Montserrat Vallverdu - Academia.edu (original) (raw)
Papers by Montserrat Vallverdu
IEEE Journal of Biomedical and Health Informatics, 2019
Developing a tool which identifies emotions based on their effect on cardiac activity may have a ... more Developing a tool which identifies emotions based on their effect on cardiac activity may have a potential impact on clinical practice, since it may help in the diagnosing of psychoneural illnesses. In this study, a method based on the analysis of heart rate variability (HRV) guided by respiration is proposed. The method was based on redefining the high frequency (HF) band, not only to be centered at the respiratory frequency, but also to have a bandwidth dependent on the respiratory spectrum. The method was first tested using simulated HRV signals, yielding the minimum estimation errors as compared to classic and respiratory frequency centered at HF band based definitions, independently of the values of the sympathovagal ratio. Then, the proposed method was applied to discriminate emotions in a database of video-induced elicitation. Five emotional states, relax, joy, fear, sadness and anger, were considered. The maximum correlation between HRV and respiration spectra discriminated joy vs. relax, joy vs. each negative valence emotion, and fear vs. sadness with p-value ≤ 0.05 and AUC ≥ 0.70. Based on these results, human emotion characterization may be improved by adding respiratory information to HRV analysis.
2016 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2016
Monitoring the levels of sedation-analgesia may be helpful for managing patient stress on minimal... more Monitoring the levels of sedation-analgesia may be helpful for managing patient stress on minimally invasive medical procedures. Monitors based on EEG analysis and designed to assess general anesthesia cannot distinguish reliably between a light and deep sedation. In this work, the Poincaré plot is used as a nonlinear technique applied to EEG signals in order to characterize the levels of sedation-analgesia, according to observed categorical responses that were evaluated by means of Ramsay Sedation Scale (RSS). To study the effect of high frequencies due to EMG activity, three different frequency ranges (FR1=0.5-110 Hz, FR2=0.5-30 Hz and FR3=30-110 Hz) were considered. Indexes from power spectral analysis and plasma concentration of propofol and remifentanil were also compared with the bispectral index BIS. An adaptive Neurofuzzy Inference System was applied to model the interaction of the best indexes with respect to RSS score for each analysis, and leave-one-out cross validation method was used. The ability of the indexes to describe the level of sedation-analgesia, according with the RSS score, was evaluated using the prediction probability (Pk). The results showed that the ratio SD1/SD2FR3 contains useful information about the sedation level, and SD1FR2 and SD2FR2 had the best performance classifying response to noxious stimuli. Models including parameters from Poincaré plot emerge as a good estimator of sedation-analgesia levels.
2006 International Conference of the IEEE Engineering in Medicine and Biology Society, 2006
Autonomic Information Flow (AIF) reflects the time scale dependence of autonomic communications s... more Autonomic Information Flow (AIF) reflects the time scale dependence of autonomic communications such as vagal, sympathetic, and slower rhythms and their complex interplay. We investigated the hypothesis that pathologically disturbed short term control is associated with simplified complex long term control. This particular characteristic of altered autonomic communication was evaluated in different medical patient groups. Holter recordings were assessed in patients with multiple organ dysfunction (MODS) (26 survivors, 10 non-survivors); with heart failure (14 low risk-without history of aborted cardiac arrest (CA), 13 high risk--with history of CA); with idiopathic dilated cardiomyopathy (IDC) (26 low risk, 11 high risk of CA), after myocardial infarction (MI) (1221 low risk--survivors, 55 high risk--non-survivors); after abdominal aorta surgery (AAS, 32 length of stay in hospital LOS>7 days, 62 LOS < or =7 days). AIF of short and long time scales was investigated. We found a fundamental association of increased short term randomness and decreased long term randomness due to pathology. Concerning risk, high risk patients were characterized by increased short term complexity and decreased long term complexity in all patients groups with the exception of the IDC patients. We conclude that different time scales of AIF represent specific pathophysiological aspects of altered autonomic communication and control. The association of altered short term control with simplified long term behavior might be a pathophysiologically relevant compensation mechanism in the case of a disturbed fastest actuator. This knowledge might be useful for the development of comprehensive therapeutic strategies besides the predictive implications.
Medicina clínica, Jan 16, 2002
Our purpose was to assess the usefulness of a strategy based on the clinical presentation in orde... more Our purpose was to assess the usefulness of a strategy based on the clinical presentation in order to choose antibiotics in patients with non-severe community-acquired pneumonia (CAP). During one year, all patients admitted to the emergency department with a diagnosis of non-severe (Fine risk-classes I, II and III) CAP, were randomized and assigned into the following groups: GROUP 1: the clinical presentation was not taken into account and all patients were treated with levofloxacin; GROUP 2: patients with typical presentation were treated with amoxicillin and patients with atypical presentation were treated with clarithromycin. The following aspects were evaluated during the follow-up: presence of fever after 72 h of treatment, days of hospitalization and complications. The eventual population analyzed included 125 patients: 59 (47%) were assigned to Group 1 and 66 (53%) to Group 2. Patients assigned to Group 1 had a lower rate of fever after 72 h of treatment (7% vs 27%, p = 0.005...
Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2001
A dynamic analysis of the Correlation Integral (Cm) of the Heart Rate Variability signal (HRV) wa... more A dynamic analysis of the Correlation Integral (Cm) of the Heart Rate Variability signal (HRV) was applied to 50 patients with Hypertrophic Cardiomyopathy (HCM). A group of 55 healthy subjects was considered as a control group. The Correlation Integral is calculated within a moving time window in order to characterize the nonlinear dynamical behavior of the HRV of HCM patients
IEEE Engineering in Medicine and Biology Magazine, 2002
Abstract The HRV signals of 16 HCM patients are analyzed. Eight of them died or had a history of ... more Abstract The HRV signals of 16 HCM patients are analyzed. Eight of them died or had a history of aborted sudden cardiac death, forming the high-risk group. The other eight patients form the low-risk group. Stationarity analysis is applied in order to avoid ...
Chaos: An Interdisciplinary Journal of Nonlinear Science, 2007
The cardiovascular system incorporates several controlling mechanisms acting as feedback loops ov... more The cardiovascular system incorporates several controlling mechanisms acting as feedback loops over different time horizons. Because of their complex interrelationships, information-based methods such as autonomic information flow (AIF) functions promise to be useful in identifying normal and pathological behavior. Optimal adjustment between those controllers is necessary for healthy global behavior of the organism. We investigated the question as to whether there are typical relationships between short-term and long-term AIF by means of a meta-analysis of several of our own clinical studies of the mortality of patients with multiple organ dysfunction syndrome, heart failure, idiopathic dilated cardiomyopathy, and the length of stay in hospital after abdominal aorta surgery. We found a fundamental association of increased short-term randomness (decreased AIF) and decreased long-term randomness (increased AIF) due to pathology. A systems theoretic validation of this fundamental type of association was done by an appropriate mathematical model using a dissipative system with two feedback loops over different time horizons. The systematic simulation of an increasing collapse of the short feedback loop confirmed the inverse association between short-term and long-term information flow as a fundamental, system inherent type of readjustment that occurs under pathological conditions.
Biomedizinische Technik/Biomedical Engineering, 2006
The cardiovascular control system is mediated by mechanisms acting at different time scales, such... more The cardiovascular control system is mediated by mechanisms acting at different time scales, such as heart period, vagal, sympathetic, and other slower controllers. Since these elements are interrelated in a complex manner, classical control theory fails and information-based description, based on autonomic information flow (AIF) functions, is appropriate. We investigated the hypothesis that AIF functions of typical time scales specifically characterize autonomic dysfunction and prognosis. Holter recordings of patients with multiple organ dysfunction syndrome (MODS) (26 survivors, 10 non-survivors), heart failure (13 low risk, 13 high risk of cardiac arrest), idiopathic dilated cardiomyopathy (IDC) (26 low risk, 11 high risk), after abdominal aorta surgery (AAS) [32 with length of stay in hospital (LOS) >7 days; 62 with LOS < or =7 days] or with schizophrenia (n=20) were assessed and compared to 20 control subjects. We found different AIF time scales discriminating risk. AIF measures of heart beat period had predominant prognostic value in heart failure patients, those of vagal communication in MODS and IDC, and those of long-term communication after AAS. Schizophrenic patients were discriminated from controls by vagally mediated communication. Different time scales of AIF represent specific pathophysiological aspects of altered complex autonomic control (communication) and consequently have predictive implications.
Physiological Measurement, 2013
In this work, a univariate and multivariate statistical analysis of indexes derived from heart ra... more 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 endpoints 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
In this work, Refined Multiscale Entropy (RMSE) was applied to characterize risk of cardiac death... more In this work, Refined Multiscale Entropy (RMSE) was applied to characterize risk of cardiac death in ischemic cardiomyopathy patients, analyzing heart rate variability (HRV) by means of RR series during daytime and nighttime. RMSE approach measures an entropy rate in different time scales of a series, giving a multiscale characterization of complexity of that series. RMSE showed statistically significant differences (p<0.05) during daytime and nighttime only in middle time scales (τ=4–15 and τ=3–16, respectively). For these scales, RMSE was higher in low risk (SV) than in high risk (CM) group of cardiac death, indicating a reduction of the entropy-based complexity in CM when it was compared with SV. No statistical differences between risk groups were presented at time scale τ=1 (unfiltered original RR series). It can be concluded that the dynamics in middle time scales should be considered to better describe the HRV of patients with cardiac death.
Resumen: En este trabajo se presenta un nuevo algoritmo para el análisis automático de la dispers... more Resumen: En este trabajo se presenta un nuevo algoritmo para el análisis automático de la dispersión de QT (QTd) en registros de Holter de 3 derivaciones ortogonales (X, Y, Z). Su validación se ha realizado comparando en 1000 latidos cardíacos las medidas obtenidas por el algoritmo y las realizadas manualmente por dos expertos. Se comprueba que las medidas automáticas y manuales tienen unas diferencias despreciables ya que están dentro del mismo orden que las diferencias entre distintos expertos. Como aplicación, se ...
Journal of Clinical Monitoring and Computing, 2016
Purpose. The objective of this work is to compare the behavior of two electroencephalogram (EEG) ... more Purpose. The objective of this work is to compare the behavior of two electroencephalogram (EEG) based indices after drug induction and during recovery of consciousness. Methods. Data was recorded from 140 patients scheduled for general anaesthesia with a combination of propofol and remifentanil. The qCON 2000 monitor (Quantium Medical, Barcelona, Spain) was used to calculate the qCON and qNOX. The fall times and the rise times were defined at the start and at the end of the surgery. Loss of response to verbal command and loss of eyelash reflex were assessed during the transition from awake to anesthetized, defining the state of loss of consciousness (LOC). Movement as a response to laryngeal mask (LMA) insertion was interpreted as the response to the nociceptive stimuli. The patients were classified as movers or non-movers. The values of qCON and qNOX were statistically compared. Results. The qCON reached 65 in median (25th; 75th percentile) at 198.0 (114.0; 245.0) s after anaesthesia induction, while the qNOX fall time was significantly longer (p-value<0.05): 249.0 (189.0; 322.0) s. At the end of the surgery, the qNOX started to increase to 85 at 5.0 (-44.0; 46.0) s after recovery, while the qCON at 88.0 (-151.0; 40.0) s (p-value<0.05). The results show that the qCON has a predictive value of loss of consciousness such as loss of verbal command and eyelash reflex while the qNOX has a predictive value of response to noxious stimulation such as LMA insertion. Conclusion. The indices qCON and qNOX were able to detect differences between the times of actions of hypnotic and analgesic agents. The qCON showed faster decrease during induction while the qNOX showed a faster increase during recovery.
Proceedings of 18th Annual International Conference of the Ieee Engineering in Medicine and Biology Society, 1996
NPJ primary care respiratory medicine, Jun 2, 2016
Background: Chronic diseases are generating a major health and societal burden worldwide. Healthy... more Background: Chronic diseases are generating a major health and societal burden worldwide. Healthy lifestyles, including physical activity (PA), have proven efficacy in the prevention and treatment of many chronic conditions. But, so far, national PA surveillance systems, as well as strategies for promotion of PA, have shown low impact. We hypothesize that personalized modular PA services, aligned with healthcare, addressing the needs of a broad spectrum of individual profiles may show cost-effectiveness and sustainability. Methods: The current manuscript describes the protocol for regional implementation of collaborative selfmanagement services to promote PA in Catalonia (7.5 M habitants) during the period 2017-2019. The protocols of three implementation studies encompassing a broad spectrum of individual needs are reported. They have a quasiexperimental design. That is, a non-randomized intervention group is compared to a control group (usual care) using propensity score methods wherein age, gender and population-based health risk assessment are main matching variables. The principal innovations of the PA program are: i) Implementation of well-structured modular interventions promoting PA; ii) Information and communication technologies (ICT) to facilitate patient accessibility, support collaborative management of individual care plans and reduce costs; and iii) Assessment strategies based on the Triple Aim approach during and beyond the program deployment. Discussion: The manuscript reports a precise roadmap for large scale deployment of community-based ICT-supported integrated care services to promote healthy lifestyles with high potential for comparability and transferability to other sites. Trial registration: This study protocol has been registered at ClinicalTrials.org (NCT02976064). Registered November 24th, 2016.
Computing in Cardiology 2013, 2013
ABSTRACT Linear and non-linear measures applied to heart rate variability (HRV) can be used to qu... more ABSTRACT 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-CPAP (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
Tit, 2010
Regulatory sequence detection is a critical facet for understanding the cell mechanisms in order ... more Regulatory sequence detection is a critical facet for understanding the cell mechanisms in order to coordinate the response to stimuli. Protein synthesis involves the binding of a transcription factor to specific sequences in a process related to the gene expression initiation. A characteristic of this binding process is that the same factor binds with different sequences placed along all genome. Thus, any computational approach shows many difficulties related with this variability observed from the binding sequences. This paper proposes the detection of transcription factor binding sites based on a parametric uncertainty measurement (Rényi entropy). This detection algorithm evaluates the variation on the total Rényi entropy of a set of sequences when a candidate sequence is assumed to be a true binding site belonging to the set. The efficiency of the method is measured in form of receiver operating characteristic (ROC) curves on different transcription factors from Saccharomyces cerevisiae organism. The results are compared with other known motif detection algorithms such as Motif Discovery scan (MDscan) and multiple expectation-maximization (EM) for motif elicitation (MEME).
IEEE Journal of Biomedical and Health Informatics, 2019
Developing a tool which identifies emotions based on their effect on cardiac activity may have a ... more Developing a tool which identifies emotions based on their effect on cardiac activity may have a potential impact on clinical practice, since it may help in the diagnosing of psychoneural illnesses. In this study, a method based on the analysis of heart rate variability (HRV) guided by respiration is proposed. The method was based on redefining the high frequency (HF) band, not only to be centered at the respiratory frequency, but also to have a bandwidth dependent on the respiratory spectrum. The method was first tested using simulated HRV signals, yielding the minimum estimation errors as compared to classic and respiratory frequency centered at HF band based definitions, independently of the values of the sympathovagal ratio. Then, the proposed method was applied to discriminate emotions in a database of video-induced elicitation. Five emotional states, relax, joy, fear, sadness and anger, were considered. The maximum correlation between HRV and respiration spectra discriminated joy vs. relax, joy vs. each negative valence emotion, and fear vs. sadness with p-value ≤ 0.05 and AUC ≥ 0.70. Based on these results, human emotion characterization may be improved by adding respiratory information to HRV analysis.
2016 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2016
Monitoring the levels of sedation-analgesia may be helpful for managing patient stress on minimal... more Monitoring the levels of sedation-analgesia may be helpful for managing patient stress on minimally invasive medical procedures. Monitors based on EEG analysis and designed to assess general anesthesia cannot distinguish reliably between a light and deep sedation. In this work, the Poincaré plot is used as a nonlinear technique applied to EEG signals in order to characterize the levels of sedation-analgesia, according to observed categorical responses that were evaluated by means of Ramsay Sedation Scale (RSS). To study the effect of high frequencies due to EMG activity, three different frequency ranges (FR1=0.5-110 Hz, FR2=0.5-30 Hz and FR3=30-110 Hz) were considered. Indexes from power spectral analysis and plasma concentration of propofol and remifentanil were also compared with the bispectral index BIS. An adaptive Neurofuzzy Inference System was applied to model the interaction of the best indexes with respect to RSS score for each analysis, and leave-one-out cross validation method was used. The ability of the indexes to describe the level of sedation-analgesia, according with the RSS score, was evaluated using the prediction probability (Pk). The results showed that the ratio SD1/SD2FR3 contains useful information about the sedation level, and SD1FR2 and SD2FR2 had the best performance classifying response to noxious stimuli. Models including parameters from Poincaré plot emerge as a good estimator of sedation-analgesia levels.
2006 International Conference of the IEEE Engineering in Medicine and Biology Society, 2006
Autonomic Information Flow (AIF) reflects the time scale dependence of autonomic communications s... more Autonomic Information Flow (AIF) reflects the time scale dependence of autonomic communications such as vagal, sympathetic, and slower rhythms and their complex interplay. We investigated the hypothesis that pathologically disturbed short term control is associated with simplified complex long term control. This particular characteristic of altered autonomic communication was evaluated in different medical patient groups. Holter recordings were assessed in patients with multiple organ dysfunction (MODS) (26 survivors, 10 non-survivors); with heart failure (14 low risk-without history of aborted cardiac arrest (CA), 13 high risk--with history of CA); with idiopathic dilated cardiomyopathy (IDC) (26 low risk, 11 high risk of CA), after myocardial infarction (MI) (1221 low risk--survivors, 55 high risk--non-survivors); after abdominal aorta surgery (AAS, 32 length of stay in hospital LOS&amp;gt;7 days, 62 LOS &amp;lt; or =7 days). AIF of short and long time scales was investigated. We found a fundamental association of increased short term randomness and decreased long term randomness due to pathology. Concerning risk, high risk patients were characterized by increased short term complexity and decreased long term complexity in all patients groups with the exception of the IDC patients. We conclude that different time scales of AIF represent specific pathophysiological aspects of altered autonomic communication and control. The association of altered short term control with simplified long term behavior might be a pathophysiologically relevant compensation mechanism in the case of a disturbed fastest actuator. This knowledge might be useful for the development of comprehensive therapeutic strategies besides the predictive implications.
Medicina clínica, Jan 16, 2002
Our purpose was to assess the usefulness of a strategy based on the clinical presentation in orde... more Our purpose was to assess the usefulness of a strategy based on the clinical presentation in order to choose antibiotics in patients with non-severe community-acquired pneumonia (CAP). During one year, all patients admitted to the emergency department with a diagnosis of non-severe (Fine risk-classes I, II and III) CAP, were randomized and assigned into the following groups: GROUP 1: the clinical presentation was not taken into account and all patients were treated with levofloxacin; GROUP 2: patients with typical presentation were treated with amoxicillin and patients with atypical presentation were treated with clarithromycin. The following aspects were evaluated during the follow-up: presence of fever after 72 h of treatment, days of hospitalization and complications. The eventual population analyzed included 125 patients: 59 (47%) were assigned to Group 1 and 66 (53%) to Group 2. Patients assigned to Group 1 had a lower rate of fever after 72 h of treatment (7% vs 27%, p = 0.005...
Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2001
A dynamic analysis of the Correlation Integral (Cm) of the Heart Rate Variability signal (HRV) wa... more A dynamic analysis of the Correlation Integral (Cm) of the Heart Rate Variability signal (HRV) was applied to 50 patients with Hypertrophic Cardiomyopathy (HCM). A group of 55 healthy subjects was considered as a control group. The Correlation Integral is calculated within a moving time window in order to characterize the nonlinear dynamical behavior of the HRV of HCM patients
IEEE Engineering in Medicine and Biology Magazine, 2002
Abstract The HRV signals of 16 HCM patients are analyzed. Eight of them died or had a history of ... more Abstract The HRV signals of 16 HCM patients are analyzed. Eight of them died or had a history of aborted sudden cardiac death, forming the high-risk group. The other eight patients form the low-risk group. Stationarity analysis is applied in order to avoid ...
Chaos: An Interdisciplinary Journal of Nonlinear Science, 2007
The cardiovascular system incorporates several controlling mechanisms acting as feedback loops ov... more The cardiovascular system incorporates several controlling mechanisms acting as feedback loops over different time horizons. Because of their complex interrelationships, information-based methods such as autonomic information flow (AIF) functions promise to be useful in identifying normal and pathological behavior. Optimal adjustment between those controllers is necessary for healthy global behavior of the organism. We investigated the question as to whether there are typical relationships between short-term and long-term AIF by means of a meta-analysis of several of our own clinical studies of the mortality of patients with multiple organ dysfunction syndrome, heart failure, idiopathic dilated cardiomyopathy, and the length of stay in hospital after abdominal aorta surgery. We found a fundamental association of increased short-term randomness (decreased AIF) and decreased long-term randomness (increased AIF) due to pathology. A systems theoretic validation of this fundamental type of association was done by an appropriate mathematical model using a dissipative system with two feedback loops over different time horizons. The systematic simulation of an increasing collapse of the short feedback loop confirmed the inverse association between short-term and long-term information flow as a fundamental, system inherent type of readjustment that occurs under pathological conditions.
Biomedizinische Technik/Biomedical Engineering, 2006
The cardiovascular control system is mediated by mechanisms acting at different time scales, such... more The cardiovascular control system is mediated by mechanisms acting at different time scales, such as heart period, vagal, sympathetic, and other slower controllers. Since these elements are interrelated in a complex manner, classical control theory fails and information-based description, based on autonomic information flow (AIF) functions, is appropriate. We investigated the hypothesis that AIF functions of typical time scales specifically characterize autonomic dysfunction and prognosis. Holter recordings of patients with multiple organ dysfunction syndrome (MODS) (26 survivors, 10 non-survivors), heart failure (13 low risk, 13 high risk of cardiac arrest), idiopathic dilated cardiomyopathy (IDC) (26 low risk, 11 high risk), after abdominal aorta surgery (AAS) [32 with length of stay in hospital (LOS) &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;7 days; 62 with LOS &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; or =7 days] or with schizophrenia (n=20) were assessed and compared to 20 control subjects. We found different AIF time scales discriminating risk. AIF measures of heart beat period had predominant prognostic value in heart failure patients, those of vagal communication in MODS and IDC, and those of long-term communication after AAS. Schizophrenic patients were discriminated from controls by vagally mediated communication. Different time scales of AIF represent specific pathophysiological aspects of altered complex autonomic control (communication) and consequently have predictive implications.
Physiological Measurement, 2013
In this work, a univariate and multivariate statistical analysis of indexes derived from heart ra... more 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 endpoints 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
In this work, Refined Multiscale Entropy (RMSE) was applied to characterize risk of cardiac death... more In this work, Refined Multiscale Entropy (RMSE) was applied to characterize risk of cardiac death in ischemic cardiomyopathy patients, analyzing heart rate variability (HRV) by means of RR series during daytime and nighttime. RMSE approach measures an entropy rate in different time scales of a series, giving a multiscale characterization of complexity of that series. RMSE showed statistically significant differences (p<0.05) during daytime and nighttime only in middle time scales (τ=4–15 and τ=3–16, respectively). For these scales, RMSE was higher in low risk (SV) than in high risk (CM) group of cardiac death, indicating a reduction of the entropy-based complexity in CM when it was compared with SV. No statistical differences between risk groups were presented at time scale τ=1 (unfiltered original RR series). It can be concluded that the dynamics in middle time scales should be considered to better describe the HRV of patients with cardiac death.
Resumen: En este trabajo se presenta un nuevo algoritmo para el análisis automático de la dispers... more Resumen: En este trabajo se presenta un nuevo algoritmo para el análisis automático de la dispersión de QT (QTd) en registros de Holter de 3 derivaciones ortogonales (X, Y, Z). Su validación se ha realizado comparando en 1000 latidos cardíacos las medidas obtenidas por el algoritmo y las realizadas manualmente por dos expertos. Se comprueba que las medidas automáticas y manuales tienen unas diferencias despreciables ya que están dentro del mismo orden que las diferencias entre distintos expertos. Como aplicación, se ...
Journal of Clinical Monitoring and Computing, 2016
Purpose. The objective of this work is to compare the behavior of two electroencephalogram (EEG) ... more Purpose. The objective of this work is to compare the behavior of two electroencephalogram (EEG) based indices after drug induction and during recovery of consciousness. Methods. Data was recorded from 140 patients scheduled for general anaesthesia with a combination of propofol and remifentanil. The qCON 2000 monitor (Quantium Medical, Barcelona, Spain) was used to calculate the qCON and qNOX. The fall times and the rise times were defined at the start and at the end of the surgery. Loss of response to verbal command and loss of eyelash reflex were assessed during the transition from awake to anesthetized, defining the state of loss of consciousness (LOC). Movement as a response to laryngeal mask (LMA) insertion was interpreted as the response to the nociceptive stimuli. The patients were classified as movers or non-movers. The values of qCON and qNOX were statistically compared. Results. The qCON reached 65 in median (25th; 75th percentile) at 198.0 (114.0; 245.0) s after anaesthesia induction, while the qNOX fall time was significantly longer (p-value<0.05): 249.0 (189.0; 322.0) s. At the end of the surgery, the qNOX started to increase to 85 at 5.0 (-44.0; 46.0) s after recovery, while the qCON at 88.0 (-151.0; 40.0) s (p-value<0.05). The results show that the qCON has a predictive value of loss of consciousness such as loss of verbal command and eyelash reflex while the qNOX has a predictive value of response to noxious stimulation such as LMA insertion. Conclusion. The indices qCON and qNOX were able to detect differences between the times of actions of hypnotic and analgesic agents. The qCON showed faster decrease during induction while the qNOX showed a faster increase during recovery.
Proceedings of 18th Annual International Conference of the Ieee Engineering in Medicine and Biology Society, 1996
NPJ primary care respiratory medicine, Jun 2, 2016
Background: Chronic diseases are generating a major health and societal burden worldwide. Healthy... more Background: Chronic diseases are generating a major health and societal burden worldwide. Healthy lifestyles, including physical activity (PA), have proven efficacy in the prevention and treatment of many chronic conditions. But, so far, national PA surveillance systems, as well as strategies for promotion of PA, have shown low impact. We hypothesize that personalized modular PA services, aligned with healthcare, addressing the needs of a broad spectrum of individual profiles may show cost-effectiveness and sustainability. Methods: The current manuscript describes the protocol for regional implementation of collaborative selfmanagement services to promote PA in Catalonia (7.5 M habitants) during the period 2017-2019. The protocols of three implementation studies encompassing a broad spectrum of individual needs are reported. They have a quasiexperimental design. That is, a non-randomized intervention group is compared to a control group (usual care) using propensity score methods wherein age, gender and population-based health risk assessment are main matching variables. The principal innovations of the PA program are: i) Implementation of well-structured modular interventions promoting PA; ii) Information and communication technologies (ICT) to facilitate patient accessibility, support collaborative management of individual care plans and reduce costs; and iii) Assessment strategies based on the Triple Aim approach during and beyond the program deployment. Discussion: The manuscript reports a precise roadmap for large scale deployment of community-based ICT-supported integrated care services to promote healthy lifestyles with high potential for comparability and transferability to other sites. Trial registration: This study protocol has been registered at ClinicalTrials.org (NCT02976064). Registered November 24th, 2016.
Computing in Cardiology 2013, 2013
ABSTRACT Linear and non-linear measures applied to heart rate variability (HRV) can be used to qu... more ABSTRACT 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-CPAP (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
Tit, 2010
Regulatory sequence detection is a critical facet for understanding the cell mechanisms in order ... more Regulatory sequence detection is a critical facet for understanding the cell mechanisms in order to coordinate the response to stimuli. Protein synthesis involves the binding of a transcription factor to specific sequences in a process related to the gene expression initiation. A characteristic of this binding process is that the same factor binds with different sequences placed along all genome. Thus, any computational approach shows many difficulties related with this variability observed from the binding sequences. This paper proposes the detection of transcription factor binding sites based on a parametric uncertainty measurement (Rényi entropy). This detection algorithm evaluates the variation on the total Rényi entropy of a set of sequences when a candidate sequence is assumed to be a true binding site belonging to the set. The efficiency of the method is measured in form of receiver operating characteristic (ROC) curves on different transcription factors from Saccharomyces cerevisiae organism. The results are compared with other known motif detection algorithms such as Motif Discovery scan (MDscan) and multiple expectation-maximization (EM) for motif elicitation (MEME).