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Flow Redistribution Between Legs and Brain During STS 93 Re-Entry and LandingThe objective was to quantify bit by bit the arterial hemodynamic response to the successive acceleration induced fluid shifts during re-entry and landing. Method: The astronaut instrumented himself with a flat Doppler probe fixed on the skin, a blood pressure arm cuff, and 3 ECG electrodes. The ICMS (integrated cardiovascular monitoring system, 15x15x25 cu cm, battery powered) designed to monitor Blood pressure, ECG, cerebral and femoral flows was fixed below the astronaut sit in the middeck. Recordings started 5 minutes before de-orbiting (TIG) and stopped 5 min after wheels stop. Results. During re-entry blood pressure increased by 20% at TIG, and then by 25 to 30% during the highest Gz accelerations (approx 1 S g ) . The cerebral flow remained decreased by 10 to 15% below inflight value all during the Entry and landing phases. Conversely the femoral flow increased at TIG and entry ( + l0 to 20%), recovered at 0.lg, and then decreased in proportion with the Gz acceleration (-10% to -40% from 0.5g to 1.5g). The reduction in Femoral flow was associated with an opposite variation in lower limb vascular resistance. Consequently the cerebral flow/femoral flow ratio decreased at TIG and entry (-20%), and then increased according to the Gz acceleration level ( + l0 to +40% from 0.5 to 1.5g). Conclusion: During orthostatic tests (Stand LBNP tests) the cerebral to femoral flow ratio allowed to quantify the efficiency of the flow redistribution between these 2 areas and predicted orthostatic intolerance. In the present case the astronaut was found orthostatically tolerant at postflight tilt tests, but we suggest that during re-entry this parameter could predict the occurrence of syncope in severely disadapted astronauts.
Document ID
20040070927
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Arbeille, P.
(Hopital Bretonneau Tours, France)
Meck, J.
(Wyle Labs., Inc. Houston, TX, United States)
Porcher, M.
(Hopital Bretonneau Tours, France)
Benavides, E.
(Wyle Labs., Inc. Houston, TX, United States)
Martin, D. S.
(Wyle Labs., Inc. Houston, TX, United States)
South, D. A.
(Wyle Labs., Inc. Houston, TX, United States)
Ribeiro, C.
(Wyle Labs., Inc. Houston, TX, United States)
Westover, A.
(Wyle Labs., Inc. Houston, TX, United States)
Date Acquired
August 21, 2013
Publication Date
July 1, 2003
Publication Information
Publication: Journal of Gravitational Physiology
Publisher: Galileo Foundation
Volume: 10
Issue: 1
ISSN: 1077-9248
Subject Category
Aerospace Medicine
Meeting Information
Meeting: 24th Annual Gravitational Physiology Meeting
Location: Santa Monica, CA
Country: United States
Start Date: May 4, 2003
End Date: May 9, 2003
Sponsors: International Society for Gravitational Physiology
Funding Number(s)
CONTRACT_GRANT: NAG2-6072
Distribution Limits
Public
Copyright
Other

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