INTRODUCTION: Increased white matter hyperintensities (WMH) on magnetic resonance imaging (MRI) brain scans of high altitude aircrew and altitude chamber workers indicate that exposure to low ambient pressure (hypobaria) promotes white matter injury. If associated with frequent
decompression stress then experienced divers should also exhibit more WMH, yet published case-control studies are inconsistent. This meta-analysis evaluated the prevalence of WMH in healthy divers and controls.METHODS: Eligible studies compared experienced divers (or hyperbaric
workers) without neurological decompression illness with nondiving controls, identified from multiple database searches and reference list reviews. Studies were scored for sample size, recruitment bias, control matching, MRI sensitivity, and confounding factors before grading as low, medium,
or high quality. Meta-analysis of odds ratios (OR) with 95% confidence intervals (CI) was conducted on all data using a random effects model and repeated after exclusion of low-quality studies.RESULTS: There were 11 eligible studies identified. After data adjustment to exclude diving
accidents, these encompassed 410 divers and 339 controls, of which 136 (33%) and 79 (23%), respectively, exhibited WMH (OR 1.925, 95% CI 1.088 to 3.405). Excluding four low-quality studies eliminated meta-analysis heterogeneity, with 98 of 279 divers (35%) and 44 of 232 controls (19%) exhibiting
WMH (OR 2.654, 95% CI 1.718 to 4.102).CONCLUSIONS: Results suggest that repeated hyperbaric exposure increases the prevalence of white matter injury in experienced healthy divers without neurological decompression illness. This is consistent with reports of increased WMH in asymptomatic
altitude workers and an association with intensity of dysbaric exposure.Connolly DM, Lee VM. Odds ratio meta-analysis and increased prevalence of white matter injury in healthy divers. Aerosp Med Hum Perform. 2015; 86(11):928–935.
INTRODUCTION: Neck and back pain in fighter pilots remains a serious occupational problem. We hypothesized that recent advances such as the joint helmet mounted cueing system (JHMCS) in modern air combat might contribute to the development of spinal complaints in F-16 pilots.METHODS:
Surveyed were 59 F-16 pilots of the Royal Netherlands Air Force who were compared to 49 F-16 pilots who filled in a similar questionnaire in 2007. The prevalence of neck and back pain, work situations, and capacity of the pilot were analyzed.RESULTS: The self-reported 1-yr prevalence
of regular or continuous neck and lower back pain in 2014 were 22% and 31%, respectively, compared to both being 12% in 2007. Age, military flying experience, total number of flying hours, flying hours on the F-16, and total number of hours flown with night vision goggles (NVG) were significantly
higher in 2014. In 2014, 95% flew with JHMCS, compared to 0% in 2007. Flying with JHMCS (88%), NVG (88%), type of flight (63%), and sitting posture (50%) were the most reported causes of flight-related neck pain. Sitting posture (89%), duration of flight (56%), and seat (44%) were among the
reported causes of back pain.DISCUSSION: The increasing trend of neck and lower back pain might be caused by multiple changes in both the work situation and capacity of the pilots since 2007. Future innovations will increase the load on the pilot’s spine. To successfully address
their spinal problems in the future, fighter pilots must be monitored continuously.Thoolen SJJ, van den Oord MHAH. Modern air combat developments and their influence on neck and back pain in F-16 pilots. Aerosp Med Hum Perform. 2015; 86(11):936–941.
BACKGROUND: Sustained high-level cognitive performance is of paramount importance for the success of space missions, which involve environmental, physiological, and psychological stressors that may affect brain functions. Despite subjective symptom reports of cognitive fluctuations
in spaceflight, the nature of neurobehavioral functioning in space has not been clarified.METHODS: We developed a computerized cognitive test battery (Cognition) that has sensitivity to multiple cognitive domains and was specifically designed for the high-performing astronaut
population. Cognition consists of 15 unique forms of 10 neuropsychological tests that cover a range of cognitive domains, including emotion processing, spatial orientation, and risk decision making. Cognition is based on tests known to engage specific brain regions as evidenced
by functional neuroimaging. Here we describe the first normative and acute total sleep deprivation data on the Cognition test battery as well as several efforts underway to establish the validity, sensitivity, feasibility, and acceptability of Cognition.RESULTS: Practice
effects and test-retest variability differed substantially between the 10 Cognition tests, illustrating the importance of normative data that both reflect practice effects and differences in stimulus set difficulty in the population of interest. After one night without sleep, medium
to large effect sizes were observed for 3 of the 10 tests addressing vigilant attention (Cohen’s d = 1.00), cognitive throughput (d = 0.68), and abstract reasoning (d = 0.65).CONCLUSIONS: In addition to providing neuroimaging-based novel information on the effects of spaceflight
on a range of cognitive functions, Cognition will facilitate comparing the effects of ground-based analogues to spaceflight, increase consistency across projects, and thus enable meta-analyses.Basner M, Savitt A, Moore TM, Port AM, McGuire S, Ecker AJ, Nasrini J, Mollicone DJ, Mott
CM, McCann T, Dinges DF, Gur RC. Development and validation of the Cognition test battery for spaceflight. Aerosp Med Hum Perform. 2015; 86(11):942–952.
INTRODUCTION: There is good evidence that long term exposure to ultraviolet (UV) radiation increases the risk of cataracts. The ‘blue light hazard’ is considered a risk factor for retinal changes similar to those seen in macular degeneration. Previous studies ascertaining
the prevalence of radiation related ocular disease in pilot cohorts have not considered use of solar eye protection. The aim of this study was to explore pilot use of sunglasses and other solar eye protection habits and to gain insight into the difficulties encountered managing sunlight on
the flight deck. Additionally, the prevalence of radiation related ocular pathology in the study group was calculated.METHODS: A web based questionnaire was developed and administered to a large population of current UK professional pilots.RESULTS: There were 2917 respondents
who completed the questionnaire, demonstrating a wide range of sunglass use during flight. A number of barriers to sunglass use were identified, the most prevalent being the requirement for corrective lenses to be used. Pilots most commonly increase sunglass use due to ocular health concerns.
A high level of dissatisfaction with standard aircraft sun protection systems was reported. Long haul airline pilots were the highest users of nonstandard sunlight blocking strategies. No correlation between reported pathology and flying experience was found.DISCUSSION: The use
of sunglasses during flight is complex; however, a number of practical recommendations can be made to increase the success for those pilots who wish to use sunglasses more. Aircraft manufacturers should consider how greater control of cockpit sunlight levels can be achieved.Chorley AC,
Evans BJW, Benwell MJ. Solar eye protection practices of civilian aircrew. Aerosp Med Hum Perform. 2015; 86(11):953–961.
OBJECTIVE: The aim of this study was to provide information on the occurrence of spinal pain, i.e., low back and neck pain, among commercial helicopter pilots, along with possible associations between pain and anthropometric and demographic factors and flying exposure.METHODS:
Data were collected through a subjective and retrospective survey among all the 313 (294 men, 19 women) full-time pilots employed by two helicopter companies. A questionnaire was used to assess the extent of spinal complaints in a transient and recurrent pain pattern along with information
on physical activities, occupational flying experience, and airframes.RESULTS: The survey had 207 responders (194 men, 13 women). The pilots had extensive flying experience. Spinal pain was reported by 67%. Flying-related transient pain was reported among 50%, whereas recurrent
spinal pain, not necessarily associated with flying, was reported by 52%. Women experienced more pain, but sample size prevented further conclusions. Male pilots reporting any spinal pain flew significantly more hours last year (median 500 h, IQR 400–650) versus men with no pain (median
445 h, IQR 300–550). Male pilots with transient or recurrent spinal pain did not differ from nonaffected male colleagues in the measured parameters.CONCLUSION: Spinal pain is a frequent problem among male and female commercial helicopter pilots. For men, no significant associations
were revealed for transient or recurrent spinal pain with age, flying experience in years, total hours, annual flying time, type of aircraft, or anthropometric factors except for any spinal pain related to hours flown in the last year.Andersen K, Baardsen R, Dalen I, Larsen JP. Recurrent
and transient spinal pain among commercial helicopter pilots. Aerosp Med Hum Perform. 2015; 86(11):962–969.
BACKGROUND: Due to the recent increase of metabolic syndrome (MetS) in the Korean population, this study was performed to investigate the prevalence of MetS among Republic of Korea (ROK) Air Force military aviators and its relationship with clinical markers.METHODS:
A cross-sectional study was performed among 911 aviators who filled out the lifestyle questionnaire and underwent medical examinations at the ROK Air Force Aerospace Medical Center. Clinical markers of aviators with MetS were investigated and odds ratios were calculated.RESULTS:
Among the 911 aviators, 90 (9.9%) were found to have MetS and the prevalence of subcomponents were: 31.7% elevated blood pressure, 25.3% elevated waist circumference, 19.0% impaired glucose tolerance, 16.6% elevated triglycerides, 7.9% reduced high density lipoprotein (HDL) cholesterol. Among
aviators, a significant statistical association was found between the diagnosis of MetS with the highest quartile of uric acid, white blood cell (WBC) count, and alanine transaminase (ALT) level. Adjusted odds ratio of MetS was 8.88 (3.16 ∼24.99) if all three clinical markers were at highest
quartile range.DISCUSSION: Despite the relatively low prevalence of MetS in ROK Air Force aviators, further preventive measures are required as the prevalence is expected to increase in the future. Aviators with high levels of WBC count, uric acid, and ALT should be examined for
MetS. Further comprehensive cohort study is required to link the elevation of clinical markers and development of MetS.Rhee C, Kim J, Kim J-Y, Chang E, Park S, Lee W, Kang H. Clinical markers associated with metabolic syndrome among military aviators. Aerosp Med Hum Perform. 2015;
86(11):970–975.
BACKGROUND: The purpose of this study was to quantify the efficacy of using exercise to alleviate the impairments in mood state associated with hypoxic exposure.METHODS: Nineteen young, healthy men completed Automated Neuropsychological Assessment Metrics-4th
Edition (ANAM4) versions of the mood state test before hypoxia exposure, after 60 min of hypoxia exposure (12.5% O2), and during and after two intensities of cycling exercise (40% and 60% adjusted Vo2max) under the same hypoxic conditions. Peripheral oxygen saturation
(Spo2) and regional cerebral oxygen saturation (rSo2) were continuously monitored.RESULTS: At rest in hypoxia, Total Mood Disturbance (TMD) was significantly increased compared to baseline in both the 40% and 60% groups. TMD was significantly decreased during
exercise compared to rest in hypoxia. TMD was also significantly decreased during recovery compared to rest in hypoxia. Spo2 significantly decreased at 60 min rest in hypoxia, during exercise, and recovery compared to baseline. Regional cerebral oxygen saturation was also reduced
at 60 min rest in hypoxia, during exercise, and recovery compared to baseline.DISCUSSION: The current study demonstrated that exercise at 40% and 60% of adjusted Vo2max attenuated the adverse effects of hypoxia on mood. These findings may have significant applied value,
as negative mood states are known to impair performance in hypoxia. Further studies are needed to replicate the current finding and to clarify the possible mechanisms associated with the potential benefits of exercise on mood state in normobaric hypoxia.Seo Y, Fennell C, Burns K, Pollock
BS, Gunstad J, McDaniel J, Glickman E. Exercise improves mood state in normobaric hypoxia. Aerosp Med Hum Perform. 2015; 86(11):976–981.
BACKGROUND: Missions to terrestrial destinations (i.e., asteroids, the Moon, and Mars) will consist of physically challenging mission-critical tasks. These tasks, coupled with the negative physiological effects of prolonged microgravity exposure, create a plausible situation
in which physical requirements may exceed an astronaut’s physical capacity. Therefore, the objective of the current study was to evaluate the association of aerobic fitness and muscular strength parameters with performance during two field tests designed to simulate upper-body mission-critical
activities.METHODS: There were 70 subjects who completed a material transport field test requiring the loading, transport, and unloading of geological samples and a device operations field test consisting of tasks associated with equipment set-up and the operations of controls and
valves. The relationships between test duration and the following measurements were determined: running Vo2max, gas exchange threshold (GET), speed at Vo2max (s-Vo2max), highest sustainable rate of aerobic metabolism [critical speed (CS)], and the finite distance
that could be covered above CS (D’); and arm cranking Vo2peak, GET, critical power (CP), and the finite work that can be performed above CP (W’).RESULTS: CP (r = −0.66), CS (r = −0.56), and arm cranking Vo2peak (r = −0.54) were
most strongly correlated with the material transport field test and decision tree analysis revealed CP as the best predictor of performance. For the device operations field test, CP (r = −0.70), CS (r = −0.62), and arm cranking peak power output (r = −0.56) were significant
predictors.DISCUSSION: Arm cranking tests are strongly associated with upper-body dependent tasks, highlighting that the nature of mission tasks needs to be considered when evaluating astronaut physical capacity.Ade CJ, Broxterman RM, Craig JC, Schlup SJ, Wilcox SL, Barstow
TJ. Standardized exercise tests and simulated terrestrial mission task performance. Aerosp Med Hum Perform. 2015; 86(11):982–989.
BACKGROUND: Self-reported occupational exposures are often used in epidemiological studies when actual exposure measurements are unavailable, which could cause measurement error and bias study results. This study provides a numeric example of this potential bias.METHODS:
A study of block hours and preterm birth was used as an illustrative example. This study included 577 flight attendants, ages 18-45 yr, who gave birth to a term (37 or greater gestational weeks) or preterm (20-36 gestational weeks) infant between 1992 and 1996. Flight attendants self-reported
the number of block hours flown during the first trimester of pregnancy; the number of block hours flown during the first trimester of pregnancy was also calculated from airline records. No adjustment for confounding was performed for this illustrative example.RESULTS: Although
flight attendants having term and preterm births self-reported similar hours worked during the first trimester (median 213 vs. 215 block hours), airline records showed that flight attendants having term births worked more hours than those having preterm births (median 146 vs. 104 block hours).
Using self-reported block hours, there was no association between block hours and preterm birth; when using airline records, an inverse association was observed.DISCUSSION: In this example, differential measurement error from use of self-reported block hours obscured an inverse
association apparent when using airline records, demonstrating the importance of accurate exposure assessment for identifying occupational risk factors for health outcomes.Johnson CY, Grajewski B. Bias from differential exposure measurement error in a study of flight attendants.
Aerosp Med Hum Perform. 2015; 86(11):990–993.
BACKGROUND: A case of unilateral optic neuropathy secondary to barotrauma following a medial orbital wall fracture is presented.CASE REPORT: A 41-yr-old U.S. Air Force aviator presented for a routine periodic health assessment. Evaluation uncovered a suspected acquired
color deficiency in the right eye (OD). Subsequent discussions with the patient revealed a history of eye pain, redness, and proptosis during a flight overseas several years earlier. Local ocular examination demonstrated asymmetric optic nerve cupping, optic nerve pallor OD, a mild asymmetric
color deficit, and a significant visual field defect OD. Evaluation with magnetic resonance imaging revealed findings consistent with an old medial orbital wall fracture OD and optic nerve findings consistent with optic neuropathy. Follow-up evaluation by neurology and otorhinolaryngology
demonstrated only extensive sinus pathology. Based upon these findings, it is postulated that the member suffered a medial orbital wall fracture at altitude during ascent caused by expanding ethmoid sinus gases due to abnormal sinus anatomy with subsequent right optic nerve injury leading
to an optic neuropathy and subsequent visual sequelae.DISCUSSION: This case demonstrates one possible complication of active sinus disease while working in the aerospace environment. Several case reports have been published demonstrating the potential link between eye injuries and
working in an environment with fluctuating atmospheric pressure. However, literature addressing the specific in-flight environment causing such complications is lacking. Furthermore, the case supports the need for versatility and a broad knowledge base in practicing flight surgeons to evaluate
ocular pathology.Powell MR, Hurley LD, Richardson TC. An unusual complication of barotrauma at altitude. Aerosp Med Hum Perform. 2015; 86(11):994–998.
INTRODUCTION: Commercial spaceflight participants (SFPs) will introduce new medical challenges to the aerospace community, with unique medical conditions never before exposed to the space environment. This is a case report regarding the response of a subject with multiple cardiac
malformations, including aortic insufficiency, pulmonary atresia, pulmonary valve replacement, ventricular septal defect (post-repair), and pulmonary artery stenosis (post-dilation), to centrifuge acceleration simulating suborbital flight.CASE REPORT: A 23-yr-old man with a history
of multiple congenital cardiac malformations underwent seven centrifuge runs over 2 d. Day 1 consisted of two +Gz runs (peak = +3.5 Gz, run 2) and two +Gx runs (peak = +6.0 Gx, run 4). Day 2 consisted of three runs approximating suborbital spaceflight
profiles (combined +Gx and +Gz). Data collected included blood pressure, electrocardiogram, pulse oximetry, neurovestibular exams, and post-run questionnaires regarding motion sickness, disorientation, greyout, and other symptoms. Despite the subject’s significant
medical history, he tolerated the acceleration profiles well and demonstrated no significant abnormal physiological responses.DISCUSSION: Potential risks to SFPs with aortic insufficiency, artificial heart valves, or valvular insufficiency include lower +Gz tolerance,
earlier symptom onset, and ineffective mitigation strategies such as anti-G straining maneuvers. There are no prior studies of prolonged accelerations approximating spaceflight in such individuals. This case demonstrates tolerance of acceleration profiles in an otherwise young and healthy
individual with significant cardiac malformations, suggesting that such conditions may not necessarily preclude participation in commercial spaceflight.Blue RS, Blacher E, Castleberry TL, Vanderploeg JM. Centrifuge-simulated suborbital spaceflight in a subject with cardiac malformation. Aerosp Med Hum Perform. 2015; 86(11):999–1003.
Anderson-Doze E. You're the flight surgeon: keratoconus. Aerosp Med Hum Perform. 2015; 86(11):1004–1006.
Woodard TW. You’re the flight surgeon: Meckel’s diverticulum. Aerosp Med Hum Perform. 2015; 86(11):1006–1009.
