Dose-effect relationship of alfentanil inhibiting cardiovascular responses to endotracheal intubation when combined with midazolam and etomidate / 中华麻醉学杂志

ABSTRACT

Objective:To investigate the dose-effect relationship of alfentanil inhibiting cardiovascular responses to tracheal intubation when combined with midazolam and etomidate.Methods:American Society of Anesthesiologists Physical Status classification Ⅰ or Ⅱ patients of either sex, aged 18-64 yr, with body mass index<32 kg/m 2, undergoing elective operation under general anesthesia with endotracheal intubation, were enrolled in this study.Midazolam 0.025 mg/kg was intravenously injected for adequate sedation, and 5 min later mean arterial pressure and heart rate were recorded for 3 consecutive times at an interval of 3 min, and the mean value was calculated and served as the baseline value.Etomidate 0.3 mg/kg was intravenously injected, and alfentanil and rocuronium 0.6 mg/kg were intravenously injected when bispectral index value < 60, and then 1.4 min later tracheal intubation was performed.The dose of alfentanil was determined by the Dixon′s up-and-down method.The initial dose of alfentanil was set at 20 μg/kg.The dose of alfentanil in the next patient was determined according to the development of cardiovascular responses to tracheal intubation, and the ratio between the two successive doses was 1.0∶1.1.The cardiovascular response was defined as as positive when the maximum value of mean arterial pressure or heart rate increased by ≥20% of the baseline value within 2 min after endotracheal intubation.Probit method was used to determine the ED 50, ED 95 and 95% confidence interval of alfentanil inhibiting cardiovascular responses to tracheal intubation. Results:When combined with midazolam and etomidate, the ED 50 (95% confidence interval) of alfentanil inhibiting cardiovascular responses to tracheal intubation was 21.343 (19.105-24.516) μg/kg, and the ED 95 (95% confidence interval) was 25.043 (22.983-48.983) μg/kg. Conclusions:When combined with midazolam and etomidate, the ED 50 and ED 95 of alfentanil inhibiting cardiovascular responses to tracheal intubation are 21.343 and 25.043 μg/kg, respectively.