NASA has created a new algorithm to assess venous thromboembolism (VTE) risks for astronauts, recommending prophylaxis based on blood flow stasis and other weighted factors.

NASA’s Office of the Chief Health and Medical Officer (OCHMO) has developed a VTE Risk Score for Astronauts Algorithm to mitigate blood clot risks during spaceflight. The initiative follows the diagnosis of venous thromboembolisms in astronauts during International Space Station missions, prompting a review of clinical practice guidelines and research into altered blood flow in microgravity.

Risk Factors and Clinical Recommendations

The working group identified stasis in the left internal jugular vein as a primary risk factor for VTE in microgravity. While experts continue to debate the specific contributions of retrograde flow and endothelial factors, the panel reached a consensus that both stasis and retrograde flow warrant the use of prophylactic treatment. The new algorithm also incorporates other weighted thrombosis risk factors derived from terrestrial medical literature to determine when anticoagulation is necessary.

Addressing Diagnostic Limitations

The panel expressed concerns regarding the current limitations of in-flight ultrasound technology in accurately measuring slow blood flow. Because relying solely on stasis as a diagnostic indicator presents challenges, the working group recommended further research into assessing stasis via in-flight ultrasound to improve diagnostic accuracy and clinical decision-making.