A clinical comparison of diazepam and thiopentone as induction agents to general anaesthesia.

Two hundred patients undergoing cystoscopy, with or without retrograde pyelography, were studied. Half of the patients were induced with 2.5 per cent thiopentone intravenously, the remainder with diazepam. Diazepam was diluted in normal saline immediately prior to anaesthesia, and used as a 0.1 per cent solution in 50 patients. The remaining 50 patients were induced with 0.5 per cent diazepam intravenously. On arrival in the operating room, the patients were given atropine 0.4 mg. intravenously. No other premedicant drugs were administered, nor were the patients receiving medications for other reasons. When an increase in pulse rate occurred, the patients were induced intravenously with either diazepam or thiopentone. If a rise in pulse rate was not obtained, the patients were induced two minutes after the intravenous injection of the atropine. Maintenance of anaesthesia was with nitrous oxide (6 L./min.) and oxygen (3 L./min.) through a Magill circuit using a face mask. Halothane was added in sufficient concentration to achieve satisfactory general anaesthesia, and thereafter the patients were maintained in as light a plane as possible. An attempt was made to anticipate the end of surgery and to decrease the concentrations of inhalational