Dose-effect relationship of remifentanil inhibiting responses to endotracheal intubation without neuromuscular relaxant when combined with dexmedetomidine in patients undergoing thyroid surgery / 中华麻醉学杂志

ABSTRACT

Objective:To determine the median effective dose (ED 50) and the 95% effective dose (ED 95) of remifentanil inhibiting responses to endotracheal intubation without neuromuscular relaxant when combined with dexmedetomidine in patients undergoing thyroid surgery. Methods:American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients of either sex, aged 18-64 yr, with body mass index of 18-28 kg/m 2, scheduled for elective thyroid surgery under intraoperative neuromonitoring, were enrolled in this study.Dexmedetomidine was intravenously injected in a loading dose of 0.8 μg/kg at 10 min before anesthesia induction.Anesthesia was induced by intravenously injecting midazolam 0.1 mg/kg, etomidate 0.4 mg/kg and the preset dose of remifentanil.The dose of remifentanil was determined using up-and-down sequential method.The initial dose was set at 3.7 μg/kg.The dose of remifentanil in the next case was determined according to whether responses to endotracheal intubation occurred, and the ratio between the two successive doses was 1.1.The ED 50, ED 95 and 95% confidence interval (CI) were calculated by Probit analysis. Results:when combined with dexmedetomidine for anesthesia induction, the ED 50 (95% CI) of remifentanil inhibiting responses to endotracheal intubation without neuromuscular relaxant was 3.39 (3.29-3.50) μg/kg, and the ED 95 (95% CI) was 3.52 (3.48-3.64) μg/kg. Conclusion:when combined with dexmedetomidine, the ED 50 of remifentanil inhibiting responses to endotracheal intubation without neuromuscular relaxant is 3.39 μg/kg, and the ED 95 is 3.52 μg/kg.