THE VALUE TO THE ANESTHETIST OF MONITORING CEREBRAL-ACTIVITY

The administration rate of general anaesthetic drugs is at present gui ded by clinical experience, and indirect indicators such as haemodynam ic parameters. In the presence of muscle relaxants most of the clinica l signs of inadequate anaesthesia are lost and accidental awareness ma y occur. A number of monitoring modalities, primarily based on analysi s of the electroencephalogram (EEG), have been proposed for measuremen t of the anaesthetic depth. Moreover intraoperative cerebral monitorin g may also provide the anaesthetist with early warning of cerebral isc haemia, or information on specific neurological pathways. To facilitat e this, it is essential to combine analysis of the spontaneous EEG wit h recording of evoked potentials, to assess both cortical and subcorti cal activity/events. None of the reviewed methods, however promising, can alone meet all of the requirements for intraoperative monitoring o f cerebral function. We suggest that the future direction should be to integrate several modalities in a single device, to provide valuable new information, upon which to base clinical management decisions.