Early neuromuscular recovery characteristics following administration of mivacurium plus vecuronium

Abstract

Purpose: This study was designed to describe the early recovery characteristics, as well as the speed of onset of neuromuscular block, after a combination of mivacurium and vecuronium. Methods: In this controlled, randomized study, 30 consenting ASA I-III patients were assigned to three treatment groups. The '2M2V' group received twice the dose necessary to cause 95% depression of the evoked twitch response (2 x ED95) of mivacurium (0.15 mg · kg-1) plus 2 x ED95 of vecuronium (0.1 mg · kg-1); the '2V' group received 2 x ED95 of vecuronium; and the '4V' group received 4 x ED95 of vecuronium. Evoked neuromuscular responses of the adductor pollicis were assessed with an adductor pollicis force transducer. The time until maximum block and times to 10% and 25% recovery (T10 and T25) in each group were expressed as mean ± standard deviation and compared using ANOVA. Results: Onset of block in the 2M2V group was 27% faster than in the 2V group (2.0 ± 0.6 vs. 2.7 ± 0.8 min respectively, P < 0.05) and was similar to the 4V group (1.95 ± 0.3 min, P = NS). The times until 10% recovery were similar in the 2M2V and 4V groups (59.9 ± 12 vs 68.2 ± 25 min, P = NS) and were slower than in the 2V group (37.2 ± 9 min, P < 0.05). Between T10 and T25 recovery after 2M2V resembled that after 2V (6.7 ± 3 vs 5.7 ± min, P = NS) and was faster than after 4V (10.9 ± 7 min, P < 0.05). Conclusions. When 2 x ED95 of mivacurium is added to 2 x ED95 of an intermediate or long-acting relaxant, recovery after T10 will proceed as if one had administered the longer-acting agent alone.