Human Papilloma Virus Vaccination Compliance in a Military Aviation Training Community.

INTRODUCTION: Human Papilloma Virus (HPV) vaccination compliance as reported by the CDC in 2011 falls short of a national goal to have 80% of adolescents vaccine-complete by 2020. The Naval Aviation Schools Command, Pensacola, Florida offers a single point of contact for military aviation trainees offering near-complete capture of an HPV vaccine target population. The purpose of this study is to identify baseline HPV vaccination rates among military aviation trainees and whether or not the provision of educational materials at the start of aviation training would increase future HPV vaccination compliance. MATERIALS AND METHODS: Approval to conduct this study was obtained from the Institutional Review Board of Naval Medical Center Portsmouth, Virginia. Our population of interest consisted of US Navy and Marine Corps student naval aviators, student naval flight officers (officers), and student enlisted air crew (enlisted) reporting for aviation related duty. A convenience sampling of officer and enlisted student classes checking in for training was performed over a period of 6 months. The first 3 months of students were assigned as the intervention group and the remaining 3 months of students were assigned to the control group. This study was conducted in two parts: (1) an anonymous survey captured cross-sectional data of self-reported HPV vaccine use, and (2) prospective analysis of service members' HPV vaccine rates before and after educational intervention as documented within the military's electronic health record system, Armed Forces Health Longitudinal Technology Application (AHLTA). RESULTS: AHLTA immunization status was evaluated for 1,164 personnel; 114 (9.8%) were excluded for missing basic vaccination information. Of the remaining 1,050, another 199 (19%) members were excluded as already vaccine complete (evidenced by three shots documented) prior to entry into the study. Within the 199 service members with documented baseline HPV vaccination completion, 197/199 (99%) were officers and 2/199 (0.1%) were enlisted. A total of 851 personnel were included for prospective analysis. Person-time of 100 person years was used and the vaccination rate translates to 16.62/100 person years (95% CI 11.29, 23.59) within intervention vs. 2.96/100 person years (95% CI 0.80, 7.58) within control groups and are significantly different (P = 0.0001). Comparing intervention and control groups, rate ratios = 5.61 (95% CI 2.14, 18.64) and rate differences = 13.66 (95% CI 7.13, 20.19). Among intervention group survey responders who previously reported nonvaccine use, 50.5% reported a change in opinion about obtaining the vaccination, with a higher proportion of enlisted members reporting a change in opinion (62.8% vs. 39.7%, P = 0.0053). CONCLUSIONS: Electronic health records immunizations review noted a baseline vaccine completion rate of 19%. Our study showed a health inequity between enlisted and officers, with officers having 99% of the documented baseline completion rates per AHLTA data. Our prospective analysis noted statistically significant rate differences of 13.66% and rate ratios of 5.61 between intervention and control groups. This analysis of AHLTA data combined with survey response of 50.5% indicating a change in opinion about HPV vaccine use among those who had not yet started vaccine series suggests targeted education would be a low-cost intervention to improve HPV vaccine use rates.

Gender Differences in Dry-EEG Manifestations During Acute and Insidious Normobaric Hypoxia.

INTRODUCTION: Prior research suggests there may be gender differences with regards to hypoxia resilience. Our study was designed to determine whether there were differences between genders in neuronal electrical activity at simulated altitude and whether those changes correlated with cognitive and aviation performance decrements.METHODS: There were 60 student Naval Aviators or Flight Officers who completed this study (30 women, 30 men). Participants were exposed to increasing levels of normobaric hypoxia and monitored with dry EEG while flying a fixed-base flight simulation. Gender differences in brainwave frequency power were quantified using MATLAB. Changes in flight and cognitive performance were analyzed via simulation tasks and with a cognitive test validated under hypoxia.RESULTS: Significant decreases in theta and gamma frequency power occurred for women compared to men with insidious hypoxic exposures to 20K, with an average frequency power decrease for women of 19.4% compared to 9.3% for men in theta, and a 42.2% decrease in gamma for women compared to 21.7% for men. Beta frequency power correlated highest between genders, with an average correlation coefficient of r = 0.95 across seven channels.DISCUSSION: Results of this study suggest there is identifiable brain wave suppression for both men and women with hypoxic exposure and, moreover, there are significant differences in this suppression between genders. Beta frequency power was most sensitive for both genders and highly correlative compared to other brainwave frequencies. The implications of these findings are important considerations for next-generation aviation helmets, which may employ this technology as an early warning mechanism.Rice GM, Snider D, Drollinger S, Greil C, Bogni F, Phillips J, Raj A, Marco K, Linnville S. Gender differences in dry-EEG manifestations during acute and insidious normobaric hypoxia. Aerosp Med Hum Perform. 2019; 90(4):369-377.

Dry-EEG Manifestations of Acute and Insidious Hypoxia During Simulated Flight.

INTRODUCTION: Recently, portable dry electroencephalographs (dry-EEGs) have indexed cognitive workload, fatigue, and drowsiness in operational environments. Using this technology this project assessed whether significant changes in brainwave frequency power occurred in response to hypoxic exposures as experienced in military aviation.METHODS: There were 60 (30 women, 30 men) student Naval Aviators or Flight Officers who were exposed to an intense (acute) high-altitude (25,000 ft) normobaric hypoxic exposure, and 20 min later, more gradual (insidious) normobaric hypoxic exposure up to 20,000 ft while flying a fixed-wing flight simulation and monitored with a dry-EEG system. Using MATLAB, EEG frequencies and power were quantified and analyzed. Cognitive performance was also assessed with a cognitive task validated under hypoxia. Normobaric hypoxia and O2 saturation (Spo2) were produced and monitored using the Reduced Oxygen Breathing Device (ROBD2).RESULTS: Significant Spo2 decreases were recorded at acute 25K and insidious 20K simulated altitudes. Significant power decreases were recorded in all frequencies (alpha, beta, gamma, and theta) and all channels with acute 25K exposures. Gamma, beta, and theta frequency power were significantly decreased with insidious 20K exposures at most of the channels. The frequency power decreases corresponded to significant decreases in cognitive performance and flight performance. Most importantly, frequency power suppressions occurred despite 42% of the volunteers not perceiving they were hypoxic in the acute phase, nor 20% in the insidious phase.DISCUSSION: Results suggest EEG suppression during acute/insidious hypoxia can index performance decrements. These findings have promising implications in the development of biosensors that mitigate potential in-flight hypoxic physiological episodes.Rice GM, Snider D, Drollinger S, Greil C, Bogni F, Phillips J, Raj A, Marco K, Linnville S. Dry-EEG manifestations of acute and insidious hypoxia during simulated flight. Aerosp Med Hum Perform. 2019; 90(2):92-100.

Wearable Accelerometers in High Performance Jet Aircraft.

INTRODUCTION: Wearable accelerometers have become ubiquitous in the fields of exercise physiology and ambulatory hospital settings. However, these devices have yet to be validated in extreme operational environments. The objective of this study was to correlate the gravitational forces (G forces) detected by wearable accelerometers with the G forces detected by high performance aircraft. METHODS: We compared the in-flight G forces detected by the two commercially available portable accelerometers to the F/A-18 Carrier Aircraft Inertial Navigation System (CAINS-2) during 20 flights performed by the Navy's Flight Demonstration Squadron (Blue Angels). Postflight questionnaires were also used to assess the perception of distractibility during flight. RESULTS: Of the 20 flights analyzed, 10 complete in-flight comparisons were made, accounting for 25,700 s of correlation between the CAINS-2 and the two tested accelerometers. Both accelerometers had strong correlations with that of the F/A-18 Gz axis, averaging r = 0.92 and r = 0.93, respectively, over 10 flights. Comparison of both portable accelerometer's average vector magnitude to each other yielded an average correlation of r = 0.93. Both accelerometers were found to be minimally distracting. DISCUSSION: These results suggest the use of wearable accelerometers is a valid means of detecting G forces during high performance aircraft flight. Future studies using this surrogate method of detecting accelerative forces combined with physiological information may yield valuable in-flight normative data that heretofore has been technically difficult to obtain and hence holds the promise of opening the door for a new golden age of aeromedical research.

Evidence for -Gz Adaptation Observed with Wearable Biosensors During High Performance Jet Flight.

INTRODUCTION: Few studies have evaluated physiological responses to high acceleration forces during actual flight and to our knowledge no normative data has been acquired by technologies such as wearable biosensors during high performance jet aircraft operations. METHODS: In-flight physiological data from an FDA cleared portable triaxial accelerometer and bio-sensor were observed from five active duty F-18 pilots of the Naval Flight Demonstration Squadron (Blue Angels). Of the five pilots, three were formation pilots who flew lower G profiles and two were solo pilots who flew higher G profiles. Physiological parameters monitored were heart rate, respiratory rate, temperature, caloric expenditure, and duration of exposure to levels of acceleration. RESULTS: Evaluated were 25 practice demonstration flights; 9 flights were excluded secondary to incomplete or inaccurate physiological data. We observed no significant bradycardia during a total of 189 maneuvers which met inclusion criteria for push-pull events (PPE) or isolated -Gz exposures. Further analysis of 73 PPE revealed an overall significant rise in HR following the PPE, where mean heart rate was 106 (95% CI, 100:112) at the beginning of the push and 129 (95% CI, 123:135) following the pull. DISCUSSION: A majority of the flights monitored provided reliable physiological data. Initial data suggests, contrary to currently held aeromedical doctrine, maneuvers such as the "push-pull" do not evoke vasovagal based bradycardic responses in aerobatic pilots. Possible explanations for these findings are sympathetic nervous system activation through adaptation and/or sustained isometric resistance from control inputs, both of which are areas of future research for our team.Rice GM, Snider D, Moore JL, Lavan JT, Folga R, VanBrunt TB. Evidence for -Gz adaptation observed with wearable biosensors during high performance jet flight. Aerosp Med Hum Perform. 2016; 87(12):996-1003.

Urinary tract calculi in military aviators.

BACKGROUND: Urinary tract calculi are a common affliction in the United States and estimates of the adult lifetime risk of developing this condition range from 10 to 15%. Although highly variable, the clinical presentation of someone afflicted with urinary tract calculi typically involves varying degrees of pain, nausea, hematuria, and dysuria. Current disease, as well as a history of urinary tract calculi, is potentially disqualifying for aviation duties in the United States military as well as for commercial aviators. METHODS: Utilizing population based data from the Defense Medical Epidemiology Database (DMED), the current descriptive epidemiology of urinary tract calculi among military aviators was examined. RESULTS: Based on the data collected, the overall annual incidence density of urinary tract calculi for DoD personnel is approximately 4.8 events/1000 PY. The overall annual incidence density of urinary tract calculi is slightly lower in aviators as compared to the nonaviator DoD population (4.4 events/1000 PY vs. 4.8 events/1000 PY). DISCUSSION: Even though in-flight incapacitation from this malady is believed to be exceedingly rare, the incidence of urinary tract stones and their related morbidity should remain an important area of clinical focus.

Type II decompression sickness in naval hypobaric chambers: A case of mistaken identity?

INTRODUCTION: Historically, U.S. Navy clinicians have used the U.S. Navy Dive Manual for guidance in the diagnosis and treatment of injuries incurred during hyper- or hypobaric operations. Based on this manual, paresthesias are considered to be central nervous system manifestations and thus are classified as Type II (severe) decompression sickness (DCS). Yet given the highly successful response to treatment of peripheral nervous system manifestations of DCS in the literature, both the diving and aviation communities have questioned its classification as "severe" DCS. This record review was undertaken to examine U.S. Naval severe cases of altitude DCS with the goal of identifying dissimilarities between hypobaric facilities in classification and incidence. METHODS: Hypobaric exposures and cases were reviewed from quarterly training reports maintained at the Naval Operational Medicine Institute, Pensacola, FL, between January 1993 and April 2004. Cases were analyzed for age, gender, flight profile, symptom complex, type of DCS, and treatment provided. RESULTS: There were 50,355 hypobaric exposures resulting in 97 cases of altitude DCS. Of the 97 cases of diagnosed DCS, 58 were classified as Type II, while 39 were Type I. Of the 58 cases of Type II DCS, 29 were diagnosed as Type II by the sole finding of non-dermatomal paresthesias. DISCUSSION: Type II DCS, a designation traditionally reserved for severe DCS, is frequently diagnosed by the sole finding of non-dermatomal paresthesias in Naval hypobaric training. A review and revision of the U.S. Naval Aviation classification system for altitude DCS should be undertaken with emphasis on severity not symptomatology.

Incidence of decompression sickness in hypoxia training with and without 30-min O2 prebreathe.

BACKGROUND: All naval aviators, navigators, and aircrewmen are required to participate in hypoxia familiarization training. This training is performed in a hypobaric chamber and is considered high risk due to the potential for barotrauma and/or decompression sickness (DCS). Prior analysis of the DCS in U.S. Navy hypobaric chambers revealed a significantly higher incidence among inside observers (IOs) compared with students. In response to these reports, all IOs are required to denitrogenate by breathing 100% oxygen for 30 min prior to altitude exposure (prebreathing). Although the Army, Navy, and Air Force prebreathe for 30 min prior to most hypobaric training exposures, there have been no reports validating the efficacy of this measure. This study examined the incidence of altitude DCS during training exposures to simulated altitudes of 25,000 ft (25k) and 35,000 ft (35k) in IOs and students, some of whom prebreathed and some of whom did not. METHODS: Exposures and DCS cases for a period of 9 yr were tabulated from training reports maintained at the Naval Operational Medicine Institute in Pensacola, FL. Chi-square or Fisher's Exact test was used to compare the data sets and p < or = 0.05 was considered significant. RESULTS: The overall DCS incidence for students and IOs for all chamber profiles was 0.25%. The incidence for 25k was 0.29% for students who did not prebreathe and 0.15% for IOs who did (p = 0.10). Within the student group there was a 0.44% DCS incidence for 25k with no prebreathe and a 0.17% DCS incidence for 35k with prebreathe (p = 0.004). CONCLUSIONS: A 30-min prebreathe prior to altitude exposure appears to contribute to a reduction in the risk of DCS during hypobaric chamber training.