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Interaction of vecuronium and atracurium during halothane anaesthesia in children
M H Sloan1, B Bissonnette, J Lerman
1Department of Anaesthesia, Hospital for Sick Children, University of Toronto, Ontario, Canada.
Insights
This study found that combining vecuronium and atracurium in children undergoing anesthesia did not produce additive or synergistic neuromuscular blockade effects. The combination did not alter recovery times compared to atracurium alone.
Area of Science:
- Anesthesiology
- Pharmacology
- Neuromuscular Blockade
Background:
- Vecuronium and atracurium are neuromuscular blocking agents used in anesthesia.
- Understanding their combined effects is crucial for safe pediatric anesthesia.
Purpose of the Study:
- To determine the dose-response relationships of vecuronium and atracurium in children.
- To evaluate the neuromuscular effects of combining vecuronium and atracurium.
Main Methods:
- Dose-response curves were established for vecuronium and atracurium in pediatric patients (ASA I-II).
- Neuromuscular blockade was monitored using train-of-four stimulation of the adductor pollicis brevis muscle.
- Comparison of individual drugs versus a combination of equipotent doses (1x ED95 each).
Main Results:
- ED50 and ED95 values were determined for both agents (Vecuronium: 0.021/0.037 mg/kg; Atracurium: 0.11/0.30 mg/kg).
- Dose-response slopes differed significantly (p < 0.001).
- Vecuronium onset was slower and duration shorter than atracurium alone; no difference was observed between atracurium and the combination. Recovery index was similar across all groups.
Conclusions:
- The dose-response relationships for vecuronium and atracurium are not parallel in pediatric patients.
- The neuromuscular effects of vecuronium and atracurium are neither additive nor synergistic.
- Combining vecuronium with atracurium does not prolong recovery time in pediatric anesthesia.
Abstract:
The combination of vecuronium and atracurium was studied in 60 children of ASA physical status 1 or 2. In part I, the dose-response relationships were determined in 30 children who were randomly assigned to receive a single bolus of 0.02, 0.025 or 0.03 mg kg-1 of vecuronium or 0.075, 0.01 or 0.0125 mg.kg-1 of atracurium. The evoked electromyogram of the adductor pollicis brevis muscle to train-of-four stimulation was monitored. The speed of onset of the neuromuscular blockade was determined by a 95% depression of the train-of-four whereas the recovery index was established at 75% recovery of T1. In part II, 30 children were randomly assigned to receive 2 x ED95 of vecuronium, 2 x ED95 of atracurium, or a combination of 1 x ED95 of vecuronium + 1 x ED95 of atracurium. This study showed that the ED50 and ED95 for vecuronium were 0.021 mg.kg-1 and 0.037 mg.kg-1 and for atracurium 0.11 mg.kg-1 and 0.30 mg.kg-1, respectively. The slopes of the dose-response relationships were significantly different (p < 0.001). With vecuronium alone, the speed of onset of neuromuscular blockade was significantly slower (p < 0.001) and the duration of action less (p < 0.001) than that with atracurium alone or with the combination. There were no differences between atracurium and the combination of both medications. The recovery index was similar for all groups. We conclude that the dose-response relationships of vecuronium and atracurium in children undergoing halothane anaesthesia are not parallel and the neuromuscular effects of vecuronium and atracurium are neither additive nor synergistic. While vecuronium has a shorter duration of action than atracurium, this feature is not apparent when it is combined with atracurium in equipotent doses. Recovery is rapid and not prolonged when these two drugs are combined.