INTRODUCTION: The ocular effects of excess solar radiation exposure are well documented. Recent evidence suggests that ocular ultraviolet radiation (UVR) exposure to professional pilots may fall outside international guideline limits unless eye protection is used. Nonprescription sunglasses should be manufactured to meet either international or national standards. The mean increase in UVR and blue light hazards at altitude has been quantified and the aim of this research was to assess the effectiveness of typical pilot sunglasses in reducing UVR and blue light hazard exposure in flight.METHOD: A series of sunglass filter transmittance measurements were taken from personal sunglasses (N = 20) used by pilots together with a series of new sunglasses (N = 18).RESULTS: All nonprescription sunglasses measured conformed to international standards for UVR transmittance and offered sufficient UVR protection for pilots. There was no difference between right and left lenses or between new and used sunglasses. All sunglasses offered sufficient attenuation to counter the mean increase in blue light exposure that pilots experience at altitude, although used sunglasses with scratched lenses were marginally less effective. One pair of prescription sunglasses offered insufficient UVR attenuation for some flights, but would have met requirements of international and national standards for UV-A transmittance. This was likely due to insufficient UVR blocking properties of the lens material.CONCLUSIONS: Lenses manufactured to minimally comply with standards for UVR transmittance could result in excess UVR exposure to a pilot based on in-flight irradiance data; an additional requirement of less than 10% transmittance at 380 nm is recommended.Chorley AC, Lyachev A, Higlett MP, Khazova M, Benwell MJ, Evans BJW. Sunglass filter transmission and its operational effect in solar protection for civilian pilots. Aerosp Med Hum Perform. 2016; 87(5):436–442.

BACKGROUND: Chronic unloading and restricted activity are distinctly different processes, i.e., unloading completely removes the load on postural muscles, whereas restricted activity allows for loading of postural muscles. There are limited data available on the effects of restricted activity on skeletal muscles. Thus the effects of restricted activity on the properties of the slow soleus and fast plantaris muscles in rats were examined.METHODS: Eight-week-old rats were housed for 21 d in normal-sized (control group) or in small-sized (restricted group) cages.RESULTS: Decreased mRNA levels of peroxisome proliferator-activated receptor γ coactivator-1α (81 and 85% of control values) and reduced succinate dehydrogenase activity (85 and 88% of control values) were observed in the soleus and the plantaris muscles of the restricted group, respectively. Increased mRNA levels of forkhead box-containing protein O1 (128% of control values), decreased muscle weight (74% of control values), and reduced cross-sectional areas of type IIA (89% of control values) and type IIB (80% of control values) fibers were observed in the plantaris muscle of the restricted group.DISCUSSION: Restricted activity decreased the mRNA levels of peroxisome proliferator-activated receptor γ coactivator-1α and increased the mRNA levels of forkhead box-containing protein O1, which are associated with reduced oxidative capacity and atrophy, respectively, in the muscles. The plantaris muscle was more affected by restricted activity than the soleus muscle, most likely reflecting a greater relative change in the normal activity pattern in the fast than slow plantarflexor muscle.Takemura A, Roy RR, Edgerton VR, Ishihara A. Biochemical adaptations in a slow and a fast plantarflexor muscle of rats housed in small cages. Aerosp Med Hum Perform. 2016; 87(5):443–448.

INTRODUCTION: The objective was to determine the effects of 6 mo of microgravity exposure on conduit artery diameter and wall thickness.METHODS: Diagnostic images of the common carotid artery (CC) and superficial femoral artery (FA) were obtained using echography which astronauts performed on themselves after receiving minimal training in the use of ultrasound imaging. Echographic video was recorded using a volume capture method directed by a trained sonographer on the ground through videoconferencing. Vessel properties were later assessed by processing the downlinked video. Data were collected from 10 astronauts who performed the echographic video capture at the beginning of the spaceflight (day 15) and near the end of the spaceflight (day 115 to 165). In-flight and postflight measurements were compared to preflight assessments.RESULTS: No significant changes with spaceflight were found for CC and FA diameter. Intima-media thickness (IMT) of the CC was found to be significantly increased (12% ± 4) in all astronauts during the spaceflight (early and late flight) and remained elevated 4 d after returning to Earth. Similarly, FA IMT was increased during the flight but returned to preflight levels 4 d postflight.CONCLUSION: The experiment demonstrated that, using the volume capture method of echography, untrained astronauts were able to capture enough echographic data to display vessel images of good quality for analysis. The increase in both CC and FA IMT during the flight suggest an adaptation to microgravity and to the confined environment of spaceflight which deserves further investigation.Arbeille P, Provost R, Zuj K. Carotid and femoral artery intima-media thickness during 6 months of spaceflight. Aerosp Med Hum Perform. 2016; 87(5):449–453.

BACKGROUND: One disorienting movement pattern, common during flight, is the entering of a coordinated turn. While the otoliths persistently sense upright head position, the change in roll attitude constitutes a semicircular canal stimulus. This sensory conflict also arises during acceleration in a swing-out gondola centrifuge. From a vestibular viewpoint there are, however, certain differences between the two stimulus situations; the aim of the present study was to elucidate whether these differences are reflected in the perceived roll attitude.METHODS: Eight nonpilots were tested in a centrifuge (four runs) and during flight (two turns). The subjective visual horizontal (SVH) was measured using an adjustable luminous line in darkness. The centrifuge was accelerated from stationary to 1.56 G (roll 50°) within 7 s; the duration of the G plateau was 5 min. With the aircraft, turns with approximately 1.4 G (45°) were entered within 15 s and lasted for 5 min. Tilt perception (TP) was defined as the ratio of SVH/real roll tilt; initial and final values were calculated for each centrifugation/turn.RESULTS: In both systems there was a sensation of tilt that declined with time. The initial TP was (mean ± SD): 0.40 ± 0.27 (centrifuge) and 0.37 ± 0.30 (flight). The final TP was 0.20 ± 0.26 and 0.17 ± 0.19, respectively. Both initial and final TP correlated between the two conditions.CONCLUSION: The physical roll tilt is under-estimated to a similar degree in the centrifuge and aircraft. Also the correspondence at the individual level suggests that the vestibular dilemma of coordinated flight can be recreated in a lifelike manner using a gondola centrifuge.Tribukait A, Ström A, Bergsten E, Eiken O. Vestibular stimulus and perceived roll tilt during coordinated turns in aircraft and gondola centrifuge. Aerosp Med Hum Perform. 2016; 87(5):454–463.

BACKGROUND: In a previous study, pressurized sleeves and gloves were found to substantially diminish or eliminate G-induced arm pain. Since this equipment presumably acts similarly to a G suit for the arms and hands, it was hypothesized that higher inflation pressures might provide an additional increment of G protection.METHODS: In a human-rated centrifuge, 15 well trained subjects using Combat Edge and ATAGS G-protective equipment were exposed to gradual and rapid onset relaxed G exposures as well as rapid onset straining and simulated aerial combat maneuver G exposures up to + 9 G_z with and without pressurized sleeves and gloves.RESULTS: The pressurized sleeves and gloves did not show any improvement in G tolerance or endurance compared to the control. However, significantly lower heart rates (6–12%) and subjective effort (11%), along with slightly less peripheral vision loss, suggest a decreased work load when wearing the pressurized sleeves and gloves. A trend to shorter time on target in a tracking task was found with the pressurized sleeves and gloves, likely due to decreased mobility of the hands, thus affecting control stick input.CONCLUSIONS: G tolerance and endurance were not improved by the pressurized sleeves and gloves. However, a lower heart rate and a decreased subjective effort level and peripheral vision loss indicated that the subjects did not have to work as hard with this equipment.Morgan TR, Balldin U, Fischer JR. G protection when adding pressurized sleeves and gloves to a representative G-suit ensemble. Aerosp Med Hum Perform. 2016; 87(5):464–469.

BACKGROUND: Biological specimens from pilots fatally injured in civil aviation accidents are analyzed for ethanol and drugs at the Civil Aerospace Medical Institute (CAMI). Prevalence of these substances in the pilots has been evaluated at 5-yr intervals since 1989. In continuation, a fifth 5-yr study (2009–2013) was conducted.METHODS: The CAMI toxicology/medical certification and National Transportation Safety Board (NTSB) aviation accident databases were searched.RESULTS: During 2009–2013, samples from 1169 pilots were analyzed. Aircraft involved in the accidents were primarily operating under general aviation. Most airmen were private pilots and held third-class medical certificates. In relation to the first 5-yr (1989–1993) period, the pilot fatality cases decreased by 37% and the presence of ethanol and/or drugs in the pilots increased by 239% in the fifth 5-yr period. The ethanol usage was unchanged, but increases were 267% and 583% with illicit and prescription drugs, respectively. The use of ethanol and/or drugs by aviators, along with underlying medical conditions, was determined by the NTSB to be cause/factors in 5% of the accidents.CONCLUSION: The observed decrease in the fatality cases does not necessarily suggest the decrease in aviation accidents, as active airmen numbers also declined. The increase in the drug positive cases is primarily attributed to the continuous rise in the use of prescription drugs. Although prevalence of ethanol and drugs has been evaluated in fatally injured aviators, such evaluation has not been performed in active pilots not involved in accidents. This type of comparative study would be crucial in assessing aviation safety.Chaturvedi AK, Craft KJ, Hickerson JS, Rogers PB, Canfield DV. Ethanol and drugs found in civil aviation accident pilot fatalities, 1989–2013. Aerosp Med Hum Perform. 2016; 87(5):470–476.

INTRODUCTION: The use of hyperbaric oxygen (O₂) as a therapeutic agent carries with it the risk of central nervous system (CNS) O₂ toxicity.METHODS: To further the understanding of this risk and the nature of its molecular mechanism, a review was conducted on the literature from various fields.RESULTS: Numerous physiological changes are produced by increased partial pressures of oxygen (Po₂), which may ultimately result in CNS O₂ toxicity. The human body has several equilibrated safeguards that minimize effects of reactive species on neural networks, believed to play a primary role in CNS O₂ toxicity. Increased partial pressure of oxygen (Po₂) appears to saturate protective enzymes and unfavorably shift protective reactions in the direction of neural network overstimulation. Certain regions of the CNS appear more susceptible than others to these effects. Failure to decrease the elevated Po₂ can result in a tonic-clonic seizure and death. Randomized, controlled studies in human populations would require a multicenter trial over a long period of time with numerous endpoints used to identify O₂ toxicity.CONCLUSIONS: The mounting scientific evidence and apparent increase in the number of hyperbaric O₂ treatments demonstrate a need for further study in the near future.Manning EP. Central nervous system oxygen toxicity and hyperbaric oxygen seizures. Aerosp Med Hum Perform. 2016; 87(5):477–486.

BACKGROUND: Bicuspid aortic valve disease (BAV) is the most common cardiac valve pathology. BAV is associated with aortic root disorders. The literature has few case reports identifying this condition during routine physical exam.CASE REPORT: A 42-yr-old military reservist flight medic presented for his annual military flight physical. He was found to have a faint cardiac murmur. His past family and medical history were remarkable for familial essential hypertension and being told at age 9 that he had a “murmur.” He was referred for cardiology consultation, echocardiography, stress testing, and a computerized tomography angiogram (CTa), which identified BAV with a 4.3-cm aortic root aneurysm. A follow-up at 1 yr was recommended. In the interim he developed severe aortic valve insufficiency, a 4.6-cm aortic root aneurysm. The valve and aortic root were repaired and a single left anterior descending coronary artery lesion was bypassed during surgery. The flight medic made a full recovery but was not returned to flight status.DISCUSSION: This case emphasizes the importance of periodic reassessment by thorough history and careful cardiac auscultation during flight physicals. BAV aortopathy is an uncommon condition seen in the military aviation community. Most flight surgeons will not have the opportunity to identify it specifically via auscultation. This patient had over nine annual flight physicals prior to the one reported and no pathology was ever identified through routine auscultation. The potential role of point-of-care ultrasound (POCUS) for survey of vascular and valve status of aviation personnel merits further research.Fredricks TR, Benseler JS. Aortic root aneurism found in a 42-year-old epitomizes the importance of auscultation in routine exams. Aerosp Med Hum Perform. 2016; 87(5):487–492.

BACKGROUND: This case study documents the training, laboratory preparation, and in-race performance data from Great Britain’s top finisher in the 13^th edition of the UVU North Pole Marathon.CASE REPORT: We report data from a preparatory laboratory test in simulated cold conditions (−15°C) with and without wind chill during high- and low-intensity expected ‘race pace’ running. These tests examined the adequacy of the selected clothing assembly and provided recommendations for the race. The tests established that there was no risk of hypothermia, as the clothing assembly provided too much insulation; terminal rectal temperature was 39.25°C. Skin temperature (T_sk) data revealed no impending risk of frostbite; nadir T_sk was 20.2°C at the hamstring. Oxygen consumption data revealed the self-selected high intensity was potentially not sustainable based on estimates of substrate utilization. We recommended: 1) a maximum running speed; 2) some of the clothing base layers could be removed pre-race; 3) vents and/or zips could be used to offload or retain heat; and 4) an even pacing profile should be adopted.DISCUSSION: The participant completed the race in 6:55:24 (h:mm:ss) in temperatures of −41°C. GPS data revealed a positive pacing template (i.e., marginally quicker in the first half). Neither hypothermia nor frostbite occurred. Peak pace from the laboratory tests was not consistently exceeded. Marathon performance can be undertaken in one of the world’s most inhospitable environments when careful consideration is given to clothing insulation and exercise intensity by planning for the dynamic thermal changes that may occur as the race ensues.Barwood MJ, Burrows H, Cessford J. North Pole Marathon laboratory lessons and field success. Aerosp Med Hum Perform. 2016; 87(5):493–497.

INTRODUCTION: Hypoxia caused by high altitude exposure can impair cerebral and mental functions. Blood flow and oxygenation of the buccal tissue can be reliable markers to detect hypoxia. In this study, near infrared spectroscopy was used in combination with a novel optical probe to evaluate the applicability of the novel probe in measuring hypoxia markers in buccal tissue under a hypoxic condition.METHODS: Six healthy participants were tested at altitudes from 2000 to 16,000 ft inside a hypobaric chamber. The buccal reference measurements of blood flow and oxygen saturation were synchronized with the spectral measurements of the novel near infrared probe and the relationship between the reference measurements and spectral data were evaluated by multivariate partial least square method. In addition, finger oxygen saturation was measured during the experiment and the recordings were compared with buccal oxygen saturation.RESULTS: The spectral analysis illustrated that the spectral data from the near infrared probe correlated strongly with the absorption features of both buccal flow and oxygenation measured by the reflectance sensors (average R² = 0.89). The results showed probably overestimated values for buccal oxygen saturation recorded by the reference pulse oximeter in comparison with finger oxygen saturation, with the mean difference increasing from 1.8% at 2000 ft to 11.4% at 16,000 ft.CONCLUSION: The novel near infrared probe showed promising results for simultaneous measurement of blood flow and oxygen saturation in the buccal tissue. The suggested method can be used as a new technique for early indication of hypoxia in future clinical applications.Amini M, Hisdal J, Gjøvaag T, Kapetanovic N, Strand T-E, Owe JO, Hørthe JR, Mirtaheri P. Near-infrared spectra in buccal tissue as a marker for detection of hypoxia. Aerosp Med Hum Perform. 2016; 87(5):498–504.

In September 2012, the Aerospace Medical Association published and distributed recommendations from its Pilot Mental Health Working Group to improve awareness and identification of pilot mental health issues during the aeromedical assessment of pilots. Following the crash of Germanwings Flight 9525 in March 2015 with pilot suicide as the probable cause, the Pilot Mental Health Working Group reconvened to review their recommendations. As a result, the working group revised the recommendations which are provided here and which were distributed worldwide. The Working Group continues to emphasize the importance of assessing and optimizing pilot mental health, while providing additional recommendations on building trust and rapport between the aeromedical examiner and the pilot, on utilizing aviation mental health and aeromedical specialists, and on the balance between medical confidentiality and risk to public safety. The working group encourages all organizations involved in flight safety to review and consider implementing these recommendations within their usual operations.Aerospace Medical Association Working Group on Pilot Mental Health. Pilot mental health: expert working group recommendations – revised 2015. Aerosp Med Hum Perform. 2016; 87(5):505–507.

Rohrer RJ, Ostrofe AA, Zenk RL. You’re the flight surgeon: atrial fibrillation. Aerosp Med Hum Perform. 2016; 87(5):508–510.

Morgan L, Arora N, Fernelius C. You’re the flight surgeon: mycobacterium infection following tattooing. Aerosp Med Hum Perform. 2016; 87(5):510–512.