Cerebral Autoregulation in the Prediction of Delayed Cerebral Ischemia and Clinical Outcome in Poor-Grade Aneurysmal Subarachnoid Hemorrhage Patients

Objectives: Pressure reactivity index and oxygen reactivity index are used to assess cerebral autoregulation after acute brain injury. The value of autoregulation indices in the prediction of delayed cerebral ischemia and outcome in patients with subarachnoid hemorrhage is still inconclusive. In this study, we aimed to focus on the predictive value of the first 72 hours commonly referred to as "early brain injury" in comparison to the overall monitoring period. Design: Retrospective observational cohort study. Setting: Neurocritical care unit at a tertiary academic medical center. Patients: Forty-three consecutive poor-grade patients with nontraumatic subarachnoid hemorrhage admitted between 2012 and 2016 undergoing continuous high-frequency monitoring. Interventions: High-frequency monitoring includes arterial blood pressure, intracranial pressure, and brain tissue oxygen tension. Pressure reactivity index and oxygen reactivity index were evaluated as moving correlation coefficient between mean arterial pressure/intracranial pressure and cerebral perfusion pressure/brain tissue oxygen tension, respectively. Measurements and Main Results: Median autoregulation monitoring time was 188 ± 91 hours per patient. Initial pressure reactivity index was 0.31 ± 0.02 and decreased significantly to 0.01 ± 0.01 (p

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