Proposed mechanism for reduced jugular vein flow in microgravity
Mimi Lan1, Scott D Phillips2, Veronique Archambault-Leger2
1Thayer School of Engineering at Dartmouth, Hanover, NH, USA.
Physiological Reports
|May 1, 2021
Summary
Reduced internal jugular vein (IJV) flow in space increases thrombosis risk. Microgravity alters transmural pressure, raising IJV resistance and decreasing flow, unlike the vertebral plexus. This finding impacts astronaut health during long-duration spaceflights.
Area of Science:
- Cardiovascular Physiology
- Space Medicine
- Fluid Dynamics
Background:
- Internal jugular vein (IJV) flow reduction in microgravity is linked to thrombosis risk.
- The underlying mechanisms for this flow change and thrombosis risk are not fully understood.
- Preventing serious vein thromboses is crucial for long-duration spaceflights.
Purpose of the Study:
- To investigate the mechanisms behind reduced internal jugular vein (IJV) flow in microgravity.
- To develop hypotheses for IJV flow changes using a novel numerical model.
- To understand the implications for venous thrombosis risk in astronauts.
Main Methods:
- Development of a novel, microgravity-focused numerical model of cranial vascular circulation.
- Inclusion of effects from removed hydrostatic gradients and tissue compressive forces.
- Modeling IJV sensitivity to transmural pressure and comparing it with the vertebral plexus.
Main Results:
- The model predicts reduced IJV flow in space due to increased resistance.
- Loss of hydrostatic pressure and tissue gradients outweighs reduced neck tissue weight, leading to negative transmural pressure.
- Vertebral plexus flow increases in microgravity as its resistance is unaffected by transmural pressure.
Conclusions:
- Reduced IJV flow in space is attributed to increased venous resistance caused by microgravity-induced changes in transmural pressure.
- Interventions decreasing IJV pressure without gravitational assistance may increase thrombosis risk.
- Findings are supported by spaceflight measurements showing reduced IJV area inflight.
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