Division of Anesthesia, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom.
Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.
J Neurotrauma. 2020 Jun 1;37(11):1306-1314. doi: 10.1089/neu.2019.6726. Epub 2020 Feb 25.
Decompressive craniectomy (DC) in traumatic brain injury (TBI) has been suggested to influence cerebrovascular reactivity. We aimed to determine if the statistical properties of vascular reactivity metrics and slow-wave relationships were impacted after DC, as such information would allow us to comment on whether vascular reactivity monitoring remains reliable after craniectomy. Using the CENTER-TBI High Resolution Intensive Care Unit (ICU) Sub-Study cohort, we selected those secondary DC patients with high-frequency physiological data for both at least 24 h pre-DC, and more than 48 h post-DC. Data for all physiology measures were separated into the 24 h pre-DC, the first 48 h post-DC, and beyond 48 h post-DC. We produced slow-wave data sheets for intracranial pressure (ICP) and mean arterial pressure (MAP) per patient. We also derived a Pressure Reactivity Index (PRx) as a continuous cerebrovascular reactivity metric updated every minute. The time-series behavior of the PRx was modeled for each time period per patient. Finally, the relationship between ICP and MAP during these three time periods was assessed using time-series vector autoregressive integrative moving average (VARIMA) models, impulse response function (IRF) plots, and Granger causality testing. Ten patients were included in this study. Mean PRx and proportion of time above PRx thresholds were not affected by craniectomy. Similarly, PRx time-series structure was not affected by DC, when assessed in each individual patient. This was confirmed with Granger causality testing, and VARIMA IRF plotting for the MAP/ICP slow-wave relationship. PRx metrics and statistical time-series behavior appear not to be substantially influenced by DC. Similarly, there is little change in the relationship between slow waves of ICP and MAP before and after DC. This may suggest that cerebrovascular reactivity monitoring in the setting of DC may still provide valuable information regarding autoregulation.
去骨瓣减压术（DC）在创伤性脑损伤（TBI）中被认为会影响脑血管反应性。我们旨在确定血管反应性指标和慢波关系的统计特性是否在 DC 后受到影响，因为此类信息将使我们能够对血管反应性监测在去骨瓣后是否仍然可靠发表评论。我们使用 CENTER-TBI 高分辨率重症监护病房（ICU）子研究队列，选择了那些在至少 24 小时前 DC 之前和 48 小时后 DC 之后具有高频生理数据的继发性 DC 患者。所有生理学测量的数据均分为 24 小时前 DC、DC 后 48 小时内和 48 小时后。我们为每位患者的颅内压（ICP）和平均动脉压（MAP）制作了慢波数据表。我们还推导出了一个压力反应性指数（PRx）作为连续的脑血管反应性指标，每分钟更新一次。为每位患者的每个时间段建立了 PRx 的时间序列行为模型。最后，使用时间序列向量自回归综合移动平均（VARIMA）模型、脉冲响应函数（IRF）图和格兰杰因果关系检验评估这三个时间段内 ICP 和 MAP 之间的关系。这项研究纳入了 10 名患者。PRx 的平均值和超过 PRx 阈值的时间比例不受去骨瓣的影响。同样，当在每个个体患者中评估时，PRx 时间序列结构不受 DC 的影响。这通过格兰杰因果关系检验和 MAP/ICP 慢波关系的 VARIMA IRF 图得到了证实。PRx 指标和统计时间序列行为似乎没有受到 DC 的显著影响。同样，在 DC 前后，ICP 和 MAP 的慢波之间的关系变化很小。这可能表明在 DC 情况下的脑血管反应性监测仍可能提供有关自动调节的有价值的信息。
