Intramuscular rocuronium in infants and children: A multicenter study to evaluate tracheal intubating conditions, onset, and duration of action

Background: This multicenter, assessor-blinded, randomized study was done to confirm and extend a pilot study showing that intramuscular rocuronium can provide adequate tracheal intubating conditions in infants (2.5 min) and children (3 min) during halothane anesthesia. Methods: Thirty- eight infants (age range, 3-12 months) and 38 children (age range, 1 to 5 yr) classified as American Society of Anesthesiologists physical status 1 and 2 were evaluated at four investigational sites. Anesthesia was maintained with halo- thane and oxygen (1% end-tidal concentration if < 2.5 yr; 0.80% end- tidal concentration if > 2.5 yr) for 5 min. One half of the patients received 0.45 mg/kg intravenous rocuronium. The others received 1 mg/kg (infants) or 1.8 mg/kg (children) of intramuscular rocuronium into the deltoid muscle. Intubating conditions and mechanomyographic responses to ulnar nerve stimulation were assessed. Results: The conditions for tracheal intubation at 2.5 and 3 rain in infants and children, respectively, were inadequate in a high percentage of patients in the intramuscular group. Nine of 16 infants and 10 of 17 children had adequate or better intubating conditions at 3.5 and 4 min, respectively, after intramuscular rocuronium. Better-than-adequate intubating conditions were achieved in 14 of 15 infants and 16 of 17 children given intravenous rocuronium. Intramuscular rocuronium provided ≥ 98% blockade in 7.4 ± 3.4 min (in infants) and 8 ± 6.3 min (in children). Twenty-five percent recovery occurred in 79 ± 26 min (in infants) and in 86 ± 22 min (in children). Conclusions: Intramuscular rocuronium, in the doses and conditions tested, does not consistently provide satisfactory tracheal intubating conditions in infants and children and is not an adequate alternative to intramuscular succinylcholine when rapid intubation is necessary.