Anaesthesia
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In this article we will look at some of the principles in processed EEG monitoring as applied to bispectral index (BIS). We outline why BIS should be regarded as a 'memory' monitor which in most circumstances reflects the depth of sedation or anaesthesia in particular patients. Its limitation in paralysed and non-paralysed patients must be understood in order for this monitor to be used safely. Finally, its emerging use in critical care will be explored.