SYNERGISM BETWEEN ATRACURIUM AND VECURONIUM IN CHILDREN

In 30 children under balanced anaesthesia, we have determined dose-res ponse curves and maintenance requirement of three dose ratio combinati ons of atracurium and vecuronium (10:1, 4:1 or 1.6:1 on a mug:mug basi s). Neuromuscular block was monitored by adductor pollicis EMG. An equ ipotent dose ratio (4:1) was most potent, with a mean (SEM) ED95 of at racurium 95(6) mug kg-1 with vecuronium 24 (1) mug kg-1. The sum of th ese doses is only 58% of an ED95 value of one agent (P=0.0001). The ho urly requirement to maintain a 90-95% neuromuscular block was 2.0 (0.1 ) times an individual ED95 dose of any combination. Recovery index was 8.9 (0.5) min. These results indicate that a combination of atracuriu m and vecuronium is supra-additive compared with the effects of each d rug alone. However, all combinations maintained an intermediate charac ter of neuromuscular block. Combining atracurium with vecuronium may r educe drug requirement by 40%.