INTRODUCTION: Exposure to low oxygen environments (hypoxia) can impair cognitive function; however, the time-course of the transient changes in cognitive function is unknown. In this study, we assessed cognitive function with a cognitive test before, during, and after exposure to hypoxia.METHODS: Nine participants (28 4 yr, 7 women) completed Conners Continuous Performance Test (CCPT-II) during three sequential conditions: 1) baseline breathing room air (fraction of inspired oxygen, F_Io₂ 0.21); 2) acute hypoxia (F_Io₂ 0.118); and 3) recovery after exposure to hypoxia. End-tidal gas concentrations (waveform capnography), heart rate (electrocardiography), frontal lobe tissue oxygenation (near infrared spectroscopy), and mean arterial pressure (finger photoplethysmography) were continuously assessed.RESULTS: Relative to baseline, during the hypoxia trial end-tidal (-30%) and cerebral (-9%) oxygen saturations were reduced. Additionally, the number of commission errors during the CCPT-II was greater during hypoxia trials than baseline trials (2.6 0.4 vs. 1.9 0.4 errors per block of CCPT-II). However, the reaction time and omission errors did not differ during the hypoxia CCPT-II trials compared to baseline CCPT-II trials. During the recovery CCPT-II trials, physiological indices of tissue hypoxia all returned to baseline values and number of commission errors during the recovery CCPT-II trials was not different from baseline CCPT-II trials.DISCUSSION: Oxygen concentrations were reduced (systemically and within the frontal lobe) and commission errors were increased during hypoxia compared to baseline. These data suggest that frontal lobe hypoxia may contribute to transient impairments in cognitive function during short exposures to hypoxia.Uchida K, Baker SE, Wiggins CC, Senefeld JW, Shepherd JRA, Trenerry MR, Buchholtz ZA, Clifton HR, Holmes DR, Joyner MJ, Curry TB. A novel method to measure transient impairments in cognitive function during acute bouts of hypoxia. Aerosp Med Hum Perform. 2020; 91(11):839844.

INTRODUCTION: Exposure to hypoxia has a deleterious effect on cognitive function; however, the putative effect of hypobaria remains unclear. The present study aimed to evaluate cognitive performance in pilot trainees who were exposed to acute normobaric (NH) and hypobaric hypoxia (HH). Of relevance for military pilots, we also aimed to assess cognitive performance in hypobaric normoxia (HN).METHODS: A total of 16 healthy pilot trainees were exposed to 4 randomized conditions (i.e., normobaric normoxia, NN, altitude level of 440 m; HH at 5500 m; NH, altitude simulation of 5500 m; and HN). Subjects performed a cognitive assessment (KLT-R test). Cerebral oxygen delivery (cDO₂) was estimated based middle cerebral artery blood flow velocity (MCAv) and pulse oxygen saturation (S_po₂) monitored during cognitive assessment.RESULTS: Percentage of errors increased in NH (14.3 9.1%) and HH (12.9 6.4%) when compared to NN (6.5 4.1%) and HN (6.0 4.0%). Number of calculations accomplished was lower only in HH than in NN and HN. When compared to NN, cDO₂ decreased in NH and HH.DISCUSSION: Cognitive performance was decreased similarly in acute NH and HH. The cDO₂ reduction in NH and HH implies insufficient MCAv increase to ensure cognitive performance maintenance. The present study suggests negligible hypobaric influence on cognitive performance in hypoxia and normoxia.Aebi MR, Bourdillon N, Noser P, Millet GP, Bron D. Cognitive impairment during combined normobaric vs. hypobaric and normoxic vs. hypoxic acute exposure. Aerosp Med Hum Perform. 2020; 91(11):845851.

BACKGROUND: The vestibular system is important in the pathogenesis of seasickness. Our objective is to investigate whether routine vestibular tests detect seasickness.METHODS: Included were 17 professional naval personnel (mean age of 29.76 4.73 yr) diagnosed as having seasickness and 29 healthy age- and gender-matched controls. Cervical (c) vestibular evoked myogenic potentials (VEMP) and ocular (o) VEMP and bithermal caloric tests were performed after ear, nose, and throat examination, pure tone audiometry, and magnetic resonance imaging. Severity of seasickness was evaluated based on the Graybiel scale. P1 latency, N1 latency, P1N1 amplitude, and interaural asymmetry ratios (IAR) of cVEMP and oVEMP were compared between the patients and control groups. Abnormal findings in the caloric test were noted. Presence of an abnormality in any of the three vestibular tests (cVEMP, oVEMP, or caloric test) was accepted as a positive vestibular finding.RESULTS: According to the Graybiel Scale, severe malaise and frank sickness were observed in 3 patients (18.7%) and 13 patients (81.3%), respectively. Graybiel scoring could not be performed in one patient due to general discomfort and bad general condition. In the caloric test, each of three patients (17.65%) showed canal paresis, an incomplete test because of severe nausea, and vomiting and hyperactive response. There were no significant differences in P1 latency, N1 latency, P1N1 amplitude, or IAR of cVEMP and oVEMP (P > 0.05). There were three patients (17.65%) and two patients (11.76%) who had abnormal IAR for cVEMP and oVEMP, respectively.CONCLUSION: Routine vestibular tests may detect some findings in only a minority of patients with seasickness.Satar B, Akin Ocal FC, Karacayli C, Coban VK. Routine vestibular tests may point out vestibular subtype of seasickness only. Aerosp Med Hum Perform. 2020; 91(11):852860.

INTRODUCTION: Environmental and operational stressors commonly encountered in spaceflight can affect astronaut cognitive performance. It is currently unclear how performance decrements on test batteries that assess individual cognitive domains translate to complex operational performance.METHODS: N 30 healthy adults (mean SD age 33.5 7.1 yr, range 2548 yr; 16 men) with demographic characteristics similar to astronauts performed all 10 tests of the Cognition test battery as well as a simulated 6 degrees-of-freedom (6df) spacecraft docking task 15 times. Performance on 60 Cognition outcome variables was rank-correlated with 6df docking performance individually as well as in models containing up to 12 predictors after accounting for sex, age, and study design effects.RESULTS: Average response time on the Digit Symbol Substitution Test (DSST)a measure of processing speed requiring complex scanning, visual tracking, and working memorywas the best individual predictor of 6df docking performance (unadjusted r 0.550; semipartial cross-validated R² 0.244). Furthermore, higher levels of spatial orientation efficiency and vigilant attention, lower levels of impulsivity, and faster response speed were associated with higher 6df performance, while sensorimotor speed, memory, and risk decision making were less relevant. After semipartial cross-validation, a model with three Cognition outcomes (DSST average response time, Abstract Matching accuracy, and conservative response bias on the Fractal 2-Back test) explained 30% of the variance in 6df performance.CONCLUSIONS: This study demonstrates direct links between performance on tests designed to assess specific cognitive domains and complex operational docking performance.Basner M, Moore TM, Hermosillo E, Nasrini J, Dinges DF, Gur RC, Johannes B. Cognition test battery performance is associated with simulated 6df spacecraft docking performance. Aerosp Med Hum Perform. 2020; 91(11):861867.

BACKGROUND: Electrocardiography (ECG) provides valuable information on astronaut physiological and psychological health. ECG monitoring has been conducted during crewed missions since the beginning of human spaceflight and will continue during astronauts upcoming long-duration exploration missions (LDEMs) in support of automated health monitoring systems. ECG monitoring is traditionally performed in clinical environments with single-use, adhesive electrodes in a 3, 6, or 12-lead configuration placed by a trained clinician. In the space exploration environment, astronauts self-place electrodes without professional assistance. Wearable ECG systems are an attractive option for automated health monitoring, but electrode placement has not been quantified to a high enough degree to avoid artifacts within the data due to position changes. This variability presents challenges for physician-limited, autonomous health monitoring, so quantifying electrode placement is key in the development of reliable, wearable ECG monitoring systems.METHODS: We present a method of quantifying electrode placement for 3-lead, chest-mounted ECG using easy-to-measure, two-dimensional chest measurements.RESULTS: We find that male and female dimensions require different electrode positioning computations, but there is overlap in positioning between men and women. The distribution of electrodes vertical positions is wider than their horizontal positions.DISCUSSION: These results can be translated directly to ECG wearable design for the individual and for the size range and adjustability required for the astronaut fleet. Implementation of this method will improve the reliability in placement and fit of future wearables, increasing comfort and usability of these systems and subsequently augmenting autonomous health monitoring capabilities for exploration medicine.Arquilla K, Leary S, Webb AK, Anderson AP. Wearable 3-lead electrocardiogram placement model for fleet sizing of medical devices. Aerosp Med Hum Perform. 2020; 91(11):868875.

INTRODUCTION: Isolated and confined environments (ICEs), such as spaceflight, are challenging psychologically. We have been evaluating self-directed tools to sustain and improve psychological well-being in these settings. The Expedition Application for Peak Psychological Performance (Expedition-APPP) is an interactive media-based set of self-directed tools that address conflict resolution, stress management, and depression treatment. Virtual reality (VR) of nature scenes is a tool to improve attention and relieve stress by providing users with an immersive nature experience. We evaluated both Expedition-APPP and VR in an ICE.METHODS: The Expedition-APP was evaluated during three, and nature VR during two, deployments at the HI-SEAS habitat, where crews of six were isolated for 812 mo. Participants used both the Expedition-APPP and VR and shared their feedback and experiences after the deployments in semistructured interviews. These interviews were evaluated using qualitative analysis techniques to gather generalizable insights into implementing autonomous mental health programs for people living and working in ICEs.RESULTS: Expedition-APPP modules provided a shared culture, language, and tools for working through challenges. VR allowed for access to emotions and experiences that were unavailable in the habitat. Suggestions for improvement included making refresher training easily available and providing a wider range of content to address different individuals coping styles.DISCUSSION: Both the Expedition-APPP and VR were appreciated and used, although a wider range of content and experiences was desired by participants.Lyons KD, Slaughenhaupt RM, Mupparaju SH, Lim JS, Anderson AA, Stankovic AS, Cowan DR, Fellows AM, Binsted KA, Buckey JC. Autonomous psychological support for isolation and confinement. Aerosp Med Hum Perform. 2020; 91(11):876885.

INTRODUCTION: We assessed determinants of serum hs-CRP level in pilots and air traffic controllers (ATCs) and its impact on their atherosclerotic cardiovascular disease (ASCVD) risk.METHODS: We obtained serum hs-CRP measurements, evaluated traditional cardiovascular risk factors and assessed global ASCVD risk based on 2018 ESH/ESC guidelines. Elevated hs-CRP was hs-CRP values > 3 mg L¹. Determinants of elevated hs-CRP were assessed using stepwise logistic regression analysis. We used the net reclassification method to evaluate the impact of hs-CRP levels on global ASCVD risk.RESULTS: Of the 335 subjects (mean age 45.4 11.6 yr, 70% pilots, 99% men, 37% Caucasians), 127 individuals (39.5%) presented with elevated hs-CRP levels. Compared to those with normal hs-CRP, individuals with elevated hs-CRP were older with faster heart rate and higher blood pressure, BMI, and P wave amplitude. The proportion of individuals with elevated hs-CRP was greater among those with smoking habits, physical inactivity, MetS, tachycardia, altered P wave axis, LVH, and HT-TOD. Aging (aOR 2.15 [1.676.98]), hypertension (aOR 3.88 [2.296.58]), type 2 diabetes (aOR 6.71 [1.7710.49]), tachycardia (aOR 2.03 [1.914.53]), and LVH (aOR 2.13 [1.647.11]) were the main factors associated with elevated hs-CRP levels. Low, moderate, high, and very high risk were observed in 24 (15%), 68 (41%), 62 (37%), and 12 (7%) subjects, respectively. Including hs-CRP resulted in the net reclassification of 25% of subjects, mostly from moderate to high risk.CONCLUSION: The integration of hs-CRP improved the estimation of global ASCVD risk stratification. However, a survey with a comprehensive population assessing the cost/benefit impact of such a referral is needed.Buila NB, Ntambwe ML, Mupepe DM, Lubenga YN, Bantu J-MB, Mvunzi TS, Kabanda GK, Lepira FB, Kayembe PK, Ditu SM, MBuyamba-Kabangu J-R. The impact of hs-CRP on cardiovascular risk stratification in pilots and air traffic controllers. Aerosp Med Hum Perform. 2020; 91(11):886891.

INTRODUCTION: This study sought to determine the incidence, severity, and time-course of simulator sickness (SS) among Asian military pilots following flight simulator training.METHODS: A survey was conducted on Republic of Singapore Air Force pilots undergoing simulator training. Each subject completed a questionnaire immediately after (0H), and at the 3-h (3H) and 6-h (6H) marks. The questionnaire included the simulator sickness questionnaire (SSQ) and a subjective scale to rate their confidence to fly.RESULTS: In this study, 258 pilots with a median age of 31.50 yr (range, 2155 yr) and mean age of 32.61 6.56 yr participated. The prevalence of SS was 48.1% at 0H, 30.8% at 3H, and 16.4% at 6H. Based on a threshold of an SSQ score >10, the prevalence of operationally significant SS was 33.3% at 0H, 13.2% at 3H, and 8.1% at 6H. The most frequent symptoms were fatigue (38.1%), eye strain (29.0%), and fullness of head (19.9%). There was no significant difference in mean scores between rotary and fixed wing pilots. Older, more experienced pilots had greater scores at 0H, but this association did not persist. A correlation was found between SSQ score and self-reported confidence.DISCUSSION: To our knowledge, this study is the first to report the prevalence of operationally significant SS in Asian military pilots over serial time points. Most pilots with SS are able to subjectively judge their fitness to fly. Sensitivity analysis suggests the true prevalence of SS symptoms at 3H and 6H to be closer to 23.8% and 12.0%, respectively.Loi JEQ, Lee MLL, Tan BBC, See B. Time course of simulator sickness in Asian military pilots. Aerosp Med Hum Perform. 2020; 91(11):892896.

INTRODUCTION: Mental health is an important aspect of Army aviation medicine given that it significantly impacts career longevity, readiness, and healthcare usage. One of the most commonly used classes of medications to treat mental health disorders is the selective serotonin reuptake inhibitor (SSRI). Here we present a descriptive epidemiological review of SSRI use in Army aviators over a 10-yr period.METHODS: An archival dataset retrieved from the U.S. Army Aeromedical Electronic Resource Office covering the years 2005 to 2015 was queried for cases of SSRI use. Frequencies were generated by primary diagnoses and aeromedical disposition for the SSRI subset of data.RESULTS: A total of 114 unique cases of SSRI use were identified (122 total aeromedical outcomes). These cases included 41 waiver recommendations, 59 suspension recommendations, and 22 cases of waiver continuations. The top five most common primary diagnoses were depressive disorder (N 32), anxiety state (N 21), posttraumatic stress disorder (N 16), single major depressive episode (N 13), and adjustment disorder with depressed mood (N 12).DISCUSSION: Understanding of the etiology, pathophysiology, and treatment of mental health disorders particularly within the safety-focused and unforgiving aviation environment has continued to evolve. With the application of evidence-based policy, deliberate aeromedical decision-making, and methodical risk mitigation, SSRI use does have a place within aviation. Aviators suffering in silence with deleterious impact to performance and safety or aircrew seeking services on the outside without knowledge or oversight of certification authorities must remain in the past.Kelley AM, Bernhardt K, McPherson M, Persson JL, Gaydos SJ. Selective serotonin reuptake inhibitor use among Army aviators. Aerosp Med Hum Perform. 2020; 91(11):897900.

BACKGROUND: Rhabdomyolysis is a potentially fatal disease caused by trauma, infections, and toxins. Rhabdomyolysis has not been reported in Chinese civil aircrew, but in our case report a male civil copilot contracted rhabdomyolysis after excessive exercise, showing potential for morbidity in pilots.CASE REPORT: After excessive exercise, a 29-yr-old male civil aviation copilot complained of serious myalgia and weakness in lower limb muscles and gross hematuria, whose values of alanine transaminase (ALT), aspartate transaminase (AST), myohemoglobin (Mb), creatine kinase (CK), CK-MB, lactate dehydrogenase (LDH), and -hydroxybutyrate dehydrogenase (-HBDH) were conspicuously increased. Magnetic resonance imaging showed abnormal signal intensities in the lower limbs. The patient was diagnosed with rhabdomyolysis. He was treated with hydration and urine alkalinization. When his condition was stabilized, the patient was discharged. After remaining asymptomatic for 3 mo and getting documentation of normalized lab results, he was granted a first-class medical certificate and returned to work.DISCUSSION: This was the first case of rhabdomyolysis reported in Chinese civil aircrew. Excessive exercise in an overweight pilot may induce rhabdomyolysis. This condition can be controlled and cured by early and effective treatment. Rhabdomyolysis could occur in a population suffering from overweight, obesity, or hyperlipidemia. This case fits in with several other cases of military pilots exercising excessively. The progression could lead to acute kidney injury without prompt and effective intervention. And common symptoms like muscular weakness or myalgia may induce sudden in-flight incapacitation, so early medical intervention should be adopted. Moreover, recurrence of rhabdomyolysis should be considered when resuming flying duties.Liu X, Meng X, Zhang C, Chen J, Li P, Wu X, Fan H. Rhabdomyolysis in a civil aviation pilot. Aerosp Med Hum Res. 2020; 91(11):901903.

BACKGROUND: Spontaneous vitreous hemorrhage is uncommon in the general population. Of cases, 1020% are idiopathic or due to occult causes and a majority of the remainder are associated with diabetic disease. The evaluation and disposition of an aviator has not been reported previously. This case will document the work-up and safe return to flight of a patient.CASE REPORT: A 33-yr-old male MH-60R pilot presented with acute blurred vision in the left eye and eye pain which began at his desk. His review of systems was otherwise negative. His medical history was noncontributory. On initial examination his vital signs and external ocular exam were normal. He was immediately referred to the optometry clinic, where a dilated funduscopic examination (DFE) with scleral depression demonstrated a large floater OS composed of streaks of blood and tobacco dust. His DFE was otherwise normal with no retinal tears or vitreous detachments. On repeated DFEs, his intraoccular pressures remained normal and his hemorrhage resorbed without decreased visual acuity or field deficits. A hematologic work-up was negative. After 4 mo of observation, the patient was returned to flight status without further recurrence.DISCUSSION: No known associations exist between aeronautical duties and spontaneous vitreous hemorrhages. The stressors aviators are subjected to, such as high vibrations and increased g forces, may make them more likely to suffer intraocular microvascular damage that could lead to retinal detachment, vitreous detachment, and bleeding. Further reports are needed to determine the risks of recurrence in aviators and their differences from typical spontaneous vitreous hemorrhage patients.Wallace SA. Spontaneous vitreous hemorrhage in a naval aviator. Aerosp Med Hum Perform. 2020; 91(11):904907.