Cerebral perfusion pressure and ddelayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Abstract

Background Whether delayed cerebral ischemia (DCI) mediates the relationship between Hunt and Hess grade and outcomes after aneurysmal subarachnoid hemorrhage remains unknown. Objectives To investigate the relationship between cerebral perfusion pressure, DCI, Hunt and Hess grade, and outcomes after aneurysmal subarachnoid hemorrhage. Methods DCI was defined as neurological deterioration due to impaired cerebral blood flow. Relationships between minimum cerebral perfusion pressure and onset and occurrence of DCI were tested by using logistic regression and the accelerated failure time model. The mediation effect of DCI on relationships between Hunt and Hess grade and outcomes was tested by using the bootstrap confidence interval. Outcomes at 3 and 12 months included mortality and neuropsychological, functional, and physical outcomes. Results DCI occurred in 211 patients (42%). About one-third of the patients had poor functional outcome at 3 (32%) and 12 (30%) months. Impaired neuropsychological outcome was observed in 33% of patients at 3 months and 17% at 12 months. For every increase of 10 mm Hg in cerebral perfusion pressure, odds for DCI increased by 2.78 (95% CI, 2.00-3.87). High perfusion pressure was associated with earlier onset of DCI (P < .001). Conclusions DCI does not mediate the relationship of Hunt and Hess grade to functional outcome or death. The relationship between cerebral perfusion pressure and DCI was most likely due to induced hypertension and hypervolemia. Clinical guidelines may need to include limits for induced hypertension.