Reduction of pain during induction with target-controlled propofol and remifentanil

Background. Pain on injection of propofol is unpleasant. We hypothesized that propofol infu-sion pain might be prevented by infusing remifentanil before starting the propofol infusion in a clinical setting where target-controlled infusions (TCI) of both drugs were used. A prospective, randomized, double-blind, placebo-controlled trial was performed to determine the effect-site concentration (Ce) of remifentanil to prevent the pain without producing complications. Methods. A total of 128 patients undergoing general surgery were randomly allocated to receive normal saline (control) or remifentanil to a target Ce of 2 ng ml21 (R2), 4 ng ml21 (R4), or 6 ng ml21 (R6) administered via TCI. After the target Ce was achieved, the infusion of propofol was started. Remifentanil-related complications were assessed during the remifentanil infusion, and pain caused by propofol was evaluated using a four-point scale during the propo-fol infusion. Results. The incidence of pain was significantly lower in Groups R4 and R6 than in the control and R2 groups (12/32 and 6/31 vs 26/31 and 25/32, respectively, P,0.001). Pain was less severe in Groups R4 and R6 than in the control and R2 groups (P,0.001). However, both incidence and severity of pain were not different between Groups R4 and R6. No significant complications were observed during the study. Conclusions. During induction of anaesthesia with TCI of propofol and remifentanil, a signifi-cant reduction in propofol infusion pain was achieved without significant complications by prior administration of remifentanil at a target Ce of 4 ng ml21.