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Measuring depth of sedation in intensive care patients with the electroencephalographic Narcotrend Index

Weber, F.*,a; Steinberger, M.; Ritzka, M.¶,a; Prasser, C.; Bein, T.

European Journal of Anaesthesiology (EJA): February 2008 - Volume 25 - Issue 2 - p 123–128
doi: 10.1017/S0265021507001329
Original Article

Background and objective: The electroencephalographic Narcotrend Index was evaluated as a measure of sedation in mechanically ventilated intensive care unit patients. Narcotrend Index and conventional electroencephalography parameter values were compared to the Richmond Agitation-Sedation Scale and a simplified three-level sedation scale.

Methods: In all, 100 mechanically ventilated patients, admitted to the cardiac surgical intensive care unit after open-heart surgery, were enrolled in this prospective observational study. The Narcotrend Index was recorded while patients were either sedated by propofol infusion or without sedative medication while being weaned off the ventilator. Clinical assessment of the patients' level of sedation was performed by means of the Richmond Agitation-Sedation Scale by a single observer who was blinded to the Narcotrend Index.

Results: With the six-level Richmond Agitation-Sedation Scale, the prediction probability (P K) for the Narcotrend Index (0.81) was better than for all other electroencephalography parameters (P < 0.01) except for relative power in the β band (P K 0.75). Using the three-level sedation scale instead, P K values for the Narcotrend Index (0.88) and all electroencephalography parameters improved (P < 0.01), and the Narcotrend Index was now superior to all electroencephalography parameters. Narcotrend Index values were distributed among the various sedation levels with significant overlap.

Conclusion: When used for assessment of propofol sedation in postsurgical cardiac intensive care unit patients, the Narcotrend Index can distinguish between very light and deep sedation. With respect to differentiation between light and moderate or moderate and deep sedation, the Narcotrend Index was not reliable in this study.

*Sophia Children's Hospital, Erasmus University Medical Center Rotterdam, Department of Anesthesiology, Rotterdam, The Netherlands

University Hospital Regensburg, Department of Anaesthesia, Franz-JosefStrauss-Allee, Regensburg, Germany

University of Regensburg, Department of Neurology, UniversitätsstraΒe, Regensburg, Germany

Correspondence to: Frank Weber, Department of Anaesthesiology, Erasmus University Medical Center Rotterdam - Sophia Children's Hospital, P.O. Box 2060, 3000CB Rotterdam, The Netherlands. E-mail: f.weber@erasmusmc.nl; Tel: +31 463 1145; Fax: +31 463 6804

aFormerly: Department of Anaesthesia, University Hospital Regensburg, Franz-JosefStrauss-Allee 11, 93053 Regensburg, Germany.

Accepted for publication 19 June 2007

First published online 7 August 2007

© 2008 European Society of Anaesthesiology