Rapid Tracheal Intubation with Rocuronium: A Probability Approach to Determining Dose

Background. Rapid tracheal intubation with rocuronium has not been studied using a probability-based approach. The authors aimed to predict doses of rocuronium giving 90% and 95% probability of intubation within 60 s and to estimate their durations of action. Metbods: After premedication with midazolam, 2 mg, anesthesia was induced in 80 subjects with fentanyl, 2 pg/kg, followed 3 min later by propofol, 2 mg/kg. Patients received randomly rocuronium, 0.0, 0.4, 0.8, or 1.2 mg/kg (n = 20/ dose). Laiyngoscopy began 40 s later, aiming for intubation at 60 s, and conditions were graded perfect, acceptable, or unacceptable, with the first two conditions being successful intubation. Anesthesia was maintained with isoflurane 0.51.0% (end-tidal) and fentanyl. Duration of action was time until reappearance of the first tactile train-of-four response. The dose versus fraction of patients with successful intubation was analyzed by logistic regression. Doses giving 90% and 95% (D,, and D,5) probability of successful intubation were calculated. Results: Intubation was successful in 7,11,18, and 19 patients in the 0.0, 0.4, 0.8, and 1.2 mg/kg groups, respectively. The D,, and D,, doses (95% confidence limits in parentheses) were 0.83 (0.59-1.03) and 1.04 (0.76-1.36) mg/kg, respectively. Estimated time until first tactile train-of-four response after D,, and D,, doses was 32 and 46 min, respectively. Conclusions: After induction with fentanyl and propofol, rocuronium, 1.04 mg/kg, gives 95% probability of successful intubation at 60 s. (