Electroencephalogram Approximate Entropy Correctly Classifies the Occurrence of Burst Suppression Pattern as Increasing Anesthetic Drug Effect

2000 ◽  
Vol 93 (4) ◽  
pp. 981-985 ◽  
Author(s):  
Jörgen Bruhn ◽  
Heiko Röpcke ◽  
Benno Rehberg ◽  
Thomas Bouillon ◽  
Andreas Hoeft
Keyword(s):  
Suppression Ratio ◽  
Drug Effect ◽  
Pearson Correlation ◽  
Approximate Entropy ◽  
Burst Suppression ◽  
Major Surgery ◽  
Median Frequency ◽  
Anesthetic Drug ◽  
Spectral Edge Frequency ◽  
Spectral Edge

Background Approximate entropy, a measure of signal complexity and regularity, quantifies electroencephalogram changes during anesthesia. With increasing doses of anesthetics, burst-suppression patterns occur. Because of the high-frequency bursts, spectrally based parameters such as median electroencephalogram frequency and spectral edge frequency 95 do not decrease, incorrectly suggesting lightening of anesthesia. The authors investigated whether the approximate entropy algorithm correctly classifies the occurrence of burst suppression as deepening of anesthesia. Methods Eleven female patients scheduled for elective major surgery were studied. After propofol induction, anesthesia was maintained with isoflurane only. Before surgery, the end-tidal isoflurane concentration was varied between 0.6 and 1.3 minimum alveolar concentration. The raw electroencephalogram was continuously recorded and sampled at 128 Hz. Approximate entropy, electroencephalogram median frequency, spectral edge frequency 95, burst-suppression ratio, and burst-compensated spectral edge frequency 95 were calculated offline from 8-s epochs. The relation between burst-suppression ratio and approximate entropy, electroencephalogram median frequency, spectral edge frequency 95, and burst-compensated spectral edge frequency 95 was analyzed using Pearson correlation coefficient. Results Higher isoflurane concentrations were associated with higher burst-suppression ratios. Electroencephalogram median frequency (r = 0.34) and spectral edge frequency 95 (r = 0.29) increased, approximate entropy (r = -0.94) and burst-compensated spectral edge frequency 95 (r = -0.88) decreased with increasing burst-suppression ratio. Conclusion Electroencephalogram approximate entropy, but not electroencephalogram median frequency or spectral edge frequency 95 without burst compensation, correctly classifies the occurrence of burst-suppression pattern as increasing anesthetic drug effect.

Approximate Entropy as an Electroencephalographic Measure of Anesthetic Drug Effect during Desflurane Anesthesia

2000 ◽  
Vol 92 (3) ◽  
pp. 715-726 ◽  
Author(s):  
Jörgen Bruhn ◽  
Heiko Röpcke ◽  
Andreas Hoeft
Keyword(s):  
Bispectral Index ◽  
Drug Effect ◽  
Statistical Parameter ◽  
Approximate Entropy ◽  
Pharmacodynamic Modeling ◽  
Median Frequency ◽  
Anesthetic Drug ◽  
Spectral Edge Frequency ◽  
Spectral Edge ◽  
Prediction Probability

Background The authors hypothesized that the electroencephalogram (EEG) during higher anesthetic concentrations would show more "order" and less "randomness" than at lower anesthetic concentrations. "Approximate entropy" is a new statistical parameter derived from the Kolmogorov-Sinai entropy formula which quantifies the amount of regularity in data. The approximate entropy quantifies the predictability of subsequent amplitude values of the EEG based on the knowledge of the previous amplitude values. The authors investigated the dose-response relation of the EEG approximate entropy during desflurane anesthesia in comparison with spectral edge frequency 95, median frequency, and bispectral index. Methods Twelve female patients were studied during gynecologic laparotomies. Between opening and closure of the peritoneum, end-tidal desflurane concentrations were varied between 0.5 and 1.6 minimum alveolar concentration (MAC). The EEG approximate entropy, median EEG frequency, spectral edge frequency 95, and bispectral index were determined and the performance of each to predict the desflurane effect compartment concentration, obtained by simultaneous pharmacokinetic-pharmacodynamic modeling, was compared. Results Electroencephalogram approximate entropy decreased continuously over the observed concentration range of desflurane. The performance of the approximate entropy (prediction probability PK = 0.86 +/- 0.06) as an indicator for desflurane concentrations is similar to spectral edge frequency 95 (PK = 0.86 +/- 0.06) and bispectral index (PK = 0.82 +/- 0.06) and is statistically significantly better than median frequency (PK = 0.78 +/- 0.06). Conclusions The amount of regularity in the EEG increases with increasing desflurane concentrations. The approximate entropy could be a useful EEG measure of anesthetic drug effect.

scholarly journals Concentration–Effect Relations, Prediction Probabilities (Pk), and Signal-to-noise Ratios of Different Electroencephalographic Parameters during Administration of Desflurane, Isoflurane, and Sevoflurane in Rats

2008 ◽  
Vol 108 (2) ◽  
pp. 276-285 ◽  
Author(s):  
Harald Ihmsen ◽  
Michael Schywalsky ◽  
Regina Plettke ◽  
Michael Priller ◽  
Florian Walz ◽  
...  
Keyword(s):  
Approximate Entropy ◽  
Burst Suppression ◽  
Concentration Effect ◽  
Median Frequency ◽  
Sprague Dawley ◽  
Signal To Noise ◽  
Spectral Edge Frequency ◽  
Spectral Edge ◽  
Anesthetic Effect ◽  
Prediction Probability

Background The authors investigated the suitability of different electroencephalographic parameters to quantify the anesthetic effect of desflurane, isoflurane, and sevoflurane in rats. Methods Ten male Sprague-Dawley rats were anesthetized in a randomized crossover design with maximum values of 11% desflurane, 2.1% isoflurane, and 3.5% sevoflurane. The electroencephalogram was recorded with implanted electrodes and a wireless telemetry system. Concentration-effect relations and signal-to-noise ratios were determined for the approximate entropy and for the median frequency and the spectral edge frequency, which were modified to account for spikes and burst suppression. The prediction probability Pk with respect to the response to a painful stimulus was determined. Results All drugs produced deep anesthesia with burst suppression and no response at the highest concentrations. The occurrence of spikes and burst suppression made a modification of median frequency and spectral edge frequency necessary to obtain Pk values greater than 0.5 and monotonic sigmoid concentration-effect relations. The Pk values were between 0.89 and 0.98, with significantly higher values for modified median frequency and spectral edge frequency during desflurane and sevoflurane. The signal-to-noise ratios were between 3.0 and 6.4 dB, with significantly better values for modified spectral edge frequency and approximate entropy during sevoflurane. Conclusions If modified for spikes and burst suppression, median frequency and spectral edge frequency as well as the unmodified approximate entropy were able to assess the anesthetic effect of desflurane, isoflurane, and sevoflurane in rats. For sevoflurane, the modified spectral edge frequency was best with regard to signal-to-noise ratio and prediction probability.

Spectral Entropy as an Electroencephalographic Measure of Anesthetic Drug Effect

2004 ◽  
Vol 101 (1) ◽  
pp. 34-42 ◽  
Author(s):  
Ann L.G. Vanluchene ◽  
Hugo Vereecke ◽  
Olivier Thas ◽  
Eric P. Mortier ◽  
Steven L. Shafer ◽  
...  
Keyword(s):  
Drug Effect ◽  
Rank Correlation ◽  
Burst Suppression ◽  
Spectral Entropy ◽  
Anesthetic Drug ◽  
Mixed Effect ◽  
Nonlinear Mixed Effect ◽  
Prediction Probability ◽  
Nonlinear Mixed Effect Modeling ◽  
Mixed Effect Modeling

Background The authors compared the behavior of two calculations of electroencephalographic spectral entropy, state entropy (SE) and response entropy (RE), with the A-Line ARX Index (AAI) and the Bispectral Index (BIS) and as measures of anesthetic drug effect. They compared the measures for baseline variability, burst suppression, and prediction probability. They also developed pharmacodynamic models relating SE, RE, AAI, and BIS to the calculated propofol effect-site concentration (Ceprop). Methods With institutional review board approval, the authors studied 10 patients. All patients received 50 mg/min propofol until either burst suppression greater than 80% or mean arterial pressure less than 50 mmHg was observed. SE, RE, AAI, and BIS were continuously recorded. Ceprop was calculated from the propofol infusion profile. Baseline variability, prediction of burst suppression, prediction probability, and Spearman rank correlation were calculated for SE, RE, AAI, and BIS. The relations between Ceprop and the electroencephalographic measures of drug effect were estimated using nonlinear mixed effect modeling. Results Baseline variability was lowest when using SE and RE. Burst suppression was most accurately detected by spectral entropy. Prediction probability and individualized Spearman rank correlation were highest for BIS and lowest for SE. Nonlinear mixed effect modeling generated reasonable models relating all four measures to Ceprop. Conclusions Compared with BIS and AAI, both SE and RE seem to be useful electroencephalographic measures of anesthetic drug effect, with low baseline variability and accurate burst suppression prediction. The ability of the measures to predict Ceprop was best for BIS.

Bispectral index, spectral edge frequency 95%, and median frequency recorded for various concentrations of isoflurane and sevoflurane in pigs

2003 ◽  
Vol 64 (7) ◽  
pp. 866-873 ◽  
Author(s):  
Maria F. Martin-Cancho ◽  
Juan R. Lima ◽  
Laura Luis ◽  
Veronica Crisostomo ◽  
Luis J. Ezquerra ◽  
...  
Keyword(s):  
Bispectral Index ◽  
Median Frequency ◽  
Spectral Edge Frequency ◽  
Spectral Edge

scholarly journals Comparison of Anesthetic Depth Indexes Based on Thalamocortical Local Field Potentials in Rats

2010 ◽  
Vol 112 (2) ◽  
pp. 355-363 ◽  
Author(s):  
Aura Silva ◽  
Hélder Cardoso-Cruz ◽  
Francisco Silva ◽  
Vasco Galhardo ◽  
Luís Antunes
Keyword(s):  
Local Field ◽  
Local Field Potentials ◽  
Burst Suppression ◽  
Permutation Entropy ◽  
Field Potentials ◽  
Anesthetic Depth ◽  
Spectral Edge Frequency ◽  
Spectral Edge ◽  
End Tidal ◽  
High Coherence

Background Local field potentials may allow a more precise analysis of the brain electrical activity than the electroencephalogram. In this study, local field potentials were recorded in the thalamocortical axis of rats to (i) compare the performance of several indexes of anesthetic depth and (ii) investigate the existence of thalamocortical correlated or disrupted activity during isoflurane steady-state anesthesia. Methods Five rats chronically implanted with microelectrodes were used to record local field potentials in the primary somatosensory cortex and ventroposterolateral thalamic nuclei at six 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; and after recovery. The approximate entropy, the index of consciousness, the spectral edge frequency, and the permutation entropy were estimated using epochs of 8 s. A correction factor for burst suppression was applied to the spectral edge frequency and to the permutation entropy. The correlation between the derived indexes and the end-tidal isoflurane was calculated and compared for the two studied brain regions indexes. Coherence analysis was also performed. Results The burst suppression-corrected permutation entropy showed the highest correlation with the end-tidal isoflurane concentration, and a high coherence was obtained between the two studied areas. Conclusions The permutation entropy corrected with the classic burst suppression ratio is a promising alternative to other indexes of anesthetic depth. Furthermore, high coherence level of activity exists between the somatosensory cortical and thalamic regions, even at deep isoflurane stages.

Electroencephalographic Approximate Entropy Changes in Healthy Volunteers during Remifentanil Infusion

2006 ◽  
Vol 104 (5) ◽  
pp. 921-932 ◽  
Author(s):  
Gyu-Jeong Noh ◽  
Kye-Min Kim ◽  
Yong-Bo Jeong ◽  
Seong-Wook Jeong ◽  
Hee-Suk Yoon ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Signal To Noise Ratio ◽  
Approximate Entropy ◽  
Signal To Noise ◽  
Spectral Edge Frequency ◽  
Spectral Edge ◽  
Median Baseline ◽  
Coefficients Of Variation ◽  
Prediction Probability ◽  
Noise Ratio

Background The aim of this study was to investigate the independent effect of remifentanil on the approximate entropy (ApEn) in frontoparietal montages. The authors investigated which montages were relevant to assess the remifentanil effect on the electroencephalogram. Spectral edge frequency and the canonical univariate parameter were used as comparators. Methods Twenty-eight healthy volunteers were enrolled. With recording of the electroencephalogram at the F3, F4, Cz, P3, and P4 montages, remifentanil was infused at the rate of 1-8 mug . kg . min for 15-20 min. The relation between remifentanil concentration and the electroencephalographic parameters were tested by Spearman correlation. Signal-to-noise ratio, artifact robustness, coefficient of variation of the median baseline and maximal electroencephalographic effects, and ratio of average maximal electroencephalographic effect to interindividual baseline variability were measured. The performance of ApEn as an index of remifentanil effect site concentrations was tested by prediction probability. Results Approximate entropy showed significant correlation (R = -0.6465, P < 0.0001) with remifentanil concentration. It provided comparable signal-to-noise ratio, artifact robustness, and ratio of average maximal electroencephalographic effect to interindividual baseline variability to 95% spectral edge frequency. The coefficients of variation of the median baseline and maximal electroencephalo graphic effects were smallest in ApEn. Parietal montages showed higher ratios of average maximal electroencephalographic effect to interindividual baseline variability for all electroencephalographic parameters and lower coefficients of variation of the baseline values for ApEn and 95% spectral edge frequency than frontal montages. The prediction probability of ApEn was 0.7730. Conclusions Approximate entropy derived from a parietal montage is appropriate for the assessment of the remifentanil effect on the electroencephalogram.

scholarly journals Median Frequency Revisited

2007 ◽  
Vol 107 (3) ◽  
pp. 397-405 ◽  
Author(s):  
Denis Jordan ◽  
Gudrun Stockmanns ◽  
Eberhard F. Kochs ◽  
Gerhard Schneider
Keyword(s):  
Spectral Parameter ◽  
Bispectral Index ◽  
Median Frequency ◽  
Spectral Parameters ◽  
Data Set ◽  
Spectral Edge Frequency ◽  
Spectral Edge ◽  
Prediction Probability ◽  
Hypnotic Agent ◽  
The Fourier Transform

Background In the past, several electroencephalographic parameters have been presented and discussed with regard to their reliability in discerning consciousness from unconsciousness. Some of them, such as the median frequency and spectral edge frequency, are based on classic spectral analysis, and it has been demonstrated that they are of limited capacity in differing consciousness and unconsciousness. Methods A generalized approach based on the Fourier transform is presented to improve the performance of electroencephalographic parameters with respect to the separation of consciousness from unconsciousness. Electroencephalographic data from two similar clinical studies (for parameter development and evaluation) in adult patients undergoing general anesthesia with sevoflurane or propofol are used. The study period was from induction of anesthesia until patients followed command after surgery and includes a reduction of the hypnotic agent after tracheal intubation until patients followed command. Prediction probability was calculated to assess the ability of the parameters to separate consciousness from unconsciousness. Results On the basis of the training set of 40 patients, a new spectral parameter called weighted spectral median frequency was designed, achieving a prediction probability of 0.82 on the basis of the "classic" electroencephalographic frequency range up to 30 Hz. Next, in the evaluation data set, the prediction probability was 0.79, which is higher than the prediction probability of median frequency (0.58) or spectral edge frequency (0.59) and the Bispectral Index (0.68) as calculated from the same data set. Conclusions A more general approach of the design of spectral parameters leads to a new electroencephalographic spectral parameter that separates consciousness from unconsciousness significantly better than the Bispectral Index.

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