A COMPARISON OF THE NEUROMUSCULAR AND CARDIOVASCULAR EFFECTS OF VECURONIUM, ATRACURIUM AND MIVACURIUM IN SHEEP

Neuromuscular and cardiovascular effects of vecuronium, atracurium and mivacurium were compared in 45 sheep. The onset and duration of neuro muscular block produced with loading doses of vecuronium (25 mu g kg(- 1)), atracurium (500 mu g kg(-1)) and mivacurium (200 mu g kg(-1)) and maintained with incremental doses (7, 170 and 70 mu g kg(-1), respect ively) were monitored using train-of-four stimulation of the it. facia lis-m. levator nasolabialis unit. The electrocardiogram; heart rate an d arterial blood pressure were recorded during onset of neuromuscular blockade. Mean loading dose onset times for atracurium (98 seconds) an d mivacurium (86 seconds) were significantly shorter than vecuronium ( 203 seconds). Vecuronium produced significantly longer block (40 minut es) than atracurium (28 minutes) and mivacurium (15 minutes). There wa s no evidence of drug cumulation with atracurium or mivacurium. Cardia c dysrrhythmias were not observed in any group. Atracurium and mivacur ium produced intermediate- and short-duration neuromuscular blockade, respectively. Vecuronium produced a prolonged effect after a slow onse t.