Pressure-derived versus pressure wave amplitude–derived indices of cerebrovascular pressure reactivity in relation to early clinical state and 12-month outcome following aneurysmal subarachnoid hemorrhage

Abstract

Object Indices of cerebrovascular pressure reactivity (CPR) represent surrogate markers of cerebral autoregulation. Given that intracranial pressure (ICP) wave amplitude–guided management, as compared with static ICP-guided management, improves outcome following aneurysmal subarachnoid hemorrhage (SAH), indices of CPR derived from pressure wave amplitudes should be further explored. This study was undertaken to investigate the value of CPR indices derived from static ICP–arterial blood pressure (ABP) values (pressure reactivity index [PRx]) versus ICP-ABP wave amplitudes (ICP-ABP wave amplitude correlation [IAAC]) in relation to the early clinical state and 12-month outcome in patients with aneurysmal SAH. Methods The authors conducted a single-center clinical trial enrolling patients with aneurysmal SAH. The CPR indices of PRx and IAAC of Week 1 after hemorrhage were related to the early clinical state (Glasgow Coma Scale [GCS] score) and 12-month outcome (modified Rankin Scale score). Results Ninety-four patients were included in the study. The IAAC, but not the PRx, increased with decreasing GCS score; that is, the higher the IAAC, the worse the clinical state. The PRx could differentiate between survivors and nonsurvivors only, whereas the IAAC clearly distinguished the groups “independent,” “dependent,” and “dead.” In patients with an average IAAC ≥ 0.2, mortality was approximately 3-fold higher than in those with an IAAC < 0.2. Conclusions The IAAC, which is based on single ICP-ABP wave identification, relates significantly to the early clinical state and 12-month outcome following aneurysmal SAH. Impaired cerebrovascular pressure regulation during the 1st week after a bleed relates to a worse outcome. Clinical trial registration no.: NCT00248690.