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Lung volumes during sustained microgravity on Spacelab SLS-1
A R Elliott1, G K Prisk, H J Guy
1Department of Medicine, University of California, San Diego, La Jolla 92093-0931.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|October 1, 1994
Summary
Sustained microgravity significantly reduces lung volumes, including functional residual capacity and expiratory reserve volume, due to diaphragm changes and increased blood volume. These lung volume changes in microgravity impact respiratory mechanics.
Area of Science:
- Physiology
- Space Medicine
- Respiratory System
Background:
- Gravity significantly influences lung and chest wall mechanics.
- The effects of sustained microgravity on lung volumes remain largely unreported.
- Understanding these changes is crucial for astronaut health during spaceflight.
Purpose of the Study:
- To investigate the impact of sustained microgravity on various lung volumes.
- To compare microgravity lung volumes with ground-based measurements in standing and supine postures.
Main Methods:
- Pulmonary function tests were conducted on four subjects before, during, and after a 9-day microgravity exposure.
- Measurements included functional residual capacity (FRC), expiratory reserve volume (ERV), residual volume (RV), vital capacities (IVC, EVC), and tidal volume (VT).
- Total lung capacity (TLC) was derived, and comparisons were made with standing and supine ground measurements.
Main Results:
- Microgravity led to significant reductions in FRC (15%), ERV (10-20%), and RV (18%) compared to preflight standing values.
- Tidal volume (VT) decreased by 15% in microgravity, and total lung capacity (TLC) reduced by approximately 8%.
- Supine posture on the ground showed greater reductions in FRC (32%) and ERV (64%) than microgravity.
Conclusions:
- Sustained microgravity alters lung volumes, primarily FRC, ERV, and RV, likely due to diaphragm elevation and increased intrathoracic blood volume.
- These findings highlight significant respiratory system adaptations to the microgravity environment.
- Further research is needed to understand long-term implications for space exploration.