Intracranial Hypertension and Cerebral Autoregulation: A Systematic Review and Meta-Analysis

OBJECTIVE: To present a systematic review and meta-analysis to establish the relation between cerebral autoregulation (CA) and intracranial hypertension. METHODS: An electronic search using the term "Cerebral autoregulation and intracranial hypertension" was designed to identify studies that analyzed cerebral blood flow autoregulation in patients undergoing intracranial pressure (ICP) monitoring. The data were used in meta-analyses and sensitivity analyses. RESULTS: A static CA technique was applied in 10 studies (26.3%), a dynamic technique was applied in 25 studies (65.8%), and both techniques were used in 3 studies (7.9%). Static CA studies using the cerebral blood flow technique revealed impaired CA in patients with an ICP >= 20 (standardized mean difference [SMD] 5.44%, 95% confidence interval [CI] 0.25-10.65, P = 0.04); static CA studies with transcranial Doppler revealed a tendency toward impaired CA in patients with ICP >= 20 (SMD -7.83%, 95% CI -17.52 to 1.85, P = 0.11). Moving correlation studies reported impaired CA in patients with ICP >= 20 (SMD 0.06, 95% CI 0.07-0.14, P < 0.00001). A comparison of CA values and mean ICP revealed a correlation between greater ICP and impaired CA (SMD 5.47, 95% CI 1.39-10.1, P = 0.01). Patients with ICP >= 20 had an elevated risk of impaired CA (OR 2.27, 95% CI 1.20-4.31, P = 0.01). CONCLUSIONS: A clear tendency toward CA impairment was observed in patients with increased ICP.