[Effects of induction and supplementary doses of atracurium. Dose-response relationship, spontaneous reversion period, cardiovascular effect and clinical signs of histamine liberation].
The effects of an induction dose of atracurium 0.6 mg/kg and supplementary doses of 0.2 mg/kg and 0.1 mg/kg were investigated in 20 patients undergoing non-urgent laparotomy while anesthetized with halothane-N2O-O2. Atracurium was the only muscle relaxant used. Complete neuromuscular block was achieved in all patients, lasting an average of 37 min. Following a supplementary dose of 0.2 mg/kg or 0.1 mg/kg the neuromuscular block was extended on average for a further 25 min (range 13-37 min) or 15 min (range 5-30 min), respectively. The time to spontaneous reversion of complete neuromuscular block at TOF = 0.75 was 39 min (mean). Neither blood pressure nor pulse rate changed significantly following injection of the induction dose. In 3 patients (15%) there was a brief period of erythema with no simultaneous change in pulse rate or blood pressure after administration of the induction dose. The erythema did not recur in the same patients following the supplementary doses. Transitory rises in AST and LDH were noted in 1 patient.