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: The lidocaine group had a lower incidence of postoperative delirium (8.9% vs 20.7%; RR, 0.43; 95% CI, 0.23-0.81; 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.