E.C.G changes during halothane and enflurane anaesthesia for E.N.T. surgery in children.

E.c.g. changes were compared in 152 children undergoing adenoidectomy of adenotonsillectomy (T + A) under halothane or enflurane anaesthesia. Junctional rhythm occurred in 4-16% of the children in adenoidectomy groups and in 11-33% in T + A groups. Bundle branch block occurred in 4% of the children anaesthetized with halothane, but not with enflurane and was particularly common in association with thiopentone and T + A operations; one patient had bifocal ventricular tachycardia. QT interval was prolonged compared with control after thiopentone (P less than 0.001) and thiopentone and suxamethonium (P less than 0.02). QT interval was not changed after Althesin with or without suxamethonium. Mean preanaesthetic QT interval (+/- SEM) was significantly prolonged (492 +/- 22 ms; normal 440 ms) in children showing aberrant conduction with chaotic rhythm, but normal (438 +/- 5 ms) when bundle branch block or junctional rhythm was present during halothane anaesthesia. QT interval was prolonged significantly in enflurane but not in halothane anaesthesia.