Responsiveness of the frontal EMG for monitoring the sedation state of critically ill patients

Walsh, Timothy S; Lapinlampi, T P; Ramsay, Pamela; S�rkel�, M O K; Uutelo, K; Vierti�-Oja, H E

Abstract

Background. Excessive sedation is associated with adverse patient outcomes during critical illness, and a validated monitoring technology could improve care. We developed a novel method, the responsiveness index (RI) of the frontal EMG. We compared RI data with Ramsay clinical sedation assessments in general and cardiac intensive care unit (ICU) patients.
Methods. We developed the algorithm by iterative analysis of detailed observational data in 30 medical–surgical ICU patients and described its performance in this cohort and 15 patients recovering from scheduled cardiac surgery. Continuous EMG data were collected via frontal electrodes and RI data compared with modified Ramsay sedation state assessments recorded regularly by a blinded trained observer. RI performance was compared with EntropyTM across Ramsay categories to assess validity.
Results. RI correlated well with the Ramsay category, especially for the cardiac surgery cohort (general ICU patients r¼0.55; cardiac surgery patients r¼0.85, both P,0.0001).
Discrimination across all Ramsay categories was reasonable in the general ICU patient cohort [PK¼0.74 (SEM 0.02)] and excellent in the cardiac surgery cohort [PK¼0.92 (0.02)]. Discrimination between ‘lighter’ vs ‘deeper’ (Ramsay 1–3 vs 4–6) was good for general ICU patients [PK¼0.80 (0.02)] and excellent for cardiac surgery patients [PK¼0.96 (0.02)].
Performance was significantly better than EntropyTM. Examination of individual cases suggested good face validity.
Conclusions. RI of the frontal EMG has promise as a continuous sedation state monitor in critically ill patients. Further investigation to determine its utility in ICU decision-making is warranted.

Citation

Walsh, T. S., Lapinlampi, T. P., Ramsay, P., Särkelä, M. O. K., Uutelo, K., & Viertiö-Oja, H. E. (2011). Responsiveness of the frontal EMG for monitoring the sedation state of critically ill patients. British Journal of Anaesthesia, 107, 710-718. https://doi.org/10.1093/bja/aer228

• Journal Article Type: Article
• Acceptance Date: Jun 18, 2011
• Online Publication Date: Jul 28, 2011
• Publication Date: Jul 28, 2011
• Deposit Date: Jun 29, 2016
• Print ISSN: 0007-0912
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 107
• Pages: 710-718
• DOI: https://doi.org/10.1093/bja/aer228
• Keywords: critical care; diagnostic techniques; neurological; electroencephalogram; monitoring; physiologic; sedation; deep
• Public URL: http://researchrepository.napier.ac.uk/id/eprint/10392
• Publisher URL: http://dx.doi.org/10.1093/bja/aer228