Autoregulation-guided intracranial pressure and cerebral perfusion pressure targets in different subtypes and characteristics of traumatic brain injury.

backgroundConsidering the significant heterogeneity of traumatic brain injury (TBI), uniform treatment thresholds applied to all patients may be overly simplistic. Cerebral autoregulation (CA) capacity may vary significantly between TBI patients and may change dynamically over time. Within a precision neurointensive care framework, this study aimed to evaluated the associations between cerebral perfusion pressure (CPP) or intracranial pressure (ICP) and the pressure reactivity index (PRx) in patients with different types of TBI, and to investigated whether PRx modified the associations between ICP and CPP and functional outcome.

methodsA prospective observational study was performed. Eligible patients had acute TBI with ICP, and arterial blood pressure monitoring and available 6-month outcome data assessed using the Glasgow Outcome Scale–Extended (GOSE). During the first 7 days postinjury, we calculated the proportion of good monitoring time (%GMT) spent predefined thresholds. The %GMT within predefined cerebral physiological intervals of PRx in combination with ICP or CPP, in relation to outcome, was analyzed using two-variable heatmaps. The associations between PRx and ICP or CPP were further evaluated using generalized additive models (GAMs) with cubic splines.

resultsIn total, 187 patients requiring invasive neuromonitoring after TBI were included. PRx exhibited a U-shaped relationship with CPP, with the optimal PRx observed at a CPP of 70–80 mmHg. In the PRx–ICP heatmap, the combination of elevated PRx and high ICP was significantly associated with worse outcomes. In the PRx–CPP heatmap, outcomes worsened when CPP decreased and PRx deviated from 0. Lower CPP appeared better tolerated in patients with preserved autoregulation, as indicated by lower PRx values. Patients without decompressive craniectomy (DC), with diffuse injury or younger age demonstrated better tolerance to lower CPP when autoregulatory function was preserved compared to patients with DC, focal injury or older age. When all physiological variables were incorporated into a single multivariable model, only composite variable 2 remained independently associated with favorable outcome (odds ratio [OR] 1.026, 95% confidence interval [CI] 1.006–1.046, P = 0.012).

conclusionsThis study provides novel insights into cerebral physiology across various TBI subtypes by delineating safe and hazardous thresholds for ICP, PRx, and CPP. The acceptable lower limit of CPP appears to be directly proportional to the PRx. Consequently, patients with severe impairment of CA may require higher CPP targets to achieve favorable outcomes. These findings emphasize the importance of individualizing target CPP based on PRx dynamics rather than relying on universally applied empirical thresholds.