Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, Manitoba, Canada.
Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada.
J Neurotrauma. 2024 Apr;41(7-8):910-923. doi: 10.1089/neu.2023.0374. Epub 2023 Nov 22.
Current neurointensive care guidelines recommend intracranial pressure (ICP) and cerebral perfusion pressure (CPP) centered management for moderate-severe traumatic brain injury (TBI) because of their demonstrated associations with patient outcome. Cerebrovascular reactivity metrics, such as the pressure reactivity index (PRx), pulse amplitude index (PAx), and RAC index, have also demonstrated significant prognostic capabilities with regard to outcome. However, critical thresholds for cerebrovascular reactivity indices have only been identified in two studies conducted at the same center. In this study, we aim to determine the critical thresholds of these metrics by leveraging a unique multi-center database. The study included a total of 354 patients from the CAnadian High-Resolution TBI (CAHR-TBI) Research Collaborative. Based on 6-month Glasgow Outcome Scores, patients were dichotomized into alive versus dead and favorable versus unfavorable. Chi-square values were then computed for incrementally increasing values of each physiological parameter of interest against outcome. The values that generated the greatest chi-squares for each parameter were considered to be the thresholds with the greatest outcome discriminatory capacity. To confirm that the identified thresholds provide prognostic utility, univariate and multivariable logistical regression analyses were performed adjusting for the International Mission for Prognosis and Analysis of Clinical Trials (IMPACT) variables. Through the chi-square analysis, a lower limit CPP threshold of 60 mm Hg and ICP thresholds of 18 mm Hg and 22 mm Hg were identified for both survival and favorable outcome predictions. For the cerebrovascular reactivity metrics, different thresholds were identified for the two outcome dichotomizations. For survival prediction, thresholds of 0.35, 0.25, and 0 were identified for PRx, PAx, and RAC, respectively. For favorable outcome prediction, thresholds of 0.325, 0.20, and 0.05 were found. Univariate logistical regression analysis demonstrated that the time spent above/below thresholds were associated with outcome. Further, multivariable logistical regression analysis found that percent time above/below the identified thresholds added additional variance to the IMPACT core model for predicting both survival and favorable outcome. In this study, we were able to validate the results of the previous two works as well as to reaffirm the ICP and CPP guidelines from the Brain Trauma Foundation (BTF) and the Seattle International Severe Traumatic Brain Injury Consensus Conference (SIBICC).
目前的神经重症监护指南建议对中重度创伤性脑损伤（TBI）采用颅内压（ICP）和脑灌注压（CPP）为中心的管理方法，因为它们与患者的预后有明显的关联。脑血管反应性指标，如压力反应指数（PRx）、脉搏幅度指数（PAx）和 RAC 指数，在预后方面也表现出显著的预后能力。然而，只有在两项在同一中心进行的研究中确定了脑血管反应性指数的临界阈值。在这项研究中，我们旨在利用独特的多中心数据库来确定这些指标的临界阈值。该研究共纳入了来自加拿大高分辨率 TBI（CAHR-TBI）研究协作组的 354 名患者。根据 6 个月时的格拉斯哥预后评分，将患者分为存活与死亡以及预后良好与不良。然后针对每个感兴趣的生理参数的递增值计算卡方值，以评估其与结局的关系。对于每个参数，产生最大卡方值的数值被认为是具有最大结局区分能力的阈值。为了确认所确定的阈值具有预后实用性，我们进行了单变量和多变量逻辑回归分析，并根据国际预后和分析临床试验（IMPACT）变量进行了调整。通过卡方分析，确定了 CPP 下限为 60mmHg，ICP 为 18mmHg 和 22mmHg 作为生存和预后良好的预测阈值。对于脑血管反应性指标，对于两种结局的二分法，确定了不同的阈值。对于生存预测，PRx、PAx 和 RAC 的阈值分别为 0.35、0.25 和 0。对于预后良好的预测，阈值分别为 0.325、0.20 和 0.05。单变量逻辑回归分析表明，高于/低于阈值的时间与结局相关。此外，多变量逻辑回归分析发现，高于/低于所确定阈值的百分比时间为预测生存和预后良好的 IMPACT 核心模型增加了额外的方差。在这项研究中，我们能够验证前两项工作的结果，并再次确认了来自脑外伤基金会（BTF）和西雅图国际严重创伤性脑损伤共识会议（SIBICC）的 ICP 和 CPP 指南。
