Space flight can stop and even reverse the blood flow in the upper bodies of astronauts. This is an amazing discovery that has important implications for future voyages to Mars and other long-term missions.
NASA has been known for decades Aerospace space is a heavy burden on the body, and a prolonged stay in orbit that is not subject to gravity can cause the muscles of the astronauts to lose mass and their bones become more brittle that staying in space can influence how blood flows through a large blood vessel in the upper body, causing it to stop or even backward – a health risk that was previously unknown.
In the study published in JAMA on Wednesday, the medical journal Network Open, published by the American Medical Association, examined eleven healthy astronauts who had spent an average of six months aboard the International Space Station. Routine ultrasound examinations revealed that on the 50th day of their mission, seven crew members had stagnant or reverse blood flow in their left internal jugular vein, a major blood vessel that runs along the side of the neck and is responsible for draining blood from the brain, face and neck.
An astronaut also developed a clot in the internal jugular vein during space travel, and part of the clot was discovered after returning to Earth in another crew member. [1
"This was an unexpected discovery," said Michael Stenger, manager of the Cardiovascular and Vision Laboratory at NASA's Johnson Space Center in Houston and lead author of the study. "We did not expect congestion and reflux. That is very unusual. On Earth you would immediately suspect a massive blockage or a tumor or something similar. "
The results have significant implications for long-term space missions, including flights to Mars, which would require an interplanetary journey of up to eight years months.
"It may be a serious problem," Dr. Andrew Feinberg, a professor of medicine at the Johns Hopkins University School of Medicine, who was not involved in the new study but had previously been involved in research into the health effects of NASA astronaut Scott Kelly's one-year mission on the space station. "If you get a clot in the internal jugular vein, the clot could travel into the lungs and cause a pulmonary embolism – that's very dangerous – if that happens on a long-term mission, it can be catastrophic."
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Research began several years ago, when NASA attempted to investigate why nearly two-thirds of astronauts spent months on the planet In some cases, these visual problems persisted even after the astronauts returned to Earth.
Stenger and his colleagues should understand how the weightless environment affects the circulation of fluids in the upper body found out that some astronauts without the ubiquitous tug-of-war n Gravity on Earth had difficulty draining the fluids normally, "Stenger said. "Sometimes veins appear on the neck or in the head, which is especially the case with bald astronauts."
In the study, the astronauts were ultrasonographically scanned to measure their left inner jugular vein before takeoff, approximately 50 days after launch into space, 150 days after launch into space, and again approximately 40 days after return to the earth blood flow in this blood vessel.
"If these blood cells do not move, they begin to stick together, and that's what we call a blood clot," he said. "It's the same risk factor if you sit in an airplane too long and clots can form in your legs."
Although the health risks of blood clots are severe, the discovery is not necessarily doomed to failure , Duration space flight.
Dr. Ben Levine, a cardiologist and professor of internal medicine at the Southwestern Medical Center at the University of Texas, Dallas, advised the study and said that the blockages observed in the blood vessels do not necessarily mean that the pressure in them is high.
"Astronauts use their arms a lot to move, so I think a lot of blood flows through the great veins," he said. "I'm intrigued by the results of the study, but not overly concerned."
However, Levine acknowledged that upper body clots could potentially be devastating, adding that further investigation is needed, especially with regard to possible interventions.
In the study, the researchers saw improved blood flow as the astronauts wore a vacuum suit that essentially draws blood from the head to the lower extremities – much as the human body experiences gravity on Earth.
"Space medicine is a journey into extreme physiology – to discover what happens when we leave the earth and how our bodies adapt," Dr. Jan Stepanek, a doctor at the Mayo Clinic in Phoenix, specializing in aerospace medicine. "When we send people on missions to Mars, we need to find appropriate countermeasures to maintain muscle mass and bone density, as well as cardiovascular fitness."
Dr. Scott Parazynski, a doctor and retired NASA astronaut who completed five space shuttle missions but was not involved in the investigation, said he was worried about the potential consequences of the study's findings but was not concerned about flying in the study Space would deter.
] "I do not know that it would change my desire to go to Mars, but it adds to the list of risks," he said. "However, I am encouraged that we can approach the root cause and eventually treat it."
Stepanek added that research shows how much more scientists need to learn about health impacts of travel to space.
"It's humble," he said. "After 50 years of human spaceflight, we may think we know everything, but it turns out that nature surprises us."