The effects of althesin on the electroencephalograph.

The EEG was continuously recorded on 43 patients who received Althesin. A basic pattern for this drug, typical of most general anaesthetic agents at a level of light surgical anaesthesia, was established. Four significant levels of change could be discriminated in the EEG following administration of incremental boluses of undiluted Althesin, reflecting deeper levels of anaesthesia. These ranged from a mild slowing of the dominant rhythms to burst-suppression activity at the deepest level reached with larger doses. The EEG demonstrated that althesin has a rapid onset and a short duration and that recovery is rapid and complete after continuous infusion.