Editorial I Is there any alternative to the

Bispectral Index Monitor? The importance of having a reliable indicator of depth of anaesthesia has long been realized by anaesthetists.1 Initially, the haemodynamic response to laryngoscopy, tracheal intubation and/or skin incision was used to assess the anaesthetic depth. Subsequently, electroencephalogra-phy (EEG) and the various forms of processed EEG (e.g. spectral edge frequency and total power) were used, none of which was very successful. In 1997, Aspect Medical Systems (Natick, MA, USA) introduced a device that displays a single `bispectral index ' or a BIS value, which measures the depth of anaesthesia. Over the years, the usefulness of the BIS monitor in having a high probability of correctly predicting the absence of consciousness during general anaesthesia has been recognized.2±4 Although ther