Optimal cerebral perfusion pressure during induced hypertension and its impact on delayed cerebral infarction and functional outcome after subarachnoid hemorrhage

Disturbed cerebral autoregulation (CA) increases the dependency of cerebral blood flow (CBF) on cerebral perfusion pressure (CPP). Thus, induced hypertension (IHT) is used to prevent secondary ischemic events. The pressure reactivity index (PRx) assesses CA and can determine the optimal CPP (CPPopt). This study investigates CPPopt in patients with subarachnoid hemorrhage (SAH) treated with IHT and its impact on delayed cerebral infarction and functional outcome. This is a retrospective observational study including SAH patients treated between 2012 and 2020. PRx defines the correlation coefficient of intracranial pressure (ICP) and the mean arterial pressure (MAP). The CPP corresponding to the lowest PRx-value describes CPPopt. Primary outcome parameters were deleayed cerebral infarction and functional outcome. In patients without IHT, higher deviations of measured CPP from CPPopt were associated with delayed cerebral infarction (p = 0.001). Longer time spent with a CPP below the calculated CPPopt during IHT led to an increased risk of developing delayed cerebral infarction (r = 0.39, p = 0.002). A larger deviation of measured CPP from CPPopt correlated with an unfavorable outcome in patients treated with IHT (p = 0.04) and without IHT (p = 0.0007). Patients with severe aneurysmal SAH may benefit from an individualized CPP management and the calculation of CPPopt may help to guide IHT.