INTRODUCTION: The effects of repeated centrifugation in association with head-down tilt (HDT) bed rest (BR) on the mediation of basic reflexes associated with the major postural muscles was investigated as a potential countermeasure for maintaining balance control and neuromotor reflex function.METHODS: There were 15 male volunteers who were exposed to 21 d of 6° HDT-BR. Eight were treated with daily 1-h artificial gravity (AG) exposures aboard a short radius centrifuge that provided 1-g footward loading at heart level. The other seven served as HDT-BR control subjects. Balance control was assessed using a standard computerized dynamic posturography (CDP) protocol that was modified by adding low-frequency pitch-plane head movements. Neuromotor reflex function was assessed using tendon stretch reflexes (MSR) and functional stretch reflex (FSR) data collected from the triceps surae muscle group.RESULTS: CDP performance was degraded by HDT-BR in both groups (ranging from 24 to 26%), but was unaffected by AG. BR also degraded MSR and FSR functions in both groups, with increased peak reflex latencies between 1.5 and 1.95 ms, but AG maintained pre-BR latencies for the MSR subjects.DISCUSSION: AG exposure did not modify balance control from pre-BR responses, but did help prevent decrements in FSR latencies post-BR.Paloski WH, Reschke MF, Feiveson AH. Bed rest and intermittent centrifugation effects on human balance and neuromotor reflexes. Aerosp Med Hum Perform. 2017; 88(9):812–818.

BACKGROUND: Mild hypercapnia combined with a cephalad fluid shift [e.g., that occurring during spaceflight or laparoscopic surgery with head-down tilt (HDT)] might affect cerebral autoregulation. However, no reports have described the effects of the combination on dynamic cerebral autoregulation. Therefore, we tested the hypothesis that the combination of mild hypercapnia and a cephalad fluid shift would attenuate dynamic cerebral autoregulation.METHODS: There were 15 healthy male volunteers who were exposed to 4 10-min protocols in which they received air in the supine position (Placebo/Supine), 3% carbon dioxide (CO₂) in the supine position (CO₂/Supine), air with −10° HDT (Placebo/HDT) and 3% CO₂ with −10° HDT (CO₂/HDT). Dynamic cerebral autoregulation was evaluated using a transfer function analysis of the beat-to-beat variability in mean arterial blood pressure (ABP) and mean cerebral blood flow (CBF) velocity.RESULTS: The phase in the low-frequency range was significantly lower during CO₂/HDT than all other protocols, where CO₂/HDT was −25% lower than Placebo/Supine (CO₂/HDT, 0.49 ± 0.21; Placebo/Supine, 0.65 ± 0.16 radians). The transfer function gain in the low-frequency range was significantly higher during CO₂/HDT than all other protocols, where CO₂/HDT was 26% higher than Placebo/Supine (CO₂/HDT, 1.08 ± 0.34; Placebo/Supine, 0.86 ± 0.28 cm · s⁻¹ · mmHg⁻¹). However, neither the CO₂/Supine nor Placebo/HDT showed significant differences compared with the Placebo/Supine.DISCUSSION: Even short-term exposure to 3% CO₂ plus HDT increased synchrony and the magnitude of transmission between ABP and CBF in the low-frequency range. Thus, the combination of mild hypercapnia and a cephalad fluid shift attenuated dynamic cerebral autoregulation.Kurazumi T, Ogawa Y, Yanagida R, Morisaki H, Iwasaki K. Dynamic cerebral autoregulation during the combination of mild hypercapnia and cephalad fluid shift. Aerosp Med Hum Perform. 2017; 88(9):819–826.

BACKGROUND: Intermittent artificial gravity (AG) training over days and weeks has been shown to improve the human orthostatic tolerance limit (OTL) and improve cardiovascular regulation in response to orthostatic stress. Effects of a single AG exposure are currently unknown.METHODS: We tested cardiovascular responses to orthostatic stress in 16 hypovolemic subjects (9 men and 7 women), once following a single, short (∼90 min) bout of AG and once following a similar period of head-down bed rest (HDBR). Hypovolemia was produced by intravenous furosemide infusion (20 mg) and orthostatic stress was produced by combined 70° head-up tilt (HUT) and progressively increasing lower body negative pressure until symptoms of presyncope developed. To assess reflex-induced changes in cardiovascular regulation, heart rate and blood pressure variability were analyzed by spectral analysis and baroreflex activity was evaluated by transfer function analysis.RESULTS: Compared to HDBR, a short AG exposure increased men’s low frequency (0.04–0.15 Hz) power of systolic blood pressure (SBP_LF), but did not change women’s SBP_LF responses to orthostatic stress. In response to 70° HUT, compared to supine, low frequency phase delay (Phase_LF) between systolic blood pressure and RR intervals increased by ∼20% following HDBR, but did not change following AG, reflecting improved baroreflex activity at a milder level of orthostatic stress after AG.CONCLUSIONS: These results indicate that a short bout of AG increased both sympathetic and baroreflex responsiveness to orthostatic stress in hypovolemia-induced, cardiovascular-deconditioned men and women, which may contribute to the AG-induced improvement of OTL shown in our previous reports.Zhang Q, Evans JM, Stenger MB, Moore FB, Knapp CF. Autonomic cardiovascular responses to orthostatic stress after a short artificial gravity exposure. Aerosp Med Hum Perform. 2017; 88(9):827–833.

BACKGROUND: The objective assessment of psychophysiological arousal during challenging flight maneuvers is of great interest to aerospace medicine, but remains a challenging task. In the study presented here, a vector-methodological approach was used which integrates different psychophysiological variables, yielding an integral arousal index called the Psychophysiological Arousal Value (PAV).METHODS: The arousal levels of 15 male pilots were assessed during predetermined, well-defined flight maneuvers performed under simulated and real flight conditions.RESULTS: The physiological data, as expected, revealed inter- and intra-individual differences for the various measurement conditions. As indicated by the PAV, air-to-air refueling (AAR) turned out to be the most challenging task. In general, arousal levels were comparable between simulator and real flight conditions. However, a distinct difference was observed when the pilots were divided by instructors into two groups based on their proficiency in AAR with AWACS (AAR-Novices vs. AAR-Professionals). AAR-Novices had on average more than 2000 flight hours on other aircrafts. They showed higher arousal reactions to AAR in real flight (contact: PAV score 8.4 ± 0.37) than under simulator conditions (7.1 ± 0.30), whereas AAR-Professionals did not (8.5 ± 0.46 vs. 8.8 ± 0.80).DISCUSSION: The psychophysiological arousal value assessment was tested in field measurements, yielding quantifiable arousal differences between proficiency groups of pilots during simulated and real flight conditions. The method used in this study allows an evaluation of the psychophysiological cost during a certain flying performance and thus is possibly a valuable tool for objectively evaluating the actual skill status of pilots.Johannes B, Rothe S, Gens A, Westphal S, Birkenfeld K, Mulder E, Rittweger J, Ledderhos C. Psychophysiological assessment in pilots performing challenging simulated and real flight maneuvers. Aerosp Med Hum Perform. 2017; 88(9):834–840.

INTRODUCTION: Creation of the cosmonaut in-flight physical training process is currently based on the leading role of support afferents in the development of hypogravity changes in the motor system. We assume that the strength of support afferents is related to the magnitude of the ground reaction forces (GRF). For this purpose it was necessary to compare the GRF magnitude on the Russian BD-2 treadmill for different locomotion types (walking and running), modes (active and passive), and subjects.METHODS: Relative GRF values were analyzed while subjects performed walking and running during active and passive modes of treadmill belt movement under 1 G (N = 6) and 0 G (N = 4) conditions.RESULTS: For different BD-2 modes and both types of locomotion, maximum GRF values varied in both 0 G and 1 G. Considerable individual variations were also found in the locomotion strategies, as well as in maximum GRF values. In 0 G, the smallest GRF values were observed for walking in active mode, and the largest during running in passive mode. In 1 G, GRF values were higher during running than while walking, but the difference between active and passive modes was not observed; we assume this was due to the uniqueness of the GRF profile.DISCUSSION: The maximum GRF recorded during walking and running in active and passive modes depended on the individual pattern of locomotion. The maximum GRF values that we recorded on BD-2 were close to values found by other researchers. The observations from this study could guide individualized countermeasures prescriptions for microgravity.Fomina E, Savinkina A. Locomotion strategy and magnitude of ground reaction forces during treadmill training on ISS. Aerosp Med Hum Perform. 2017; 88(9):841–849.

INTRODUCTION: Paratrooper training courses are very demanding, leading to a high number of drop-outs, despite existing selection criteria. This study investigated physiological, neuropsychological, and subjective data of completers and drop-outs during paratrooper training to identify potential predictive indices.METHODS: Tested were 24 paratrooper soldiers before (t₀), after 8 wk (t₁), and at the end of a 12-wk training camp (t₂). There were 11 soldiers who completed the course and 13 dropped out. The Training OPtimalisation test (TOPtest) uses two maximum exercise events to assess changes in measured parameters. The TOPtest was administered at t₀, t₁, and t₂; physiological [i.e., adrenocorticotrophic hormone (ACTH), cortisol, heart rate (HR)], neuropsychological (Stroop, Flanker, Go NoGo, Task Switch), and subjective data [Profile of Mood States (POMS)] were collected. Physiological and subjective raw data was gathered pre- and post-test from each of the two maximum exercise tests. The pre/post-test change of each parameter’s raw values was calculated as the parameter’s reactivity (or delta score).RESULTS: At t₀, drop-outs showed a significantly smaller HR reactivity (117.9 ± 14.0 vs.107.7 ± 10.6). Delta scores of tension and fatigue values differed significantly between completers and drop-outs at t₀. Completers’ physiological reactivity during the TOPtest at t₂ (HR: 105.91 ± 13.68 vs. 95.55 ± 10.28) was significantly reduced and became comparable to the drop-outs’ reactivity at t₀. Delta scores of fatigue and tension values showed a similar pattern.DISCUSSION: Reactivity of HR, tension, and fatigue parameter values were found to have predictive value in identifying completers vs. drop-outs of an elite paratrooper training course.Vrijkotte S, Meeusen R, Roelands B, Kubesch S, Mairesse O, de Schutter G, Pattyn N. Refining selection for elite troops by predicting military training outcome. Aerosp Med Hum Perform. 2017; 88(9):850–857.

INTRODUCTION: Pilots’ mental health is an issue of crucial importance that may endanger flight safety. As such, it is of profound significance to address the question of what characteristics are protective of mental health among pilots. The present study aimed to explore the indirect effects of emotional intelligence (EI) on depression and anxiety via proactive coping, and examine the moderating role of previous flight experience (PFE) in the conditional indirect effect of EI on depression through proactive coping.METHODS: A cross-sectional regression design was used to measure EI (Trait Meta Mood Scale), proactive coping (Proactive Coping Scale), depression (The PHQ-9), and anxiety (The GAD-7) among 319 Chinese civil pilots from China Southern Airlines. Mediation and moderated mediation effects were explored using regression analyses and were confirmed by the bootstrapping approach.RESULTS: Pilots reported relatively low levels of depression (M = 0.39, SD = 0.24) and anxiety (M = 0.22, SD = 0.23). Married pilots had higher levels of depression (t = 2.46) and anxiety (t = 3.07) than single pilots. Proactive coping mediated the association between EI and depression (B = −0.25), as well as the relationship between EI and anxiety (B = −0.23). Moreover, conditional process analysis showed that PFE moderated the indirect effect of EI on depression through proactive coping (b₃ = 0.005), in which simple slope analysis showed a stronger mediating effect for pilots with more PFE (simple slope = −0.14).DISCUSSION: The results showed that EI and proactive coping had protective potential in the prevention of depression and anxiety. Implications for the promotion of mental health and diminishing depression and anxiety among pilots are discussed.Guo Y, Ji M, You X, Huang J. Protective effects of emotional intelligence and proactive coping on civil pilots’ mental health. Aerosp Med Hum Perform. 2017; 88(9):858–865.

INTRODUCTION: In the Republic of Korea Air Force, the health of pilots is strictly supervised, but there is comparatively not enough interest in aircraft mechanics’ health. Among mechanics, who are heavily involved in military aircraft maintenance, the occurrence of sudden cardio-cerebrovascular diseases (CCVDs) is a possible risk factor during the maintenance process, which should be performed perfectly.METHODS: We performed health examinations on 2123 male aircraft pilots and 1271 aircraft mechanics over 30 yr of age and determined the prevalence of metabolic syndrome (MetS), an important risk factor for CCVDs.RESULTS: The prevalence of MetS in the aircraft mechanics (21.3%) was significantly higher than in the pilots (12.6%), and the gap in prevalence tended to grow as age increased. Among aircraft mechanics in their 30s and 40s, the prevalence of MetS was lower than in the general population. However, the prevalence of MetS among aircraft mechanics in their 50s (36.0%) was similar to that in the general population (35.7%).CONCLUSIONS: Systematic health management is needed for aircraft mechanics for aviation safety and for the maintenance of military strength via the prevention of CCVDs.Kim M-B, Kim H-J, Kim S-H, Lee S-H, Lee S-H, Park W-J. Metabolic syndrome and cardio-cerebrovascular risk disparities between pilots and aircraft mechanics. Aerosp Med Hum Perform. 2017; 88(9):866–870.

BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder with symptoms of inattention and/or hyperactivity-impulsivity that interfere with functioning and/or development. ADHD occurs in about 2.5% of adults. ADHD can be an excluding medical condition among pilots due to the risk of attentional degradation and therefore impact on flight safety. Diagnosis of ADHD is complex, which complicates aeromedical assessment. This study highlights fatal accident cases among pilots with ADHD and discusses protocols to detect its presence to help to assess its importance to flight safety.METHODS: To identify fatal accidents in aviation (including airplanes, helicopters, balloons, and gliders) in the United States between the years 2000 to 2015, the National Transportation Safety Board (NTSB) database was searched with the terms ADHD, attention deficit hyperactivity disorder, and attention deficit disorder (ADD).RESULTS: The NTSB database search for fatal aviation accidents possibly associated with ADHD yielded four accident cases of interest in the United States [4/4894 (0.08%)]. Two of the pilots had ADHD diagnosed by a doctor, one was reported by a family member, and one by a flight instructor. An additional five cases were identified searching for ADD [5/4894 (0.1%)]. Altogether, combined ADHD and ADD cases yielded nine accident cases of interest (0.18%).DISCUSSION: It is generally accepted by aviation regulatory authorities that ADHD is a disqualifying neurological condition. Yet FAA and CASA provide specific protocols for tailor-made pilot assessment. Accurate evaluation of ADHD is essential because of its potential negative impact on aviation safety.Laukkala T, Bor R, Budowle B, Sajantila A, Navathe P, Sainio M, Vuorio A. Attention-deficit/hyperactivity disorder and fatal accidents in aviation medicine. Aerosp Med Hum Perform. 2017; 88(9):871–875.

BACKGROUND: Airline carriers have equipment, procedures, and protocols in place to handle in-flight medical events (IFMEs). Community physicians may be asked for aid during IFMEs. Cross-Sectional Survey of Physicians on Providing Volunteer Care for In-Flight Medical Events surveyed self-assessed awareness and knowledge, perceived barriers, and suggestions for improving responses to IFMEs.METHODS: We composed a survey regarding clinicians’ self-assessed understanding of in-flight resources, procedures, flight environmental issues, and Good Samaritan protections. The survey was distributed primarily via electronic mail to medical staff list serves to a total of approximately 1300 physicians representing 2 health networks that serve urban, suburban, and rural areas in both inpatient and outpatient settings.RESULTS: Total number of responses was 418. Physician response rate was 29.2% (379/1300). In 3% (39/1300), the responder either failed to indicate their background or was another type of health care professional (e.g., dentist, medical student, physician assistant). Of the physicians, 37.5% (142/379) were primary care and 42% (177/418) of responders reported at least one experience of being asked to volunteer. When asked how well they understand the protocols with which medical events are handled, 64% (262/412) responded “not at all” and 23% (94/412) reported “a little” knowledge. Only 56% (223/397) answered that 75% or more of U.S. flights have ground medical support available. There were 73% (298/411) who believed airlines were required to have medical supplies, but 54% (222/410) reported no knowledge of supplies available. A total of 69% (279/403) believed or were sure that the U.S. has a Good Samaritan law that applies to IFMEs.DISCUSSION: Many physicians lack basic knowledge about IFMEs. Responders may assist more effectively if better informed about protocols and the availability of ground medical support. Education and timely information support are recommended.Chatfield E, Bond WF, McCay B, Thibeault C, Alves PM, Squillante M, Timpe J, Cook CJ, Bertino RE. Cross-Sectional Survey of Physicians on Providing Volunteer Care for In-Flight Medical Events. Aerosp Med Hum Perform. 2017; 88(9):876–879.

BACKGROUND: Cerebellar infarction is an uncommon but serious cause of isolated acute vestibular symptoms, particularly in young, healthy individuals, and can easily be overlooked. We present two cases of cerebellar infarction in U.S. Air Force pilots, one of which occurred during flight.CASE REPORTS: A 41-yr-old man developed acute vertigo, disequilibrium, nausea, and headache, with progressive slow symptomatic improvement, and presented to medical attention 4 d after symptom onset. Brain magnetic resonance imaging showed right inferomedial cerebellar infarction. Echocardiography discovered patent foramen ovale and atrial septal aneurysm. A 40-yr-old man developed severe vertigo, nausea, and vomiting during initial aircraft descent. Head computed tomography scan was performed acutely and was normal. Initial assessment was benign paroxysmal positional vertigo. Brain magnetic resonance imaging 1 mo after symptom onset showed a small right inferior cerebellar infarction. Patent foramen ovale and bilateral atrial enlargement were seen on echocardiography. Both pilots made full neurological recoveries and were eventually returned to flight status.DISCUSSION: Central causes of isolated acute vestibular symptoms are uncommon and are often not considered in otherwise healthy individuals. Cerebellar infarction is one of these uncommon but increasingly recognized causes of acute vestibular symptoms. As evaluation and management of central causes are much different from peripheral conditions, prompt localization confirmation is paramount. Accurate evidence-based bedside screening methods are available for rapid localization. Awareness of the possibility of central etiologies and careful clinical evaluation with application of bedside screening methods in patients with acute vestibular symptoms will reduce the number of inaccurate diagnoses.Hesselbrock RR. Cerebellar infarction presenting with acute vestibular syndrome in two U.S. Air Force pilots. Aerosp Med Hum Perform. 2017; 88(9):880–883.

Casstevens EA. You’re the flight surgeon: an unexpected twist. Aerosp Med Hum Perform. 2017; 88(9):884–887.

Hatcher DR. You’re the flight surgeon: migraine aura without headaches. Aerosp Med Hum Perform. 2017; 88(9):887–891.