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Enhancement of preoxygenation for decompression sickness protection: effect of exercise durationINTRODUCTION: Since strenuous exercise for 10 min during preoxygenation was shown to provide better protection from decompression sickness (DCS) incidence than resting preoxygenation, a logical question was: would a longer period of strenuous exercise improve protection even further? HYPOTHESIS: Increased strenuous exercise duration during preoxygenation increases DCS protection. METHODS: There were 60 subjects, 30 men and 30 women, who were exposed to 9,144 m (4.3 psia) for 4 h while performing mild, upper body exercise. Before the exposures, each subject performed three preoxygenation profiles on different days in balanced order: a 90-min resting preoxygenation control; a 240-min resting preoxygenation control; and a 90-min preoxygenation including exercise during the first 15 min. The subjects were monitored at altitude for venous gas emboli (VGE) with an echo-imaging system and observed for signs and symptoms of DCS. RESULTS: There were no significant differences in occurrence of DCS following any of the three preoxygenation procedures. Results were also comparable to an earlier report of 42% DCS with a 60-min preoxygenation including a 10-min exercise. There was no difference between VGE incidence in the comparison of protection offered by a 90-min preoxygenation with or without 13 min of strenuous exercise. The DCS incidence following a 240-min resting preoxygenation, 40%, was higher than observed during NASA studies and nearly identical with the earlier 42% DCS after a 60-min preoxygenation including exercise during the first 10 min. CONCLUSION: The protection offered by a 10 min exercise in a 60-min preoxygenation was not increased with extension of the preoxygenation exercise period to 15 min in a 90-min preoxygenation, indicating an upper time limit to the beneficial effects of strenuous exercise.
Document ID
20040087921
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Webb, James T.
(Air Force Research Laboratory, [Wyle Laboratories, Systems Life Sciences, and Services] Brooks AFB, San Antonio, TX 78232, United States)
Pilmanis, Andrew A.
Fischer, Michele D.
Kannan, Nandini
Date Acquired
August 21, 2013
Publication Date
December 1, 2002
Publication Information
Publication: Aviation, space, and environmental medicine
Volume: 73
Issue: 12
ISSN: 0095-6562
Subject Category
Aerospace Medicine
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Environmental Health
Clinical Trial
Non-NASA Center
Controlled Clinical Trial

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