Electroencephalogram depth of anaesthesia monitors are increasingly being used, with the aim of reducing awareness during anaesthesia. Most literature concentrates on the ability of these monitors to predict when a patient is likely to be aware. This case report highlights the opposite problem, where the monitor (M-Entropy™) indicated an awake state but the patient was in fact deeply anaesthetised. If the anaesthetist is unable to interpret the raw electroencephalogram and understand the limitations of the monitor being used, excessive doses of anaesthetic may be given with potentially serious consequences.
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