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Pulmonary diffusing capacity and pulmonary capillary blood volume during parabolic flights
1Laboratoire de Physiologie, Médecine Aérospatiale, Université Bordeaux 2, France. pierre.vaida@u-bordeaux2.fr
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 1, 1997
Summary
Microgravity rapidly increases pulmonary diffusing capacity (DL) and pulmonary capillary blood volume. These rapid changes during parabolic flights suggest significant physiological adaptations occur at the onset of weightlessness.
Area of Science:
- Physiology
- Aerospace Medicine
- Respiratory System
Background:
- Previous Spacelab missions showed moderate increases in pulmonary diffusing capacity (DL) after 24 hours of microgravity.
- Occupational constraints limited data collection to sustained microgravity exposure.
Purpose of the Study:
- To investigate immediate changes in DL and related lung parameters at the onset of weightlessness.
- To compare acute microgravity effects with those observed during sustained exposure.
Main Methods:
- Ten male subjects underwent measurements during 20-second zero-gravity phases of parabolic flights.
- The single-breath technique was used to simultaneously measure DL for carbon monoxide (CO) and nitric oxide.
- Pulmonary capillary blood volume and membrane diffusing capacity were also assessed.
Main Results:
- Significant increases were observed in DL for CO (62%) and nitric oxide (47%).
- Membrane diffusing capacity for CO increased by 47%.
- Pulmonary capillary blood volume showed a substantial increase of 71%.
Conclusions:
- Major adaptations in alveolar membrane gas transfer and pulmonary capillary bed occur immediately upon entering microgravity.
- These acute effects are considerably larger than those seen in sustained microgravity, questioning the comparability of parabolic flight data for long-term effects.