Purpose: This study was performed to evaluate the effects of intraoperative intravenous lidocaine on postoperative delirium in elderly patients with hip fracture.

Patients and methods: In total, 100 elderly patients undergoing hip fracture surgery were randomized to the lidocaine group (Group L) or saline (control) group (Group C). Before anesthetic induction, Group L received lidocaine at 1 mg/kg for more than 10 minutes followed by continuous infusion at 1.5 mg/kg/h until the end of surgery. Group C received normal saline, and the injection methods were consistent with those in Group L. General anesthesia was induced with propofol, sufentanil, and cis-atracurium. Anesthesia was maintained by propofol and remifentanil. The primary outcome was the incidence of postoperative delirium in the first 7 postoperative days. The secondary outcomes included the severity of delirium, onset and duration of delirium, emergence agitation, adverse events, total propofol dose, intraoperative opioid dosage, length of post-anesthesia care unit stay, extubation time, and patient satisfaction with postoperative pain management.

Results: All 100 patients completed the study. The incidence of postoperative delirium was lower in Group L than in Group C (14% vs 36%, P = 0.011). The delirium severity scores were lower in Group L (3 [3-4]) than in Group C (4 [4-5]) (P = 0.017). In addition, the incidences of hypertension, tachycardia, and emergence agitation were significantly lower in Group L than in Group C. No cases of local anesthetic toxicity occurred in either group.

Conclusion: Patients received lidocaine at 1 mg/kg for more than 10 minutes followed by continuous infusion at 1.5 mg/kg/h until the end of surgery, which can reduce the incidence of postoperative delirium in elderly patients undergoing hip fracture. In addition, the used regimen of lidocaine would not increase the risk of local anesthetic toxicity.