Retrograde Jugular Vein Blood Flow In Space

Exposure to a weightless environment during spaceflight results in a chronic headward blood and tissue fluid shift compared with upright posture on Earth. To investigate the association of the change with cerebral venous outflow, researchers obtained jugular vein ultrasonography of healthy crew members participating in long-duration spaceflight missions to the International Space Station. Stagnant and/or reverse internal jugular vein flow was observed in 6 of 11 crew members on flight day 50. This ultrasonography video illustrates an example of retrograde (grade 4) flow; blood in the internal jugular vein is flowing in the reverse direction (toward the head, left). Click to view a video example of stagnant internal jugular venous flow and for full details of the investigation.