Charles JB, Bennett BS.
Aviat Space Environ Med. 1991 May; 62: 454.
Space Biomedical Research Institute, NASA Johnson Space Center, Houston, TX 77058.
INTRODUCTION. Headward fluid shifts occur in Shuttle crewmembers as a result of the elimination of intra-vascular hydrostatic pressure gradients in weightlessness. A non-invasive technique was used to estimate central venous pressure (CVP) during short duration missions to document fluid shifts over time. METHODS. Volunteer crewmembers estimated CVP while supine or weightless by monitoring jugular venous flow with a Doppler probe while exhaling into a mouthpiece. When a transient interruption in venous flow occurred, the mouthpiece pressure was taken as CVP. Data was recorded in a log and on a TEAC HR-30E cassette data tape recorder. All analysis occurred post flight. RESULTS. Preliminary data indicate estimated CVP was slightly decreased 8hr into weightlessness, slightly increased after 1d, and returned to normal preflight values at 2d. From 2-5d, estimated CVP values decreased, approaching a new steady state value approximately half of the preflight values. CONCLUSIONS. The headward fluid shift in weightlessness redistributes blood volume into the central circulation early in flight, which persists for about 2d. This acts as an on-going stimulus for fluid volume reduction which is well established by flight day 2. The new steady state value for CVP is achieved by flight day 4-5, indicating that the astronauts' fluid volumes have adapted to in-flight metabolic requirements by that time.
Publication Types:
Keywords:
- Astronauts
- Blood Volume
- Central Venous Pressure
- Monitoring, Physiologic
- Space Flight
- Weightlessness
- Weightlessness Countermeasures
- Weightlessness Simulation
- NASA Center JSC
- NASA Discipline Cardiopulmonary
- NASA Discipline Number 00-00
- NASA Discipline Number 14-10
- NASA Program Flight
- NASA Program Space Physiology and Countermeasures
Other ID:
UI: 102212712
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