Haemodynamic responses and prolongation of QT interval of ECG after suxamethonium-facilitated intubation during anaesthetic induction in children: a dose-related attenuation by alfentanil.

The haemodynamic response to endotracheal intubation and changes in the QT interval of ECG during anaesthetic induction were studied in 68 healthy children (5.5 years). The children were pretreated double-blindly with either alfentanil 10 micrograms/kg (A10), 25 micrograms/kg (A25), 50 micrograms/kg (A50) or saline (control) (17 children in each group) i.v. 1 min before thiopentone 5 mg/kg. The trachea was intubated after suxamethonium 1.5 mg/kg. Central nervous system excitation was seen in four of 17 and in one of 17 children after alfentanil 50 and 25 micrograms/kg, respectively. After intubation, heart rate increased significantly in the control group, remained at initial levels in the A10 and A25 groups and decreased in the A50 group. A pressor response to intubation was seen in the control and A10 groups. The QT interval was significantly prolonged after suxamethonium in the control and A10 groups, but remained at baseline levels in the A25 and A50 groups. Ventricular ectopic beats were only seen in 2/17 children in the control group. In conclusion, alfentanil 25 microgram/kg is ideal for preventing the haemodynamic response to endotracheal intubation and prolongation of the QT interval, a sign of sympathoadrenal activation, before induction of intravenous anaesthesia in children.