To compare the severity of pain on injection of MCT/LCT propofol with lidocaine 20 mg, 40 mg, and without lidocaine.

Background: Intravenous injection of propofol produces pain. Many factors are involved and various techniques have been tried to minimize the propofol-induce pain with variable results.

Objective: To compare the severity of pain on injection of MCT/LCT propofol with lidocaine 20 mg, 40 mg, and without lidocaine.

Design: Randomize controlled trial. Method: Two hundred and ten ASA class I - III patients undergoing elective surgery were blinded and equally allocated into 3 groups. Patients in group N, L1, and L2 received MCT/LCT propofol 10 ml mixed with 0.9% NaCl 2 ml, 1% lidocaine 2 ml, and 2% lidocaine 2 ml respectively. Pain at time of propofol injection was assessed by blinded anesthesiologist on a four point scale ; 0 = no pain, 1 = mild pain, 2 = moderate pain, and 3 = severe pain. Results: Patient's demographic data of each group were similar. There were significant differences in the incidence of propofol injection without pain among groups (p<0.001). The numbers of patients who had moderate and severe pain in groups L1 and L2 were significantly less than those in group N (p<0.001). The mean blood pressure and heart rate were not significant differences in among groups. Conclusion : The amount of 20 mg, and 40 mg lidocaine to MCT/LCT propofol in our study is equally effective in decreasing pain and more effective than MCT/LCT propofol alone group significantly. They were no significant differences in hemodynamics change in among groups.

Inclusion Criteria:

• ASA class I - III patients
• undergoing elective surgery
• age 18-75 years

Exclusion Criteria:

• allergy to propofol and lidocaine
• abnormal liver and renal functions
• has psychological problem or drug abuse
• has recieved analgesic drug 2 weeks prior to surgery
• risk of aspiration