In this master's thesis, we focus on the development and evaluation of models for assessing and managing the depth of anesthesia using processed electroencephalographic (EEG) signals. The aim of the research is to improve the accuracy and efficiency of anesthesia management during surgical procedures, which is crucial for patient safety and comfort.
The thesis first presents pharmacokinetic and pharmacodynamic models for anesthesia, which describe the absorption, distribution, metabolism, and excretion of anesthetics, as well as their effects on the body. Special attention is given to the comparison of established models for propofol and remifentanil.
Next, various indices based on processed EEG signals for measuring the depth of anesthesia are discussed, particularly the BIS (Bispectral Index) and PSi (Patient State Index). Both methods are based on EEG signal analysis and allow for the assessment of the patient's state during anesthesia. A simulation model was developed as part of the research, enabling a comparison of both indices.
The thesis then introduces new population models based on measured data that better adjust the depth of anesthesia for the selected population. The use of machine learning methods, such as neural networks and decision trees, for predicting optimal model parameters for individual patients is also presented. The analysis is further extended to include the effect of the analgesic remifentanil on the depth of anesthesia, and a modified model that accounts for the combined effects of propofol and remifentanil is introduced. The simulation results show improvements in predicting the depth of anesthesia. A residual model is then developed, which adjusts predictions based on individual patient differences. This model allows for real-time adjustments during surgery, improving prediction accuracy and contributing to the safer use of anesthesia.
The research results indicate that the use of enhanced pharmacokinetic and pharmacodynamic models can significantly contribute to more accurate modeling of anesthesia depth. This leads to a reduction in the risk of complications during surgery and a faster recovery for patients after the procedure.
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