Efficacy and safety of divided dose administration of mivacurium for a 90-second tracheal intubation

Study Objective: To compare the safety and effectiveness of 0.25 mg divided doses of mivacurium chloride to succinylcholine for a 90-second tracheal intubation. Design: Randomized, double-blind, multicenter study in two groups. Setting: Operating rooms at four university medical centers. Patients: 200 healthy ASA status I and II adult patients scheduled for elective surgery with general anesthesia and endotracheal intubation. Interventions: Patients were premedicated with 1 to 2 mg midazolam and 2 mu g/kg fentanyl. Anesthesia was induced with 2 mg/kg propofol. Group A received 0.25 mg/kg mivacurium given as a divided dose (0.15 mg/kg followed in 30 seconds with 0.1 mg/kg). Group B (control) received 1.5 mg/kg succinylcholine (SCh) preceded two minutes earlier by 50 mu g/kg d-tubocurarine (dtc). Measurements and Main Results: Tracheal intubation grading, train-of-four response of the adductor pollicis, heart rate (HR) and mean arterial blood pressure (MAP) were measured and evaluated. Chi-square analysis was performed for comparison between Group A and Group B with respect to the frequency distribution of intubation using the scores excellent, good, and poor and not possible (combined). Group B had a significantly higher excellent score of intubation than Group A, 84% versus 56% (p < 0.001). No significant difference was found between the two groups when the scores excellent and good were combined (Fisher's Exact test, p = 0.28). The changes in MAP and HR were similar for the two groups. Conclusions: When Sch is not desirable, mivacurium 0.25 mg/kg given as a divided dose provides good to excellent intubation conditions 90 seconds after the initial dose without significant changes in MAP or HR. It can be an appropriate alternative for short surgical procedures. It must be emphasized that this conclusion does not apply to rapid-sequence induction-intubation.