INTRODUCTION Adequate cerebral perfusion prevents secondary insult after traumatic brain injury (TBI). Cerebral autoregulation (CAR) keeps cerebral blood flow (CBF) constant when arterial blood pressure (ABP) changes. Aim of the study was to evaluate the existence of delayed CAR in TBI patients and its possible association with outcome. METHODS We retrospectively analysed TBI patients. Flow velocity (FV) in middle cerebral artery, invasive intra-cranial pressure (ICP) and ABP were recorded. Cerebral perfusion pressure (CPP) was calculated as ABP - ICP. Mean flow index (Mx) > 0.3 defined altered CAR. Samples from patients with altered CAR were further analysed: FV signal was shifted backward relative to CPP; Mx was calculated after each shift (MxD). Mx > 0.3 plus MxD ≤ 0.3 defined delayed CAR. Favourable outcome (FO) at 6 months was defined as Glasgow Outcome Scale 4-5. RESULTS 154 patients were included. GCS was 6 [4-9], ICP was 14 [9-20] mmHg. Data on 6 months outcome were available for 131 patients: 104/131 patients (79 %) were alive; GOS was 4 [3-5]; 70/131 (53 %) had FO. Mx was 0.07 [-0.19 to 0.28] overall. Mx was lower in patients with FO compared others (0.00 [-0.21 to 0.20] vs 0.17 [-0.12 to 0.37], p = 0.02). 118 (77 %) patients had intact CAR and 36 (23 %) patients had altered CAR; 23 patients - 15 % of the general cohort and 64 % of patients with altered CAR - had delayed CAR. Delay in the autoregulatory response was 2 [1-4] seconds. 80/98 (82 %) of patients with intact CAR survived, compared to 16/21 (76 %) with delayed and 8/12 (67 %) with altered CAR (p = 0.20). 80/98 (58 %) patients with intact, 10/21 (48 %) patients with delayed and 3/12 (25 %) patients with altered CAR had FO (p = 0.03). CONCLUSION A subgroup of TBI patients with delayed CAR was identified. Delayed CAR was associated with better neurological outcome than altered CAR.

中文翻译：

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颅脑外伤患者大脑自动调节延迟

引言 充足的脑灌注可防止外伤性脑损伤 (TBI) 后的继发性损伤。当动脉血压 (ABP) 发生变化时，大脑自动调节 (CAR) 可保持脑血流量 (CBF) 恒定。该研究的目的是评估 TBI 患者中延迟 CAR 的存在及其与结果的可能关联。方法 我们回顾性分析了 TBI 患者。记录大脑中动脉的流速（FV）、侵入性颅内压（ICP）和 ABP。脑灌注压 (CPP) 计算为 ABP - ICP。平均流量指数 (Mx) > 0.3 定义了改变的 CAR。对 CAR 改变的患者样本进行了进一步分析：FV 信号相对于 CPP 向后移动；Mx 在每次班次 (MxD) 后计算。Mx > 0.3 加上 MxD ≤ 0.3 定义的延迟 CAR。6 个月时的良好结果 (FO) 被定义为格拉斯哥结果量表 4-5。结果 包括 154 名患者。GCS 为 6 [4-9]，ICP 为 14 [9-20] mmHg。可获得 131 名患者的 6 个月结果数据：104/131 名患者 (79 %) 存活；GOS 为 4 [3-5]；70/131 (53 %) 有 FO。Mx 总体为 0.07 [-0.19 至 0.28]。与其他人相比，FO 患者的 Mx 较低（0.00 [-0.21 至 0.20] vs 0.17 [-0.12 至 0.37]，p = 0.02）。118 名 (77 %) 患者具有完整的 CAR，36 名 (23 %) 患者具有改变的 CAR；23 名患者——15% 的普通队列和 64% 的 CAR 改变的患者——延迟了 CAR。自动调节反应的延迟为 2 [1-4] 秒。80/98 (82 %) 的完整 CAR 患者存活，而延迟的 16/21 (76 %) 和 8/12 (67 %) 的 CAR (p = 0.20)。80/98 (58 %) 患者完好，10/21 (48 %) 延迟患者和 3/12 (25 %) CAR 改变患者有 FO (p = 0.03)。结论 确定了延迟 CAR 的 TBI 患者亚组。与改变的 CAR 相比，延迟的 CAR 与更好的神经学结果相关。