How is medicine practiced in space?
Dr. Kris Lehnhardt explains how the near absence of gravity affects human health
Dr. Kris Lehnhardt (@AerospaceMD) is an Emergency Physician and Assistant Professor at The George Washington University School of Medicine and Health Sciences, where he is also the Director of the Fellowship in Extreme Environmental Medicine and the Director of the Introduction to Human Health in Space course. In addition, he is a reservist in the Royal Canadian Air Force, an FAA Aviation Medical Examiner, and an Adjunct Professor at the International Space University.
On May 25, Dr. Lehnhardt answered questions from our community of over 1 million healthcare professionals. You can read the entire Q&A on Figure 1.
Monitoring Human Health in Space
In the Q&A, Dr. Lehnhardt first explained that the medical screening for professional astronauts (e.g., at NASA) is extremely intensive: “There are a lot of medical conditions that are disqualifying for the astronaut corps, such as heart disease or epilepsy. Testing can include CT scans, MRIs, X-rays, colonoscopies, blood tests, urine tests, metabolic screening, fitness tests, etc. They basically look at everything.”
Once in space, astronauts are frequently monitored on the International Space Station, “especially during spacewalks and daily exercise periods.” Dr. Lehnhardt further explained that “in the beginning of human spaceflight, NASA had to create new technologies to remotely monitor human health in space. Many of these technologies were the start of all modern medical monitoring systems used today around the world.”
In space, the near absence of gravity affects many body systems. Dr. Lehnhardt listed problems such as bone loss, muscle loss, decreased blood volume, anemia of spaceflight, decreased cardiac muscle mass, decreased baroreceptor responses, space motion sickness, and reduced proprioception and balance. Maintaining bone mass under microgravity is particularly problematic in long-duration missions:
“Historically, astronauts could lose up to 1% of their bone mass per month in space. However, we developed many countermeasures that have dramatically reduced this: 2.5 hours of exercise (aerobic and resistance) 6 days a week + good nutrition + using osteoporosis medications.”
Dr. Lehnhardt did mention one upside to the near absence of gravity: “On Earth, blood pools in our lower body due to gravity when upright. That stasis increases the risk of blood clots. However, in space, blood distributes evenly in your body due to the near absence of gravity. That means that blood is constantly moving around your body in space and it does not pool in any particular area, making blood clots less likely.”
So how is medicine actually practised in space? “The current strategy on the ISS is the military approach to serious illness or injury — stabilize and evacuate. The further away we go from Earth, the harder it is to evacuate, so more robust medical capabilities are essential for mission success.” Dr. Lehnhardt further elaborated on how medical care is limited: “Not all missions have a physician on-board, so each flight has a crew medical officer, which is an astronaut who has completed some medical training on the ground. There is also a paucity of resources, given mass and volume restrictions in spaceflight. The only imaging modality in space is ultrasound.”
How Aerospace Medicine is Changing
One medical student asked how the rise of private spaceflight has affected the role of physicians in aerospace medicine. “Aerospace med has historically been an occupational med specialty but I believe that this is changing,” responded Dr. Lehnhardt. “The number of private companies that want to fly paying individuals into space has increased dramatically. The people that can afford these trips are likely to be older and have more medical issues than career astronauts. […] The combination of poorer health + significantly less training could be tricky. However, I sincerely want everyone to fly. I believe that our job is to help people maximize their fitness & optimize their health before flight.”
To a registered nurse interested in aerospace nursing, Dr. Lehnhardt suggested: “Aerospace nursing is a growing field but one that is hard to break into, similar to aerospace medicine. A great way to get more involved would be to work for a critical care air evacuation team or a pre-hospital flight system.”
Dr. Lehnhardt’s current projects include the uses for hyperbaric oxygen therapy in spaceflight, the management of back and neck pain/injury in spaceflight, treating general orthopaedic injuries in spaceflight, and the medical issues that the first Mars colonists might face in the future.
