I have been interested in space exploration since I was a child. I have also read a lot of science fiction. The possible deleterious effects of prolonged time orbiting the Earth has seldom been raised either in academia or in fiction. But a lot of documentation has accumulated with respect to astronauts’ heath that suggests that greater attention should be paid to the changes wrought by space travel on the human body.
New research has found serious health problems in the bodies of astronauts aboard the International Space Station (ISS). The implications for long term health are still being studied but it appears that there are problems with bones, hearts, eyes and now blood flow.
A new study from NASA has identified a new danger in space. Low gravity can make blood flow stop and actually go in reverse in some astronauts. The condition is particular severe in astronauts’ upper bodies. This was the conclusion of a study that examined data from eleven astronauts who spent an average of six months each on the ISS. There were nine men and two women in the study.
Ultrasound scans revealed that about the fiftieth day of the mission, seven members of the crew had blood in their internal jugular vein stop flowing or even start going in reverse. The internal jugular vein is a major blood vessel which goes down the side of the neck. The purpose of this blood vessel is to collect blood from the brain, face and neck.
One of the astronauts also developed a clot in the vein while still in orbit. Another was found to have a partial clot upon coming back to Earth. Having your blood flow in reverse constitutes a serous problem. The discovery raises additional concerns about the dangers of long-term space travel.
Michael Stenger is a manager of the Cardiovascular and Vision Laboratory at NASA’s Johnson Space Center in Houston and a coauthor of the report on the study. He called the findings “unexpected”. He said, “We did not expect to see stasis and reverse flow. That is very abnormal. On Earth, you would immediately suspect a massive blockage or a tumor or something like that.”
Stenger attributes the blood flow issue to the absence of gravity. He points to years of observations on physiological changes in astronauts. He said, “This is why some astronauts get puffy faces, because there’s no gravity to pull down those fluids circulating in the upper body. You’ll sometimes also see veins popping out in the neck, or in the head — which you can see with bald astronauts, in particular.” He said that stopped blood flow was probably the most worrisome aspect of the new discovery because it can result in dangerous blood clots.
While the research is troubling, it can be seen as an opportunity to anticipate the risks and develop new treatments and preventative measures. The study is titled “Assessment of Jugular Venous Blood Flow Stasis and Thrombosis During Spaceflight”. It was published in the medical journal Jama Network Open (from the American Medical association.