BACKGROUND: Manually controlled docking of a spacecraft to a space station is an operational task that poses high demands on cognitive and perceptual functioning. Effective processing of visual information is crucial for success. Eye tracking can reveal the operator’s attentional focus unobtrusively and objectively. Therefore, our aim was to test the feasibility of eye tracking during a simulation of manual docking and to identify links between visual information processing and performance.METHODS: We hypothesized that duration and number of gazes to specific regions of interest of the simulation (total dwell time and number of dwells) would be associated with docking accuracy. Eye movements were recorded in 10 subjects (30% women, M = 33.4 yr old) during the 6° head-down tilt bed rest study AGBRESA during 20 training sessions with the 6df learning program for spacecraft docking.RESULTS: Subjects’ gaze was directed most frequently and longest to the vizor (185 dwells and 22,355 ms per task) followed by the two instrument displays (together 75 dwells and 4048 ms per task). We observed a significant positive relationship between number and duration of visual checks of speed and distance to the docking point and the accuracy of the docking maneuver.DISCUSSION: In conclusion, eye tracking provides valuable information related to docking accuracy that might prospectively offer the opportunity to improve docking training effectiveness.Piechowski S, Johannes B, Pustowalow W, Arz M, Mulder E, Jordan J, Wolf OT, Rittweger J. Visual attention relates to operator performance in spacecraft docking training. Aerosp Med Hum Perform. 2022; 93(6):480–486.

BACKGROUND: Modafinil, as a wake-promoting agent, is commonly used to relieve fatigue during military operations. However, there is a lack of clarity regarding the effects of modafinil on the equilibrium and vestibular organs, especially when prescribing this drug to flight crewmembers. The objective of this study was to evaluate the equilibrium- and vestibular-related safety effects of modafinil.METHODS: In a randomized, double-blind, placebo-controlled, crossover study, 10 healthy male volunteers received a single 200-mg oral dose of modafinil or placebo. Equilibrium and vestibular functions were assessed 2 h after oral administration by the sensory organization test (SOT), adaptation test (ADT), and video head impulse test (v-HIT).RESULTS: There was no change in the equilibrium scores of the six SOT conditions or the composite scores between the modafinil and placebo groups. Statistically significant differences were not observed for the sway energy score (SES) in the toe-down test. In the toe-up test, the SES decreased by 16.7% in the modafinil group relative to the placebo group in trial 2, while the differences in other trials were not statistically significant. In the v-HIT, there was no significant difference in the gain of each semicircular canal between the two groups.DISCUSSION: A single 200-mg dose of modafinil did not cause any impairment to vestibular function, equilibrium ability, or adaptive balance response; in fact, modafinil might have a positive effect on adaptation function in healthy volunteers. These findings preliminarily suggest that there is no hidden risk of vestibular dysfunction among aviation employees using modafinil.Liu F, Zhang M, Chen T, Zhai L, Zhang Z, Xue J. Equilibrium and vestibular safety of modafinil in healthy volunteers. Aerosp Med Hum Perform. 2022; 93(6):487–492.

BACKGROUND: Tactical aviators require administration of enhanced inspired oxygen concentrations (hyperoxia) to reduce risk of hypobaric hypoxia and decompression injuries. Hyperoxia is not without consequence; it reduces cerebral perfusion (CBF). Characterizing the relationship between F_IO₂ and CBF is necessary to establish F_IO₂ levels that do not reduce CBF yet are sufficient to mitigate risk of in-flight physiological stressors. To achieve that goal, this study’s objective was to determine whether a dose-response relationship exists between F_IO₂ and CBF and, if so, the F_IO₂ at which CBF significantly declines.METHODS: Healthy male and female subjects (N = 26) were randomized to receive either low dose F_IO₂ of 30%, 40%, 50%, and 100% (Arm 1) or high dose F_IO₂ of 60%, 70%, 80%, and 100% (Arm 2), followed by a return to 21% for both groups. Subjects were placed within a 3-Tesla MRI scanner equipped with pseudocontinuous arterial spin labeling software (pCASL) to measure CBF. Baseline CBF measurements were obtained during exposure to 21% F_IO₂, with subsequent CBF measurements obtained at each predetermined F_IO₂ level.RESULTS: Baseline CBF did not differ between subjects in Arm 1 and Arm 2. Low dose F_IO₂ ≤ 50% did not affect CBF. In contrast, high dose F_IO₂ ≥ 60% significantly reduced CBF. Exposure to 100% F_IO₂ led to similar reductions of CBF for subjects in both Arm 1 and Arm 2.DISCUSSION: The neurovascular system appears to respond to increasing F_IO₂ levels in a dose dependent manner, with significant reductions in CBF with F_IO₂ exposures ≥ 60%.Damato EG, Fillioe SJ, Vannix IS, Norton LK, Margevicius SP, Beebe JL, Decker MJ. Characterizing the dose response of hyperoxia with brain perfusion. Aerosp Med Hum Perform. 2022; 93(6):493–498.

INTRODUCTION: Little has been studied to promote aviation health in South Korea. The aim of this study was to analyze the results of aviation medical examinations conducted in South Korea over the past 5 yr and, in doing so, provide evidence for establishing a health promotion, disease prevention plan.METHODS: Subjects of the study consisted of applicants who underwent aviation medical examinations from January 1, 2016, to December 31, 2020.RESULTS: Over the past 5 yr, the total number of aviation medical examinations in South Korea has shown an annual increase of more than 10%. In the presence of the COVID-19 pandemic in 2020, the number of aviation medical examinations, both renewal and initial, for all types of licenses, except renewal aviation medical examinations for the ATCL, decreased. Disqualification rates were generally higher in initial examinations than in renewal examinations. The examination results for license renewal showed the ATPL disqualification rate to be the highest at 3.5 per 1000 pilots per year in their 50s, with cardiology cases being the most common reason for disqualification, followed by ophthalmology cases and psychiatry cases. Diagnostic categories for those disqualified after initial aviation medical examinations were similar, though ophthalmological causes were most common, followed by cases of psychiatry and neurology.CONCLUSION: Main causes of disqualification in airmen and air traffic controllers were identified as the presence of cardiovascular, ophthalmic, and psychiatric diseases. The results of this study provide evidence for improving health promotion activity plans to manage risk factors of such diseases for aviation workers.Kim JS, Han BS, Kwon YH, Lim J. A 5-yr analysis of aviation medical examinations in South Korea. Aerosp Med Hum Perform. 2022; 93(6):499–506.

BACKGROUND: This pilot study examined the effect of a 2-wk ketogenic diet (KD) compared with a carbohydrate (CHO) diet in military personnel on cognitive performance, mood, sleep, and heart rate variability (HRV).METHODS: A randomized-controlled, cross-over trial was conducted with eight male military personnel (age, 36 ± 7 yr; body mass, 83.7 ± 9.2 kg; BMI, 26.0 ± 2.3 kg · m⁻²). Subjects ingested their habitual diet for 7 d (baseline), then an iso-energetic KD (∼25 g CHO/d) or CHO diet (∼285 g CHO/d) for 14 d (adaptation), separated by a 12-d washout. HRV, fasting capillary blood D-βHB, and glucose concentration, mood, and sleep were measured daily. Cognitive performance was measured on the 7^th day of baseline and the 7^th and 14^th days of adaptation. Data were analyzed using a series of linear mixed models.RESULTS: Mean weekly D-βHB was higher (95% CI, +0.34 to +2.38 mmol · L⁻¹) and glucose was lower (−0.45 to −0.21 mmol · L⁻¹) in the KD compared with the CHO diet. Cognitive performance (Psychomotor Vigilance Task, 2-choice reaction time, and running memory continuous performance test) and mean weekly fatigue, vigor, and sleep (sleep duration, sleep efficiency, and sleep onset latency) were similar between diets. A diet × week interaction for HRV approached significance, with exploratory analyses suggesting HRV was lower compared with baseline during week-2 adapt (−27 to +4 ms) in the KD.DISCUSSION: A 2-wk induction to a KD in male military personnel does not appear to affect cognitive performance, mood, or sleep, but may lower HRV, indicating increased physiological stress.Shaw DM, Henderson L, van den Berg M. Cognitive, sleep, and autonomic responses to induction of a ketogenic diet in military personnel: a pilot study. Aerosp Med Hum Perform. 2022; 93(6):507–516.

INTRODUCTION: Neuro-ophthalmic findings collectively defined as Spaceflight-Associated Neuro-ocular Syndrome (SANS) are one of the leading health priorities in astronauts engaging in long duration spaceflight or prolonged microgravity exposure. Though multifactorial in etiology, similarities to terrestrial idiopathic intracranial hypertension (IIH) suggest these changes may result from an increase or impairing in intracranial pressure (ICP). Finding a portable, accessible, and reliable method of monitoring ICP is, therefore, crucial in long duration spaceflight. A review of recent literature was conducted on the biomedical literature search engine PubMed using the search term “non-invasive intracranial pressure”. Studies investigating accuracy of noninvasive and portable methods were assessed. The search retrieved different methods that were subsequently grouped by approach and technique. The majority of publications included the use of ultrasound-based methods with variable accuracies. One of which, noninvasive ICP estimation by optical nerve sheath diameter measurement (nICP_ONSD), presented the highest statistical correlation and prediction values to invasive ICP, with area under the curve (AUC) ranging from 0.75 to 0.964. One study even considers a combination of ONSD with transcranial Doppler (TCD) for an even higher performance. Other methods, such as near-infrared spectroscopy (NIRS), show positive and promising results [good statistical correlation with invasive techniques when measuring cerebral perfusion pressure (CPP): r = 0.83]. However, for its accessibility, portability, and accuracy, ONSD seems to present itself as the up to date, most reliable, noninvasive ICP surrogate and a valuable spaceflight asset.Félix H, Santos Oliveira E. Non-invasive intracranial pressure monitoring and its applicability in spaceflight. Aerosp Med Hum Perform. 2022; 93(6):517–531.

BACKGROUND: Sightseeing operations are characterized by the presence of passengers as well as favorable light and weather conditions. They include both fixed-wing aircraft and helicopters, an aspect that allows for a comparison of these two types of aircraft in similar operations.METHODS: A total of 95 accident reports from 2008 until 2018 were extracted from the NTSB online database, with each mentioning commercial sightseeing as their operation.RESULTS: Out of a total of 95 accidents, 16 were fatal with a total of 58 people suffering fatal injuries. On average 3.625 people died in each fatal accident. There were significantly more accidents in Alaska and Hawaii than expected. There were significantly more accidents caused by the maintenance crew in helicopters than in airplanes, but significantly more pilot-related accidents in fixed-wing aircraft compared to helicopters. Despite favorable light and weather conditions, 37 accidents reported the environment as a contributing factor to the accident.CONCLUSION: Sightseeing accidents show a pronounced difference between helicopters and airplane accidents that point to different approaches when improving safety in either category. Although night and instrument meteorological conditions are largely absent in the dataset, wind conditions and unsuitable terrain are frequently mentioned. The experience of the pilots and the specific geography of the sightseeing area are likely to affect operational safety the most. The specific dangers of unsuitable terrain affect both helicopters and fixed-wing operations and may be assuaged by specific training or briefings.de Voogt AJ, Hummel Hohl C, Kalagher H. Sightseeing accidents with helicopters and fixed-wing aircraft. Aerosp Med Hum Perform. 2022; 93(6):532–535.

BACKGROUND: Air medical evacuations by tactical aircraft are mandatory in every country, particularly in deployments abroad where hospital resources are limited. In the overseas French departments, it can be particularly useful for military and civilian scientists stationed on the very remote islands of the French Southern and Antarctic Lands. This priority medical support mission uses fixed wing CASA CN235 aircraft and is led by the French Air Force and the French Military Medical Service, in cooperation with the civilian health service.CASE REPORT: The authors present the case of a French soldier with chest trauma on an isolated island who benefited from continuum of care during his air evacuation to Reunion Island.DISCUSSION: This case illustrates that the “CASA Medevac” concept has become a crucial link in the French medical evacuation chain in remote areas. The complex organization, the human material resources, and, finally, the training program are briefly presented.Guénot P, Dubecq C, Colleu F, Dubourg O, Lec C, Bertran P-E. CASA Medevac operations proof of concept in the southern Indian Ocean zone. Aerosp Med Hum Perform. 2022; 93(6):536–539.

INTRODUCTION: Barometric pressure variation during dives may induce barodontalgia and barotrauma. Barodontalgia refers to oral pain resulting from a change in ambient pressure. The aim of this study was to investigate the occurrence of barodontalgia and dental barotrauma among French civilian scuba divers.

METHODS: A nationwide cross-sectional internet-based survey was conducted among French scuba divers over 18 yr of age registered by the French Federation of Underwater Sports (FFESSM). The online questionnaire was distributed from October to December 2020. It contained questions regarding general characteristics of participants, barodontalgia and dental barotrauma occurrences, and relationship of the diver with his/her dentist.

RESULTS: There were 684 scuba divers (65.4% men; aged 48 ± 12 yr) who participated in the study. Barodontalgia was reported by 18.7%, with some respondents reporting more than one episode. Most barodontalgia affected posterior (81.2%) and upper teeth (55.2%) with dental filling (50.0%). At least one dental barotrauma was reported by 10.1% of respondents, including mainly loss or fracture of a dental filling (4.2%). The occurrence of dental barotrauma was significantly higher among men (12.3%) than women (5.9%) and increased significantly with the age, the years of diving and the diving qualification.

CONCLUSION: Information should be provided to divers on the importance of routine dental checkups.

Gougeon K, Yasukawa K, Baudet A. Barodontalgia and dental barotrauma among scuba divers. Aerosp Med Hum Perform. 2022; 93(5):421–425.