Potency of doxacurium in infants, children, and adolescents during N2O-O-2-alfentanil anesthesia

Study Objective: To evaluate neuromuscular potency of doxacurium during balanced anesthesia in pediatric patients. Design: Prospective, consecutive sample trial. Setting: Operating room at a university hospital. Patients: 15 infants (1 to 11 months), 20 children (3 to 10 years), and 20 adolescents (13 to 19 years). Interventions: Anesthesia was induced and maintained with thiopental, alfentanil, and nitrous oxide in oxygen. No volatile drugs were used at any time during the study. The neuromuscular function was recorded as adductor pollicis electromyography evoked by a train-of-four stimulation at 20-second intervals. A cumulative log-dose probit-response curve of doxacurium was established for every patient. Measurements and Main Results: ED(50) and ED(95) doses of doxacurium (14 mu g/kg and 25 mu g/kg in infants, 26 mu g/kg and 53 mu g/kg in children, and 20 mu g/kg and 41 mu/kg in adolescents, respectively) were smallest in infants and greatest in children (p < 0.05 between each pair of groups by analysis of variance and Scheffe's F-test). Conclusions: Potency of doxacurium was greatest in infants and least in children. We suggest that doxacurium can be administered safely in infants, and with dosages close to those reported in adults. Childrens's dose requirements was almost 50% greater than that of infants.