NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Cardiovascular Deconditioning and Venous Air Embolism in Simulated Microgravity in the RatAstronauts conducting extravehicular activities undergo decompression to a lower ambient pressure, potentially resulting in gas bubble formation within the tissues and venous circulation. Additionally, exposure to microgravity produces fluid shifts within the body leading to cardiovascular deconditioning. A lower incidence of decompression illness in actual spaceflight compared with that in ground-based altitude chamber flights suggests that there is a possible interaction between microgravity exposure and decompression illness. The purpose of this study was to evaluate the cardiovascular and pulmonary effects of simulated hypobaric decompression stress using a tail suspension (head-down tilt) model of microgravity to produce the fluid shifts associated with weightlessness in conscious, chronically instrumented rats. Venous bubble formation resulting from altitude decompression illness was simulated by a 3-h intravenous air infusion. Cardiovascular deconditioning was simulated by 96 h of head-down tilt. Heart rate, mean arterial blood pressure, central venous pressure, left ventricular wall thickening and cardiac output were continuously recorded. Lung studies were performed to evaluate edema formation and compliance measurement. Blood and pleural fluid were examined for changes in white cell counts and protein concentration. Our data demonstrated that in tail-suspended rats subjected to venous air infusions, there was a reduction in pulmonary edema formation and less of a decrease in cardiac output than occurred following venous air infusion alone. Mean arterial blood pressure and myocardial wall thickening fractions were unchanged with either tail-suspension or venous air infusion. Heart rate decreased in both conditions while systemic vascular resistance increased. These differences may be due in part to a change or redistribution of pulmonary blood flow or to a diminished cellular response to the microvascular insult of the venous air embolization.
Document ID
19980017618
Acquisition Source
Johnson Space Center
Document Type
Contractor Report (CR)
Authors
Robinson, R. R.
(Texas Univ. Health Science Center Houston, TX United States)
Doursout, M.-F.
(Texas Univ. Health Science Center Houston, TX United States)
Chelly, J. E.
(Texas Univ. Health Science Center Houston, TX United States)
Powell, M. R.
(Space Biomedical Research Inst. Houston, TX United States)
Little, T. M.
(Texas Univ. Health Science Center Houston, TX United States)
Butler,B. D.
(Texas Univ. Health Science Center Houston, TX United States)
Date Acquired
September 6, 2013
Publication Date
September 1, 1996
Publication Information
Publication: Aviation, Space and Environmental Medicine
Publisher: Aerospace Medical Association
Volume: 67
Issue: 9
Subject Category
Aerospace Medicine
Report/Patent Number
NASA/CR-96-207112
NAS 1.26:207112
Funding Number(s)
CONTRACT_GRANT: NAG9-215
CONTRACT_GRANT: NCC9-20
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
No Preview Available