Effect of Lidocaine on Postoperative Pain in Elderlypatients Undergoing Colorectal Cancer Surgery

Patients in the lidocaine groups, lidocaine 1.5mg/kg/h was continuously infused (using ideal body weight) during the whole procedure, postoperative analgesia pump with lidocaine (lidocaine 50mg/kg, sufentanil 2ug/kg, glassetron 12mg), diluted to 200ml with saline until 72h after surgery. Blood samples will be collected from some patients in the lidocaine group for the measurement of lidocaine plasma concentration.

In the placebo group, the same volume of normal saline will be administered during anesthesia. The postoperative PCIA device will contain sufentanil 2 μg/kg, granisetron 12 mg diluted to 200 mL in 0.9% normal saline solution with a total volume of 200 mL.