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Safe Passage: Astronaut Care for Exploration Missions Astronaut Charles Conrad, Jr., commander of the first manned Skylab mission, undergoing a dental examination by Medical Officer Joseph Kerwin, M.D., in the Skylab 2 Medical Facility during Earth orbit on June 22, 1973. In the absence of an examination chair, Conrad simply rotated his body to an upside down position to facilitate the procedure. NASA image.
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Safe Passage: Astronaut Care for Exploration Missions 3 Managing Risks to Astronaut Health We had to struggle a little bit, but we showed the reason that manned spaceflight has been as successful as it has for a large number of years. A large team of people scattered across the entire planet were able all together to get a major advance in the space station assembly operations. Chuck Shaw, lead flight mission director for the 100th shuttle mission commenting from Houston Mission Control on the successful attachment by the shuttle Discovery astronauts of the nine-ton Z1 structural truss to the International Space Station’s Unity module, October 14, 2000 Perhaps the most ambitious goal of the National Aeronautics and Space Administration’s (NASA’s) space medicine program is to be able to provide optimal health care to the first (and subsequent) astronauts who will go on exploration-class missions to Mars. Because any such mission lies more than a decade in the future, the challenge to the Institute of Medicine (IOM) Committee on Creating a Vision for Space Medicine During Travel Beyond Earth Orbit was this: what can usefully be said, so far in advance, about providing day-to-day health care in space, while on the Martian surface, and during the return trip to Earth? What types of illnesses and injuries might reasonably be anticipated on long-duration space missions?
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Safe Passage: Astronaut Care for Exploration Missions In this chapter, the committee tries to begin answering those questions by looking at the only evidence available: the morbidity and mortality experiences of U.S. astronauts and Russian cosmonauts, U.S. Navy submariners, and Australian scientists and explorers in the Antarctic. This look back includes findings from physical examinations conducted in space to see what is normal, or baseline, in microgravity. The committee also examines potential health problems in each of several medical practice areas—cardiology, neurology, surgery, and psychiatry, to name a few—in which critical risks have been identified (see Table 2–2). The committee anticipates that long-duration missions beyond Earth orbit will be qualitatively different from short spaceflights. Medical and behavioral issues that have not been particularly problematic on short flights may loom large on exploration-class missions. It is not possible to accurately predict the treatment innovations, technological advances, and shifting standards of care that may occur over the next 20 years and prove relevant to medical practice in space. GENERAL PRINCIPLES AND ISSUES The focus of this chapter is the care of the individual patient in space. Premission evaluation should include assessments of both the astronaut’s health status (including the status of specific organ systems at risk, such as the musculoskeletal system [see Chapter 2 for the risks involved]) and other risks. The general principles of care are the maintenance of normal health status in microgravity and, if illness or injury occurs, restoration of normal function as quickly and efficiently as possible during and upon the return from the space mission. As part of a responsible space crew, each crewmember should be expected to participate in routine surveillance to be able to measure the health status of other members of the crew at regular intervals. Resources should be available for the diagnosis and treatment of the most common minor and major illnesses and injuries that are anticipated to occur in the Earth environment, as well as to diagnose and treat conditions that are unique to microgravity and the particular space mission. The crew should be prepared to treat a wide variety of conditions of various degrees of severity during a space mission and, most of all, be prepared to treat the unexpected. The major health and medical issues related to exploration-class missions have been of little risk or concern to NASA up to the present for short-duration space travel (e.g., space transportation system [STS] space shuttle missions) (Box 3–1). All of the major health and medical issues are pro-
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Safe Passage: Astronaut Care for Exploration Missions jected, however, to be moderate to severe concerns that affect astronaut health on the International Space Station (ISS), and except for radiation protection and bone mineral density loss, the degree of severity of the other health and safety challenges have yet to be estimated for exploration-class missions. Many of these issues and challenges are directly related to or are completely tied to known human physiological adaptations to space travel. Separation of these issues from the discussions of physiological adaptations in Chapter 2 is in many cases artificial. Similar concerns, issues, and topics on medical, surgical, rehabilitative, and behavioral health in this chapter and in Chapters 4 and 5 must also be considered in the continuum of clinical research and health care for astronauts to begin building the infrastructure and health care system (Chapter 7) needed for human exploration of deep space. The committee has chosen to separate these topics into chapters to place the emphasis on clinical research (Chapters 2 to 5), health care (Chapters 3 to 5), and opportunities and ethical and infrastructure concerns (Chapters 6 and 7) that it believes is necessary to promote the needed attention to the safe passage and the health of astronauts during travel beyond Earth orbit and into deep space. BOX 3–1 Major Health and Medical Issues During Spaceflight Health or Medical Issue GRD AIR STS ISS EXP Radiation protection G G G Y R Hearing conservation G G G R TBD Cardiovascular G G G Y TBD Muscle G G G Y TBD Bone loss G G G Y TBD Neurovestibular Y NA G R TBD Habitability NA G Y Y TBD Extravehicular activity risk NA G Y Y TBD Medical care Y NA Y Y TBD Diversity (age, gender, etc.) Y NA Y Y TBD Psychological issues Y G G Y TBD Workers’ compensation Y G G Y TBD Abbreviations: GRD, ground; AIR, airflight; STS, space shuttle; ISS, International Space Station; EXP, exploration-class mission; G, green, little or no risk; Y, yellow, moderate risk; R, red, severe risk; TBD, to be determined; NA, not applicable. Source: Williams, 2000.
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Safe Passage: Astronaut Care for Exploration Missions Medical Events in Extreme Environments Evidence Base from Previous Space Missions A review of 79 U.S. space missions involving 219 person-flights lasting 2 to 17 days each (Putcha et al., 1999) reported that the most common conditions experienced were space motion sickness (SMS), nasal congestion, and sleep disorders. None of these medical conditions have required the mission to end, have been life threatening, or have required intensive medical treatment; they are bothersome but are not medical emergencies. Exploration-class missions, however, because of their lengths of as many as 3 years beyond Earth orbit, raise in NASA’s current judgment the probability of a major medical event, a condition requiring intervention by a medical practitioner, during the mission (Billica, 2000). A study of 175 astronauts from 1959 to 1991 reported 20 deaths (19 males and 1 female), mostly unrelated to spaceflight because of high rates of automobile and aircraft accidents and accidental deaths on the Apollo 1 and the Challenger spacecrafts. The small numbers of participants and the premature deaths from injuries may well mask the morbidity and mortality figures from other disorders related to spaceflight, such as cancer, if the participants live long enough (Peterson et al., 1993). Related disorders such as the development of cancer and cardiovascular, arthritic, and other conditions may increase in frequency as the duration of space travel and the ages of astronauts increase, just as they would had the same individuals remained on Earth. The risks of medical events increase with the lengths of missions (Billica et al., 1996). A survey of the perception of risk from spaceflight was returned by 65 medical professionals and showed that medical events with the highest perceived likelihood of occurrence had the least effect on the mission or the crew, but those with the greatest impact on the mission or crew were least likely to occur (Billica et al., 1996). Skin disorders (irritation from fiberglass, contact dermatitis, rashes, and furuncles) were thought to be the most common, followed by respiratory and digestive disorders. NASA reported that 1,867 medical events occurred from 1981 to 1998 on space shuttle flights STS-1 to STS-89 (Billica, 2000). Among the population of 508 individuals on those flights, 498 reported a medical event or symptom other than SMS. The events, derived from a histogram presented to the committee (Billica, 2000), were ill-defined symptoms (n=788), respiratory events (n=83), symptoms related to nervous system or sensory organs (n=318), digestive disorders (n=163), symptoms related to skin or
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Safe Passage: Astronaut Care for Exploration Missions subcutaneous tissue (n=151), symptoms related to the musculoskeletal system (n=132), and injuries (n=141). Approximately 5 percent (77 of 1,777) were injuries, and 10 deaths occurred, 7 during a catastrophic explosion in the early phase of the launch (Challenger in 1986) and 3 from a fire on the launchpad (Apollo 1 in 1967). Rates of events have not been reported, and associations of illness or injury with extravehicular activity (EVA) also have not been reported. EVAs are associated with a high workload and are associated with a much higher risk of injury because of the momentum imparted to large masses during EVAs and the lengthy periods of work outside the spacecraft (Nicogossian et al., 1994). Even in the non-EVA microgravity environment, fractures are possible due to movement of cargo, which can easily “get away” once set in motion or if an individual pushes away from a wall too hard and experiences a bone-jarring hit on the opposite wall (Nicogossian et al., 1994). This is a good example of the importance of training to prevent medical injury. The microgravity environments of long-duration space missions will also be associated with overexertion, strains, and sprains, because backaches and effects from the physical demands of EVAs have been reported during shorter missions and require pharmacological treatment (Putcha et al., 1999). Backaches are not specifically associated with EVAs but are a common complaint thought to be associated with elongation in vertebral column length and stress placed on intervertebral discs. This type of pain has been reported to be ameliorated by axial compression performed by crewmembers while in orbit (NASA, 2000b). The medications administered as a single dose or taken by only one person during 219 space missions have included phenazopyridine, omeprazole, zolpidem, sucralfate, an antifungal (Vagisil), clotrimazole (Mycelex), docusate, an antacid (Gaviscon), cimeditine, diclofenac, meclizine, ofloxacin, gentamicin, lovastatin, flavoxate, ketoprofen, metaxalone, and cephalexin. This spectrum of medications that has been taken and the disorders that have been treated on short missions point to the need to plan for a broad-based and space medicine-focused pharmacopoeia to treat a wide variety of signs, symptoms, and diseases on longer missions. The existence of such a pharmacopoeia also necessitates procedures to avoid potential abuse. It would have been helpful to the committee’s assessment if the data on illness and injury with and without an association with EVA made available to the committee had been stratified and publicly reported to allow the committee and others to have a better understanding of the health-related risks
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Safe Passage: Astronaut Care for Exploration Missions of spaceflight. Moreover, a number of questions remain unanswered. In addition, facts needed to best appreciate any list of health-related risks of spaceflight (Tables 3–1, 3–2, 3–3, and 3–4) to plan for future space missions were not available. For instance, (1) how were the symptoms distributed among astronauts with different specialties (e.g., pilots versus payload specialists)? (2) did astronauts who flew more than one mission experience fewer symptoms on subsequent flights? and (3) what was the degree of severity of the reported symptoms? It is therefore important to look at the totality of the data from space missions and what has been learned from other extreme isolated environments on Earth (e.g., Antarctica and extended underwater submarine missions). These data relate to the type and incidence of medical-surgical and behavioral health events that occur in these environments and are needed to best gauge and plan for future needs during extended space travel before commencement of exploration-class space missions with astronaut crews. Evidence Base from Extended-Duration Submarine Missions Medical events during submarine missions are instructive as they occur in a confined, remote environment where there is limited diagnostic and therapeutic support. They occur in an atmosphere where potentially life-threatening or other severe medical illnesses can end a mission, in the sense that the submarine is required to interrupt or even abort its mission. The U.S. Navy described the incidence of illnesses and injuries on 136 submarine patrols from January 1, 1997, through December 31, 1998. The numbers of acute encounters were related to the total number of person-days under way, with 2,044 acute encounters in 1.3 million person-days at sea, or 157 acute encounters per 100,000 person-days (Table 3–5). Stratified by illness and injury, illness accounted for 112.9 episodes per 100,000 person-days, with 70 percent able to maintain full duty; and accidents accounted for 37.2 episodes/100,000 person-days, with 55 percent able to maintain full duty (Thomas et al., 2000). A different perspective is obtained when the health disorders and medical-surgical procedures in Table 3–5 are compared with the reasons for medical evacuations from U.S. submarines (Table 3–6). A range of 1.9 to 2.3 medical evacuations per 1,000 person-months was reported for all submarines in the U.S. Atlantic Fleet from 1993 to 1996. A range of 1.8 to 2.6 evacuations per 1,000 person-months was reported for humane reasons (i.e., death or serious illness in the family) (Sack, 1998), suggesting that if these
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Safe Passage: Astronaut Care for Exploration Missions TABLE 3–1 In-Flight Medical Events for U.S. Astronauts During the Space Shuttle Program (STS-1 through STS-89, April 1981 to January 1998) Medical Event or System by ICD-9a Category Number Percent Incidence/14 days Space adaptation syndrome 788 42.2 2.48 Nervous system and sense organs 318 17.0 1.00 Digestive system 163 8.7 0.52 Skin and subcutaneous tissue 151 8.1 0.48 Injuries or trauma 141 7.6 0.44 Musculoskeletal system and connective tissue 132 7.1 0.42 Respiratory system 83 4.4 0.26 Behavioral signs and symptoms 34 1.8 0.11 Infectious diseases 26 1.4 0.08 Genitourinary system 23 1.2 0.07 Circulatory system 6 0.3 0.02 Endocrine, nutritional, metabolic, and immunity disorders 2 0.1 0.01 aInternational Classification of Diseases, 9th edition. SOURCE: Billica, 2000. data are extrapolated to extended space travel or habitation, the psychosocial support needs may well be just as important as the medical needs in a long-duration space mission. The medical reasons for submarine evacuations from 1993 to 1996 varied (Table 3–6). The largest number of conditions requiring medical evacuation are trauma and “other” (miscellaneous). It should be noted, however, that psychiatric reasons rank second in the specific categories. The “other” category most likely consists of large numbers of unrelated clinical conditions, further reinforcing the diversity of clinical conditions that can be expected to occur during a space mission. Factors such as astronaut age and medical prescreening would affect the incidence of medical emergencies among the members of the space crew, but since prescreening for most conditions cannot be done, it is possible that similar disorders and the proportions of those disorders that could occur among the members of a space crew would be similar to those that occur among individuals on submarine missions.
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Safe Passage: Astronaut Care for Exploration Missions TABLE 3–2 Medical Events Among Seven NASA Astronauts on Mir, March 14, 1995, through June 12, 1998 Event Number of Events Incidence/100 Days Musculoskeletal 7 0.74 Skin 6 0.63 Nasal congestion, irritation 4 0.42 Bruise 2 0.21 Eyes 2 0.21 Gastrointestinal 2 0.21 Psychiatric 2 0.21 Hemorrhoids 1 0.11 Headaches 1 0.11 Sleep disorders 1 0.11 NOTE: Data from the Russian Space Agency reports that there were 304 in-flight medical events onboard the Mir from February 7, 1987, through February 28, 1998. The numbers of astronauts at risk or the incidence per 100 days was not reported. SOURCE: Marshburn, 2000b. Tansey and colleagues (1979) reviewed health data from 885 Polaris submarine patrols from 1963 to 1973, for 4,410,000 person-days of submarine activity. They described 1,685 medical events that resulted in 6,460 duty days lost. Only events that resulted in the loss of at least 1 workday were reported. The events with the six highest rates of occurrence were, in descending order, trauma, gastrointestinal disease, respiratory infections, dermal disorders, infection, and genitourinary disorders. The spectrum of disorders was very broad and included cases of arrhythmia, paroxysmal superventricular tachycardia, infectious hepatitis, gastrointestinal hemorrhage, meningococcemia, paranoid schizophrenia, appendicitis, pilonidal abscess, perirectal abscess, ureteral calculi, testicular torsion, and crush injuries, further emphasizing that the scope of anticipated medical conditions on long-duration space missions will be very broad (Tansey et al., 1979). The incidence of the types of illnesses observed during extended submarine missions is generally similar to the incidence encountered during spaceflights. NASA has used the incidence of medical events on submarines to estimate that there may be one major medical event requiring intervention of the type usually delivered by a medical practitioner during a future exploration-class mission of 3 years in length with five to seven astronauts (Billica, 2000; Flynn and Holland, 2000). Unfortunately, the nature of that
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Safe Passage: Astronaut Care for Exploration Missions TABLE 3–3 Medical Events and Recurrences Among Astronauts of All Nationalities on Mir, March 14, 1995, through June 12, 1998 Event Number of Events Recurrences Superficial injury 43 2 Arrhythmia 32 98a Musculoskeletal 29 NRb Headache 17 8 Sleeplessness 13 9 Fatigue 17 4 Contact dermatitis 5 3 Surface burn 5 NR Conjunctivitis 4 2 Acute respiratory infection 3 NR Asthenia 3 2 Ocular foreign body 3 NR Globe contusion 2 NR Dental 2 NR Constipation 1 NR aSee Chapter 2. bNR, not reported. SOURCE: Marshburn, 2000b. NOTE: Further information on symptom duration, functional impact, or recurrences, especially the nature of arrhythmias and the number of astronauts who experienced them, is important for assessment of the potential impacts of such events on prolonged space missions. Other than arrhythmias, the medical events reported were minor, although most were certainly as vexing in space as they would be on Earth. event is unpredictable, so preparations must be prioritized and must still be made for a wide spectrum of problems. Evidence Base from Antarctic Expeditions The Australian National Antarctic Research Expeditions (ANARE) Health Register compiled 1,967 person-years of data from 1988 to 1997. It documents 5,103 illnesses and 3,910 injuries (Table 3–7). The distribution and variety are similar overall to those from spaceflight data. Seventeen Australians, moreover, have died in the Antarctic and subantarctic since 1947 (Taylor and Gormly, 1997; D.J.Lugg, ANARE, personal communication, August 24, 2000). Excluding those conditions peculiar to
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Safe Passage: Astronaut Care for Exploration Missions TABLE 3–4 Pharmacopoeia Usage During Mir Missions Medications Number of tablets or doses dispensed Pseudoephedrine 131 Zolpidem 81 Temazepam 68 Diphenhydramine 60 Aspirin 55 Acetaminophen 37 Bisacodyl 32 Ibuprofen 28 Terfenadine 18 Long-acting phenylpropanolamine 13 Nose drops (Neosynephrine) 9 SOURCE: Marshburn, 2000b. NOTE: This list reaffirms the discomforts experienced by crew of previous missions and suggests the probability that nasal congestion, sleep disorders, pain, and constipation will afflict the crews of longer-duration space missions. TABLE 3–5 Incidence of Health Disorders and Medical-Surgical Procedures During 136 Submarine Patrols Disorder Number/100,000 Person-Days Injury (includes accidents) 48.8 Respiratory 24.6 Skin or soft tissue 19.0 Ill-defined symptoms 10.5 Infections 10.0 Procedure Percentage of All Procedures Performed Wound care, splinting 42.0 Suturing 18.7 Cleansing 8.2 Nail removal 6.8 Fluorescein eye examination 4.2 Incision and drainage of abscess 2.9 Tooth restoration 2.0 SOURCE: Thomas et al., 2000.
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Safe Passage: Astronaut Care for Exploration Missions Hematology, Immunology, and Microbiology Decreased red blood cell mass during space missions has been recognized since 1977 (Johnson et al., 1977; Leach and Johnson, 1984), but there is no resulting impairment from this “anemia.” The documented fall in erythropoietin levels and the fall in the numbers of reticulocytes indicate that this results from diminished production, not increased cellular destruction (Alfrey et al., 1996). However, because of the diminution of the plasma volume early in the flight, the measured hematocrit levels and red blood cell counts did not fall during flight but were noted after the return to Earth because of the more rapid restoration of plasma volume than the level of red blood cell production. Erythropoietin levels returned to normal in 1 to 2 weeks after landing. In 1990, Koury and Bondurant (1990) hypothesized that erythropoietin prevents programmed cell death in erythropoid progenitor cells, thereby adding significantly to general medical knowledge through research conducted in space. Anemia could become a clinical problem during long-duration space travel, and erythropoietin administration is being evaluated as a countermeasure. Altered cell-mediated immunity has been reported in a variety of analog environments, including the Antarctic (Tingate et al., 1997) and space (Kimzey et al., 1975, 1977). Escherichia coli and Staphylococcus aureus isolates have also been shown to become more resistant to selected antibiotics during space travel (Lapchine et al., 1986). Although the clinical significance of these alterations has not been determined, the effects on skin and wound infections and wound healing during long-duration space missions could become clinically important. Preflight isolation techniques for spaceflight crewmembers are reported to have decreased the infection rate for the 3 weeks preflight from about 50 percent to only occasional events (Ferguson, 1977; Ferguson et al., 1977). Gingivitis and skin furuncles are now the primary preflight infections reported (Taylor and Gormly, 1997). Increased shedding of herpesvirus and expansion of Epstein-Barr virus-infected B cells have been reported in the Antarctic environment (Tingate et al., 1997; Lugg and Shepanek, 1999) and in astronauts (Payne et al., 1999). The bases for the divergent changes are not understood. They do, however, indicate the importance of immunology and microbiology to healthy human physiology during space travel and the need for further research in this area of space medicine.
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Safe Passage: Astronaut Care for Exploration Missions Health Care Opportunity 12. Performing clinical studies on anemia, immunity, wound infection, and wound healing as part of every space mission. Mental Health Issues The transition to long-duration space missions will require greater emphasis on ways to prevent and successfully manage an array of challenges to the cognitive capacities and emotional stabilities of astronauts who will find themselves in an isolated, confined, and hazardous environment. They will be devoid of much of what supports their emotional well-being on Earth and will need to develop and maintain new coping strategies appropriate to the unique environment of space beyond Earth orbit. Current data on the psychiatric sequelae of long stays in surly environments come primarily from studies of military personnel on submarine duty, Antarctic field scientists, and Biosphere inhabitants (Billica, 2000), as well as more limited experience on the Russian space station Mir. These data suggest that the incidence of discernible psychiatric symptomatologies, including depression, anxiety, substance abuse, and psychosis, ranges from 3 to 13 percent per person per year, depending on the setting (see Tables 3–2 to 3–7). Transposed to a six- or seven-member space crew on a 3-year mission, the likelihood that psychiatric problems will arise on such an expedition is not insignificant but is less than 54 percent—(3 percent/year)×(six astronauts/year)×(a 3-year mission)—per astronaut during a 3-year mission among a space crew when one extrapolates from the crude available data on behavioral disturbances in space. Such problems can range from simple boredom and fatigue to acute stress reactions, profound depression, and overt psychosis. Some mental health problems may become more likely over time as the cumulative effects of environmental and interpersonal stressors are magnified by the extended duration of the mission. The NASA Experience to Date Almost all of NASA’s behavioral medicine experience with space travelers thus far has been with flights of relatively short duration (i.e., 2 to 3 weeks), where emergent signs and symptoms have included evidence of stress, anxiety, diminished concentration, depressed mood, malaise, and fatigue. These problems have been identified in less than 2 percent of astronauts, and their effects on individual and crew performance have reportedly
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Safe Passage: Astronaut Care for Exploration Missions been negligible (Flynn and Holland, 2000). As a result, with the exception of the astronaut selection process, the level of clinical and research interest in mental health problems that may affect human performance during space missions has been relatively low. At the same time, there is growing awareness that such problems could prove to be major impediments to the successful conduct of longer-duration missions. Mental Health Aspects of Extended-Duration Spaceflight Little is known about the psychological capacity of humans to withstand the stresses of long-duration space travel, but what is known (e.g., from the experience on Mir) is ominous. Experience with extended-duration flights, defined as flights longer than 100 days (about 1/10 the anticipated duration of a mission to Mars), suggests that boredom, fatigue, and circadian rhythm and sleep disturbances, coupled with the exacting human performance requirements of such missions, constitute risk factors for the development of depressive syndromes of various severities, anxiety and irritability, and at times, dysfunctional interpersonal relationships, either within the spacecraft or between astronauts and ground personnel. On missions beyond Earth orbit, in which spacecraft crews will be isolated and confined to a relatively small living space and in which medical evacuation will not be an option, the development of these and other mental health problems may exert cumulative detrimental effects both on individual astronauts and on their fellow crewmembers sufficient to jeopardize the mission. Meeting this challenge will require a reassessment of the mental health needs of astronauts in the context of NASA’s overall health care program. Areas of renewed emphasis and support should include premission psychiatric evaluation; intramission psychiatric support and treatment, including the possibility that acute interventions may be required, such as in a major psychotic break, possibly with the use of forcible restraint and psychoactive drugs; and a program of postmission assessment, follow-up, and intervention where appropriate, as discussed in Chapter 5. For international efforts involving multinational crews, language and cultural differences, along with different approaches to diagnosis and treatment, will complicate these tasks. Accordingly, the United States and its partners in space must move toward the development of a health care system for astronauts (see Chapter 7) with a common language, common diagnostic criteria, and common standards of care. In so doing, some suggested areas of emphasis (see also Chapter 5) are as defined below.
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Safe Passage: Astronaut Care for Exploration Missions Health Care Opportunity 13. Developing methods for the identification and management of mood disorders and suicidal or homicidal ideation and developing protocols for the management of violent behavior, including crisis intervention, pharmacological restraint, and physical restraint. Premission Screening and Selection The issue of crew selection needs to be rethought in the context of longduration space missions. As detailed in Chapter 5, valid and reliable psychiatric screening instruments should be further developed, tested, and refined. The process of astronaut selection into or out of the program must include efforts to predict crewmembers’ responses to the anticipated stresses of long-duration space missions on the basis of data derived from studies carried out on the ISS as well as in analog environments. Assessment of interpersonal, leadership, and followership skills, problem-solving capabilities, and emotional stability under conditions of extended isolation are some of the areas appropriate for future research. In addition, personal and family history data coupled with laboratory testing may identify individuals at increased risk for mental disorders (e.g., depression) that may emerge over the course of long-duration space travel and may be included in the database on which crew selection and flight assignments are based. The development of more sophisticated selection and deselection criteria is a first step, to be followed by specific individual and group training in behavioral self-assessment and the self-administration of countermeasures designed for a range of anticipated health problems. Training individuals to work successfully within a small group and to engage in productive and collaborative problem solving with ground crews should be part of this process. The relative value of such training and the efficiency of specific countermeasures should also be assessed in the context of a well-designed program of behavioral and psychosocial research. Such studies should be carried out in the course of extended stays in space and in appropriate simulated or analog environments. Finally, the selection and training of the members of ground crews who will support and direct long-duration missions should be parallel to and integrated with the selection and training of the astronauts. Dealing with Intramission Mental Health Problems As mental health problems arise, some will respond to countermeasures designed and tested during premission training, whereas others will require
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Safe Passage: Astronaut Care for Exploration Missions the intervention of crewmembers or ground personnel. In this context, there will need to be clearly defined duties and responsibilities for such personnel, as well as appropriate training. Evidence-based clinical protocols and treatment algorithms that are specifically adapted for the space environment will need to be developed and tested. In addition to the availability of psychiatric expertise on the ground, the preventive approach to in-mission mental health care should include the prior development of supportive and therapeutic relationships between mental health clinicians, crewmembers, and crewmember families. In this context, finding ways of ameliorating the effects of prolonged communication delays between space and the ground should be a research priority. An onboard formulary that anticipates the range of psychiatric problems that may or will arise is also essential, as is research on the pharmacokinetics of current and future psychotropic medications in microgravity environments. Technology offers promise for maintaining behavioral health when professional assistance is millions of miles away. One type of countermeasure is software designed to self-diagnose and relieve emotional symptoms before they become a psychiatric condition. The first of most famous of these was ELIZA (Weizenbaum, 1966, 1979). It mimicked a nondirective therapeutic dialogue. The second generation of algorithm-driven software packages is now available. One example is the Therapeutic Learning Program (Gould, 1989). Software-guided therapy, when coupled initially with individual training and clinical oversight, has produced relief of symptoms ranging from headaches to anxiety and depression. Although, for the most part, the gains are nowhere near those obtained from individual treatment, the benefits are far superior to no treatment at all. An excellent and balanced review of this subject is contained in Massachusetts Institute of Technology Professor Sherry Turkel’s book, Life on the Screen: Identity in the Age of the Internet (Turkel, 1995). It is likely that later versions of these methods will be far more effective and could be adapted, with adequate training and clinical oversight, for use by astronauts on long-duration missions. Postmission Mental Health Care Although acute and chronic in-mission psychiatric problems may jeopardize mission success, severe, postmission mental health problems, if directly attributable to astronauts’ participation in long-duration missions, could jeopardize the program itself. The NASA-sponsored longitudinal follow-up study of astronauts’ health has not revealed any untoward psychiatric sequelae of participation in the space program, although the stress of
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Safe Passage: Astronaut Care for Exploration Missions reintegration and postflight adjustment has been noted. The unpredictable effects of mission-related physiological changes and potential exposure to radiation, coupled with the emotional stress of reintegration following a long-duration mission, make it imperative that a postmission program of psychiatric assessment and individual, peer, and family support as well as mechanisms for long-term peer and family follow-up support be developed. Neurological Issues Nervous system dysfunction and illness may occur as a result of physiological adaptive responses (both neural and systemic) to microgravity, as a consequence of problems that arise within the spacecraft, or as a result of external events or exposures. In considering the neurological illnesses or events that might occur during a mission to deep space, the timing, type, and severity of problems should be taken into account. A logical medical distinction is to consider neurological problems that affect either the central nervous system or the peripheral nervous system, or both. This somewhat arbitrary distinction has practical implications from a diagnostic and therapeutic perspective. Available data indicate that a fairly high incidence of minor neurological complaints may occur (Tables 3–2 and 3–3). Contingencies are also needed for catastrophic neurological events, including those that threaten astronauts’ lives and the mission itself. NASA recognizes that the occurrence of certain severe life-threatening events can exceed the capacities of either the astronaut crew or ground control to intervene medically. This concept of acceptable risk may be different for a single one-time mission than for a multimission exploratory program. Acute Central Nervous System Illnesses or Events There are insufficient data on which to base sound estimates of either the incidence of various central nervous system problems or the extent to which various central nervous system problems might occur during a long-duration space mission. So far, no major neurological illnesses have been reported. However, reports from the U.S. and Russian manned space missions suggest that minor neurological problems are frequently encountered (Tables 3–2 and 3–3). These include headache and vestibular dysfunction, particularly upon the initial entry into microgravity. A serious problem upon the return to Earth is orthostasis, with its consequent effects on many bodily systems including the central nervous system.
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Safe Passage: Astronaut Care for Exploration Missions Closed head injuries and spinal cord injuries are among the most serious neurological events that could occur during travel beyond Earth orbit. Management and treatment of individuals with severe closed head injuries would likely be beyond the capability of an astronaut crew unless dramatic new approaches to clinical management are developed. Thus, injuries that produce very low Glasgow coma scales by today’s standards will probably result in death, as they frequently do under the best of circumstances in current state-of-the-art medical centers. However, consideration should be given to training in the management of individuals with less severe closed head injuries. Individuals with mild or moderate closed head injuries may survive but remain disabled because of residual neurological deficits. Management issues today include placement of burr holes for evacuation of subdural hematomas, feeding and airway control, spinal cord stabilization, and management of bowel and bladder functions and infections. Other events to consider include toxic exposures, decompression sickness (especially in connection with EVAs), cerebrovascular-like events, spinal injuries, exposure to radiation, and seizures. The current neurological clinical research program at NASA, although extensive, does not appear to be well coordinated among the various research organizations and those that design and conduct flight operations. Detailed treatment contingencies based on the accumulated evidence base for the entire spectrum of neurological diseases should be developed. Such treatments should be continuously reviewed and updated to maintain state-of-the-art readiness. Health Care Opportunity 14. Establishing a coordinated clinical research program that addresses the issues of neurological safety and care for astronauts during long-duration missions beyond Earth orbit. Urinary Disorders Genitourinary disease may present as an infection, obstruction, or malignancy. Many potential genitourinary problems will be identified through standard screening. Renal stone formation (expected in 0 to 5 percent of astronauts) secondary to bone calcium mobilization and excretion in the urine is a well-identified concern in microgravity environments. The genitourinary effects of microgravity also include changes in urodynamics (unknown incidence) and urinary hesitancy (reported seven times). Nephrolithiasis is a concern during extended stays in microgravity, as alterations in calcium metabolism and hydration status have previously been identified in
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Safe Passage: Astronaut Care for Exploration Missions this environment. Dehydration (incidence, 0.01 per 14 days on the space shuttle) is a recognized problem (Lane and Schoeller, 2000). Dehydration or significant changes in pH and increases in calcium and citrate levels increase the risk of renal stone formation. Preflight screening should include appropriate ultrasound evaluation for nephrolithiasis. Urinary tract infections are common (and are more common in females) and are generally easy to treat with antibiotics. Prostatitis can be treated with antibiotics. Preflight screening for prostate cancer by determination of the prostate-specific antigen level in serum and other evaluations, according to today’s standards, appears to be adequate, although future consideration may be given to preflight ultrasound or other developing noninvasive methods. Countermeasures for genitourinary problems are primarily oriented toward the prevention of nephrolithiasis through adequate hydration. The recommended daily fluid intake is greater than 2.5 liters. A more than adequate water supply must be ensured so that crewmembers do not hesitate to drink adequate volumes of water to prevent the formation of renal calculi. As ultrasound devices become smaller, it is likely that an ultrasound device will be standard medical equipment for all long-duration space missions. This would make it possible and desirable to perform in-mission screening for nephrolithiasis (to identify those who require medication or increased levels of hydration to treat calculi). As countermeasures are developed for the problem of bone mineral density loss in microgravity, it must be ensured that the solutions do not result in increased rates of renal stone formation secondary to alterations in calcium metabolism. Some of the health care opportunities that may be explored to increase the future effectiveness of managing risks to astronaut health during space travel have been described in this chapter and are listed in Box 3–6. This is a short list of current opportunities. It is neither a comprehensive list nor a list of priorities but is presented as a list of areas of research and development to be considered. New opportunities, including some that may take precedence, will develop in the future as the field of space medicine continues to evolve. CONCLUSION AND RECOMMENDATION Conclusion Space travel is inherently hazardous. The risks to human health of longduration missions beyond Earth orbit, if not solved, represent the great-
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Safe Passage: Astronaut Care for Exploration Missions BOX 3–6 Health Care Opportunities in Space Medicine Expanding, validating, and standardizing a modified physical examination, the microgravity examination technique, and including a technique for pelvic examination for use in microgravity. Developing an easily accessible database for medications on the spacecraft, including dosage, indications, adverse effects, and anticipated changes in the pharmacokinetic profile in microgravity. Developing an easily accessible hazardous materials manual for space travel to aid in the surveillance, detection, decontamination, and treatment of chemical exposures. Monitoring and quantifying particulates on a continuing basis. Examining the capability of microbial identification, control, and treatment during space travel. Developing methods for noise cancellation or reduction. Standardizing ergonomic practices on the basis of the human body’s response to the microgravity environment. Developing methods to measure human solar and cosmic radiation exposures and the means to prevent or mitigate their effects. Providing a thorough cardiovascular evaluation similar to the premission evaluation at the cessation of space travel to provide useful data as part of the continuum of astronaut care and to aid in establishing an evidence base for cardiovascular disorders during space travel. Developing a program for instruction in basic dental prophylaxis, the treatment of common dental emergencies such as gingivitis, tooth fracture, dental trauma, caries, and dental abscesses; and tooth extractions. Studying the bioavailability and pharmacological function of exogenous hormone therapy during space travel and, as new medical therapies for gynecological surgical conditions evolve, testing of these therapies for use during space travel. Performing clinical studies on anemia, immunity, wound infection, and wound healing as part of every space mission. Developing methods for the identification and management of mood disorders and suicidal or homicidal ideation and developing protocols for the management of violent behavior, including crisis intervention, pharmacological restraint, and physical restraint. Establishing a coordinated clinical research program that addresses the issues of neurological safety and care for astronauts during long-duration missions beyond Earth orbit.
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Safe Passage: Astronaut Care for Exploration Missions est challenge to human exploration of deep space. The development of solutions is complicated by lack of a full understanding of the nature of the risks and their fundamental causes. The unique environment of deep space presents challenges that are both qualitatively and quantitatively different from those encountered in Earth orbit. Risks are compounded by the impossibility of a timely return to Earth and of easy resupply and by the greatly altered communications with Earth. The success of short-duration missions may have led to misunderstanding of the true risks of space travel by the public. Public understanding is necessary both for support of long-duration missions and in the event of catastrophe. Recommendation NASA should give increased priority to understanding, mitigating, and communicating to the public the health risks of long-duration missions beyond Earth orbit. The process of understanding and mitigating health risks should be open and shared with the national and international general biomedical and health care research communities. The benefits and risks—including the possibility of catastrophic illness and death—of exploratory missions should be communicated clearly, both to astronauts and to the public.
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Safe Passage: Astronaut Care for Exploration Missions NOTES
Representative terms from entire chapter: