Comparison of intubating conditions related to timed dosages and a nerve stimulator based on the measurement of acceleration using mivacurium.

A quantitative method of monitoring neuromuscular blockade has been recently introduced. It has been suggested, when using mivacurium, that a standardized passage of time be used for induction. The purpose of this study was to determine whether a difference existed in intubating conditions when using mivacurium between a timed-dose technique and the ParaGraph (Vital Signs, Inc., Totowa, New Jersey). In this prospective, experimental, clinical trial, 40 patients were randomized into two groups. Standardized induction sequences were used for both groups. A standardized rating tool was used to grade each intubation. Intubation commenced in the ParaGraph group when the monitor read one twitch. Intubation in the timed-dose group occurred 90 seconds after the first dose of mivacurium. The difference in intubating conditions score and time to intubation was tested by the Mann-Whitney-Wilcoxon lest. The ParaGraph group had superior intubating conditions when compared with the timed dose group (P = .0001). Of the ParaGraph group, 100% had good to excellent intubating conditions, and 85% of the timed-dose group had fair to excellent intubating conditions. Time to intubation was longer in the ParaGraph group, with a mean of 216 seconds compared with 121 seconds in the timed-dose group. The variable time to onset of mivacurium indicates that a timed-dose technique may yield less than optimal intubating conditions despite manufacturer recommendations.