Compensatory-Reserve-Weighted Intracranial Pressure and Its Association with Outcome After Traumatic Brain Injury

Abstract

The proposed variable shows a significant association with mortality following head injury. It is sensitive to both the rising absolute ICP and to the critical deterioration of pressure-volume compensation.

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

“…Fourth, only preliminary evidence exists to suggest the added value of RAP monitoring over ICP monitoring alone [4, 22]. This current analysis was not designed to address whether RAP provides additional value over ICP monitoring alone; it was only directed towards providing some preliminary evidence to suggest RAP is indeed a marker of intra-cranial compensatory reserve, as assessed via admission CT-based injury markers.…”

“…This current analysis was not designed to address whether RAP provides additional value over ICP monitoring alone; it was only directed towards providing some preliminary evidence to suggest RAP is indeed a marker of intra-cranial compensatory reserve, as assessed via admission CT-based injury markers. The previous work suggests that the addition of RAP monitoring to ICP, in the setting of adult TBI, does provide outcome predictive capability [4]. Though it must be acknowledged that this work is a single center retrospective analysis, much further work, using multi-variable analytic techniques, are required to determine the exact added value of RAP monitoring to ICP alone, as it pertains to patient outcome and imaging-based lesion change/progression.…”

“…More recently, the moving correlation coefficient between slow-waves of pulse amplitude of ICP (AMP) and ICP, called RAP (R, correlation; A, AMP; P, ICP), has been previously proposed as a surrogate measure of compensatory reserve [4, 15]. The majority of the clinical literature to date focuses on the application of this particular index in monitoring hydrocephalus patients and assessing compensatory reserve during cerebrospinal fluid (CSF) infusion studies [7, 15].…”

“…The majority of the clinical literature to date focuses on the application of this particular index in monitoring hydrocephalus patients and assessing compensatory reserve during cerebrospinal fluid (CSF) infusion studies [7, 15]. Though a recent study evaluated compensatory reserve weighted ICP measurements, where weighted ICP = ICP × (1-RAP), which demonstrated that weighted ICP measures was associated with mortality in adult TBI [4]. …”

Brain pulsations enlightened

“…RAP = 0 indicates good compensatory reserve (the linear part of the P-V curve at low ICP), whereas RAP close to + 1 shows poor compensatory reserve (the exponential part of the P-V curve) [17]. & Negative RAP at ICP > 25 mmHg indicates the critical closing of cerebral arterioles due to intracranial hypertension [12]. & The correlation coefficient between slow waves of arterial blood pressure and the pulse amplitude of ICP (the socalled PAx index) provides information about the autoregulation of CBF, and is an alternative to PRx, the pressurereactivity index [4].…”