Astronaut receives treatment for blood clot during ISS mission
The International Space Station (ISS) almost got an old-fashioned house call after one of the astronauts was diagnosed with a deep vein thrombosis (DVT) in the jugular vein of their neck. The potentially life-threatening blood clot was treated remotely with the help of University of North Carolina Health Care clot expert Dr. Stephan Moll over a three-month period using medicines already aboard the space station.
Since the earliest days of manned spaceflight, keeping space crews healthy has been a major concern. Astronaut candidates undergo a thorough selection process and everything possible is done to make sure that they are fit for flight. Even then, missions have been fraught with crews suffering from space sickness, flu, diarrhea, and other ailments.
Until now, astronaut maladies have been relatively mild, which is good because the nearest emergency room to the ISS is 250 miles and several hours away at the end of a very stressful spacecraft ride. But that changed when an ISS astronaut was performing an ultrasound on their neck as part of a research study to learn more about how body fluid is redistributed in the human body in zero gravity.
For privacy reasons, the name of the astronaut and other details have been withheld, though they were two months into a six-month mission.
Though the astronaut showed no other symptoms, the scan clearly showed the presence of a blood clot in the jugular vein. Such clots can be extremely dangerous because they can dislodge and move into more vital spots like the lungs, cardiac blood vessels, or the brain. Therefore, treatment is literally vital. The problem is that space medicine is still, in many ways, still in its infancy and there aren't any established procedures for treating DVT in zero gravity.
"My first reaction when NASA reached out to me was to ask if I could visit the International Space Station (ISS) to examine the patient myself," says Moll. "NASA told me they couldn't get me up to space quickly enough, so I proceeded with the evaluation and treatment process from here [at the UNC Blood Research Center at Chapel Hill, North Carolina]."
"Normally the protocol for treating a patient with DVT would be to start them on blood thinners for at least three months to prevent the clot from getting bigger and to lessen the harm it could cause if it moved to a different part of the body such as the lungs, Moll added. "There is some risk when taking blood thinners that if an injury occurs, it could cause internal bleeding that is difficult to stop. In either case, emergency medical attention could be needed. Knowing there are no emergency rooms in space, we had to weigh our options very carefully."
If Moll couldn't make a house call, it also wasn't possible to send the preferred blood thinners to the space station, so Moll and a team of NASA doctors were restricted to prescribing the medicines already aboard the ISS, which included a limited supply of the blood thinner Enoxaparin.
Since no more medicine would be available until the next supply mission, Moll prescribed dosages to be administered by subdermal injections over 40 days. Three days after stocks of the blood thinner ran out, a shipment of Apixaban, which is in pill form, arrived by spacecraft, allowing the treatment to extend to a total of over 90 days. During this time, the astronaut conducted more ultrasound scans while Moll consulted by email and phone calls.
"When the astronaut called my home phone, my wife answered and then passed the phone to me with the comment, 'Stephan, a phone call for you from space.' That was pretty amazing," says Moll. "It was incredible to get a call from an astronaut in space. They just wanted to talk to me as if they were one of my other patients. And amazingly the call connection was better than when I call my family in Germany, even though the ISS zips around Earth at 17,000 miles per hour."
Though the treatment seemed to be working, there was still a bit of suspense because the return to Earth involves being exposed to some heavy g-forces and other stresses, so the medical team stopped the doses of Apixaban four days before the astronaut entered the Soyuz capsule. On the day, the astronaut landed safely and made a full recovery, but the lack of symptoms to indicate there was a clot is still of concern to Moll and the NASA medical team.
"Is this something that is more common in space?" asked Moll. "How do you minimize risk for DVT? Should there be more medications for it kept on the ISS? All of these questions need answering, especially with the plan that astronauts will embark on longer missions to the Moon and Mars."
Moll discusses the treatment in the following video.