Comparison of thiopentone, Althesin and ketamine in anaesthesia for otolaryngological surgery in children.

Thiopentone 4 mg/kg, Althesin 0.055 ml/kg and ketamine 2 mg/kg were compared in 157 children undergoing minor otolaryngological surgery, mostly adenotonsillectomy. Premedication was with pethidine and atropine and anaesthesia was maintained with nitrous oxide in oxygen and halothane. Tracheal intubation was facilitated with suxamethonium. In each group half of the children received pethidine 0.7 mg/kg after intubation and the remainder received saline. Ketamine increased arterial pressure after induction. The cardiovascular responses to intubation were more obvious after thiopentone and Althesin than after ketamine. Operating conditions, cardiovascular changes during operation and the course of extubation were similar in all groups. The recovery after ketamine was longer than after thiopentone and Althesin. Thiopentone was associated with significantly less vomiting immediately after operation than was Althesin and ketamine. In the period immediately after operation Althesin was associated with a higher need for analgesics compared with thiopentone and ketamine. Pethidine prolonged the recovery after thiopentone, decreased the incidence of vomiting immediately after operation associated with Althesin and increased that associated with ketamine.