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Skin cooling maintains cerebral blood flow velocity and orthostatic tolerance during tilting in heated humansOrthostatic tolerance is reduced in the heat-stressed human. The purpose of this project was to identify whether skin-surface cooling improves orthostatic tolerance. Nine subjects were exposed to 10 min of 60 degrees head-up tilting in each of four conditions: normothermia (NT-tilt), heat stress (HT-tilt), normothermia plus skin-surface cooling 1 min before and throughout tilting (NT-tilt(cool)), and heat stress plus skin-surface cooling 1 min before and throughout tilting (HT-tilt(cool)). Heating and cooling were accomplished by perfusing 46 and 15 degrees C water, respectively, though a tube-lined suit worn by each subject. During HT-tilt, four of nine subjects developed presyncopal symptoms resulting in the termination of the tilt test. In contrast, no subject experienced presyncopal symptoms during NT-tilt, NT-tilt(cool), or HT-tilt(cool). During the HT-tilt procedure, mean arterial blood pressure (MAP) and cerebral blood flow velocity (CBFV) decreased. However, during HT-tilt(cool), MAP, total peripheral resistance, and CBFV were significantly greater relative to HT-tilt (all P < 0.01). No differences were observed in calculated cerebral vascular resistance between the four conditions. These data suggest that skin-surface cooling prevents the fall in CBFV during upright tilting and improves orthostatic tolerance, presumably via maintenance of MAP. Hence, skin-surface cooling may be a potent countermeasure to protect against orthostatic intolerance observed in heat-stressed humans.
Document ID
20040088269
Document Type
Reprint (Version printed in journal)
Authors
Wilson, Thad E.
(Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas Texas 75321, United States)
Cui, Jian
Zhang, Rong
Witkowski, Sarah
Crandall, Craig G.
Date Acquired
August 21, 2013
Publication Date
July 1, 2002
Publication Information
Publication: Journal of applied physiology (Bethesda, Md. : 1985)
Volume: 93
Issue: 1
ISSN: 8750-7587
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: HL-67422
CONTRACT_GRANT: HL-10488
CONTRACT_GRANT: HL-61388
Distribution Limits
Public
Copyright
Other
Keywords
Clinical Trial
Non-NASA Center
NASA Discipline Cardiopulmonary
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