Quantitative EEG Correlations with Brain Glucose Metabolic Rate during Anesthesia in Volunteers 

1998 ◽  
Vol 89 (2) ◽  
pp. 323-333 ◽  
Author(s):  
Michael T. Alkire
Keyword(s):  
Bispectral Index ◽  
Cerebral Metabolism ◽  
Functional Brain Imaging ◽  
Total Power ◽  
Alpha Power ◽  
Median Frequency ◽  
Isoflurane Anesthesia ◽  
Spectral Edge ◽  
Beta Power ◽  
Metabolic Reduction

Background To help elucidate the relationship between anesthetic-induced changes in the electroencephalogram (EEG) and the concurrent cerebral metabolic changes caused by anesthesia, positron emission tomography data of cerebral metabolism obtained in volunteers during anesthesia were correlated retrospectively with various concurrently measured EEG descriptors. Methods Volunteers underwent functional brain imaging using the 18fluorodeoxyglucose technique; one scan always assessed awake-baseline cerebral metabolism (n = 7), and the other scans assessed metabolism during propofol sedation (n = 4), propofol anesthesia (n = 4), or isoflurane anesthesia (n = 5). The EEG was recorded continuously during metabolism assessment using a frontal-mastoid montage. Power spectrum variables, median frequency, 95% spectral edge, and bispectral index (BIS) values subsequently were correlated with the percentage of absolute cerebral metabolic reduction (PACMR) of glucose utilization caused by anesthesia. Results The percentage of absolute cerebral metabolic reduction, evident during anesthesia, trended median frequency (r = -0.46, P = 0.11), and the spectral edge (r = -0.52, P = 0.07), and correlated with anesthetic type (r = -0.70, P < 0.05), relative beta power (r = -0.60, P < 0.05), total power (r = 0.71,P < 0.01), and bispectral index (r = -0.81,P < 0.001). After controlling for anesthetic type, only bispectral index (r = 0.40, P = 0.08) and alpha power (r = 0.37, P = 0.10) approached significance for explaining residual percentage of absolute cerebral metabolic reduction prediction error. Conclusions Some EEG descriptors correlated linearly with the magnitude of the cerebral metabolic reduction caused by propofol and isoflurane anesthesia. These data suggest that a physiologic link exists between the EEG and cerebral metabolism during anesthesia that is mathematically quantifiable.

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

Shannon Entropy Applied to the Measurement of the Electroencephalographic Effects of Desflurane

2001 ◽  
Vol 95 (1) ◽  
pp. 30-35 ◽  
Author(s):  
Jörgen Bruhn ◽  
Lutz E. Lehmann ◽  
Heiko Röpcke ◽  
Thomas W. Bouillon ◽  
Andreas Hoeft
Keyword(s):  
Shannon Entropy ◽  
Bispectral Index ◽  
Approximate Entropy ◽  
Total Power ◽  
Pharmacodynamic Modeling ◽  
Effect Compartment ◽  
Median Frequency ◽  
Equal Distribution ◽  
Drug Concentrations ◽  
Skew Distribution

Background The Shannon entropy is a standard measure for the order state of sequences. It quantifies the degree of skew of the distribution of values. Increasing hypnotic drug concentrations increase electroencephalographic amplitude. The probability density function of the amplitude values broadens and flattens, thereby changing from a skew distribution towards equal distribution. We investigated the dose-response relation of the Shannon entropy of the electroencephalographic amplitude values during desflurane monoanesthesia in comparison with previously used electroencephalographic parameters. Methods Electroencephalographic records previously obtained in 12 female patients during gynecologic laparotomies were reanalyzed. Between opening and closure of the peritoneum, desflurane vapor settings were varied between 0.5 and 1.6 minimum alveolar concentration. Electroencephalographic Shannon entropy, approximate entropy, median electroencephalographic frequency, SEF 95, total power, log total power, and Bispectral Index were determined, and their correlations with the desflurane effect compartment concentration, obtained by simultaneous pharmacokinetic-pharmacodynamic modeling, were compared. Results The electroencephalographic Shannon entropy increased continuously over the observed concentration range of desflurane. The correlation of the Shannon entropy (R2 = 0.84+/-0.08, mean +/- SD) with the desflurane effect compartment concentrations is similar to approximate entropy (R2 = 0.85+/-0.12), SEF 95 (R2 = 0.85+/-0.10), and Bispectral Index (R2 = 0.82+/-0.13) and is more statistically significant than median frequency (R2 = 0.72+/-0.17), total power (R2 = 0.67+/-0.18), and log total power (R2 = 0.80+/-0.09). Conclusions The Shannon entropy seems to be a useful electroencephalographic measure of anesthetic drug effect.

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.

Bispectral index, spectral edge frequency 95% and median frequency recorded at varying desflurane concentrations in pigs

2006 ◽  
Vol 81 (3) ◽  
pp. 373-381 ◽  
Author(s):  
María F. Martín-Cancho ◽  
Juan R. Lima ◽  
L. Luis ◽  
Verónica Crisóstomo ◽  
María A. López ◽  
...  
Keyword(s):  
Bispectral Index ◽  
Median Frequency ◽  
Spectral Edge Frequency ◽  
Spectral Edge

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.

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