Relationship Between Intraoperative Bispectral Index and Consciousness Recovery in Patients With Hepatic Encephalopathy Undergoing Liver Transplant: A Retrospective Analysis

Background. Although liver transplant (LT) improves liver function and restores symptoms of hepatic encephalopathy (HE), there is no index to predict the recovery of consciousness in patients with HE during LT. In this study, we evaluated the relationship between intraoperative bispectral index (BIS) values and the recovery of consciousness in patients with HE who were undergoing LT. Methods. Patients with HE who underwent LT from June 2011 to December 2017 at our institution were enrolled. A total of 64 patients were enrolled, and, using the West Haven Criteria, they were divided into 2 groups: nonsevere HE group (n = 26), grades 1 to 2 HE; and severe HE group (n = 38), grades 3 to 4 HE. Grade of HE, intraoperative BIS, minimum alveolar concentration values, postoperative Glasgow Coma Scale (GCS) score, and the time to recover consciousness were compared. Results. The severe HE group showed lower BIS after anesthetic induction compared with the nonsevere HE group (P = .005). In the severe HE group, intraoperative BIS gradient (the difference between values measured 4 hours after reperfusion and immediately after anesthesia induction) was significantly larger than in the nonsevere HE group (P = .001). Time to recovery of consciousness was prolonged in the severe HE group (P = .002). Model for End-Stage Liver Disease (MELD) score and the GCS score at 24 hours after LT were associated with delayed recovery of consciousness (MELD score: hazard ratio, 1.103; 95% CI, 1.002-1.214; P = .046; GCS score at 24 hours after LT: hazard ratio, 0.688; 95% CI, 0.566-0.835; P < .001). Conclusions. Our study indicated that BIS values immediately after anesthesia induction were significantly lower in patients with severe HE. However, it did not show a significant relationship with the time to recovery of consciousness after LT. Multivariate analysis demonstrated that MELD score and GCS score at 24 hours after LT were associated with the time to recovery of consciousness.