ABSTRACT
Depth of anaesthesia (DOA) monitoring can be used to reduce the risk of accidental awareness during general anaesthesia and to titrate the dose of anaesthetic agent used in order to minimise the adverse effects of excessively deep anaesthesia, which would also have cost-saving benefits. There is considerable heterogeneity and uncertainty between various studies using Electroencephalography-based monitors to determine DOA. This is mainly due to the individual response to anaesthesia, diverse case mix and the variation in administering anaesthesia in clinical practice. It is also not fully established how Electroencephalography DOA monitors perform when drugs such as ketamine or nitrous oxide are used in conjunction with propofol or inhalation anaesthetic agents. Electroencephalography-based DOA monitors use electrodes on the forehead to measure the Electroencephalography activity, which is then processed using various algorithms that are currently a commercial secret. Propofol, thiopentone and volatile anaesthetic agents all produce a similar pattern of Electroencephalography changes with increasing brain concentrations and corresponding DOA.
