Intramuscular rapacuronium in infants and children - A comparative multicenter study to confirm the efficacy and safety of the age-related tracheal intubating doses of intramuscular rapacuronium (ORG 9487) in two groups of pediatric subjects

Background: This multicenter, assessor, blinded, randomized study was condu cted to confirm and extend a pilot study in which intramuscular rapacuroniu m was given to infants and children to confirm efficacy and to evaluate tra cheal intubating conditions. Methods: Ninety-six pediatric patients were studied in two groups: infants aged 1 to 12 months (n = 46) and children aged 1 to 3 yr (n = 50). Infants received 2.8 mg/kg and children 4.8 mg/kg of intramuscular rapacuronium dur ing 1 minimum alveolar concentration halothane anesthesia. These two groups were studied in three subgroups, depending on the time (1.5, 3, or 4 min) at which tracheal intubation was attempted after the administration of intr amuscular rapacuronium into the deltoid muscle. Neuromuscular data collecte d included onset time, duration of action, and recovery data during train-o f-four stimulation at 0.1 Hz. Data were analyzed by the Cochran-Mantel-Haen szel procedure. Results: The tracheal intubating conditions were deemed acceptable in 17, 3 6, and 64% of infants and 20, 47, and 71% of children at 1.5, 3, or 4 min, respectively. The mean values for % of control twitch height (T1) 2 min aft er rapacuronium in both groups were similar. The mean (SD) time required to achieve more than or equal to 95% twitch depression in infants was 6.0 (3. 7) versus 5.5 (3.8) min in children. Conclusions: Only 27% of patients achieved clinically acceptable tracheal i ntubating conditions at 1.5 or 3 min after administration of 2.8 mg/kg and 4.8 mg/kg rapacuronium during 1 minimum alveolar concentration halothane an esthesia. Tracheal intubation conditions at 4 min were acceptable in 69% of subjects. The duration of action of 4.8 mg/kg of rapacuronium in children was longer than 2.8 mg/kg of rapacuronium in infants.