Determining Optimal Mean Arterial Pressure After Cardiac Arrest: A Systematic Review

The use of cerebral autoregulation monitoring to identify patient-specific optimal mean arterial pressure (MAP_OPT) has emerged as a technique to augment cerebral oxygen delivery in post-cardiac arrest patients. Our systematic review aims to determine (a) the average MAP_OPT in these patients, (b) the feasibility of identifying MAP_OPT, (c) the brain tissue oxygenation levels when MAP is within proximity to the MAP_OPT and (d) the relationship between neurological outcome and MAP_OPT-targeted resuscitation strategies. We carried out this review in accordance with the PRISMA guidelines. We included all studies that used cerebral autoregulation to determine MAP_OPT in adult patients (> 16 years old) who achieved return of spontaneous circulation (ROSC) following cardiac arrest. All studies had to include our primary outcome of MAP_OPT. We excluded studies where the patients had any history of traumatic brain injury, ischemic stroke or intracranial hemorrhage. We identified six studies with 181 patients. There was wide variability in cerebral autoregulation monitoring methods, length of monitoring, calculation and reporting of MAP_OPT. Amongst all studies, the median or mean MAP_OPT was consistently above 65 mmHg (range 70-114 mmHg). Definitions of feasibility varied among studies and were difficult to summarize. Only one study noted that brain tissue oxygenation increased as patients' MAP approached MAP_OPT. There was no consistent association between targeting MAP_OPT and improved neurological outcome. There is considerable heterogeneity in MAP_OPT due to differences in monitoring methods of autoregulation. Further research is needed to assess the clinical utility of MAP_OPT-guided strategies on decreasing secondary injury and improving neurological outcomes after ROSC.