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Changes in leg volume during microgravity simulationLittle published information exists regarding the magnitude and time course of cephalad fluid shift resulting from microgravity simulations. Six subjects were exposed to 150 min each at horizontal bed rest, 6-deg head-down tilt, and horizontal water immersion. Fluid shift was estimated by calculating leg volumes from eight serial girth measurements from groin to ankle before, during, and after exposure. Results were compared with data from the first 3 h of spacecraft. By the end of exposure, total leg volume for the six subjects decreased by 2.6 +/- 0.8 percent, 1.7 +/- 1.2 percent, and 4.0 +/- 1.6 percent for horizontal, head-down, and immersion, respectively. Changes had plateaued for horizontal and head-down and had slowed for immersion. Relatively more fluid was lost from the lower leg than the thigh for all three conditions, particularly head-down. During the first 3 h of spaceflight, total leg volume decreased by 8.6 percent, and relatively more fluid was lost from the thigh than the lower leg. The difference in volume changes in microgravity and simulated microgravity may be caused by the small transverse pressures still present in ground-based simulations and the extremely nonlinear compliance of tissue.
Document ID
19920072105
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Thornton, William E.
(NASA Johnson Space Center Houston, TX, United States)
Hedge, Vickie
(NASA Lyndon B. Johnson Space Center Houston, TX, United States)
Coleman, Eugene
(Houston, University TX, United States)
Uri, John J.
(GE Government Services Houston, TX, United States)
Moore, Thomas P.
(Minnesota, University Minneapolis, United States)
Date Acquired
August 15, 2013
Publication Date
September 1, 1992
Publication Information
Publication: Aviation, Space, and Environmental Medicine
Volume: 63
Issue: 9, Se
ISSN: 0095-6562
Subject Category
Aerospace Medicine
Accession Number
92A54729
Distribution Limits
Public
Copyright
Other

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