Emergencies in Space

THE PRACTICE OF EMERGENCY MEDICINE/CONCEPTS Emergencies in Space Richard L. Summers, MD From the Department of Emergency Medicine, University of Mississippi Medical Center, Smith L. Johnston, MD Jackson, MS (Summers); and Medical Operations, Office of Space Medicine, (Johnston, Thomas H. Marshburn, MD Marshburn) and Astronaut Office (Williams), National Aeronautics and Space Administration, Lyndon B. Johnson Space Center, Houston, TX. Dave R. Williams, MD Manned spaceflight is inherently risky and results in unique problems from a trauma and medical perspective. Emergency care under these special physiologic and environmental conditions calls for novel techniques for diagnosis and therapy. [Ann Emerg Med. 2005;46:177-184.] 0196-0644/$-see front matter Copyright ª 2005 by the American College of Emergency Physicians. doi:10.1016/j.annemergmed.2005.02.010 INTRODUCTION traditional emergency medical principles could be applied for Despite the immense technological feats associated with rescue, injury evaluation, and acute treatment. However, there human extraterrestrial travel, there is always the potential need have also been in-flight incidents, including fires, vehicular for emergency medical attention. Historically, the difficulties collisions, and loss of environmental controls. These problems associated with illness and injury have accounted for the failures represent primarily technical glitches in which the resultant of more expeditions on Earth’s frontiers than any other single medical complications could have required emergency technical or environmental reason.1 It is reasonable to believe management. Because these events happened while the the same would also be true for the exploration of space. vehicle was still in orbit, the emergency approach required In space, as in most remote inhabitations, most medical consideration of the conditions of microgravity, the remote problems are manageable locally until definitive diagnosis and environment, and the limitation of resources. While reviewing treatment are available. However, when the problem is an the history of space medical urgencies and emergencies, one emergency and the closest medical facility is thousands of miles must remember that the direction of space exploration is away, then there are significant risks of an adverse outcome. constantly changing, and different and unforeseen emergencies Evacuation from space is costly and arduous and may not be could also arise. possible in a timely manner. Fortunately, astronaut selection, medical screening, and the short duration of most missions have Risk of an Emergency made medical emergencies rare. As space exploration progresses To date, the majority of space exploration has involved to longer missions, interplanetary travel, and possible extrater- healthy young individuals (average age approximately 40 years; restrial colonization with diverse and older populations, the approximately 20% are female astronauts) who have undergone need for improved medical preparation will become increasingly intensive medical screening and remain in space for only short important. Providing emergency medical care to this group will periods. In considering longer missions with more diverse crews, undoubtedly be the most difficult obstacle in any operations such as the extended occupancy of the International Space and contingency planning. This article examines the current Station or a possible voyage to Mars, then it is increasingly state of emergency medical care for those exploring the frontier important to plan for a medical emergency. of space. Risk analysis is the first step in any medical contingency planning. Using actuarial data, it is possible to estimate the risk History of Emergencies During Space Flight of an emergency medical event during space flight.1-3 In the In more than 60 person-years of manned spaceflight general population, the emergency incidence rate is usually involving more than 400 astronauts and cosmonauts, there have considered to be about 0.06 events per person-year. If a been only 21 fatalities from 5 events.1 However, there have been 7-member crew were to travel for 2.4 years to Mars (the multiple near catastrophes. Most mishaps that involved injuries approximate expected duration of such a trip), then we could have occurred during liftoff or reentry and include near expect 0.06 events per person-yearÂ7 personsÂ2.4 years=1.0 drownings, cabin decompression, and blunt trauma. In one emergency. incident, after landing 1,200 miles off target in 5 feet of snow, a This finding is consistent with the analysis from the cosmonaut of the Russian Voskhod 2 was attacked by wolves Longitudinal Study of Astronaut Health and data from the when he tried to exit the spacecraft. Because these medical Russian Space Program.4 Although this calculation may be events were all essentially ground-based accidents, the reasonable for estimating risk during future space travel when Volume 46, no. 2 : August 2005 Annals of Emergency Medicine 177 Emergencies in Space Summers et al the general population is involved, the current medical Trauma screening criteria for astronauts may make such a prediction Ophthalmology 1 unrealistic for routine mission planning. Second-degree burns 1 On examining evacuation rates for medical emergencies from Cardiopulmonary the Antarctic McMurdo Station, we can calculate an incidence Arrhythmias 2 of 0.036 events per person-year. The general crew health and Pneumonitis 4 the environment of isolation at such a station may reflect the Reactive airways 1 conditions faced by the astronauts, although the potential for an Internal Medicine emergency medical event may be somewhat different. In the Chronic headaches 1 Figure is a summary of all nonfatal severe medical events during Cellulitis of arm 1 spaceflight from 1961 to 1999 (total=17).1,2 In reviewing the Other unspecified 1 Genitourinary Figure, note the relative lack of trauma in the events recorded. Renal stone 1 This finding is in sharp contrast to the 48% trauma as a reason 1,2 Urinary retention 1 for evacuation from McMurdo Station. Prostatitis 1 A retrospective review of records from the National Urosepsis 2 Aeronautics and Space Administration (NASA) Johnson Space Center Longitudinal Study of Astronaut Health was conducted Figure. Summary of nonfatal spaceflight severe medical events in 1999 to estimate the occurrence, type, and severity of general (1961-1999), Total=17. illness in the astronaut population while they were not on active duty.4 Each event was classified according to medical signifi- cance, particularly with regard to whether it would have required emergency evacuation or could have been managed by prolonged space travel, the low afterload resistance and reduced the health maintenance facility planned for the International sympathetic outflow has been postulated to result in cardiac Space Station had the event occurred in flight.5 After subtrac- atrophy and loss of function.9 More recent evidence suggests tion of the events that were unlikely to occur in microgravity or that changes in ventricular volumes may be due to fluid would have been detected in preflight screening, an anticipated redistributions instead of atrophy.10 Despite an accentuation in medical evacuation incidence of 0.02 events per person-year was lung blood flow, there is no increase in alveolar fluid. Lung determined from the data. Using the onboard health mainte- volumes are changed with a 15% decrease in tidal volume and nance facility to treat less severe medical conditions would have an 18% decrease in alveolar and physiologic dead space. As a reduced the likelihood to 0.01 events per person-year for this result, there is small increase in the respiratory rate.7,8 During group of astronauts. This estimation is consistent with the prolonged exposure to microgravity, astronauts lose a small extensive data from the Russian program in which 3 percentage of total body calcium and bone density, which cosmonauts have been evacuated in 41.5 years of space flight results in an increase in urinary calcium.6-8 Muscles can also and in which the Mir Space Station had 1 medical evacuation in atrophy, with up to a 20% loss in strength and with associated 31 person-years.1,2 neuroplastic changes.6-8 There is also a decrease in lymphocyte numbers, with an increase in leukocytes but with a reduced Physiology and Pharmacology of Microgravity ability for phagocytosis.8,11 Circadian rhythms and sleep A microgravity environment results in such significant patterns are usually disrupted and can induce psychophysiologic physiologic changes that in the early years of space exploration, responses to stress.8,12 it was uncertain whether humans could even survive in space. More than 75% of all shuttle astronauts have taken some All physiologic and pharmacologic aberrations in response to form of medication for conditions typically considered microgravity should be considered when any therapeutic nonemergency (motion sickness, headache, sleeplessness, and responses to medical emergencies are contemplated during back pain) during their missions.13,14 Gastrointestinal motility spaceflight. appears to be significantly reduced during the first 72 hours of a On entering microgravity, there is an immediate shift of mission. Furthermore, space motion sickness symptoms, which dependent fluids cephalad, with a resulting diuresis and a include nausea and vomiting, may also affect drug absorption decrease in systemic plasma volume of 10% to 20% and a when drugs are taken orally. The changes in extracellular fluid transient

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