Dose of propofol for laryngeal mask airway insertion in children: Effect of premedication with midazolam

We determined the dose-response curves and effective doses of propofol for insertion of the laryngeal mask airway (LMA) in 50 unpremedicated children and in 60 children premedicated with midazolam, aged 3-12 yr. One of several doses of propofol was administered i.v. over 15 s to groups of 10 children, and conditions for LMA insertion were assessed at 60 s. The dose-response curves were parallel (P = 0.94), but the curve for premedicated children was shifted significantly to the left of that for unpremedicated children and propofol requirements were reduced by one-third (P < 0.0001). The doses required for satisfactory LMA insertion in 50% and 90% of unpremedicated patients (ED(50), ED(90)) (95% confidence interval) were 3.8 (3.4-4.2) mg kg(-1) and 5.4 (4.7-6.8) mg kg(-1), respectively; those for premedicated patients were 2.6 (2.2-2.8) mg kg(-1) and 3.6 (3.2-4.3) mg kg(-1), respectively.