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Venous compliance and fluid shift measurements on Spacelab IML-1During the first few hours of a human spaceflight mission, a headward fluid shift out of the abdomen, pelvis, and legs initiates a number of adaptive cardiovascular responses, including a loss of intravascular and extravascular fluid volume. On return to earth, these cardiovascular changes may lead to debilitating symptoms of orthostatic intolerance in an unprotected astronaut. To test the hypothesis that an inflight increase in compliance of the leg veins may contribute to this condition, measurements of lower leg fluid shift and bulk venous compliance were collected from crew members during the eight-day First International Microgravity Laboratory shuttle mission. An ultrasonic limb plethysmograph, in conjunction with two compression cuffs encircling the calf and thigh, was used to determine bulk compliance of the underlying veins over a range of negative and positive transmural pressures. The data from inflight experiment sessions were compared to preflight and postflight sessions. The preliminary results indicate that the volume of the lower leg decreased by over 10 percent by the sixth day of flight, but there was no apparent change in venous compliance.
Document ID
19940030780
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Leiski, D.
(Canadian Space Agency Ottawa, Ontario., Canada)
Thirsk, R. B.
(Canadian Space Agency Ottawa, Ontario., Canada)
Charles, J. B.
(NASA Lyndon B. Johnson Space Center Houston, TX, United States)
Bennett, B.
(NASA Lyndon B. Johnson Space Center Houston, TX, United States)
Date Acquired
August 16, 2013
Publication Date
November 1, 1992
Publication Information
Publication: Canadian Aeronautics and Space Inst., Proceedings of the Seventh Conference on Astronautics
Subject Category
Aerospace Medicine
Accession Number
94N35286
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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