Jeffrey R. Davis

Comparison of treatment strategies for space motion sickness

Treatment strategies for Space Motion Sickness were compared using the results of postflight oral debriefings. Standardized questionnaires were administered to all crewmembers immediately following Space Shuttle flights by NASA flight surgeons. Cases of Space Motion Sickness were graded as mild, moderate or severe based on published criteria, and medication effectiveness was judged based on subjective reports of symptom relief. Since October 1989, medication effectiveness is reported inflight through Private Medical Conferences with the crew. A symptom matrix was analyzed for 19 crewmembers treated with an oral combination of scopolamine and dextroamphetamine (scopdex) and 15 crewmembers treated with promethazine delivered by intramuscular (IM) or suppository routes. Scopdex has been given preflight as prophaxis for Space Motion Sickness but analysis showed delayed symptom presentation in 9 crewmembers or failed to prevent symptoms in 7. Only three crewmembers who took scopdex had no symptoms inflight. Fourteen out of 15 crewmembers treated with IM promethazine and 6 of 8 treated with promethazine suppositories after symptom development had immediate (within 12 h) symptom relief and required no additional medication. There were no cases of delayed symptom presentation in the crewmembers treated with promethazine. This response is in contrast to untreated crewmembers who typically have slow symptom resolution over 72-96 h. We conclude that promethazine is an effective treatment of Space Motion Sickness symptoms inflight. NASA policy currently recommends treating crewmembers with Space Motion Sickness after symptom development, and no longer recommends prophylaxis with scopdex due to delayed symptom development and apparent variable absorption of oral medications during early flight days.

Clinical risk management approach for long-duration space missions.

INTRODUCTION In the process of crewmember evaluation and certification for long-duration orbital missions, the International Space Station (ISS) Multilateral Space Medicine Board (MSMB) encounters a surprisingly wide spectrum of clinical problems. Some of these conditions are identified within the ISS Medical Standards as requiring special consideration, or as falling outside the consensus Medical Standards promulgated for the ISS program. METHODS To assess the suitability for long-duration missions on ISS for individuals with medical problems that fall outside of standards or are otherwise of significant concern, the MSMB has developed a risk matrix approach to assess the risks to the individual, the mission, and the program. The goal of this risk assessment is to provide a more objective, evidence- and risk-based approach for aeromedical disposition. Using a 4 x 4 risk matrix, the probability of an event is plotted against the potential impact. Event probability is derived from a detailed review of clinical and aerospace literature, and based on the best available evidence. The event impact (consequences) is assessed and assigned within the matrix. RESULTS The result has been a refinement of MSMB case assessment based on evidence-based data incorporated into a risk stratification process. This has encouraged an objective assessment of risk and, in some cases, has resulted in recertification of crewmembers with medical conditions which hitherto would likely have been disqualifying. CONCLUSIONS This paper describes a risk matrix approach developed for MSMB disposition decisions. Such an approach promotes objective, evidence-based decision-making and is broadly applicable within the aerospace medicine community.

Strategies for the preflight circadian shifting of Space Shuttle crews.

In June, 1990, a workshop was put together at NASA/Johnson Space Center to address difficulties the astronauts were having in adjusting their wake and sleep schedule, both immediately before and during Space Shuttle missions. The workshop members, prominent investigators in human circadian research, developed a number of strategies by which astronauts could tackle the problem of circadian adaptation within the demanding timetable of a Space Shuttle mission. The strategies included both abrupt and gradual methods, and some approaches used artificial “very bright lights” to reset the physiologic circadian pacemaker. The strategies have since been operationally implemented on Space Shuttle flights, with good success. This is a report of the problems addressed by the workshop and its recommendations.

The Human System and Spiral Development

Crew health and safety for exploration missions requires a comprehensive approach that involves health care policy and standard setting, developing specific program requirements, and research and technology development. Effective integration of these elements requires considering the human as a system much like other key launch, spacecraft and habitat systems for exploration. A Human System Working group (HSWG) was initiated at NASA Headquarters in November 2004 to bring all of the required human system elements together, including members from Space Operations and Exploration Systems Mission Directorates and the Office of the Chief Health and Medical Officer. The human system must address numerous challenges to humans traveling out of low Earth orbit for extended durations. These challenges include exposure to ionizing and non-ionizing radiation, maintaining behavioral health and performance, physiological changes from extended exposure to microgravity, provision of medical care and a safe environment (including radiation protection), solving human factors and habitability issues, and conducting frequent operational extravehicular activity (EVA). The HSWG will coordinate solutions to these challenges through recommended draft standards and requirements, coordination of program plans and budgets, and monitoring progress toward the goals for each exploration spiral.