Revisiting the oxygen reactivity index in traumatic brain injury: the complementary value of combined focal and global autoregulation monitoring – Critical Care
Background The oxygen reactivity index (ORx) reflects the correlation between focal brain tissue oxygen (pbtO2) and the cerebral perfusion pressure (CPP). Previous, small cohort studies were conflicting on whether ORx conveys cerebral autoregulatory information and if it is related to outcome in traumatic brain injury (TBI). Thus, we aimed to investigate these issues in a larger TBI cohort. Methods 425 TBI patients with intracranial pressure (ICP)- and pbtO2-monitoring for at least 12 h, who had been treated at Addenbrooke’s Hospital, Cambridge, UK, were included. Association between ORx and ICP, pressure reactivity index (PRx), CPP, ΔCPPopt (actual CPP-CPPopt [PRx based optimal CPP]), and pbtO2 were evaluated with generalized additive models (GAMs). Association between ORx and outcome (Glasgow Outcome Scale [GOS]) was investigated with logistic regressions and heatmaps for those 239 patients with GOS data. Results GAMs showed that ORx increased with higher ICP, PRx above + 0.30, CPP b
