Individual differences in the relationship between upper airway
resistance and ventilation during sleep onset.
Kay, Amanda, John Trinder, and Young Kim.
School of Behavioural Science, University of Melbourne, Melbourne,
Australia.
APStracts 2:0141A, 1995.
Sleep-induced hypoventilation is caused partly by inadequate
compensation for elevated upper airway resistance (UAR). Some
evidence suggests that the effect of UAR on ventilation may vary
between individuals. The relationship between minute ventilation (V)
and UAR was examined in 26 healthy young males (average of 10.12
sleep onsets). Variables were analysed over transitions between
wakefulness (defined by alpha EEG activity) and sleep (theta EEG
activity). Transitions to sleep were associated with increases in UAR
in synchrony with reductions in V, and equally rapid, opposite
changes occurred with awakenings. The relationship between magnitudes
of the changes in V and UAR at transitions varied between subjects,
accounting for 30% of the variance for alpha to theta transitions and
50% of the variance for theta to alpha transitions. Results indicated
that although ventilatory changes during sleep onset are partly a
consequence of changes in UAR, alterations in UAR do not account
fully for alterations in ventilation. Other factors which may
contribute to ventilatory instability during sleep onset include
state-related fluctuations in drive to the primary respiratory
muscles and variability in compensatory mechanisms.
Received 6 September 1994; accepted in final form 20 March 1995.
APS Manuscript Number A933-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 April 1995.