Effects of treatment-associated variables on cerebrovascular autoregulation (CA) in acute brain injury patients remain unclear. As deficient CA is associated with worse outcomes and ideas about CA-steered management are emerging, this question is relevant. We investigated effects of norepinephrine and propofol infusion rates and hemoglobin concentration on dynamic measurements of cerebrovascular reactivity as surrogate for CA. A retrospective analysis of 91 traumatic brain injury (TBI) and 13 stroke patients admitted to the intensive care unit (ICU) of the Leuven University Hospitals was performed. Low-resolution autoregulation index (LAx) and high-frequency pressure reactivity index (PRx) were calculated as measurements of cerebrovascular reactivity. Data was binned into 5-, 15-, and 60-min intervals. Bivariate time-series analysis using lagged cross-correlations were calculated after pre-whitening and differencing. Linear mixed models evaluated effects of age, gender, cardiovascular risk, brain comorbidity, Glasgow Coma Scale (GCS), pupil reactivity, and type of injury. Median dose of norepinephrine, propofol and hemoglobin concentration was 7.8 μg/kg/h (Q1 3.6-Q3 13.8), 3 mg/kg/h (Q1 1.9-Q3 4.3), and 9.2 g·dL⁻¹ (Q1 8.2-Q3 10.5), respectively. Mean cross-correlations for 24 lags were close to zero and not significant for all variables. No significant differences as function of age, gender, cardiovascular risk, brain comorbidity, GCS, pupil reactivity, and type of injury were found. Dynamic intracranial pressure–based measurements of cerebrovascular reactivity in acute brain injured patients are not affected by gradually adjusted norepinephrine or propofol infusion rates or slow changes in hemoglobin concentration within the typical ranges during ICU admission. Future trials on cerebrovascular reactivity–steered management and treatment of CA impairment may not have to take these variables into account.

中文翻译：

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去甲肾上腺素、丙泊酚和血红蛋白浓度对急性脑损伤脑血管反应性动态测量的影响

治疗相关变量对急性脑损伤患者脑血管自动调节 (CA) 的影响仍不清楚。由于缺乏 CA 与更糟糕的结果相关，并且关于 CA 指导管理的想法正在出现，这个问题是相关的。我们研究了去甲肾上腺素和丙泊酚输注速率和血红蛋白浓度对作为 CA 替代指标的脑血管反应性动态测量的影响。对入住鲁汶大学医院重症监护室 (ICU) 的 91 名创伤性脑损伤 (TBI) 和 13 名中风患者进行了回顾性分析。计算低分辨率自动调节指数 (LAx) 和高频压力反应性指数 (PRx) 作为脑血管反应性的测量值。数据被分为 5 分钟、15 分钟和 60 分钟的间隔。在预白化和差分之后计算使用滞后互相关的双变量时间序列分析。线性混合模型评估了年龄、性别、心血管风险、脑合并症、格拉斯哥昏迷量表 (GCS)、瞳孔反应性和损伤类型的影响。去甲肾上腺素、丙泊酚和血红蛋白浓度的中位数为 7.8 μg/kg/h (Q1 3.6-Q3 13.8)、3 mg/kg/h (Q1 1.9-Q3 4.3) 和 9.2 g·dL^-1 (Q1 8.2-Q3 10.5)，分别。24 个滞后的平均互相关接近于零，并且对所有变量都不显着。未发现年龄、性别、心血管风险、脑合并症、GCS、瞳孔反应性和损伤类型的功能存在显着差异。急性脑损伤患者基于动态颅内压的脑血管反应性测量不受 ICU 入住期间逐渐调整的去甲肾上腺素或丙泊酚输注速率或典型范围内血红蛋白浓度缓慢变化的影响。未来关于脑血管反应性控制的 CA 损伤的管理和治疗试验可能不必考虑这些变量。