Monitoring Cerebral Autoregulation After Subarachnoid Hemorrhage

Introduction : Delayed cerebral ischemia (DCI) is a major contributor to morbidity and mortality after subarachnoid hemorrhage (SAH). Data challenge vasospasm being the sole cause of ischemia and suggest other factors. We tested the hypothesis that early autoregulatory failure might predict DCI. Methods : This is a prospective observational study of cerebral autoregulation following SAH in which the primary end point was DCI at 21 days. Cox proportional hazards and multivariate models were used and the benefit of using multiple indices was analyzed. Results : Ninety-eight patients were included in the study. There was an increased risk of DCI with early dysautoregulation (odds ratio [OR]: 7.46, 95% confidence interval [CI]: 3.03-18.40 and OR: 4.52, 95 % CI: 1.84-11.07 for the transcranial Doppler index of autoregulation [Sxa] and near-infrared spectroscopy index of autoregulation [TOxa], respectively), but not vasospasm (OR: 1.36, 95 % CI: 0.56-3.33). Sxa and TOxa remained independent predictors of DCI in the multivariate model (OR: 12.66, 95 % CI: 2.97-54.07 and OR: 5.34, 95 % CI: 1.25-22.84 for Sxa and TOxa, respectively). There was good agreement between different indices. All 13 patients with impaired autoregulation in all three methods developed DCI. Conclusions : Disturbed autoregulation in the first 5 days after SAH is predictive of DCI. Although colinearities exist between the methods assessed, multimodal monitoring of cerebral autoregulation can aid the prediction of DCI.