NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
cardiovascular response to lower body negative pressure stimulation before, during, and after space flightBACKGROUND: It is well known that space travel cause post-flight orthostatic hypotension and it was assumed that autonomic cardiovascular control deteriorates in space. Lower body negative pressure (LBNP) was used to assess autonomic function of the cardiovascular system. METHODS: LBNP tests were performed on six crew-members before and on the first days post-flight in a series of three space missions. Additionally, two of the subjects performed LBNP tests in-flight. LBNP mimics fluid distribution of upright posture in a gravity independent way. It causes an artificial sequestration of blood, reduces preload, and filtrates plasma into the lower part of the body. Fluid distribution was assessed by bioelectrical impedance and anthropometric measurements. RESULTS: Heart rate, blood pressure, and total peripheral resistance increased significantly during LBNP experiments in-flight. The decrease in stroke volume, the increased pooling of blood, and the increased filtration of plasma into the lower limbs during LBNP indicated that a plasma volume reduction and a deficit of the interstitial volume of lower limbs rather than a change in cardiovascular control was responsible for the in-flight response. Post-flight LBNP showed no signs of cardiovascular deterioration. The still more pronounced haemodynamic changes during LBNP reflected the expected behaviour of cardiovascular control faced with less intravascular volume. In-flight, the status of an intra-and extravascular fluid deficit increases sympathetic activity, the release of vasoactive substances and consequently blood pressure. Post-flight, blood pressure decreases significantly below pre-flight values after restoration of volume deficits. CONCLUSION: We conclude that the cardiovascular changes in-flight are a consequence of a fluid deficit rather than a consequence of changes in autonomic signal processing.
Document ID
20040112653
Document Type
Reprint (Version printed in journal)
Authors
Baisch, F.
(Deutsches Zentrum fur Luft- und Raumfahrt, Cologne, Germany)
Beck, L.
Blomqvist, G.
Wolfram, G.
Drescher, J.
Rome, J. L.
Drummer, C.
Date Acquired
August 21, 2013
Publication Date
December 1, 2000
Publication Information
Publication: European journal of clinical investigation
Volume: 30
Issue: 12
ISSN: 0014-2972
Subject Category
Aerospace Medicine
Distribution Limits
Public
Copyright
Other
Keywords
manned
NASA Discipline Cardiopulmonary
Non-NASA Center
Soyuz TM14 Project
Flight Experiment
Soyuz TM25 Project
long duration
short duration
NASA Experiment Number 284080 1/2
STS-55 Shuttle Project