BACKGROUND: Rapid travel over multiple time zones usually results in transient de-synchronization between environmental time and the biological clock of the individual. Common symptoms are increased daytime sleepiness, reduced sleep duration and quality, and performance impairments. Exposure to ocular bright light is known to alleviate jet lag symptoms and facilitate adaptation to a new time zone. Recently, transcranial bright light (TBL) via the ear canals has been shown to have antidepressant, anxiolytic, and psychomotor performance-enhancing effects. In this case we studied whether intermittent TBL exposure can alleviate jet lag symptoms in a randomized, double-blind, placebo-controlled study.METHODS: Intermittent light exposures (4 × 12 min; day 0: 08:00, 10:00, 12:00, 14:00; days 1-6: 10:00, 12:00, 14:00, 16:00) were administered during the 7-d post-travel period after an eastward transatlantic flight. The symptoms of jet lag were measured by the Visual Analog Scale (VAS), the Karolinska Sleepiness Scale (KSS), and the Profile of Mood States (POMS).RESULTS: We found a significant reduction of overall jet lag symptoms (VAS), subjective sleepiness (KSS), and the fatigue, inertia, and forgetfulness subscales of the POMS when comparing the active TBL treatment group (N = 30) to the placebo group (N = 25). For example, the normalized values of VAS in the TBL, but not the placebo, group returned to pre-travel levels by the final post-travel day (6.16 vs. 15.34).DISCUSSION: Results suggest a cumulative effect of TBL, as the effects emerged on post-travel days 3-4. Intermittent TBL seems to alleviate jet lag symptoms.Jurvelin H, Jokelainen J, Takala T. Transcranial bright light and symptoms of jet lag: a randomized, placebo-controlled trial. Aerosp Med Hum Perform. 2015; 86(4):344–350.

BACKGROUND: Hypoxemia secondary to reduced barometric pressure is a complication of ascent to altitude. We designed a study to compare the reversal of hypobaric hypoxemia at 14,000 ft with continuous flow oxygen from a cylinder and pulsed dose oxygen from a portable concentrator.METHODS: There were 30 healthy volunteers who were randomized to one of three study groups, placed in an altitude chamber, and ascended to 14,000 ft. There were 10 subjects in each study group. Subjects breathed room air for 10 min to induce hypoxemia. Oxygen was then delivered via a nasal cannula from a cylinder at 1, 2, or 3 lpm of continuous flow for 10 min. The subjects again breathed room air at altitude for 10 min and were then placed on pulsed dose oxygen and titrated to obtain the continuous flow S_po₂ equivalent. S_po₂, E_tco₂, RR, HR, Hgb, and tissue oxygenation (S_to₂) were continuously recorded.RESULTS: The 1-lpm group's S_po₂ range was 89–99%. The 2-lpm group's S_po₂ range was 95–98%, and the 3-lpm group's S_po₂ range was 95–99%. The 2-lpm and 3-lpm flows were able to correct hypoxemia in every subject. The mean pulsed dose required to achieve an equivalent S_po₂ ranged from 36.8 ml ± 18.9 ml in the 1-lpm arm, and 102.4 ml ± 53.8 in the 3-lpm arm.CONCLUSIONS: Portable oxygen concentrators using pulsed dose technology corrected hypoxemia in every subject. Oxygen concentrators may be an alternative to liquid oxygen or cylinders for use during aeromedical evacuation.Blakeman TC, Rodriquez D Jr, Gerlach TW, Dorlac WC, Johannigman JA, Branson RD. Oxygen requirement to reverse altitude-induced hypoxemia with continuous flow and pulsed dose oxygen. Aerosp Med Hum Perform. 2015; 86(4):351–356.

BACKGROUND: Many in-flight hypoxia-like incidents involve exposure to normobaric hypoxia following an oxygen delivery equipment failure. Studies have documented the effect of hypoxia on specific aspects of human performance. The goal of the present study was to establish the effects of acute hypoxia on cognitive, psychomotor, and perceptual abilities and to chronicle the time required for these capabilities to fully recover to pre-exposure levels.METHODS: Subjects were presented with a battery of tests designed to assess visual acuity, contrast sensitivity, color vision, executive control, and reaction time (simple reaction time, SRT, and choice reaction time, CRT) before, during, immediately following, 60 min, 120 min, and 24 h after hypoxic exposure. Oxygen saturation was continuously measured throughout the duration of the study using near-infrared spectroscopy measured on the forehead and finger pulse oximetry.RESULTS: During the course of six assessment periods, contrast sensitivity, color vision, and subjective workload were affected to varying degrees during hypoxic exposure, but returned to baseline levels soon after a return to normoxia. Conversely, reaction time values and regional cerebral oxygen saturation (M_rSO2), while also affected during hypoxic exposure (MSRT = 362.17 ms, M_CRT = 389.55 ms, M_rSO2 = 79.36%), did not return to baseline levels (M_SRT = 337.35 ms, M_CRT = 372.75 ms, M_rSO2 = 99.75%) until the assessment period 24 h following exposure (M_SRT = 324.35 ms, M_CRT = 366.22 ms, M_rSO2 = 99.10%).DISCUSSION: Evidence from this study suggests an impairment of specific performance characteristics following hypoxic exposure – some for a considerable period of time. Mitigation efforts should focus more on the prevention of hypoxia exposure rather than relying exclusively on training operators to recognize and react earlier to hypoxic symptomology.Phillips JB, Hørning D, Funke ME. Cognitive and perceptual deficits of normobaric hypoxia and the time course to performance recovery. Aerosp Med Hum Perform. 2015; 86(4):357–365.

INTRODUCTION: Prospective memory allows people to complete intended tasks in the future. Prospective memory failures, such as pilots forgetting to inform pattern traffic of their locations, can have fatal consequences. The present research examined the impact of system factors (memory cue salience and workload) and individual differences (pilot age, cognitive health, and expertise) on prospective memory for communication tasks in the cockpit.METHODS: Pilots (N = 101) flew a Cessna 172 simulator at a non-towered aerodrome while maintaining communication with traffic and attending to flight parameters. Memory cue salience (the prominence of cues that signal an intended action) and workload were manipulated. Prospective memory was measured as radio call completion rates.RESULTS: Pilots’ prospective memory was adversely affected by low-salience cues and high workload. An interaction of cue salience, pilots’ age, and cognitive health reflected the effects of system and individual difference factors on prospective memory failures. For example, younger pilots with low levels of cognitive health completed 78% of the radio calls associated with low-salience memory cues, whereas older pilots with low cognitive health scores completed just 61% of similar radio calls.DISCUSSION: Our findings suggest that technologies designed to signal intended future tasks should target those tasks with inherently low-salience memory cues. In addition, increasing the salience of memory cues is most likely to benefit pilots with lower levels of cognitive health in high-workload conditions.Van Benthem KD, Herdman CM, Tolton RG, LeFevre J-A. Prospective memory failures in aviation: effects of cue salience, workload, and individual differences. Aerosp Med Hum Perform. 2015; 86(4):366–373.

INTRODUCTION: Due to the physical stresses to which they are subjected, military pilots may experience bruxism, an “oral parafunction.” Parafunction can cause masticatory muscle suffering and serious dental, periodontal, and temporomandibular joint damage. The aim of this pilot study was to analyze the temperature distribution in masticatory and upper trapezius muscles in a sample of bruxist air force pilots, to evaluate whether an occlusal splint would be able to induce skin temperature variations in the stomatognathic apparatus using the technology of infrared thermography.METHODS: A total of 11 male Italian Air Force pilots of high performance aircraft, ages from 27 to 40 yr (mean 34.91 ± 2.15 yr) with 1000–3000 flight hours, were enrolled in the study and analyzed using an infrared camera in order to evaluate the temperature of the masticatory muscles. All the recordings were taken on each subject using the same protocol with and without a temporary occlusal splint.RESULTS: The occlusal splint statistically increased each muscle temperature (0.10–0.20°C) on both the sides of the body. No statistically significant differences were found between the left and right muscles (asymmetries) before or after the wearing of the splint except for the anterior temporalis muscle. No significant improvement or variations in temperature symmetry of this muscle was found after the application of the splint.DISCUSSION: The use of an occlusal splint could help in increasing muscles temperatures in Air Force pilots with consequent relaxation of their facial muscular system.Baldini A, Nota A, Cioffi C, Ballanti F, Cozza P. Infrared thermographic analysis of craniofacial muscles in military pilots affected by bruxism. Aerosp Med Hum Perform. 2015; 86(4):374–378.

BACKGROUND: In-water resuscitation (IWR) is recommended in the 2010 guidelines of the European Resuscitation Council. As IWR represents a physical challenge to the rescuer, a novel Rescue Tube device with an integrated “Oxylator” resuscitator might facilitate IWR. The aim of the present study was the assessment of IWR using the novel Rescue Tube device.METHODS: Tidal and minute volumes were recorded using a modified Laerdal Resusci Anne mannequin. Furthermore, rescue time, water aspiration, submersions, and physical exertion were assessed. In this randomized cross-over trial, 17 lifeguards performed four rescue maneuvers over a 100-m distance in open water in random order: no ventilation (NV), mouth-to-mouth ventilation (MMV), Oxylator-aided mask ventilation (OMV), and Oxylator-aided laryngeal tube ventilation (OLTV).RESULTS: OLTV resulted in effective ventilation over the entire rescue distance with the highest mean minute volumes (NV 0, MMV 2.9, OMV 4.1, OLTV 7.6 L · min⁻¹). NV was the fastest rescue maneuver while IWR prolonged the rescue maneuver independently of the method of ventilation (mean total rescue time: NV 217, MMV 280, OMV 292, OLTV 290 s). Aspiration of substantial amounts of water occurred only during MMV (mean NV 20, MMV 215, OMV 15, OLTV 6 ml). NV and OLTV were rated as moderately challenging by the lifeguards, whereas MMV and OMV were rated as substantially demanding on a 0-10 visual analog scale (NV 5.3, MMV 7.8, OMV 7.6, OLTV 5.9).DISCUSSION: The device might facilitate IWR by providing effective ventilation with minimal aspiration and by reducing physical effort. Another advantage is the possibility of delivering 100% oxygen.Lungwitz YP, Nussbaum BL, Paulat K, Muth C-M, Kranke P, Winkler BE. A novel rescue-tube device for in-water resuscitation. Aerosp Med Hum Perform. 2015; 86(4):379–385.

INTRODUCTION: Many countries have hypergravity training centers using centrifuges for pilots to cope with a high gravity (G) environment. The high G training carries potential risk for the development of spinal injury. However, no studies evaluated the influence of centrifuge training on the spines of asymptomatic fighter pilots on a large scale.METHODS: Study subjects were 991 male fighter pilots with high G training at one institution. Subject variables included information about physical characteristics, flight hours of pilots prior to the training, and G force exposure related factors during training. The two dependent variables were whether the pilots developed acute spinal injury after training and the severity of the injury (major/minor).RESULTS: The incidence of acute spinal injury after high G training was 2.3% (23 of 991 subjects). There were 19 subjects who developed minor injury and 4 subjects who developed a herniated intervertebral disc, which is considered a major injury. In multivariate analysis, only the magnitude of G force during training was significantly related to the development of acute spinal injury. However, there was no significant factor related to the severity of the injury.DISCUSSION: These results suggest that high G training could cause negative effects on fighter pilots' spines. The magnitude of G force during training seemed to be the most significant factor affecting the occurrence of acute spinal injury.Kang K-W, Shin YH, Kang S. Acute spinal injury after centrifuge training in asymptomatic fighter pilots. Aerosp Med Hum Perform. 2015; 86(4):386–391.

BACKGROUND: This study investigates the effects of seasonality and altitude on sleep in extreme Antarctic conditions.METHODS: During summer and winter periods, 24 h of actimetric recordings were obtained at two different research stations, Dumont d’Urville (sea level altitude) and Concordia (corrected altitude 12,467 ft or 3800 m).RESULTS: During daytime, there were no altitude- or season-related differences in time spent at work, energy expenditure, or number of walking steps. During the nighttime however, total sleep time was longer (m = 427.4; SD = 42.4), sleep efficiency higher (m = 90; SD = 4.8), and wake after sleep onset shorter (m = 42.2; SD = 28.7) at sea level. Additionally, sleep fragmentation episodes and energy expenditure were higher during summer than winter periods.DISCUSSION: Our results show that dramatic variations in light exposure are not the only main factor affecting sleep quality in Antarctica, as altitude also markedly impacted sleep in these conditions. The effect of altitude-induced hypoxia should be taken into account in future investigations of sleep in extreme environments.Collet G, Mairesse O, Cortoos A, Tellez HF, Neyt X, Peigneux P, Macdonald-Nethercott E, Ducrot Y-M, Pattyn N. Altitude and seasonality impact on sleep in Antarctica. Aerosp Med Hum Perform. 2015; 86(4):392–396.

BACKGROUND: While the factors affecting fighter pilots’ G level tolerance have been widely accepted, the factors affecting fighter pilots’ G duration tolerance have not been well understood.METHODS: Thirty-eight subjects wearing anti-G suits were exposed to sustained high G forces using a centrifuge. The subjects exerted AGSM and decelerated the centrifuge when they reached the point of loss of peripheral vision. The G profile consisted of a +2.3 G onset rate, +7.3 G single plateau, and −1.6 G offset rate. Each subject’s G tolerance time was recorded and the relationship between the tolerance time and the subject's anthropometric and physiological factors were analyzed.RESULTS: The mean tolerance time of the 38 subjects was 31.6 s, and the min and max tolerance times were 20 s and 58 s, respectively. The correlation analysis indicated that none of the factors had statistically significant correlations with the subjects’ G duration tolerance. Stepwise multiple regression analysis showed that G duration tolerance was not dependent on any personal factors of the subjects. After the values of personal factors were simplified into 0 or 1, the t-test analysis showed that subjects’ heights were inversely correlated with G duration tolerance at a statistically significant level. However, a logistic regression analysis suggested that the effect of the height factor to a pilot's G duration tolerance was too weak to be used as a predictor of a pilot's G tolerance.CONCLUSION: Fighter pilots' G duration tolerance could not be predicted by pilots' anthropometric and physiological factors.Park M, Yoo S, Seol H, Kim C, Hong Y. Unpredictability of fighter pilots' G duration tolerance by anthropometric and physiological characteristics. Aerosp Med Hum Perform. 2015; 86(4):397–401.

INTRODUCTION: In jet pilots, the neck is stressed by dynamic loading and there is growing concern about possible neck damage in pilots of new agile aircraft. Jet pilots often report neck pain after flight so intense that their operational capability may be affected. However, there is no clear evidence of structural damage related to the operational exposure.METHODS: We compared 35 F-16 pilots with 35 age-matched Eurofighter Typhoon pilots. All subjects completed an anonymous questionnaire on their flight activity and neck pain.RESULTS: The incidence of neck pain in the F-16 group was 48.6% compared with 5.7% of the Typhoon group, significantly higher. In F-16 pilots, there was a significant association between neck pain and age over 30 yr, total flight hours, and flight hours exceeding 600.DISCUSSION: Our findings suggest that the risk of neck pain after flight is higher among F-16 pilots compared with Typhoon pilots. This could be due to several reasons, including the backward reclined seat of the F-16, which exposes the neck to the load in an unfavorable posture while moving the head during maneuvers at sustained high-G.Verde P, Trivelloni P, Angelino G, Morgagni F, Tomao E. Neck pain in F-16 vs. Typhoon fighter pilots. Aerosp Med Hum Perform. 2015; 86(4):402–406.

INTRODUCTION: With commercial spaceflight comes the possibility of spaceflight participants (SFPs) with significant medical conditions. Those with previously untested medical conditions, such as diabetes mellitus (DM) and the use of indwelling medical devices, represent a unique challenge. It is unclear how SFPs with such devices will react to the stresses of spaceflight. This case report describes two subjects with Type I DM using insulin pumps who underwent simulated dynamic phases of spaceflight via centrifuge G force exposure.CASE REPORT: Two Type I diabetic subjects with indwelling Humalog insulin pumps, a 23-yr-old man averaging 50 u of Humalog daily and a 27-yr-old man averaging 60 u of Humalog daily, underwent seven centrifuge runs over 48 h. Day 1 consisted of two +G_z runs (peak = +3.5 G_z, run 2) and two +G_x runs (peak = +6.0 G_x, run 4). Day 2 consisted of three runs approximating suborbital spaceflight profiles (combined +G_x and +G_z). Data collected included blood pressure, electrocardiogram, pulse oximetry, neurovestibular evaluation, and questionnaires regarding motion sickness, disorientation, greyout, and other symptoms. Neither subject experienced adverse clinical responses to the centrifuge exposure. Both maintained blood glucose levels between 110–206 mg · dl⁻¹.DISCUSSION: Potential risks to SFPs with insulin pump dependent DM include hypo/hyperglycemia, pump damage, neurovestibular dysfunction, skin breakdown, and abnormal stress responses. A search of prior literature did not reveal any previous studies of individuals with DM on insulin pumps exposed to prolonged accelerations. These cases suggest that individuals with conditions dependent on continuous medication delivery might tolerate the accelerations anticipated for commercial spaceflight.Levin DR, Blue RS, Castleberry TL, Vanderploeg JM. Tolerance of centrifuge-simulated suborbital spaceflight in subjects with implanted insulin pumps. Aerosp Med Hum Perform. 2015; 86(4):407–409.

INTRODUCTION: Future commercial spaceflight participants (SFPs) with conditions requiring personal medical devices represent a unique challenge. The behavior under stress of cardiac implanted devices (CIDs) such as pacemakers is of special concern. No known data currently exist on how such devices may react to the stresses of spaceflight. We examined the responses of two volunteer subjects with CIDs to G forces in a centrifuge to evaluate how similar potential commercial SFPs might tolerate the forces of spaceflight.CASE REPORT: Two subjects, 75- and 79-yr-old men with histories of atrial fibrillation and implanted dual-lead, rate-responsive pacemakers, underwent seven centrifuge runs over 2 d. Day 1 consisted of two +G_z runs (peak = +3.5 G_z, run 2) and two +G_x runs (peak = +6.0 G_x, run 4). Day 2 consisted of three runs approximating suborbital spaceflight profiles (combined +G_x/+G_z). Data collected included blood pressures, electrocardiograms, pulse oximetry, neurovestibular exams, and postrun questionnaires regarding motion sickness, disorientation, greyout, and other symptoms. Despite both subjects’ significant medical histories, neither had abnormal physiological responses. Post-spin analysis demonstrated no lead displacement, damage, or malfunction of either CID.DISCUSSION: Potential risks to SFPs with CIDs include increased arrhythmogenesis, lead displacement, and device damage. There are no known prior studies of individuals with CIDs exposed to accelerations anticipated during the dynamic phases of suborbital spaceflight. These cases demonstrate that even individuals with significant medical histories and implanted devices can tolerate the acceleration exposures of commercial spaceflight. Further investigation will determine which personal medical devices present significant risks during suborbital flight and beyond.Blue RS, Reyes DP, Castleberry TL, Vanderploeg JM. Centrifuge-simulated suborbital spaceflight in subjects with cardiac implanted devices. Aerosp Med Hum Perform. 2015; 86(4):410–413.

Ramage MH. You’re the flight surgeon: eosinophilic esophagitis. Aerosp Med Hum Perform. 2015; 86(4):418–421.

Moore JL, Jackson CR, Ellis JC, Norrid C. You’re the flight surgeon: myelolipoma. Aerosp Med Hum Perform. 2015; 86(4):421–423.