Why astronauts may face a hidden blood clot risk in space | – The Times of India

As we explore more of the universe, the physical impacts of living in microgravity continue to be one of the primary obstacles to long-term space travel. Research on Assessment of Jugular Venous Blood Flow Stasis and Thrombosis During Spaceflight suggests that astronauts may face a potential “silent” risk of developing Venous Thromboembolism during long-duration space missions due to changes in blood flow in microgravity. On Earth, gravity pulls fluid down to our lower legs, but while in orbit, fluids shift upwards tremendously, and blood can pool within the internal jugular veins with little flow due to being in a weightless environment. In microgravity, blood that pools in the neck veins and moves more slowly could increase the conditions that allow clots to form, although scientists are still studying how different biological factors may influence this risk during spaceflight. According to the Human Research Program managed by NASA, managing these blood flow issues is critical to keeping astronauts safe during possible longer journeys to Mars.

Why space travel confuses the human heart

Microgravity significantly alters the way that blood flows through the body, and in particular, how it is affected by pressure forces from the internal jugular vein. Gravity provides down force to carry blood from the head to the heart. However, without the presence of gravity, a ‘fluid shift’ occurs, and blood collects in the upper chest area. This has been shown to slow down or completely reverse the direction of blood flow in the neck (internal) jugular veins. Research published in JAMA Network Open revealed that blood that has been stagnant in this way creates a high-risk environment for thrombus (clotting) formation; these clots could potentially travel to the lungs and create a serious embolic event.

Why space clots are different

According to the research study, blood clots have a physical appearance that could be altered based on the environmental conditions in which they form (i.e. gravity). In the microgravity environment of space, blood clots can have thicker fibrin networks and be more resistant to the body’s natural ability to break down clots. Scientists are continuing to study how microgravity might influence clot formation and treatment, although standard anticoagulant medications have already been used successfully to treat a clot detected in an astronaut during a mission.

Can astronauts exercise to prevent these clots

Walking on Earth promotes the circulation of blood in the legs and, therefore, aids in the prevention of the formation of clots. In space, astronauts perform resistance exercises using a special piece of equipment called the ARED (Advanced Resistive Exercise Device) to simulate the force of gravity that should be acting on their bodies, and the weight being applied to their body while the astronaut trains with the ARED will continue to be transmitted to the bones and muscles. While performing these resistive exercises will protect the bones and muscles of the astronaut, they do not relieve the ‘fluid shift’ that occurs from the lower point of the body up through the neck area. NASA is currently testing a technology called Lower Body Negative Pressure (LBNP), which uses special pants designed to create a vacuum and ‘suck’ the blood back down into the lower legs, thus relieving the pressure in the jugular vein.

How do they detect a ‘silent’ clot in orbit

Because there are no full medical facilities in orbit, astronauts perform many diagnostic procedures themselves while physicians on Earth guide them remotely. The principal instrument used by astronauts to diagnose the health of crew members is high-resolution ultrasound (HRUS). The HRUS is performed remotely with the astronauts operating the HRUS instruments and a physician on Earth providing the astronaut with instructions through a two-way video connection. The first instance of an asymptomatic clot in space was discovered in 2019 as part of a routine research study using HRUS, and not because the astronaut was symptomatic with an illness.