Objective  To investigate the effect of age on median effective dose(ED₅₀)of rocuronium on tracheal intubation following anesthesia of propofol combined with etomidate.

  Methods  A total of 160 patients with elective operation under general anesthesia were selected as study objects, and were divided into group A(n=51, aged from 18 to 40 years), groups B(n=54, aged from 41 to 65 years) and group C(n=55, aged from 66 to 79 years) according different ages. The sequential method was conducted in three groups, with initial dosages of 0.348 mg/kg in the group A, 0.290 mg/kg in the group B and 0.242 mg/kg in the group C. The heart rate (HR), blood oxygen saturation (SpO₂), mean arterial pressure (MAP) at the time points of induced anesthesia (T₀), intubation (T₁), 1 min after intubation (T₂), 3 min after intubation (T₃) and extubation (T₄) were compared, tracheal intubation condition, induction time, onset time, and awakening time, pain scores and adverse reactions were recorded. Rocuronium ED₅₀ and 95% confidence interval (95%CI) were calculated.

  Results  There was no difference in tracheal intubation condition of three groups(P > 0.05). There were no differences in heart rate (HR) and SpO₂ of three groups at each time point(P > 0.05), while the levels of MAP of the group B and group C were higher than the group A at each time point(P < 0.05). Compared with the group A and the group B, the induction and onset time of the group C was shorter, while the recovery time was longer(P < 0.05). There were no significant differences in induction time, onset time and recovery time between the group A and the group B (P > 0.05). There was no statistical significance in the grading of pain degree after awakening among three groups (P > 0.05). The ED₅₀ of the group C was 0.267 mg/kg (95%CI, 0.223 to 0.320), which was significantly lower than 0.321 mg/kg (95%CI, 0.297 to 0.347) and 0.314 mg/kg (95%CI, 0.283 to 0.348) of the groups A and B(P < 0.05). There was no significant difference in ED₅₀ between the group A and the group B (P > 0.05). There were no significant difference of incidence of preoperative, intraoperative and postoperative adverse reactions of three groups (P > 0.05).

  Conclusion  Age is an important interfering factor on ED₅₀ of rocuronium on tracheal intubation following anesthesia of propofol combined with etomidate, the values of ED₅₀ for patients aged 18 to 40, 41 to 65 and 66 to 79 years are 0.321 mg/kg, 0.314 mg/kg and 0.267 mg/kg, respectively.