Mivacurium for rapid tracheal intubation: the timing principle

ABSTRACT

BACKGROUND: The timing principle entails administration of a single bolus of non-depolarizing muscle relaxant, followed by an induction agent at the onset of neuromuscular blockade. Three different mivacurium dose regimens were compared to determine its safety and efficacy for rapid tracheal intubation in Filipinos METHODS: Sixty ASA I or II patients, 20-65 years old, surgery requiring orotracheal intubation were randomly allocated into three groups. Group I received 0.20 mg/kg, Group II 0.25 mg/kg, and Group III 0.30 mg/kg mivacurium over for twenty seconds. At the onset of 3-5 percent change in TOF, considered as the onset time, anesthesia was induced with thiopental at 5 mg/kg; laryngoscopy was accomplished at 95 percent neuromuscular blockade. Intubating conditions were assessed according to the Copenhagen Consensus Conference CCC rating scale RESULTS: The mean onset times for Groups I to III were 64.5 +/- 16.6 seconds, 47.5 +/- 10.8 seconds and 21.5 +/- 7.96 respectively, while the time to 95 percent blocks were 85.5 +/- 30.7 seconds, 57.8 +/- 9.8 seconds, and 35.0 +/- 9.9 seconds. Intubating conditions were either good or excellent in all patients. All patients were satisfied with the manner of induction of anesthesia CONCLUSION: Mivacurium at a dose of 0.3 mg/kg using the timing principle consistently provided good to excellent intubating conditions, 35-45 seconds after induction of anesthesia and is an acceptable alternative to succinylcholine for rapid tracheal intubation. (Author)