The Narcotrend Index: Classification Algorithm, Correlation with Propofol Effect-Site Concentrations, and Comparison with Spectral Parameters / Der Narcotrend-Index: Klassifikationsalgorithmus, Korrelation mit Propofol-Effekt-Site-Konzentrationen und Vergleich mit Spektralparametern

Abstract A reliable assessment of the depth of hypnosis during sedation and general anaesthesia using the EEG is a subject of current interest. The Narcotrend Index implemented in the latest version 4.0 of the EEG monitor Narcotrend® provides an automatic classification of the EEG on a scale ranging from 100 (awake) to 0 (very deep hypnosis, EEG suppression). The classification algorithms implemented in the EEG monitor Narcotrend are described. In a study the correlation of the propofol effect-site concentration with the Narcotrend Index and with the traditional spectral parameters total power, relative power in the standard frequency bands δ, θ, α, and β, median frequency, 95 % spectral edge frequency, burst-compensated spectral edge frequency, and spectral entropy was investigated. The Narcotrend Index had the highest average correlation with the propofol effect-site concentration and the smallest variability of the individual correlation values. Moreover, the Narcotrend Index was the only parameter which showed a monophasic trend over the whole investigated time period. The Narcotrend monitor can make a significant contribution to the improvement of the quality of anaesthesia by adjusting the dosage of hypnotics to individual patient needs. Die zuverlässige Bewertung der Schlaftiefe während Sedierung und Narkose ist ein Thema von aktuellem Interesse. Der Narcotrend-Index, der in der neusten Version 4.0 des EEG-Monitors Narcotrend® implementiert ist, liefert eine automatische Klassifikation des EEG auf einer Skala von 100 (wach) bis 0 (tiefste Narkose). Die Klassifikationsalgorithmen des Narcotrend-EEG-Monitors werden beschrieben. In einer Studie wurde die Korrelation der Propofol-Effekt-Site-Konzentration mit dem Narcotrend-Index sowie mit den klassischen Spektralparametern Gesamtleistung, relative Leistung in den Standard-Frequenzbändern δ, θ, α und β, Median-Frequenz, 95 % spektrale Eckfrequenz, burst-korrigierte spektrale Eckfrequenz und spektrale Entropie untersucht. Der Narcotrend-Index zeigte die höchste mittlere Korrelation mit der Propofol-Effekt-Site-Konzentration und die geringste Streuung der individuellen Korrelationen. Zudem war der Narcotrend-Index der einzige Parameter, der einen monophasischen Trend über den gesamten untersuchten Zeitverlauf aufwies. Der Narcotrend kann einen wertvollen Beitrag zur Verbesserung der Narkosequalität durch eine individuell auf den einzelnen Patienten abgestimmte Hypnotika-Dosierung leisten.

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