Calling an ambulance in an emergency or getting to the nearest hospital can sometimes be tricky, but what if you need medical attention and you're on board the International Space Station? This was the case with an undisclosed NASA astronaut.
During his stay on the ISS, the astronaut was found to have deep vein thrombosis - a blood clot in the jugular vein in the neck. Since the blood clot could travel to other places, such as the lungs, heart vessels, or the brain, the situation was life-threatening.
NASA could not foresee such a situation, therefore, the department's specialists did not have a developed method of treating thrombosis in zero gravity. They consulted Stefan Moll, MD and renowned thrombosis specialist.
“When NASA contacted me, my first reaction was to ask if I could visit the ISS and personally examine the patient? But the department told me that they could not send me into space quickly enough, so I started assessing the astronaut's condition and planning treatment directly from Earth,”- Stefan Moll.
“The usual protocol for treating patients with deep vein thrombosis is to use blood thinners for at least three months. This should prevent the clot from growing and reduce the damage it can cause by moving to another part of the body, such as the lungs.
But with these drugs, there is some risk that internal bleeding will occur in the event of an injury, which will be difficult to stop. In such cases, emergency medical care may be required, and there are no such departments in space. So we had to weigh all the options very carefully,”explains Moll.
Of the funds available on board the ISS, there was a certain amount of enoxaparin, which the astronaut began to take until NASA was able to deliver other necessary drugs aboard the spacecraft. The course of treatment with enoxaparin injections lasted about 40 days, and on the 43rd day of treatment, apixaban tablets were delivered to the ISS, which the patient took orally.
During the entire treatment process, which lasted more than 90 days, the astronaut performed an ultrasound scan on his own neck under the guidance of a radiological team on Earth to control the blood clot. Moll also communicated with the astronaut during this period by email and phone.

“When the astronaut called me on my home phone, my wife answered the phone, and then handed it to me with the comment:“Stefan, this is a phone call from space.” It was pretty amazing. He just wanted to talk to me like he was one of my other patients. And surprisingly, the connection was even better than when I called my family in Germany, despite the fact that the ISS is moving around the earth at a speed of 17 thousand miles per hour,”says Moll.
Four days before returning to Earth, the astronaut stopped taking medication to avoid the negative effects of overload upon landing. A study carried out already on Earth showed that the thrombus does not need further treatment and does not pose a danger to the patient's life.
NASA emphasizes that thrombosis was asymptomatic, and it was detected only thanks to ultrasound of the neck during a study of how body fluids are redistributed in zero gravity. If not for this survey, it is impossible to say what the result would have been. So Moll is working with NASA to learn more about how blood and blood clots behave in space.