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EEG entropy monitoring of depth of anaesthesia: pharmacokinetic and dynamic modelling
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Abstract(s)
Because of the difficulty in analyzing raw electroencephalographic signal, several electroencephalographic
monitors have been developed to aid anaesthetists on their
task to maintain adequate anaesthesia. Spectral Entropy is
used as a measure of electroencefalographic effects of drugs
in human patients, and is a valuable tool to predict depth of
anaesthesia. Monitors with implemented entropy algorithms,
process the electroencephalogram (EEG) and are in current
use at the operating room. In this study we used the EEG
collected in rats and applied the Shannon entropy over the
signal. The information obtained was used as an indicator of
depth of anaesthesia. The main objective was to model the
relation between the depth of anaesthesia in rats (entropy)
and the propofol infusion rates, with the purpose of obtaining
a closed-loop control for propofol infusions. Five adult rats
were sedated with isoflurane, cannulated and equipped for
the EEG collection. After the preparation, anaesthesia was
induced with propofol infusions, using different infusion rates
on each rat. The collected EEG (125Hz) was processed using an
entropy algorithm developed in MATLAB
R 7 that determined
the entropy value at each second using the preceding 15s
of signal. Pharmacokinetic models were fitted for each rat
using bi and tri-compartmental models; the pharmacodynamic
phase was also modelled for each rat. The relation between
obtained propofol effect-site concentrations and the entropy
values was modelled by a Hill Equation. The model obtained
for the relation between infusion rates and entropy values was
evaluated using the mean absolute deviation (MAD) and the
relative mean square error (RMSE) for models comparative
analysis.
Description
Keywords
Citation
A. Castro, N. Bressan, L. Antunes and C. S. Nunes, "EEG entropy monitoring of depth of anaesthesia: Pharmacokinetic and dynamic modelling," 2007 European Control Conference (ECC), Kos, Greece, 2007, pp. 2535-2540
Publisher
IEEE