Auditory evoked potentials for monitoring during anaesthesia: a study of data quality


Notley, S.V., Bell, S.L. and Smith, D.C. (2010) Auditory evoked potentials for monitoring during anaesthesia: a study of data quality. Medical Engineering and Physics, 32, (2), 168-173. (doi:10.1016/j.medengphy.2009.11.006).

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Description/Abstract

The auditory evoked potential termed the middle latency response (MLR) has been suggested as an indicator of adequacy of anaesthesia during surgery. However, the response is small and must be extracted from high levels of background noise. A key consideration in using the MLR for clinical monitoring is whether data quality is sufficient to detect small changes. The aim of this study was to investigate the quality of the MLR recorded during anaesthesia, as a rigorous analysis of data quality is lacking in many studies. MLR recordings from patients sedated in intensive care after cardiac surgery were compared to recordings from a reference group of young volunteers with normal hearing. Data quality was measured with the Fsp parameter. A bootstrap analysis was used to measure statistical response presence and to detect within-subject changes during clinical anaesthesia. Noise levels were high in the normative group probably due to myogenic and EEG activity. With 5 Hz click stimulation, MLR presence in the normative group was below 30%. Response presence improved using stimulation paradigms with chirps or maximum length sequences and reached 100% with a combination of maximum length sequences and chirps. Fsp values generally improved during anaesthesia as noise levels reduced and MLR presence was 100% for MLS click stimulation. Changes in the MLR amplitude with propofol infusion rate were small. Some within-subject changes in MLR amplitude were detected using the bootstrap analysis, but 100% detection was not possible. Conclusion: Obtaining good quality MLR data in awake subjects is challenging. Data quality improves during clinical anaesthesia and with advanced stimulation methods, but reliable detection of changes in the MLR for clinical monitoring remains a challenge.

Item Type: Article
ISSNs: 1350-4533 (print)
Keywords: anaesthesia, auditory evoked potentials, depth of anaesthesia, middle latency response, quality
Subjects: R Medicine > R Medicine (General)
R Medicine > RF Otorhinolaryngology
Divisions: University Structure - Pre August 2011 > Institute of Sound and Vibration Research > Human Sciences
ePrint ID: 145259
Date Deposited: 16 Apr 2010 15:07
Last Modified: 28 Mar 2014 15:16
Research Funder: EPSRC
Projects:
Developing a clinical indicator of depth of anaesthesia based on auditory evoked potentials
Funded by: EPSRC (EP/D505593/1)
Led by: Steven Bell
1 February 2006 to 31 January 2009
URI: http://eprints.soton.ac.uk/id/eprint/145259

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