ED50 of remifentanil needed for tracheal intubation without neuromuscular relaxant in children when combined with sevoflurane inhalation

Abstract

Objective To determine the ED50 of remifentanil needed for tracheal intubation without neuromuscular relaxant in children when combined with sevoflurane inhalation.Methods Twenty-five ASA Ⅰ or Ⅱ children of both sexes,aged 4-9 yr,scheduled for elective surgery under general anesthesia were enrolled in this study.Anesthesia was induced with inhalation of 5% sevoflurane in 100% oxygen and PETCOM2was maintained at 30-35 mm Hg.Remifentanil was injected intravenously over 30 s after 3 min inhalation of sevoflurane.Tracheal intubation was performed 90 s after the completion of remifentanil injection.The experiment was performed using the modified Dixon's up-and-down method.The initial dose of remifentanil was set at 1.2 μg/kg and the ratio between two successive doses was 1.2.Intubation conditions were assessed by a blinded observer using Viby-Mogensen scale.If the conditions were not good,roenronium 0.3 mg/kg was then injected intravenously to facilitate intubation.The ED50 of remifentanil and 95% confidence interval (95% CI) were calculated.Results The ED50 of remifentanil combined with inhalation of scvoflurane required for successful intubation was 0.68 μg/kg in the absence of neuromuscular relaxant,and 95% CI was 0.65-0.71 μg/kg.Conclusion The ED50 of remifentanil required for tracheal intubatiun without neuromuscular relaxant drug is 0.68 μg/kg (95% CI 0.65-0.71 μg/kg) when combined with 5% sevoflurane inhalation in children. Key words: Piperidines; Anesthetics,inhalation; Intubation,intratracheal; Dose-response relationship,drug; Child