Aerospace medicine and human performance最新文献

Introduction: Heart muscle diseases are challenging for the aeromedical examiner due to their heterogeneous nature and widely varying natural history. The diagnosis of heart muscle disease is likely to have a significant impact on flying privileges, with the risk assessment requiring careful testing and careful follow up. Consideration must also be given to the treatments used in each individual, as these may also pose an aeromedical risk. In athletic aircrew, differentiating athletic adaptation from a cardiomyopathy is essential to decide if flying restrictions are necessary.

Case presentation: This article provides insights into the appropriate investigation of aircrew with suspected or proven heart muscle disease, to assist with licensing decisions. Four case vignettes are presented (myocarditis, hypertrophic cardiomyopathy, dilated cardiomyopathy, and athletic heart) to give a broad overview of the commonest areas of heart muscle disease seen in aircrew. The relevant features of evaluation, treatment, and aeromedical relevance are provided in a brief discussion of each case.

Discussion: This paper presents the most current recommendations for assessing aircrew with heart muscle disease and cardiomyopathy with data derived from current aeromedical and clinical literature, as well as the expert consensus of the NATO Working Groups on Occupational Cardiology (HFM WG 251, 316) D'Arcy J, Syburra T, Broekhuizen L, Holdsworth D, Guettler N, Bron D, Manen O, Davenport E. Structural heart disease in aircrew. Aerosp Med Hum Perform. 2026; 97(2):116-122.

Introduction: 1-Propanol is a volatile organic compound commonly used as a solvent for industrial and pharmaceutical products. It has been consistently detected at low concentrations in the International Space Station. Although there are published spacecraft maximum allowable concentrations (SMACs) for its less toxic isomer 2-propanol, no SMACs were previously established for 1-propanol. This document reviews existing literature on 1-propanol inhalation toxicity to derive acute and long-term SMACs applicable to off-nominal and nominal scenarios, respectively.

Methods: Electronic databases and published literature were searched for relevant toxicity data on 1-propanol inhalation. Keywords "1-propanol" and "n-propanol" were used, and hits were further screened by the key phrase "inhalation toxicity."

Results: Most studies identified were acute inhalation toxicity using animal models. Mice exposed to 3250 ppm of 1-propanol for 1.5-2 h experienced central nervous system depression mimicking alcohol intoxication. No adverse effects were reported in mice or rats exposed to 1600 ppm for 120 h, but exposure to 7000 ppm for 294 h resulted in reduced male fertility.

Discussion: To preclude central nervous system depression, 1-h and 24-h SMACs for 1-propanol were set at 205 and 100 ppm, respectively. A limit of 60 ppm for 7 d was based on lack of effects at 1600 ppm for 120 h. SMACs for 30, 180, and 1000 d were set at 35 ppm to preserve male fertility. Resulting values are approximately half of the recently updated SMAC values for 2-propanol, which is consistent with the trend between the other published exposure limits of these two isomers. Ryder VE, Yap DA. Spacecraft maximum allowable concentrations for 1-propanol. Aerosp Med Hum Perform. 2026; 97(1):60-63.

Introduction: It is possible that a single clinical blood pressure (BP) reading, as currently practiced in the Indian Air Force, may not be able to establish hypertensive status. This study examined whether at higher body mass indexes (BMI), 24-h ambulatory blood pressure monitoring (ABPM) would be a better tool for detecting latent hypertension vis-à-vis clinical BP recording.

Methods: In this study, 230 healthy, male, clinically normotensive (BP <140/90 mm of Hg) subjects between 20-40 yr of age were included: 50 with normal BMI (<25 kg · m-2), 120 overweight (BMI 25-29.99 kg · m-2), and 60 obese (BMI ≥ 30 kg · m-2). Each subject underwent BMI measurement, clinical BP recording, and 24-h ABPM. Correlation analysis, analysis of variance, and Chi-squared tests were used for statistical analysis of the data.

Results: A statistically significant positive correlation was observed between mean arterial pressure and BMI. The 24-hour ABPM revealed a significant effect of BMI on mean arterial pressure, which was not observed in clinical BP measurement. The hypertensive response shown by ABPM was statistically significant between obese and normal BMI as well as obese and overweight groups. This was not statistically significant between normal BMI and overweight groups. ABPM also revealed a consistent statistically significant blunting of nocturnal dip response with increasing BMI.

Discussion: Among the obese, 24-h ABPM was found to be useful for hypertension screening and is recommended as an assessment tool for hypertension screening in medical evaluation of obese personnel. Tripathy NK, Joshi VV, Raghunandan V. Evaluating air force personnel with higher body mass indexes by monitoring ambulatory blood pressure. Aerosp Med Hum Perform. 2026; 97(1):42-46.

Introduction: Exposure to prolonged microgravity is associated with cephalad fluid shifts that potentially could affect tympanomastoid ventilation and auditory mechanisms. We conducted a retrospective review of NASA astronaut on-orbit hearing assessments (OOHAs) and middle-ear pressure measurements obtained during International Space Station missions to search for evidence of spaceflight-related hearing changes and disturbances of middle-ear aeration.

Methods: Nine NASA astronauts conducted on-orbit hearing assessments and tympanometry at least twice while on space station missions. Kuduwave audiometric instrumentation was used for self-administered air-conduction hearing tests and pressure measurements. Pre- and postflight conventional audiometric data were also reviewed.

Results: OOHAs showed low-frequency mean hearing threshold increases up to 10 dB compared to the preflight Kuduwave baseline. The magnitude of these changes did not correlate with length of time on the space station. Tympanometry was normal in each of 29 measurements that were technically adequate. Postflight audiograms revealed mild residual differences from preflight testing at low frequencies.

Discussion: The results suggest relative resilience of auditory function overall and maintenance of tympanomastoid aeration through prolonged orbital spaceflight, but with evidence of generally small low-frequency hearing threshold increases in some astronauts. Our audiometric findings warrant confirmation and further study of outliers with the larger cohort of NASA astronauts for whom hearing data were obtained with earlier OOHA instrumentation. Wexler DB, Robinette MB, Coble CW, Coste A, Hoffman T, Danielson R. Hearing assessments and tympanometry in NASA astronauts on the International Space Station. Aerosp Med Hum Perform. 2026; 97(1):26-35.

Introduction: Aeromedical evacuation of patients with post-traumatic orbital emphysema following zygoma and orbital floor fractures has often been viewed with considerable concern. The expansion of intra-orbital air with increasing altitude can theoretically result in orbital tension, which can lead to blindness. This concern is mainly based on extremely rare case reports and theoretical models rather than significant clinical experience. The purpose of this work is to evaluate hazards and complications associated with aeromedical evacuation of combat casualties with post-traumatic orbital emphysema following zygoma and orbital floor fractures.

Methods: We report the results of a series of 12 patients with post-traumatic orbital emphysema who were evacuated from a combat theater by military aircraft over a long distance. All military patients referred to a military hospital in France with CT-identified zygoma and/or orbital floor fracture repatriated via tactical aeromedical intervention from January 2020 to January 2022 were analyzed. An ophthalmological examination with visual acuity measurement and a new CT scan of the facial mass without injection were performed after evacuation.

Results: There were 12 patients referred. None of the patients had any complications. Only one soldier, who blew his nose during the trip, had an increase in subcutaneous emphysema without any impact on his vision. There was one minimal displacement of the fracture secondary to a nose blowing without significant impact.

Discussion: Orbital emphysema in facial injuries is not likely in itself to be a contraindication to immediate air evacuation in the case of zygoma and orbital floor fracture. Crambert A, Ballivet de Regloix S, Haen P, Morvan J-B, Caruhel J-B. Early aeromedical evacuation for orbital emphysema after zygoma and orbital floor fractures. Aerosp Med Hum Perform. 2026; 97(1):55-59.

Introduction: Fatigue poses a serious risk to safety and performance in military aviation. Rotary-wing pilots operating in mountainous regions face unique physiological and cognitive demands, yet few studies evaluate both objective factors and subjective fatigue during real-world missions.

Methods: This study assessed fatigue in 25 UH-60 Black Hawk pilots and copilots during daytime visual flights in Tunceli, Türkiye. Measurements were taken at three phases: pre-, in, and postflight. Physiological factors (heart rate, oxygen saturation) and subjective fatigue (Samn-Perelli scale) were recorded. Paired-sample and Welch's independent t-tests were used for analysis.

Results: Oxygen saturation significantly declined from preflight (M = 96.2%) to in flight (M = 94.3%) and partially recovered postflight (M = 95.2%). Heart rate changes across phases were not statistically significant, although preflight heart rate was higher in copilots (M = 105.2 bpm) than in pilots (M = 87.8 bpm). Samn-Perelli scores rose significantly from pre- (M = 1.8) to postflight (M = 3.8), indicating perceptual fatigue accumulation. Copilots also reported greater preflight fatigue.

Discussion: Even moderate helicopter missions at altitude can cause measurable fatigue. The divergence between physiological recovery and subjective fatigue highlights the need to combine biometric and perceptual tools in fatigue monitoring and mission planning. Gevrek I, Ata N, Gevrek MI, Eroglu C. Physiological factors and subjective fatigue monitoring in helicopter pilots during UH-60 missions. Aerosp Med Hum Perform. 2026; 97(1):20-25.

Introduction: Spaceflight presents unique challenges to ocular health, as visual disturbances such as dry eye symptoms have been frequently reported by astronauts. Matrix metalloproteinases (MMPs), a family of extracellular matrix-degrading enzymes, are known mediators of ocular surface inflammation and tissue remodeling on Earth, particularly in dry eye disease. This review explores the potential role of MMPs in spaceflight-associated ocular conditions, including spaceflight-associated dry eye syndrome and spaceflight-associated neuro-ocular syndrome.

Methods: We searched literature on topics relating to metallomatrix proteins and spaceflight using databases PubMed, MedLine, Embase, and Central from inception to April 2025.

Results: Although there are limited studies on direct measurements of tear MMPs during spaceflight, indirect clinical evidence and analog studies suggest that microgravity, radiation, and systemic inflammation may upregulate MMP expression. This contributes to epithelial barrier disruption and impaired wound healing. Rodent models and simulated microgravity experiments further support the mechanosensitive regulation of MMPs across various tissues.

Discussion: Given the safety and accessibility of tear collection, MMPs may be useful biomarkers for assessing ocular and systemic changes in astronauts. Understanding MMP expression and regulation in space may inform preventive strategies to preserve vision during long-duration missions. Stephanian B, Ong J, Lee R, Gibson R, Berdahl J, Waisberg E, Mader TH, Lee AG. Ocular matrix metalloproteinases in spaceflight. Aerosp Med Hum Perform. 2026; 97(1):47-54.

Introduction: Exposure to head-to-toe acceleration (Gz) may lead to G-induced loss of consciousness due to reduced head-level blood pressure and flow. Despite various countermeasures, G-induced loss of consciousness remains a safety concern, causing accidents and fatalities. Inhalation of 5% carbon dioxide (CO2) and higher concentrations can improve G-tolerance but lead to adverse symptoms. This study investigated the impact of 5% and lower concentrations of CO2 on the cardiovascular system during orthostatic stress.

Methods: To simulate +Gz cardiovascular effects, 20 healthy subjects (11 males, 9 females) were exposed to 5 gas mixtures (room air, 2%, 3%, 4%, and 5% CO2) while undergoing lower body negative pressure of -60 mmHg combined with an 80° head-up tilt. Cardiovascular and respiratory parameters were continuously monitored and subjective symptoms were assessed.

Results: Compared to room air, breathing 5% CO2 significantly increased systolic (+18.4 ± 16.4 mmHg), diastolic (+30.0 ± 9.5 mmHg), and mean arterial (+26.1 ± 11.0 mmHg) blood pressure during orthostatic stress. However, this was also associated with a perceived increase in breathlessness (median 2.5, interquartile range 1.25-3) and difficulty breathing (median 2, interquartile range 1-3). Lower concentrations of CO2 were better tolerated but did not significantly affect physiological response during orthostatic challenge.

Discussion: These findings suggest breathing higher concentrations of CO2 (5%) can elicit significant cardiovascular changes which potentially could increase G-tolerance, although they are also associated with respiratory discomfort in some individuals. However, as this is an exploratory study, further research that more accurately replicates the complex physiological changes that occur during Gz exposure is still required. Twardowska K, Bortnowschi M, Skert R, Lee Y-H, Rafferty G, Pollock R. Cardiovascular effects of hypercapnia during lower body negative pressure and head-up tilt. Aerosp Med Hum Perform. 2026; 97(1):3-10.