[Rapid sequence muscular relaxation: vecuronium versus succinylcholine]

Onset times and conditions of endotracheal intubation were compared in 340 patients. They were all classified ASA I or II and free from any condition which might interfere with the pharmacokinetics or pharmacodynamics of muscle relaxants. The patients were randomly assigned to 4 groups where different muscle relaxation techniques with vecuronium were used: "priming" group (n = 150, 10 micrograms.kg-1 followed by 100 micrograms.kg-1 4 min later), "high dose" group (n = 70, 250 micrograms.kg-1), "control" group (n = 60, 100 micrograms.kg-1) and "succinylcholine" group (n = 60, 1 mg.kg-1). All anaesthetic conditions were otherwise similar. Electromyographic monitoring of the hypothenar muscles displayed no impairment in the reaction to a train-of-four stimulus during the pre-relaxation period (4 min) in the "priming" group. No incident was observed in these patients. Ten % of control response were obtained in 61, 86, 135 and 210 s respectively, whereas maximum muscle blockade was obtained in 97, 174, 314 and 74 s respectively. Intubation scoring showed that optimum conditions were obtained when muscle responses were almost fully abolished. These data are in disagreement with those reports on the priming technique where intubation is carried out 60 s after administration of the relaxing dose.