Noninvasive Cerebral Imaging and Monitoring Using Electrical Impedance Tomography During Total Aortic Arch Replacement

Abstract

Objective: To explore the feasibility of using electrical impedance tomography (EIT) to provide noninvasive cerebral imaging and monitoring in total aortic arch replacement (TAAR). Design: A prospective, observational study. Setting: Department of cardiovascular surgery in a university hospital. Participants: Forty-two patients undergoing TAAR using hypothermic circulatory arrest and unilateral antegrade cerebral perfusion. Interventions: None. Measurements and Main Results: Cerebral impedances of the patients were monitored intraoperatively by an EIT system. The prognostic information of the patients, including postoperative neurological dysfunction, was collected during their hospitalizations. Eight (19.0%) subjects had at least 1 postoperative neurological dysfunction complication. The results show that cerebral impedance was related negatively to perfusion flow, and the gradual increase in cerebral resistivity might reflect the evolving process of brain tissue caused by hypoxia. Maximum resistivity asymmetry index was extracted from the reconstructed images to quantify the pathological changes of the brain. The area under the receiver operating characteristic curve of maximum resistivity asymmetry index for postoperative neurological dysfunction was 0.864. In multivariate logistic regression, maximum resistivity asymmetry index was the strongest independent predictor of neurological dysfunction with an odds ratio of 24.3. Conclusion: EIT is a promising technique to provide noninvasive cerebral imaging and monitoring in TAAR.