Browsing by Author "FERREIRA, D.A."
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- Clinical variables related to propofol effect‐site concentrations at recovery of consciousness after neurosurgical proceduresPublication . NUNES, C.S.; FERREIRA, D.A.; ANTUNES, L.; AMORIM, P.J Neurosurg Anesthesiol. 2005 Apr;17(2):110-4. Clinical variables related to propofol effect-site concentrations at recovery of consciousness after neurosurgical procedures. Nunes CS, Ferreira DA, Antunes L, Amorim P. CECAV, Universidade de Trás-os-Montes de Alto Douro, Vila-Real, Portugal. ccnunes@fc.up.pt Abstract Target controlled infusion (TCI) systems and computer data acquisition software are increasingly used in anesthesia. It was hypothesized that the use of such systems might allow retrieval of information useful to anticipate the effect-site concentrations of propofol at which patients would recover from anesthesia. The goal of the study was to identify variables related to propofol effect-site concentrations at recovery of consciousness (ROC). Sixteen patients with a Glasgow of 15, ASA 1 or 2, subjected to neurosurgical procedures, received TIVA with TCI propofol and remifentanil. Data were collected every 5 seconds from Datex AS3 and Aspect A200XP (BIS). Effect-site TCI was used for propofol (initial effect target 5.0 microg/ml) and for remifentanil (initial plasma target 2.5 ng/ml). All clinical events were noted. Variables possibly related to propofol effect-site concentration at ROC were selected. Data are expressed as mean +/- SD. Effect-site propofol concentration at ROC was 1.3 +/- 0.5 microg/ml. A positive correlation was found between propofol effect-site concentration at ROC and: age (49.3 +/- 17 years) (P = 0.003); mean remifentanil dose during surgery (0.11 +/- 0.05 microg/kg/min) (P = 0.003); mean propofol dose during surgery (0.12 +/- 0.03 mg/kg/min) (P = 0.046); and remifentanil effect-site concentration at ROC (2.85 +/- 2.06 ng/ml) (P = 0.002). Propofol effect-site concentrations were not correlated with: weight, height, LBM, duration of anesthesia, minimum BIS at induction (30.4 +/- 6.8), time till minimum BIS (4.7 +/- 2.2 min), mean and median BIS during surgery (38.2 +/- 4.5 and 37.8 +/- 5.3). BIS-related variables were not useful as ROC predictors. Only drug variables and age correlated with propofol effect-site concentrations at ROC. PMID: 15840999 [PubMed - indexed for MEDLINE]
- Modeling Anesthetic Drugs' Pharmacodynamic Interaction on the Bispectral Index of the EEG: the Influence of Heart Rate.Publication . NUNES, C.S.; MENDONCA, T.; BRAS, S.; FERREIRA, D.A.; AMORIM, P.Conf Proc IEEE Eng Med Biol Soc. 2007;2007:6480-3. Modeling anesthetic drugs' pharmacodynamic interaction on the bispectral index of the EEG: the influence of heart rate. Nunes CS, Mendonca T, Bras S, Ferreira DA, Amorim P. Faculdade de Ciências da Universidade do Porto, Departamento de Matemática Aplicada, Rua do Campo Alegre 687, 4169-007 Porto, Portugal. ccnunes@fc.up.pt Abstract The effect of drugs' interaction on the brain signal Bispectral Index (BIS) is of great importance for an anesthesia control drug infusion system. In this study, the objective was to inspect the influence of patient's heart rate on the effect of the drugs on BIS. With this goal, the patient's heart rate was incorporated in an drug interaction model. The model was fitted per patient during anesthesia induction, and tested for prediction under surgery. The results showed that the model with time changing parameters incorporating patient's heart rate has a better performance than a non adjusted model. Three clusters of models were also identified using the fuzzy c-means algorithm. These clusters will help to distinguish between different patients' dynamics. PMID: 18003509 [PubMed - indexed for MEDLINE]
- Radial basis function neural networks versus fuzzy models to predict return of consciousness after general anesthesiaPublication . NUNES, C.S.; MENDONCA, T.F.; AMORIM, P.; FERREIRA, D.A.; ANTUNES, L.M.Conf Proc IEEE Eng Med Biol Soc. 2004;2:865-8. Radial basis function neural networks versus fuzzy models to predict return of consciousness after general anesthesia. Nunes CS, Mendonca TF, Amorim P, Ferreira DA, Antunes LM. Dept. of Appl. Math., Porto Univ., Portugal. Abstract This work presents two modelling techniques to predict return of consciousness (ROC) after general anaesthesia, considering the effect concentration of the anaesthetic drug at awakening. First, several clinical variables were statistically analysed to determine their correlation with the awakening concentration. The anaesthetic and the analgesic mean dose during surgery, and the age of the patient, proved to have significantly high correlation coefficients. Variables like the mean bispectral index value during surgery, duration of surgery did not present a statistical relation with ROC. Radial basis function (RBF) neural networks were trained relating different sets of clinical values with the anaesthetic drug effect concentration at awakening. Secondly, fuzzy models were built using an adaptive network-based fuzzy inference system (ANFIS) also relating different sets of variables. Clinical data was used to train and test the models. The fuzzy models and RBF neural networks proved to have good prediction properties and balanced results. PMID: 17271814 [PubMed]
- Regular clinical use bispectral índex monitoring may result in lighter depth of anesthesia as reflected in average higher bispectral index valuesPublication . NUNES, C.S.; FERREIRA, D.A.; ANTUNES, L.M.; AMORIM, P.Anesthesiology. 2005 Dec;103(6):1320-1. Regular clinical use bispectral index monitoring may result in lighter depth of anesthesia as reflected in average higher bispectral index values. Nunes CS, Ferreira DA, Antunes LM, Amorim P. PMID: 16306760 [PubMed - indexed for MEDLINE]