Cognitive performance of air personnel following sleep deprivation.

Air forces have developed several methods for reducing fatigue-related accidents. In the Israeli Air Force, the "Dead Tired" workshop was developed with the purpose of presenting aircrew with their objective performance under sleep deprivation conditions. The aim of this study was to examine the cognitive abilities of both aircrew and unmanned aerial vehicle operators, both objectively and subjectively. All Israeli aircrew and unmanned aerial vehicle operators participated in a "Dead Tired" workshop. During the workshop, the participants performed the Psychomotor Vigilance Task, a task that tests their attention abilities, while gathering information on their subjective sleepiness in the form of a Karolinska Sleepiness Scale. Data of 366 participants (25 females), of whom 187 were unmanned aerial vehicle operators and 179 were aircrew, were obtained; and the mean age was 21.8 ± 1.2 years (range 19-26 years). A significant decline in task performance was seen following 20 hr of wakefulness in both unmanned aerial vehicle operators and aircrew (p < 0.001). Unmanned aerial vehicle operators' performance was significantly better throughout the majority of the workshop (p < 0.001). Recovery after the full-night's sleep was seen for unmanned aerial vehicle operators, but not for aircrew (p = 0.008). A high correlation was seen between Psychomotor Vigilance Task performance and Karolinska Sleepiness Scale responses (correlation coefficient = 0.93). Sleep deprivation negatively impacted the performance of both groups of participants. Unmanned aerial vehicle operators were found to be more resilient to the effects of sleep deprivation and were quicker to recover in comparison to aircrew.

Subjective versus objective refraction in healthy young adults.

PURPOSE: To evaluate objective and subjective refraction differences in healthy young adults. METHODS: Data concerning candidates for the Israeli Air Force Flight Academy, as well as active air force pilots in all stages of service who underwent a routine health checkup between the years 2018 and 2019 were retrospectively analyzed. Objective refraction measured using a single autorefractometer was compared with subjective refraction measured by an experienced military optometrist during the same visit. The results were converted to power vectors (spherical equivalent [SE], J0, and J45). To interpret astigmatism using power vector values, the cylinder power (Cp) was determined. RESULTS: This study included 1,395 young adult participants. The average age was 22.17 years (range, 17-39, 84.8% males). The average SE was - 0.65 ± 1.19 diopter (D) compared with - 0.71 ± 0.91D in the auto- and subjective refraction, respectively (p = 0.001). Cp was 0.91 ± 0.52D and 0.67 ± 0.40D, respectively (p < 0.001). This difference was more common in older participants (p < 0.001). J0 and J45 value differences were not significant. The absolute SE value of subjective refraction was lower in the myopic (p < 0.001) and hyperopic (p < 0.001) patients. CONCLUSIONS: Young hyperopic participants tended to prefer "less plus" in subjective refraction compared with autorefraction. Young myopic participants tended to prefer "less minus" in subjective refraction compared with autorefraction. All participants, but mainly older participants, preferred slightly "less Cp" than that measured using autorefraction; The astigmatic axis did not differ significantly between the methods.

Facial and trigeminal nerves neuropathy induced by atmospheric pressure changes: A meta-analysis.

BACKGROUND: Barometric pressure changes during flight or diving may cause facial barotrauma. Neuropathy of the fifth (CN5) or the seventh (CN7) cranial nerves is a rare manifestation of this condition. The aim of this study was to analyze risk factors for baroneuropathies of CN5 and CN7. METHODS: A search of PubMed and Cochrane Library databases was conducted to identify all published cases of CN5 and CN7 neuropathies. Only original case reports and series that documented events of neuropathies associated with the trigeminal nerve or facial nerve while flying, diving, or mountain climbing were included. Assessed variables included sex, medical history, age, setting (flight or diving), atmospheric pressure changes, number of episodes, symptoms, treatment, and recovery. RESULTS: We identified a total of 48 articles described >125 episodes in 67 patients. Mean age was 33.5 ± 12.1 years with a male predominance (76.1 %). Cases were equally distributed between flight and diving (50.7 %, 46.3 %, respectively). CN5 involvement was observed in 77.6 % of patients, with ear pain and facial numbness as the most common symptoms. The latter was correlated with positive otolaryngology medical history. CN7 was involved in 88.1 % of patients. Flying, as opposed to diving was correlated with spontaneous resolution of symptoms (86.7 % vs. 42.3 % of cases resolved spontaneously, respectively, p = 0.001). CONCLUSIONS: Flight is an equal risk factor to diving with respect to CN5 and CN7 barotrauma. Involvement of CN7 was observed in most cases, but possibly due to report-bias. Positive medical history is a risk factor for facial numbness.

Simulator sickness among helicopter pilots: Incidence, threshold and severity using the SSQ.

BACKGROUND: Flight simulators have an essential role in aircrew training. Occasionally, symptoms of motion sickness, defined as simulator sickness, develop during training sessions. The reported incidence of simulator sickness ranged widely in different studies. OBJECTIVE: The aims of this study were to calculate the incidence of and to define a threshold value for simulator sickness among rotary-wing pilots using the validated Simulator Sickness Questionnaire (SSQ). METHODS: CH-53 and UH-60 helicopter pilots, who trained in helicopter simulators in the Israeli Air Force, were asked to fulfill SSQ. A score of 20 in the SSQ was defined as the threshold for simulator sickness. Simulator sickness incidence and average SSQ were calculated. Correlations between age and simulator training hours to SSQ scores were analyzed. RESULTS: A total of 207 rotary-wing aircrew participated in the study. Simulator sickness was experienced by 51.7% of trainees. The average SSQ score was 32.7. A significant negative correlation was found between age and SSQ score. CONCLUSIONS: Simulator sickness was experienced by more than half of helicopter pilots. A score of 20 in the SSQ was found to be suitable as the threshold for this condition.

Smartphone-based hearing test as an aid in the initial evaluation of unilateral sudden sensorineural hearing loss.

Sudden sensorineural hearing loss (SSNHL) can cause significant morbidity. Treatment with steroids can improve outcome. Delay in initiation of treatment reduces the chance to regain hearing. For this reason SSNHL is considered an emergency. Diagnosis is based on history, physical examination and a standard audiogram, the latter requiring specialized equipment and personnel. Standard audiogram may not be available at the time and place of patient presentation. A smartphone or tablet computer-based hearing test may aid in the decision to prescribe steroids in this setting. In this study the uHear™ hearing test application was utilized. The output of this ear-level air conduction hearing test is reported in hearing grades for 6 frequencies ranging from 250 to 6000 Hz. A total of 32 patients with unilateral SSNHL proven by a standard audiogram were tested. The results of standard and iPod hearing tests were compared. Based on the accepted criterion of SSNHL (at least 30 dB loss - or 2 hearing grades - in 3 consecutive frequencies) the test had a sensitivity of 0.76 and specificity of 0.91. Using a less stringent criterion of a loss of 2 hearing grades over at least 2 frequencies the sensitivity was 0.96 and specificity 0.86. The correlation coefficient for the comparison of the average hearing grade across the 6 measured frequencies of the study and standard audiogram was 0.83. uHear more accurately reflected hearing thresholds at mid and high tones. Similarly to previously published data, low frequency thresholds could be artificially elevated. In conclusion, uHear can be useful in the initial evaluation of patients with single-sided SSNHL by providing important information guiding the decision to initiate treatment before a standard audiogram is available.

Anticholinergic Versus Antihistaminic Treatment for Simulator Sickness Prevention.

Flight simulators have an essential role in aircrew training. Occasionally, symptoms of motion sickness, defined as simulator sickness, develop during these sessions. Preventive methods for motion sickness have been investigated thoroughly; however, only a few studies have examined preventive treatments for simulator sickness. The aim of this study was to examine the efficacy of scopolamine (an anticholinergic drug) compared with cinnarizine (an antihistaminic drug) for helicopter simulator sickness prevention. A validated simulator sickness questionnaire (SSQ) score was used to determine the severity of simulator sickness symptoms in this study. Preliminary SSQ scores and SSQ scores after each sortie were calculated. Each participant was given scopolamine, cinnarizine, or a placebo in a double-blind randomized manner before the first sortie of each training day. Forty-one helicopter pilots participated in the trial. The average age was 30.5 ± 7.1 years. SSQ values significantly improved from an average of 73.30 in the preliminary SSQ questionnaire to an average of 30.92 after 2 hours following the administration of cinnarizine (P = .012, 95%CI 8.071-76.703). Scopolamine was found to be less effective than both cinnarizine and the placebo in the alleviation of simulator sickness symptoms. This study is the first to compare scopolamine with cinnarizine for simulator sickness prevention. Based on the results of this study, we recommend the use of cinnarizine over scopolamine for simulator sickness prevention.

Negative impact of high-performance flights on aviators with mitral valve prolapse.

BACKGROUND: While it appears not to affect healthy aviators' hearts, there are scarce data regarding the impact of high-performance flights on aviators with mitral valve prolapse (MVP). METHODS: A retrospective, comparative cohort study of military aviators with MVP. Subjects were categorized to either high-performance (jet fighter) or low-performance (transport and helicopter) aviators. The primary outcomes were the rates of mitral interventions and of adverse cardiovascular events since being an aircrew candidate and up to the end of flying career. Additional outcomes were echocardiographic measurements and the cumulative proportion of mitral valve interventions over time. RESULTS: Of 33 male aviators with MVP, 18 were high-performance aviators. On average, follow-up started at age 18.5 years and lasted 27.8 ±â€¯10.1 years. Baseline characteristics were similar between the study groups. Aviators of high-performance aircraft had increased rates of mitral valve surgery (33 % vs. 0, p = 0.021), MVP-related complications (39 % vs. 6.7 %, p = 0.046), and a higher incidence of mitral valve repair over time (p = 0.02). High-performance flight was associated with increased intraventricular septum thickness (IVS, 9.7 mm vs 8.9 mm, p = 0.015) and IVS index (p = 0.026) at the last echocardiographic assessment. High-performance aviators tended to develop worsening severity of mitral regurgitation. CONCLUSIONS: High-performance flight may be associated with an increased risk for valvular deterioration and need for mitral surgery in aviators with MVP.

Mitigating Risks of Altitude Chamber Training.

INTRODUCTION: Altitude chambers are used for training aircrews in a hypobaric hypoxic environment to better prepare them for pressurization and oxygen malfunction incidents during flights. However, adverse effects may occur during training sessions, with decompression sickness (DCS) being a major concern. The aim of this study was to examine the risks of different adverse effects during altitude chamber trainings (ACT) in the Israeli Air Force (IAF) facility and to compare them to other training facilities.METHODS: We retrospectively reviewed the records of 1627 individuals in the IAF who were trained in the altitude chamber between 2015 and 2019. Data regarding adverse effects and training safety were extracted. Literature review of altitude chamber trainings was performed and adverse effects rates were compared.RESULTS: There were a total of 91 adverse effects cases in the IAF during the study period. The overall risk rate for an adverse effect was 5.59%. The most common adverse effect was middle ear and sinus barotrauma (69.3% of adverse effects cases), followed by breathing problems (14.3%) and DCS cases (9.9%).CONCLUSIONS: Mitigating the risk for DCS should be major concern during ACT. We recommend setting a standard protocol for an ACT which includes a 45-min preoxygenation period, a maximal ascent rate of 3000 ft · min-1 (914 m · min-1), and setting a maximum altitude of 25,000 ft (7620 m) for fixed-wing trainees.Nakdimon I, Ben-Ari O. Mitigating risks of altitude chamber training. Aerosp Med Hum Perform. 2022; 93(11):811-815.

Return to Flying Duties Following a COVID-19 Booster Dose.

INTRODUCTION: Israel began vaccinating with the booster dose of the Pfizer-BioNTech vaccine in July 2021, before the Food and Drug Administration (FDA) authorized the vaccine in September 2021. The first and second vaccines were shown to have several side effects that could possibly affect aircrews' fitness to fly. Thus, the Israel Air Force (IAF) decided on a disqualification period of 24 h following the first vaccine, and 48 h following the second vaccine. The aim of this study was to determine the disqualification period following the booster dose of the vaccine.METHODS: A survey was conducted among IAF aviators in the Aeromedical Center (AMC) in order to characterize the side effects and their duration following a Pfizer-BioNTech COVID-19 vaccine booster dose.RESULTS: The most common local side effect was injection site pain. The most common systemic side effects were general weakness, fatigue, and myalgia. Duration of side effects was up to 48 h from vaccine administration among the majority of aircrew members.CONCLUSION: The IAF AMC policy for the Pfizer-BioNTech COVID-19 vaccine booster dose recipients is to disqualify from flight for 48 h following the vaccination.Ekshtein A, Hay G, Shapira S, Ben-Ari O. Return to flying duties following a COVID-19 booster dose. Aerosp Med Hum Perform. 2022; 93(7):593-596.

The influence of refractive state and heterophorias on visual acuity and stereoacuity in healthy young adults.

PURPOSE: To evaluate associations of refractive error and heterophoria with best-corrected visual acuity and stereoacuity in a population of healthy young adults. METHODS: Data extracted from the Israeli Defense Forces Air Force candidates database was analyzed retrospectively. Myopia and hyperopia were defined as spherical equivalent of ≤ -0.50 D and ≥ +0.50 D. Cylinder of ≥0.75 D was considered astigmatism. Oblique astigmatism was defined as axis between 30°-60° and 120°-150°. Heterophoria of ≥8Δ for near was considered exo- or esophoria. RESULTS: The study population included 5,491 subjects (75.8% male), with a mean age of 17.6 ± 0.9 years: 2,355 (42.9%) had myopia, 640 (11.6%) had hyperopia, and the rest were emmetropic. Astigmatism was present in 2,006 participants (36.5%), and of those, 619 (30.9%) had oblique astigmatism. Emmetropia was correlated with better best-corrected visual acuity; astigmatism and high hyperopia, with poorer best-corrected visual acuity. A total of 331 subjects (6%) had heterophoria of ≥8Δ; of those, 300 (90.6%) had exophoria and 31 (9.4%) had esophoria. The prevalence of exophoria was higher in the myopic group, and exophoria was not associated with stereoacuity. Esophoria and anisometropia were associated with worse stereoacuity. The best stereopsis was achieved by emmetropic subjects with no astigmatism. CONCLUSIONS: Emmetropia is associated with better best-corrected visual acuity and stereoacuity. Astigmatism and high hyperopia are correlated with poorer best-corrected visual acuity. Exophoria does not interfere with stereopsis, but both esophoria and anisometropia do.