Efficacy of cold propofol and lidocaine on propofol injection-induced pain

Objective To assess the efficacy of cold propofol and lidocaine in minimizing pain associated with injection of propofol. Methods One hundred twenty patients were enrolled in this study with an American Society of Anesthesiologists( ASA) physical status class I or II for general anesthesia. All patients aged 30-60 years old were randomly allocated into three groups( n = 40,in each). The control and lidocaine group patients received 2 mg /kg propofol that had been stored at room temperature( 20- 23 ℃); while the cold group received cold( 4 ℃) propofol. The pain intensity and incidence were then evaluated using a 4- point verbal rating scale. Also,blood pressure and heart rate were measured at the baseline,after intravenous injection of propofol and before intubation. Results The incidence of pain was significantly reduced in the groups that received cold propofol and lidocaine compared to the control group( 32. 5% and 37. 5% vs. 70%,respectively). Moreover,the severity of pain was significantly lower in the groups that received cold propofol and lidocaine compared to the control group. Conclusion Cold propofol and pretreatment with lidocaine can effectively reduce the incidence and severity of pain upon the injection of propofol.