Clinical pharmacology of cisatracurium during nitrous oxide-propofol anesthesia in children

STUDY OBJECTIVE: To describe, in pediatric patients, the effects of three doses of cisatracurium during nitrous oxide-propofol anesthesia and to determine if larger doses result in faster onset time.

SETTING: College hospital.

SUBJECTS: 75 ASA physical status I and II children, aged 15 to 60 months, undergoing surgery for hypospadias or undescendent testis.

INTERVENTIONS: Patients were randomly assigned to one of three groups according to the dose of cisatracurium: Group A = 0.1 mg/kg (two x effective dose), Group B = 0.15 mg/kg (three x effective dose), and Group C = 0.2 mg/kg (4 x effective dose).

MEASUREMENTS: Neuromuscular block was assessed with TOF-Guard (Biometer International, Odense, Denmark) accelerometry. Onset time (from cisatracurium injection to maximal depression of time to first twitch), duration of peak effect (time from cisatracurium injection to 5% recovery of time to first twitch), duration of clinical action (time from cisatracurium injection to 25% recovery of time to first twitch), and recovery index (recovery of time to first twitch from 25% to 75%) were recorded.

MAIN RESULTS: Cisatracurium had no effect on heart rate or blood pressure at any dose. Compared with Group A, onset times in Groups B and C were shorter; and durations of peak effect and clinical action in Groups B and C were longer (P < 0.01) than those in Group A. There was no difference in recovery index among the three groups. There was no difference in onset times between Groups B and C. Compared with Group B, durations of peak effect and clinical action in Group C were longer (P < 0.05 or P < 0.01).

CONCLUSION: Four times the effective dose of cisatracurium did not significantly shorten onset time beyond that produced with three times the effective dose in young children.