Induced Hypertension does not significantly increase cerebral perfusion after aneurysmal subarachnoid hermorrhage
Induced hypertension is a common treatment modality in patients with delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (SAH). The efficacy of this therapeutic modality is based on limited case series. Gathier et al. randomized aneurysmal SAH to induced (N=12) or no induced hypertension (N=13) at the onset of DCI with the primary outcome measure being changes in cerebral blood flow (CBF). The authors found that the mean arterial blood pressure was 12 mm Hg higher in the hypertension group than in the control group. In this limited study, there was no significant difference in CBF between the induced (0.1 ml/100g per s; range -31 to 43) and non-induced cohorts (-8.5 ml/100g per s; range -42 to 30). This preliminary study provides further data for a power analysis to plan a randomized clinical trial. Based on these results, 225 to 250 patients per group would be needed to find a statistically significant difference in overall CBF, and a larger cohort would be necessary to find a difference in functional outcomes. Further studies are indicated to determine the optimal agents for blood pressure induction and optimal thresholds for blood pressure augmentation.