Target concentration of propofol required to insert the laryngeal mask airway in children

Background: The aim of this prospective study was to determine the target concentration (C-PRED) curves for laryngeal mask airway (LMA(TM)) insertion in children. Methods: The C-PRED of propofol required for insertion of the LMA was determined in 72 unpremedicated children, aged 3-10 years, ASA physical status I. C-PRED was reached in 2 min according to a sequential allocation. LMA insertion was then performed by an experienced anaesthetist who was unaware of the concentration. Insertion conditions were noted as satisfactory (jaw relaxed, no coughing, gagging, swallowing or laryngeal spasm, minimal limb movement), excellent (no movement at all) or unacceptable if otherwise. Results: The C-PRED50 and C-PRED90 were 7.86 mug.ml(-l) [95% confidence interval (CI) 6.46-9.26] and 10.71 mug.ml(-l) (95% CI 9.31-12.12), respectively, in the satisfactory group and 10.86 mug.ml(-l) (95% CI 10.14-11.57) and 13.71 mug.ml(-l) (95% CI 12.99-14.42) in the excellent group when calculations were based on Kataria's pharmacokinetics. These figures were increased 1.5-fold when calculations were based on Marsh's pharmacokinetics. With Schuttler's pharmacokinetics, C-PRED50 were 4.62 mug.ml(-l) and 13.66 mug.ml(-l) for satisfactory and excellent groups, respectively. Conclusions: The target-controlled infusion technique for anaesthesia induction and insertion of the LMA was a safe and effective technique in our study.