The cerebral function analysing monitor (CFAM). A new microprocessor-based device for the on-line analysis of the EEG and evoked potentials.

A description is given of a new microprocessor-based device for EEG analysis. The Cerebral Function Analysing Monitor (CFAM) analyses the EEG amplitude and frequency distribution. It produces a detailed plot of amplitude trends and separate traces of the percentage activity in each of the classical EEG frequency bands. Its clinical application was studied in five patients anaesthetized with thiopentone, and nitrous oxide and halothane in oxygen. During maintenance of anaesthesia, there was a gradual decrease in EEG amplitude and shift towards lower frequency EEG activity. Discontinuation of nitrous oxide resulted in a marked increase in EEG amplitude and an increase in alpha and beta band activity. Discontinuation of halothane resulted in smaller alterations in the CFAM trace. This device provides easily interpreted processed EEG data and merits further investigation.