Aerospace medicine and human performance最新文献

Introduction: Prolonged exposure to microgravity alters spinal biomechanics, increases disc herniation risk, and complicates perioperative care. With commercial and deep-space missions on the horizon, the need for in-orbit surgical capability has gained prominence as a safeguard for astronaut health.

Methods: A narrative review of PubMed, EMBASE, and Google Scholar through November 2024 identified human, animal, and in vitro studies addressing spinal physiology, pathology, or surgical feasibility in actual or simulated microgravity. Studies unrelated to the spine or lacking English full text were excluded.

Results: Of 988 records, there were 85 that met inclusion criteria. Across study types, microgravity consistently produced spinal elongation, disc swelling, vertebral bone loss, and muscle atrophy, leading to elevated postflight spinal morbidity. Although no spine operations have been reported in orbit, analog studies describe key intraoperative challenges, including fluid containment, sterility, imaging, anesthesia, and hemodynamic control. Promising countermeasures encompass bisphosphonates, resistive exercise, robot-assisted instrumentation, and teleoperation. These data offer a generalizable framework for perioperative planning during long-duration missions.

Discussion: Existing evidence clarifies physiological and logistic barriers to operative care. Targeted musculoskeletal countermeasures, coupled with tele-robotic and augmented-reality platforms, provide a realistic pathway to safe spine surgery during future long-duration missions. Further translational research and on-orbit validation are essential before clinical deployment. Birhiray D, Ghali A, Philipp T, Chilukuri S, Fiedler B, Lawand J, Deveza L. Spine surgery in space. Aerosp Med Hum Perform. 2025; 96(11):1000-1007.

Introduction: Spaceflight Maximum Allowable Concentrations (SMACs) were previously developed for acetaldehyde in 1994. Acetaldehyde is commonly detected at low levels on the International Space Station, and at higher concentrations it might be expected to cause respiratory and eye irritation. Since 1994, numerous exposure studies in human volunteers and laboratory animals have deepened our understanding of potential effects associated with exposure to acetaldehyde vapor.

Methods: A comprehensive literature search was conducted using principles of systematic review to identify toxicological data on acetaldehyde published since 1994. This search was supplemented by the use of summary sources for setting other safety values (i.e., safety values from the U.S. Environmental Protection Agency, occupational limits, etc.).

Results: There were 13 primary toxicology studies identified in this exercise, prompting a re-evaluation of SMACs for all durations. Though the toxicity of acetaldehyde has traditionally been understood as a function of the metabolism of ingested ethanol, scientific publications after 1994 greatly increased our understanding of the toxicological effects of inhaling acetaldehyde vapor. In particular, the development of a physiology-based pharmacokinetic model generated data that was critical to the development of updated SMAC values.

Discussion: The availability of newer data enabled the generation of SMACs for acetaldehyde that are markedly higher than the prior values. The shorter-duration SMACs increased by approximately 10-fold, and the longer-duration SMACs rose by twofold. The proposed values will appropriately protect astronaut health and performance and provide critical information for the design of life-support systems for low Earth orbit and beyond. Williams ES, Tapia CM, Ryder V. Revisions to spacecraft maximum allowable concentrations for acetaldehyde. Aerosp Med Hum Perform. 2025; 96(11):1019-1023.

Introduction: Improved video transmission is needed for telemedicine in austere or remote ground, maritime, and aerospace environments. A prototype compression algorithm named "V-CRAMMIT" (patent pending) streamlines medical images, improving bandwidth efficiency. This study evaluated the technology by assessing diagnostic designations made by medical clinicians using uncompressed vs. compressed video.

Methods: An inventory of deidentified videos was selected from a library of recorded MP4 pulmonary ultrasound scans. Videos displayed four lung pathology conditions: Pneumothorax, Pneumonia, Pleural Effusion, and No Finding/No Pathology. Four videos were selected per condition, yielding 16 recordings compressed using V-CRAMMIT. Average file size reduction was 83%. A total of 20 ultrasound clinicians evaluated each video in both uncompressed and compressed format, presented in a randomized 32-trial sequence. In each trial, subjects selected one of the four pathology designations or an "Inconclusive/Unsure" designation. Trials were presented using a mouse interface and virtual dashboard displaying large-format video, the anatomic location of each scan, a replay button, and response buttons for the above designations. Accuracy, response time, and replay frequency were analyzed using repeated-measures ANOVA incorporating Video format (Uncompressed vs. Compressed) and Pathology (four levels) as independent factors.

Results: Performance did not differ between video conditions: Uncompressed vs. Compressed trials showed no significant differences in accuracy, response times, or replays. Pathology imposed significant effects for all measures, with subjects making the most accurate (91% correct) determinations in Pleural Effusion cases.

Discussion: Streamlined video afforded performance equivalent to standard video and could thus enable improved bandwidth efficiency for remote telemedicine settings. Beer JMA, Ng PC, Wlodarski DC, Tompkins J, Mock J, Mojica A, Clemons M. A streamlined telepresent video platform for aerospace medicine. Aerosp Med Hum Perform. 2025; 96(11):1008-1014.

Introduction: Physiological assessment of military pilots and aircrew is performed annually. This includes a simulation of a flight at maximum altitude (25,000 ft/7620 m) with acute hypoxia, where they can recognize their symptoms. By detecting the symptoms of hypoxia, they will take corrective actions to avoid hypoxia-induced impairment. However, there is little evidence of what happens in the heart under these conditions. Cardiac function can be evaluated noninvasively with transthoracic echocardiography. The objective was to evaluate the effect of hypoxia and altitude during this simulation on systolic and diastolic cardiac function, pulmonary artery systolic pressure, and cardiac output with transthoracic echocardiography.

Methods: A total of 72 volunteers (33.90 ± 8.49 yr, 73.6% male) were studied. A baseline transthoracic echocardiography assessment was performed, and systolic and diastolic function were assessed in both left and right ventricles. Cardiac output and pulmonary artery systolic pressure were estimated. Measurements were repeated at 25,000 ft, with and without oxygen, when saturation was below 80%.

Results: A significant decrease was observed under hypoxic conditions when evaluating both right ventricular (RV) systole (RV 12.25 ± 3.1 to 8.9 ± 2.3 cm · s-1) and diastole (RV 6.8 ± 3.5 to 4.8 ± 2.8 cm · s-1 and RV 8.5 ± 5.2 to 5.71 ± 4.1 cm · s-1). However, cardiac output remained stable (7.87 ± 0.58 to 7.68 ± 0.49 L · m-2).

Discussion: Echocardiography is a useful tool for evaluating left and right cardiac ventricular function. The right ventricle, both in its systolic and diastolic function, was the most affected during a simulated hypobaric and hypoxic flight. Cabrera Schulmeyer MC, Patiño-García D, Alvear M, Aravena D, Montiglio C. Using echocardiography to study the effects of hypoxia and altitude on heart function. Aerosp Med Hum Perform. 2025; 96(11):964-968.

Introduction: Effective execution of the anti-G straining maneuver (AGSM) is essential for pilots to maintain consciousness under high gravitational forces (+Gz). This study evaluated whether electromyographic (EMG) biofeedback enhances muscle activation patterns during AGSM training in novice cadets.

Methods: There were 58 Brazilian Air Force cadets (age: 25 ± 1 yr) who performed two AGSM sessions involving sustained submaximal isometric contractions of the gastrocnemius, vastus medialis, and rectus abdominis muscles, synchronized with rhythmic breathing every 3 s. Subjects completed trials under counterbalanced visual EMG feedback conditions (real-time visualization vs. no visualization) and were randomly assigned to verbal feedback conditions (instructor guidance vs. no guidance). EMG signals were recorded at 1500 Hz and normalized to each subject's peak amplitude during the AGSM trials.

Results: Muscle-specific responses to feedback were observed. Verbal feedback enhanced gastrocnemius activation but reduced vastus medialis activation. Combined visual and verbal feedback produced the highest activation in the rectus abdominis. Visual feedback alone had minimal effect across all muscles. Despite submaximal instructions, brief peak activations were sufficient for normalization.

Discussion: EMG biofeedback facilitated motor learning of AGSM by selectively improving activation in targeted muscles. However, effects varied by muscle group, suggesting the need for tailored instructional strategies. Although task-based normalization offers ecological validity, it may limit comparisons with MVC-based protocols. Incorporating EMG biofeedback may enhance AGSM training, particularly in novice populations or settings without centrifuge access. Massaferri R, Calvo APC, Coutinho ABB, Guimarães TT, Farinatti P. Optimizing muscle activation in cadets using electromyography biofeedback during anti-G training. Aerosp Med Hum Perform. 2025; 96(11):985-992.

Introduction: Astronauts commonly experience space motion sickness, which can impair astronaut performance and safety. Pharmaceuticals are frequently used to reduce space motion sickness symptoms but have not been extensively studied in partial gravity. In this research effort, we investigated the impact of oral promethazine on motion sickness during parabolic flight.

Methods: We collected motion sickness scores from 12 subjects (6 women) during parabolic flight. Each subject participated in two flights-one 0-G flight and one partial g flight-experiencing 10 parabolas at 0 g, 0.25 g, 0.50 g, and 0.75 g. Half of the subjects, counterbalanced by gender, were given 25 mg of oral promethazine before flight and the other half were given a placebo. Motion sickness scores were collected preflight/postflight and during flight.

Results: Pensacola Motion Sickness Questionnaire scores for the placebo group increased from 2.0 (1.55) preflight to 9.17 (5.42) postflight for the 0-G flight, but not for the partial g flight. Subjects in the placebo group reported motion sickness for 51.8% of parabolas compared to 12.6% of parabolas for the promethazine group. All placebo subjects reported some level of motion sickness during flight, while four of the six subjects who received promethazine reported no motion sickness at all.

Discussion: Promethazine was effective at mitigating motion sickness symptoms in both 0 g and partial g. Microgravity conditions (0 g) may be more provocative than partial gravity, possibly due to the greater magnitude of sensory conflict. Further research should continue to investigate motion sickness as a function of hypogravity level. Abbott R, Weinrich MM, Keller NW, Wright TJ, Dunbar BJ, Denise P, Kennedy DM, Diaz-Artiles A. Promethazine effects on motion sickness during altered gravity induced by parabolic flight. Aerosp Med Hum Perform. 2025; 96(11):976-984.

Background: The syndrome of transient headache and neurological deficits with cerebrospinal fluid lymphocytosis (HaNDL syndrome) consists of migraine-like headache episodes with >4 h of hemiparesthesia, dysphasia, and/or hemiparesis plus cerebrospinal fluid lymphocytic pleocytosis. While the rarity of HaNDL syndrome often precludes reassurance of the nature of this syndrome, it has consistently been identified as a benign condition that lasts no longer than 3 mo.

Case report: In the first week of a viral illness, a 29-yr-old male helicopter pilot experienced acute-onset "stumbling" when walking, "nonsensical speech," migraine-like headache, scintillating scotomata, and paresthesias of the tongue and bilateral extremities that lasted for 4-6 h. Work-up included lumbar puncture, revealing lymphocytic pleocytosis. A week later, he experienced word-finding difficulty, right-sided numbness/paresthesia, and severe occipital headache lasting 3 h. A third episode with sensory symptoms involving the tongue and right arm and leg occurred for a few hours 25 d after the onset of the first episode. Symptoms resolved spontaneously. A month following initial discharge, he denied symptom recurrence. Repeat lumbar puncture 4 mo later showed resolution of his pleocytosis. He was considered neurologically recovered 3 mo after symptom onset.

Discussion: This patient's transient episodes were consistent with HaNDL syndrome. His symptom resolution involving three episodes within 25 d reflects the transient nature of this condition. It is critical to recognize HaNDL syndrome as a benign, monophasic disorder that resolves within a maximum of 3 mo so that future pilots with a recent history of HaNDL syndrome may safely and expeditiously return to work. Wetmore EL, Haddon R, Robertson CE, Cowl CT, Elkhatib WY, Garza I. Headache and neurological deficits with cerebrospinal fluid lymphocytosis in a helicopter pilot. Aerosp Med Hum Perform. 2025; 96(10):936-939.

Introduction: As international efforts in space exploration continue, spaceflight dermatology is a critical field for ensuring the health of astronauts. Microgravity, limited hygiene, and radiation uniquely impair skin integrity, contributing to issues such as dermal atrophy, xerosis, and increased infection risk during spaceflight. This commentary highlights practical strategies and potential research avenues for preventing and addressing the array of dermatologic changes during spaceflight. There are multiple promising interventions, including retinoids, vitamin-A derivatives, calcitriol, L-asparaginase, advanced dressings, telemedicine, and immune-system enhancement strategies which may help mitigate skin-thinning, dermatitis, and slow wound-healing. Continued interdisciplinary collaboration, more human data, and real-time data collection will refine and validate strategies, improving skin health in space. Routine consideration of novel dermatologic therapies may benefit spaceflight and overall mission success as humans venture farther into space. Henke J, Kamboj S, Barrett D, Idris H, Gangal A, Blalock T. Therapeutic and diagnostic perspectives for advancing spaceflight dermatology. Aerosp Med Hum Perform. 2025; 96(10):947-949.

Introduction: Magnesium is essential for numerous physiological processes. Changes in magnesium homeostasis during spaceflight could impact astronaut health, particularly as mission durations increase. This review examines trends in serum, urine, and intake-based magnesium data from published human spaceflight studies.

Methods: A systematic search was conducted using scientific and government agency databases. Inclusion criteria were English studies of adult astronauts in spaceflight reporting magnesium measurements (serum, urine, or intake). Magnesium data were extracted across in-flight, landing day, and postflight time points. Percent change from baseline was calculated and regression analyses evaluated trends over time.

Results: A total of 20 studies were included. In-flight data showed an early increase in urine magnesium (+19.3% ± 3.6%) without significant trends over time, while serum magnesium remained stable initially but increased with longer flight duration (β = 0.03). On landing day, serum magnesium was similar (-3.92% ± 0.94%) with a nonsignificant trend toward baseline thereafter (β = 0.15), whereas urine magnesium decreased significantly (-30.01 ± 6.74%), followed by a significant trend toward baseline over time (β = 1.16).

Discussion: Microgravity may be associated with early renal magnesium losses and a progressive increase in serum magnesium. This could be a result of initial fluid shifts and neurohormonal changes, followed by progressive loss from bone and muscle, potentially exacerbated by insufficient dietary intake. Data are limited to missions less than 6 mo, leaving long duration consequences unknown. Further research is needed to confirm trends and explore underlying mechanisms. Diaz TE, Sullivan RD, Ashworth ET, Buesking SC, Haggarty AM, Carmichael BDM, Singh G. Magnesium alterations in human spaceflight. Aerosp Med Hum Perform. 2025; 96(10):919-930.