Article

Attenuation of blast pressure behind ballistic protective vests

Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.
Injury Prevention (Impact Factor: 1.94). 04/2012; 19(1). DOI: 10.1136/injuryprev-2011-040277
Source: PubMed

ABSTRACT BACKGROUND: Clinical studies increasingly report brain injury and not pulmonary injury following blast exposures, despite the increased frequency of exposure to explosive devices. The goal of this study was to determine the effect of personal body armour use on the potential for primary blast injury and to determine the risk of brain and pulmonary injury following a blast and its impact on the clinical care of patients with a history of blast exposure. METHODS: A shock tube was used to generate blast overpressures on soft ballistic protective vests (NIJ Level-2) and hard protective vests (NIJ Level-4) while overpressure was recorded behind the vest. RESULTS: Both types of vest were found to significantly decrease pulmonary injury risk following a blast for a wide range of conditions. At the highest tested blast overpressure, the soft vest decreased the behind armour overpressure by a factor of 14.2, and the hard vest decreased behind armour overpressure by a factor of 56.8. Addition of body armour increased the 50th percentile pulmonary death tolerance of both vests to higher levels than the 50th percentile for brain injury. CONCLUSIONS: These results suggest that ballistic protective body armour vests, especially hard body armour plates, provide substantial chest protection in primary blasts and explain the increased frequency of head injuries, without the presence of pulmonary injuries, in protected subjects reporting a history of blast exposure. These results suggest increased clinical suspicion for mild to severe brain injury is warranted in persons wearing body armour exposed to a blast with or without pulmonary injury.

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    • "These emboli may then pass through the vasculature and lead to ischemic conditions in the brain (Mayorga, 1997; Wolf et al., 2009). Recent work by Wood et al. (2012) suggests that modern body armor may greatly decrease the risk of pulmonary injury due to primary blast-wave exposure, thus limiting the potential for related systemic insult. However, this method of injury remains a possibility for unarmored blast victims. "
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    ABSTRACT: This review focuses on the application of functional magnetic resonance imaging (fMRI) to the investigation of blast-related traumatic brain injury (bTBI). Relatively little is known about the exact mechanisms of neurophysiological injury and pathological and functional sequelae of bTBI. Furthermore, in mild bTBI, standard anatomical imaging techniques (MRI and computed tomography) generally fail to show focal lesions and most of the symptoms present as subjective clinical functional deficits. Therefore, an objective test of brain functionality has great potential to aid in patient diagnosis and provide a sensitive measurement to monitor disease progression and treatment. The goal of this review is to highlight the relevant body of blast-related TBI literature and present suggestions and considerations in the development of fMRI studies for the investigation of bTBI. The review begins with a summary of recent bTBI publications followed by discussions of various elements of blast-related injury. Brief reviews of some fMRI techniques that focus on mental processes commonly disrupted by bTBI, including working memory, selective attention, and emotional processing, are presented in addition to a short review of resting state fMRI. Potential strengths and weaknesses of these approaches as regards bTBI are discussed. Finally, this review presents considerations that must be made when designing fMRI studies for bTBI populations, given the heterogeneous nature of bTBI and its high rate of comorbidity with other physical and psychological injuries.
    Frontiers in Neurology 03/2013; 4:16. DOI:10.3389/fneur.2013.00016
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    • "The current form of the interceptive body armor worn by the OEF/OIF/OND deployed combat troops greatly decreases the injuries of the torso due to effective protection from shrapnel and other types of projectiles. Recent information also implies that the protective equipment the US military uses attenuate blast pressure behind the vest [24]. In spite of the widespread use of body armor, there have been a growing number of reported blast-induced lung injuries Fig. 6. "
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    • "This shift in injury location is likely due to the extensive use of personal protective equipment including ballistic protective vests (Cooper, 1996). Ballistic protective vests are known to attenuate blast overpressure seen by the thorax, therefore decreasing pulmonary injury risk below that of the head (Wood et al., 2012). "
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    ABSTRACT: Recent studies have shown an increase in the frequency of traumatic brain injuries related to blast exposure. However, the mechanisms that cause blast neurotrauma are unknown. Blast neurotrauma research using computational models has been one method to elucidate that response of the brain in blast, and to identify possible mechanical correlates of injury. However, model validation against experimental data is required to ensure that the model output is representative of in vivo biomechanical response. This study exposes porcine subjects to primary blast overpressures generated using a compressed-gas shock tube. Shock tube blasts were directed to the unprotected head of each animal while the lungs and thorax were protected using ballistic protective vests similar to those employed in theater. The test conditions ranged from 110 to 740 kPa peak incident overpressure with scaled durations from 1.3 to 6.9 ms and correspond approximately with a 50% injury risk for brain bleeding and apnea in a ferret model scaled to porcine exposure. Instrumentation was placed on the porcine head to measure bulk acceleration, pressure at the surface of the head, and pressure inside the cranial cavity. Immediately after the blast, 5 of the 20 animals tested were apneic. Three subjects recovered without intervention within 30 s and the remaining two recovered within 8 min following respiratory assistance and administration of the respiratory stimulant doxapram. Gross examination of the brain revealed no indication of bleeding. Intracranial pressures ranged from 80 to 390 kPa as a result of the blast and were notably lower than the shock tube reflected pressures of 300-2830 kPa, indicating pressure attenuation by the skull up to a factor of 8.4. Peak head accelerations were measured from 385 to 3845 G's and were well correlated with peak incident overpressure (R(2) = 0.90). One SD corridors for the surface pressure, intracranial pressure (ICP), and head acceleration are presented to provide experimental data for computer model validation.
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