INTRODUCTION: The negative effects of hypoxia on human cognitive function have been well documented. In this study we assess the correlation of performance in the SynWin cognitive Multi-Task Battery (MTB) and the onset of hypoxia and describe the use of cognitive assessment scores for real-time hypoxia detection.METHODS: We performed a correlation analysis between MTB scores (Arithmetic, Memory, Audio Monitoring, Video Monitoring tasks) and blood oxygen saturation levels to discover if the scores are good candidates to detect hypoxia. Since this analysis showed positive correlation, we proceeded to develop a parallel decision fusion system that uses these cognitive scores for real-time hypoxia detection using the Neyman-Pearson criterion.RESULTS: We demonstrate that MTB scores have considerable hypoxia detection potential and can be used (if measurable passively) in a real-time detection framework. Analysis of receiver operating characteristic (ROC) curves established a hierarchy of importance of the various MTB modules. The Arithmetic task module had the most significant contribution toward correct hypoxia detection (improvement of ∼13.5% and ∼13.9% in detection accuracy under global false alarms of 0.1 and 0.05, respectively), followed by the Memory and Audio Monitoring modules. Fusion of multiple cognitive assessment scores resulted in significantly higher detection accuracy (>86%) than using any one of the scores by itself.DISCUSSION: When available, cognitive assessment scores can be a useful tool for real-time hypoxia detection. Since these MTB tests also assess neuropsychological functioning, study of distributed detection systems based on MTB scores could help in designing tests that are more useful for detecting hypoxic symptoms.Rajasekar A, Acharya S, Shender BS, Rorres C, Hrebien L, Kam M. Correlation of cognitive scores and the onset of hypoxia. Aerosp Med Hum Perform. 2019; 90(5):429–439.

INTRODUCTION: Microgravity leads to a progressive loss in muscular strength, endurance, and aerobic capacity (Vo_2peak). Blood flow restricted (BFR) exercise has been shown to elicit rapid gains in muscular strength and Vo_2peak. Rowing exercise combined with BFR could be a supplemental countermeasure to maintain preflight muscle function and Vo_2peak, especially within future space vehicles with restricted physical volume.METHODS: There were 20 men who completed 19 min of rowing exercise during CON or BFR in a randomized order. Exercise intensity for all sets was 30% of peak work load achieved during a separate incremental maximal exercise test. Kaatsu training cuffs were inflated around each leg during BFR. Muscle oxygen saturation (Smo₂) and heart rate (HR) were measured throughout exercise and rest. Rate of perceived exertion (RPE) and muscle activation, using surface electromyography (sEMG), were measured during the last 30 s of each exercise set. Blood pressure (BP) and whole blood lactate ([La^-]_b) were measured at rest and postexercise.RESULTS: Smo₂ declined significantly in BFR during exercise and rest by 13% and 14%, respectively. HR and RPE showed significant increases during BFR (120.5 ± 5.53 vs. 128.9 ± 9.86 bts · min⁻¹) (9.8 ± 1.85 vs. 11.8 ± 1.88 arbitrary units). No differences were observed for BP, [La⁻]_b, and sEMG.DISCUSSION: Findings indicate exercise intensity and cuff pressure elicited acute muscular, cardiovascular, and perceptual responses. BFR rowing exercise could be advantageous as an adjunct for future exercise countermeasures where aerobic and anaerobic exercise may be performed on one device or in limited physical space.Mahoney SJ, Dicks ND, Lyman KJ, Christensen BK, Hackney KJ. Acute cardiovascular, metabolic, and muscular responses to blood flow restricted rowing exercise. Aerosp Med Hum Perform. 2019; 90(5):440–446.

BACKGROUND: Manual rendezvous and docking (RVD) is challenging for the astronauts, and automation is used to aid this operation. However, the automation mode in the final approaching stance of RVD is quite different. This paper is aimed at investigating the effect of automation on performance, workload and situation awareness (SA) among novice and expert operators in RVD.METHODS: A two-factor mixed experimental design was adopted. There were 15 novices and 12 experts who participated in the experiment. All subjects were required to finish six tasks of two automation levels: manual RVD and automation-aided RVD. The Performance was assessed by docking result and control process. Workload and SA were measured by NASA Task Load Index and Situation Awareness Rating Techniques (SART). Repeat measures ANOVA and the simple effect test were used to analyze the effect of automation, skill level, and the interaction between them on performance, workload, and SA of operators.RESULTS: Novices exhibited performances inferior to experts, but the skills gap was attenuated as automation was introduced. Moreover, automation can enhance performance, reduce workload, and enhance SA for novices, but potentially deteriorate task performance and SA for the experienced. Mediation analysis results indicated automation was a significant predictor of workload and SA, b = -0.576 and b = 0.503, and workload and SA were significant predictors of docking result, b = -0.590 and b = 0.348.CONCLUSION: Automation can be detrimental to various elements of the functioning of highly experienced operators. Moreover, automation affects docking result by affecting workload and SA.Du X, Niu J, Zhang Y, Wang M, Wang D, Wu B, Cai J, Huang W. Performance, workload, and situation awareness in manual and automation-aided rendezvous and docking. Aerosp Med Hum Perform. 2019; 90(5):447–455.

BACKGROUND: Although several studies have shown that an individual’s career influences the brain structure, no study has examined cortical asymmetry in civil aviation pilots. This study focused on hemispheric cortical asymmetries in Chinese civil aviation pilots.METHODS: The MRI structural images of 1065 healthy captains of the Civil Aviation Administration of China were analyzed using a surface-based automated parcellation approach, and hemispheric asymmetries in the global and regional cortical thickness of their brains were examined.RESULTS: The hemispheric asymmetries were relatively significant. In total, 58 regions out of 74 were clearly asymmetrical. Generally, rightward asymmetries (reduction left) were found in slightly more regions than leftward asymmetries. The study also revealed leftward asymmetries mainly throughout the lateral, dorsal, and mesial surfaces of the frontal lobe, extending into the primary sensory, superior parietal, and anterior temporal cortices. In addition, the rightward asymmetries were mainly located in the temporal and occipital cortices.DISCUSSION: Compared with previous studies, in this study, the structural lateralization of the cortical thickness was more significant. Most of the results were in agreement with those of previous studies, although there were different results in some regions. Functional structural lateralization was demonstrated among the regions. Hemispheric differences in the thickness of the cortex might be related to hemisphere-specific functional specializations that may be associated with behavioral asymmetries.Cao Y, Qiu C, Zhao C, Zhang Y, Qi Y, Li S. Hemispheric asymmetries of cortical thickness in civil aviation pilots. Aerosp Med Hum Perform. 2019; 90(5):456–461.

BACKGROUND: Middle-ear barotrauma is a common problem reported by aircrew members and passengers. Studies have shown that 20–50% of passengers report ear complaints during the flight or after landing. The aim of this study is to determine the prevalence of otitis media with effusion in aircrew members and describe the time to resolution of the condition.METHODS: All aircrew members presenting at Civil Aviation Center at Congonhas Airport at São Paulo for annual flight medical examinations from September 2014 to May 2015 were reviewed retrospectively for the presence of otologic disorders. Eligible participants were all pilots, copilots, and flight attendants with a diagnosis of otitis media with effusion confirmed by immittance testing.RESULTS: Of 1607 aircrew members, 155 (9.65%) were diagnosed as having otitis media with effusion. Most participants were men (51.6%). Regarding aircrew position, 81.9% were flight attendants, 11.6% were copilots, and 6.5% were pilots. The mean time to resolution of the otitis media was 8.23 (± 3.02) days.DISCUSSION: Otolaryngologists must be aware of the effects of gas expansion in the middle ear at higher altitudes for the appropriate treatment of diseases related to pressure changes. The recommendation for an aircrew member to return to flying duties should occur only after the individual has been treated and complete resolution, confirmed by immittance testing, has been documented.Pinto JA, dos Santos Sobreira Nunes H, dos Santos RS, Cavallini A, Freitas G, Knoll D, Duarte C. Otitis media with effusion in aircrew members. Aerosp Med Hum Perform. 2019; 90(5):462–465.

BACKGROUND: Airline crew are being exposed to extended workdays and compressed work periods, with quick returns between duties, implying a heightened physiological and psychological strain that may lead to sleep deprivation and fatigue. The aim of the study was assessment of the effect of an extended day of flight duty and a compressed work week with regard to recovery, cumulative fatigue, and neurobehavioral performance.METHODS: We followed 18 pilots and 41 cabin crewmembers during four consecutive days of flight duty, comprising a total of ≥ 39 h, where the first day was ≥ 10 h. Information on demographics, work characteristics, health status, and physical activity was collected at baseline. Subjects completed logs for the first and fourth workday, including the Samn-Perelli Fatigue Checklist at three time points during these workdays. Two computer-based neurobehavioral tests were completed the evening prior to the first shift, and after the first and the fourth day of the work period.RESULTS: Number of flight sectors during the work period was 10–20. Self-reported fatigue levels increased during the workdays. Neurobehavioral test-scores did not deteriorate. The effects of each additional flight sector during the work period was elevated reaction times (RT) both among cabin crewmembers (B = 5.05 ms, 95% CI 0.6, 9.5) and pilots (B = 4.95 ms, 95% CI 0.4, 9.5). Precision was unaffected.DISCUSSION: Airline pilots and cabin crewmembers seem to obtain satisfactory sleep before and during the period of 4 consecutive days. The association between multiple flight sectors and increased fatigue supports previous findings.Goffeng EM, Wagstaff A, Nordby K-C, Meland A, Goffeng LO, Skare Ø, Lilja D, Lie J-AS. Risk of fatigue among airline crew during 4 consecutive days of flight duty. Aerosp Med Hum Perform. 2019; 90(5):466–474.

BACKGROUND: Carbon dioxide (CO₂) toxicity could be catastrophic for astronauts. Suppressing metabolism by lowering body temperature decreases CO₂ production and may facilitate rescue in the event of a crippled ship. Lowering body temperature requires shivering suppression. We evaluated dexmedetomidine to facilitate cooling of healthy individuals.METHODS: Following consent, we administered a 1 mcg · kg⁻¹ bolus of dexmedetomidine followed by continuous infusion (0.5–1.4 mcg · kg⁻¹ · h⁻¹) for 3 h of cooling. We cooled subjects using a bolus of 30 cc · kg⁻¹ of 4°C saline followed by surface cooling. We measured vital signs, thermal and comfort scales, sedation, and shivering for 3 h and during recovery. ANOVA evaluated changes in measures over time.RESULTS: Nine subjects completed the study. Mean age was 31 (SD 8) yr, mean mass was 71 (SD 14) kg, height of 168 (SD 9) cm, and body mass index of 25 (SD 3). Median time to 1°C drop in core temperature was 16 (IQR 15, 32) min. Temperature changed over time with median lowest temperature being 33.1°C (IQR 32.8°C, 34.1°C). Neither heart rate nor diastolic blood pressures changed over time. Systolic blood pressure decreased over time. Subjects responded to verbal stimuli and completed tasks throughout the protocol. During cooling and maintenance, subjects reported discomfort and the sensation of being cold.CONCLUSION: Dexmedetomidine facilitates shivering suppression during prolonged cooling in healthy individuals. Subjects are easily roused, have mild decreases in systolic blood pressure, and note sensations of discomfort and cold. Cooling to suppress metabolism is a feasible countermeasure to prolong astronaut endurance.Rittenberger JC, Flickinger KL, Weissman A, Repine M, Elmer J, Guyette FX, Callaway CW. Cooling to facilitate metabolic suppression in healthy individuals. Aerosp Med Hum Perform. 2019; 90(5):475–479.

INTRODUCTION: Modafinil is a wakefulness-promoting stimulant that has been approved by the Republic of Singapore Air Force (RSAF) as a fatigue countermeasure medication since 2011. Each RSAF aircrew member must undergo a ground test to exclude operationally relevant adverse drug effects prior to consuming the medication for operational reasons. This study describes the RSAF’s modafinil ground testing outcomes over a 7-yr period.METHODS: This is a retrospective case series of 243 RSAF aircrew members who underwent modafinil 100-mg test dosing over the 7-yr period from September 2011 to September 2018.RESULTS: The median age was 31 yr (range, 21–53 yr) and mean age was 31.7 yr ± 6.19 yr. Of the aircrew members, 234 (96.3%) were men and all were of Asian ethnicity. Of the subjects, 237 (97.5%) were medically cleared for the operational use of modafinil. Among the six (2.47%) who failed modafinil ground testing, headache (cumulative incidence, 1.65%), anxiety (cumulative incidence, 0.41%), diarrhea (cumulative incidence, 0.41%), and insomnia (cumulative incidence, 0.41%) were reported as the side effects experienced. None of the aircrew members experienced major adverse drug events.DISCUSSION: Our findings suggest a low occurrence of adverse drug effects among military aircrew members who undergo modafinil test dosing prior to using the drug operationally. To our knowledge, this is the single largest published case series of modafinil ground testing outcomes among Asian military aviators.Ooi T, Wong SH, See B. Modafinil as a stimulant for military aviators. Aerosp Med Hum Perform. 2019; 90(5):480–483.

INTRODUCTION: This study explores the safety risk due to delayed detection of hazardous health conditions that would result from increasing the duration of U.S. first-class aeromedical certificates from 6 mo to 12 mo for pilots ages 40 yr old through 60 yr old.METHODS: All pilots who submitted a U.S. first-class application in 2014 with no electrocardiogram and with the previous exams 4.5 to 7.5 mo prior were selected from the FAA pilot medical database. Proportions of Federal Aviation Administration (FAA) denial pathology codes and Aviation Medical Examiner (AME) deferrals were compared for these exams within and between age groups from 40 yr old through 75 yr old. The absolute incidence rates for delayed detection were calculated and relative incidence of these proportions was compared graphically.RESULTS: The relative risk between age groups for delayed identification of disqualifying medical conditions showed that the 56–60-yr-old group would be at about twice the risk as the 40–45-yr-old group. The absolute incidence for the 56–60-yr-old group was 0.46% for denial conditions and 0.60% for AME deferrals over 6 mo.DISCUSSION: Increasing FAA first-class medical certificate duration from 6 mo to 12 mo would put 56–60-yr-old pilots at double the currently accepted risk for delayed detection of significant medical conditions. The absolute risk for this 6-mo delayed identification for the 56–60-yr-old group would average 0.53%.Mills WD, DeJohn CA. Safety implications of 6-month vs. 1-year first-class aeromedical certificates. Aerosp Med Hum Perform. 2019; 90(5):484–487.

INTRODUCTION: The Federal Aviation Administration Office of Aerospace Medicine (AAM) is required by law to identify pilots who have driving under the influence (DUI) convictions. It is the responsibility of AAM to determine, based on the DUI, if the pilot has a drinking problem and needs follow-up treatment. Pilots with alcohol problems are at risk to themselves and the public and need to have treatment to reduce the extent of the risk. It has been suggested by some that a blood alcohol concentration (BAC) of 0.15 g · dL⁻¹ is evidence of tolerance and the pilot should be placed in an alcohol treatment program.METHOD: The National Institute on Alcohol Abuse and Alcoholism (NIAAA) Clinician’s Guide considers a person at risk for a drinking problem when a man drinks 5 or more drinks or a woman drinks 4 or more drinks in a day and reaches a 0.08 g · dL⁻¹ of ethanol in the blood. It is possible to estimate from a BAC or breath alcohol concentration (BrAC) the number of drinks consumed using the volume of distribution for ethanol and the weight of the individual. A spread sheet tool was developed to estimate the number of drinks consumed.RESULTS: It was determined that DUI/DWI concentrations could be used to determine the minimum number of drinks consumed. Overweight people reach binge drinking levels and higher Hingson levels at lower DUI/DWI concentrations than people with an average weight or lower.DISCUSSION: Using this tool there is a high probability (99.7%) of identifying a true binge drinker.Canfield DV, Forster EM, Cheong Z-I, Cowan JM. Breath/blood alcohol concentration as an indicator of alcohol use problems. Aerosp Med Hum Perform. 2019; 90(5):488–491.

Shields JL. You’re the flight surgeon: potential migraine in an Air Force aviator—to diagnose or not to diagnose. Aerosp Med Hum Perform. 2019; 90(5):494–496.

Zhang JJ. You’re the flight surgeon: airman with emotional trauma following deployments. Aerosp Med Hum Perform. 2019; 90(5):496–500.