Design of an in-ear EEG device to detect consciousness levels and be used in monitoring anaesthesia levels of a patient in a medical setting

[摘要] ENGLISH ABSTRACT: There is, as of yet, no feasible and real-time monitor that can accurately determinethe level of conciousness experienced by a patient while under some form of general anaesthesia. Existing systems, such as the bispectral indexing (BIS) as well as expiratoryvapour measurement techniques such as minimum alveolar concentration (MAC), are both limited in accuracy and in usability. The existing methods use empirical, statisticaland historical means to derive at a consciousness indication, rather than a theoretical approach. A system that can accurately monitor levels of anaesthesia (or consciousness)is crucial for eliminating the health risks associated with the overdosing or underdosing of an anaesthetic.Auditory evoked potentials (AEPs) are the brain's electrical responses, measurable using an electroencephalography (EEG) set-up, to auditory stimulus. Such responsesgive an indication of the neurological pathway that an auditory signal takes from the eardrum to the processing thereof in the frontal cortex. It also provides an indication ofthe brains ability to process the information throughout the pathway. Changes in these responses, from a less-obtrusive in-ear electrode, could potentially be utilised to detectthe brain's consciousness of the auditory signal and, therefore, the overall consciousness of the patient.In the clinical trials completed, a characteristic peak latency, namely Pa, of the AEPs was compared to existing measures of anaesthesia and was shown to remarkably outperformthe BIS's ability to perceive consciousness. It also produced a more linear response than the commonly used expiratory values (being an indirect measure) and showed potentialfor better differentiating between all of the different levels of anaesthesia. The research completed could be instrumental in the development of a baseline consciousness monitorthat would be beneficial to the health and safety of anaesthetised patients worldwide.

[发布机构] Stellenbosch University