The purpose of this study was to investigate how concussion history affects cerebrovascular reactivity (CVR) in Special Operations Forces (SOF) combat soldiers. We studied 104 SOF soldiers [age = 33.5 ± 4.3 years; height = 179.7 ± 6.3 cm; 59 (56.7%) with self-reported concussion history]. We employed transcranial Doppler (TCD) ultrasound to measure middle cerebral artery (MCA) velocity. Baseline TCD data were collected for 2 min. Changes in MCA velocity were measured in response to five breath-holding trials and five hyperventilation trials. Cerebrovascular reactivity was quantified by the breath-holding index (BHI), vasomotor reactivity reserve (VMRr), and percent change in overall response curves. Independent t tests were employed to assess group differences in BHI, and VMRr values. We employed mixed effects models with quadratic mean structures to assess group differences in percent change MCA velocity response curves. There were no significant group differences in BHI (t102 = 0.04, p = 0.97) or VMRr (t102 = -0.33, p = 0.75). There were no group differences in relative MCA velocity response curves during the breath-holding task (F1,5092 = 0.19, p = 0.66) or during the hyperventilation task (F1,5092 = 0.41, p = 0.52) between SOF soldiers with and without a self-reported concussion history. If CVR deficits exist immediately post-concussion, our study suggests that these deficits recover over time in this population. While long-term neurophysiological effects of blast-related injury are currently unknown, assessing CVR response may provide further insight into cerebrovascular function and overall physiological health following blast exposure.

中文翻译：

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特种作战部队与士兵作战中的脑血管反应性。

这项研究的目的是调查脑震荡史如何影响特种作战部队（SOF）作战士兵的脑血管反应性（CVR）。我们研究了104名特种部队士兵[年龄= 33.5±4.3岁；高度= 179.7±6.3厘米; 自我报告的脑震荡病史为59（56.7％）。我们采用经颅多普勒（TCD）超声来测量大脑中动脉（MCA）的速度。收集2分钟的基线TCD数据。根据五次屏气试验和五次过度换气试验测量MCA速度的变化。通过屏气指数（BHI），血管舒缩反应储备（VMRr）和总反应曲线变化百分比来量化脑血管反应性。采用独立的t检验来评估BHI和VMRr值的组差异。我们使用具有二次均值结构的混合效应模型来评估MCA速度响应曲线变化百分比的组差异。BHI（t102 = 0.04，p = 0.97）或VMRr（t102 = -0.33，p = 0.75）没有明显的组别差异。有和没有SOF士兵之间的屏气任务（F1,5092 = 0.19，p = 0.66）或过度换气任务（F1,5092 = 0.41，p = 0.52）时，相对MCA速度响应曲线无组差异。自我报告的脑震荡史。如果脑震荡后立即存在CVR缺陷，我们的研究表明这些缺陷会随着时间的流逝而恢复。虽然目前尚不清楚与爆炸相关的损伤的长期神经生理影响，