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Cardiogenic oscillation phase relationships during single-breath tests performed in microgravityWe studied the phase relationships of the cardiogenic oscillations in the phase III portion of single-breath washouts (SBW) in normal gravity (1 G) and in sustained microgravity (microG). The SBW consisted of a vital capacity inspiration of 5% He-1.25% sulfurhexafluoride-balance O2, preceded at residual volume by a 150-ml Ar bolus. Pairs of gas signals, all of which still showed cardiogenic oscillations, were cross-correlated, and their phase difference was expressed as an angle. Phase relationships between inspired gases (e.g., He) and resident gas (n2) showed no change from 1 G (211 +/- 9 degrees) to microG (163 +/- 7 degrees). Ar bolus and He were unaltered between 1 G (173 +/- 15 degrees) and microG (211 +/- 25 degrees), showing that airway closure in microG remains in regions of high specific ventilation and suggesting that airway closure results from lung regions reaching low regional volume near residual volume. In contrast, CO2 reversed phase with He between 1 G (332 +/- 6 degrees) and microG (263 +/- 27 degrees), strongly suggesting that, in microG, areas of high ventilation are associated with high ventilation-perfusion ratio (VA/Q). This widening of the range of VA/Q in microG may explain previous measurements (G.K. Prisk, A.R. Elliott, H.J.B. Guy, J.M. Kosonen, and J.B. West J. Appl. Physiol. 79: 1290-1298, 1995) of an overall unaltered range of VA/Q in microG, despite more homogeneous distributions of both ventilation and perfusion.
Document ID
20040172774
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Lauzon, A. M.
(University of California San Diego La Jolla 92093, United States)
Elliott, A. R.
Paiva, M.
West, J. B.
Prisk, G. K.
Date Acquired
August 22, 2013
Publication Date
February 1, 1998
Publication Information
Publication: Journal of applied physiology (Bethesda, Md. : 1985)
Volume: 84
Issue: 2
ISSN: 8750-7587
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
manned
NASA Discipline Cardiopulmonary
short duration
Flight Experiment
STS-58 Shuttle Project

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