Workload transition rate matters: Evidence from growth curve modeling.

This research examined three specific gaps in the workload transition literature: (1) the impact of workload transition rate, (2) the applicability of current theoretical explanations, and (3) the variability of performance overall and over time. Sixty Naval flight students multitasked in an unmanned aerial vehicle control testbed and workload transitioned at three rates: slow, medium, or fast. Response time and accuracy were analyzed via growth curve modeling. Slow transitions had the largest decline in performance over time. Medium transitions had some of the slowest, but most accurate and consistent performance. Fast transitions had some of the fastest, but least accurate performance. However, all performance trends significantly varied, suggesting multiple theoretical explanations may apply and performance may also depend on the individual. Design guidance on how to maximize performance goals with transition rate is provided, but future research needs to study the theoretical explanations and impact of individual differences further.

Scan-based eye tracking measures are predictive of workload transition performance.

Given there is no unifying theory or design guidance for workload transitions, this work investigated how visual attention allocation patterns could inform both topics, by understanding if scan-based eye tracking metrics could predict workload transition performance trends in a context-relevant domain. The eye movements of sixty Naval flight students were tracked as workload transitioned at a slow, medium, and fast pace in an unmanned aerial vehicle testbed. Four scan-based metrics were significant predictors across the different growth curve models of response time and accuracy. Stationary gaze entropy (a measure of how dispersed visual attention transitions are across tasks) was predictive across all three transition rates. The other three predictive scan-based metrics captured different aspects of visual attention, including its spread, directness, and duration. The findings specify several missing details in both theory and design guidance, which is unprecedented, and serves as a basis of future workload transition research.

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.

Anemia Screening in Naval Aviation: Is Hemoglobin a Better Indicator Than Hematocrit as the Primary Index?

INTRODUCTION: Because of the rigorous mental and physical health requirements for Naval Aviation, all applicants and designated personnel must meet physical standards, including initial and periodic screening for anemia. Most standards, including for accession to the U.S. Navy, use hemoglobin as the standard marker to screen for anemia. Moreover, previous literature generally supports the assertion that hemoglobin is more reliable and accurate than hematocrit. However, the U.S. Navy Aeromedical Reference and Waiver Guide uses a hematocrit standard for anemia screening. The purpose of this study was to determine whether hemoglobin or hematocrit correlates better with clinical anemia and evaluate which index is a more accurate indicator for anemia screening in Naval Aviation personnel. MATERIALS AND METHODS: This is a retrospective cross-sectional study of Naval Aviation applicants (N = 95) who were evaluated by the Human Performance and Aeromedical Qualifications department at Naval Aerospace Medical Institute Clinic in Pensacola, Florida, from January 1, 2015 to September 30, 2018. Data were collected from electronic medical records in a de-identified manner that included demographics, class designations, labs results, diagnoses, and final disposition. Logistic regression was used to analyze whether hemoglobin (using the U.S. Navy standard of 13.5 g/dL for men and 12.0 g/dL for women) or hematocrit (using the Naval Aviation standard of 40% for men and 37% for women) predicted the diagnosis of anemia for subjects having at least one lab sample (1-sample) and for those having three samples (3-samples). Sensitivity and specificity values were calculated for hemoglobin and hematocrit as tools to predict a diagnosis of anemia using the same standards in the 1-sample and 3-sample groups. RESULTS: Data were collected for 95 subjects, 53 of whom had three sets of paired hemoglobin/hematocrit values. Using logistic regression, hemoglobin was found to be a statistically significant predictor of anemia for both the 1-sample group (odds ratio 3.4, confidence interval [1.130-10.196], P < 0.05) and the 3-sample group (odds ratio 10.5, confidence interval [1.776-62.580], P < 0.01). Hematocrit was not a significant predictor in either group. Hemoglobin was 80% sensitive and 52.3% specific for a diagnosis of anemia in the 1-sample group and 91.3% sensitive and 50.0% specific in the 3-samples group. Hematocrit was 86.7% sensitive and 35.4% specific for a diagnosis of anemia in the 1-sample group and 91.3% sensitive and 23.3% specific in the 3-samples group. CONCLUSIONS: This study found that hemoglobin correlates better with the diagnosis of anemia than hematocrit. When three samples are analyzed, hemoglobin is equally sensitive and more specific than hematocrit. Based on these results and the U.S. Navy accession standards using hemoglobin as the standard index for anemia, the U.S. Navy Aeromedical Reference and Waiver Guide should consider using hemoglobin instead of hematocrit to screen for anemia. Future research should focus on prospective research to determine whether hemoglobin or hematocrit is a better indicator of anemia in screening military personnel.

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.