Use of audio signals derived from electroencephalographic recordings as a novel 'depth of anaesthesia' monitor.

Awareness under anaesthesia is an uncommon but serious phenomenon, which continues to occur despite the use of commercially available depth-of-anaesthesia (DOA) monitors. Many of these monitors use processed electroencephalographic (EEG) data to give an indication of anaesthetic depth. They all suffer from error due to electrical interference, individual variation and the inevitable inaccuracy inherent in the rendering of complex waveforms into a simplified digital score. It is recognised that, in the processing of complex analogue audio waveforms (i.e. sound), the human ear consistently outperforms the computer. I hypothesise that an audio signal derived from the raw EEG waveform could form the basis of a DOA monitor, enabling humans to directly determine whether a patient is awake or anaesthetised from sound alone. I propose to call the sounds derived from amplification of the EEG trace the 'audio EEG'.