ED50 of oxycodone inhibiting responses to endotracheal intubation together with target concentration infusion of propofol / 临床麻醉学杂志

ABSTRACT

Objective To determine ED50 and ED95 of oxycodone inhibiting responses to endotracheal intubation together with target concentration infusion of propofol.Methods ASA physical status Ⅰ or Ⅱ patients,aged 18-65 years,with body mass index 18.5-24.9 kg/m2,falling into Mallampati Score Ⅰ or Ⅱ,undergoing elective surgery under general anesthesia,were enrolled.Anesthesia was induced with intravenous injection of oxycodone,target concentration infusion of propofol with plasma concentration of 4μg/ml and intravenous injection of rocuronium 0.9 mg/kg when BIS＜60.The patients were endotracheally intubated and mechanically ventilated.The initial dose of oxycodone was 0.2 mg/kg.The dose of oxycodone was increased/decreased by ratio of 1.1 in the next patient by modified Dixon's up-and-down method.The response to endotracheal intubation was defined as an increase in the maximum mean arterial pressure and/or the maxmium heart rate≥20％ of the baseline value with 2 minute after intubatior.Probit analysis was used for calculating ED50,ED95 and 95％ confidence interval (CI) of oxycodone inhibiting responses to endotracheal intubation.Results There were twenty-seven patients who completed the test finally.ED50 and ED95 (95％ CI)of oxycodone inhibiting responses to endotracheal intubation were respectively 0.204 (0.175-0.249)mg/kg and 0.342(0.287-0.409) mg/kg.Conclusion When plasma target concentration of propofol 4 μg/ml is infused,ED50 and ED95 of oxycodone inhibiting responses to endotracheal intubation is 0.204 and 0.342 mg/kg,respectively.