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

Abstract

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.

Keywords: Induced hypertension; Optimal cerebral perfusion pressure; Perfusion pressure index; Subarachnoid hemorrhage.

Fig. 1

Study flowchart.

Fig. 2

Comparison of average values of arterial blood pressure (ABP) showed significantly higher values in the IHT group than in the no IHT group (graph A), average values of intracranial pressure (ICP) were significantly higher in the no IHT group than in the IHT group (graph B), and average values of blood flow velocities (BFV) measured by transcranial Doppler sonography (TCD) showed higher values in the IHT group, but the difference was not statistically significant (graph C).

Fig. 3

Time trend of cerebral perfusion pressure (CPP) values and optimal cerebral perfusion pressure (CPPopt) values within the first 14 days after ictus in the entire patient cohort (upper graph) and in the group treated with induced hypertension (IHT) during the time mean arterial pressure was increased by the administration of norepinephrine (lower graph). The lines represent the mean values (for each day).

Fig. 4

CPP and CPPopt values over the course of 14 days in patients with IHT and without IHT, patients with DCI and without DCI, and in patients with favorable and unfavorable outcome. The lines represent the mean values (for each day), and the colored areas represent the 95% confidence interval.