The Daily Dose • Monday, March 28, 2022
Space Medicine: The Final Frontier in Exponential Growth and Innovation
Modern space exploration is headed for exponential growth and innovation. Long-term missions to the moon and mars become more feasible with every advance in aerospace. Three accomplished aerospace physicians revealed the history of aerospace medicine, mission goals, major stressors faced by astronauts, and strategies to mitigate risks in the International Science Symposium, “Space Medicine” held on Saturday, March 19 at the IARS 2022 Annual Meeting. James P. Bagian, MD, PE, J.D. Polk, DO, MS, and Joan Saary, MD, PhD, possess a wealth of experience leading humanity’s exploration of the final frontier and shared rich clinical information on improving medical care in space and on earth during their session.
James P. Bagian, MD, PE, Professor, Anesthesiology, Industrial and Operations Engineering, Aerospace Engineering at the University of Michigan, provided an overview of aerospace medicine, describing its history, roles, tools and techniques, and stressors involved in this unique medical specialty. He outlined the goals of aerospace medicine as promoting the safety and effectiveness of humans exposed to the stressors of flight. The knowledge he shared during his presentation can be applied to the clinical and administrative aspects of anesthesia.
Aerospace medicine evolved from balloon aviation in 1783 with the French Montgolfier brothers. In the Late 19th century, Paul Bert, the French father of aerospace medicine, studied hypoxia and dysbarism in flight. By World War I and World War II, aviation progress accelerated from mere observation to tactical wartime goals, Dr. Bagian explained. He concluded his overview in present times.
Space flight research faces one major challenge: a small sample size. Access to in-flight study participants takes years, Dr. Bagian revealed. Ground-based and atmospheric research is often used as a surrogate.
Dr. Bagian described how crewmembers who undergo atmospheric and space flight face similar stressors. These include temperature, fatigue, circadian, cardiopulmonary, otovestibular, visual and cognitive stressors. The near weightlessness of space flight, however, adds problematic motion sickness, disequilibrium, musculoskeletal weakness, and hematologic disorders. Space motion sickness occurs in 75% of first-time astronauts due to either sensory conflict or fluid shift.
The most concerning spaceflight stressors are long-term vision changes caused by increased intracranial pressure, excessive radiation exposure, and the psychosocial stressors of living in confined quarters for months or years.
Reentry orthostatic hypotension is due to changes in vascular dynamics during extended space flight and eventual return to gravity. Intravascular fluid volume is equally dispersed on earth and shifts cephalad during spaceflight. Edema and diuresis occur during missions and astronauts return to earth approximately 1-2 liters depleted in volume. Additionally, the hemodynamic response of hypotensive tachycardia occurs after space flight. This is problematic on reentry and has led to the development of a g-suit to offset the hypotension with lack of cardiac response. Dr. Bagian made the correlation to patients on long-term bedrest where we see orthostatic hypotension.
He concluded that, as in healthcare, a systems-based approach is foundational to success. Clear goals, managed risk, and effective communication are needed for success in future exploration on long-term missions.
The next presenter J.D. Polk, DO, MS, Chief Health and Medical Officer at the National Aeronautics and Space Administration (NASA), discussed “How NASA Performs Medical Care Off the Planet,” describing how to prepare for space missions and mitigate risks. Before beginning his presentation, he reminded the audience that all his work is off label, as no FDA guidelines apply in space.
Most of NASA’s current medical work occurs in the International Space Station (ISS). The station is a 20-year, 26-country collaboration, travelling at 17,500 mph that communicates constantly with astronaut patients and physicians around the world.
He explained that upcoming lunar missions will be longer and occur more frequently, preparing for future missions to Mars. The newly developed SLS rocket is powerful enough to carry astronauts into deep space. It will make its inaugural launch this June and go back to the moon. Dr. Polk and colleagues are hopeful that the partial gravity of the moon and Mars will mitigate some of the stressors faced by astronauts during weightless space travel in the ISS.
Dr. Polk then delved into a specific type of space mission that NASA undertakes and the measures required to make it to launch. Design reference missions start with the specific mission in mind, then work in reverse to develop engineering, standards, and objectives to support that mission. Quality measures and standardization involve a continuous review process, clinical practice guidelines, quality reviews, checklists, and oversight. This allows measurement of where you have been, where you are, and where you are going.
The goal for a successful flight involves minimizing risks and NASA views these risks differently than in medicine. Dr. Polk describes a 5×5 table measuring frequency versus severity of an event. If the event is both frequent and severe it falls in the red zone and requires two reliable back-up systems. While preventive medicine is robust in space missions, certain conditions remain underpredicted.
Dr. Polk used the example of venous thromboembolism. Risk is increased from living in an enclosed environment. Carbon dioxide levels are ten times higher than earth, and astronauts experience fluid shifts and excessive radiation. NASA’s medical team attempts to minimize this risk by planning an evacuation strategy, available anticoagulation, and scrubbing carbon dioxide levels in the shuttle.
How does NASA predict medical needs on missions? NASA administration focuses on benchmarking, analogs, simulation, direct research, modified delphi and an integrated medical model. Modeling is performed using patient data (i.e. Antarctic exploration, deep-sea dives) from other disciplines that can be used to gather best practice information. Monte Carlo analysis uses this data to statistically generate the likelihood of specific illness occurring during space mission.
The ISS is currently involved in dynamic research including DNA sequencing, cardiac cell growth, studying Parkinson’s and different bacteria in orbit, vaccine production, and testing various pharmaceuticals. This exciting work offers unique clinical information that cannot be replicated on the ground and will help pave the way for the reality of future missions and life on Mars.
Joan Saary, MD, PhD, Director, Division of Occupational Medicine and Associate Professor, Department of Medicine, University of Toronto and Consultant to Royal Canadian Air Force and Canadian Forces Environmental Medicine Establishment and the Canadian Space Agency, described how far aerospace science will go here on the earth to research and train crewmembers in order to mitigate risk during space travel.
Risk mitigation is a crucial priority to every mission. Aerospace physicians have the additional challenge of keeping their patients well in hazardous environments. Mission design specifics are planned well before the details of the mission are fully known.
Medical data for specific hazards in space flight are derived from analogs. These analog missions are terrestrial sites that resemble the space environment in some aspect such as isolation, microgravity, decreased communication, or remote location. The lessons learned by solving problems in these analogs are applied for use in space missions.
Dr. Saary offered the Haughton Crater on Devon Island, a mountainous, Mars-like Arctic island spanning 21,331 sq. mi., with a 6,300-ft. ice caps and craters, in Canada as an example of one of these analogs. The terrain, extreme cold weather aircraft testing, extended daylight hours, and remote location, mimics the conditions of Mars. The 476-day British Trans-Arctic expedition in 1969 traversed the length of the Arctic Ocean’s icy surface that parallels space conditions. The four explorers survived this harsh terrestrial environment at the same time as the first moon landing.
The University of Bramen’s drop tower can produce 9 seconds of weightlessness for research. Parabolic flights use aircraft to provide 20 seconds of weightlessness. These flights allow crew in training to develop medical treatment that can function in weightless space.
Training analogs for spacewalk on earth involve a 280-pound space suit and a 23.5 million-liter, 40 foot-deep pool. The Medina Aquarius program off Key Largo on the ocean floor holds three-week long NASA missions for astronauts in training. They are confined to a small space and test technologies under different gravities.
Medical innovations for aerospace medicine include radioprotectants, precision medicine, and personal health monitoring technology. Dr. Saary tied in the principles of Moore’s law of exponential progress to current aerospace innovation. Growth in space exploration is on the horizon: we will see greater access to space travel, space stations, vehicles, and increased-duration space travel, Dr. Saary predicted. These opportunities will give us a better understanding about the human capacity to adapt. Dr. Saary emphasized our need to trust the science behind artificial intelligence.
To conclude her presentation, Dr. Saary referenced a quote from Lao Tzu, a 6th-century BC contemporary of Confucius in the Spring and Autumn period in Chinese history, “The journey of a thousand miles begins with one step.” She urged the audience to imagine, define, and participate in the future growth of space travel and medicine.