Handheld Sonographic Cardiovascular Imaging Under Hypergravity Conditions.

INTRODUCTION: Real-time cardiovascular imaging during hypergravity exposure has been historically limited by technological and physical challenges. Previous efforts at sonographic hypergravity imaging have used fixed ultrasound probes; the use of hand-held ultrasound, particularly performed by minimally trained laypersons, has been less explored. Here we will discuss handheld sonography to self-visualize carotid vascular and cardiac changes during hypergravity.METHODS: Three subjects with variable ultrasound experience ranging from no familiarity to extensive clinical experience used handheld ultrasound at rest and under stepwise +Gz hypergravity exposures (maximum +3.5 Gz) to visualize carotid vascular changes. Subxiphoid cardiac ultrasound was obtained by the most experienced subject. Subjects had variable prior hypergravity experience; all were trained in anti-G straining techniques. Sonographically inexperienced subjects underwent a brief (< 5 min) familiarization with the ultrasound probe, user interface, and desirable viewing window immediately prior to centrifugation; real-time coaching was provided. Ultrasound images were correlated to self-reported symptoms and hemodynamic data.RESULTS: Handheld ultrasound performed as desired; all subjects were successful at obtaining ultrasound images with adequate capture of windows of interest. Subxiphoid imaging efforts were limited by probe overheating and associated with variable quality of imaging due to probe displacement from straining techniques; the subject noted transient, mild discomfort and ecchymosis after imaging in the subxiphoid region.DISCUSSION: Even individuals with minimal or no ultrasound experience successfully obtained usable images under centrifuge conditions. While there were some limitations, this technical demonstration provides initial validation of handheld sonography as an available tool for real-time cardiovascular imaging in a hypergravity environment.Blue RS, Ong KM. Handheld sonographic cardiovascular imaging under hypergravity conditions. Aerosp Med Hum Perform. 2024; 95(3):158-164.

Centrifuge-Simulated Spaceflight After Aortic Valve Replacement and Atrial Septal Defect Repair.

INTRODUCTION: Human access to space is expanding rapidly in the commercial environment, with various private companies offering commercial flights to spaceflight participants (SFPs). SFPs are more likely than career astronauts to have medical conditions novel to spaceflight and may not have undergone as rigorous a medical screening process as that used for career astronauts, representing new and unstudied risks in the spaceflight environment. We report participation of a subject with recent median sternotomy for aortic valve replacement and atrial septal defect closure in centrifuge-simulated dynamic phases of orbital and suborbital spaceflight.CASE REPORT: A 40-yr-old man with a history of congenital bicuspid aortic valve and atrial septal defect with successful repair 8 mo prior participated in an ongoing human centrifuge research study. The subject had the opportunity to participate in up to five centrifuge runs in an 8-h period, with profiles simulating commercial spaceflight. Maximum exposures included +4.0 Gz, +4.5 Gx, 6.1 G resultant, and maximum onset rate < 0.5 Gz · s-1 and +1 Gx · s-1. Physiological data acquisition included hemodynamics, electrocardiogram, neurovestibular exams, and postrun questionnaires covering motion sickness, disorientation, and similar. The subject tolerated the physiological aspects of hypergravity well, noting progressive sternal pain with increasing +Gx, ultimately leading him to opt out of the final profile.DISCUSSION: Postcardiothoracic surgery risks to SFPs are largely unknown, especially within 12 mo of a significant surgical procedure. This case provides an approach for risk stratification, preparticipation evaluation, and medical management of a postsurgical patient with significant cardiac history in spaceflight and analog environments.Fernandez WL, Blue RS, Harrison MF, Powers W, Shah R, Auñón-Chancellor S. Centrifuge-simulated spaceflight after aortic valve replacement and atrial septal defect repair. Aerosp Med Hum Perform. 2024; 95(2):123-131.

Operational Considerations for Crew Fatality on the International Space Station.

BACKGROUND: While catastrophic spaceflight events resulting in crew loss have occurred, human spaceflight has never suffered an on-orbit fatality with survival of other crewmembers on board. Historical plans for management of an on-orbit fatality have included some consideration for forensic documentation and sample collection, human remains containment, and disposition of remains; however, such plans have not included granular detailing of crew or ground controller actions. The NASA Johnson Space Center Contingency Medical Operations Group, under authority from the Space and Occupational Medicine Branch, the Space Medicine Operations Division, and the Human Health and Performance Directorate, undertook the development of a comprehensive plan, including an integrated Mission Control Center response for flight control teams and Flight Surgeons for a single on-orbit crew fatality on the International Space Station (ISS) and subsequent events. Here we detail the operational considerations for a crew fatality should it occur during spaceflight onboard the ISS, including forensic and timeline constraints, behavioral health factors, and considerations for final disposition of decedent remains. Future considerations for differential survival and crewmember fatality outside of low-Earth orbit operations will additionally be discussed, including consideration of factors unique to planetary and surface operations and disposition limitations in exploration spaceflight. While the efforts detailed herein were developed within the constraints of the ISS concept of operations, future platforms may benefit from the procedural validation and product verifications steps described. Ultimately, any response to spaceflight fatality must preserve the goal of handling decedent remains and disposition with dignity, honor, and respect.Stepaniak PC, Blue RS, Gilmore S, Beven GE, Chough NG, Tsung A, McMonigal KA, Mazuchowski EL II, Bytheway JA, Lindgren KN, Barratt MR. Operational considerations for crew fatality on the International Space Station. Aerosp Med Hum Perform. 2023; 94(9):705-714.

Layperson Physiological Tolerance and Operational Performance in Centrifuge-Simulated Spaceflight.

INTRODUCTION: Prior study has indicated that individuals of varied age, medical history, and limited-to-no experience tolerate spaceflight conditions. We sought to expand upon the understanding of layperson response to hypergravity conditions expected in commercial spaceflight by exposing subjects, following minimal training, to centrifuge-simulated, high-fidelity commercial spaceflight profiles. We further explored how these individuals perform in simulated operational activities during and following hypergravity.METHODS: Volunteer subjects participated in up to five centrifuge runs (maximum +4.0 Gz, +4.5 Gx, 6.1 G resultant; onset rate <0.5 Gz · s-1, ≤1 Gx · s-1). Profiles included two winged spacecraft simulations with sequential and combined +Gx/+Gz and two capsule simulations representing nominal +Gx launch and reentry. The final profile simulated a capsule launch abort, with a more dynamic cycling of +Gx exposures and oscillatory multi-axis exposures simulating parachutes and water motion. Touchscreen tablets were used to administer pattern-replication tasks during and after profiles.RESULTS: A total of 46 subjects participated, including 4 diabetics and 9 with cardiac disease. There was increased frequency of motion sickness, subjectively associated with capsule-type profiles, and increased termination of participation compared to prior studies. There was no association between medical history, age, sex, or motion sickness history and tolerance or noncompletion. Tablet test errors were common; accuracy and time to completion were associated with age. There was no association between any time metric or accuracy and sex.DISCUSSION: This study improves understanding of layperson tolerance in commercial spaceflight analog conditions, and the capsular profiles broaden the applicability of the findings. The frequency of task errors highlights the potential for mistakes in operational activities when performed by laypersons.Blue RS, Ong KM, Ray K, Menon A, Mateus J, Auñón-Chancellor S, Shah R, Powers W. Layperson physiological tolerance and operational performance in centrifuge-simulated spaceflight. Aerosp Med Hum Perform. 2023; 94(8):584-595.

Pulmonary Function in Human Spaceflight.

Human spaceflight is entering a time of markedly increased activity fueled by collaboration between governmental and private industry entities. This has resulted in successful mission planning for destinations in low Earth orbit, lunar destinations (Artemis program, Gateway station) as well as exploration to Mars. The planned construction of additional commercial space stations will ensure continued low Earth orbit presence and destinations for science but also commercial spaceflight participants. The human in the journey to space is exposed to numerous environmental challenges including increased gravitational forces, microgravity, altered human physiology during adaptation to weightlessness in space, altered ambient pressure, as well as other important stressors contingent on the type of mission and destination. This chapter will cover clinically important aspects relevant to lung function in a normally proceeding mission; emergency scenarios such as decompression, fire, etc., will not be covered as these are beyond the scope of this review. To date, participation in commercial spaceflight by those with pre-existing chronic medical conditions is very limited, and hence, close collaboration between practicing pulmonary specialists and aerospace medicine specialists is of critical importance to guarantee safety, proper clinical management, and hence success in these important endeavors.

Spaceflight Recovery Considerations for Acute Inhalational Exposure to Hydrazines.

INTRODUCTION: Inhalation of hydrazine or hydrazine-derivative (for example, monomethylhydrazine) vapors during spaceflight operations remains a risk to crew and ground support personnel. Here we sought to provide an evidence-based approach to inform acute clinical treatment guidelines for inhalational exposures during a noncatastrophic contingency spaceflight recovery scenario.METHODS: A review of published literature was conducted concerning hydrazine/hydrazine-derivative exposure and clinical sequelae. Priority was given to studies that described inhalation though studies of alternative routes of exposure were additionally reviewed. Where possible, human clinical presentations were prioritized over animal studies.RESULTS: Rare human case reports of inhalational exposure and multiple animal studies provide evidence of varied clinical sequelae, including mucosal irritation, respiratory concerns, neurotoxicity, hepatotoxicity, hemotoxicity (including Heinz body development and methemoglobinemia), and longitudinal risks. In an acute timeframe (minutes to hours), clinical sequelae are likely to be limited to mucosal and respiratory risk; neurological, hepatotoxic, and hemotoxic sequelae are unlikely without recurrent, longitudinal, or noninhalational exposure.CONCLUSIONS: Acute clinical management should focus on likely clinical concerns as supported by existing data; recovery medical personnel should be prepared to manage mucosal irritation and respiratory concerns, including the potential need for advanced airway management. There is little evidence supporting the need for acute interventions for neurotoxicity and there is no evidence that acute hemotoxic sequelae would drive the need for on-scene management of methemoglobinemia, Heinz body development, or hemolytic anemia. Training that overemphasizes neurotoxic or hemotoxic sequelae or specific treatments for such conditions potentially raises the risk for inappropriate treatment or operational fixation.Hanshaw BC, Ryder VE, Johansen BD, Pattarini JM, Nguyen HN, Nowadly CD, Blue RS. Spaceflight recovery considerations for acute inhalational exposure to hydrazines. Aerosp Med Hum Perform. 2023; 94(7):532-543.

Tolerance of Centrifuge-Simulated Commercial Spaceflight in a Subject with Hemophilia A.

INTRODUCTION: With increasing engagement of commercial spaceflight participants in spaceflight activities, the evaluation of individuals with medical conditions not previously characterized in the spaceflight environment is of particular interest. Factors such as acceleration forces experienced during launch, reentry, and landing of spacecraft could pose an altered risk profile in some individuals due to known disease. Bleeding diatheses present a unique concern in the spaceflight environment given hypergravity exposure and, particularly, the potential for injury resulting from transient or impact acceleration.CASE REPORT: A 26-yr-old Caucasian man with severe hemophilia A and no detectable endogenous Factor VIII (FVIII) volunteered for participation in hypergravity exposures simulating spaceflight. His treatment regimen included 50 IU · kg-1 FVIII-Fc fusion protein intravenous administration every 96 h, with supplemental FVIII administration as needed for injury or bleeding. The subject experienced two profiles at the National Aerospace Training and Research Center (NASTAR), with maximum exposure +4.0 Gz, +4.5 Gx, 6.1 G resultant, and maximum onset rate <0.5 Gz · s-1 and +1 Gx · s-1. The subject reported no abnormal events during the profiles other than brief mild vertigo. No petechial hemorrhage, ecchymosis, or other bleeding was noted during or after profiles. Supplemental FVIII was not required before, during, or after exposure.DISCUSSION: Inherited bleeding disorders present several potential concerns that must be evaluated prior to spaceflight participation. Cautious review and management of medical history, adherence and barriers to treatment, duration of spaceflight and longitudinal management concerns, and a thorough and detailed risk/benefit assessment may provide a future pathway for inclusion of individuals with hematological disorders in commercial spaceflight.Reeves IA, Blue RS, Auñon-Chancellor S, Harrison MF, Shah R, Powers WE. Tolerance of centrifuge-simulated commercial spaceflight in a subject with hemophilia A. Aerosp Med Hum Perform. 2023; 94(6):470-474.

Remains Containment Considerations for Death in Low-Earth Orbit.

BACKGROUND: Maintenance and disposition of decedent remains during spaceflight require the isolation of biohazardous products of decomposition in microgravity and in the absence of refrigeration. Containment and isolation options would preferably offer sufficient time to enable crew and ground support teams to determine appropriate disposition of remains and even potentially return remains to the Earth. The pilot study described herein undertook an effort to develop a postmortem containment unit for the isolation and maintenance of decedent remains in a microgravity environment.METHODS: Commercial off-the-shelf containment units were modified to meet the needs of a microgravity spaceflight environment and to offer the best likelihood of successful containment and management of remains. A subsequent evaluation of modified containment unit performance was undertaken utilizing human cadavers, with measurement and analysis of volatile off-gassing over time followed by impact testing of the units containing cadaverous remains in a simulated spaceflight vehicle seat.RESULTS: Modifications were implemented without significant negative design impact. Failure was observed in one modified unit after 9 d and attributed to improper filter application. The remaining unit successfully contained remains beyond the intended endpoint of the study.DISCUSSION: These pilot efforts offer important insight into the development of effective postmortem containment options for future spaceflight. Further study is needed to ensure repeatability of the findings and to further characterize the failure modes of the modified units evaluated, the impact of microgravity conditions, and the identification of additional modifications that would improve remains disposition.Houser T, Lindgren KN, Mazuchowski EL II, Barratt MR, Haines DC, Jayakody M, Blue RS, Bytheway JA, Stepaniak PC. Remains containment considerations for death in low-Earth orbit. Aerosp Med Hum Perform. 2023; 94(5):368-376.

Blood Glucose Alterations and Continuous Glucose Monitoring in Centrifuge-Simulated Spaceflight.

INTRODUCTION: Sympathetic stimulation is known to be associated with transient alterations of blood glucose (BG) concentration; spaceflight acceleration may be similarly associated with alterations of BG, potentially posing a risk to diabetic individuals engaging in future spaceflight activities. Despite prior studies demonstrating diabetic subjects' tolerance to centrifuge-simulated spaceflight, data are lacking regarding blood glucose response to hypergravity. It remains unclear whether hypergravity or associated physiological response may pose a risk to diabetics. Continuous glucose monitors (CGM) offer a means of noninvasive glucose monitoring and may be useful in spaceflight and analog environments. Here, we describe the results of continuous glucose monitoring during centrifuge-simulated spaceflight.METHODS: Subjects participated in 1-5 centrifuge-simulated spaceflight profiles (maximum +4.0 Gz, +6.0 Gx, 6.1 G resultant). Data collection included heart rate, blood pressure, electrocardiogram, continuous glucose via CGM, intermittent fingerstick BG, and postrun questionnaires regarding symptoms related to hypergravity exposure.RESULTS: CGM data were collected from 26 subjects, including 4 diabetics. While diabetic subjects had significantly higher BG compared to nondiabetics, this was not associated with any difference in symptoms or tolerance. Transient hypergravity-associated CGM glucose alterations did not affect tolerance of the centrifuge experience. CGM data were found to be reliable with occasional exceptions, including four instances of false critical low glucose alarms.DISCUSSION: While further study is necessary to better characterize CGM fidelity during hypergravity and other spaceflight-related stressors, CGM may be a feasible option for spaceflight and analog settings. As in prior studies, individuals with well-controlled diabetes appear able to tolerate the accelerations anticipated for commercial spaceflight.Ong KM, Rossitto JJ, Ray K, Dufurrena QA, Blue RS. Blood glucose alterations and continuous glucose monitoring in centrifuge-simulated spaceflight. Aerosp Med Hum Perform. 2022; 93(9):688-695.

Bellagio II Report: Terrestrial Applications of Space Medicine Research.

AbstractINTRODUCTION: For over 50 yr, investigators have studied the physiological adaptations of the human system during short- and long-duration spaceflight exposures. Much of the knowledge gained in developing health countermeasures for astronauts onboard the International Space Station demonstrate terrestrial applications. To date, a systematic process for translating these space applications to terrestrial human health has yet to be defined.METHODS: In the summer of 2017, a team of 38 international scientists launched the Bellagio ll Summit Initiative. The goals of the Summit were: 1) To identify space medicine findings and countermeasures with highest probability for future terrestrial applications; and 2) To develop a roadmap for translation of these countermeasures to future terrestrial application. The team reviewed public domain literature, NASA databases, and evidence books within the framework of the five-stage National Institutes of Health (NIH) translation science model, and the NASA two-stage translation model. Teams then analyzed and discussed interdisciplinary findings to determine the most significant evidence-based countermeasures sufficiently developed for terrestrial application.RESULTS: Teams identified published human spaceflight research and applied translational science models to define mature products for terrestrial clinical practice.CONCLUSIONS: The Bellagio ll Summit identified a snapshot of space medicine research and mature science with the highest probability of translation and developed a Roadmap of terrestrial application from space medicine-derived countermeasures. These evidence-based findings can provide guidance regarding the terrestrial applications of best practices, countermeasures, and clinical protocols currently used in spaceflight.Sides MB, Johnston SL III, Sirek A, Lee PH, Blue RS, Antonsen EL, Basner M, Douglas GL, Epstein A, Flynn-Evans EE, Gallagher MB, Hayes J, Lee SMC, Lockley SW, Monseur B, Nelson NG, Sargsyan A, Smith SM, Stenger MB, Stepanek J, Zwart SR; Bellagio II Team. Bellagio II report: terrestrial applications of space medicine research. Aerosp Med Hum Perform. 2021; 92(8):650669.

Gynecologic Risk Mitigation Considerations for Long-Duration Spaceflight.

INTRODUCTION: As NASA and its international partners, as well as the commercial spaceflight industry, prepare for missions of increasing duration and venturing outside of low-Earth orbit, mitigation of medical risk is of high priority. Gynecologic considerations constitute one facet of medical risk for female astronauts. This manuscript will review the preflight, in-flight, and postflight clinical evaluation, management, and prevention considerations for reducing gynecologic and reproductive risks in female astronauts.METHODS: Relevant gynecological articles from databases including Ovid, Medline, Web of Science, various medical libraries, and NASA archives were evaluated for this review. In particular, articles addressing preventive measures or management of conditions in resource-limited environments were evaluated for applicability to future long-duration exploration spaceflight.RESULTS: Topics including abnormal uterine bleeding, anemia, bone mineral density, ovarian cysts, venous thromboembolism, contraception, fertility, and health maintenance were reviewed. Prevention and treatment strategies are discussed with a focus on management options that consider limitations of onboard medical capabilities.DISCUSSION: Long-duration exploration spaceflight will introduce new challenges for maintenance of gynecological and reproductive health. The impact of the space environment outside of low-Earth orbit on gynecological concerns remains unknown, with factors such as increased particle radiation exposure adding complexity and potential risk. While the most effective means of minimizing the impact of gynecologic or reproductive pathology for female astronauts is screening and prevention, gynecological concerns can arise unpredictably as they do on Earth. Careful consideration of gynecological risks and potential adverse events during spaceflight is a critical component to risk analysis and preventive medicine for future exploration missions.Steller JG, Blue RS, Burns R, Bayuse TM, Antonsen EL, Jain V, Blackwell MM, Jennings RT. Gynecologic risk mitigation considerations for long-duration spaceflight. Aerosp Med Hum Perform. 2020; 91(7):543-564.

Challenges in Clinical Management of Radiation-Induced Illnesses During Exploration Spaceflight.

INTRODUCTION: Analysis of historical solar particle events (SPEs) provides context for some understanding of acute radiation exposure risk to astronauts who will travel outside of low-Earth orbit. Predicted levels of radiation exposures to exploration crewmembers could produce some health impacts, including nausea, emesis, and fatigue, though more severe clinical manifestations are unlikely. Using current models of anticipated physiological sequelae, we evaluated the clinical challenges of managing radiation-related clinical concerns during exploration spaceflight.METHODS: A literature review was conducted to identify terrestrial management standards for radiation-induced illnesses, focusing on prodromal symptom treatment. Terrestrial management was compared to current spaceflight medical capabilities to identify gaps and highlight challenges involved in expanding capabilities for future exploration spaceflight.RESULTS: Current spaceflight medical resources, such as those found on the International Space Station, may be sufficient to manage some aspects of radiation-induced illness, although effective treatment of all potential manifestations would require substantial expansion of capabilities. Terrestrial adjunctive therapies or more experimental treatments are unavailable in current spaceflight medical capabilities but may have a role in future management of acute radiation exposure.DISCUSSION: Expanded medical capabilities for managing radiation-induced illnesses could be included onboard future exploration vehicles. However, this would require substantial research, time, and funding to reach flight readiness, and vehicle limitations may restrict such capabilities for exploration missions. The benefits of including expanded capabilities should be weighed against the likelihood of significant radiation exposure and extensive mission design constraints.Blue RS, Chancellor JC, Suresh R, Carnell LS, Reyes DP, Nowadly CD, Antonsen EL. Challenges in clinical management of radiation-induced illnesses during exploration spaceflight. Aerosp Med Hum Perform. 2019; 90(11):966-977.

Limitations in predicting radiation-induced pharmaceutical instability during long-duration spaceflight.

As human spaceflight seeks to expand beyond low-Earth orbit, NASA and its international partners face numerous challenges related to ensuring the safety of their astronauts, including the need to provide a safe and effective pharmacy for long-duration spaceflight. Historical missions have relied upon frequent resupply of onboard pharmaceuticals; as a result, there has been little study into the effects of long-term exposure of pharmaceuticals to the space environment. Of particular concern are the long-term effects of space radiation on drug stability, especially as missions venture away from the protective proximity of the Earth. Here we highlight the risk of space radiation to pharmaceuticals during exploration spaceflight, identifying the limitations of current understanding. We further seek to identify ways in which these limitations could be addressed through dedicated research efforts aimed toward the rapid development of an effective pharmacy for future spaceflight endeavors.

Supplying a pharmacy for NASA exploration spaceflight: challenges and current understanding.

In order to maintain crew health and performance during long-duration spaceflight outside of low-Earth orbit, NASA and its international partners must be capable of providing a safe and effective pharmacy. Given few directed studies of pharmaceuticals in the space environment, it is difficult to characterize pharmaceutical effectiveness or stability during spaceflight; this in turn makes it challenging to select an appropriate formulary for exploration. Here, we present the current state of literature regarding pharmaceutical stability, metabolism, and effectiveness during spaceflight. In particular, we have attempted to highlight the gaps in current knowledge and the difficulties in translating terrestrial-based drug studies to a meaningful interpretation of drug stability, safety, and effectiveness in space. We hope to identify high-yield opportunities for future research that might better define and mitigate pharmaceutical risk for exploration missions.

A Preliminary Study of U.S. Air Force Pilot Perceptions of the Pilot-Flight Surgeon Relationship.

INTRODUCTION: Flight surgeons play a vital role in U.S. Air Force aviation operations by ensuring that pilots are medically prepared to meet the demands of military aviation. However, there is natural tension between pilots and flight surgeons. A pilot may be reluctant to share medical information with a flight surgeon who could negatively impact the pilot's career or flight status. In this preliminary study, we sought to identify pilot-perceived strengths and weaknesses in the relationship between U.S. Air Force aviators and their flight surgeons. MATERIALS AND METHODS: An online survey regarding pilot-flight surgeon confidence and perceived values was distributed electronically to a convenience sample of U.S. Air Force aviators. Participants included U.S. Air Force active duty and Air Reserve Component (Air Force Reserve and Air National Guard) military aviators in addition to U.S. Air Force Academy aviation cadets. RESULTS: One hundred and seventy-three aviators participated in the survey. Respondents reported variable comfort in approaching flight surgeons with medical concerns and suggested that they believed other pilots might be withholding medical information from flight surgeons or seeking care from civilian physicians for career protection. CONCLUSIONS: We sought to examine the pilot-flight surgeon relationship and its impact on daily flying operations. While limited, results suggest that there may be gaps in trust between pilots and their flight surgeons. These findings could present an opportunity to improve the pilot-flight surgeon relationship by identifying factors that contribute to closer pilot-flight surgeon relationships.

Thermal Regulation of Emergency Oxygen Supplies in Commercial Space Vehicles.

INTRODUCTION: While NASA requires that commercial spaceflight vehicles provide onboard emergency oxygen supplies for crew, there are currently no requirements in place regarding thermal constraints of delivered gas. The question has been raised whether or not onboard emergency oxygen supplies must be warmed prior to administration to the crew, as inclusion of warming capabilities will increase the complexity and mass of life support systems in the vehicle. We sought to identify the risk of various inhaled oxygen temperatures and resultant pulmonary inflammatory response in potentially injured crewmembers. METHODS: A systematic review of published literature was conducted concerning thermal regulation of inhaled gases, reactive airway response, and inflammatory reactions. In particular, we sought literature that correlated inhaled gas temperature to airway response to identify a temperature threshold that would avoid deleterious sequelae. RESULTS: Cold air inhalation can induce acute bronchoconstriction, increased respiratory rate, and associated dyspnea and hypoxia. Physiological response to cold air varies between healthy lungs and injured tissues, and increased inflammation is associated with increasing airway reactivity. Most studies suggest that inhaled gas temperatures below 10°C may induce deleterious physiological sequelae. DISCUSSION: Best practices would include maintenance of inhaled gas temperatures to >10°C to avoid poor physiological response, preferably as close to physiological norms as possible. Given that inhaled gas temperature may be altered by transit through an oxygen delivery system, measurement of actual delivered gas temperature should occur at the point of crewmember inhalation.Pattarini JM, Blue RS, Alexander DJ. Thermal regulation of emergency oxygen supplies in commercial space vehicles. Aerosp Med Hum Perform. 2018; 89(10):918-922.

Limitations in predicting the space radiation health risk for exploration astronauts.

Despite years of research, understanding of the space radiation environment and the risk it poses to long-duration astronauts remains limited. There is a disparity between research results and observed empirical effects seen in human astronaut crews, likely due to the numerous factors that limit terrestrial simulation of the complex space environment and extrapolation of human clinical consequences from varied animal models. Given the intended future of human spaceflight, with efforts now to rapidly expand capabilities for human missions to the moon and Mars, there is a pressing need to improve upon the understanding of the space radiation risk, predict likely clinical outcomes of interplanetary radiation exposure, and develop appropriate and effective mitigation strategies for future missions. To achieve this goal, the space radiation and aerospace community must recognize the historical limitations of radiation research and how such limitations could be addressed in future research endeavors. We have sought to highlight the numerous factors that limit understanding of the risk of space radiation for human crews and to identify ways in which these limitations could be addressed for improved understanding and appropriate risk posture regarding future human spaceflight.

Prototype Development of a Tradespace Analysis Tool for Spaceflight Medical Resources.

INTRODUCTION: The provision of medical care in exploration-class spaceflight is limited by mass, volume, and power constraints, as well as limitations of available skillsets of crewmembers. A quantitative means of exploring the risks and benefits of inclusion or exclusion of onboard medical capabilities may help to inform the development of an appropriate medical system. A pilot project was designed to demonstrate the utility of an early tradespace analysis tool for identifying high-priority resources geared toward properly equipping an exploration mission medical system. METHODS: Physician subject matter experts identified resources, tools, and skillsets required, as well as associated criticality scores of the same, to meet terrestrial, U.S.-specific ideal medical solutions for conditions concerning for exploration-class spaceflight. A database of diagnostic and treatment actions and resources was created based on this input and weighed against the probabilities of mission-specific medical events to help identify common and critical elements needed in a future exploration medical capability. RESULTS: Analysis of repository data demonstrates the utility of a quantitative method of comparing various medical resources and skillsets for future missions. Directed database queries can provide detailed comparative estimates concerning likelihood of resource utilization within a given mission and the weighted utility of tangible and intangible resources. DISCUSSION: This prototype tool demonstrates one quantitative approach to the complex needs and limitations of an exploration medical system. While this early version identified areas for refinement in future version development, more robust analysis tools may help to inform the development of a comprehensive medical system for future exploration missions.Antonsen EL, Mulcahy RA, Rubin D, Blue RS, Canga MA, Shah R. Prototype development of a tradespace analysis tool for spaceflight medical resources. Aerosp Med Hum Perform. 2018; 89(2):108-114.