International Space Station
(Photo courtesy of NASA)

Astronaut with blood clot in space prescribed treatment via ultrasound

January 03, 2020
by John R. Fischer, Senior Reporter
One physician in North Carolina has helped push the boundaries of telemedicine beyond our atmosphere — literally — by using it to diagnose a blood clot in space.

NASA recruited Dr. Stephan Moll, a professor of medicine at the University of North Carolina School of Medicine and a co-founder of the UNC Blood Clot Education Program, Clot Connect, to assess one of its astronauts aboard the International Space Station (ISS) after a deep vein thrombosis (DVT) was discovered in the jugular vein of their neck.

“My first reaction when NASA reached out to me was to ask if I could visit the International Space Station (ISS) to examine the patient myself,” said Moll in a statement. “NASA told me they couldn’t get me up to space quickly enough, so I proceeded with the evaluation and treatment process from here in Chapel Hill.”

The clot was the first of any to be found in space, and was discovered when the astronaut took an ultrasound of their neck as part of a research study to examine how body fluid is redistributed under zero gravity conditions. The DVT was asymptomatic, with the individual exhibiting no signs. Neither the astronaut’s name nor the time in which clot was discovered has been disclosed.

With no established protocol for treating DVT in space, NASA reached out to Moll. He and a team of doctors at the federal agency determined a course of blood thinners as an effective treatment. The ISS, however, had only a limited amount of Enoxaparin (Lovenox), a blood thinner injected into the skin. Moll recommended a dosage that would treat the DVT long enough until a new shipment of drugs could be delivered to the ISS.

The astronaut was administered Enoxaparin daily for 40 days. On the 43rd day of treatment, a supply of Apixaban (Eliquis), an oral blood thinner, was delivered and provided to the astronaut for the rest of their treatment, which took more than 90 days. During that time, an earth-based radiology team monitored the blood clot by guiding the astronaut in performing ultrasounds on their own neck. Moll consulted the patient via email and by phone.

"The extreme example of telemedicine for this astronaut — for diagnostic purposes, but more so for management discussion and decision-making — documents, in the extreme, how telemedicine can lead to a solid treatment plan and enable state-of-the-art management even over a huge distance," Moll told HCB News. "It is, therefore, a sort-of poster child, an 'advertisement' and a discussion-opener to create structures in our health care system that make effective telemedicine an easy possibility."

While effective in treating blood clots, blood thinners run the risk of contributing to internal bleeding in the event of an injury to the patient. It is because of this risk that Moll and his NASA counterparts stopped the patient’s course of Apixaban four days before they were due to return to earth. As the re-entry process is physically demanding and can be potentially dangerous, they did not want the blood thinners to exacerbate any injuries that may occur upon landing.

The astronaut’s return was completed safely, with the clot deemed no longer in need of treatment. Moll says the event stresses the need for more research on the behavior of blood and blood clots in outer space.

"In space (as well on Earth) we have limited knowledge why blood clots — deep vein thrombosis (DVT) or pulmonary embolism (PE) — occur in a given individual," he said. "What are the risk factors? How do you predict who will develop a clot? What are the mechanisms of blood clot formation? Are blood clots in space clinically relevant or just an irrelevant coincidental phenomenon? How do you (and do you need to) prevent blood clots, particularly on long flights, such as to the Moon or to Mars? How do you best treat blood clots if they occur? ... These are some of the questions that need to be (and are being) discussed, studied, and answered."

The events and findings of the diagnosis and treatment were recorded in a case study published in the New England Journal of Medicine.