Speed and ease of tracheal intubation: priming with mivacurium compared with succinylcholine

This study examined the efficacy of mivacurium priming (0.015 mg · kg^?1) with five minutes between the priming and intubating doses by comparing the effects of one, two and three times the ED₉₅ dose (0.075 mg · kg^?1) of mivacurium after priming (Groups 1, 2 and 3, respectively), with a saline prime and 2 × ED₉₅ mivacurium (Group 4) or 1 mg · kg^?1 dose of succinylcholine (Group 5). The time from the intubating dose injection to intubation was measured and intubating conditions were rated on a five-point scale with 4 being optimal and 0 being failure. Mean times (± SEM) in seconds between the administration of the intubating dose and tracheal intubation were: 106.4 ± 5.1, 89.6 ± 6.7, 81.9 ± 2.7, 169.9 ± 7.8 and 82.9 ± 3.5 for Groups 1–5 respectively. The times for Group 2 (2 × ED₉₅ with priming), Group 3 (3 × ED₉₅ with priming) and Group 5 (succinylcholine with saline) were shorter than the times of Groups 1 (1 × ED₉₅ with priming) and 4 (2 × ED₉₅ with saline) P < 0.05. Mean intubating condition scores (± SD) for the five groups respectively were 3.1 ± 0.6, 3.4 ± 0.6, 3.5 ± 0.5, 3.2 ± 0.6 and 3.8 ± 0.4. Scores for Groups 2, 3 and 5 were higher than those of Group 1 (P < 0.05). The data demonstrated that (1) priming with mivacurium shortens the intubation time and is accompanied by good intubating conditions with doses 2× and 3× ED₉₅, and (2) intubating times and conditions similar to those achieved with succinylcholine can be obtained using mivacurium 2× (total dose 0.150 mg · kg^?1) or3 × ED₉₅ (total dose 0.215 mg · kg^?1) with a five-minute priming interval. Priming provides an alternative technique in those clinical circumstances where succinylcholine is contraindicated.