"Optimal Cerebral Perfusion Pressure" in Poor Grade Patients After Subarachnoid Hemorrhage

Cerebrovascular pressure reactivity depends on cerebral perfusion pressure (CPP), with the optimal CPP (CPPopt) defined as pressure at which cerebrovascular reactivity is functioning optimally, reaching minimal value of pressure reactivity index (PRx). The study investigates the association between vasospasm, PRx, and CPPopt in poor grade patients (WFNS 4&5) after subarachnoid hemorrhage (SAH). Data of intracranial pressure (ICP), arterial blood pressure (ABP), and flow velocities (FV) in the Middle Cerebral Artery (MCA) on transcranial Doppler from 42 SAH patients were analyzed retrospectively. PRx was calculated as a correlation coefficient between 10 s mean values of ABP and ICP calculated over a moving 3 min window. Data recorded during the first 48 h were available in 25 cases and during the first 3 days in 29 patients. Recordings obtained from day 4 to day 24 were available in 23 patients. PRx at optimal CPP measured during the first 48 h showed better cerebrovascular reactivity in patients who were alive at 3 months after ictus than in those who died (PRx value -0.17 +/- A 0.05 vs. 0.1 +/- A 0.09; P < 0.01). PRx below zero at CPPopt during the first 48 h had 87.5% positive predictive value for survival. CPPopt was lower before than during vasospasm (78 +/- A 3 mmHg, N = 29 vs. 98 +/- A 4 mmHg; N = 17, P < 0.0001). The overall correlation between CPPopt and Lindegaard ratio was positive (R = 0.39; P < 0.01; N = 45). Most WFNS 4&5 grade SAH patients with PRx below zero at optimal CPP during the first 48 h after ictus survived. Optimal CPP increases during vasospasm.