Reduction of microemulsion propofol-induced injection pain via target-controlled remifentanil infusion.

The intravenous injection of microemulsion propofol to induce anaesthesia causes more intense and frequent pain than lipid emulsion propofol. This study investigated whether different target effect-site concentrations of remifentanil could prevent pain due to microemulsion propofol injection. In total, 96 patients were randomly assigned to one of three groups receiving target effect-site concentrations of remifentanil 0 (control group), 4 or 6 ng/ml, followed by injection with microemulsion propofol. Remifentanil pretreatment significantly reduced the incidence and severity of injection pain compared with the control group. Although no difference in pain reduction between the two remifentanil-treated groups was observed, those receiving a target effect-site concentration of 6 ng/ml exhibited an increased rate of complications, compared with those receiving 4 ng/ml. In conclusion, prior administration of remifentanil at a target effect-site concentration of 4 ng/ml is a useful strategy to decrease the injection pain of microemulsion propofol.