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Inhomogeneity of pulmonary perfusion during sustained microgravity on SLS-1We studied the effects of gravity on the inhomogeneity of pulmonary perfusion in humans by performing hyperventilation-breath-hold single-breath measurements before, during, and after 9 days of continuous exposure to microgravity during the Spacelab Life Sciences-1 (SLS-1) mission. In microgravity the indicators of inhomogeneity of perfusion, especially the size of cardiogenic oscillations in expired CO2 and the height of phase IV, were markedly reduced. Cardiogenic oscillations were reduced to approximately 60% of their preflight standing size, and the height of phase IV was between 0 and -8% (a terminal fall became a small terminal rise) of the preflight standing value. The terminal change in expired CO2 was nearly abolished in microgravity, indicating more uniformity of blood flow between lung units that close and those that remain open at the end of expiration. A possible explanation of this observation is the disappearance of gravity-dependent topographic inequality of blood flow. The residual cardiogenic oscillations in expired CO2 imply a persisting inhomogeneity of perfusion in the absence of gravity, probably in lung regions that are not within the same acinus.
Document ID
19950030354
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Prisk, G. Kim
(University of California, San Diego, La Jolla, CA United States)
Guy, Harold J. B.
(University of California, San Diego, La Jolla, CA United States)
Elliott, Ann R.
(University of California, San Diego, La Jolla, CA United States)
West, John B.
(University of California, San Diego, La Jolla, CA United States)
Date Acquired
August 16, 2013
Publication Date
April 1, 1994
Publication Information
Publication: Journal of Applied Physiology
Volume: 76
Issue: 4
ISSN: 8750-7587
Subject Category
Aerospace Medicine
Accession Number
95A61953
Funding Number(s)
CONTRACT_GRANT: NAS9-16037
Distribution Limits
Public
Copyright
Other

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