a Pilot Study of Lidocaine Infusion for Postoperative Analgesia in Elderly Patients With Colorectal Cancer Surgery

patients who meet the enrollment criteria will be randomized 1:1:1:1 to the different doses of lidocaine or the placebo group. In the lidocaine groups, at the beginning of surgery, lidocaine 0.5mg/kg, 1.0mg/kg, and 1.5mg/kg per hour were continuously infused (using ideal body weight) respectively during the whole procedure. In contrast, the control group was infused with the same dose of normal saline. All the infusion procedures will be stopped at the end of surgery