The news went around the world: one of the astronauts working on the ISS ended up with a blood clot inside the jugular vein. The causes are certainly related to the long time spent in an environment of microgravity, a condition with which the human body is not naturally predisposed to live.
A blood clot is a very delicate medical condition even here on Earth, but when we are 408km from the Earth's surface the situation becomes even more critical.
There is always a problem
To resolve the problem, NASA contacted Dr. Stephan Moll, blood clot expert from the UNC School of Medicine in North Carolina and above all, a doctor not internal to NASA. Dr. Moll says his first reaction when NASA contacted him was to ask if he could to reach the patient and then land on the International Space Station (ISS) for a direct examination.
However, the procedure for making a non-astronaut human being eligible to travel is a lot long and complex, therefore in the end we proceeded to the examinations and evaluations conducted in distance: the doctor was in Chapel Hill, North Carolina.
When Dr. Moll (pictured above) was told that an astronaut aboard the ISS was suffering from a deep vein thrombosis (TVP) in the jugular vein of the neck, he was also informed that the astronaut's identity had to remain anonymous for privacy reasons, therefore both the name of the astronaut involved, and the dates relating to the report and the visit, are omitted from the various reports.
The first case in space
The event was important: is the first time that a blood clot is found in an astronaut in space, so until a few days ago there was still no established treatment methodology for DVT to zero gravity.
Usually, the protocol for treating a patient with TVP would be to start a blood thinner cure for at least three months to prevent the clot from getting bigger and to reduce the damage it could cause if it started to wander and reach another part of the body such as the lungs.
However there is a risk, when taking blood thinners, that in case of even minor injuries (such as simple cuts on the skin), these can easily evolve into internal bleeding difficult to arrest. However, emergency medical care may be required during these procedures. And it is for this reason, bearing in mind that there is no first aid in space, that several factors had to be taken into consideration before proceeding with the treatment.
Moll and a team of NASA doctors decided that i blood thinners would have been the best solution for the astronaut. However, they were limited by the "pharmaceutical stocks" available on board the international space station. The ISS has only one on board small supply of medicines, to cover a little 'all the eventualities, and in particular there was a small amount of Enoxaparin, blood thinning medicine.
This made the organization of one necessary cargo mission to deliver new stocks of medicines. Treatment with Enoxaparin, a drug that is administered through injection, lasted for about 40 days. On day 43 of the treatment, the astronaut then had to take Apixaban, a pill that should be taken for orally, delivered to the ISS always through the cargo vehicle specially launched from Earth.
When the sums are drawn
Throughout the treatment process, which lasted longer than 90 days, the astronaut performed ultrasound checks on his neck with the guidance of a radiology team on Earth, in order to monitor the evolution of the blood clot. During the therapy, Dr. Moll was also able to speak to the astronaut via email and phone calls.
The reason for this choice is extremely "human": in those conditions, comfort and reassurance are extremely useful for a tired mind like that of an astronaut, who could experience moments of discouragement given by the distance from home and the exaggerated conclusions that would be brought to think realizing that the ISS is not really an emergency room.
Dr. Moll says that "it was incredible to receive a call from an astronaut in space. He just wanted to talk to me like he was one of my other patients. And surprisingly the call connection was better than when I call my family in Germany.".
Four days before the astronaut's return journey to Earth, Apixaban's intake is then stopped. Moll and the NASA team made this decision by virtue of some considerations on the re-entry process, and how the descent phase can be physically demanding and potentially dangerous for astronauts. There was a desire to prevent any injury from worsening under the effect of blood thinners. The astronaut landed safely on Earth and eventually the blood clot no longer required medical attention.
But didn't they notice?
The blood clot of this astronaut was asymptomatic, which is why the medical evaluation team did not notice his presence before departure. The astronaut showed no symptoms and the DVT was only discovered when he found himself performing ultrasound analyzes on the neck, during a study on the ways in which body fluids (in particular blood) are redistributed in zero gravity. If it weren't for this experiment, the astronaut would have faced a worse fate.
That's why Dr. Moll continues to work with NASA from now on and says further research is needed to fully understand how blood and blood clots behave in space.
"It is something that is more common in space? "Moll asked."How to minimize the risk of DVT? Should there be multiple drugs kept for it in the ISS? All these questions need to be answered, especially when astronauts undertake longer missions to the moon and Mars."
A study to collect ideas
Serena Auñón-Chancellor, associate professor of medicine at LSU Health, the campus of the School of Medicine of New Orleans in Baton Rouge, is the main author of the article describing the case of the clot on the ISS, published on January 2, 2020 in New England Journal of Medicine.
Eleven astronauts were involved in the vascular study, which sought to fill in the gaps on circulatory physiology. These studies will not only benefit patients on Earth, but could be critical to astronauts' health during future space exploration missions on the Moon and Mars.
In particular, the study collected data on the structure and functioning of the internal jugular vein in a long-lasting space flight, in which astronauts are exposed to continuous changes in the flow of blood and tissue fluids.
Ultrasound examinations of the astronauts' internal jugular veins were performed at scheduled times during the mission, thus bringing to light the clot problem.
The article highlights a particular aspect of zero-gravity injections: the withdrawal of liquids from the vials represented a significant challenge due to the effects of surface tension. Furthermore, although the size of the clot has progressively decreased, the spontaneous blood flow was still absent after 90 days of anticoagulant treatment.
The astronaut was thus brought back to Earth. Upon landing, an ultrasound showed the clot flattened on the walls of the blood vessel, therefore without the need for further care. The clot was still present 24h later the landing, but within ten days it was correctly eliminated by the body. The biggest question that remains is: how can you deal with such an emergency on a long-term mission to Mars?
