Military medicine
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Assessing the survivability of, and potential injury to, a ship's crew from underwater blast is crucial to understanding the operating capability of a military vessel following blast exposure. One form of injury that can occur and affect a crew member's ability to perform tasks is traumatic brain injury (TBI). To evaluate the risk of TBI from underwater blasts, injury metrics based on linear head acceleration have traditionally been used. Although these metrics are popular given their ease of use, they do not provide a direct measure of the tissue-level biomechanical responses that have been shown to cause neuronal injury. Tissue-based metrics of injury, on the other hand, may provide more insight into the potential risk of brain injury. Therefore, in this study, we assess the risk of TBI from underwater blasts using tissue-based measures of injury, such as tissue strain, strain rate, and intracranial pressure, in addition to the more commonly used head acceleration-based injury metrics. ⋯ In this work, we assessed the risk of brain injury from underwater blasts using an anatomically detailed subject-specific FE head model. Accurate assessment of the risk of TBI from underwater explosions is important to evaluate the potential injury risk to crew members from underwater blast events, and to guide the development of future injury mitigation strategies to maintain the safety of crew members on military ships.
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The purpose of this study was to investigate the effect of environmental conditions on body composition, upper body power, and lower body power throughout a ∼4-week military mountain training exercise. We hypothesized that countermovement jump and ballistic push-up performance would decrease as a result of extended mountain field training and that winter (cold) conditions would result in greater decrements compared to fall (temperate) conditions. We also expected to observe a strong positive correlation between changes in performance and changes in skeletal muscle mass. Finally, we expected acute changes in performance upon altitude exposure. ⋯ The results of our study suggest that explosive movements are negatively affected by extended military training, seemingly independent of environmental training conditions or temperature. Planning and execution of military training should account for the likelihood that warfighter physical power will decline and may not return to pretraining levels within the month following the training event. It may also be advised to consider targeted exercises to aid in recovery of muscular strength and power. Future work should consider additional factors that likely influenced the decrease in physical performance that occurs during extended military training, such as nutrition, sleep, and psychological and cognitive stresses.
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Hypoxia presents a physiological challenge to the Warfighters during military aviation and subterranean warfare operations by decreasing the supply of oxygen to the brain, which results in a reduced cognitive function depending on the magnitude and duration of hypoxic exposure. Moderate hypoxic exposures, fractions of inspired oxygen (FiO2) of 0.11 to 0.14, show no effects on simple tasks, but complex tasks like working memory may be hindered. Unfortunately, people often cannot recognize their own symptoms of hypoxemia, which are individualistic at moderate hypoxic exposure. Thus, screening tools, like gamified cognitive assessments, during moderate hypoxia may provide personnel objective feedback to initiate safety protocols before a possible accident. However, whether gamified assessments of working memory are sensitive to moderate hypoxia is unknown. Therefore, we tested the hypothesis which moderate normobaric hypoxia decreases gamified working memory performance when accounting for the individualistic responses of arterial blood oxygen saturations. ⋯ These findings indicate that greater decreases in SpO2 during moderate hypoxic exposure hinder performance on a gamified assessment of working memory as measured by the proportion of correctly identified order and location of tiles. Considering the statistically significant decrease in both median time to first tap and median time between taps associated with the decrease in SpO2, participants are taking less time to plan or execute movements, which may compound or independently contribute to spatial and temporal memory mistakes.
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Occupational exposure to blast is a prevalent risk experienced by military personnel. While low-level exposure may not manifest immediate signs of illness, prolonged and repetitive exposure may result in neurophysiological dysfunction. Such repeated exposure to occupational blasts has been linked to structural and functional modifications in the brain, adversely affecting the performance of servicemen in the field. These neurological changes can give rise to symptoms resembling concussion and contribute to the development of post-traumatic stress disorder. ⋯ The results of our preliminary investigation offer valuable insights for further large-scale study and provide a guiding principle that necessitates a suitable mitigation approach to safeguard the health of personnel against blast overpressure.
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Stability operations, including humanitarian assistance and disaster relief missions, are key functions of U.S. Military medicine and the Military Medical Humanitarian Assistance Course (MMHAC) is a 2-day course widely used to prepare military medical personnel for such missions. It focuses on caring for those most vulnerable in the wake of disasters, particularly children. The large-scale humanitarian deployment of military medical providers in support of Operation Allies Welcome/Operation Allies Refuge (OAW/OAR) presents an opportunity to evaluate the preparedness of these providers to care for the needs of the Afghan travelers, so we explored the experiences of military medical providers deployed in support of OAW/OAR to inform improvements in the MMHAC. ⋯ Physicians found the OAR/OAW mission meaningful but also identified challenges related to medical care provision, public health, logistics, and ethical dilemmas that hindered their ability to carry out their medical mission. Lessons learned from OAW/OAR highlight several areas in which the MMHAC training could be augmented and improved to further mitigate these challenges.