Impaired cerebral compensatory reserve is associated with admission imaging characteristics of diffuse insult in traumatic brain injury

Abstract

BackgroundContinuous assessment of cerebral compensatory reserve is possible using the moving correlation between pulse amplitude of intra-cranial pressure (AMP) and intra-cranial pressure (ICP), called RAP. Little is known about the behavior and associations of this index in adult traumatic brain injury (TBI). The goal of this study is to evaluate the association between admission cerebral imaging findings and RAP over the course of the acute intensive care unit stay.MethodsWe retrospectively reviewed 358 adult TBI patients admitted to the Addenbrooke’s Hospital, University of Cambridge, from March 2005 to December 2016. Only non-craniectomy patients were studied. Using archived high frequency physiologic signals, RAP was derived and analyzed over the first 48 h and first 10 days of recording in each patient, using grand mean, percentage of time above various thresholds, and integrated area under the curve (AUC) of RAP over time. Associations between these values and admission computed tomography (CT) injury characteristics were evaluated.ResultsThe integrated AUC, based on various thresholds of RAP, was statistically associated with admission CT markers of diffuse TBI and cerebral edema. Admission CT findings of cortical gyral effacement, lateral ventricle compression, diffuse cortical subarachnoid hemorrhage (SAH), thickness of cortical SAH, presence of bilateral contusions, and subcortical diffuse axonal injury (DAI) were all associated with AUC of RAP over time. Joncheere-Terpstra testing indicated a statistically significant increase in mean RAP AUC across ordinal categories of the abovementioned associated CT findings.ConclusionsRAP is associated with cerebral CT injury patterns of diffuse injury and edema, providing some confirmation of its potential measurement of cerebral compensatory reserve in TBI.Electronic supplementary materialThe online version of this article (10.1007/s00701-018-3681-y) contains supplementary material, which is available to authorized users.

The Impact of Vasopressor and Sedative Agents on Cerebrovascular Reactivity and Compensatory Reserve in Traumatic Brain Injury: An Exploratory Analysis

“…Pressure reactivity (PRx) has emerged as a continuous measure of cerebrovascular reactivity, [4][5][6] with impaired cerebrovascular reactivity associated with poor patient outcome in TBI. [7][8][9][10][11][12] Cerebrovascular reactivity is emerging as an important component to ongoing cerebral physiological dysfunction in the setting of current guideline-based therapies. 13,14 Further, impaired cerebrovascular reactivity has been demonstrated to be associated with computed tomography (CT) based pericontusion edema progression.…”

“…15,16 In addition, novel methods using cerebrovascular reactivity physiological targets, such as optimal cerebral perfusion pressure (CPPopt) [17][18][19][20] or individual ICP (iICP) thresholds, 21,22 have emerged in personalize treatment of patients with TBI. Similarly, continuously assessed cerebral compensatory reserve using the RAP index (correlation [R] between pulse amplitude of ICP [A] and ICP [P]), 23 has been linked to CT evidence of diffuse intracranial injury 7 and 6-month global outcomes in TBI populations. 24,25 Currently, our understanding of the impact of guideline-based therapeutics, including the effects of sedatives and vasopressors, is limited to a small number of studies using aggregate data.…”

Refeeding syndrome: multimodal monitoring and clinical manifestation of an internal severe neurotrauma

“…This could be compared to a study investigating the effect of decompressive craniectomy on ICP and cerebrospinal compensation following TBI, where the median (interquartile) RAP index of 27 patients with TBI was 0.4 (0.33;0.68) prior to, and 0.14 (0.12; 0.22) after decompressive craniectomy [31]. Additionally, in a study investigating 358 patients with moderate-to-severe TBI, the mean RAP was 0.638 ± 0.208 [32]. Thus, this severely ill RFS patient seemed to have a compensatory reserve varying within the interval from normal to low throughout the entire monitoring time, without signs of complete exhaustion, and the overall trend in RAP, from day 2 to day 10, was decreasing.…”

Intracranial Pressure Monitoring Signals After Traumatic Brain Injury: A Narrative Overview and Conceptual Data Science Framework

“…In contrast, poor compensatory reserve occurs when the pulse amplitude increases alongside the mean ICP, resulting in a RAP closer to one. At the extreme end of the pressure-volume relationship, the RAP becomes −1 as there is loss of autoregulatory capacity and vessels become passive to external compression from elevated ICP (58). As useful as this may be, the RAP does have limitations based on its use of the mean ICP which may be prone to errors (as described above) and the pulse amplitude alone may be a more reliable marker of critical changes in cerebral blood volume and therefore pressure (59).…”