INTRODUCTION: Military aeromedical evacuation, especially that associated with the present Middle East conflict, is seeing increasing research. This ecological study initiates research into the validating flight surgeon by looking at cabin altitude restriction (CAR), arguably the validating flight surgeon’s prescription with the highest patient-mission impact, and its association with postflight complications.METHODS: CAR rates from January 2006 through February 2008 were determined from the U.S. Transportation Command Regulating and Command and Control Evacuation System database. Postflight complication rates—the rate of patients with postflight complications (PFC) and the postflight complications per 100 patients (PFC-100)—from January 2007 through June 2008 were calculated from the Landstuhl Regional Medical Center trauma database. CAR and complication rates were examined before, during, and after the authors’ deployment. In addition, the relationship between CAR and postflight complication rates was investigated; as the rates were nonlinear, a Spearman correlation was performed.RESULTS: CAR rates during the authors’ deployments were significantly up compared to the authors’ predecessors or successors; their predecessors and successors did not differ statistically. Likewise, the PFC rate during the authors’ deployments was significantly lower than that of the before or after time frames. Furthermore, a statistically significant inverse relationship between CAR and PFC rates (Spearman rho = −0.587) as well as CAR and PFC-100 rates (Spearman rho = −0.568) was demonstrated.DISCUSSION: CAR rate was inversely correlated to PFC and PFC-100 rates. This finding suggests that aggressive prescribing of CARs may have a salutary effect on postflight complication rates and bears further investigation.Butler WP, Steinkraus LW, Burlingame EE, Fouts BL, Serres JL. Complication rates in altitude restricted patients following aeromedical evacuation. Aerosp Med Hum Perform. 2016; 87(4):352–359.
BACKGROUND: Motion sickness can influence energy homeostasis by enhancing thermolysis. This study tested the hypothesis that resting energy expenditure (REE), as the major component of thermogenesis, might also play a role during motion sickness.METHODS: The effect of seasickness on REE at sea was examined in 71 healthy Chinese male volunteers. Change in REE, heart rate variability (HRV), blood ghrelin levels, and leptin levels were observed across baseline, voyage, and recovery stages. Seasickness severity was assessed using the Graybiel motion sickness questionnaire (GMSQ), and the nausea syndrome rating (NSR) of each participant was also evaluated. REE was examined by indirect calorimetry. HRV was derived from the electrocardiogram to analyze cardiac sympathovagal activity. Blood ghrelin and leptin levels were tested by radioimmunoassay.RESULTS: In subjects with severe seasickness during the voyage, the GMSQ and NSR scores were higher than in subjects with slight and moderate seasickness. The REE declined significantly compared to baseline and recovery levels and was lower than in subjects with slight and moderate seasickness. Cardiac sympathetic activity was significantly decreased, while vagal activity was increased. Plasma ghrelin levels were also significantly increased and were negatively correlated with the measured REE levels and positively correlated with NSR as well as change of HRV LF/HF ratio from baseline.DISCUSSION: Severe motion sickness induces REE suppression, which may be attributed to dramatic alteration of sympathovagal activity and plasma ghrelin levels in humans.Wang J-Q, Qi R-R, Pan L-L, Zhou W, Zhang L-L, Cai Y-L. Motion sickness and resting energy expenditure in Chinese male adults. Aerosp Med Hum Perform. 2016; 87(4):360–366.
BACKGROUND: This study aimed to investigate the feasibility of determining the physiological parameters associated with the ability to complete simulated exploration type tasks at metabolic rates which might be expected for lunar and Martian ambulation.METHODS: Running Vo2max and gas exchange threshold (GET) were measured in 21 volunteers. Two simulated extravehicular activity field tests were completed in 1 G in regular athletic apparel at two intensities designed to elicit metabolic rates of ∼20.0 and ∼30.0 ml · kg−1 · min−1, which are similar to those previously reported for ambulation in simulated lunar- and Martian-based environments, respectively.RESULTS: All subjects were able to complete the field test at the lunar intensity, but 28% were unable to complete the field test at the Martian intensity (non-Finishers). During the Martian field test there were no differences in Vo2 between Finishers and non-Finishers, but the non-Finishers achieved a greater %Vo2max compared to Finishers (78.4 ± 4.6% vs. 64.9 ± 9.6%). Logistic regression analysis revealed fitness thresholds for a predicted probability of 0.5, at which Finishing and non-Finishing are equally likely, and 0.75, at which an individual has a 75% chance of Finishing, to be a Vo2max of 38.4 ml · kg−1 · min−1 and 40.0 ml · kg−1 · min−1 or a GET of 20.1 ml · kg−1 · min−1 and 25.1 ml · kg−1 · min−1, respectively (χ2 = 10.2). Logistic regression analysis also revealed that the expected %Vo2max required to complete a field test could be used to successfully predict performance (χ2 = 19.3).DISCUSSION: The results of the present investigation highlight the potential utility of Vo2max, particularly as it relates to the metabolic demands of a surface ambulation, in defining successful completion of planetary-based exploration field tests.Ade CJ, Broxterman RM, Craig JC, Schlup SJ, Wilcox SL, Warren S, Kuehl P, Gude D, Jia C, Barstow TJ. Prediction of lunar- and Martian-based intra- and site-to-site task performance. Aerosp Med Hum Perform. 2016; 87(4):367–374.
INTRODUCTION: This study investigated pilots’ ability by examining the effects of flight experience and task demand on physiological reactions, and analyzing the diagnostic meanings underlying correlated parameters.METHOD: A total of 12 experienced pilots and 12 less experienced pilots performed 4 simulated flight tasks, including normal and emergency situations. Fixation duration (FD), saccade rate (SR), blink rate (BR), heart rate (HR), respiration rate (RR), and respiration amplitude (RA) were measured during the tasks.RESULTS: More experienced pilots adapted their SR flexibly to changing task demands and had significantly lower SR than less experienced pilots during emergency tasks (29.6 ± 20.0 vs. 70.1 ± 67.1 saccades/min). BR, HR, and RR were affected by pilot experience but not by task demand. More experienced pilots had lower BR, HR, and RR than less experienced pilots during both normal tasks (BR: 14.3 ± 13.0 vs. 32.9 ± 25.8 blinks/min; HR: 72.7 ± 7.9 vs. 83.2 ± 7.2 bpm; RR: 15.4 ± 2.1 vs. 19.5 ± 5.2 breaths/min) and emergency tasks (BR: 10.2 ± 5.0 vs. 32.3 ± 20.8 blinks/min; HR: 73.3 ± 7.3 vs. 82.2 ± 11.6 bpm; RR: 15.6 ± 1.9 vs. 18.0 ± 3.2 breaths/min). FD and RA were not sensitive to either flight experience or task demand.CONCLUSIONS: Physiological reactions have the potential to reflect pilots’ ability from different aspects. SR and BR could indicate pilots’ differences in information access strategy. HR and RR could reflect a pilot’s physical fitness. These findings are useful for understanding a pilot’s ability.Wang Z, Zheng L, Lu Y, Fu S. Physiological indices of pilots’ abilities under varying task demands. Aerosp Med Hum Perform. 2016; 87(4):375–381.
BACKGROUND: Current color vision (CV) tests used for aviation screening in the U.S. Army only provide pass-fail results, and previous studies have shown variable sensitivity and specificity. The purpose of this study was to evaluate seven CV tests to determine an optimal CV test screener that potentially could be implemented by the U.S. Army.METHODS: There were 133 subjects [65 Color Vision Deficits (CVD), 68 Color Vision Normal (CVN)] who performed all of the tests in one setting. CVD and CVN determination was initially assessed with the Oculus anomaloscope. Each test was administered monocularly and according to the test protocol. The main outcome measures were test sensitivity, specificity, and administration time (automated tests).RESULTS: Three of the four Pseudoisochromatic Plate (PIP) tests had a sensitivity/specificity > 0.90 OD/OS, whereas the FALANT tests had a sensitivity/specificity > 0.80 OD/OS. The Cone Contrast Test (CCT) demonstrated sensitivity/specificity > 0.90 OD/OS, whereas the Color Assessment and Diagnosis (CAD) test demonstrated sensitivity/specificity > 0.85 OD/OS. Comparison with the anomaloscope (“gold standard”) revealed no significant difference of sensitivity and specificity OD/OS with the CCT, Dvorine PIP, and PIPC tests. Finally, the CCT administration time was significantly faster than the CAD test.DISCUSSION: The current U.S. Army CV screening tests demonstrated good sensitivity and specificity, as did the automated tests. In addition, some current PIP tests (Dvorine, PIPC), and the CCT performed no worse statistically than the anomaloscope with regard to sensitivity/specificity. The CCT letter presentation is randomized and results would not be confounded by potential memorization, or fading, of book plates.Walsh DV, Robinson J, Jurek GM, Capó-Aponte JE, Riggs DW, Temme LA. A performance comparison of color vision tests for military screening. Aerosp Med Hum Perform. 2016; 87(4):382–387.
BACKGROUND: This is a systematic review of suicide and homicide-suicide events involving aircraft. In aeromedical literature and in the media, these very different events are both described as pilot suicide, but in psychiatry they are considered separate events with distinct risk factors.METHODS: Medical databases, internet search engines, and aviation safety databases were searched in a systematic way to obtain relevant cases. Relevant articles were searched for additional references.RESULTS: There were 65 cases of pilot suicide and 6 cases of passengers who jumped from aircraft found. There were also 18 cases of homicide-suicide found involving 732 deaths. Pilots perpetrated 13 homicide-suicide events. Compared to non-aviation samples, a large percentage of pilot suicides in this study were homicide-suicides (17%).DISCUSSION: Homicide-suicide events occur extremely rarely. However, their impact in terms of the proportion of deaths is significant when compared to deaths from accidents. There is evidence of clustering where pilot suicides occur after by media reports of suicide or homicide-suicide. Five of six homicide-suicide events by pilots of commercial airliners occurred after they were left alone in the cockpit. This, along with a sixth incident in which active intervention by a Japan Air crew saved 147 lives, suggests that having two flight members in the cockpit is potentially protective. No single factor was associated with the risk for suicide or homicide-suicide. Factors associated with both events included legal and financial crises, occupational conflict, mental illness, and relationship stressors. Drugs and/or alcohol played a role in almost half of suicides, but not in homicide-suicides.Kenedi C, Friedman SH, Watson D, Preitner C. Suicide and murder-suicide involving aircraft. Aerosp Med Hum Perform. 2016; 87(4):388–396.
INTRODUCTION: Hyperbaric therapeutic chambers are pressure vessels capable of accommodating one or more persons with the purpose of providing medical treatment. Therapeutic hyperbaric chambers have been in use from the mid-20th century, yet apparently their design has not reached their full potential and they are not compatible with current healthcare facilities design. This paper will present therapeutic hyperbaric chambers from a human-environment-machine perspective in order to highlight their specific problems and requirements, and suggest design concepts that may improve patient satisfaction, quality of treatment, and functionality of the staff. Data were collected from a literature review, a market survey, and personal observations. Main design solutions include personal space and privacy, stress- and anxiety-reducing environments, hazard mitigation, rearrangement of seating, and personalized (user-tailored) entertainment systems. It is suggested that adopting a user-centered design rather than an engineering focus will increase satisfaction and overall 'user experience' of the patients, alleviate psychological issues, and lessen workload and improve functionality of the staff. This study could be applicable and easily adapted to other confined therapeutic environments in which patients are restrained for several hours on a regular basis in receiving treatment, such as dialysis or chemotherapy rooms, and for confined nonmedical situations such as aircrafts and rapid trains.Bitterman N, Bonen A. Design and human factors of therapeutic hyperbaric chambers. Aerosp Med Hum Perform. 2016; 87(4):397–405.
BACKGROUND: Exploration missions to asteroids and Mars will bring new challenges associated with communication delays and more autonomy for crews. Mission safety and success will rely on how well the entire system, from technology to the human elements, is adaptable and resilient to disruptive, novel, or potentially catastrophic events. The recent NASA Extreme Environment Missions Operations (NEEMO) 20 mission highlighted this need and produced valuable “lessons learned” that will inform future research on team adaptation and resilience.METHODS: A team of NASA, industry, and academic members used an iterative process to design a tripod shaped structure, called the CORAL Tower, for two astronauts to assemble underwater with minimal tools. The team also developed assembly procedures, administered training to the crew, and provided support during the mission.RESULTS: During the design, training, and assembly of the Tower, the team learned first-hand how adaptation in extreme environments depends on incremental testing, thorough procedures and contingency plans that predict possible failure scenarios, and effective team adaptation and resiliency for the crew and support personnel.DISCUSSION: Findings from NEEMO 20 provide direction on the design and testing process for future space systems and crews to maximize adaptation. This experience also underscored the need for more research on team adaptation, particularly how input and process factors affect adaption outcomes, the team adaptation iterative process, and new ways to measure the adaptation process.Anglin KM, Kring JP. Lessons from a space analog on adaptation for long-duration exploration missions. Aerosp Med Hum Perform. 2016; 87(4):406–410.
BACKGROUND: Fear of flying (FoF), a common phobia in the developed world, is usually treated with cognitive behavioral therapy, most efficiently when combined with exposure methods, e.g., virtual reality exposure therapy (VRET). We evaluated FoF treatment using VRET in a large motion-based VR system. The treated subjects were seated on a moving platform. The virtual scenery included the interior of an aircraft and a window view to the outside world accompanied by platform movements simulating, e.g., takeoff, landing, and air turbulence. Relevant auditory stimuli were also incorporated.CASE REPORT: Three male patients with FoF underwent a clinical interview followed by three VRETs in the presence and with the guidance of a therapist. Scores on the Flight Anxiety Situation (FAS) and Flight Anxiety Modality (FAM) questionnaires were obtained on the first and fourth visits. Anxiety levels were assessed using the subjective units of distress (SUDs) scale during the exposure. All three subjects expressed satisfaction regarding the procedure and did not skip or avoid any of its stages. Consistent improvement was seen in the SUDs throughout the VRET session and across sessions, while patients’ scores on the FAS and FAM showed inconsistent trends. Two patients participated in actual flights in the months following the treatment, bringing 12 and 16 yr of avoidance to an end.DISCUSSION: This VR-based treatment includes critical elements for exposure of flying experience beyond visual and auditory stimuli. The current case reports suggest VRET sessions may have a meaningful impact on anxiety levels, yet additional research seems warranted.Czerniak E, Caspi A, Litvin M, Amiaz R, Bahat Y, Baransi H, Sharon H, Noy S, Plotnik M. A novel treatment of fear of flying using a large virtual reality system. Aerosp Med Hum Perform. 2016; 87(4):411–416.
Development of a Field-Deployable Psychomotor Vigilance Test to Monitor Helicopter Pilot Performance
INTRODUCTION: Flying a helicopter is a complex psychomotor skill. Fatigue is a serious threat to operational safety, particularly for sustained helicopter operations involving high levels of cognitive information processing and sustained time on task. As part of ongoing research into this issue, the object of this study was to develop a field-deployable helicopter-specific psychomotor vigilance test (PVT) for the purpose of daily performance monitoring of pilots.METHODS: The PVT consists of a laptop computer, a hand-operated joystick, and a set of rudder pedals. Screen-based compensatory tracking task software includes a tracking ball (operated by the joystick) which moves randomly in all directions, and a second tracking ball which moves horizontally (operated by the rudder pedals). The 5-min test requires the pilot to keep both tracking balls centered.RESULTS: This helicopter-specific PVT’s portability and integrated data acquisition and storage system enables daily field monitoring of the performance of individual helicopter pilots. The inclusion of a simultaneous foot-operated tracking task ensures divided attention for helicopter pilots as the movement of both tracking balls requires simultaneous inputs.DISCUSSION: This PVT is quick, economical, easy to use, and specific to the operational flying task. It can be used for performance monitoring purposes, and as a general research tool for investigating the psychomotor demands of helicopter operations. While reliability and validity testing is warranted, data acquired from this test could help further our understanding of the effect of various factors (such as fatigue) on helicopter pilot performance, with the potential of contributing to helicopter operational safety.McMahon TW, Newman DG. Development of a field-deployable psychomotor vigilance test to monitor helicopter pilot performance. Aerosp Med Hum Perform. 2016; 87(4):417–422.
VanValkenburg K. You’re the flight surgeon: a complication of surgical vision correction. Aerosp Med Hum Perform 2016; 87(4):426–429.
DeJulio P. You’re the flight surgeon: malaria prevention in U.S. Air Force aviators. Aerosp Med Hum Perform. 2016; 87(4):429–432.
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