Remote Ischemic Conditioning After Subarachnoid Hemorrhage: A Systematic Review and Meta-analysis

Remote ischemic conditioning (RIC), an intervention in which brief episodes of ischemia are applied to an organ or tissue to induce remote organs' tolerance of subsequent ischemic injury, has shown potential in reducing the incidence of delayed cerebral ischemia (DCI) secondary an aneurysmal subarachnoid hemorrhage (aSAH). This review aimed to evaluate the effectiveness of RIC in patients with SAH.

A comprehensive search was conducted to identify peer-reviewed randomized controlled trials (RCT) and non-randomized studies comparing RIC with no conditioning or sham procedures in adults with SAH. Outcomes of interest were mortality, DCI, and neurological status. Risk of bias was assessed using the Cochrane RoB 2.0 tool for RCTs and Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) for non-randomized studies. We conducted random-effects meta-analysis to obtain pooled risk ratios (RR) and assessed certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

Four clinical trials and one cohort study with a total of 200 patients fulfilled selection criteria and were included for synthesis. We did not find a statistically significant effect of RIC on mortality (RR = 0.69, 95% CI 0.21-2.27), cerebral infarction (RR = 1.04, 95% CI 0.44-2.45)m or unfavorable neurological outcomes (RR = 0.73, 95% CI 0.51-1.05). Significant variability in outcome definitions and reporting precluded pooled analysis for vasospasm.

Currently, evidence does not support the efficacy of RIC in the management of SAH. The lack of standardized protocols and clinical definitions limits the ability to confirm a therapeutic effect. More rigorous and uniform trials are necessary to definitively establish its potential benefits.