Pharmacodynamics and intubating conditions of cisatracurium in children during halothane and opioid anesthesia

Study Objectives: To determine the pharmacodynamics and intubating conditio ns of cisatracurium 0.2 mg/kg in children aged 2 to 12 years. Design: Open-label, randomized study. Setting: Operating room of a universi ty-affiliated hospital. Patients: 42 ASA physical status I and II patients, 24 to 155 months of age . Interventions: Patients were assigned to one of two groups: halothane anest hesia (G1) and opioid anesthesia (G2). Subsequently, each group was divided into two age subgroups: 24-59 months and 60-155 months. All patients were premedicated with midazolam intranasal 0.1 to 0.2 mg/kg. IN G1, anesthesia was induced with halothane up to 3% and N2O/O-2 (60-70/30-40%). Halothane w as reduced to less than or equal to 2%, 2 minutes before cisatracurium was administered. In G2, anesthesia was induced with fentanyl 2 mu g/kg and thi opental 5 mg/kg. Anesthesia was maintained with halothane 0.8-1.5% in N2O/( 2) in G1, and it was maintained with fentanyl, thiopental, and N2O/O-2 in G 2. Electromyography (EMG) assessed the neuromuscular function of the adduct or pollicis every 10 seconds with single-twitch supramaximal stimulus at in duction and train-of-four at recovery. After obtaining EMG baseline, cisatr acurium was administered. Onset time, time to 90% block, percentage of maxi mal block, clinical duration, and intubating conditions were recorded. For statistical analysis, Chi-square test, analysis of variance, and Tukey's te st were used, with p-value less than 0.05. Measurements and Main Results: Only first twitch (T-1) recovery to 25% was significantly longer in patients ages 24 to 59 months who received halothan e-based anesthesia, compared with those who received opioid-based anesthesi a (p < 0.05). Onset time, maximum block, and intubating conditions conditio ns did not differ between groups (p > 0.05). Conclusions: Cisatracurium 0.2 mg/kg offered acceptable intubating conditio ns at 90 seconds in 98% of pediatric patients, regardless of the anesthesia -based technique. Longer clinical duration in the halothane group in younge r children may be due to age-related potentiation or to the small number of patients enrolled in the younger subgroup. (C) 2000 by Elsevier Science In c.