Risk assessment models are developed to estimate the probability of brain injury during head impact using mechanical response variables such as head kinematics and brain tissue deformation. Existing injury risk functions have been developed using different datasets based on human volunteer and scaled animal injury responses to impact. However, many of these functions have not been independently evaluated with respect to laboratory-controlled human response data. In this study, the specificity of 14 existing brain injury risk functions was assessed by evaluating their ability to correctly predict non-injurious response using previously conducted sled tests with well-instrumented human research volunteers. Six degrees-of-freedom head kinematics data were obtained for 335 sled tests involving subjects in frontal, lateral, and oblique sled conditions up to 16 Gs peak sled acceleration. A review of the medical reports associated with each individual test indicated no clinical diagnosis of mild or moderate brain injury in any of the cases evaluated. Kinematic-based head and brain injury risk probabilities were calculated directly from the kinematic data, while strain-based risks were determined through finite element model simulation of the 335 tests. Several injury risk functions substantially over predict the likelihood of concussion and diffuse axonal injury; proposed maximum principal strain-based injury risk functions predicted nearly 80 concussions and 14 cases of severe diffuse axonal injury out of the 335 non-injurious cases. This work is an important first step in assessing the efficacy of existing brain risk functions and highlights the need for more predictive injury assessment models.

Discussion focuses on the importance of aviation personnel receiving mental health treatment when problems are not severe to maximize the likelihood of returning to duty.

INTRODUCTION: The current U.S. Army aviator anthropometric screening process for rotary-wing cockpit compatibility was codified over 30 yr ago. Critical to the process are the anthropometric standards that define what is acceptable for U.S. Army flight school applicants. The purpose of this study was to assess and optimize the efficiency of the standards in screening for anthropometric cockpit compatibility while maintaining safety.METHODS: A retrospective analysis was performed. Anthropometry and disposition data of flight school applicants from 2005 to 2014 were taken from the Aeromedical Electronic Resource Office database to determine efficiency of the process. Data on mishaps from 1972 to 2017 were retrieved from the Risk Management Information System database to determine the safety benchmark of the existing process, to which adjusted standards would be held. Adjustments to standards were modeled that would more efficiently pass applicants over the period studied without exceeding the established acceptable safety level.RESULTS: There were 40,136 (98.28%) applicants who passed the standards, while 702 (1.72%) failed. Most (98.52%) applicants who failed the standards and applied for an anthropometry exception to policy (ETP) received one. The models would pass up to 396 (99.25%) applicants who received ETPs without exceeding the established number of mishaps attributable to the anthropometry standards, which was found to be zero.DISCUSSION: The screening process is efficient and effective, but could be improved. Adjusting the standards could increase process efficiency by passing more applicants during their flight physical and widening the applicant pool, while maintaining the current level of safety.Moczynski AN, Weisenbach CA, McGhee JS. Retrospective assessment of U.S. Army aviator anthropometric screening process. Aerosp Med Hum Perform. 2020; 91(9):725731.

Objective: Analysis of a high-volume military air ambulance unit and review of the U.S. Army air medical transport system and Military Assistance to Safety and Traffic (MAST) program. Setting: A remote medical system with numerous ground emergency medical services. Inclusion: All patients transported between January 1, 1996, and February 28, 1998. Exclusion: Patients who were dead on the scene or for whom records were unavailable. Methods: Retrospective review of transport and available inpatient records. Results: A total of 517 patients were transported during the study period; 461 patients met the inclusion criteria (89%). Of these, 70% were classified as trauma patients, and 30% had medical or other surgical diagnoses. Prehospital responses accounted for 71.6% of transports, and 28.4% were interhospital transfers.

The majority of injuries were at the cranio-vertebral junction, indicating that the inertial head mass caused a tensile loading mechanism to the cervical spine. These data may be used in conjunction with finite element modeling to estimate risks to the human population. The most direct application in the automotive environment could be to the well-restrained child. The N neck injury criteria, currently based on data from piglet studies, could also benefit because the NHP is a more accurate human surrogate. These types of tests are likely to never be repeated and will form an upper bound of tolerance information valuable to safety system designers.