Time-frequency balanced spectral entropy as a measure of anesthetic drug effect in central nervous system during sevoflurane, propofol, and thiopental anesthesia

• Published in: Acta anaesthesiologica Scandinavica 2004-02, Vol.48 (2), p.145-153
• Main Authors: Vakkuri, A., Yli-Hankala, A., Talja, P., Mustola, S., Tolvanen-Laakso, H., Sampson, T., Viertiö-Oja, H.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Anesthesia; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Anesthetics - pharmacology; Biological and medical sciences; desflurane; Electroencephalography - drug effects; Electromyography - drug effects; Entropy; general anesthesia; Humans; Medical sciences; Methyl Ethers - pharmacology; Middle Aged; propofol; Propofol - pharmacology; Sensitivity and Specificity; Sevoflurane; thiopental; Thiopental - pharmacology; Time Factors
• ISSN: 0001-5172; 1399-6576
• DOI: 10.1111/j.0001-5172.2004.00323.x

Background:  Time‐frequency balanced spectral entropy of electroencephalogram (EEG) and frontal electromyogram (FEMG) is a novel measure of hypnosis during anesthesia. Two Entropy parameters are described: Response entropy (RE) is calculated from EEG and FEMG; and State Entropy (SE) is calculated mainly from EEG. This study was performed to validate their performance during transition from consciousness to unconsciousness under different anesthetic agents. Methods:  Response entropy, SE [S/5™ Entropy Module, M‐ENTROPY (later in text: Entropy), Datex‐Ohmeda Division, Instrumentarium Corp., Helsinki, Finland] and BIS (BIS XP, A‐2000, Aspect Medical Systems, Newton, MA) data were collected from 70 patients; 30 anesthetized with propofol 2 mg kg−1, 20 with sevoflurane inhalation, and 20 with thiopental 5 mg kg−1. Loss and regaining of consciousness (LOC, ROC) was tested every 10 s, and sensitivity, specificity, and prediction probability (Pk) were calculated. Behavior of the indices was studied. Results:  Sensitivity, specificity, and Pk values for consciousness were high and similar for all indices. During regaining of consciousness after propofol bolus, RE, SE, and BIS values recovered by 81 ± 22%, 75 ± 26%, and 59 ± 18% (mean ± SD), respectively, from the minimum relative to their baseline. After thiopental bolus, RE, SE, and BIS values recovered by 86±21%, 88 ± 13%, and 63 ± 14%, respectively. The relative rise was higher in RE and SE compared with BIS (P