Dexmedetomidine Induces Low Patient State Indices While Preventing the Development of Postoperative Delirium in Older Patients Undergoing General Anesthesia - A Secondary Analysis of a Randomized Controlled Trial (NEUPRODEX)

Background: Dexmedetomidine may have a delirium preventive effect in high-risk surgical patients. Accurate frontal EEG-guided anesthesia can decrease the incidence of postoperative delirium by avoiding too deep anesthesia. Aim of our study is to evaluate the incidence of postoperative delirium under intraoperative frontal EEG neuromonitoring during general anesthesia with dexmedetomidine. Methods: : A secondary analysis of a single-center, randomized, double-blinded, placebo-controlled trial. Patients > 60 years were included with either abdominal or cardiac surgery, receiving intraoperative dexmedetomidine or placebo. Delirium incidence was measured up to the fifth postoperative day. Anesthetic depth was measured as Patient State Index (PSi™) every 15 minutes during surgery using EEG-based neuromonitoring. Results: : Of the 60 patients included, the incidence of postoperative delirium was significantly reduced in the dexmedetomidine group (n=28) vs. the control group (n=32) (p=0.031). A PSi less than 25 at least once was seen in 85.2% of the verum group and 58.1% of the placebo group (p=0.024). The mean (SD) PSi value in the dexmedetomidine group was 28.17 (10.35) and 33.55 (11.31) in the placebo group using mixed-model ANOVA. Conclusions: : Intraoperative Dexmedetomidine reduces the incidence of postoperative delirium in older patients at risk, although presenting with lower intraoperative PSi levels.