Progressive changes in airway resistance during sleep.
Kay, Amanda, John Trinder, and Young Kim.
School of Behavioural Science, University of Melbourne, Melbourne,
Australia
APStracts 3:0101A, 1996.
Ventilation () decreases during sleep while upper airway resistance
(UAR) increases. A number of studies has suggested that in normal
healthy individuals the changes in the two variables are reciprocal.
Other findings, however, suggest that the relationship between and
UAR may change as NREM sleep progresses, such that most of the change
in occurs early during the sleep period whereas the most marked
changes in UAR occur later during established NREM sleep. However, no
study has examined the progressive development of changes in both and
UAR over the NREM sleep period. This study examined and UAR over one
NREM sleep period in two groups of healthy young male subjects: a
"SWS group" (n=8) in which the subjects obtained the full
range of NREM sleep stages from W to stage 4 NREM; and a "no-SWS
group" (n=5) in which subjects did not attain SWS but spent a
prolonged period in stage 2 NREM that was repeatedly interrupted by
arousals. Results showed that the most marked changes in occurred
early during the sleep period in association with relatively small
increases in UAR. Once NREM sleep became established, further
attenuation of was minimal despite marked and progressive increases
in UAR. The progressive increase in UAR occurred in association with
increasing delta (0.4-3.0 Hz) EEG activity and did not occur in the
no-SWS group. We interpret these findings to indicate that factors in
addition to UAR contribute to the reduction in early in sleep onset,
while later during NREM sleep compensatory mechanisms are activated
to allow for maintenance of in the context of larger increases in
UAR.
Received 7 August 1995; accepted in final form 25 January 1996.
APS Manuscript Number A862-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 14 February 96