Effects of upper airway stimulation on swallowing, gasping and
autoresuscitation in hypoxic mice.
Thach, Atul Khurana Bradley T.
Edward Mallinckrodt Department of Pediatrics, Washington University
School of Medicine, St. Louis Missouri, 63110
APStracts 2:0405A, 1995.
Severe hypoxia produces a state of neural depression known as hypoxic
coma in which reflex activity is believed to be absent but from which
spontaneous recovery ("autoresuscitation") still can occur.
We evaluated the swallowing reflex during hypoxic coma employing
mechanical and chemosensory stimuli. Balb-C mice were given 97% N2 -
3% CO2 to breathe. At onset of coma, a 0.05 cc bolus of saline or
water was infused into the pharynx. Unlike mechanical stimulation
(sham infusion) fluid infusion usually was followed by rapid
swallowing, more so with water than saline. This model allowed
examination of interactions between swallowing, hypoxic gasping,
airway fluid removal and autoresuscitation. Compared to sham
infusion, saline and water reduced gasping rate equally. Saline,
however, prolonged the process of autoresuscitation more than water,
an effect possibly related to an observed increased retention of
saline in the airway. Occasionally mice failed to swallow following
infusions, in which case airway obstruction during gasping and
autoresuscitation failure was repeatedly observed. These studies
suggest that the swallowing component of the laryngeal chemoreflex is
present during hypoxic coma and that swallowing facilitates
autoresuscitation when upper airway fluid is present.
Received 1 April 1994; accepted in final form 11 September 1995.
APS Manuscript Number A311-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 31 October 95