The ideal anaesthetic depth is where the risk of operative recall or awareness is as low as possible, regardless of what is happening surgically, and where blood pressure and heart rate are kept optimal for the individual patient. BIS decreases as anaesthesia deepens and a value of 40-60 is typical during maintenance of anaesthesia. The combination of low blood pressure with low BIS, but low minimum alveolar concentration of volatile anaesthetics (deeper anaesthesia despite low anaesthetic concentration) has also been linked to excess early deaths.[9]. [Extracted from the article]