Combinations of high-dose vecuronium and mivacurium provide similar paralysis and intubation conditions to succinylcholine in paediatric patients

This randomized blinded study tested the hypothesis that equipotent doses of vecuronium and mivacurium given in combination could achieve onset times to 90% neuromuscular block (B90) and intubation scores similar to succinylcholine. Thirty children were randomly assigned to one of three groups as follows. Group Sux received a single dose (1 mg·kg^-1) of succinylcholine followed by normal saline. Group V₁M₁ received 0.08 mg·kg^-1 of vecuronium followed by 0.1 mg·kg^-1 of mivacurium. Group V₂M₂ received 0.16 mg·kg^-1 of vecuronium followed by 0.2 mg·kg^-1 of mivacurium. Anaesthesia consisted of propofol, fentanyl, and nitrous oxide. Neuromuscular response was monitored by adductor pollicis electromyography (Datex NMT). Sixty s after administration of the first injection, the laryngoscopy began, with the anaesthesiologist scoring the ease of intubation on a four category scale as excellent, good, poor, or inadequate. Time from injection to B90 was 39 (2.6) s after succinylcholine, which was not significantly different from 48 (3.5) s after vecuronium 0.16 mg·kg^-1 and mivacurium 0.2 mg·kg^-1 (V₂M₂). Mean time to B90 for group V₁M₁ was 64 (4.7) s, which was significantly different from that in group Sux. The intubation score was 'excellent' for all patients in groups Sux and V₂M₂ and for only seven of ten patients in group V₁M₁. Only combination of vecuronium (0.16 mg·kg^-1) and mivacurium (0.2 mg·kg^-1) provided rapid onset of neuromuscular blockade and excellent intubating conditions comparable to succinylcholine 1 mg·kg^-1. This combination did result in prolonged recovery times.