INTRODUCTION: There have been few large-scale epidemiological examinations of military aircrew populations reported in recent literature. This study examined 10 yr of medical records contained in the U.S. Army Aeromedical Electronic Resource Office (AERO) in an effort to identify the most prevalent conditions affecting Army aviator career longevity.METHODS: This study was a retrospective epidemiological review; data were retrieved on 24,568 rated aircrew patients from the AERO database, of whom 5.2% were women. The dataset was composed of a total of 181,471 cases between June 2005 and June 2015. Age ranged from 17 to 73 yr. The data were examined in terms of raw ICD-9 diagnostic codes, derived systems-based categories, and occupational consequences.RESULTS: The top 10 diagnoses, causes for waiver, and permanent suspension of aircrew were determined both in terms of the ICD-9 codes and the system groupings. Leading waiver causes included hypertension (11.5%), hearing loss (9.7%), spinal disorder (14.4%), and obstructive sleep apnea (5.2%). Leading permanent suspension causes were psychiatric disorders (28.2%), particularly PTSD, being the leading cause, with spinal pathology (16.1%) second. In almost all diagnostic groupings the Spearman’s rho correlation coefficients between age and diagnosis presence were positively related, although often with no association with negative occupational outcome.DISCUSSION: This study revealed the leading medical causes of waiver and suspension from flying duties, producing evidence to inform leadership understanding of disease prevalence and its subsequent impact on flying status. This is of prime importance to help direct policy and implement strategies for health protection.Curry IP, Kelley AM, Gaydos SJ. Clinical diagnoses leading to suspension in Army aircrew: an epidemiological study. Aerosp Med Hum Perform. 2018; 89(7):587–592.

INTRODUCTION: The greater sensitivity of extended high-frequency audiometry (EHFA) than conventional audiometry (CA) for identifying early changes in hearing has been well documented in previous literature. However, no studies about EHFA were conducted on civilian pilots. The aim of this study was to investigate the usefulness of EHFA as an assay to evaluate civilian pilots’ hearing status.METHODS: An observational cross-sectional study was conducted on 134 civilian pilots (case group) and 101 subjects without noise exposure (control group). All of the subjects underwent CA (0.25–8 kHz) and EHFA (9–20 kHz). The potential of EHFA for identifying early changes in hearing was assessed.RESULTS: The two audiometric tools both showed significantly higher hearing thresholds in the case group for most of the frequencies tested, but the differences were more obvious for EHFA. Compared with the control group, the average thresholds in the case group increased 3.15 dB at CA and 7.83 dB at EHFA for age 20–29. The number was 2.37 dB and 9.90 dB for age 30–39; 3.80 dB and 8.19 dB for age 40–49; and 10.84 dB and 16.86 dB for age 50–59. There were 74.6% of pilots who had hearing loss in at least in one ear and at one frequency in CA and 94.8% at EHFA. Significant differences in EHFA were observed also between pilots and their controls with normal hearing thresholds at CA.CONCLUSIONS: EHFA is more sensitive than CA and could be useful in detecting subclinical changes of hearing in civilian pilots.Ma F, Gong S, Liu S, Hu M, Qin C, Bai Y. Extended high-frequency audiometry (9–20 kHz) in civilian pilots. Aerosp Med Hum Perform. 2018; 89(7):593–600.

INTRODUCTION: We examined whether long-haul airline pilots without recurrent on-duty sleepiness obtain more prior sleep and use more effective in-flight alertness management strategies than their colleagues with recurrent on-duty sleepiness.METHODS: There were 51 pilots who flew at least twice from Helsinki to Asia. Of them, 44 flew at least twice back to Helsinki following 1 local night. On-duty sleepiness was measured by the Karolinska Sleepiness Scale (KSS), alertness management strategies by a diary, and sleep by a diary and activity monitor. Pilots who rated KSS ≥ 7 on each, some, or none of the flights were classified as ”regularly”, “sometimes”, and “never” sleepy, respectively. This classification was performed separately for the outbound and inbound flights.RESULTS: On the outbound flights, 22% of the pilots were “never”, 54% “sometimes”, and 24% “regularly” sleepy. For the inbound flights, the respective distribution was 25%, 48%, and 27%. Compared to the “regularly” sleepy group, the “never” sleepy group obtained 54 min more night sleep prior to the outbound flights. For the inbound flights, the respective difference was 1 h 23 min. Also, the “never” sleepy pilots slept 31 min more between days off than the ”regularly” sleepy pilots. The results of the in-flight alertness management strategies were mixed.DISCUSSION: The study demonstrates that pilots without recurrent on-duty sleepiness obtain more sleep than their colleagues with recurrent on-duty sleepiness. The result emphasizes the need to investigate whether the sleep of recurrently sleepy pilots can be increased and whether this increase would reduce their on-duty sleepiness.Sallinen M, Åkerstedt T, Härmä M, Henelius A, Ketola K, Leinikka M, Kecklund G, Sihvola M, Tuori A, Virkkala J, Puttonen S. Recurrent on-duty sleepiness and alertness management strategies in long-haul airline pilots. Aerosp Med Hum Perform. 2018; 89(7):601–608.

INTRODUCTION: Sleep loss can result in cognitive, motor, and neurobehavioral impairments. In an aviation context, this can cause a serious threat to flight safety. Therefore, the study aimed to investigate the effects of 24-h sleep deprivation on mood, fatigue, and airline pilot competencies.METHODS: Seven subjects attended two 24-h testing periods, one with an 8-h sleep opportunity, and the other with no sleep opportunity (i.e., sleep deprivation). Subjects were required to complete a battery of mood, fatigue, and analogue measures of pilot competency tasks every 8 h (0 h, 8 h, 16 h, 24 h) throughout each testing period.RESULTS: While total mood disturbance was found to significantly increase (83.42, SD = 25.7), both objective (352.71, SD = 42.00) and subjective (34.85, SD = 8.82) fatigue were found to significantly decrease following 24-h sleep deprivation. Cognitive flexibility (757.45, SD = 58.48) and hand-eye coordination (dominant hand only) (60.28, SD = 3.86) were also negatively impacted following 24-h sleep deprivation. However, working memory and situation awareness were not significantly negatively impacted by the bout of sleep deprivation.DISCUSSION: Some pilot-specific task-related factors such as subjective fatigue, cognitive flexibility, and working memory were found to be particularly susceptible to sleep loss, with significant declines in performance observed following 16-h continuous wakefulness, suggesting reductions in optimal functioning following this period of wakefulness. Further investigation using more regular testing time points, employing additional pilot competencies, and using more aviation-specific tasks is warranted.O’Hagan AD, Issartel J, McGinley E, Warrington G. A pilot study exploring the effects of sleep deprivation on analogue measures of pilot competencies. Aerosp Med Hum Perform. 2018; 89(7):609–615.

BACKGROUND: Chromosome translocations are a biomarker of cumulative exposure to ionizing radiation. We examined the relation between the frequency of translocations and cosmic radiation dose in 83 male airline pilots.METHODS: Translocations were scored using fluorescence in situ hybridization chromosome painting. Cumulative radiation doses were estimated from individual flight records. Excess rate and log-linear Poisson regression models were evaluated.RESULTS: Pilots’ estimated median cumulative absorbed dose was 15 mGy (range 4.5–38). No association was observed between translocation frequency and absorbed dose from all types of flying [rate ratio (RR) = 1.01 at 1 mGy, 95% confidence interval (CI) 0.97–1.04]. However, additional analyses of pilots’ dose from only commercial flying suggested an association (RR = 1.04 at 1 mGy, 95% CI 0.97–1.13).DISCUSSION: Although this is the largest cytogenetic study of male commercial airline pilots to date of which the authors are aware, future studies will need additional highly exposed pilots to better assess the translocation-cosmic radiation relation.Grajewski B, Yong LC, Bertke SJ, Bhatti P, Little MP, Ramsey MJ, Tucker JD, Ward EM, Whelan EA, Sigurdson AJ, Waters MA. Chromosome translocations and cosmic radiation dose in male U.S. commercial airline pilots. Aerosp Med Hum Perform. 2018; 89(7):616–625.

BACKGROUND: Understanding human behavior under the effects of sleep deprivation allows for the mitigation of risk due to reduced performance. To further this goal, this study investigated the effects of short-term sleep deprivation using a tilt-based control device and examined whether existing user models accurately predict targeting performance.METHODS: A task in which the user tilts a surface to roll a ball into a target was developed to examine motor performance. A model was built to predict human performance for this task under various levels of sleep deprivation. Every 2 h, 10 subjects completed the task until they reached 24 h of wakefulness. Performance measurements of this task, which were based on Fitts’ law, included movement time, task throughput, and time intercept.RESULTS: The model predicted significant performance decrements over the 24-h period with an increase in movement time (R² = 0.61), a decrease in throughput (R² = 0.57), and an increase in time intercept (R² = 0.60). However, it was found that in experimental trials there was no significant change in movement time (R² = 0.11), throughput (R² = 0.15), or time intercept (R² = 0.27).DISCUSSION: The results found were unexpected as performance decrement is frequently reported during sleep deprivation. These findings suggest a reexamination of the initial thought of sleep loss leading to a decrement in all aspects of performance.Bolkovsky JB, Ritter FE, Chon KH, Qin M. Performance trends during sleep deprivation on a tilt-based control task. Aerosp Med Hum Perform. 2018; 89(7):626–633.

BACKGROUND: Motion sickness is a serious issue for many individuals, but the problem is particularly important among military personnel who may regularly experience unusual or extreme motion profiles as a part of their duties. As such, it is important to understand the underlying mechanisms that contribute to motion sickness, which in turn can lead to new and more effective countermeasures. The current study investigated causal etiology by examining the predictions of postural instability theory. Subjects experienced multiple motion profiles while reporting their sickness symptoms.METHODS: Postural instability was directly manipulated by including both an active and passive condition. In the active condition, subjects could actively adapt their posture to the motion profile. In the passive condition, subjects had their feet affixed in place and could not effectively adapt their posture to the motion profiles. Subjects completed both conditions to control for individual differences in motion sickness susceptibility.RESULTS: Active condition subjects had greater postural stability as measured by sample entropy (M = 0.179 Active, M = 0.136 Passive), and sickness symptoms increased with time. Both results provide a methodological check against our manipulation. However, there were no differences in symptoms between active or passive conditions as measured by the simulator sickness questionnaire (M = 16.56 and M = 18.25, respectively), and no relationship between our measure of postural instability and symptomology.DISCUSSION: These results do not support postural instability as the primary causal factor in motion sickness; however, more research is needed to elucidate the mechanisms of motion sickness etiology.Pettijohn KA, Geyer D, Gomez J, Becker WJ, Biggs AT. Postural instability and simulator seasickness. Aerosp Med Hum Perform. 2018; 89(7):634–641.

BACKGROUND: The purpose of this work was to investigate the brain’s rhythmic activity during a simulated microgravity condition (namely dry immersion).METHODS: During dry immersion, which lasted for 5 d, nine subjects (healthy men, 20 to 29 yr of age) were individually placed in a tub (2.2 × 1.1 × 0.85 m) filled with water (temperature was kept constant at about 33°C). Subject floated in the tub without bodily support in the supine horizontal position, but isolated from the water by waterproof material. Resting state EEGs were registered at the fourth or fifth day of dry immersion. Under the control conditions, resting state EEGs were registered while subjects laid in a supine position on a couch.RESULTS: Compared to the control condition, EEG power in the alpha range (8–13 Hz) was greater in dry immersion; this effect was distributed across the whole scalp. No effects of dry immersion were found for the beta, delta, or theta frequency bands.CONCLUSION: The results of the study, similar to those obtained in a real spaceflight, indicate that support withdrawal is an important contributor to brain activity alterations in weightlessness.Lazarev IE, Tomilovskaya ES, Kozlovskaya IB. Resting state brain activity during long-term dry immersion. Aerosp Med Hum Perform. 2018; 89(7):642–647.

BACKGROUND: This study aims to examine which marker or testing protocols have been suggested for cardiovascular disease (CVD) risk assessment in asymptomatic populations, at which CVD risk level, and how this can be implemented for CVD risk assessment in pilot populations.METHODS: A systematic search was performed using Systematic Reviews Subset on PubMed; the OvidSP interface, including all EBM reviews and EMBASE databases; and the G-I-N International Guideline Library. From each recommendation, we extracted data on consideration of the use of a marker or test for cardiovascular risk assessment in asymptomatic populations.RESULTS: Included were 45 guidelines, systematic reviews, or meta-analyses relevant to cardiovascular risk assessment in asymptomatic populations. The majority (9/12) of the citations recommend coronary artery calcium score (CACS) for CVD risk assessment in intermediate-risk (10-yr CVD risk score of 10–20%) asymptomatic adults. Other cardiac and vascular tests that may also be considered include the measurements of carotid-intima media thickness, supplemented by carotid plaque, and the ankle brachial index for prevention of peripheral artery disease and stroke. Stress myocardial perfusion scan is the potential cardiac functional test to be used with pilots with 5-yr risk of ≥15%. Among laboratory markers, only hs-CRP has a potency to be used in CVD risk assessment in intermediate-risk asymptomatic adults; however, the strength of the recommendation is not adequate.DISCUSSION: Among the cardiac and vascular testing available, CACS is the most frequently suggested test. The implications of findings for CVD risk assessment in airline pilots are highlighted in this paper.Wirawan IMA, Griffiths RF, Larsen PD. Cardiovascular tests for risk assessment in asymptomatic adults and implications for pilots. Aerosp Med Hum Perform. 2018; 89(7):648–656.

BACKGROUND: Supraventricular tachycardia (SVT) is a common presenting arrhythmia in the general population. Cases of SVT presenting during commercial air travel are always challenging as they might be confused with other conditions requiring different treatment strategies. We present a case of an in-flight SVT that was successfully managed using telemedicine support.CASE REPORT: A 33-yr-old woman developed chest pain and dizziness while on an international commercial flight. Vital signs obtained on an on-board telemedicine device recorded an initial heart rate and blood pressure of 220 bpm and 128/78 mmHg, respectively. An electrocardiogram (ECG) was also obtained and transmitted to the ground-based medical support (GBMS) center where an SVT was diagnosed. Vagal maneuvers were recommended which resulted in a return to sinus rhythm and stabilization of the patient.DISCUSSION: In parallel to the global increase in commercial air travel, it is expected that the incidence of in-flight arrhythmias will also increase, including SVTs. Vagal maneuvers are a safe, first-line option. While treating patients with a symptomatic tachyarrhythmia it is essential to diagnose the underlying arrhythmia, especially when initial maneuvers fail. Telemedicine, with transmission of vital signs and ECGs to GBMS centers, can enable diagnosis and guide management of in-flight SVTs, distinguishing them from other forms of cardiac arrhythmia. Undifferentiated chest pain and dizziness are common causes for flight diversions and, as such, could potentially be prevented in some instances by using telemedicine.Voerman JJ, Hoffe ME, Surka S, Alves PM. In-flight management of a supraventricular tachycardia using telemedicine. Aerosp Med Hum Perform. 2018; 89(7):657–660.

BACKGROUND: Otitis externa secondary to irritant or chemical exposure is well documented; however, specifically secondary to jet fuel exposure and its associated toxicology is not. Over 2 million military and civilian personnel per year are occupationally exposed to aviation fuels.CASE REPORT: An aircraft maintainer presented with noninfectious acute otitis externa secondary to external ear canal exposure to JP-5 jet fuel. Proper exposure guidelines were followed, but it was not realized that the external ear canal was involved. The first symptoms to emerge were vertigo, dizziness, and disequilibrium; however, on physical exam it appeared that there was no middle ear involvement.DISCUSSION: Otitis externa normally does not present with vestibular symptoms as the pathology affects the external ear canal dermal tissue. Upon review of JP-5’s toxicology profile, dermal absorption is a route of entry and can cause general neurological symptoms, including loss of coordination. This case highlights potential deficiencies in the standardized safety data sheets that are used after exposure. Without mention of possible auricular exposure one may focus on the logical protection of the eyes, mouth, and visible skin. This is concerning due to potential delayed exposure symptoms, dermal absorption, high level of dermal destruction, and the close proximity to the sensory system. The goal of this case report is to improve the knowledge of providers caring for personnel who may be exposed and to suggest possible revisions to the Safety Data Sheets for jet fuel.Long RJ, Charles RA. Aviation fuel exposure resulting in otitis externa with vertigo. Aerosp Med Hum Perform. 2018; 89(7):661–663.

Vu PD. You’re the flight surgeon: nephrolithiasis. Aerosp Med Hum Perform. 2018; 89(7):664–667.