An automated content-based measure of closed loop communication among critical care air transport teams.

Successful teamwork is essential to ensure critical care air transport (CCAT) patients receive effective care. Despite the importance of team performance, current training methods rely on subjective performance assessments and do not evaluate performance at the team level. Researchers have developed the Team Dynamics Measurement System (TDMS) to provide real-time, objective measures of team coordination to assist trainers in providing CCAT aircrew with feedback to improve performance. The first iteration of TDMS relied exclusively on communication flow patterns (i.e., who was speaking and when) to identify instances of various communication types such as closed loop communication (CLC). The research presented in this paper significantly advances the TDMS project by incorporating natural language processing (NLP) to identify CLC. The addition of NLP to the existing TDMS resulted in greater accuracy and fewer false alarms in identifying instances of CLC compared to the previous flow-based implementation. We discuss ways in which these improvements will facilitate instructor feedback and support further refinement of the TDMS.

Integration of a Vestibular Model for the Disorientation Research Device Motion Algorithm Application.

INTRODUCTION: Spatial disorientation (SD) remains a leading cause of Class A mishaps and fatalities in aviation. Motion-based flight simulators and other research devices provide the capacity to rigorously study SD in order to develop effective countermeasures. By applying mathematical models of human orientation perception, we propose an approach to improve control algorithms for motion-based flight simulators to study SD.METHODS: The Disorientation Research Device (DRD), or the Kraken™, is the Department of Defense's newest and most capable aerospace medicine motion-based research device. We implemented an "Observer" model for predicting aircrew spatial orientation perception within the DRD, and perceptions experienced in flight. Further, we propose a framework that uses the model output, in addition to pilot control inputs, to optimize multiaxis motion control including human-in-the-loop control capability.RESULTS: A case study was performed to demonstrate the functionality of the framework. Additionally, the case study highlights both how limitations of human perception are crucial to consider when designing motion algorithms, and the challenges of effective flight simulation with multiple motion axes.DISCUSSION: We implemented a mathematical model for spatial orientation perception to improve the design of control algorithms for motion-based flight simulators, using the DRD as an example application. We provide an example of predicting perceptions, producing quantitative information on the efficacy of motion control algorithms. This mathematical model based approach to validating motion control algorithms aims to improve the fidelity of ground-based SD research.Dixon JB, Etgan CA, Horning DS, Clark TK, Folga RV. Integration of a vestibular model for the Disorientation Research Device motion algorithm application. Aerosp Med Hum Perform. 2019; 90(10):901-907.

Preliminary Study of the Effects of Sequential Hypoxic Exposures in a Simulated Flight Task.

BACKGROUND: Previous studies of acute hypoxia have largely examined different altitudes in isolation. Pilots, however, receive two exposures during in-flight hypoxic emergencies (IFHEs): the initial exposure at altitude, followed by a second mild exposure after descending and removing the breathing mask. Conventional wisdom holds that performance recovers with blood oxygen saturation and that exposure to mild hypoxia is safe. This study examined the possibility that the effects of moderate hypoxia may linger to overlap with the effects of mild hypoxia during sequential exposures such as those experienced by pilots during an IFHE.METHODS: Subjects performed a simulated flight task and secondary task while being exposed to normobaric hypoxia via the ROBD-2.RESULTS: Average error on the flight task during exposure to 3048 m (10,000 ft) was marginally worse when preceded by exposure to 7620 m (25,000 ft; 7.40 ± 3.32) than when experienced in isolation (6.42 ± 3.82). Performance on the secondary task was likewise worse when the mild exposure followed the moderate exposure (0.27 ± 0.30 lapses per minute) than when the mild exposure occurred by itself (0.19 ± 0.20 lapses per minute). Minimum Spo2 showed a similar pattern of results (84.87 ± 4.37 vs. 86.61 ± 2.47).DISCUSSION: We believe our results are most likely due to a failure to recover from the original moderate exposure rather than an additive effect between the exposures. Even so, our findings suggest that pilot impairment following an IFHE may be worse than previously believed.Robinson FE, Horning D, Phillips JB. Preliminary study of the effects of sequential hypoxic exposures in a simulated flight task. Aerosp Med Hum Perform. 2018; 89(12):1050-1059.

Cognitive and perceptual deficits of normobaric hypoxia and the time course to performance recovery.

BACKGROUND: Many in-flight hypoxia-like incidents involve exposure to normobaric hypoxia following an oxygen delivery equipment failure. Studies have documented the effect of hypoxia on specific aspects of human performance. The goal of the present study was to establish the effects of acute hypoxia on cognitive, psychomotor, and perceptual abilities and to chronicle the time required for these capabilities to fully recover to pre-exposure levels. METHODS: Subjects were presented with a battery of tests designed to assess visual acuity, contrast sensitivity, color vision, executive control, and reaction time (simple reaction time, SRT, and choice reaction time, CRT) before, during, immediately following, 60 min, 120 min, and 24 h after hypoxic exposure. Oxygen saturation was continuously measured throughout the duration of the study using near-infrared spectroscopy measured on the forehead and finger pulse oximetry. RESULTS: During the course of six assessment periods, contrast sensitivity, color vision, and subjective workload were affected to varying degrees during hypoxic exposure, but returned to baseline levels soon after a return to normoxia. Conversely, reaction time values and regional cerebral oxygen saturation (MrSO2), while also affected during hypoxic exposure (MSRT = 362.17 ms, MCRT = 389.55 ms, MrSO2 = 79.36%), did not return to baseline levels (MSRT = 337.35 ms, MCRT = 372.75 ms, MrSO2 = 99.75%) until the assessment period 24 h following exposure (MSRT = 324.35 ms, MCRT = 366.22 ms, MrSO2 = 99.10%). DISCUSSION: Evidence from this study suggests an impairment of specific performance characteristics following hypoxic exposure - some for a considerable period of time. Mitigation efforts should focus more on the prevention of hypoxia exposure rather than relying exclusively on training operators to recognize and react earlier to hypoxic symptomology.

Forehead-mounted reflectance oximetry for in-cockpit hypoxia early detection and warning.

INTRODUCTION: Effective hypoxia-related mishap prevention relies upon aircrew rapid recognition of hypoxia symptoms. The objectives of this experiment were twofold: to compare the effectiveness of a forehead-mounted reflectance oximeter and finger-mounted pulse oximeter for application in a hypoxia early warning detection system, and to determine whether the forehead-mounted sensor could be placed within an aviation helmet. METHODS: Subjects donned an aviation flight mask and were instrumented with a forehead reflectance oximeter, a finger pulse oximeter, a blood pressure cuff, and a skin temperature sensor. Following instrumentation, subjects breathed ambient air for 10 min through the Reduced Oxygen Breathing Device (ROBD) to allow for acclimation. The baseline period was followed by one of two counterbalanced ascent profiles used to model rapid exposures to altitude. Data were collected at 1 Hz from both sensors for the duration of the protocol. RESULTS: Analyses indicated an exceptionally strong agreement between the forehead and finger sensors at all ranges of desaturation. The sensitivity data revealed that the forehead sensor was significantly faster when responding to rapid changes in SpO2 than the finger. The sensor was successfully integrated inside the helmet; however, once donned by the subject, there was considerable artifact due to pressure fluctuations. DISCUSSION: While these data may seem to suggest that the forehead sensor is accurate and sensitive to altitude induced changes in SpO2, major drawbacks exist for the technology utilized in the current study. Significant improvements aimed at diminishing noise, curbing motion artifact, and improving reliability are required to reduce errant measurements.