Modification of chronotropic response to anticholinergics by halogenated anaesthetics in children.

Cardiac rate and rhythm changes were studied in 40 children after intravenous injection of atropine or glycopyrrolate following induction of anaesthesia with halothane and enflurane. Premedication was standardized in all groups and ventilation controlled to achieve normal end tidal carbon dioxide. Heart rate increased in all cases following anticholinergic medication and the increase in heart rate was significantly higher in children receiving halothane anaesthesia as compared to those given enflurane. There was no significant difference between atropine and glycopyrrolate groups. There was no difference in frequency of occurrence of junctional tachycardia, which was the only arrhythmia observed, in the four groups studied. Our findings suggest that, in clinical situations where development of marked tachycardia is a concern, the combination of enflurane and anticholinergic drugs offers an advantage over the combination of halothane and anticholinergic drugs in paediatric patients.