Abstract
Highlights: ► Twelve entropy indices were systematically compared in monitoring depth of anesthesia and detecting burst suppression.► Renyi permutation entropy performed best in tracking EEG changes associated with different anesthesia states.► Approximate Entropy and Sample Entropy performed best in detecting burst suppression.Objective: Entropy algorithms have been widely used in analyzing EEG signals during anesthesia. However, a systematic comparison of these entropy algorithms in assessing anesthesia drugs' effect is lacking. In this study, we compare the capability of 12 entropy indices for monitoring depth of anesthesia (DoA) and detecting the burst suppression pattern (BSP), in anesthesia induced by GABAergic agents.Methods: Twelve indices were investigated, namely Response Entropy (RE) and State entropy (SE), three wavelet entropy (WE) measures [Shannon WE (SWE), Tsallis WE (TWE), and Renyi WE (RWE)], Hilbert-Huang spectral entropy (HHSE), approximate entropy (ApEn), sample entropy (SampEn), Fuzzy entropy, and three permutation entropy (PE) measures [Shannon PE (SPE), Tsallis PE (TPE) and Renyi PE (RPE)]. Two EEG data sets from sevoflurane-induced and isoflurane-induced anesthesia respectively were selected to assess the capability of each entropy index in DoA monitoring and BSP detection. To validate the effectiveness of these entropy algorithms, pharmacokinetic/pharmacodynamic (PK/PD) modeling and prediction probability (Pk) analysis were applied. The multifractal detrended fluctuation analysis (MDFA) as a non-entropy measure was compared.Results: All the entropy and MDFA indices could track the changes in EEG pattern during different anesthesia states. Three PE measures outperformed the other entropy indices, with less baseline variability, higher coefficient of determination (R2) and prediction probability, and RPE performed best; ApEn and SampEn discriminated BSP best. Additionally, these entropy measures showed an advantage in computation efficiency compared with MDFA.Conclusion: Each entropy index has its advantages and disadvantages in estimating DoA. Overall, it is suggested that the RPE index was a superior measure. Investigating the advantages and disadvantages of these entropy indices could help improve current clinical indices for monitoring DoA.
Highlights
In the operating room, general anesthesia is important to guarantee successful surgery and ensure patients’ safety and comfort
All the entropy and multifractal detrended fluctuation analysis (MDFA) indices could track the changes in EEG pattern during different anesthesia states
Three permutation entropy (PE) measures outperformed the other entropy indices, with less baseline variability, higher coefficient of determination (R2) and prediction probability, and Renyi PE (RPE) performed best; approximate entropy (ApEn) and sample entropy (SampEn) discriminated burst suppression pattern (BSP) best. These entropy measures showed an advantage in computation efficiency compared with MDFA
Summary
General anesthesia is important to guarantee successful surgery and ensure patients’ safety and comfort. The reliable monitoring of anesthetic drug effects on the brain is a clinical concern for anesthesiologists (Monk et al, 2005). The central nervous system (CNS) is the main target of anesthetic drugs. Originated in CNS, the electroencephalogram (EEG) reflects the neural activities of brain, and has been widely used as a surrogate parameter to quantify the anesthetic drug effect Only limited information can be obtained from the EEG signals purely by waveform observation. With the development of signal processing, various methods have been applied to analyze, identify or detect mental disorders and consciousness mechanisms from EEG signals (Okogbaa et al, 1994; Natarajan et al, 2004; Abásolo et al, 2006), as well as evaluating the effects of anesthesia
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