Objective To compare endotracheal intubation condition and hemodynamics during rapid sequence induction and intubation (RSII) with mivacurium in divided doses and rocuronium in routine dose, and to optimize the application of mivacurium in RSII regimen.

Methods A total of 158 patients receiving elective surgery in Zhongshan Hospital, Fudan University were randomized to mivacurium group (group M, n=79) or rocuronium group (group R, n=79). Anesthesia was induced with mivacurium 0.25 mg/kg in divided doses or rocuronium 0.9 mg/kg combined with propofol, lidocaine, remifentanil, and ephedrine. The primary outcome was the excellent tracheal intubation condition rate evaluated by Cooper's scale, and the excellent rate difference was compared with the non-inferior cut-off value (﹣10%). The secondary outcome were changes of mean arterial pressure (MAP) and heart rate (HR) before and 10 minutes after induction (T_0-10) and incidences of adverse events.

Results The difference of excellent tracheal intubation condition rate was﹣5.06% (94.94% vs 100%; one-sided 97.5% CI﹣9.96%-∞), the lower limit of CI was higher than the non-inferiority margin (﹣10%), which satisfied the non-inferiority hypothesis (P=0.024). The MAP at T₃ and the HR at T₁₀ in group M were significantly lower than those in group R (P < 0.05), but there was no significant difference in MAP and HR at other time points. Upper chest flushing occurred in 18 patients (22.8%) in group M, which was significantly higher than that in group R (22.5%, P < 0.001).

Conclusions The intubation condition under 0.25 mg/kg of mivacurium in divided doses in RSII regimen is not inferior to that under 0.9 mg/kg rocuronium, and can provide stable hemodynamic environment.