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Blood volume reduction counteracts fluid shifts in water immersionSix healthy men were bled by 15 percent of their total blood volume (TBV) before 7 h of seated water immersion, to test the hypothesis that some of the major physiological responses to an expansion of central blood volume can be counteracted by prior reduction of TBV. Subjects were their own controls under two conditions: seated dry in air and seated immersed to the suprasternal notch in water. Immersion without prior reduction of TBV Wet Control (WC) caused a statistically significant 22-percent increase in cardiac output (CO), 368-percent increase in urine production, and 200-percent increase in sodium excretion relative to dry control (DC) sessions. When TBV was reduced before immersion, CO was the same as during DC sessions; however there were significant increases above DC in urine flow (+73 percent) and sodium excretion (+120 percent), although they were significantly reduced from WC values. Potassium excretion was similar during DC and WC sessions, but was significantly increased (+75 percent) when subjects were immersed after 15-percent reduction of TBV.
Document ID
19930041209
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Simanonok, Karl E.
(NASA Lyndon B. Johnson Space Center Houston, TX, United States)
Bernauer, Edmund
(California Univ. Davis, United States)
Date Acquired
August 16, 2013
Publication Date
February 1, 1993
Publication Information
Publication: Aviation, Space, and Environmental Medicine
Volume: 64
Issue: 2
ISSN: 0095-6562
Subject Category
Aerospace Medicine
Accession Number
93A25206
Funding Number(s)
CONTRACT_GRANT: NGT-05-004-801
Distribution Limits
Public
Copyright
Other

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