Cerebral perfusion pressure threshold to prevent delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Abstract Objective To seek a cerebral perfusion pressure (CPP) threshold that can reduce the occurrence of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). Methods We analyzed the clinical data of patients with the diagnosis of aSAH and underwent CPP monitoring in our department from February 2014 to December 2015. CPP was divided into four specified thresholds by every 10 mmHg increments, which were from 50 mmHg to 80 mmHg. The totally time ratio of CPP below each threshold was calculated. The correlation between the time ratio and DCI were analyzed using binary logistic regression. And receiver operating characteristic curve was performed to identify the cutoff time ratios at higher risk of DCI. Results Finally, 17 patients developed DCI from 60 patients who were recruited. The time ratios of CPP which was below 50 mmHg, 60 mmHg and 70 mmHg were found predictors of DCI by the binary logistic regression. The cutoff time ratios were 0.4% (AUC = 0.777), 7.0% (AUC = 0.702), 28.7% (AUC = 0.696) respectively. While at the level of 80 mmHg, the cutoff time ratio was 65% (AUC = 0.595). It was not related to DCI (P = 0.167). Patients suffered from DCI had a worse outcome than who did not at 3 month after aSAH (P = 0.018). Conclusion Time ratios at higher risk of DCI had a positive relationship with the CPP thresholds. Keeping CPP above 70 mmHg may be helpful to prevent DCI after aSAH, but it still needs further investigation.