Pain reduction on injection of microemulsion propofol via combination of remifentanil and lidocaine

BACKGROUND: Microemulsion propofol produces more frequent and severe pain upon injection than lipid emulsion propofol. This study examined the analgesic effect of lidocaine-premixed microemulsion propofol in patients pretreated with remifentanil. The induction of anesthesia with this combination was compared with microemulsion propofol accompanied with either remifentanil or lidocaine. METHODS: One hundred twenty patients aged between 20-65 years old were allocated randomly into one of three groups (n = 40, in each). The patients in the remifentanil group received remifentanil 0.5 µg/kg IV for 30 seconds before a microemulsion propofol injection. The patients in the lidocaine group received propofol 2 mg/kg premixed with 40 mg lidocaine over a 60 second period. The patients in the combination group received both remifentanil and lidocaine. RESULTS: There was a significantly lower incidence of microemulsion propofol injection pain (severity 2 or more) in the combination group (12.5%) than in the remifentanil and lidocaine groups (90% and 65%, respectively, P < 0.05). The incidence of moderate pain disappeared completely in the combination group (0%) compared to that in the remifentanil and lidocaine group (32.5% and 20%, respectively, P < 0.05). Severe pain did not appear in any of the three groups. There were no complications on the injection site in the lidocaine alone and combination groups. CONCLUSIONS: The combination of microemulsion propofol premixed with lidocaine after a pretreatment with remifentanil was more effective in reducing the incidence of pain upon the injection of microemulsion propofol than either treatment alone.