Continuous Monitoring of Cerebrovascular Autoregulation After Subarachnoid Hemorrhage by Brain Tissue Oxygen Pressure Reactivity and Its Relation to Delayed Cerebral Infarction

Background and Purpose— Disturbances of cerebrovascular autoregulation are thought to be involved in delayed cerebral ischemia and infarction after aneurysmal subarachnoid hemorrhage (SAH). We hypothesized that the continuous monitoring of brain tissue oxygen (PtiO2) pressure reactivity enables the detection of impaired autoregulation after SAH and that impaired autoregulation is associated with delayed infarction. Methods— In 67 patients after severe SAH, continuous monitoring of cerebral perfusion pressure (CPP) and PtiO2 was performed for an average of 7.4 days. For assessment of autoregulation, the index of PtiO2 pressure reactivity (ORx) was calculated as a moving correlation coefficient between values of CPP and PtiO2. Higher ORx values indicate disturbed autoregulation, whereas lower ORx values signify intact autoregulation. Results— Twenty patients developed delayed cerebral infarction, and 47 did not. Mean ORx was significantly higher in the infarction group compared with the noninfarction group ...