INTRODUCTION: Earlier research described a linear relationship between the highest 1 min of oxygen consumption (Vo₂) during a recurring physical activity and incidence of decompression sickness (DCS) during research chamber exposures to high altitude. The current effort was designed to determine if that relationship holds true at a lower altitude.METHODS: Male subjects (20) were exposed without prebreathe to 22,500 ft (6858 m; 314 mmHg; 6.1 psi) for 4 h while seated, nonambulatory the entire time, with echo-imaging at 16-min intervals (Non-Amb Echo), breathing 100% oxygen. Average highest 1 min of Vo₂ and level of activity was determined. Results during Non-Amb Echo were compared with earlier research data acquired under identical conditions except for higher levels of activity.RESULTS: No DCS was reported or observed and no venous gas emboli were observed. Combined with earlier data, a strong linear relationship (r > 0.99) was observed between DCS incidence and level of activity.DISCUSSION: These results suggest physiological envelopes might be expanded or prebreathe time reduced for some high-altitude aircraft operations that involve very low levels of physical activity. They may also help to explain the higher DCS risk for inside observers vs. trainees during altitude chamber training. The data imply potential for update of altitude DCS risk prediction models by adjustment with quantified level of activity during exposure.Webb JT, Morgan TR, Sarsfield SD. Altitude decompression sickness risk and physical activity during exposure. Aerosp Med Hum Perform. 2016; 87(6):516–520.

BACKGROUND: This study was undertaken to establish a dynamic animal model of sinus barotrauma (SB).METHODS: The right nasal cavities of 65 rabbits were filled with sponges to obstruct the right ostiomeatal complex (OMC), while in the left nasal cavities, the left OMC was kept clear. The rabbits were exposed to hypobaric chamber simulation. The right sinuses were assigned as the model group, randomly divided into 13 subgroups with 5 in each subgroup, while the left sinuses were assigned as the control group. The hypobaric chamber simulation involved 6 pairs of ascending/descending speeds (100 m · s⁻¹, 75 m · s⁻¹, 50 m · s⁻¹) to 2 altitudes (13,123 ft or 6562 ft). The ascending/descending speed for Model Group 13 was 15 m · s⁻¹ to an altitude of 13,123 ft. The control group was not exposed to hypobaric chamber simulation or obstruction of the OMC. All rabbits were monitored for behavior and via nasal endoscopy, MRI, and mucosal pathology, and statistically analyzed.RESULTS: SB appeared at the ascending/descending speeds of 50 m · s⁻¹, 75 m · s⁻¹, and 100 m · s⁻¹. SB was more obvious at 100 m · s⁻¹ than at 50 m · s⁻¹ and 75 m · s⁻¹, and SB happened mainly at altitudes between 0-6562 ft. Based on behavior during hypobaric chamber simulation and the results of endoscopic morphology, imaging, and cell pathology, SB could be divided into mild, moderate, and severe.DISCUSSION: By obstructing the OMC and using hypobaric chamber simulation at high ascending/descending speeds and altitude, a dynamic rabbit model of SB at various degrees was established. The severity of SB was proportional to the ascending/descending speeds and mainly seen below 6562 ft.Xu X, Wang B, Jin Z, Zhang Y. A dynamic rabbit model of sinus barotrauma and its related pathology. Aerosp Med Hum Perform. 2016; 87(6):521–527.

INTRODUCTION: Human navigation is a very complex ability that encompasses all four stages of human information processing (sensory input, perception/cognition, selection, and execution of an action), involving both cognitive and physical requirements. During flight, the pilot uses all of these stages and one of the most critical aspect is interference. In fact, spatial tasks competing for the same cognitive resource cause greater distraction from a concurrent task than another task that uses different resource modalities.METHODS: Here we compared and contrasted the performance of pilots and nonpilots of both genders performing increasingly complex navigational memory tasks while exposed to various forms of interference. We investigated the effects of four different sources of interference: motor, spatial motor, verbal, and spatial environment, focusing on gender differences.RESULTS: We found that flight experts perform better than controls (Pilots: 6.50 ± 1.29; Nonpilots: 5.45 ± 1.41). Furthermore, in the general population, navigational working memory is compromised only by spatial environmental interference (Nonpilots: 4.52 ± 1.50); female nonpilots were less able than male nonpilots. Also, the flight expert group showed the same interference, even if reduced (Pilots: 5.24 ± 0.92); moreover, we highlighted a complete absence of gender-related effects.DISCUSSION: Spatial environmental interference is the only interference producing a decrease in performance. Nevertheless, pilots are less affected than the general population. This is probably a consequence of the need to commit substantial cognitive resources to process spatial information during flight.Verde P, Boccia M, Colangeli S, Barbetti S, Nori R, Ferlazzo F, Piccolo F, Vitalone R, Lucertini E, Piccardi L. Domain-specific interference tests on navigational working memory in military pilots. Aerosp Med Hum Perform. 2016; 87(6):528–533.

BACKGROUND: The aim of this investigation into the performance and reliability of Russian cosmonauts in hand-controlled docking of a spacecraft on a space station (experiment PILOT) was to enhance overall mission safety and crew training efficiency. The preliminary findings on the Mir space station suggested that a break in docking training of about 90 d significantly degraded performance.METHODS: Intensified experiment schedules on the International Space Station (ISS) have allowed for a monthly experiment using an on-board simulator. Therefore, instead of just three training tasks as on Mir, five training flights per session have been implemented on the ISS. This experiment was run in parallel but independently of the operational docking training the cosmonauts receive.RESULTS: First, performance was compared between the experiments on the two space stations by nonparametric testing. Performance differed significantly between space stations preflight, in flight, and postflight. Second, performance was analyzed by modeling the linear mixed effects of all variances (LME). The fixed factors space station, mission phases, training task numbers, and their interaction were analyzed. Cosmonauts were designated as a random factor. All fixed factors were found to be significant and the interaction between stations and mission phase was also significant.DISCUSSION: In summary, performance on the ISS was shown to be significantly improved, thus enhancing mission safety. Additional approaches to docking performance assessment and prognosis are presented and discussed.Johannes B, Salnitski V, Dudukin A, Shevchenko L, Bronnikov S. Performance assessment in the PILOT experiment on board space stations Mir and ISS. Aerosp Med Hum Perform. 2016; 87(6):534–544.

BACKGROUND: In 2012 the Australian Institute of Health and Welfare produced a report titled ‘Dementia in Australia.’² The report noted that the number of people with dementia in Australia would reach almost 400,000 by 2020. Australia is a jurisdiction which does not impose a mandatory retirement age for pilots. With an aging population it was hypothesized that conditions such as Parkinson’s disease (PD) were likely to be seen more commonly by the Civil Aviation Safety Authority (CASA). It was decided that this was an appropriate time to retrospectively study the data held by CASA.METHODS: An interrogation of CASA databases was undertaken. Data was produced comparing percentage of Class 1 certificate holders over 60 yr of age against time. A cohort of pilots and controllers with PD was identified. The history of the cases was reviewed.RESULTS: The study confirms that the pilot population is aging in line with population trends. Over a period from 1992 to 2012, 22 cases of pilots and controllers with PD were identified.DISCUSSION: The study confirmed that PD will be of increased relevance over the next decade. Gaps between policy and practice managing past cases were identified. Updated guidelines have been published aiming to address the deficiencies identified in the study. Historically pilots and controllers have been able to maintain certification for an average of 3.75 yr. This information should be of benefit to clinicians, pilots, and controllers when considering occupation and treatment options.Clem PA, Navathe PD, Drane MA. Identifying pilots with Parkinson’s disease. Aerosp Med Hum Perform. 2016; 87(6):545–549.

INTRODUCTION: In the United States, accident and fatality rates in helicopter emergency medical service (HEMS) operations increase significantly under nighttime environmentally hazardous operational conditions. Other studies have found pilots’ total flight hours unrelated to HEMS accident outcomes. Many factors affect pilots’ decision making, including their experience. This study seeks to investigate whether pilot domain task experience (DTE) in HEMS plays a role against likelihood of accidents at night when hazardous operational conditions are entered.METHODS: There were 32 flights with single pilot nighttime fatal HEMS accidents between 1995 and 2013 with findings of controlled flight into terrain (CFIT) and loss of control (LCTRL) due to spatial disorientation (SD) identified. The HEMS DTE of the pilots were compared with industry survey data.RESULTS: Of the pilots, 56% had ≤2 yr of HEMS experience and 9% had >10 yr of HEMS experience. There were 21 (66%) accidents that occurred in non-visual flight rules (VFR) conditions despite all flights being required to be conducted under VFR. There was a statistically significant increase in accident rates in pilots with <2 and <4 yr HEMS DTE and a statistically significant decrease in accident rates in pilots with >10 yr HEMS DTE.CONCLUSION: HEMS DTE plays a preventive role against the likelihood of a night operational accident. Pilots with limited HEMS DTE are more likely to make a poor assessment of hazardous conditions at night, and this will place HEMS flight crew at high risk in the VFR night domain.Aherne BB, Zhang C, Newman DG. Pilot domain task experience in night fatal helicopter emergency medical service accidents. Aerosp Med Hum Perform. 2016; 87(6):550–556.

INTRODUCTION: Since the debut of energy beverages, the consumption of energy beverages has been immensely popular with young adults. Research regarding energy beverage consumption has included college students, European Union residents, and U.S. Army military personnel. However, energy beverage consumption among naval aviation candidates in the United States has yet to be examined. The purpose of this study was to assess energy beverage consumption patterns (frequency and volume) among naval aviation candidates, including attitudes and perceptions regarding the benefits and safety of energy beverage consumption.METHODS: A 44-item survey was used to assess energy beverage consumption patterns of 302 students enrolled in the Aviation Preflight Indoctrination Course at Naval Air Station Pensacola, FL.RESULTS: Results indicated that 79% of participants (N = 239) reported consuming energy beverages within the last year. However, of those who reported consuming energy beverages within the last year, only 36% (N = 85) reported consuming energy beverages within the last 30 d. Additionally, 51% (N = 153) of participants reported no regular energy beverages consumption. The majority of participants consumed energy beverages for mental alertness (67%), mental endurance (37%), and physical endurance (12%). The most reported side effects among participants included increased mental alertness (67%), increased heart rate (53%), and restlessness (41%).DISCUSSION: Naval aviation candidates appear to use energy drinks as frequently as a college student population, but less frequently than expected for an active duty military population. The findings of this study indicate that naval aviation candidates rarely use energy beverages (less than once per month), but when consumed, they use it for fatigue management.Sather TE, Delorey DR. Energy beverage consumption among naval aviation candidates. Aerosp Med Hum Perform. 2016; 87(6):557–564.

BACKGROUND: Aviation exposes pilots to various occupationally related hazards, including ionizing radiation and chemical combustion. The possibility of increased prostate cancer incidence and mortality among pilots is a subject of debate. This systematic review and meta-analysis aims to summarize the supporting evidence and determine the magnitude of association.METHODS: All studies reporting prostate cancer incidence and mortality in pilots compared to the general population were included regardless of language or size. The comprehensive search included multiple databases and manual search. A random effect model was used to pool relative risks (RR) across studies.RESULTS: The final search yielded nine studies with good methodological quality. Four studies reported the incidence of prostate cancer while six reported on mortality. Pilots had a small but statistically significant increase in the risk of developing prostate cancer [RR 1.20; 95% confidence interval (CI), 1.08-1.33], but not in prostate cancer mortality (RR 1.20; 95% CI, 0.91-1.60).CONCLUSION: Pilots appear to have a very small increase in prostate cancer incidence, but not in mortality. The clinical significance of this finding is uncertain.Raslau D, Abu Dabrh AM, Summerfield DT, Wang Z, Steinkraus LW, Murad MH. Prostate cancer in pilots. Aerosp Med Hum Perform. 2016; 87(6):565–570.

INTRODUCTION: Commercial airline travel poses a recognized risk to patients with respiratory disease, including in those with asthma. Hypoxic challenge testing (HCT) is typically employed to mitigate this risk by dictating in-flight oxygen requirement.METHODS: The role of HCT has not been formally studied in patients with severe asthma and we therefore evaluated HCT assessment in a cohort of patients with severe asthma (N = 37).RESULTS: Over half (57%) of patients had a positive HCT. Baseline oxygen saturation (S_po₂) was poorly predictive of a recommendation for supplementary oxygen in flight; two-thirds of those deemed to require oxygen had a baseline S_po₂ > 95%. A combination of any two of: P_ao₂ ≤ 10.5 kPa, FEV₁ ≤ 60% predicted, and PEF ≤ 350 L · min⁻¹ predicted the need for in-flight oxygen with a sensitivity of 89% and a specificity of 69%. Furthermore, no patient with an S_po₂ > 95% and FEV₁ > 85% predicted had a positive HCT.CONCLUSION: Overall, the findings indicate that HCT should be considered for all patients with severe asthma, regardless of resting oxygen saturation level.George PM, Orton C, Ward S, Menzies-Gow A, Hull JH. Hypoxic challenge testing for fitness to fly with severe asthma. Aerosp Med Hum Perform. 2016; 87(6):571–574.

BACKGROUND: The occurrence of any intracranial bleeding is highly significant from an aeromedical risk perspective and potentially career-ending for a military aviator. Where it arises from head trauma, there is always concern regarding ongoing risk of post-traumatic epilepsy.CASE REPORT: A 26-yr-old male military aviator with persistent headache was found to have small right frontal and parietal subacute subdural hematomas, most likely precipitated by minor head trauma and possibly exacerbated by other concurrent physiological stressors. The hematomas resolved with conservative management and the aviator made a full recovery.DISCUSSION: The association between traumatic subdural hematomas and the occurrence of post-traumatic epilepsy is well documented, and this, together with the possibility of recurrent bleeding, must be considered the significant aeromedical risks. However, this case presents an unusual situation of small subdural hematomas in isolation with no other features suggestive of significant traumatic brain injury. Relevant medical literature was found to be substantially lacking, and no other similar case reports of aviators could be found. An aeromedical decision-making process is discussed in relation to returning the aviator to flying duties in a restricted capacity.Cable GG. Subdural hemorrhage in a military aviator. Aerosp Med Hum Perform. 2016; 87(6):575–579.

Cadet L, Allen A. You’re the flight surgeon: sinus barotrauma due to rapid repressurization. Aerosp Med Hum Perform. 2016; 87(6):583–585.