Effect of Intraoperative Intravenous Lidocaine on Postoperative Delirium in Elderly Patients Undergoing Posterior Lumbar Interbody Fusion

Purpose: This study aimed to evaluate the effect of intraoperative intravenous (IV) lidocaine on the incidence of postoperative delirium (POD) in elderly patients undergoing major spinal surgery. Patients and Methods: In this prospective, single-center randomized clinical trial, elderly patients scheduled for elective posterior lumbar interbody fusion (PLIF) with instrumentation spanning two or more vertebral segments were enrolled. A total of 270 patients were randomized to receive either intravenous lidocaine (Group L) or saline (Group C). Group L received lidocaine at a bolus dose of 1.5 mg/kg before induction, followed by continuous infusion at 1.5 mg/kg/h until the end of surgery, while Group C received an equivalent volume of saline. All patients underwent standardized general anesthesia. The primary outcome was the incidence of postoperative delirium (POD) within 5 days after surgery. Secondary outcomes included delirium severity, onset, duration, and subtype (hypoactive, hyperactive, or mixed), postoperative visual analog scale (VAS; 0-100 mm) pain scores, intraoperative anesthetic consumption, 24-hour sufentanil consumption and patient-controlled intravenous analgesia (PCIA) attempts, and perioperative adverse events. Results: < 0.05). Among patients who developed delirium, the duration was comparable between groups, while severity scores were higher and time to onset was shorter in the control group. Within the first 24 hours postoperatively, the lidocaine group had lower VAS scores, fewer PCIA attempts, and a reduced cumulative sufentanil dose. Opioid-related adverse events, including nausea and vomiting, were less frequent, with no cases of local anesthetic toxicity, and the overall hospital stay was comparable. Conclusion: In elderly patients undergoing PLIF, intraoperative intravenous lidocaine (1.5 mg/kg administered before induction, followed by continuous infusion at 1.5 mg/kg/h until the end of surgery) lowered the occurrence of postoperative delirium (POD) within the first 5 days after surgery.