optimal effect-site concentration of sufentanil for laryngeal mask insertion during induction with target-controlled propofol infusion at 4.0 micro g/mL

ABSTRACT

The objective of this study is to determine the optimal effect-site concentration [Ce] of sufentanil for satisfactory insertion of laryngeal mask airway [LMA] when administered with a target-controlled infusion [TCI] of propofol at 4.0 microg/mL. A total of 25 adult patients scheduled for minor elective surgery were enrolled in this study. All patients received induction with a combination of propofol and sufentanil TCI. The TCI of sufentanil was started at a target Ce of 0.1 ng/mL. After equilibrium with the plasma concentration, the TCI of propofol was initiated, targeting a preset Ce of 4.0 microg/mL. After the loss of consciousness, LMA was inserted and assessed by an experienced Anesthesiologist. The Ce of sufentanil for the next patient was guided by modified Dixon's up-and-down method using 0.05 ng/mL as a step size. The Ce of sufentanil required for successful LMA insertion in 50% of adults [EC50] was determined by calculating the midpoint concentration of all independent pairs of patients after at least seven crossover points. The optimal Ce [EC50] of sufentanil for LMA insertion during propofol induction using target Ce of 4 microg/mL was 0.16 ng/mL [95% confidence interval [CI] = 0.12-0.20]. There was a significant reduction in propofol induced pain score P = 0.0275 and insignificant hemodynamic changes. Ce of sufentanil required for successful LMA insertion in 50% of patients [EC50] using propofol target Ce of 4.0 microg/mL was 0.16 ng/mL [95% CI = 0.12-0.20] with a significant reduction in the propofol induced pain and hemodynamic stability.