Proceedings of the 1998 IEEE International Conference on Control Applications (Cat. No.98CH36104), 1998
... Pedro Lagof, Teresa Mendonqaf*, Lio Gonplves-+ Departamento de Nlatem6tica Aplicada, Faculdad... more ... Pedro Lagof, Teresa Mendonqaf*, Lio Gonplves-+ Departamento de Nlatem6tica Aplicada, Faculdade de CiGncias da Universidade do Port0 ... Abstract A digital PID controller incorporating several modi-fications to accommodate the characteristics of neu-romuscular blockade ...
Revista portuguesa de cardiologia : orgão oficial da Sociedade Portuguesa de Cardiologia = Portuguese journal of cardiology : an official journal of the Portuguese Society of Cardiology, 1997
The aim of this study was to assess the influence of detraining and training on the autonomic con... more The aim of this study was to assess the influence of detraining and training on the autonomic control of heart rate (HR), using time and frequency (spectral analysis) domain components of heart rate variability. Sixteen professional football players (26.7 +/- 3.8 years; 74.9 +/- 4.1 kg; 177 +/- 6.3 cm) were analysed at the end of a 1 month holiday (detraining) and after a 6 week training period (training). HR was recorded over 15 minutes with Holter equipment. The athletes rested in a supine position, in a quiet place and all test were performed between 8 and 10 AM. The subjects were requested to refrain from meals or caffeine for 12 hours before testing. In spite of the high intensity of the training period, there was no significant change in results from detraining condition to training condition. These results can have two possible explanations: (i) the high level of cardiovascular capacity in the detraining trial originated by the recreative physical activity that the players un...
Revista portuguesa de cardiologia : orgão oficial da Sociedade Portuguesa de Cardiologia = Portuguese journal of cardiology : an official journal of the Portuguese Society of Cardiology, 1996
Arterial baroreceptors are sensitive to variation in both blood and pulse pressure. When there is... more Arterial baroreceptors are sensitive to variation in both blood and pulse pressure. When there is an increase in those pressures, the baroreceptors increase the rhythm in which electric impulses are discharged. The impulses are transmitted by the receptors to the nervous centres of the brainstem. Once processed, these signals turn into sympathetic and vagal impulses. The vagal efferents control heart rate and the sympathetic efferents control heart rate, myocardial contractility and peripheral resistance. If there is an increase in blood pressure, then there will be a reflex decrease in the sympathetic activity and an increase in the parasympathetic one. The cardiac cronotropic response to blood pressure variation is very fast-with a delay of one or two beats. The amplitude of the response is a sigmoidal function. The greatest inclination of the response curve, that is to say, the area of greatest variation of the RR interval per unit of pressure, characterises the gain of the baror...
Revista portuguesa de cardiologia : orgão oficial da Sociedade Portuguesa de Cardiologia = Portuguese journal of cardiology : an official journal of the Portuguese Society of Cardiology, 1995
to compare parametric (AR) and non parametric (FFT) spectral analysis results obtained in 512 bea... more to compare parametric (AR) and non parametric (FFT) spectral analysis results obtained in 512 beats series. 104 healthy subjects with normal physical examination and electrocardiogram were studied. The Ecg was recorded at rest, with controlled breathing at 15 cycles/min., and sampled at 300 Hz. The spectral VLF, LF and HF were calculated with FFT algorithm. For the same series, an auto-regressive analysis (AR) with optimized choice of the order of the model (AIC criterion) have been computed, VLF, LF and HF components were identified by AR spectral decomposition. In both groups, athletes and sedentary, there were no statistically differences between VLF, LF, HF and LF/HF spectral indices computed by the two methods. the results suggest that with controlled breathing it does not seems to exist any advantage in the use of AR spectral analysis to compute spectral components of heart rate variability, which is much more laborious that fixed bands non parametric FFT analysis.
Series in Medical Physics and Biomedical Engineering, 2008
Page 72. 3 Intelligent Control Systems in Anesthesia Teresa Feio Mendonça, Catarina Nunes, and Pe... more Page 72. 3 Intelligent Control Systems in Anesthesia Teresa Feio Mendonça, Catarina Nunes, and Pedro Lago CONTENTS 3.1 Introduction..... 54 3.2 Control of Neuromuscular Blockade..... 55 3.2. ...
The electrocardiogram (ECG) is extensively used as a low cost diagnostic tool to provide informat... more The electrocardiogram (ECG) is extensively used as a low cost diagnostic tool to provide information concerning the heart performance. The time interval between consecutive beats in the ECG (tachogram) is the simplest cardiovascular signal to characterize heart rate variability (HRV), in time and frequency domains, and has been applied in various clinical situations (1). This work presents an off-line user
... E-mail The Corresponding Author and Pedro Lago. Departamento de Matemática Aplicada, Faculdad... more ... E-mail The Corresponding Author and Pedro Lago. Departamento de Matemática Aplicada, Faculdade de Ciências da Universidade do Porto, Rua das Taipas 135, 4050 Porto, Portugal. Received 20 June 1997. Available online 9 April 1999. Abstract. A digital PID controller ...
The sensitivity and specificity of heart rate variability (HRV) in the corroboration of brain dea... more The sensitivity and specificity of heart rate variability (HRV) in the corroboration of brain death diagnosis in patients with acute traumatic intracranial lesions was evaluated in 20 patients with clinical criteria of brain death, nine patients in deep coma (Glasgow scale < 7) and 18 normal controls, all age matched. The electrocardiogram was sampled at 650 Hz and several parameters of HRV were calculated, in both time and frequency domains. The HRV parameters were significantly lower in the brain death group compared with the deep coma group. Linear discriminant analysis between brain death and deep coma patients was performed on a data set made of nine randomly selected patients with clinical criteria of brain death and nine patients in deep coma. Cross-validation was performed on the remaining 11 patients with clinical criteria of brain death. All patients in the data set were correctly classified (sensitivity and specificity of 100%). All patients in the cross-validation set were correctly classified (sensitivity of 100%). Further studies are necessary to evaluate the specificity of the method in the independent set of deep coma patients and in the follow-up of comatose and vegetative patients to identify irreversibility of HRV. Nevertheless, these results suggest that HRV analysis constitutes a fully sensitive and specific method for assessing brain death in potential organ donors with acute traumatic lesions of the brain. This fast, quantitative and bedside method seems very promising for the early confirmation of brain death, which is an important factor for the success of transplantation procedures and could have a high predictive value of brain death in comatose patients with brain injuries without fully diagnostic criteria.
Proceedings of the 1998 IEEE International Conference on Control Applications (Cat. No.98CH36104), 1998
... Pedro Lagof, Teresa Mendonqaf*, Lio Gonplves-+ Departamento de Nlatem6tica Aplicada, Faculdad... more ... Pedro Lagof, Teresa Mendonqaf*, Lio Gonplves-+ Departamento de Nlatem6tica Aplicada, Faculdade de CiGncias da Universidade do Port0 ... Abstract A digital PID controller incorporating several modi-fications to accommodate the characteristics of neu-romuscular blockade ...
Revista portuguesa de cardiologia : orgão oficial da Sociedade Portuguesa de Cardiologia = Portuguese journal of cardiology : an official journal of the Portuguese Society of Cardiology, 1997
The aim of this study was to assess the influence of detraining and training on the autonomic con... more The aim of this study was to assess the influence of detraining and training on the autonomic control of heart rate (HR), using time and frequency (spectral analysis) domain components of heart rate variability. Sixteen professional football players (26.7 +/- 3.8 years; 74.9 +/- 4.1 kg; 177 +/- 6.3 cm) were analysed at the end of a 1 month holiday (detraining) and after a 6 week training period (training). HR was recorded over 15 minutes with Holter equipment. The athletes rested in a supine position, in a quiet place and all test were performed between 8 and 10 AM. The subjects were requested to refrain from meals or caffeine for 12 hours before testing. In spite of the high intensity of the training period, there was no significant change in results from detraining condition to training condition. These results can have two possible explanations: (i) the high level of cardiovascular capacity in the detraining trial originated by the recreative physical activity that the players un...
Revista portuguesa de cardiologia : orgão oficial da Sociedade Portuguesa de Cardiologia = Portuguese journal of cardiology : an official journal of the Portuguese Society of Cardiology, 1996
Arterial baroreceptors are sensitive to variation in both blood and pulse pressure. When there is... more Arterial baroreceptors are sensitive to variation in both blood and pulse pressure. When there is an increase in those pressures, the baroreceptors increase the rhythm in which electric impulses are discharged. The impulses are transmitted by the receptors to the nervous centres of the brainstem. Once processed, these signals turn into sympathetic and vagal impulses. The vagal efferents control heart rate and the sympathetic efferents control heart rate, myocardial contractility and peripheral resistance. If there is an increase in blood pressure, then there will be a reflex decrease in the sympathetic activity and an increase in the parasympathetic one. The cardiac cronotropic response to blood pressure variation is very fast-with a delay of one or two beats. The amplitude of the response is a sigmoidal function. The greatest inclination of the response curve, that is to say, the area of greatest variation of the RR interval per unit of pressure, characterises the gain of the baror...
Revista portuguesa de cardiologia : orgão oficial da Sociedade Portuguesa de Cardiologia = Portuguese journal of cardiology : an official journal of the Portuguese Society of Cardiology, 1995
to compare parametric (AR) and non parametric (FFT) spectral analysis results obtained in 512 bea... more to compare parametric (AR) and non parametric (FFT) spectral analysis results obtained in 512 beats series. 104 healthy subjects with normal physical examination and electrocardiogram were studied. The Ecg was recorded at rest, with controlled breathing at 15 cycles/min., and sampled at 300 Hz. The spectral VLF, LF and HF were calculated with FFT algorithm. For the same series, an auto-regressive analysis (AR) with optimized choice of the order of the model (AIC criterion) have been computed, VLF, LF and HF components were identified by AR spectral decomposition. In both groups, athletes and sedentary, there were no statistically differences between VLF, LF, HF and LF/HF spectral indices computed by the two methods. the results suggest that with controlled breathing it does not seems to exist any advantage in the use of AR spectral analysis to compute spectral components of heart rate variability, which is much more laborious that fixed bands non parametric FFT analysis.
Series in Medical Physics and Biomedical Engineering, 2008
Page 72. 3 Intelligent Control Systems in Anesthesia Teresa Feio Mendonça, Catarina Nunes, and Pe... more Page 72. 3 Intelligent Control Systems in Anesthesia Teresa Feio Mendonça, Catarina Nunes, and Pedro Lago CONTENTS 3.1 Introduction..... 54 3.2 Control of Neuromuscular Blockade..... 55 3.2. ...
The electrocardiogram (ECG) is extensively used as a low cost diagnostic tool to provide informat... more The electrocardiogram (ECG) is extensively used as a low cost diagnostic tool to provide information concerning the heart performance. The time interval between consecutive beats in the ECG (tachogram) is the simplest cardiovascular signal to characterize heart rate variability (HRV), in time and frequency domains, and has been applied in various clinical situations (1). This work presents an off-line user
... E-mail The Corresponding Author and Pedro Lago. Departamento de Matemática Aplicada, Faculdad... more ... E-mail The Corresponding Author and Pedro Lago. Departamento de Matemática Aplicada, Faculdade de Ciências da Universidade do Porto, Rua das Taipas 135, 4050 Porto, Portugal. Received 20 June 1997. Available online 9 April 1999. Abstract. A digital PID controller ...
The sensitivity and specificity of heart rate variability (HRV) in the corroboration of brain dea... more The sensitivity and specificity of heart rate variability (HRV) in the corroboration of brain death diagnosis in patients with acute traumatic intracranial lesions was evaluated in 20 patients with clinical criteria of brain death, nine patients in deep coma (Glasgow scale < 7) and 18 normal controls, all age matched. The electrocardiogram was sampled at 650 Hz and several parameters of HRV were calculated, in both time and frequency domains. The HRV parameters were significantly lower in the brain death group compared with the deep coma group. Linear discriminant analysis between brain death and deep coma patients was performed on a data set made of nine randomly selected patients with clinical criteria of brain death and nine patients in deep coma. Cross-validation was performed on the remaining 11 patients with clinical criteria of brain death. All patients in the data set were correctly classified (sensitivity and specificity of 100%). All patients in the cross-validation set were correctly classified (sensitivity of 100%). Further studies are necessary to evaluate the specificity of the method in the independent set of deep coma patients and in the follow-up of comatose and vegetative patients to identify irreversibility of HRV. Nevertheless, these results suggest that HRV analysis constitutes a fully sensitive and specific method for assessing brain death in potential organ donors with acute traumatic lesions of the brain. This fast, quantitative and bedside method seems very promising for the early confirmation of brain death, which is an important factor for the success of transplantation procedures and could have a high predictive value of brain death in comatose patients with brain injuries without fully diagnostic criteria.
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