Journal: Can J Anesth 54(7):538-543, 2007. 23 References
Reprint: Dept 1 of Anesthesiology, Bozen Central Hospital, Lorenz Böhler Strasse 5, I – 39100 Bozen, Italy (M Bock, MD, DEAA)
Faculty Disclosure: Abstracted by L. Easley, who has nothing to disclose.
The results of studies evaluating the priming technique with rocuronium are conflicting. This randomized controlled trial was conducted to test the hypothesis that when using a modified priming technique, a smaller cumulative dose of rocuronium might result in a comparable onset of neuromuscular block as a large single dose of rocuronium in children. ASA PS 1 or 2 children, 1-7 years of age, undergoing elective surgical procedures were enrolled in this prospective randomized, double-blind study. The patients were randomly allocated by a computer-generated randomization schedule into one of four groups to receive rocuronium doses equivalent to 1.5 x ED95 or 2.0 x ED95, with or without priming. Following loss of eyelash reflex, the study drug was given via a freely running intravenous infusion in two divided doses, 1 minute apart. Neuromuscular function was evaluated using acceleromyography.
Children in Groups 1 and 3 received a placebo priming injection with saline, followed 1 minute later by a single bolus (intubating) dose of rocuronium 0.45 mg/kg IV and 0.6 mg/kg IV, respectively. Children in Groups 2 and 4 received a subparalyzing dose of rocuronium 0.045 mg/kg IV and 0.06 mg/kg IV, respectively (priming dose), followed 1 minute later by rocuronium 0.405 mg/kg IV and 0.54 mg/kg IV (intubating dose), respectively. Rocuronium priming significantly accelerated the onset of rocuronium-induced neuromuscular block (Groups 2 and 4) when compared to placebo saline priming (Groups 1 and 3). Spontaneous recovery to a T4/T1 ratio = 0.9 was dose-dependent, but not influenced by the priming technique. Finally, intubating conditions were judged as good to excellent in all children, irrespective of the dose of rocuronium.
Priming enhanced the onset of rocuronium in a pediatric patient population. While a priming interval of 3 to 4 minutes has generally been considered appropriate, the authors chose a shorter priming interval for three reasons. First, rocuronium has a faster onset of action than other intermediate-duration neuromuscular blocking drugs. Second, the onset time of neuromuscular blocking drugs may be slightly accelerated in children because of their higher proportional cardiac outputs. Third, a pilot study was conducted which suggested that a 1-minute priming interval is optimal. When used for rapid sequence induction, rocuronium priming in children not only hastens onset, but also leads to faster recovery from neuromuscular block because a smaller dose of the neuromuscular blocking drug is needed to achieve a comparable response.
In conclusion, priming with rocuronium accelerates the onset of neuromuscular block in pediatric patients without prolonging recovery time. Due to the recognized side effects of priming with neuromuscular blocking drugs, the authors suggest that priming with rocuronium should be restricted to these situations.
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