Compensatory-reserve-weighted intracranial pressure versus intracranial pressure for outcome association in adult traumatic brain injury: a CENTER-TBI validation study

Abstract

Background Compensatory-reserve-weighted intracranial pressure (wICP) has recently been suggested as a supplementary measure of intracranial pressure (ICP) in adult traumatic brain injury (TBI), with a single-center study suggesting an association with mortality at 6 months. No multi-center studies exist to validate this relationship. The goal was to compare wICP to ICP for association with outcome in a multi-center TBI cohort. Methods Using the Collaborative European Neuro Trauma Effectiveness Research in TBI (CENTER-TBI) high-resolution intensive care unit (ICU) cohort, we derived ICP and wICP (calculated as wICP = (1 − RAP) × ICP; where RAP is the compensatory reserve index derived from the moving correlation between pulse amplitude of ICP and ICP). Various univariate logistic regression models were created comparing ICP and wICP to dichotomized outcome at 6 to 12 months, based on Glasgow Outcome Score—Extended (GOSE) (alive/dead—GOSE ≥ 2/GOSE = 1; favorable/unfavorable—GOSE 5 to 8/GOSE 1 to 4, respectively). Models were compared using area under the receiver operating curves (AUC) and p values. Results wICP displayed higher AUC compared to ICP on univariate regression for alive/dead outcome compared to mean ICP (AUC 0.712, 95% CI 0.615–0.810, p = 0.0002, and AUC 0.642, 95% CI 0.538–746, p < 0.0001, respectively; no significant difference on Delong’s test), and for favorable/unfavorable outcome (AUC 0.627, 95% CI 0.548–0.705, p = 0.015, and AUC 0.495, 95% CI 0.413–0.577, p = 0.059; significantly different using Delong’s test p = 0.002), with lower wICP values associated with improved outcomes ( p < 0.05 for both). These relationships on univariate analysis held true even when comparing the wICP models with those containing both ICP and RAP integrated area under the curve over time ( p < 0.05 for all via Delong’s test). Conclusions Compensatory-reserve-weighted ICP displays superior outcome association for both alive/dead and favorable/unfavorable dichotomized outcomes in adult TBI, through univariate analysis. Lower wICP is associated with better global outcomes. The results of this study provide multi-center validation of those seen in a previous single-center study. Electronic supplementary material The online version of this article (10.1007/s00701-019-03915-3) contains supplementary material, which is available to authorized users.

Descriptive analysis of low versus elevated intracranial pressure on cerebral physiology in adult traumatic brain injury: a CENTER-TBI exploratory study

“… Area under RAP over time: Given complexities with interpreting RAP, we determined the area under the RAP over time curve for the RAP thresholds of 0 and + 0.4 (RAP AUC 0, and RAP AUC + 0.4), using a linear interpolation method of integration. Such methodology has been described previously by our group [ 34 , 35 ]. …”

“…Data from such preliminary work supports the association between persistently elevated ICP and mortality at 6 months post-TBI. [ 6 , 14 , 24 ] Similarly, persistent ICP elevations have been shown to be potentially linked to lower CPP values, [ 6 ] worse compensatory reserve, [ 5 , 34 ] impaired cerebrovascular reactivity, [ 1 , 10 , 14 ] lower PbtO 2 values, [ 16 , 22 ] and autonomic dysfunction, [ 15 , 26 ] in those rare data sets with high-frequency digital physiology. However, most studies have suffered from several limitations.…”

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

“…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. 10,13,26,27 A recent 25year retrospective analysis by Donnelly and associates suggested that, despite changes in TBI management guidelines over various epochs, cerebrovascular reactivity remained essentially unchanged, with mortality rates in patients with moderate/severe TBI being relatively fixed.…”

The impact of hypertonic saline on cerebrovascular reactivity and compensatory reserve in traumatic brain injury: an exploratory analysis

“…Similarly, continuously assessed cerebral compensatory reserve, using the RAP (correlation (R) between pulse amplitude of ICP (A) and ICP (P)), has emerged as a potential surrogate metric for compliance [ 11 , 31 , 49 , 50 ]. Recent data suggests association of high area under the RAP vs. time curve, with admission CT characteristics of diffuse intracranial injury, as well as poor global outcome at 6 months post-TBI [ 50 ].…”