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Jugular venous flow dynamics during acute weightlessness
Karina Marshall-Goebel1, Stuart M C Lee2, Jason R Lytle2
1NASA Johnson Space Center, Houston, Texas, United States.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|March 14, 2024
Summary
Spaceflight causes fluid shifts, leading to internal jugular vein (IJV) distension. Acute weightlessness further increases IJV size and can cause flow stasis in the left IJV, potentially increasing thrombosis risk.
Area of Science:
- Cardiovascular Physiology
- Space Medicine
- Venous Hemodynamics
Background:
- Spaceflight induces cephalad fluid shifts, altering venous hemodynamics.
- Internal jugular vein (IJV) distension and potential thrombosis risk are concerns during space missions.
Purpose of the Study:
- To investigate the effects of acute weightlessness (0-G) on IJV dimensions and blood flow dynamics.
- To assess changes in IJV cross-sectional area (CSA) and flow patterns during parabolic flight.
Main Methods:
- Two-dimensional (2-D) ultrasound measured IJV CSA.
- Doppler ultrasound characterized venous blood flow patterns.
- Measurements were taken in seated, supine (1-G), and supine (0-G) conditions during parabolic flight.
Main Results:
- Supine posture increased IJV CSA on Earth (1-G).
- Entry into 0-G further increased IJV CSA bilaterally compared to supine 1-G.
- Flow stasis was observed in the left IJV of one participant during 0-G, persisting during level flight.
Conclusions:
- Acute weightlessness alters cerebral outflow dynamics in the left IJV.
- These alterations may elevate the risk of venous thrombosis during spaceflight.
- IJV distension and potential flow stasis are significant findings for astronaut health.
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