Upper Limits of Cerebral Perfusion Pressure in Pediatric Traumatic Brain Injury – A STARSHIP Analysis

Background/Objective Low cerebral perfusion pressure (CPP) has previously been identified as a key prognostic marker after pediatric traumatic brain injury (TBI). Cerebrovascular autoregulation supports stabilization of cerebral blood flow within the autoregulation range. Beyond the upper limit of this range, cerebral blood flow increases with increasing CPP leading to increased risk of intracranial hypertension and blood-brain-barrier disruptions. In contrast to lower CPP limits, little research has explored the effects of high CPP on outcome. Based on the hypothesis that children are less sensitive to high CPP, we aimed to characterize the pediatric upper limit of autoregulation and its association to outcome. Methods Data acquired as part of STARSHIP (a prospective, multicenter, observational study which enrolled 135 children with TBI from July 2018 to March 2023) was explored. The association between different levels of CPP and the autoregulation proxy measure PRx (the pressure reactivity index) were explored visually. The prognostic value of CPP was assessed by exploring overall averages, overall dose, hourly dose, and percentage time spent above specific thresholds. We employed both uni/multivariable (Chi2 tests, logistic regression, sliding dichotomy), and visual (heatmap) methods. Results In contrast to the clearly identifiable lower limit, no clear upper limit of autoregulation could be identified with PRx increasing beyond 0.2 only with CPP values beyond 100 mmHg. Using iterative Chi2 testing and logistic regression analyses, similarly, only hourly dose and percentage time beyond CPP of 90 mmHg displayed a trend towards worse outcome. Using heatmap analyses, safe regions of CPP could be identified. No difference in CPP could be identified between patients with and without acute respiratory distress syndrome or secondary hemorrhages. Conclusions Considering the undisputed association between low CPP and outcome, our results support targeting higher CPP values which does not appear to worsen outcome after pediatric TBI.