Space travel destroys astronomical amounts of red blood cells

Space is not an easy environment for human beings and it turns out that astronauts return to Earth with a well-studied side effect: space anemia. A blood flow study conducted by Guy Trudel, a specialist in physical medicine and rehabilitation at the Ottawa Hospital, and a team of scientists from the University of Ottawa in Canada, has shed more light on this phenomenon. . By analyzing blood and breath samples, they discovered that once in space, more than 50% of astronauts’ red blood cells (which carry oxygen from the lungs) were destroyed.

“When astronauts come back from space, they look a lot like the patients we admit to rehab”, testifies Guy Trudel with Ars Technica magazine. He explains that something in space causes the human body to hemolyse – that is, to break down red blood cells – at a higher rate than on Earth. According to the results of the study, three million red blood cells are destroyed every second. This is 54% more than what happens in the human body on our planet, where this figure is around two million per second.

In space, the human body can perfectly be satisfied with this loss since it manages to self-balance and thus maintain a concentration of red blood cells at acceptable levels. But when an astronaut returns to Earth, his body is confronted with the force of gravity.

Study the breath of astronauts

To study space anemia, Guy Trudel worked with fourteen astronauts on a six-month mission to the International Space Station (ISS). They blew into special cartridges so that their breath was preserved at four predefined intervals: at five days, twelve days, three months and finally just before returning home, at six months. Upon their return, the researchers examined the samples using a high-resolution gas chromatograph, a machine that measures the amount of carbon monoxide – produced each time a red blood cell is hemolyzed in the body. . The results of the study allowed scientists to assess the major loss of red blood cells in the blood.

After their trip, five of the fourteen astronauts who had their blood drawn on landing were still clinically anemic. Three or four months after their return, the production of red blood cells had resumed, but a year later, the astronauts’ hemolysis rate was still 30% higher. According to Guy Trudel, the longer astronauts stay in space, the greater the anemia once they return to solid ground.

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The team does not yet know exactly why space causes this reaction. However, she thinks that the destruction of blood cells can come from a problem in the bone marrow (where red blood cells are made), in the blood vessels, in the liver or in the spleen. “What causes anemia is hemolysis, but what causes hemolysis is the next step [à découvrir]», says Guy Trudel. The results will be accurately communicated to warn future space travelers. People with heart problems, angina pectoris or abnormal hemoglobin levels could obviously be considered at risk.

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