Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
Department of Pediatrics, Division of Critical Care Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA.
Neurocrit Care. 2021 Feb;34(1):209-217. doi: 10.1007/s12028-020-01004-3.
Intracranial compliance refers to the relationship between a change in intracranial volume and the resultant change in intracranial pressure (ICP). Measurement of compliance is useful in managing cardiovascular and respiratory failure; however, there are no contemporary means to assess intracranial compliance. Knowledge of intracranial compliance could complement ICP and cerebral perfusion pressure (CPP) monitoring in patients with severe traumatic brain injury (TBI) and may enable a proactive approach to ICP management. In this proof-of-concept study, we aimed to capitalize on the physiologic principles of intracranial compliance and vascular reactivity to CO, and standard-of-care neurocritical care monitoring, to develop a method to assess dynamic intracranial compliance.
Continuous ICP and end-tidal CO (ETCO) data from children with severe TBI were collected after obtaining informed consent in this Institutional Review Board-approved study. An intracranial pressure-PCO Compliance Index (PCI) was derived by calculating the moment-to-moment correlation between change in ICP and change in ETCO. As such, "good" compliance may be reflected by a lack of correlation between time-synched changes in ICP in response to changes in ETCO, and "poor" compliance may be reflected by a positive correlation between changes in ICP in response to changes in ETCO.
A total of 978 h of ICP and ETCO data were collected and analyzed from eight patients with severe TBI. Demographic and clinical characteristics included patient age 7.1 ± 5.8 years (mean ± SD); 6/8 male; initial Glasgow Coma Scale score 3 [3-7] (median [IQR]); 6/8 had decompressive surgery; 7.1 ± 1.4 ICP monitor days; ICU length of stay (LOS) 16.1 ± 6.8 days; hospital LOS 25.9 ± 8.4 days; and survival 100%. The mean PCI for all patients throughout the monitoring period was 0.18 ± 0.04, where mean ICP was 13.7 ± 2.1 mmHg. In this cohort, PCI was observed to be consistently above 0.18 by 12 h after monitor placement. Percent time spent with PCI thresholds > 0.1, 0.2, and 0.3 were 62% [24], 38% [14], and 23% [15], respectively. The percentage of time spent with an ICP threshold > 20 mmHg was 5.1% [14.6].
Indirect assessment of dynamic intracranial compliance in TBI patients using standard-of-care monitoring appears feasible and suggests a prolonged period of derangement out to 5 days post-injury. Further study is ongoing to determine if the PCI-a new physiologic index, complements utility of ICP and/or CPP in guiding management of patients with severe TBI.
颅内顺应性是指颅内容积变化与颅内压（ICP）变化之间的关系。顺应性的测量在管理心血管和呼吸衰竭方面很有用；然而，目前还没有评估颅内顺应性的方法。对颅内顺应性的了解可以补充严重创伤性脑损伤（TBI）患者的 ICP 和脑灌注压（CPP）监测，并可能实现对 ICP 管理的主动方法。在这项概念验证研究中，我们旨在利用颅内顺应性和血管对 CO 的生理原理，以及标准的神经重症监护监测，开发一种评估动态颅内顺应性的方法。
在这项经过机构审查委员会批准的研究中，在获得知情同意后，从患有严重 TBI 的儿童中收集连续的 ICP 和呼气末 CO（ETCO）数据。通过计算 ICP 和 ETCO 变化之间的瞬间相关性，得出颅内压-CO 顺应性指数（PCI）。因此，“良好”的顺应性可能表现为 ICP 对 ETCO 变化的响应中缺乏相关性，而“不良”的顺应性可能表现为 ICP 对 ETCO 变化的响应中存在正相关性。
从 8 例严重 TBI 患者中收集并分析了总共 978 小时的 ICP 和 ETCO 数据。人口统计学和临床特征包括患者年龄 7.1±5.8 岁（平均值±标准差）；6/8 例为男性；初始格拉斯哥昏迷量表评分为 3 [3-7]（中位数[四分位距]）；6/8 例接受减压手术；ICP 监测天数 7.1±1.4 天；重症监护病房住院时间（LOS）16.1±6.8 天；医院 LOS 25.9±8.4 天；存活率为 100%。所有患者在整个监测期间的平均 PCI 为 0.18±0.04，平均 ICP 为 13.7±2.1mmHg。在该队列中，在放置监测器后 12 小时观察到 PCI 一直高于 0.18。PCI 阈值>0.1、0.2 和 0.3 的时间百分比分别为 62%[24]、38%[14]和 23%[15]。ICP 阈值>20mmHg 的时间百分比为 5.1%[14.6]。
使用标准的护理监测对 TBI 患者进行间接评估颅内顺应性似乎是可行的，并表明损伤后长达 5 天的时间内存在持续的紊乱。正在进行进一步的研究，以确定 PCI-一种新的生理指标是否补充 ICP 和/或 CPP 在指导严重 TBI 患者管理中的作用。
