COMPARISON OF THE NEUROMUSCULAR EFFECTS OF MIVACURIUM AND SUXAMETHONIUM IN INFANTS AND CHILDREN

We compared both the time course of neuromuscular blockade and the car diovascular side-effects of suxamethonium and mivacurium during haloth ane and nitrous oxide anaesthesia in infants 2-12 months and children 1-12 years of age. Equipotent doses of mivacurium and suxamethonium we re studied; 2.2 X ED(95) was used in four groups of infants and childr en, while 3.4 X ED(95) was used in two groups of children. Onset of ne uromuscular block in infants was not significantly faster with suxamet honium than with mivacurium (P = 0.2). In all infants given suxamethon ium, intubating conditions were excellent, while, in 6/10 infants give n mivacurium, intubating conditions were excellent. Onset of complete neuromuscular block in children was significantly faster with suxameth onium, 0.9 min compared with mivacurium, 1.4 min (P less than or equal to 0.05). Increasing the dose of suxamethonium or mivacurium in child ren to 3.4 X ED(95) did not change the onset of neuromuscular block. R ecovery of neuromuscular transmission to 25% of initial twitch height (T-25) in infants and children was significantly faster after suxameth onium than after mivacurium, at 2.5 and 6 min, respectively (P less th an or equal to 0.05). In children given 3.4 X ED(95) of suxamethonium or mivacurium, recovery from neuromuscular block was almost identical with the dose of 2.2 X ED(95), with spontaneous recovery to T-25 prolo nged by only 0.5 min. No infant or child had hypotension after the miv acurium bolus dose.