Abstract 147: Individualized Blood Pressure Management After Subarachnoid Hemorrhage Using Real-time Autoregulation Monitoring: A Pilot Study Using NIRS and ICP-derived Limits of Autoregulation

Abstract

Introduction: Optimal blood pressure (BP) targets in the early stages of aneurysmal subarachnoid hemorrhage (aSAH) prior to occurrence of clinical vasospasm have not been well established. It is unclear which patients are ideal candidates for therapeutic BP manipulation. To determine the association of individualized autoregulation-based BP targets on functional outcome, we continuously measured limits of autoregulation (LA) in SAH patients. Methods: We prospectively enrolled 7 patients with aSAH who underwent multimodality neuromonitoring. Autoregulatory function was continuously measured by interrogating changes in arterial BP and intracranial pressure (ICP) or the near-infrared spectroscopy (NIRS) derived tissue-oxygenation index. Resulting indices of autoregulation were used to identify the BP of individual patients at which autoregulation was best preserved (MAPopt). A time trend of MAPopt with upper and lower limits of autoregulation (ULA, LLA) provided dynamically updated targets for BP control, and percent time within and outside LA was computed for each patient (Fig 1A). Functional outcome was assessed using the modified Rankin Scale (mRS) at discharge and 90 days. Results: Identification of MAPopt was possible in all patients (mean age 59, 3 male, mean WFNS 2.1) with an average monitoring time of 62.8h starting within 24h of SAH. A high degree of correlation was observed between invasive (ICP) and non-invasive (NIRS) modalities for calculation of MAPopt (r=0.91, p=0.01). The median time spent within optimal BP range was 51.4%, and percent time outside LA showed a linear association with worse functional outcomes (Fig 1B). Conclusions: Calculation of personalized autoregulation-based BP targets after SAH is feasible; BP management outside LA may increase the risk for worse functional outcomes. Non-invasive NIRS-based methods could provide a reasonable alternative for patients for whom invasive intracranial monitoring is not indicated.