Thrombus expert collaborates with NASA to study blood flow in zero gravity

(ORDO NEWS) — Are astronauts more likely to form blood clots during space flights due to weightlessness? This is the question NASA is trying to answer with the help of Stefan Moll, MD, professor in the Department of Medicine at the UNC School of Medicine.

A new publication in the journal Vascular Medicine presents the results of a professional surveillance program triggered by the development of deep vein thrombosis (DVT) in an astronaut’s jugular vein, detailed in a 2020 New England Journal of Medicine publication.

Moll was consulted by NASA when a blood clot was discovered during an astronaut flight on the International Space Station (ISS). This was the first time a blood clot was found in an astronaut in space, so there was no established treatment for DVT in zero gravity.

Moll, a fellow at the UNC Blood Research Center and a clinical hematologist, was called upon to bring his knowledge and experience of treating DVT back to Earth. As a result of the telemedicine act, Moll and NASA doctors helped the astronaut get medical treatment for several months until he returned safely to Earth.

The thrombosis in this astronaut was asymptomatic – he did not have any symptoms that could indicate the presence of a blood clot. The clot was discovered when an astronaut performed an ultrasound of his own neck to study how fluid in the body is redistributed in zero gravity.

If not for this study, it is not known what the result could have been. That is why Moll continues to collaborate with NASA, studying the behavior of blood flow and blood clots in space.

“I’ve always been a space enthusiast,” Moll said. “When I was little, I wanted to be an astronaut, so when NASA called me to help, it was just incredible. And it was amazing to continue to work with NASA, doing research on blood clots in space,

Moll and other researchers, led by NASA MD James Pavla, observed 11 astronauts during 2,150 days of weightlessness on the ISS. All astronauts were screened prior to departure from Earth to obtain baseline data on blood flow and the size of blood vessels in the veins of the neck.

After their time in space, the astronauts performed neck ultrasounds led by the radiological team on Earth to track any changes that occurred in zero gravity.

“We expected some changes in blood flow due to the lack of gravity,” Moll said. “Gravity pulls the fluid in your body down. It also creates a force on the blood vessels, and this increased pressure in the veins of the legs causes the fluid from the blood vessels to leak into the soft tissues. You may notice this when you stand for a long time and you get swelling in your ankles.” , feet, and sometimes hands.

” In the absence of gravity, fluids such as blood are redistributed throughout the body. When astronauts arrive in space, the lack of gravity causes the blood vessels in the neck to dilate due to the displacement of fluid into the upper body. As a result, astronauts develop swelling of the neck and face. This is normal and expected.”

Moll and NASA wanted to answer the question of whether this difference in flow and vessel size could put astronauts at risk of developing blood clots. Although abnormal blood flow characteristics were reported in six of the eleven astronauts, none developed blood clots.

However, the discovery of slow blood flow in the neck veins, abnormal echoes on examination, and even backflow of blood in two astronauts raises the question of whether these anomalies may predispose these space travelers to blood clots.

Since this was a small study, scientists cannot draw firm conclusions. Moll says further studies are needed, but due to their complexity and the small number of astronauts who will be involved in future studies, it may take some time to reach definite conclusions.

In the meantime, this study will help determine what medical supplies, such as blood thinners, should be available for current and future spaceflight. The findings will also help guide the use and development of interventions to minimize the potentially increased risk of blood clots during spaceflight.


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