Auditory Event-Related Potentials, Bispectral Index, and Entropy for the Discrimination of Different Levels of Sedation in Intensive Care Unit Patients

• DOI: 10.1213/ane.0b013e3181acc85d
• Publication Date: 2009-08-15T07:14:22Z
• Authors: Matthias Haenggi; Heidi Ypparila-Wo...; Sarah Buerki; Rebekka Schlauri; Ilkka Korhonen; Jukka Takala; Stephan M. Jakob
• Keywords: Bispectral index

BACKGROUND: Sedation protocols, including the use of sedation scales and regular stops, help to reduce length mechanical ventilation intensive care unit stay. Because clinical assessment depth is labor-intensive, performed only intermittently, interferes with sleep, processed electrophysiological signals from brain have gained interest as surrogates. We hypothesized that auditory event-related potentials (ERPs), Bispectral Index® (BIS), Entropy® can discriminate among clinically relevant levels. METHODS: studied 10 patients after elective thoracic or abdominal surgery general anesthesia. Electroencephalogram, BIS, state entropy (SE), response (RE), ERPs were recorded immediately in at Richmond Agitation-Sedation Scale (RASS) scores −5 (very deep sedation), −4 (deep −3 −1 (moderate 0 (awake) during decreasing target-controlled propofol remifentanil. Reference measurements for baseline levels before several days operation. RESULTS: At baseline, RASS −5, −4, −1, 0, BIS was 94 [4] (median, IQR), 47 [15], 68 [9], 75 [10], 88 [6]; SE 87 [3], 46 60 [22], 74 [21], [5]; RE 97 [4], 48 71 [25], 81 [18], 96 respectively (all P < 0.05, Friedman Test). Both Entropy had high variabilities. When ERP N100 amplitudes considered alone, did not differ significantly Nevertheless, discriminant analysis two parameters principal component revealed a prediction probability PK value 0.89 differentiating sedation, moderate awake state. The corresponding RE, SE, 0.88, 0.89, 0.85, respectively. CONCLUSIONS: Neither nor replace standard scoring systems. Discrimination very deep, moderate, no anesthesia be provided by electroencephalograms, similar PKs. inter- intraindividual variability precludes defining target range values predict level critically ill using these parameters. unknown.