BACKGROUND: The vestibulo-sympathetic reflex operates during orthostatically challenging movements to initiate cardiovascular responses in advance of a baroreceptor-mediated response. The objective of this study was to determine whether there was an association between changes in vestibular function and cardiovascular responses during a prone-to-stand movement in astronauts after return from long-duration spaceflight.METHODS: Thirteen crewmembers who participated in International Space Station missions were tested before spaceflight and 1 d after landing. Vestibular function was evaluated by computerized dynamic posturography while their head was erect and while they performed dynamic head tilts. Heart rate and mean arterial blood pressure were measured while the subjects were in prone and standing positions.RESULTS: The 21.4% increase in the astronauts’ heart rate during the prone to stand maneuver after spaceflight correlated significantly with their spaceflight-induced 48.7% decrease in postural stability during dynamic head tilts. The larger mean arterial pressure in the prone position after spaceflight compared to preflight (+7%) also correlated with the postflight decrease in postural stability during dynamic head tilts.CONCLUSION: These results indicate that an appropriate vestibular function is important to evoke optimum vestibulo-sympathetic response during orthostatically challenging voluntary movements performed after spaceflight. They also suggest that there may be a greater need to generate an anticipatory cardiovascular response after spaceflight.Deshpande N, Laurie SS, Lee SMC, Miller CA, Mulavara AP, Peters BT,Reschke MF, Stenger MB, Taylor LC, Wood SJ, Clément GR, Bloomberg JJ. Vestibular and cardiovascular responses after long-duration spaceflight. Aerosp Med Hum Perform. 2020; 91(8):621–627.

INTRODUCTION: We examined aircrew fatigue during the following flight duty periods (FDPs) mentioned in the European Union (EU) Flight Time Limitations (FTLs): night FDPs longer than 10 h and FDPs typical of disruptive schedules (early starts, late finishes, and nights). An alternative way of classifying night FDPs was also examined to reveal possible subcategories that warrant special attention.METHODS: A total of 392 aircrew members (96 women) representing 24 airlines participated in the study. Their FDPs were measured by a diary, sleep by the diary and wrist-actigraphy, and fatigue by the Karolinska Sleepiness Scale (KSS) over 14 consecutive days. The KSS ratings given at top of descent (TOD) served as the main outcome.RESULTS: The probability of high fatigue (KSS ≥ 7) at TOD was 0.41 and 0.32 during long (>10 h) and short night (≤10 h) FDPs, respectively. The corresponding value was 0.19 for early starts, 0.31 for late finishes, 0.34 for night FDPs, and 0.15 for day FDPs (reference). The main predictors of high fatigue were FDP’s encroachment on the window of circadian low (WOCL, 02:00 h–05:59 h) and prior sleep. Within the night category, FDPs fully covering the WOCL showed the highest probability of high fatigue at TOD (0.42).DISCUSSION: Late finish and night FDPs warrant special attention in fatigue management. Within the night category, the same holds for FDPs that fully cover the WOCL. To manage fatigue, adjustments of the FTLs seem to be a limited strategy and therefore other measures, including maximizing preflight sleep, are needed.Sallinen M, van Dijk H, Aeschbach D, Maij A, Åkerstedt T. A large-scale European Union study of aircrew fatigue during long night and disruptive duties. Aerosp Med Hum Perform. 2020; 91(8):628–635.

INTRODUCTION: Many regulations for aeromedical assessments state that a ratio between forced expiratory volume in one second (FEV₁) and forced vital capacity (FVC) of < 0.7 should be evaluated by a pulmonary specialist. The Global Lung Initiative (GLI) reference values introduced the lower limit of normal (LLN 2.5), in which the lowest 2.5% of the population is regarded as abnormal, instead of a fixed ratio. This study assesses the impact of adopting GLI reference values on aeromedical evaluation and referrals.METHODS: The Royal Netherlands Air Force performed 7492 aeromedical assessments between February 2012 and April 2017. Cases with FEV₁/FVC < 0.7 from three groups were selected: 1) men < 25 yr; 2) men > 40 yr; and 3) women, with twice as many matched controls. Pearson's Chi-squared and Fisher’s exact tests were used to analyze the data.RESULTS: From the database, 23 (group 1), 62 (group 2), and 7 (group 3) cases were selected, with 184 controls. Respectively, 17%, 84%, and 29% would not be referred using the GLI. In the controls, this would lead to one additional referral (group 1). Qualitative analysis of the cases who would not be referred using the GLI showed that no significant diagnoses would have been missed.DISCUSSION: Using the GLI LLN 2.5 reference values for pulmonary function tests leads to significantly fewer referrals to a pulmonary specialist without missing relevant pulmonary pathology in our aircrew. This would reduce resources spent on the assessment of aircrew without compromising flight safety.Wingelaar-Jagt YQ, Wingelaar TT, Bülbül M, vd Bergh PP, Frijters E, Staudt E. The effect of using the lower limit of normal 2.5 in pulmonary aeromedical assessments. Aerosp Med Hum Perform. 2020; 91(8):636–640.

BACKGROUND: Caffeine-containing products and dietary supplements are widely used by military populations, but little is known about their use by aviation personnel. This study assessed self-reported sleep, fitness, work-schedules, and caffeine/energy drink use.METHODS: A standardized survey was conducted in person by study personnel using tablet computers. A total of 188 aircrew members from the Combat Aviation Brigade at Fort Campbell, KY, participated in the survey. Focus groups were conducted with a subset of 47 subjects.RESULTS: The majority of subjects reported their physical fitness, health, and diets were good. They reported sleeping about 6 h per day and stated they needed additional sleep to feel fully rested. Their caffeine consumption averaged 346 ± 23 mg · d⁻¹ with most derived from coffee (139 ± 12 mg · d⁻¹) and energy drinks (110 ± 13 mg · d⁻¹). About half (55%) of participants used energy drinks at least once per week and they consumed greater amounts of caffeine than nonusers. Focus group data indicated crewmembers primarily consumed energy drinks to enhance performance degraded by variations in work schedules and lack of sufficient sleep. Participants expressed a desire for additional education on diets and energy drinks as well as on aeromedical policies governing energy drink and supplement use.CONCLUSIONS: Caffeinated products, including coffee and energy drinks, are routinely used by Army aircrews to increase alertness. Aircrew personnel consider them generally safe, but would like to receive education about these beverages, other dietary issues, and Army policies governing their use in aircrew.Bukhari AS, Caldwell JA, DiChiara AJ, Merrill EP, Wright AO, Cole RE, Hatch-McChesney A, McGraw SM, Lieberman HR. Caffeine, energy beverage consumption, fitness, and sleep in U.S. Army aviation personnel. Aerosp Med Hum Perform. 2020; 91(8):641–650.

INTRODUCTION: Although the impact of microorganisms on their hosts has been investigated for decades, recent technological advances have permitted high-throughput studies of the collective microbial genomes colonizing a host or habitat, also known as the microbiome. This literature review presents an overview of microbiome research, with an emphasis on topics that have the potential for future applications to aviation safety. In humans, research is beginning to suggest relationships of the microbiome with physical disorders, including type 1 and type 2 diabetes mellitus, cardiovascular disease, and respiratory disease. The microbiome also has been associated with psychological health, including depression, anxiety, and the social complications that arise in autism spectrum disorders. Pharmaceuticals can alter microbiome diversity, and may lead to unintended consequences both short and long-term. As research strengthens understanding of the connections between the microbiota and human health, several potential applications for aerospace medicine and aviation safety emerge. For example, information derived from tests of the microbiota has potential future relevance for medical certification of pilots, accident investigation, and evaluation of fitness for duty in aerospace operations. Moreover, air travel may impact the microbiome of passengers and crew, including potential impacts on the spread of disease nationally and internationally. Construction, maintenance, and cleaning regimens that consider the potential for microbial colonization in airports and cabin environments may promote the health of travelers. Altogether, the mounting knowledge of microbiome effects on health presents several opportunities for future research into how and whether microbiome-based insights could be used to improve aviation safety.Davis JT, Uyhelji HA. Aviation and the microbiome. Aerosp Med Hum Perform. 2020; 91(8):651–661.

INTRODUCTION: Healthy individuals may present with acute pulmonary edema when exposed to extreme environments (high-altitude or deep diving) or while performing strenuous exercises. Recent data support the hypothesis that these forms of acute pulmonary edema might be due to a limited number of stimuli, often overlapping each other, inducing pulmonary capillary stress failure.DISCUSSION: Pathophysiology of nontoxic pulmonary edema occurring in healthy people is still incompletely understood, but recent data suggest a role of three factors (hypoxia, increase in ambient pressure, and physical exercise) that, alone or in combination, may increase pulmonary capillary pressure up to a level overcoming the mechanical resistance of the blood-gas barrier. Evidence has been recently provided to support the existence of a genetic pattern predisposing healthy subjects to pulmonary edema. This paper reviews the evidence supporting a common background for pulmonary edema triggered by extreme environments or heavy effort; a preventive and therapeutic strategy will also be proposed. From these data, hypotheses on the pathophysiology of other forms of noncardiac related pulmonary edema, as those associated with obstructive sleep-apnea syndrome or during post-surgery intensive care, will be proposed.Marabotti C, Cialoni D, Pingitore A. Acute pulmonary edema in healthy subjects. Aerosp Med Hum Perform. 2020; 91(8):662–668.

INTRODUCTION: Aerial ports are being modernized with automated technologies, but the impact on musculoskeletal injury (MSKI) is unknown.METHODS: In this retrospective cohort study of U.S. Air Force aerial port technicians and traffic management technicians, we compared reported injury rates from January 2006–December 2016 and Veterans Benefits Administration disability compensation claims awarded from January 2001–March 2017. Ton-adjusted injury rates, associated lost/affected duty time, and percent risk attributable to lack of automation were compared at Dover Air Force Base (which features base-specific automation), Travis Air Force Base, Ramstein Air Base, and Yokota Air Base.RESULTS: Injuries most often occurred during aircraft/flight line activities and were typically sprains/strains, with extremities being most affected. Among aerial port technicians there were 8.0 injury reports per 1000 person-years compared to 5.2 per 1000 among traffic management technicians (incidence rate ratio = 1.5; 95% CI: 0.9, 3.0). Of the aerial port technicians with a compensation award, 70.7% included an MSKI component, whereas 75.7% of traffic management awards included an MSKI component. Aerial port technicians at Dover AFB experienced 1.4 injury reports per 1000 personnel per 1000 cargo-tons per year, lower than the other ports: 3.2 (Travis); 3.7 (Ramstein); and 7.6 (Yokota). Overall, 56% of injuries at Travis, 62% at Ramstein, and 82% at Yokota could be attributed to absence of Dover-like automation. However, mean lost/affected duty days at Dover (12.4) far exceeded those at the other bases (range: 4.5–8.6).DISCUSSION: Automating aerial ports may reduce injury rates, but the impact on lost/affected duty time requires further investigation.Bylsma VFH, Webber BJ, Erich RA, Voss JD. Musculoskeletal injuries and automation in aerial port operations. Aerosp Med Hum Perform. 2020; 91(8):669–673.

BACKGROUND: Ejection injuries involving the eyes have become uncommon due to effective protection by helmets and visors. We report a unique case of intraocular lead foreign body injury occurring after ejection from a Hawk aircraft in a pilot who had his helmet and visor on.CASE REPORT: A 40-yr-old male pilot sustained facial injuries after ejection from a Hawk aircraft. He had multiple foreign bodies embedded in the skin around his jaw, corneal foreign bodies, and self-sealed corneal and lens entry in left eye, with one foreign body lodged within the lens and two in the vitreous behind the lens. The foreign bodies showed low reflectivity on CT scan suggestive of plastic. However, spectroscopic and electron microscopic analysis of pieces removed from the cornea confirmed the material to be predominantly lead, which came from the miniature detonator cord (MDC). An electroretinogram (ERG) showed reduction of scotopic b wave amplitude in the affected eye. The pilot underwent intravitreal foreign body removal successfully through pars plana vitrectomy. Post-removal vision recovered from 20/60 to 20/20 with ERG also showing recovery of scotopic b wave amplitude from 100 μV to 180 μV.DISCUSSION: Though systemic toxicity due to high blood levels of lead are well known, this case is unique in demonstrating direct retinal toxicity because of intravitreal lead foreign body. It also raises aeromedical concerns about the hazards of MDC splatter despite full protection with helmet and visor.Khan MA, Gaur D, Murthy PC, Pandey A. Lead intraocular foreign body injury following ejection. Aerosp Med Hum Perform. 2020; 91(8):673–677.

BACKGROUND: Facial baroparesis is reversible palsy of the facial nerve that may occur due to a pressure change in the middle ear when ascending in an airplane or during scuba diving. The objective is to present a rare case of facial paresis during airplane travel.CASE REPORT: We report a 49-yr-old female patient who presented with a 30-min episode of transient right facial paresis with loss of taste during airplane travel. Brain magnetic resonance imaging (MRI) showed a small left parietal developmental venous anomaly, extensive inflammation of the paranasal sinuses, which were almost completely obstructed with thickened mucosa and mastoid cell secretion bilaterally. Nasal decongestants and antibiotics were prescribed. No new neurological signs or symptoms were noticed.DISCUSSION: Reversible facial baroparesis due to the pressure change in the middle ear should be considered in cases where present medical history includes ascent/airplane takeoff or prolonged diving and should not be mistaken for transitory ischemic attack.Mikuš K, Tudor KI, Pavliša G, Petravić D. Reversible peripheral facial nerve palsy during airplane travel. Aerosp Med Hum Perform. 2020; 91(8):679–681.