Relationship Between Cerebral Perfusion And Delayed Cerebral Infarction In ASAH

Background:Delayed cerebral infarction(DCI) is a critical factor that affects the prognosis of aneurysmal subarachnoid hemorrhage(a SAH) for leaking effective treatment. After aneurysm ruptured, cerebral blood flow(CBF) depends more on the cerebral perfusion pressure(CPP), because of vasospasm and impairment of cerebral vascular autoregulation. Cerebral perfusion deficiency may lead to cerebral ischemia, hypoxia, even irreversible cerebral infarction. Guidlines for management of a SAH have not recommended a proper CPP threshold to prevent DCI, and there are little literatures about these issues. Objective:We carried out this study to explore the relationship between cerebral perfusion pressure and delayed cerebral infarction, and preliminarily acquire an cerebral perfusion pressure threshold that can reduce delayed cerebral infarction. The secondary purpose of this study is to identify whether DCI depends not only on the CPP below a particular threshold, but also on the length of the time below the threshold. Methods:We prospectively collected the CPP and clinical data of patients suffered from a SAH who underwent CPP monitoring in our department from February 2014 to December 2014. CPP was divided in 7 specified thresholds by 5 mm Hg increments from 50 mm Hg to 80 mm Hg. The time below each threshold was calculated for every patient. And the correlation between the time below each level and DCI were analyzed using receiver operating characteristic and binary logistic regression. Results:A total of 44 patients who underwent CPP monitoring met include and exclude criteria. There were 11 developed DCI out of 44 patients. The cutoff percent time below 50 mm Hg~70mm Hg CPP threshold at higher risk of DCI were 0.25%(AUC=0.769), 2.9%(AUC=0.748), 10.1%(AUC=0.720), 15.4%(AUC=0.715), 23.7%(AUC=0.708) respectively and greater percent time below the thresholds were related to DCI in binary logistic regression. While at 75 mm Hg and 80 mm Hg level, the cutoff percent time were 48.8%(AUC=0.674) and 54.3%(AUC =0.623), no relationship were found to DCI in binary logistic regression(P=0.08,P=0.339). Conclusions: The development of DCI depends not only on the CPP threshold, but also on the length of the time below the threshold. Along with the CPP threshold level decreased, the capacity of ischemia tolerance fallen. In order to reduce the occurrence of DCI, constant low cerebral perfusion pressure should be avoided. Keeping CPP higher than 75 mm Hg may be helpful to prevent DCI, but it still needs more investigation. Acquiring ‘individual CPP’ via multiply monitoring may be more helpful.