Surveillance for jugular venous thrombosis in astronauts

Area of Science:

• Space medicine
• Cardiovascular physiology
• Venous thromboembolism

Background:

• A case of left internal jugular vein thrombosis in an astronaut highlighted potential risks during spaceflight.
• Flow abnormalities in neck veins are common in microgravity.
• The National Aeronautics and Space Administration (NASA) established an occupational surveillance program for astronaut venous thrombosis.

Purpose of the Study:

• To evaluate astronauts for venous thrombosis using duplex ultrasound.
• To assess hemodynamic changes in internal jugular veins during spaceflight.
• To identify potential risk factors for thrombus formation in astronauts.

Main Methods:

• Duplex ultrasound of bilateral internal jugular veins was performed on astronauts terrestrially and during spaceflight.
• Respiratory maneuvers were utilized during ultrasound examinations.
• Images were analyzed for thrombosis, peak velocity, echogenicity, and blood flow patterns.

Main Results:

• No thrombosis was detected in the evaluated astronauts.
• In-flight peak blood flow velocity in the internal jugular veins was reduced compared to terrestrial measurements, particularly in the left vein.
• Six astronauts showed mild-moderate echogenicity in the left internal jugular vein during spaceflight, and two experienced retrograde blood flow.

Conclusions:

• Abnormal blood flow characteristics, especially in the left internal jugular vein, were observed in microgravity.
• These findings suggest a potential increased risk for thrombus formation in some astronauts during spaceflight.