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Lung volumes during sustained microgravity on Spacelab SLS-1Gravity is known to influence the mechanical behavior of the lung and chest wall. However, the effect of sustained microgravity (microgravity) on lung volumes has not been reported. Pulmonary function tests were performed by four subjects before, during, and after 9 days of microgravity exposure. Ground measurements were made in standing and supine postures. Tests were performed using a bag-in-box-and-flowmeter system and a respiratory mass spectrometer. Measurements included functional residual capacity (FRC), expiratory reserve volume (ERV), residual volume (RV), inspiratory and expiratory vital capacities (IVC and EVC), and tidal volume (V9sub T)). Total lung capacity (TLC) was derived from the measured EVC and RV values. With preflight standing values as a comparison, FRC was significantly reduced by 15% (approximately 500 ml) in microgravity and 32% in the supine posture. ERV was reduced by 10 - 20% in microgravity and decreased by 64% in the supine posture. RV was significantly reduced by 18% (310 ml) in microgravity but did not significantly change in the supine posture compared with standing. IVC and EVC were slightly reduced during the first 24 h of microgravity but returned to 1-G standing values within 72 h of microgravity exposure. IVC and EVC in the supine posture were significantly reduced by 12% compared with standing. During microgravity, V(sub T) decreased by 15% (approximately 90 ml), but supine V(sub T) was unchanged compared with preflight standing values. TLC decreased by approximately 8% during microgravity and in the supine posture compared with preflight standing. The reductions in FRC, ERV, and RV during microgravity are probably due to the cranial shift of the diaphragm, an increase in intrathoracic blood volume, and more uniform alveolar expansion.
Document ID
19950042778
Document Type
Reprint (Version printed in journal)
Authors
Elliott, Ann R. (California Univ. San Diego, La Jolla, CA, United States)
Prisk, G. Kim (California Univ. San Diego, La Jolla, CA, United States)
Guy, Harold J. B. (California Univ. San Diego, La Jolla, CA, United States)
West, John B. (California Univ. San Diego, La Jolla, CA, United States)
Date Acquired
August 16, 2013
Publication Date
October 1, 1994
Publication Information
Publication: Journal of Applied Physiology
Volume: 77
Issue: 4
ISSN: 8750-7587
Subject Category
AEROSPACE MEDICINE
Funding Number(s)
CONTRACT_GRANT: NAS9-16037
Distribution Limits
Public
Copyright
Other