Chlormethiazole (Heminevrin), pethidine and nitrous oxide as compared to halothane for general anesthesia

The anaesthetic and postanaesthetic course in a group of gynaecological patients anaesthetized with chlormethiazole (Heminevrin) was investigated and the results compared to a similar group of patients anaesthetized with halothane. Both drugs were used as the main anaesthetic agent in the respective regimes, supplemented by nitrous oxide/oxygen and muscle relaxants. Because chlormethiazole is devoid of analgetic effects, the importance of using pethidine in combination with chlormethiazole is emphasized. An advantage of using chlormethiazole is that it can serve as both an induction and maintenance agent. The plasma concentrations of chlormethiazole were studied in seven patients. For induction, the mean concentration was 4.5 micrograms/ml. The mean concentration on waking at the termination of operation was 1.3 micrograms/ml. No serious side effects were encountered in either treatment. The results suggested that chlormethiazole in combination with an analgetic drug and nitrous oxide could be suitable in elderly patients, although occasionally less effective in the young.