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As NASA accepts emergency physician Andrew Morgan into the astronaut program, EPM takes a look at space medicine, and why EPs are so well suited for the unpredictable life on the final frontier

On June 17th NASA introduced its 21st class of astronaut candidates. One of the eight newly selected candidates, Dr. Andrew Morgan, is an emergency physician. Morgan, a U.S. Army physician, graduated from the Uniformed Services University of the Health Sciences in Bethesda and has worked at Womack Army Medical Center at Fort Bragg, as well as several special operations postings around the world. He was in a sports medicine fellowship in Virginia when NASA called to tell him he was selected, a moment he described on an Army website as “surreal.” “I couldn’t believe it; the thought that I had been chosen choked me up.”

Dr. Morgan belongs to the first class of Astronauts picked with the expectation that they would be part of the US space program’s exploration missions beyond low earth orbit. Depending on Congressional and Executive branch decisions in the next few years, astronauts like Dr. Morgan may train to go to the Moon, nearby asteroids, and maybe even Mars. NASA’s been looking for professionals who had the background to be able to operate independently and multidisciplinary while far away from any backup.  

It’s no surprise to the space medicine community that an emergency physician was among the eight candidates selected. EPs were very well represented in the final group of people NASA interviewed before selecting the candidates. Not to mention that there have been, and continue to be, many NASA astronauts who are emergency physicians, including Anna Lee Fischer, Thomas Marshburn, Scott Parazynski, and Kjell Lindgren who was selected in the previous class of 2009. This list doesn’t even begin to include the many NASA and other agency flight surgeons who have emergency medicine backgrounds.

There are many reasons that NASA likely feels that emergency medicine training is relevant to the needs of their astronauts, and several papers have been published on the topic. In particular a 2007 paper by Stewart et. al in The Journal of Emergency Medicine “Emergency Medicine in Space” starts with a brief introduction to space medicine and then goes on to discuss emergent surgical and medical management of diseases and trauma in spaceflight. Also of note is a 2005 work by Summers et. al in Annals of Emergency Medicine that surveys the history of medical emergencies in human spaceflight up to 1999, and compares the medical evacuation incident rate of the American and Russian space programs (0.02 and 0.03 events per person-yr respectively) to an analogous environment in Antarctica (0.036 events per person-yr).  

Space, of course, presents some unique challenges to human physiology. The most significant changes to the human body during long duration spaceflight come in the cardiovascular system. When the body enters weightlessness there is a cephalad shift in intravascular fluid from the lower extremities to the trunk and head, giving astronauts the classic “chicken legs” and “baby face” look that is seen when astronauts participate in video chats while in orbit.

Over the long term this reduces the total fluid volume in the body, as baroreceptors in the vasculature respond appropriately to the perceived increased fluid load. The altered hemodynamics are thought to give rise to arrhythmias; at one point it was found that 30% of astronauts doing activities outside of the space shuttle had PACs and PVCs. Following return to a gravitational environment the fluid load shifts back rather rapidly to the normal Earth distribution, leaving most astronauts very orthostatically sensitive for hours to days after landing. This explains why most pictures of space travellers who have just returned from the International Space Station feature them seated.  

Bone and muscle loss is another well known problem in spaceflight. Astronauts lose about 1-2% of Bone Mineral Density from their weight supporting bones (femur, pelvis, spine) per month, and  that is with the current exercise regimen of several hours of resistance exercise a day. This leads to an increased risk of traumatic fracture, and the increased amount of calcium resorption increases the risk of developing kidney stones, however Summers reports only one incidence of renal stones and one of urinary retention. A 2007 case report by Stepaniak in Aviation Space and Enviromental Medicine further relates the story of a male with mission-impacting urinary retention that necessitated several self-catheterizations while in-flight (apparently they stocked 14F Foleys on the shuttle).  

Along with the increased chance of injury and renal pathology, the downregulation of the immune system has been observed in long-duration crews, increasing the risk of infection and latent virus reactivation. Combined with data that shows increased infectivity and virulence of pathogens such as salmonella, the space station is no place to run out of antibiotics. In fact, the confluence of these factors has led to a long running study on the International Space Station devoted to finding a vaccine for Salmonella.

For space missions beyond the Earth’s protective magnetic fields, radiation exposure becomes a concern. Solar radiation events are likely to lead to cataracts and leukemias. Aside from the increased cancer risk, data in the last decade has shown that many astronauts are returning to Earth with permanent vision changes, thought to be due to an increase in intracerebral pressure, though the precise etiology is unclear. Vestibular changes also occur as the astronauts adapt to an environment without a gravitational cue. Sometimes this manifests as “Space Motion Sickness,” a self-limited period of nausea and vomiting that affects more than half of astronauts when they first get into space.

Currently, the medical, imaging, and laboratory capabilities of the International Space Station are limited compared to an average American emergency department. An AED is on board, and some concentrated oxygen, but really not much more than would be expected to be found in a decently outfitted ALS ambulance. Special protocols have been developed to perform intubations and chest compressions when there is no “down” and pushing or pulling moves the healthcare provider just as much as the patient. Complicated pressure systems must be used to deliver fluids when it is impossible to “hang” a bag of saline. Also, the reliability and stability of medication is suspect when the medications have been in the same increased radiation environment as the astronauts themselves.

As dire as all of the above medical issues sound, the combination of the medical selection criteria to become an astronaut and the countermeasures developed after decades of human spaceflight has prevented any loss of life or permanent non-correctable disability from medical or surgical issues in human spaceflight; the Summers review only found 17 total non-fatal severe incidents from 1968-1999. The concern is what happens when less-fit, unscreened paying tourists start to travel to space in greater numbers, or when astronauts start traveling to places where there’s no quick trip home.  Another fear is what could happen if the physician gets sick, leading to a situation seen in 1961 when a Soviet doctor on an Antarctic expedition had to perform a self-appendectomy, assisted by the base’s meteorolgist and driver.

In the current medical training environment, not many other specialties have the breadth of experience that emergency medicine does dealing with aspects of cardiology, endocrinology, orthopedics, hematology, oncology, ENT, neurology, urology, trauma, remote medicine, and psychiatry, and so when NASA and other space agencies go looking for physicians with the right stuff, it is no surprise that they find them in emergency medicine.

Dan Buckland earned his PhD from MIT in Aeronatuics and Astronautics, and is currently enrolled in Harvard Medical School. He’s also an Associate member of the Center for Space Medicine at Baylor College of Medicine, and an editor for Medgadget.com

References
1. Richard L. Summers, Smith L. Johnston, Thomas H. Marshburn, Dave R. Williams. Emergencies in Space. Annals of Emergency Medicine - August 2005 (Vol. 46, Issue 2, Pages 177-184, DOI: 10.1016/j.annemergmed.2005.02.010)



 

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