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    Measuring instantaneous and spectral information entropies by shannon entropy of choi-williams distribution in the context of electroencephalography  Open access

     Melia, Umberto Sergio Pio; Clarià Sancho, Francesc; Vallverdú Ferrer, Montserrat; Caminal Magrans, Pedro
    Entropy: international and interdisciplinary journal of entropy and information studies
    Vol. 16, num. 5, p. 2530-2548
    DOI: 10.3390/e16052530
    Date of publication: 2014-05-01
    Journal article

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    The theory of Shannon entropy was applied to the Choi-Williams time-frequency distribution (CWD) of time series in order to extract entropy information in both time and frequency domains. In this way, four novel indexes were defined: (1) partial instantaneous entropy, calculated as the entropy of the CWD with respect to time by using the probability mass function at each time instant taken independently; (2) partial spectral information entropy, calculated as the entropy of the CWD with respect to frequency by using the probability mass function of each frequency value taken independently; (3) complete instantaneous entropy, calculated as the entropy of the CWD with respect to time by using the probability mass function of the entire CWD; (4) complete spectral information entropy, calculated as the entropy of the CWD with respect to frequency by using the probability mass function of the entire CWD. These indexes were tested on synthetic time series with different behavior (periodic, chaotic and random) and on a dataset of electroencephalographic (EEG) signals recorded in different states (eyes-open, eyes-closed, ictal and non-ictal activity). The results have shown that the values of these indexes tend to decrease, with different proportion, when the behavior of the synthetic signals evolved from chaos or randomness to periodicity. Statistical differences (p-value < 0.0005) were found between values of these measures comparing eyes-open and eyes-closed states and between ictal and non-ictal states in the traditional EEG frequency bands. Finally, this paper has demonstrated that the proposed measures can be useful tools to quantify the different periodic, chaotic and random components in EEG signals. © 2014 by the authors; licensee MDPI, Basel, Switzerland.

    The theory of Shannon entropy was applied to the Choi-Williams time-frequency distribution (CWD) of time series in order to extract entropy information in both time and frequency domains. In this way, four novel indexes were defined: (1) partial instantaneous entropy, calculated as the entropy of the CWD with respect to time by using the probability mass function at each time instant taken independently; (2) partial spectral information entropy, calculated as the entropy of the CWD with respect to frequency by using the probability mass function of each frequency value taken independently; (3) complete instantaneous entropy, calculated as the entropy of the CWD with respect to time by using the probability mass function of the entire CWD; (4) complete spectral information entropy, calculated as the entropy of the CWD with respect to frequency by using the probability mass function of the entire CWD. These indexes were tested on synthetic time series with different behavior (periodic, chaotic and random) and on a dataset of electroencephalographic (EEG) signals recorded in different states (eyes-open, eyes-closed, ictal and non-ictal activity). The results have shown that the values of these indexes tend to decrease, with different proportion, when the behavior of the synthetic signals evolved from chaos or randomness to periodicity. Statistical differences (p-value < 0.0005) were found between values of these measures comparing eyes-open and eyes-closed states and between ictal and non-ictal states in the traditional EEG frequency bands. Finally, this paper has demonstrated that the proposed measures can be useful tools to quantify the different periodic, chaotic and random components in EEG signals. © 2014 by the authors; licensee MDPI, Basel, Switzerland.

  • Multiscale complexity analysis of the cardiac control identifies asymptomatic and symptomatic patients in long QT syndrome type 1

     Bari, Vlasta; Valencia, Jose Fernando; Vallverdú Ferrer, Montserrat; Girardengo, Giulia; Marchi, Andrea; Bassani, Tito; Caminal Magrans, Pedro; Cerutti, Sergio; George Jr, Alfred L.; Brink, Paul A.; Crotti, Lia; Schwartz, Peter J.; Porta, Alberto
    PLoS one
    Vol. 9, num. 4
    DOI: 10.1371/journal.pone.0093808
    Date of publication: 2014-04-04
    Journal article

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    The study assesses complexity of the cardiac control directed to the sinus node and to ventricles in long QT syndrome type 1 (LQT1) patients with KCNQ1-A341V mutation. Complexity was assessed via refined multiscale entropy (RMSE) computed over the beat-to-beat variability series of heart period (HP) and QT interval. HP and QT interval were approximated respectively as the temporal distance between two consecutive R-wave peaks and between the R-wave apex and T-wave end. Both measures were automatically taken from 24-hour electrocardiographic Holter traces recorded during daily activities in non mutation carriers (NMCs, n = 14) and mutation carriers (MCs, n = 34) belonging to a South African LQT1 founder population. The MC group was divided into asymptomatic (ASYMP, n = 11) and symptomatic (SYMP, n = 23) patients according to the symptom severity. Analyses were carried out during daytime (DAY, from 2PM to 6PM) and nighttime (NIGHT, from 12PM to 4AM) off and on beta-adrenergic blockade (BBoff and BBon). We found that the complexity of the HP variability at short time scale was under vagal control, being significantly increased during NIGHT and BBon both in ASYMP and SYMP groups, while the complexity of both HP and QT variability at long time scales was under sympathetic control, being smaller during NIGHT and BBon in SYMP subjects. Complexity indexes at long time scales in ASYMP individuals were smaller than those in SYMP ones regardless of therapy (i.e. BBoff or BBon), thus suggesting that a reduced complexity of the sympathetic regulation is protective in ASYMP individuals. RMSE analysis of HP and QT interval variability derived from routine 24-hour electrocardiographic Holter recordings might provide additional insights into the physiology of the cardiac control and might be fruitfully exploited to improve risk stratification in LQT1 population.

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    Filtering and thresholding the analytic signal envelope in order to improve peak and spike noise reduction in EEG signals  Open access

     Melia, Umberto Sergio Pio; Clarià Sancho, Francesc; Vallverdú Ferrer, Montserrat; Caminal Magrans, Pedro
    Medical engineering and physics
    Vol. 36, num. 4, p. 547-553
    DOI: 10.1016/j.medengphy.2013.11.014
    Date of publication: 2014-04-01
    Journal article

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    To remove peak and spike artifacts in biological time series has represented a hard challenge in the last decades. Several methods have been implemented mainly based on adaptive filtering in order to solve this problem. This work presents an algorithm for removing peak and spike artifacts based on a threshold built on the analytic signal envelope. The algorithm was tested on simulated and real EEG signals that contain peak and spike artifacts with random amplitude and frequency occurrence. The performance of the filter was compared with commonly used adaptive filters. Three indexes were used for testing the performance of the filters: Correlation coefficient (p), mean of coherence function (C), and rate of absolute error (RAE). All these indexes were calculated between filtered signal and original signal without noise. It was found that the new proposed filter was able to reduce the amplitude of peak and spike artifacts with rho > 0.85, C > 0.8, and RAE < 0.5. These values were significantly better than the performance of LMS adaptive filter (rho < 0.85, C < 0.6, and RAE > 1). (C) 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

    To remove peak and spike artifacts in biological time series has represented a hard challenge in the last decades. Several methods have been implemented mainly based on adaptive filtering in order to solve this problem. This work presents an algorithm for removing peak and spike artifacts based on a threshold built on the analytic signal envelope. The algorithm was tested on simulated and real EEG signals that contain peak and spike artifacts with random amplitude and frequency occurrence. The performance of the filter was compared with commonly used adaptive filters. Three indexes were used for testing the performance of the filters: Correlation coefficient (p), mean of coherence function (C), and rate of absolute error (RAE). All these indexes were calculated between filtered signal and original signal without noise. It was found that the new proposed filter was able to reduce the amplitude of peak and spike artifacts with rho > 0.85, C > 0.8, and RAE < 0.5. These values were significantly better than the performance of LMS adaptive filter (rho < 0.85, C < 0.6, and RAE > 1).

  • Serious Games on Heart Failure patients. Estimation of their benefits on the Spanish Health System

     Vallverdú Ferrer, Montserrat; Clarià Sancho, Francesc; Perera Lluna, Alexandre; Domingo Teixidor, Mar; de Antonio Ferrer, Marta; Gomis Román, Pedro; Caminal Magrans, Pedro
    Competitive project

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  • Ischemic risk stratification by means of multivariate analysis of the heart rate variability

     Valencia Murillo, Jose Fernando; Vallverdú Ferrer, Montserrat; Voss, Andreas; Porta, Alberto; Vázquez, Rafael; Caminal Magrans, Pedro; Bayes de Luna, Antonio
    Physiological measurement
    Vol. 34, num. 3, p. 325-338
    DOI: 10.1088/0967-3334/34/3/325
    Date of publication: 2013
    Journal article

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    In this work, a univariate and multivariate statistical analysis of indexes derived from heart rate variability (HRV) was conducted to stratify patients with ischemic dilated cardiomyopathy (IDC) in cardiac risk groups. Indexes conditional entropy, refined multiscale entropy (RMSE), detrended fluctuation analysis, time and frequency analysis, were applied to the RR interval series (beat-to-beat series), for single and multiscale complexity analysis of the HRV in IDC patients. Also, clinical parameters were considered. Two different end-points after a follow-up of three years were considered: (i) analysis A, with 151 survivor patients as a low risk group and 13 patients that suffered sudden cardiac death as a high risk group; (ii) analysis B, with 192 survivor patients as a low risk group and 30 patients that suffered cardiac mortality as a high risk group. A univariate and multivariate linear discriminant analysis was used as a statistical technique for classifying patients in risk groups. Sensitivity (Sen) and specificity (Spe) were calculated as diagnostic criteria in order to evaluate the performance of the indexes and their linear combinations. Sen and Spe values of 80.0% and 72.9%, respectively, were obtained during daytime by combining one clinical parameter and one index from RMSE, and during nighttime Sen = 80% and Spe = 73.4% were attained by combining one clinical factor and two indexes from RMSE. In particular, relatively long time scales were more relevant for classifying patients into risk groups during nighttime, while during daytime shorter scales performed better. The results suggest that the left atrial size, indexed to body surface and RMSE indexes are those that allow enhanced classification of ischemic patients in their respective risk groups, confirming that a single measurement is not enough to fully characterize ischemic risk patients and the clinical relevance of HRV complexity measures.

  • Effect of genetic regions on the correlation between single point mutation variability and morbidity

     Brunel, Helena; Gallardo Chacon, Juan José; Vallverdú Ferrer, Montserrat; Caminal Magrans, Pedro; Perera Lluna, Alexandre
    Computers in biology and medicine
    Vol. 43, num. 5, p. 594-599
    DOI: 10.1016/j.compbiomed.2013.01.017
    Date of publication: 2013-06-01
    Journal article

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    Cross-species sequence comparisons have suggested that cross-species sequence variability is correlated with functionality. The goal of this study was to extend this observation at different genetic regions, focusing on the morbidity of Single Nucleotide Polymorphisms (SNPs). A set of deleterious SNPs was compared to a set of neutral SNPs. Both samples were stratified according to the location of the SNPs at different genetic regions. Deleterious SNPs were observed to be less variable across species than neutral SNPs, these differences being significant for missense mutations (p=1.1×10-9p=1.1×10-9), SNPs in introns (p=6.4×10-3p=6.4×10-3), and SNPs in unknown regions (p=8×10-4p=8×10-4).

  • Short-term vs.long-term heart rate variability in ischemic cardiomyopathy risk stratification

     Voss, Andreas; Schroeder, Rico; Vallverdú Ferrer, Montserrat; Schulz, S; Cygankiewicz, Iwona; Vázquez, Rafael; Bayes de Luna, Antonio; Caminal Magrans, Pedro
    Frontiers in Physiology
    Vol. 4, num. 364, p. 1-15
    DOI: 10.3389/fphys.2013.00364
    Date of publication: 2013-12-13
    Journal article

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    In industrialized countries with aging populations, heart failure affects 0.3-2% of the general population. The investigation of 24 h-ECG recordings revealed the potential of nonlinear indices of heart rate variability (HRV) for enhanced risk stratification in patients with ischemic heart failure (IHF). However, long-term analyses are time-consuming, expensive, and delay the initial diagnosis. The objective of this study was to investigate whether 30 min short-term HRV analysis is sufficient for comparable risk stratification in IHF in comparison to 24 h-HRV analysis. From 256 IHF patients [221 at low risk (IHFLR) and 35 at high risk (IHFHR)] (a) 24 h beat-to-beat time series (b) the first 30 min segment (c) the 30 min most stationary day segment and (d) the 30 min most stationary night segment were investigated. We calculated linear (time and frequency domain) and nonlinear HRV analysis indices. Optimal parameter sets for risk stratification in IHF were determined for 24 h and for each 30 min segment by applying discriminant analysis on significant clinical and non-clinical indices. Long- and short-term HRV indices from frequency domain and particularly from nonlinear dynamics revealed high univariate significances (p < 0.01) discriminating between IHFLR and IHFHR. For multivariate risk stratification, optimal mixed parameter sets consisting of 5 indices (clinical and nonlinear) achieved 80.4% AUC (area under the curve of receiver operating characteristics) from 24 h HRV analysis, 84.3% AUC from first 30 min, 82.2 % AUC from daytime 30 min and 81.7% AUC from nighttime 30 min. The optimal parameter set obtained from the first 30 min showed nearly the same classification power when compared to the optimal 24 h-parameter set. As results from stationary daytime and nighttime, 30 min segments indicate that short-term analyses of 30 min may provide at least a comparable risk stratification power in IHF in comparison to a 24 h analysis period.

  • Heart rate variability analysis in ischemic cardiomyopathy and aortic stenosis patients

     Valencia Murillo, Jose Fernando; Vallverdú Ferrer, Montserrat; Porta, Alberto; Voss, Andreas; Vázquez, Rafael; Caminal Magrans, Pedro
    DOI: 10.1201/b12756-22
    Date of publication: 2013-06-18
    Book chapter

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  • Complexity of the autonomic heart rate control in coronary artery occlusion in patients with and without prior myocardial infarction

     Magrans Nicieza, Rudys; Gomis Román, Pedro; Caminal Magrans, Pedro; Wagner, G.S.
    Medical engineering and physics
    Vol. 35, num. 8, p. 1070-1078
    DOI: 10.1016/j.medengphy.2012.11.004
    Date of publication: 2013-08-01
    Journal article

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    Autonomic nervous system (ANS) is governed by complex interactions arising from feedback loops of nonlinear systems that operate over a wide range of temporal and spatial scales, enabling the organism to adapt to stress, metabolic changes and diseases. This study is aimed to assess multifractal and nonlinear characteristics of the ANS during ischemic events provoked by a prolonged percutaneous coronary intervention (PCI) procedure. Eighty-seven patients from the STAFF III database were used. Patients were classified into 2 groups: (1) with prior myocardial infarction (MI) and (2) without MI (noMI). R¿R signals during three 3-min stages of the procedures were analyzed using multifractal and surrogate data techniques. Multifractal indices increased significantly from the pre-inflation stage to the post-deflation stage. These variations were more marked for the noMI group. Multifractal changes significantly correlated with both the decreased parasympathetic and the increased sympathetic modulations accounted by classical linear indices. Multifractal measures resulted to be a more powerful indicator than linear HRV indices in quantifying the ischemia-induced changes. Right coronary artery (RCA) occlusions provoke greater multifractal reactions throughout the PCI procedure. Our findings suggest reduced complex multifractal and nonlinear reactions of ANS activity in patients with prior MI in comparison to the noMI group, possibly due to degradation in the complexity of control mechanism of heart rate generation

  • SVM-based feature selection to optimize sensitivity¿specificity balance applied to weaning

     Garde Martinez, Ainara; Voss, Andreas; Caminal Magrans, Pedro; Benito Vales, Salvador; Giraldo Giraldo, Beatriz F.
    Computers in biology and medicine
    Vol. 43, num. 5, p. 533-540
    DOI: 10.1016/j.compbiomed.2013.01.014
    Date of publication: 2013
    Journal article

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    Classification algorithms with unbalanced datasets tend to produce high predictive accuracy over the majority class, but poor predictive accuracy over the minority class. This problem is very common in biomedical datamining. This paper introduces a Support Vector Machine (SVM)- based optimized feature selection method, to select the most relevant features and maintain an accurate and well- balanced sensitivity¿specificity result between unbalanced groups. A new metric called the balance index (B) is defined to implement this optimization. The balance index measures the difference between the misclassified data within each class. The proposed optimized feature selection is applied to the classification of patients¿ weaning trials from mechanical ventilation: patients with successful trials who were able to maintain spontaneous breathing after 48h and patients who failed to maintain spontaneous breathing and were reconnected to mechanical ventilation after 30min.

    Classification algorithms with unbalanced data sets tend to produce high predictive accuracy over the majority class, but poor predictive accuracy over the minority class. This problem is very common in biomedical data mining. This paper introduces a Support Vector Machine(SVM)-based optimized features election method, to select the most relevant features and maintain an accurate and well-balanced sensitivity–specificity result between unbalanced groups. A new metric called the balance index(B) is defined to implement this optimization. The balance index measures the difference between the misclassified data within each class. The proposed optimized feature selection is applied to the classification of patients’ weaning trials from mechanical ventilation: patients with successful trials who were able to maintain spontaneous breathing after 48 h and patients who failed to maintain spontaneous breathing and were reconnected to mechanical ventilation after 30min. Patients are characterized through cardiac and respiratory signals, applying joint symbolic dynamic (JSD) analys is to cardiac interbeat and breath durations. First, the most suitable parameters (C þ ,C ,s)are selected to define the appropriate SVM. Then, the features election process is carried out with this SVM, to maintain B lower than 40%. The best result is obtained using 6 features with an accuracy of 80%, a B of 18.64%, a sensitivity of 74.36% and a specificity of 82.42%.

  • Higuchi's fractal complexity of RR and QT interval series during transient myocardial ischemia

     Magrans Nicieza, Rudys; Gomis Román, Pedro; Caminal Magrans, Pedro; Voss, Andreas
    Computing in Cardiology
    p. 421-424
    Presentation's date: 2013-09
    Presentation of work at congresses

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    Myocardial ischemia may lead to significant changes in autonomic control of heart rate (HR) affecting its variability and alter beat-to-beat ventricular repolarization periods. We hypothesized that transient myocardial ischemia affects the complex dynamics of the HR and QT. The aim of this study was to assess the RR and QT interval time series complexity using Higuchi's fractal dimension (HFD) during prolonged balloon occlusion of one of the major coronary arteries.

    Myocardial ischemia may lead to significant changes in autonomic control of heart rate (HR) affecting its variability and alter beat-to-beat ventricular repolarization periods. We hypothesized that transient myocardial ischemia affects the complex dynamics of the HR and QT. The aim of this study was to assess the RR and QT interval time series complexity using Higuchi's fractal dimension (HFD) during prolonged balloon occlusion of one of the major coronary arteries.

  • Characterization of blood pressure signal considering low and high risk stratification in cardiomyopathy patients

     Arcentales Viteri, Andrés Ricardo; Voss, Andreas; Caminal Magrans, Pedro; Bayés Genis, Antoni; Domingo, Maite; Giraldo Giraldo, Beatriz F.
    Computing in Cardiology
    p. 795-798
    Presentation's date: 2013-09
    Presentation of work at congresses

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    Ischemic and dilated cardiomyopathy are associated with disorders of myocardium. Using the blood pressure (BP) signal and the values of the ventricular ejection fraction, we obtained parameters for stratifying cardiomyopathy patients as low- and high-risk. We studied 48 cardiomyopathy patients characterized by NYHA '22: 19 patients with dilated cardiomyopathy (DCM) and 29 patients with ischemic cardiomyopathy (lCM). The left ventricular ejection fraction (LVEF) percentage was used to classify patients in low risk (LR: LVEF > 35%, 17 patients) and high risk (HR: LVEF::; 35%, 31 patients) groups. From the BP signal, we extracted the upward systolic slope (BPsl), the difference between systolic and diastolic BP (B P A), and systolic time intervals (ST I). When we compared the LR and HR groups in the time domain analysis, the best parameters were standard deviation (SD) of 1/ ST I, kurtosis (K) of B Psl, and K of B P A. In the frequency domain analysis, very low frequency (VLF) and high frequency (HF) bands showed statistically significant differences in comaprisons of LR and HR groups. The area under the curve of power spectral density was the best parameter in all classifications, and particularly in the very low- and high- frequency bands (p < 0.001). These parameters could help to improve the risk stratification of cardiomyopathy patients.

    Ischemic and dilated cardiomyopathy are associated with disorders of myocardium. Using the blood pressure (BP) signal and the values of the ventricular ejection fraction, we obtained parameters for stratifying cardiomyopathy patients as low- and high-risk. We studied 48 cardiomyopathy patients characterized by NYHA '22: 19 patients with dilated cardiomyopathy (DCM) and 29 patients with ischemic cardiomyopathy (lCM). The left ventricular ejection fraction (LVEF) percentage was used to classify patients in low risk (LR: LVEF > 35%, 17 patients) and high risk (HR: LVEF::; 35%, 31 patients) groups. From the BP signal, we extracted the upward systolic slope (BPsl), the difference between systolic and diastolic BP (B P A), and systolic time intervals (ST I). When we compared the LR and HR groups in the time domain analysis, the best parameters were standard deviation (SD) of 1/ ST I, kurtosis (K) of B Psl, and K of B P A. In the frequency domain analysis, very low frequency (VLF) and high frequency (HF) bands showed statistically significant differences in comaprisons of LR and HR groups. The area under the curve of power spectral density was the best parameter in all classifications, and particularly in the very low- and high- frequency bands (p < 0.001). These parameters could help to improve the risk stratification of cardiomyopathy patients.

  • Analysis of epileptic EEG signals in children by symbolic dynamics

     Paternoster, Luca; Vallverdú Ferrer, Montserrat; Melia, Umberto Sergio Pio; Voss, Andreas; Caminal Magrans, Pedro; Clarià Sancho, Francesc
    International Conference of the IEEE Engineering in Medicine and Biology Society
    p. 4362-4365
    DOI: 10.1109/EMBC.2013.6610512
    Presentation's date: 2013-07-03
    Presentation of work at congresses

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    Epilepsy is one of the most prevalent neurological disorders among children. The study of surface EEG signals in patients with epilepsy by techniques based on symbolic dynamics can provide new insights into the epileptogenic process and may have considerable utility in the diagnosis and treatment of epilepsy. The goal of this work was to find patterns from a methodology based on symbolic dynamics to characterize seizures on surface EEG in pediatric patients with intractable epilepsy. A total of 76 seizures were analyzed by their pre-ictal, ictal and post-ictal phases. An analytic signal envelope algorithm was applied to each EEG segment and its performance was evaluated. Several variables were defined from the distribution of words constructed on the EEG transformed into symbols. The results showed strong evidences of detectable non-linear changes in the EEG dynamics from pre-ictal to ictal phase and from ictal to post-ictal phase, with an accuracy higher than 70%.

  • Auto-mutual information function for predicting pin responses in EEG signals during sedation

     Melia, Umberto Sergio Pio; Vallverdú Ferrer, Montserrat; Jospin, Matieu; Jensen, Erik W.; Valencia, J.F.; Clarià, Francesc; Gambus, Pedro L.; Caminal Magrans, Pedro
    Mediterranean Conference on Medical and Biological Engineering and Computing
    p. 623-626
    DOI: 10.1007/978-3-319-00846-2_154
    Presentation's date: 2013-09-25
    Presentation of work at congresses

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    The level of sedation in patients undergoing medical procedures evolves continuously, such as the effect of the anesthetic and analgesic agents is counteracted by pain stimuli. The monitors of depth of anesthesia, based on the analysis of the electroencephalogram (EEG), have been progressively introduced into the daily practice to provide additional information about the state of the patient. However, the quantification of analgesia still remains an open problem. The purpose of this work was to analyze the capability of prediction of nociceptive responses based on the auto-mutual information function (AMIF). AMIF measures were calculated on EEG signal in order to predict the presence or absence of the nociceptive responses to endoscopy tube insertion during sedation in endoscopy procedure. Values of prediction probability of Pk above 0.80 and percentages of sensitivity and specificity above 70% and 70% respectively were achieved combining AMIF with power spectral density and concentrations of remifentanil.

  • Higuchi¿s fractal complexity of RR and QT interval eeries during transient myocardial ischemia

     Magrans Nicieza, Rudys; Gomis Román, Pedro; Caminal Magrans, Pedro; Voss, Andreas
    Computing in Cardiology
    p. 421-424
    Presentation's date: 2013-09-24
    Presentation of work at congresses

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    Myocardial ischemia may lead to significant changes in autonomic control of heart rate (HR) affecting its variability and alter beat-to-beat ventricular repolarization periods. We hypothesized that transient myocardial ischemia affects the complex dynamics of the HR and QT. The aim of this study was to assess the RR and QT interval time series complexity using Higuchi¿s fractal dimension (HFD) during prolonged balloon occlusion of one of the major coronary arteries. Eighty-five patients who underwent elective percutaneous coronary intervention procedures were selected. Patients were classified into 2 groups according to the presence of prior healed myocardial infarction (INF) (n = 29) or not (No_INF) (n = 56). RR, QT and QTc (Bazzet¿s formula) time series were obtained from continuous ECG. Three 3-minute stages were chosen: (1) preinflation as baseline (pre), (2) from the start of occlusion (pci), and (3) immediately post deflation (post_pci). HFD was calculated on each 3-minute stage time series to quantify the changing complexity and self-similarity of RR, QT and QTc time series (HFD RR, HFD QT and HFD QTc, respectively). Cohen¿s d statistics were included to measure the effect size of the procedure. HFD values decreased significantly from baseline to pci and post_pci in the three time-series. HFD RR, 1.76 ± 0.13 vs. 1.69 ± 0.15 (p<0.001, Cohen¿s d = -0.64); HFD QT, 1.90 ± 0.11 vs 1.82 ± 0.13 (p<0.001, d = -0.67); HFD QTc, 1.88 ± 0.09 vs. 1.83 ± 0.11 (p<0.01, d= -0.46). The HFD reduction was greater from baseline to post_pci (p<0.001, d = -0.99 (RR), d = -1.02 (QT)). HFD of QT intervals decreases during the procedure predominantly in the No_INF group. The time series studied, related to autonomic control of HR and to the variability of ventricular repolarization, exhibit a reduced complexity provoked by transient myocardial ischemia.

  • Coherence between respiratory flow signal and heart rate variability applied to classify weaning trials patients

     Arcentales Viteri, Andrés Ricardo; Giraldo Giraldo, Beatriz F.; Caminal Magrans, Pedro; Benito Vales, Salvador
    IBEC Symposium on Bioengineering and Nanomedicine
    Presentation's date: 2013-05-05
    Presentation of work at congresses

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  • Refined multiscale entropy analysis of heart period and QT interval variabilities in long QT syndrome type-1 patients

     Bari, Vlasta; Vallverdú Ferrer, Montserrat; Valencia, Jose Fernando; Girardengo, Giulia; Bassani, Tito; Marchi, Andrea; Calvillo, L.; Caminal Magrans, Pedro; Cerutti, Sergio; Brink, Paul A.; Crotti, Lia; Schwartz, Peter J.; Porta, A.
    International Conference of the IEEE Engineering in Medicine and Biology Society
    p. 5554-5557
    Presentation's date: 2013-07-03
    Presentation of work at congresses

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    This study assesses complexity of cardiovascular control in patients affected by type-1 variant of long QT (LQT1) syndrome. Complexity was assessed by refined multiscale entropy of heart period (HP) and QT interval variabilities. HP was taken as the time distance between two consecutive R peaks (RR) and QT interval was approximated as the time distance between the R-peak and T-wave apex (RTa) and between R-peak and T-wave end (RTe). RR, RTa and RTe intervals were automatically extracted from 24h Holter recordings and the daytime period was analyzed (from 02:00 to 06:00 PM). Non mutation carrier (NMC) individuals (n=11), utilized as a control group, were taken from the same family line of the mutation carrier (MC) subjects (n=26). We found that, while NMC and MC groups were indistinguishable based on time domain and complexity analyses of RR dynamics, complexity analysis of RTa and RTe variabilities clearly separates the two populations and suggests an impairment in the cardiac control mechanisms acting on the ventricles.

  • Characterization of the respiratory pattern variability of patients with different pressure support levels

     Giraldo Giraldo, Beatriz F.; Chaparro Preciado, Javier; Caminal Magrans, Pedro; Benito Vales, Salvador
    IEEE Engineering in Medicine and Biology Society
    p. 3849-3852
    DOI: 10.1109/EMBC.2013.6610384
    Presentation's date: 2013-07-03
    Presentation of work at congresses

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    One of the most challenging problems in intensive care is still the process of discontinuing mechanical ventilation, called weaning process. Both an unnecessary delay in the discontinuation process and a weaning trial that is undertaken too early are undesirable. In this study, we analyzed respiratory pattern variability using the respiratory volume signal of patients submitted to two different levels of pressure support ventilation (PSV), prior to withdrawal of the mechanical ventilation. In order to characterize the respiratory pattern, we analyzed the following time series: inspiratory time, expiratory time, breath duration, tidal volume, fractional inspiratory time, mean inspiratory flow and rapid shallow breathing. Several autoregressive modeling techniques were considered: autoregressive models (AR), autoregressive moving average models (ARMA), and autoregressive models with exogenous input (ARX). The following classification methods were used: logistic regression (LR), linear discriminant analysis (LDA) and support vector machines (SVM). 20 patients on weaning trials from mechanical ventilation were analyzed. The patients, submitted to two different levels of PSV, were classified as low PSV and high PSV. The variability of the respiratory patterns of these patients were analyzed. The most relevant parameters were extracted using the classifiers methods. The best results were obtained with the interquartile range and the final prediction errors of AR, ARMA and ARX models. An accuracy of 95% (93% sensitivity and 90% specificity) was obtained when the interquartile range of the expiratory time and the breath duration time series were used a LDA model. All classifiers showed a good compromise between sensitivity and specificity. © 2013 IEEE.

  • Characterization of patients with different ventricular ejection fractions using blood pressure signal analysis

     Arcentales Viteri, Andrés Ricardo; Voss, Andreas; Caminal Magrans, Pedro; Bayés Genis, Antoni; Domingo, Mar Teresa; Giraldo Giraldo, Beatriz F.
    Computing in Cardiology
    p. 795-798
    Presentation's date: 2013-09
    Presentation of work at congresses

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    Ischemic and dilated cardiomyopathy are associated with disorders of myocardium. Using the blood pressure (BP) signal and the values of the ventricular ejection fraction, we obtained parameters for stratifying cardiomyopathy patients as low- and high-risk. We studied 48 cardiomyopathy patients characterized by NYHA =2: 19 patients with dilated cardiomyopathy (DCM) and 29 patients with ischemic cardiomyopathy (ICM). The left ventricular ejection fraction (LVEF) percentage was used to classify patients in low risk (LR: LVEF > 35%, 17 patients) and high risk (HR: LVEF = 35%, 31 patients) groups. From the BP signal, we extracted the upward systolic slope (BP sl), the difference between systolic and diastolic BP (BPA), and systolic time intervals (STI). When we compared the LR and HR groups in the time domain analysis, the best parameters were standard deviation (SD) of 1=STI, kurtosis (K) of BPsl, and K of BPA. In the frequency domain analysis, very low frequency (VLF) and high frequency (HF) bands showed statistically significant differences in comaprisons of LR and HR groups. The area under the curve of power spectral density was the best parameter in all classifications, and particularly in the very-low-and high- frequency bands (p < 0.001). These parameters could help to improve the risk stratification of cardiomyopathy patients.

    Ischemic and dilated cardiomyopathy are associated with disorders of myocardium. Using the blood pressure (BP) signal and the values of the ventricular ejection fraction, we obtained parameters for stratifying cardiomyopathy patients as low- and high-risk. We studied 48 cardiomyopathy patients characterized by NYHA =2: 19 patients with dilated cardiomyopathy (DCM) and 29 patients with ischemic cardiomyopathy (ICM). The left ventricular ejection fraction (LVEF) percentage was used to classify patients in low risk (LR: LVEF > 35%, 17 patients) and high risk (HR: LVEF = 35%, 31 patients) groups. From the BP signal, we extracted the upward systolic slope (BP sl), the difference between systolic and diastolic BP (BPA), and systolic time intervals (STI). When we compared the LR and HR groups in the time domain analysis, the best parameters were standard deviation (SD) of 1=STI, kurtosis (K) of BPsl, and K of BPA. In the frequency domain analysis, very low frequency (VLF) and high frequency (HF) bands showed statistically significant differences in comaprisons of LR and HR groups. The area under the curve of power spectral density was the best parameter in all classifications, and particularly in the very-low-and high- frequency bands (p < 0.001). These parameters could help to improve the risk stratification of cardiomyopathy patients.

  • Prediction of nociceptive responses during sedation by time-frequency representation

     Melia, Umberto Sergio Pio; Vallverdú Ferrer, Montserrat; Jospin, Mathieu; Jensen, Erik W.; Valencia, Jose Fernando; Clarià, Francesc; Gambus, Pedro L.; Caminal Magrans, Pedro
    International Conference of the IEEE Engineering in Medicine and Biology Society
    p. 2547-2550
    DOI: 10.1109/EMBC.2013.6610059
    Presentation's date: 2013-07-03
    Presentation of work at congresses

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    The level of sedation in patients undergoing medical procedures evolves continuously, such as the effect of the anesthetic and analgesic agents is counteracted by pain stimuli. The monitors of depth of anesthesia, based on the analysis of the electroencephalogram (EEG), have been progressively introduced into the daily practice to provide additional information about the state of the patient. However, the quantification of analgesia still remains an open problem. The purpose of this work is to analyze the capability of prediction of nociceptive responses based on the time-frequency representation (TFR) of EEG signal. Functions of spectral entropy, instantaneous power and instantaneous frequency were calculated in order to predict the presence or absence of the nociceptive responses to different stimuli during sedation in endoscopy procedure. Values of prediction probability of Pk above 0.75 and percentages of sensitivity and specificity above 70% and 65% respectively were achieved combining TFR functions with bispectral index (BIS) and with concentrations of propofol (CeProp) and remifentanil (CeRemi).

    The level of sedation in patients undergoing medical procedures evolves continuously, such as the effect of the anesthetic and analgesic agents is counteracted by pain stimuli. The monitors of depth of anesthesia, based on the analysis of the electroencephalogram (EEG), have been progressively introduced into the daily practice to provide additional information about the state of the patient. However, the quantification of analgesia still remains an open problem. The purpose of this work is to analyze the capability of prediction of nociceptive responses based on the time-frequency representation (TFR) of EEG signal. Functions of spectral entropy, instantaneous power and instantaneous frequency were calculated in order to predict the presence or absence of the nociceptive responses to different stimuli during sedation in endoscopy procedure. Values of prediction probability of Pk above 0.75 and percentages of sensitivity and specificity above 70% and 65% respectively were achieved combining TFR functions with bispectral index (BIS) and with concentrations of propofol (CeProp) and remifentanil (CeRemi).

  • Análisis espectral no lineal del EEG de niños con epilepsia intratable

     Portolés, oscar; Schroeder, Rico; Vallverdú Ferrer, Montserrat; Voss, Andreas; Caminal Magrans, Pedro
    Jornadas de Automàtica
    p. 123-130
    Presentation's date: 2013-09-04
    Presentation of work at congresses

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    Non-linear dynamic analysis of RR signals in patients with and without excessive daytime sleepiness  Open access

     Melia, Umberto Sergio Pio; Guaita, Marc; Vallverdú Ferrer, Montserrat; Clarià Sancho, Francesc; Caminal Magrans, Pedro; Embid, Cristina; Vilaseca, Isabel; Salamero, Manuel; Santamaria, J.
    Computing in Cardiology
    p. 449-452
    Presentation's date: 2013-09-22
    Presentation of work at congresses

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    Linear and non-linear measures applied to heart rate variability (HRV) can be used to quantify modulation of the sympathetic and parasympathetic branches of the autonomic nervous system. RR signals were obtained from the ECG recorded during five Maintenance of Wakefulness (MWT) and Multiple Sleep Latency (MSLT) tests alternated throughout the day from patients suffering sleep disturbance. Two different end-points were considered: Study A, excessive daytime sleepiness (EDS) versus without daytime sleepiness (WDS); Study B, Pre-CPAP versus Post-CP AP (continuous positive airway pressure therapy) in EDS. Measures obtained from spectral analysis (PSD), time-frequency representation (TFR), auto-correntropy (ACORR) and auto-mutual-information function (AMIF) were applied to describe autonomic nervous system activity and RR regularity. Statistical differences between EDS and WDS groups were found in MSLT events. During MSLT, the parasympathetic activity and RR regularity in EDS were affected by CPAP therapy. Non-linear measures obtained from EDS in Post-CPAP differed from Pre-CPAP (p-value<0.05) and tended to be similar to WDS.

    Linear and non-linear measures applied to heart rate variability (HRV) can be used to quantify modulation of the sympathetic and parasympathetic branches of the autonomic nervous system. RR signals were obtained from the ECG recorded during five Maintenance of Wakefulness (MWT) and Multiple Sleep Latency (MSLT) tests alternated throughout the day from patients suffering sleep disturbance. Two different end-points were considered: Study A, excessive daytime sleepiness (EDS) versus without daytime sleepiness (WDS); Study B, Pre-CPAP versus Post-CP AP (continuous positive airway pressure therapy) in EDS. Measures obtained from spectral analysis (PSD), time-frequency representation (TFR), auto-correntropy (ACORR) and auto-mutual-information function (AMIF) were applied to describe autonomic nervous system activity and RR regularity. Statistical differences between EDS and WDS groups were found in MSLT events. During MSLT, the parasympathetic activity and RR regularity in EDS were affected by CPAP therapy. Non-linear measures obtained from EDS in Post-CPAP differed from Pre-CPAP (p-value<0.05) and tended to be similar to WDS.

  • Automatic Quality Control of Forced Spirometry

     Burgos Rincón, Felip; Roca Torrent, Josep; Melia, Umberto Sergio Pio; Vallverdú Ferrer, Montserrat; Caminal Magrans, Pedro; LLuch Ariet, Magi; Velickosvski, Felip
    Date of request: 2013-09-10
    Invention patent

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  • Assessment of autonomic control of the heart during transient myocardial ischemia

     Gomis Román, Pedro; Caminal Magrans, Pedro; Vallverdú Ferrer, Montserrat; Warren, Stafford G; Stein, P.K; Wagner, Galen
    Journal of electrocardiology
    Vol. 45, num. 1, p. 82-89
    DOI: 10.1016/j.jelectrocard.2011.08.013
    Date of publication: 2012-01
    Journal article

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  • Long-term versus short-term heart rate variability analyses for risk stratification in ischemic heart failure patients

     Schroeder, Rico; Caminal Magrans, Pedro; Vallverdú Ferrer, Montserrat; Brunel, Helena; Cygankiewicz, Iwona; Vázquez García, R.; Bayes de Luna, Antonio; Voss, Andreas
    Biomedizinische technik
    Vol. 57, p. 4315-4325
    DOI: 10.1515/bmt-2012-4315
    Date of publication: 2012
    Journal article

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  • High quality spirometry across the healthcare system

     Burgos, Felip; Vallverdú Ferrer, Montserrat; Galdiz, B.; Gallego, C.; Castillo Villegas, Diego; Ayza, Jordi; Caminal Magrans, Pedro; Escarrabill, J.; Roca, J.
    American journal of respiratory and critical care medicine
    Vol. 185, p. A5160-A5170
    Date of publication: 2012
    Journal article

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  • Choi-Williams distribution to describe coding and non-coding regions in primary transcript pre-mRNA

     Melia, U.; Vallverdú Ferrer, Montserrat; Clarià Sancho, Francesc; Gallardo Chacon, Joan Josep; Perera Lluna, Alexandre; Caminal Magrans, Pedro
    Journal of Medical and Biological Engineering
    p. 1-33
    DOI: 10.5405/jmbe.1060
    Date of publication: 2012-05-28
    Journal article

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  • Analysis of roots in ARMA model for the classification of patients on weaning trials

     Giraldo Giraldo, Beatriz F.; Gaspar, Benjamín W.; Caminal Magrans, Pedro; Benito Vales, Salvador
    IEEE Engineering in Medicine and Biology Society
    p. 698-701
    Presentation's date: 2012-09
    Presentation of work at congresses

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  • Performance of respiratory pattern parameters in classifiers for predict weaning process

     Chaparro Preciado, Javier; Giraldo Giraldo, Beatriz F.; Caminal Magrans, Pedro; Benito Vales, Salvador
    IEEE Engineering in Medicine and Biology Society
    p. 4349-4352
    Presentation's date: 2012-09
    Presentation of work at congresses

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    Symbolic dynamics of QT interval series in ischemic cardiomyopathy  Open access

     Cuponne, Anna; Vallverdú Ferrer, Montserrat; Gomis Román, Pedro; Porta, Alberto; Voss, Andreas; Bayes de Luna, Antonio; Caminal Magrans, Pedro
    Computing in Cardiology
    p. 617-620
    Presentation's date: 2012-09-11
    Presentation of work at congresses

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    Repolarization dynamics may be of increasing interest in analyzing ECG-Holter for characterization of myocardial ischemic events related to cardiac death. The quantification of the dynamics of the beat-to-beat QT interval fluctuations, representing changes in repolarization duration, may be another emerging marker of cardiac events. Based on these arguments, we propose a symbolic analysis series to quantify the dynamics of the beat-to-beat QT interval fluctuations, representing changes in repolarization duration, and the prevalence of sympathetic or parasympathetic cardiac modulation in the RR series. This analysis decomposes the series in patterns of length L=3 beat and classify them into three categories: non-variable, variable, and very variable patterns referred to as P0, P1 and P2 patterns. The present work analyses QT and RR series obtained from 24-hour ECG-Holter recordings in order to obtained patterns able to stratify high (HRG) and low risk (LRG) of suffer cardiac mortality in patients with symptomatic myocardial ischemia. Comparing LRG and HRG, results showed that pattern P0 could better quantify QT series and pattern P2 the RR series. These findings suggest a decreased cardiac vagal function with a relative increase in sympathetic cardiac modulation, and more complex pattern of ventricular repolarization in the HRG.

    Repolarization dynamics may be of increasing interest in analyzing ECG-Holter for characterization of myocardial ischemic events related to cardiac death. The quantification of the dynamics of the beat-to-beat QT interval fluctuations, representing changes in repolarization duration, may be another emerging marker of cardiac events. Based on these arguments, we propose a symbolic analysis series to quantify the dynamics of the beat-to-beat QT interval fluctuations, representing changes in repolarization duration, and the prevalence of sympathetic or parasympathetic cardiac modulation in the RR series. This analysis decomposes the series in patterns of length L=3 beat and classify them into three categories: non-variable, variable, and very variable patterns referred to as P0, P1 and P2 patterns. The present work analyses QT and RR series obtained from 24-hour ECG-Holter recordings in order to obtained patterns able to stratify high (HRG) and low risk (LRG) of suffer cardiac mortality in patients with symptomatic myocardial ischemia. Comparing LRG and HRG, results showed that pattern P0 could better quantify QT series and pattern P2 the RR series. These findings suggest a decreased cardiac vagal function with a relative increase in sympathetic cardiac modulation, and more complex pattern of ventricular repolarization in the HRG.

  • Removal of peak and spike noise in EEG signals based on the analytic signal magnitude

     Melia, U.; Clarià, Francesc; Vallverdú Ferrer, Montserrat; Caminal Magrans, Pedro
    IEEE Engineering in Medicine and Biology Society
    p. 3523-3526
    DOI: 10.1109/EMBC.2012.6346726
    Presentation's date: 2012
    Presentation of work at congresses

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  • Validation of the qCO cardiac output monitor during Valsalva maneuver

     Jospin, Mathieu; Aguilar, J.P.; Gambus, Pedro L.; Jensen, Erik W.; Vallverdú Ferrer, Montserrat; Caminal Magrans, Pedro
    IEEE Engineering in Medicine and Biology Society
    p. 240-243
    DOI: 10.1109/EMBC.2012.6345914
    Presentation's date: 2012
    Presentation of work at congresses

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    Monitoring cardiac output for a variety of patient conditions is essential to ensure tissue perfusion and oxygenation. Cardiac output can be measured either invasively using a pulmonary artery catheter or non-invasively using impedance cardiography (ICG). The objective of the present study was to validate a cardiac output monitor, the qCO (Quantium Medical, Barcelona, Spain). The qCO is based on the ICG principle. Twenty-five volunteers (18-75 years) were enrolled in the study. The duration of the study was 10 min. The subjects were asked to rest quietly in an armchair for a duration of 5 min. At 5 min they were asked to do a Valsalva maneuver which is known to decrease the cardiac output. The baseline value of the normalized cardiac output (qCO index) was compared with the minimum value during the Valsalva maneuver. The results showed (t-test, p<0.0005) significant difference between the cardiac output estimated at baseline and during the Valsalva maneuver. In conclusion, the qCO was able to indicate trend changes of the cardiac output in volunteers.

  • Network-based enrichment analysis of gene expression through protein-protein interaction data

     Massanet Vila, Raimon Jaume; Fernandez Albert, Francesc; Perera Lluna, Alexandre; Caminal Magrans, Pedro
    IEEE Engineering in Medicine and Biology Society
    p. 6317-6320
    DOI: 10.1109/EMBC.2012.6347438
    Presentation's date: 2012-09-01
    Presentation of work at congresses

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    High-throughput analysis of gene expression data is subject to technological and statistical issues that confuse the underlying expression-condition associations. In this contribution a network-based candidate gene prioritization strategy was applied to the enrichment of a publicly available gene expression dataset, focused on the study of the mechanosensitivity of genes exposed to altered pulmonary matrix stiffness. Results suggested that some genes which had not been taken into account in the original study could have an important role in the processes causing, or affected by, pulmonary fibrosis.

  • Long-term versus short-term heart rate variability analyses for risk stratification in ischemic heart failure patients

     Schroeder, Rico; Caminal Magrans, Pedro; Vallverdú Ferrer, Montserrat; Brunel, Helena; Cygankiewicz, I.; Vázquez García, R.; Bayes de Luna, Antonio; Voss, Andreas
    Annual Conference of the German Society for Biomedical Engineering
    DOI: 10.1515/bmt-2012-4315
    Presentation of work at congresses

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  • High quality spirometry across the healthcare system

     Burgos, Felip; Vallverdú Ferrer, Montserrat; Galdiz, B; Gallego, C.; Castillo Villegas, Diego; Ayza, Jordi; Caminal Magrans, Pedro; Escarrabill, J.; Roca, J.
    American Thorathic Spirometry Conference
    p. A5160
    Presentation's date: 2012
    Presentation of work at congresses

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  • Effect of acute myocardial ischemia on different frequency bandwidths and temporal regions of the QRS

     Gomis Román, Pedro; Caminal Magrans, Pedro; Wagner, G.S.
    STAFF Symposium
    Presentation's date: 2012-09-14
    Presentation of work at congresses

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  • Comportamiento de parámetros del patrón respiratorio en clasificadores para la predicción del proceso weaning

     Chaparro Preciado, Javier; Giraldo Giraldo, Beatriz F.; Caminal Magrans, Pedro; Benito Vales, Salvador
    Congreso Anual de la Sociedad Española de Ingeniería Biomédica
    p. 1-4
    Presentation's date: 2012-11
    Presentation of work at congresses

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  • Non-linear measures and time-frequency representation of electroencephalogram containing auditory and nociceptive stimuli responses

     Melia, Umberto Sergio Pio; Vallverdú Ferrer, Montserrat; Clarià Sancho, Francesc; Valls-Solé, Josep; Caminal Magrans, Pedro
    International Workshop on Biosignal Interpretation
    p. 153-156
    Presentation's date: 2012-07-03
    Presentation of work at congresses

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  • Herramientas de procesado de señal y bioinformática para la evaluación multinivel de desórdenes cardiovasculares y monitorización

     Gomis Román, Pedro; Vallverdú Ferrer, Montserrat; Caminal Magrans, Pedro; Magrans Nicieza, Rudys
    Competitive project

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  • CAMPUS EXCELENCIA INTERN

     Caminal Magrans, Pedro
    Competitive project

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    Cuantificación de la recurrencia en el estudio de la variabilidad del ritmo cardiaco y la duración del ciclo respiratorio en pacientes en proceso de extubación  Open access

     Arcentales Viteri, Andrés Ricardo; Giraldo Giraldo, Beatriz F.; Caminal Magrans, Pedro; Benito Vales, Salvador; Voss, Andreas
    Congreso Anual de la Sociedad Española de Bioingeniería
    p. 471-474
    Presentation's date: 2011-11
    Presentation of work at congresses

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    El sistema nervioso autónomo regula el comportamiento de los sistemas cardiaco y respiratorio. Su evaluación durante la retirada de la ventilación mecánica puede proporcionar información sobre el comportamiento cardiorespiratorio de los pacientes. Este trabajo propone el análisis de la variabilidad del ritmo cardiaco (HRV) y la duración del ciclo respiratorio (TTot) aplicando la técnica ‘Recurrence Plot (RP)’ y su interacción ‘Joint Recurrence Plot (JRP)’. Se han analizado 131 pacientes, asistidos mediante ventilación mecánica, en proceso de extubación: 92 pacientes con éxito en la extubación (grupo E) y 39 pacientes que no pudieron mantener la respiración espontánea y fracasaron en la extubación (grupo F). Obtenida la matriz de recurrencia para cada señal, se calcularon parámetros que permitían cuantificar la recurrencia de éstas. Los resultados muestran que parámetros como el determinismo (DET), la duración media de la línea diagonal (L), y la entropía (ENTR), presentaron diferencias estadísticamente significativas aplicando RP en las series TTot, pero no en HRV. Al comparar la interacción entre los grupos con JRP, todos los parámetros han sido relevantes. En todos los casos, valores medios del análisis de la cuantificación de recurrencia es mayor en el grupo E que en el grupo F. Las principales diferencias entre los grupos se encuentran en las estructuras diagonales y verticales de la recurrencia conjunta.

  • A COMPUTATIONAL DISTRIBUTED SYSTEM TO SUPPORT THE TREATMENT OF PATIENTS WITH MAJOR DEPRESSION

     Rosell Ferrer, Francisco Javier; Caminal Magrans, Pedro; Ramos Castro, Juan Jose; Garcia Gonzalez, Miquel Angel; Mahdavi, Hadiseh
    Competitive project

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  • Characterization of the cerebral activity by time¿frequency representation of evoked EEG potentials

     Clarià, Francesc; Vallverdú Ferrer, Montserrat; Riba, J; Romero Lafuente, Sergio; Caminal Magrans, Pedro
    Physiological measurement
    Vol. 32, num. 8, p. 1327-1346
    DOI: 10.1088/0967-3334/32/8/021
    Date of publication: 2011-07-15
    Journal article

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  • Recurrence quantification analysis of heart rate variability and respiratory flow series in patients on weaning trials

     Arcentales Viteri, Andrés Ricardo; Giraldo Giraldo, Beatriz F.; Caminal Magrans, Pedro; Benito Vales, Salvador; Voss, Andreas
    IEEE Engineering in Medicine and Biology Society
    p. 2724-2727
    DOI: 10.1109/IEMBS.2011.6090747
    Presentation's date: 2011-09
    Presentation of work at congresses

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  • Effect of acute myocardial ischemia on different high-frequency bandwidths and temporal regions of the QRS

     Magrans Nicieza, Rudys; Gomis Román, Pedro; Voss, Andreas; Caminal Magrans, Pedro
    IEEE Engineering in Medicine and Biology Society
    p. 7083-7086
    Presentation's date: 2011-09-03
    Presentation of work at congresses

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    The purpose of this study was to describe the changes in high-frequency QRS (HF-QRS) components due to myocardial ischemia provoked by prolonged artery occlusion during percutaneous coronary interventions (PCI). Signalaveraged ECGs from 69 patients were obtained during PCI procedures and comparison of high-frequency components of the QRS at different temporal regions and frequency bandwidth were performed. Continuous wavelet transform was applied to estimate the energy contents over the studied timefrequency regions. Seven frequency bands from 50 to 300 Hz, with bandwidth = 100 Hz were considered. The sum of all 12 leads energy decreased significantly (p < 0.001) from pre-PCI to PCI during both second half and total QRS complex in all frequency bands, but the main effect was found in the 200-300 Hz band. The energy changes were more marked toward higher frequency bands. The second half of QRS complex was more sensitive to changes due to myocardial ischemia.

  • Algoritmo de búsqueda de secuencias cis-regulatorias basado en el análisis del incremento de la información mediante la divergencia de Rényi

     Maynou Fernández, Joan; Vallverdú Ferrer, Montserrat; Caminal Magrans, Pedro; Perera Lluna, Alexandre
    Congreso Anual de la Sociedad Española de Bioingeniería
    p. 167-170
    Presentation's date: 2011-11-17
    Presentation of work at congresses

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  • Analysis of incomplete gene expression dataset through protein-protein interaction information

     Massanet Vila, Raimon Jaume; Padró Capmany, Teresa; Cardús, Anna; Badimón, Lina; Caminal Magrans, Pedro; Perera Lluna, Alexandre
    IEEE Engineering in Medicine and Biology Society
    p. 6845-6848
    DOI: 10.1109/IEMBS.2011.6091688
    Presentation's date: 2011
    Presentation of work at congresses

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    This paper shows a graph based method to analyze proteomic expression data. The method allows the prediction of the expression of genes not measured by the gene expression technology based on the local connectivity properties of the measured differentially expressed gene set. The prediction of the expression jointly with the stability of this prediction as a function of the variation of the initial expressed set is computed. The method is able to correctly predict one third of the proteins with independence of variations on the selection of the initial set. The algorithm is validated through a Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometer (MALDI-TOF) protein expression experiment aiming the study of the protein expression patterns and post-translational modifications in human endothelial vascular cells exposed to atherosclerotic levels of Low Density Lipoproteins (LDL).

  • Access to the full text
    Caracterización y análisis de las interacciones de regulación entre los factores de transcripción y los genes  Open access

     Maynou Fernández, Joan; Pairó Castiñeira, Erola; Massanet Vila, Raimon Jaume; Vallverdú Ferrer, Montserrat; Caminal Magrans, Pedro; Perera Lluna, Alexandre
    Congreso Anual de la Sociedad Española de Bioingeniería
    p. 1-4
    Presentation's date: 2011-11-17
    Presentation of work at congresses

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    El estudio y la comprensión de las redes de interacción entre proteínas es fundamental para entender el funcionamiento de los diferentes procesos biológicos a nivel celular. El conjunto de interacciones entre proteínas, definido como interactoma, es muy complejo debido al número y a los diferentes tipos de interacciones existentes. En este contexto, estudiar las interacciones de regulación entre proteína y ácido desoxirribonucleico (Factor de Transcripción -ADN) es importante para comprender el nivel de expresión de los genes afectados. El principal objetivo de este trabajo es la caracterización desde el punto de vista estadístico de los factores de transcripción que regulan un gen y de los genes regulados por un factor de transcripción. Los datos han sido obtenidos de la base de datos String 1 y de la aplicación de minería de datos de SabioSciences 2. El trabajo se centra en las interacciones de regulación TF-gen para el organismo Homo sapiens.

    Postprint (author’s final draft)

  • Improving quality control of forced spirometry: A new algorithm for automatic evaluation

     Burgos, F.; Melia, U.; Vallverdú Ferrer, Montserrat; Caminal Magrans, Pedro; Roca, J.
    American Thoracic Society International Conference
    p. p. A3127-
    Presentation's date: 2011-05-13
    Presentation of work at congresses

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  • Indices of segmented symbolic dynamics as risk markers in ischemic heart failure patients

     Schroeder, Rico; Caminal Magrans, Pedro; Vallverdú Ferrer, Montserrat; Brunel Montaner, Helena; Cygankiewicz, I.; Vázquez García, R.; Bayes de Luna, Antonio; Voss, Andreas
    Biomedizinische Technik
    p. P162-
    Presentation's date: 2011
    Presentation of work at congresses

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