Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky 40536-0509, USA.
J Neurotrauma. 2011 Jan;28(1):95-104. doi: 10.1089/neu.2010.1513.
Blast-induced mild traumatic brain injury (bTBI) has become increasingly common in recent military conflicts. The mechanisms by which non-impact blast exposure results in bTBI are incompletely understood. Current small animal bTBI models predominantly utilize compressed air-driven membrane rupture as their blast wave source, while large animal models use chemical explosives. The pressure-time signature of each blast mode is unique, making it difficult to evaluate the contributions of the different components of the blast wave to bTBI when using a single blast source. We utilized a multi-mode shock tube, the McMillan blast device, capable of utilizing compressed air- and compressed helium-driven membrane rupture, and the explosives oxyhydrogen and cyclotrimethylenetrinitramine (RDX, the primary component of C-4 plastic explosives) as the driving source. At similar maximal blast overpressures, the positive pressure phase of compressed air-driven blasts was longer, and the positive impulse was greater, than those observed for shockwaves produced by other driving sources. Helium-driven shockwaves more closely resembled RDX blasts, but by displacing air created a hypoxic environment within the shock tube. Pressure-time traces from oxyhydrogen-driven shockwaves were very similar those produced by RDX, although they resulted in elevated carbon monoxide levels due to combustion of the polyethylene bag used to contain the gases within the shock tube prior to detonation. Rats exposed to compressed air-driven blasts had more pronounced vascular damage than those exposed to oxyhydrogen-driven blasts of the same peak overpressure, indicating that differences in blast wave characteristics other than peak overpressure may influence the extent of bTBI. Use of this multi-mode shock tube in small animal models will enable comparison of the extent of brain injury with the pressure-time signature produced using each blast mode, facilitating evaluation of the blast wave components contributing to bTBI.
爆炸引起的轻度创伤性脑损伤（bTBI）在最近的军事冲突中越来越常见。非撞击性爆炸暴露导致 bTBI 的机制尚未完全了解。目前，小动物 bTBI 模型主要使用压缩空气驱动的膜破裂作为其爆炸波源，而大动物模型则使用化学炸药。每种爆炸模式的压力-时间特征都是独特的，因此当使用单一爆炸源时，很难评估爆炸波的不同成分对 bTBI 的贡献。我们使用了一种多模式冲击波管，即 McMillan 爆炸装置，它可以使用压缩空气和压缩氦气驱动的膜破裂，以及作为驱动源的氧氢和环三亚甲基三硝胺（RDX，C-4 塑料炸药的主要成分）。在相似的最大爆炸超压下，压缩空气驱动爆炸的正压相持续时间更长，正冲量也大于其他驱动源产生的冲击波。氦气驱动的冲击波更类似于 RDX 爆炸，但由于取代了空气，在冲击波管内产生了缺氧环境。由氧氢驱动的冲击波的压力-时间轨迹与 RDX 产生的非常相似，尽管由于在爆炸前用于将气体包含在冲击波管内的聚乙烯袋燃烧，导致一氧化碳水平升高。暴露于压缩空气驱动爆炸的大鼠比暴露于相同峰值超压的氧氢驱动爆炸的大鼠有更明显的血管损伤，这表明除了峰值超压之外，爆炸波特征的差异可能会影响 bTBI 的程度。在小动物模型中使用这种多模式冲击波管将能够比较使用每种爆炸模式产生的脑损伤程度与压力-时间特征，从而有助于评估导致 bTBI 的爆炸波成分。
