| Reference code: | PT/FB/BL-2008-126.18 |
| Location: | Arquivo PCA - Pastas 16 a 17/2008
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Title:
| Application of Tsallis entropy to quantify burst suppression during isoflurane anesthesia in rats
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| Publication year: | 2010
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URL:
| http://www.asaabstracts.com/strands/asaabstracts/abstract.htm;jsessionid=36DCF5C43778F1EBDF689BD05364757B?year=2010&index=5&absnum=1433
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| Abstract/Results: | ABSTRACT:
Introduction: Burst suppression (BS) activity of the electroencephalogram (EEG) reflects deep anesthesia and has been used to help intra operative anesthetic depth monitoring. It appears as a transitional pattern between isoelectricity and high-frequency EEG and its quantification is normally based in the percentage of isoelectricity in EEG epochs¹. Tsallis entropy (TE) has been recently applied to quantify the presence of BS in the EEG of rats after cardiac arrest², but there is no data on this analysis during anesthesia. The use of a non-linear analysis based method (TE) could be a more practical alternative to the traditional BS ratio, as the first one does not need the set of an amplitude limit to consider the signal as isoelectric that may vary with amplitude and recording conditions. In the present study, the potential to use TE to quantify BS was accessed using a high resolution signal called local field potentials recorded in rats under isoflurane anesthesia. Methods: Five rats chronically implanted with microelectrodes were used to record local field potentials in the primary somatosensory at 6 periods: before induction of anesthesia; in the last 5 min of randomized 20 min steady state end-tidal 0.8%, 1.1%, 1.4% and 1.7% isoflurane concentrations (etISO) and after recovery. A 50 Hz notch filter was applied to the signal before analysis. Four epochs of 12 seconds (3000 data points per epoch) were selected from the last 5 min of each concentration step and analyzed: the classic burst suppression ratio (BSR)[start_en]00B9; and Tzallis entropy² were calculated. The Spearman Rank correlation coefficient was calculated between etISO and the BSR and between etISO and TE for each rat (24 pairs of data each rat). A paired sample t-test was used to compare the absolute values of the correlation coefficients of the BSR and the TE (n=5). Results: Figure 1 shows the absolute values for the correlation coefficients between etISO and BSR and between etISO and TE for the five rats.[figure1]The TE varied between 0,429 and 0.499 and decreased with increasing anesthetic dosages, resulting in negative correlation coefficients. The BSR had significant positive correlation coefficients, except in one animal in which the correlation coefficient was bellow 0.5. There were no significant differences between the correlation coefficients of the two indexes with etISO. However, TE had a higher mean of the correlation coefficients. Conclusions: Although the BSR is a very simple and fast method to quantify BS in the EEG, the use of a non-linear analysis method such as TE eliminates the need to perform visual inspection of the signal in order to pre-set the amplitude limit of isoelectricity. These results point out the potential of TE to be applied in practice. However, further investigation is required with extracranial signals.
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| Accessibility: | Document does not exist in file
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Language:
| eng
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Author:
| Silva, A.
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Secondary author(s):
| Cardoso-Cruz, H., Galhardo, V., Antunes, L.
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Document type:
| Online abstract
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Number of reproductions:
| 1
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Reference:
| Silva, A., Cardoso-Cruz, H., Galhardo, V., & Antunes, L. (2010, October). Application of Tsallis entropy to quantify burst suppression during isoflurane anesthesia in rats. Poster presented at the 2010 Annual Meeting of the American Society of Anesthesiology, San Diego, USA.
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| Indexed document: | No
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| Keywords: | Burst suppression / Tsallis entropy / Anesthetic depth / Rat
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