The influence of isoflurane on a continuous infusion of mivacurium

Abstract

Sixty surgical patients were studied to evaluate the neuromuscular effects of mivacurium 0.l5 mg.kg‐1 (2 × ED95)for tracheal intubation. After intubation the patients were randomly allocated to receive alfentanil with either propofol (starting with 9mg.kg‐1 h‐1, reducing to 6mg.kg‐1 h‐1 after 20min) or isoflurane (0.5% end‐tidal). In addition, all the patients were given a continuous infusion of mivacurium 10 μg.kg‐1 min‐1 after tracheal intubation which was adjusted to maintain 90% depression of T1. Following mivacurium 0.15 mg.kg‐1 T1 decreased below 25% in all but four patients. Mean (SD) percentage maximum block attainedwas 92.9% (12.5) after 309 (89)s. Tracheal intubation was completed 232 (155) s after administration of the relaxant and intubating conditions were graded as‘excellent’ or‘good’ in 56 patients. Although the mean (SD) mivacurium infusion rate for maintaining T1 at 10% was higher in the propofol group, 4.8 (2.1) compared with 4.4 (2.0) μg.kg‐1 min‐1 in the isoflurane group, this was not significantly different (p > 0.05). The mean (SD) recovery index was prolonged in the isoflurane patients, 757 (508)s, compared to those receiving propofol, 466 (219)s (p < 0.05). Copyright © 1995, Wiley Blackwell. All rights reserved