A priming dose of rocuronium can shorten the onset time of neuromuscular blockade. The purpose of this study was to evaluate the effect of priming with rocuronium on the onset time and intubation conditions during tracheal intubation with low-dose rocuronium (0.35 mg/kg) and to compare results with those for rocuronium 0.45 mg/kg.

One hundred twenty four patients were randomly allocated to three groups. Following induction of anesthesia, groups I and III received normal saline while group II received a priming dose of rocuronium (0.05 mg/kg). Three minutes after priming, groups I, II and III received, respectively, 0.45 mg/kg, 0.3 mg/kg and 0.35 mg/kg rocuronium. Intubation was performed 2 minutes after the administration of an intubating dose and intubation conditions were evaluated. Neuromuscular blockade was assessed by accelerography.

The proportion of cases having optimal intubation conditions in group I was higher than in groups II and III. There was no significant difference in the onset times among groups. Neuromuscular blockade at 60, 90 and 120 seconds after an intubating dose was similar among all groups except at 60 sec. Maximal blockade for group I was deep compared to groups II and III.

Rocuronium 0.35 mg/kg does not provide satisfactory intubation conditions. There are no effects on onset time and intubation conditions due to priming during tracheal intubation with rocuronium 0.35 mg/kg.