Lower leg fluid displacement during a simulated space shuttle launch.
Reductions in leg fluid volume of about 1/per leg or 10% of total leg volume have been reported during space flight. We wanted to test the hypothesis that a significant portion of these changes occur during the prelaunch and launch periods. Fluid volume changes in the lower leg were estimated in six men during a simulated Space Shuttle launch. After 2 h in the launch position, i.e. supine with elevated legs, the subjects were exposed to 500 s of two to three times increased g force in the anterio-posterior direction in a human centrifuge. During the prelaunch period one lower leg lost a mean of (113 SD 53) ml of fluid and there was little or no additional fluid reduction during the period of increased g force. This compares with the 178-ml reduction of lower leg volume that has been reported during the 1st day of Shuttle missions. We concluded that a significant portion of the fluid reduction observed in the lower leg during the early stages of space flight had already occurred before the launch.
Linnarsson
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Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Tedner
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Lindborg
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B
D000328:Adult; D001794:Blood Pressure; D001826:Body Fluids / Q000502:physiology*; D002498:Centrifugation; D004562:Electrocardiography; D006339:Heart Rate; D006801:Humans; D007866:Leg; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011187:Posture; D013026:Space Flight; D014893:Weightlessness