Document Detail

Effect of 6 degrees head-down tilt on cardiopulmonary function: comparison with microgravity.
MedLine Citation:
PMID:  11817623     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Head-down tilt (HDT) of 6 degrees is a commonly used model of weightlessness, but there are few comparisons with actual microgravity. HYPOTHESIS: Our study was designed to prove that the changes in cardiopulmonary function seen in HDT would be similar to those seen in microgravity. METHODS: We compared measurements of cardiovascular and pulmonary function from three separate spaceflights of 14 to 17 d duration, with data collected during a 17-d period of HDT. RESULTS: HDT proved a good model of the cardiovascular response to microgravity, resulting in increases in cardiac output and stroke volume of a similar magnitude to those seen in microgravity, with a concomitant reduction in heart rate. By contrast, HDT was a poor model of the effects of microgravity on pulmonary ventilation and gas exchange. CONCLUSION: Pulmonary function in HDT approximated the changes seen in the 1-G supine posture, while in microgravity this was much closer to that seen in the 1-G upright position. The differences probably reflect the fact that changes in cardiovascular function result primarily from fluid shifts within the entire body, whereas changes in pulmonary ventilation are primarily a result of mechanical influences on the lung and chest and abdominal wall.
G Kim Prisk; Janelle M Fine; Ann R Elliott; John B West
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  73     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  2002 Jan 
Date Detail:
Created Date:  2002-01-30     Completed Date:  2002-05-10     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7501714     Medline TA:  Aviat Space Environ Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  8-16     Citation Subset:  IM; S    
Department of Medicine, University of California, San Diego, La Jolla, 92093-0931, USA.
Space Flight Mission:
Flight Experiment; STS-58 Shuttle Project; STS-78 Shuttle Project; STS-90 Shuttle Project; manned; short duration
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MeSH Terms
Cardiac Output
Head-Down Tilt*
Heart / physiology*
Lung / physiology*
Middle Aged
Pulmonary Gas Exchange
Respiratory Function Tests
Weightlessness Simulation*
Grant Support
G K Prisk / U CA San Diego, La Jolla; J B West / U CA San Diego, La Jolla

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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