees
compared with controls, although this difference was not
statistically significant (6.8 (+/-1.9) l/min vs. 7.4 (+/-1.2) l/min;
p > 0.05). During sleep, the fall in ventilation was similar in
the two groups (1.1 (+/-2.1) l/min vs. 0.8 (+/-2.1) l/min; p >
0.05). Our observations are not consistent with the view that
increases in upper airway resistance are obligatory for sleep-related
CO2 retention in humans.
Received 16 March 1995; accepted in final form 6 February 1996.
APS Manuscript Number A287-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 14 February 96