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.
Automation reliance and functionality are ever increasing, especially in supervisory control environments like unmanned aerial vehicle (UAV) missions. Of particular relevance is understanding how automation transparency, i.e., explaining the capabilities and limitations of automation to the human in real-time, can improve human-automation performance across automated systems that vary in reliability. Two hundred seventy one Naval Aviation trainees completed a simulated multi-UAV supervisory control mission for 42 minutes with three automated systems that varied in reliability. Participants were never explicitly told the reliability varied, but halfway through the mission, they were alerted that the least reliable system may falter. Results indicated human-automation performance improved after the alert for this specific system, but not as a whole, as one system’s human-automation performance deteriorated. This work suggests uncertainty communication should not only include the specific, real-time capabilities of the automation, but also communicate unintentional consequences it may have on the whole environment.
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.
This study sought to characterize individual differences in pupillary dilations during a simple cognitive task. Eighty-four Navy and Marine Corps student pilots performed a digit memory recall test while their pupillary data were recorded. Results showed that peak pupil sizes significantly increased with difficulty of the memory task, however variability in pupillary dilations was substantial, with only 51% of individuals’ data corresponding with the aggregate results and dilations varying between participants by as much as 1 millimeter. The analyses presented in this paper illustrate the large individual variability that exists in pupil data, between individuals and even within individuals on a trial by trial basis. This work serves as a benchmark for understanding variability in pupillary dilations and encourages follow on work to explore casual mechanisms of differences in pupil dilations across individuals, especially before using pupil data for applied purposes.
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