Effect of topical upper airway anesthesia on apnea duration across
the night in obstructive sleep apnea.
Cala, S. J., P. Sliwinski, M. G. Cosio, and R. J. Kimoff.
Royal Victoria Hospital, Desmond N. Stoker Sleep Laboratory, McGill
University, Montreal, Quebec, Canada, Medical Research Scholar of the
Fonds de la Recherche en Sant[acute]e du Qu[acute]ebec
APStracts 3:0409A, 1996.
We have previously reported that the duration of obstructive apneas
increases from the beginning to the end of the night (7). The aim of
this study was to test the hypothesis that stimulation of upper
airway (UA) sensory receptors during obstructed inspiratory efforts
contributes to arousal and apnea termination, and that a progressive
attenuation of this mechanism across the night contributes to apnea
lengthening. We studied seven patients (6 M, 1F) with severe OSA
(apnea-hyponea index = 93 +/- 26 events/hr) during two consecutive
nights of polysomnographic monitoring. On one night (random order) we
performed topical UA anesthesia with 0.2% tetracaine and on the
control night, sham anesthesia. We measured apnea duration,
esophageal pressure (Pes) during apneas, and apneic O2 desaturation.
Consistent with previous findings, apnea duration, number of
efforts/apnea, and peak Pes at end-apnea increased from the beginning
to the end of the control nights. UA anesthesia produced a
significant increase in apnea duration at the beginning of the night,
but no change in apnea length at the end of the night. Peak Pes and
the rate of increase in Pes during the anesthesia nights were greater
than during control nights, but the rate of increase in Pes was
similar for the beginning and end of the control and anesthesia
nights. These findings suggest that UA sensory receptors play a role
in mediating apnea termination at the beginning of the night, but
that the contribution of these receptors diminishes as the night
progresses such that greater inspiratory efforts are required to
trigger arousal, leading to apnea prolongation.
Received 10 January 1996; accepted in final form 15 August 1996.
APS Manuscript Number A24-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 September 1996