title: Intramuscular rapacuronium in infants and children: dose-ranging and tracheal intubating conditions.
abstract: BACKGROUND
  Intravenous rapacuronium's rapid onset and short duration suggest that intramuscular rapacuronium might facilitate tracheal intubation without prolonged paralysis. Accordingly, the authors injected rapacuronium into the deltoid muscle to determine the optimal dose and time for intubation in pediatric patients.
  
  
  METHODS
  Unpremedicated patients (aged, 2 months to 3 yr) were studied. Part I: Spontaneous minute ventilation (V(E)) and twitch tension were measured during N2O/halothane anesthesia. Rapacuronium (2.2-5.5 mg/kg, given intramuscularly, n = 23), succinylcholine (4 mg/kg, given intramuscularly, n = 12), or vecuronium (0.1 mg/kg, given intravenously, n = 15) was given. Time to 50% depression of V(E) and 10% recovery of twitch were measured. Dose for each patient was changed 10-20% according to the previous patient's response. Part II: In 22 patients anesthetized with 0.82-1.0% halothane, the optimal rapacuronium dose determined in part I (infants, 2.8 mg/kg; children, 4.8 mg/kg) was given intramuscularly. Laryngoscopy was scored. Time to laryngoscopy was increased or decreased 0.5 min according to the previous patient's response.
  
  
  RESULTS
  Part I: Rapacuronium typically depressed ventilation in < or = 2 min with 10% twitch recovery in 20-60 min. With succinylcholine, median time to ventilatory depression was 1.3 and 1.1 min for infants and children, respectively; for vecuronium, 0.7 and 0.6 min. Part I: Intubating conditions were good-excellent at 3.0 and 2.5 min in infants and children, respectively; time to 10% twitch recovery (mean +/- SD) was 31 +/- 14 and 36 +/- 14 min in the two groups.
  
  
  CONCLUSIONS
  This pilot study indicates that deltoid injection of rapacuronium, 2.8 mg/kg in infants and 4.8 mg/kg in children, permits tracheal intubation within 2.5-3.0 min, despite a light plane of anesthesia. Duration of action is intermediate.
authors.affiliation: Department of Anesthesia and Perioperative Care, University of California, San Francisco 94143-0648, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Reynolds
authors.forename: A
authors.initials: A
authors.lastname: Infosino
authors.forename: R
authors.initials: R
authors.lastname: Brown
authors.forename: J
authors.initials: J
authors.lastname: Hsu
authors.forename: D M
authors.initials: DM
authors.lastname: Fisher
mesh_terms: D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007273:Injections, Intramuscular; D007275:Injections, Intravenous; D007442:Intubation, Intratracheal; D007828:Laryngoscopy; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009467:Neuromuscular Depolarizing Agents; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage / Q000009:adverse effects; D010865:Pilot Projects; D015656:Respiratory Mechanics / Q000187:drug effects; D013390:Succinylcholine; D013997:Time Factors; D014673:Vecuronium Bromide / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*
chemical_list: D009467:Neuromuscular Depolarizing Agents; D003473:Neuromuscular Nondepolarizing Agents; D014673:Vecuronium Bromide; C082938:rapacuronium; D013390:Succinylcholine