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. Subsequently, all subjects will receive an analgesic device named Patient-Controlled Intravenous Analgesia pump, briefly, PCIA pump during the first 72 postoperative hours. PCIA pump contains lidocaine 30mg/kg, sufentanil 2 μg/kg, and granisetron 12 mg diluted to 200 mL in 0.9 % normal saline, while in the placebo group, the lidocaine will be replaced with the equal dose of 0.9% normal saline and other components unchanged. All the background infusions of PCIA will be set at 2 ml/h, the bolus volume of each PCIA press is 2 ml and the lockout interval is 15 min.

Inclusion criteria

• Age over 60 years old；
• American Society Anesthesiologygist(ASA)I~III；
• Patients scheduled for colorectal cancer surgery；
• The surgery takes more than two hours

Exclusion criteria

• BMI≥30kg/㎡or BMI≤18kg/㎡；
• Combined with other organ malignancies；
• Chronic opioid use, substance abuse, contraindication to the use or incompatibility of any drug in the study；
• Patients with liver and kidney insufficiency and chronic pain at the surgical site；
• Accompanied by severe heart disease (such as severe atrioventricular block, severe heart failure, etc.)；
• A history of uncontrolled seizures or acute porphyria；
• Patients who have taken other experimental drugs or participated in or are participating in other clinical trials within 3 months before being enrolled in the study