BACKGROUND: The median effective concentration, EC(50), for the supraglottic airway (predicted plasma concentration equilibrated with the effect site at which supraglottic airway insertion is successful in 50% of patients) of propofol in children was not known. The aim of this study was to determine the EC(50) with a target-controlled infusion of propofol to insert a classic laryngeal mask airway (LMA) and laryngeal tube (LT) in pediatric patients.

METHODS: Pediatric patients scheduled for urologic, orthopedic, or plastic surgery lasting less than 2 hr under general anesthesia were enrolled in this study. The patients were divided into two groups in a randomized, double blind manner. After applying a standard cardiorespiratory monitor, anesthesia was carried out with a target-controlled infusion (TCI) using the stelpump program. The initial target concentration of propofol was 5µgram/ml, and in accordance with Dixon's up-and-down, the propofol concentration for consecutive patients in each group was varied with increments or decrements of 0.2µgram/ml based on the previous patient insertion result.

RESULTS: The EC₅₀ of propofol required to insert a LMA and LT was 5.5±0.2µgram/ml and 5.6±0.2µgram/ml, respectively.

CONCLUSIONS: The EC₅₀ of propofol is similar for LMA and LT.