INTRODUCTION: Occurrences of severe decompression sickness (DCS) in military parachutist dispatchers at 25,000 ft (7620 m) prompted revision of exposure guidelines for high altitude parachuting. This study investigated residual risks to dispatchers and explored the potential for safely conducting repeat exposures in a single duty period.METHODS: In this study, 15 healthy men, ages 20–50 yr, undertook 2 profiles of repeated hypobaric chamber decompression conducting activities representative of dispatcher duties. Phase 1 comprised two ascents to 25,000 ft (7620 m) for 60 and then 90 min. Phase 2 included three ascents first to 25,000 ft for 60 min, followed by two ascents to 22,000 ft (6706 m) for 90 min. Denitrogenation was undertaken at 15,000 ft (4572 m) with successive ascents separated by 1-h air breaks at ground level.RESULTS: At 25,000 ft (7620 m), five cases of limb (knee) pain DCS developed, the earliest at 29 min. Additionally, multiple minor knee “niggles” occurred with activity but disappeared when seated at rest. No DCS and few niggles occurred at 22,000 ft (6706 m). Early, heavy, and sustained bubble loads were common at 25,000 ft, particularly in older subjects, but lighter and later loads followed repeat exposure, especially at 22,000 ft.DISCUSSION: Parachutist dispatchers are at high risk of DCS at 25,000 ft (7620 m) commensurate with their heavy level of exertion. However, the potential exists for repeated safe ascents to 22,000 ft (6706 m), in the same duty period, if turn-around times breathing air at ground level are brief. Older dispatchers (>40 yr) with functional right-to-left (intracardiac or pulmonary) vascular shunts will be at risk of arterialization of microbubbles.Connolly DM, D’Oyly TJ, Harridge SDR, Smith TG, Lee VM. Decompression sickness risk in parachutist dispatchers exposed repeatedly to high altitude. Aerosp Med Hum Perform. 2023; 94(9):666–677.

INTRODUCTION: Several astronauts have experienced severe headaches during spaceflight, but no studies have examined the associated brain microstructure and functional changes. Head-down-tilted bed rest (HDBR) is a well-established method for studying the physical effects of microgravity on the ground. In this study, we analyzed the changes in brain microstructure and function during headache caused by HDBR using diffusion tensor imaging (DTI) and resting state functional magnetic resonance imaging (R-fMRI).METHODS: We imaged 28 healthy subjects with DTI and R-fMRI in the horizontal supine position and HDBR. Using Tract-Based Spatial Statistics, fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity were compared between the headache and non-headache groups. Additionally, an analysis of functional connectivity (FC) was performed, followed by a correlation analysis between FC and numerical rating scale.RESULTS: HDBR caused headaches in 21 of 28 subjects. DTI analysis showed no significant change in fractional anisotropy after HDBR, whereas axial diffusivity, radial diffusivity, and mean diffusivity increased significantly. R-fMRI analysis showed a significant decrease in FC in several areas after HDBR. The headache group showed significantly higher FC before HDBR, and both groups showed higher FC after HDBR. Correlation analysis showed a positive correlation between FC and numerical rating scale before HDBR but negative after HDBR.DISCUSSION: We demonstrated the image change in the acute phase of space headache by HDBR using DTI and R-fMRI. Changes in brain microstructure and function specific to patients developing headaches may be evaluated by imaging.Goto M, Shibata Y, Ishiyama S, Matsumaru Y, Ishikawa E. Brain microstructure and brain function changes in space headache by head-down-tilted bed rest. Aerosp Med Hum Perform. 2023; 94(9):678–685.

INTRODUCTION: In response to coronavirus disease 2019 (COVID-19), travelers are typically subject to quarantine, which is often associated with poorer mental health (MH). While the protective benefits of community-based exercise are widely recognized, the degree to which this extends to the confined setting is unknown. This systematic review aims to evaluate the effect of exercise on MH in isolating or quarantining adults.METHODS: A literature search of Ovid MEDLINE, APA PsycInfo, and the Cochrane Database of Systematic Reviews limited to January 2019–September 2021 inclusive yielded five eligible studies.RESULTS: Data comprised a total of 2755 college and university students, most of whom were confined. Depending on the scale used, 24.9–76.7% of respondents demonstrated impaired MH, which improved with physical activity (PA), especially when regular and moderate or vigorous. The frequency, duration, and participants of exercise increased as lockdown progressed. One study showed that while sleep, diet, and PA all have an impact on MH, PA was the factor most strongly correlated with MH.DISCUSSION: Physical fitness should be optimized before and maintained during quarantine while exercise space and equipment should be accessible. Importantly, the sustainability of persistent quarantine must be considered given the pervasiveness of COVID-19.Chu V, Newman DG. Exercise effect on mental health in isolating or quarantining adults. Aerosp Med Hum Perform. 2023; 94(9):686–695.

INTRODUCTION: The modern aircraft cockpit has evolved into a complex system of systems. Numerous performance evaluation metrics and techniques exist that can measure the effectiveness of cockpit components in terms of how they influence the human operator’s ability to perform tasks relevant to mission success. As no prior review of these metrics has been found in the literature, this effort attempts to do so, albeit without applying the metrics to a novel cockpit evaluation.METHODS: These metrics and techniques are discussed and presented in five defined categories as they relate to evaluating cockpit subsystems: ergonomics and anthropometrics; human-computer interaction; data management and presentation; crew resource management and operations; and ingress and egress.DISCUSSION: While this effort is significant and novel, it is not necessarily comprehensive. In conclusion, it is noted that no single holistic quantitative metric to evaluate cockpit design and performance yet exists. Utilizing some of the preexisting metrics presented to develop such a metric would be beneficial in efforts to evaluate aircraft cockpit designs and performance, as well as aiding future cockpit designs.Brighton EM, Klaus DM. Categorization of select cockpit performance evaluation techniques. Aerosp Med Hum Perform. 2023; 94(9):696–704.

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.

BACKGROUND: In military aviation, due to high-altitude flight operations, hypoxia training is mandatory and nowadays is mainly done as normobaric hypoxia training in flight simulators. During the last decade, scientific data has been published about delayed recovery after normobaric hypoxia, known as a “hypoxia hangover.” Sopite syndrome is a symptom complex that develops as a result of exposure to real or apparent motion, and it is characterized by yawning, excessive drowsiness, lassitude, lethargy, mild depression, and a reduced ability to focus on an assigned task.CASE REPORT: In this study, we present the case of a 49-yr-old pilot who participated in normobaric hypoxia refreshment training in an F/A-18C Hornet simulator and experienced delayed drowsiness, even 3 h after the training.DISCUSSION: This case report demonstrates the danger of deep hypoxia. Hypoxia training instructions should include restrictions related to driving a car immediately after hypoxia training. In addition, hypoxia may lower the brain threshold for sopite syndrome.Varis N, Leinonen A, Perälä J, Leino TK, Husa L, Sovelius R. Delayed drowsiness after normobaric hypoxia training in an F/A-18 Hornet simulator. Aerosp Med Hum Perform. 2023; 94(9):715–718.

BACKGROUND: Although advanced coronary artery disease in young, healthy fighter pilots is uncommon, an acute cardiac event in flight could be catastrophic.CASE REPORT: After a gym workout, a 31-yr-old F-16 pilot reported severe central chest pain, one vomiting episode, and excessive sweating but no radiation of pain. Electrocardiograph showed ST elevation in V2-V6. Coronary arteriography showed a thrombotic lesion at the proximal left anterior descending (LAD) artery (90%) and one occluded LAD branch with thrombus; the rest of the arteries were normal and ejection fraction was 55%. Primary percutaneous coronary intervention to LAD with one drug-eluting stent was done. The pilot was discharged in stable hemodynamic condition with medication advice. Assessment revealed no significant cardiac risk factors. He did not seek medical care for two central chest pain episodes following a gym workout prior to this event because rest relieved the pain. He gave a history of using commercial protein supplements for bodybuilding in the past 6 yr.DISCUSSION: In this case report, the impact of aggressive gym workouts and chronic use of commercially available bodybuilding protein supplements on cardiovascular health is discussed, as well as aeromedical dilemmas related to this pilot’s career. This case sparks debate about whether a highly motivated young pilot with an unexpected cardiac event should be subjected to regular intensive cardiac evaluation throughout his remaining flying career, with permanent flying limitations, or be motivated to pursue a career shift to facilitate noncomplicated career rehabilitation.Jeevarathinam S, Sabei SA, Wardi YA. Acute myocardial infarction in a young bodybuilder fighter pilot. Aerosp Med Hum Perform. 2023; 94(9):719–722.

INTRODUCTION: Academician Anatoly Ivanovich Grigoriev was a physician, member of the Russian Academy of Sciences Presidium, and a celebrated leader of science in the Soviet Union and Russia—but in the United States, he will be remembered as a friend and mentor. His contributions to space and medicine of extreme environments had a profound impact on human space exploration. He fostered collaboration in many areas of space–human factors, especially in the areas of renal function, endocrinology, and fluids and electrolytes. The joint efforts between NASA and the Soviet/Russian Space Program constitute the foundation for mutual respect and scientific endeavors that continue to transcend the world’s political events.DISCUSSION: This article briefly summarizes Grigoriev’s contributions in our long and historical collaboration in human spaceflight. Multiple sources were used, with much drawn from firsthand knowledge through our personal interfaces and working collaboration.Nicogossian AE, Doarn CR. An American perspective on the legacy of Anatoly I. Grigoriev in space medicine. Aerosp Med Hum Perform. 2023; 94(9):723–727.