Half-effective target effect-site concentration of sufentanil inhibiting responses to insertion of SLIPA when combined with propofol given by target-controlled infusion

Abstract

Objective To determine the half-effective target effect-site concentration(EC50)of sufentanil inhibiting responses to insertion of Streamlined Liner of the Pharynx Airway(SLIPA)when combined with propofol given by target-controlled infusion(TCI). Methods Twenty-eight patients, aged 35-55 yr, with body mass index<30 kg/m2, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, scheduled for elective hysteroscopic surgery, were selected.Sufentanil was administered by TCI at a concentration for 4 min, and then propofol was given by TCI at a target effect-site concentration of 4 μg/ml.When the patients lost consciousness(bispectral index value<60)and the corresponding target effect-site concentrations of two drugs were achieved, SLIPA was inserted.Using the up-and-down sequential trial, the target effect-site concentration of sufentanil was determined according to patient′s responses to SLIPA insertion.The initial target effect-site concentration of sufentanil was 0.3 ng/ml, and the ratio between the two successive concentrations was 1.1.The EC50 and 95% confidence interval of sufentanil inhibiting responses to SLIPA insertion were calculated by using Dixon-Mood formula. Results The EC50 of sufentanil inhibiting responses to SLIPA insertion was 0.17 ng/ml, and the 95% confidence interval was 0.15-0.19 ng/ml. Conclusion When combined with propofol(target effect-site concentration 4 μg/ml)given by TCI, the EC50 of sufentanil inhibiting responses to SLIPA insertion is 0.17 ng/ml. Key words: Sufentanil; Propofol; Laryngeal masks; Dose-response relationship, drug; Drug delivery systems