DIFFERENT PRIMING TECHNIQUES, INCLUDING MIVACURIUM, ACCELERATE THE ONSET OF ROCURONIUM

Different priming sequences of equipotent doses of rocuronium and miva curium on the onset of maximum neuromuscular block and intubating cond itions were compared with those obtained after succinylcholine, During thiopentone-fentatanyl-nitrous oxide anaesthesia, 70 patients were ra ndomly assigned into seven groups. Group I received mivacurium 0.15 mg kg(-1) as a single bolus dose. Group II received a priming dose of mi vacurium 0.015 mg kg(-1) followed three minutes later by mivacurium 0. 135 mg.kg(-1). Group III received rocuronium 0.6 mg.kg(-1) as a single bolus dose, and Group IV received an initial dose of rocuronium 0.06 mg.kg(-1) followed by rocuronium 0.54 mg.kg(-1). Group V received a pr iming dose of mivacurium 0.015 mg.kg(-1) followed by rocuronium 0.54 m g.kg(-1) Group VI received an initial dose of rocuronium 0.06 mg.kg(-1 ) followed by mivacurium 0.135 mg.kg(-1) Group VII received succinylch oline 1.0 mg.kg(-1) Groups I; III, and VII received a placebo injectio n before the administration of the neuromuscular blocking drug. Additi onal thiopentone 2 mg.kg(-1) iv was given 30 sec before intubation. On set times (mean (95% confidence interval)) after priming a rocuronium block with either rocuronium (73 (57-90) sec) or mivacurium (58 (47-69 ) sec) were similar to those after succinylcholine (54 (40-68) sec), a nd were shorter (P < 0.01) than that observed in other groups. Intubat ing conditions were not different between the groups. The duration of neuromuscular block was shortest with succinylcholine. It is concluded that priming a rocuronium block with either mivacurium or rocuronium resulted in a neuromuscular block comparable to that of succinylcholin e in both the onset of action and intubating conditions.