Browsing by Author "Mendonça, Teresa F."
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- Modelling drugs' pharmacodynamic interaction during general anaesthesia: the choice of pharmacokinetic modelPublication . Nunes, Catarina S.; Mendonça, Teresa F.; Antunes, Luís; Ferreira, David A.; Lobo, Francisco; Amorim, PedroThe effect of drugs’ interaction on the brain signal Bispectral Index (BIS) is of great importance for an anaesthesia control drug infusion system. In this study, two renowned pharmacokinetic (PK) models for propofol are compared, in order to evaluate its influence on the performance/predictably of a drug interaction model for BIS, considering data of 45 patients. The model was fitted per patient during anaesthesia induction, and tested for prediction under surgery. The results showed that the choice of PK model had influence on the overall performance. In the prediction phase, only one PK model presented good results with small errors.
- Neuro-fuzzy techniques to model pharmacodynamic interactions between anesthetic drugs on the bispectral index: a preliminary studyPublication . Nunes, Catarina S.; Ferreira, David A.; Mendonça, Teresa F.; Amorim, Pedro; Antunes, Luís M.The aim of this preliminary study was to try to identify the effect of propofol and remifentanil on bispectral index of the electroencephalogram (BIS), and to determine if a model can be generalized between different patients. We used the data from three patients under stable propofol and remifentanil anesthesia for neurosurgical procedures. A Takagi-Sugeno-Kang (TSK) fuzzy model was used to describe the effect of interaction of propofol and remifentanil on BIS. An Adaptive Network-Fuzzy Inference System (ANFIS) was used to obtain the parameters of the TSK model. The ANFIS was able to optimize the parameters of the fuzzy TSK model. The obtained TSK model reflected the data trend and was able to capture the synergistic interaction between propofol and remifentanil during the maintenance phase of anesthesia. The model was trained with the data of two patients and tested with the data of a third patient. Different patients have different physiological responses and this preliminary study results suggested that the BIS values were independent of patients’ variability. This result should be improved using a larger set of data with more patients.
- Predictive adaptive control of the bispectral Index of the EEG (BIS): using the intravenous anaesthetic drug propofolPublication . Nunes, Catarina S.; Mendonça, Teresa F.; Magalhães, Hugo; Lemos, João M.; Amorim, PedroThe problem of controlling the level of unconsciousness measured by the Bispectral Index of the EEG (BIS) of patients under anaesthesia, is considered. It is assumed that the manipulated variable is the infusion rate of the hypnotic drug propofol, while the drug remifentanil is also administered for analgesia. Since these two drugs interact, the administration rate of remifentanil is considered as an accessible disturbance. In order to tackle the high uncertain present on the system, the predictive adaptive controller MUSMAR is used. The performance of the controller is illustrated by means of simulation with 45 patient individual adjusted models, which incorporate the effect of the drugs interaction on BIS. This controller structure proved to be robust to the remifentanil disturbance, different reference values and noise. A reduction of propofol consumption was also observed when comparing to the real clinical dose used for a similar BIS trend.