Anesthetic Depth Monitoring Decreased the Incidence of Postoperative Delirium Assessed in Nursing Delirium Screening Scale in Elective Non-Cardiac Surgical Patients Receiving Intravenous Patient-Controlled Analgesia

Background To identify the impact of processed electroencephalogram (pEEG)-guided anesthesia on postoperative delirium (POD) assessed by NuDESC, postoperative analgesic requirements, and the incidence of postoperative nausea/vomiting (PONV) in the elective non-cardiac surgical patients with intravenous patient-controlled analgesia (IVPCA) in the wards. Methods In this retrospective observational study, the anesthesiologists were free to use M-Entropy™, an pEEG device, to monitor the depth of anesthesia intraoperatively during the period (September 2015 ~ February 2018). Acute pain service team assessed the analgesic/side effects of IVPCA and POD at least twice daily for 3 days postoperatively. POD was screened by Nursing Delirium Screening Scale (NuDESC) (0-10). Pain severity was measured by an 11-point verbal numerical rating scale (0–10). Results A total of 1178 patients (≧60 years) were enrolled and divided to Entropy (749 patients) vs. non-Entropy group (429 patients). Multivariate logistic analysis showed that age (≧70), surgical types (non-joint), intraoperative highest minimum alveolar concentration (MAC) (<0.9MAC) and the POD incidence were independent predictors for group differences (multiple odds ratio and 95% confidence interval: 5.99, 4.34-8.29; 2.01, 1.49-2.72; 6.84, 4.38-10.67; 0.09, 0.04-0.19). The POD incidence in Entropy group (2.2%, 17 patients) was significantly lower than that in non-Entropy group (6.7%, 29 patients) (p <0.001). However, pEEG-guided anesthesia did not affect the phenomenological characteristics of POD. In addition, intraoperative pEEG-guided anesthesia did not reduce total morphine dose of IVPCA, the incidence of PONV and pain severity. Conclusions Processed EEG-guided anesthesia decreased POD incidence assessed in NuDESC in IVPCA patients undergoing elective non-cardiac surgery returning to the common ward. In addition, it did not reduce postoperative pain severity, postoperative analgesic requirements and PONV incidence. More researches are needed to investigate the effects of pEEG-guided anesthesia on POD and other postoperative conditions.