Astronauts: Blood clot expert to study blood flow, clot formation in
zero gravity

Date:
May 3, 2022
Source:
University of North Carolina Health Care
Summary:
This was the first time a blood clot had been found in an astronaut
in space, so there was no established method of treatment for DVT
in zero gravity.



FULL STORY ==========================================================================
Are astronauts more likely to develop blood clots during space missions
due to zero gravity? That's the question NASA is trying to answer with
help from UNC School of Medicine's Stephan Moll, MD, professor in the
UNC Department of Medicine. A new publication in Vascular Medicineshows
the results of an occupational surveillance program spurred by the
development of a deep vein thrombosis (DVT) in the jugular vein of an astronaut, which is described in detail in a New England Journal of Medicinepublication from 2020.


==========================================================================
Moll was consulted by NASA when the discovery of the blood clot was
made during the astronaut's mission on the International Space Station
(ISS). This was the first time a blood clot had been found in an astronaut
in space, so there was no established method of treatment for DVT in
zero gravity. Moll, a member of the UNC Blood Research Center and a
clinical hematologist, was called upon for his knowledge and treatment experience of DVT on Earth. In the ultimate act of telemedicine, Moll
and NASA physicians helped treat the astronaut over several months,
until they safely returned to Earth.

This astronaut's blood clot was asymptomatic -- they didn't have any
symptoms that would have otherwise indicated there was a clot. The DVT
was discovered when the astronaut was taking ultrasounds of their own
neck for a research study on how body fluid is redistributed in zero
gravity. If it wasn't for the study, there's no telling what the outcome
could have been. That's why Moll has continued to work with NASA to
research how blood flow and blood clots behave in space.

"I've always been a space enthusiast," Moll said. "When I was young I
wanted to be an astronaut, so when NASA called on me to help, it was
pretty incredible.

And it's been amazing to then continue working with NASA doing research
on blood clots in space that will help develop the health and safety
protocols for future space travel." Moll and fellow researchers, led
by NASA's James Pavela, MD, monitored 11 astronauts over a combined
total of 2,150 days in zero gravity on the ISS. All astronauts were
evaluated before leaving Earth to get a baseline of their blood flow and
blood vessel size in the veins of their neck. Once in space, astronauts performed ultrasounds on their own necks with guidance from a radiology
team on Earth to monitor any changes that occurred in zero gravity.

"We expected some changes in flow based on the absence of gravity,"
Moll said.

"Gravity pulls fluid in your body down. It also creates a force on your
blood vessels and this increased pressure in the veins of the legs leads
to leakage of fluid from the blood vessels into the soft tissues. You
can notice this when you stand for a long time and develop swelling in
your ankles, feet, and sometimes hands.

"Without gravity, fluids like blood redistribute in your body. When
astronauts arrive in space, the lack of gravity causes the blood
vessels in the neck to expand due to fluid shifting to the upper part
of the body. Astronauts develop swelling of the neck and face from this
shift. That is a normal and expected finding." The question Moll and
NASA wanted to answer is if this difference in flow and vessel size
could put astronauts at risk for the development of blood clots.

While abnormal flow characteristics were recorded in six of the eleven astronauts, none developed blood clots. However, the findings of slowed
blood flow in the neck veins, abnormal echo findings on the examination,
and even reversal of blood flow in two astronauts raises the question
whether these abnormalities could predispose these space travelers to
blood clots.

Because this was a small study, researchers cannot make firm
conclusions. Moll says more research is needed, but due to the challenges
of such investigations and the small pool of astronauts to participate
in future studies, it may take some time to draw definite conclusions.

In the meantime, this research helps inform what medical supplies, like
blood thinners, should be available for current and future spaceflight missions. The data will also help guide the use and development of interventions designed to minimize the potentially increased blood clot
risk of spaceflight.

This study was funded by NASA.


========================================================================== Story Source: Materials provided by
University_of_North_Carolina_Health_Care. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. James Pavela, Ashot Sargsyan, Deepak Bedi, Aaron Everson, Jacqueline
Charvat, Sara Mason, Benjamin Johansen, Karina Marshall-Goebel,
Sarah Mercaldo, Ronak Shah, Stephan Moll. Surveillance for
jugular venous thrombosis in astronauts. Vascular Medicine, 2022;
1358863X2210866 DOI: 10.1177/1358863X221086619 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/05/220503102850.htm

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