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  • Blood pressure variability analysis in supine and sitting position of healthy subjects

     Giraldo Giraldo, Beatriz F.; Calvo, Alejandro; Martínez, Beatriz; Arcentales, Andrés; Jane Campos, Raimon; Benito Vales, Salvador
    Date of publication: 2014
    Book chapter

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    Blood pressure carries a great deal of information about people¿s physical attributes. We analyzed the blood pressure signal in healthy subjects considering two positions, supine and sitting. 44 healthy subjects were studied. Parameters extracted from the blood pressure signal, related to time and frequency domain were used to compare the effect of postural position between supine and sitting. In time domain analysis, the time systolic interval and the time of blood pressure interval were higher in supine than in sitting position (p = 0.001 in both case). Parameters related to frequency peak, interquartile range, in frequency domain presented statistically significant difference (p¿< 0.0005 in both case). The blood pressure variability parameters presented smaller values in supine than in sitting position (p¿< 0.0005). In general, the position change of supine to sitting produces an increment in the pressure gradient inside heart, reflected in the blood pressure variability.

  • Evaluation of Laplacian diaphragm electromyographic recordings in a static inspiratory maneuver

     Estrada, Luis; Torres Cebrian, Abel; Garcia Casado, Javier; Ye-Lin, Y.; Jane Campos, Raimon
    Mediterranean Conference on Medical and Biological Engineering and Computing
    Presentation's date: 2014-09-27
    Presentation of work at congresses

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    Diaphragm electromyography (EMGdi) provides important information on diaphragm activity, to detect neuromuscular disorders of the most important muscle in the breathing inspiratory phase. EMGdi is habitually recorded using needles or esophageal catheters, with the implication of being invasive for patients. Surface electrodes offer an alternative for the non-invasive assessment of diaphragm activity. Ag/AgCl surface disc electrodes are used in monopolar or bipolar configuration to record EMGdi signals. On the other hand, Laplacian surface potential can be estimated by signal recording through active concentric ring electrodes. This kind of recording could reduce physiological interferences, increase the spatial selectivity and reduce orientation problems in the electrode location. The aim of this work is to compare EMGdi signals recorded simultaneously with disc electrodes in bipolar configuration and a Laplacian ring electrode over chest wall. EMGdi signal was recorded in one healthy subject during a breath hold maneuver and a static inspiratory maneuver based on Mueller¿s technique. In order to estimate the covered frequency range and the degree of noise contamination in both bipolar and Laplacian EMGdi signals, the cumulative percentage of the power spectrum and the signal to noise ratio in sub-bands were determined. Furthermore, diaphragm fatigue was evaluated by means of amplitude and frequency parameters. Our findings suggest that Laplacian EMGdi recording covers a broader frequency range although with higher noise contamination compared to bipolar EMGdi recording. Finally, in Laplacian recording fatigue indexes showed a clearer trend for muscle fatigue detection and also a reduced cardiac interference, providing an alternative to bipolar recording for diaphragm fatigue studies.

  • Feasibility of noninvasive single-channel automated differentiation of obstructive and central hypopneas with nasal airflow

     Morgenstern de Muller, Christian; Randerath, Winfried J.; Schwaibold, Matthias; Bolz, Armin; Jane Campos, Raimon
    Respiration
    Date of publication: 2013-03
    Journal article

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    Background: The identification of obstructive and central hypopneas is considered challenging in clinical practice. Presently, obstructive and central hypopneas are usually not differentiated or scores lack reliability due to the technical limitations of standard polysomnography. Esophageal pressure measurement is the gold-standard for identifying these events but its invasiveness deters its usage in daily practice. Objectives: To determine the feasibility and efficacy of an automatic noninvasive analysis method for the differentiation of obstructive and central hypopneas based solely on a single-channel nasal airflow signal. The obtained results are compared with gold-standard esophageal pressure scores. Methods: A total of 41 patients underwent full night polysomnography with systematic esophageal pressure recording. Two experts in sleep medicine independently differentiated hypopneas with the gold-standard esophageal pressure signal. Features were automatically extracted from the nasal airflow signal of each annotated hypopnea to train and test the automatic analysis method. Interscorer agreement between automatic and visual scorers was measured with Cohen's kappa statistic (¿). Results: A total of 1,237 hypopneas were visually differentiated. The automatic analysis achieved an interscorer agreement of ¿ = 0.37 and an accuracy of 69% for scorer A, ¿ = 0.40 and 70% for scorer B and ¿ = 0.41 and 71% for the agreed scores of scorers A and B. Conclusions: The promising results obtained in this pilot study demonstrate the feasibility of noninvasive single-channel hypopnea differentiation. Further development of this method may help improving initial diagnosis with home screening devices and offering a means of therapy selection and/or control.

    Background: The identification of obstructive and central hypopneas is considered challenging in clinical practice. Presently, obstructive and central hypopneas are usually not differentiated or scores lack reliability due to the technical limitations of standard polysomnography. Esophageal pressure measurement is the gold-standard for identifying these events but its invasiveness deters its usage in daily practice. Objectives: To determine the feasibility and efficacy of an automatic noninvasive analysis method for the differentiation of obstructive and central hypopneas based solely on a single-channel nasal airflow signal. The obtained results are compared with gold-standard esophageal pressure scores. Methods: A total of 41 patients underwent full night polysomnography with systematic esophageal pressure recording. Two experts in sleep medicine independently differentiated hypopneas with the gold-standard esophageal pressure signal. Features were automatically extracted from the nasal airflow signal of each annotated hypopnea to train and test the automatic analysis method. Interscorer agreement between automatic and visual scorers was measured with Cohen’s kappa statistic (κ). Results: A total of 1,237 hypopneas were visually differentiated. The automatic analysis achieved an interscorer agreement of κ = 0.37 and an accuracy of 69% for scorer A, κ = 0.40 and 70% for scorer B and κ = 0.41 and 71% for the agreed scores of scorers A and B. Conclusions: The promising results obtained in this pilot study demonstrate the feasibility of noninvasive single-channel hypopnea differentiation. Further development of this method may help improving initial diagnosis with home screening devices and offering a means of therapy selection and/or control.

  • Cardiac interference reduction in diaphragmatic MMG signals during a maintained inspiratory pressure test

     Sarlabous, Leonardo; Torres Cebrian, Abel; Fiz, José Antonio; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2013-07
    Presentation of work at congresses

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    A recursive least square (RLS) adaptive filtering algorithm for reduction of cardiac interference in diaphragmatic mecanomyographic (MMGdi) signals is addressed in this paper. MMGdi signals were acquired with a capacitive accelerometer placed between 7th and 8th intercostal spaces, on the right anterior axillary line, during a maintained inspiratory pressure test. Subjects were asked to maintain a constant inspiratory pressure with a mouthpiece connected to a closed tube (without breathing). This maneuver was repeated at five different contraction efforts: apnea (no effort), 20 cmH2O, 40 cmH2O, 60 cmH2O and maximum voluntary contraction. An adaptive noise canceller (ANC) using the RLS algorithm was applied on the MMGdi signals. To evaluate the behavior of the ANC, the MMGdi signals were analyzed in two segments: with and without cardiac interference (WCI and NCI, respectively). In both segments it was analyzed the power spectral density (PSD), and the ARV and RMS amplitude parameters for each contraction effort. With the proposed ANC algorithm the amplitude parameters of the WCI segments were reduced to a level similar to the one of the NCI segments. The obtained results showed that ANC using the RLS algorithm allows to significantly reduce the cardiac interference in MMGdi signals.

  • Cancellation of cardiac interference in diaphragm EMG signals using an estimate of ECG reference signal

     Torres Cebrian, Abel; Fiz, José Antonio; Jane Campos, Raimon
    Mediterranean Conference on Medical and Biological Engineering and Computing
    Presentation's date: 2013-09-27
    Presentation of work at congresses

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    The analysis of the electromyographic signal of the diaphragm muscle (EMGdi) can provide important information in order to evaluate the respiratory muscular function. However, EMGdi signals are usually contaminated by the electrocardiographic (ECG) signal. An adaptive noise cancellation (ANC) based on event-synchronous cancellation can be used to reduce the ECG interference in the recorded EMGdi activity. In this paper, it is proposed an ANC scheme for cancelling the ECG interference in EMGdi signals using only the EMGdi signal (without acquiring the ECG signal). In this case the detection of the QRS complex has been performed directly in the EMGdi signal, and the ANC algorithm must be robust to false or missing QRS detections. Furthermore, an automatic criterion to select the adaptive constant of the LMS algorithm has been proposed (µ). The µ constant is selected automatically so that the canceling signal energy equals the energy of the reference signal (which is an estimation of the ECG interference present in the EMGdi signal). This approach optimizes the tradeoff between cancellation of ECG interference and attenuation of EMG component. A number of weights equivalent of a time window that contains several QRS complexes is selected in order to make the algorithm robust to QRS detection errors.

  • Evaluating spatial characteristics of upper-limb movements from EMG signals

     Urra, Oiane; Casals Gelpi, Alicia; Jane Campos, Raimon
    Mediterranean Conference on Medical and Biological Engineering and Computing
    Presentation's date: 2013-09-27
    Presentation of work at congresses

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    Stroke is a major cause of disability, usually causing hemiplegic damage on the motor abilities of the patient. Stroke rehabilitation seeks restoring normal motion on the affected limb. However, `normality¿ of movements is usually assessed by clinical and functional tests, without considering how the motor system responds to therapy. We hypothesized that electromyographic (EMG) recordings could provide useful information for evaluating the outcome of rehabilitation from a neuromuscular perspective. Four healthy subjects were asked to perform 14 different functional movements simulating the action of reaching over a table. Each movement was defined according to the starting and target positions that the subject had to connect using linear trajectories. Bipolar recordings of EMG signals were taken from biceps and triceps muscles, and spectral and temporal characteristics were extracted for each movement. Using pattern recognition techniques we found that only two EMG channels were sufficient to accurately determine the spatial characteristics of motor activity: movement direction, length and execution zone. Our results suggest that muscles may fire in a patterned way depending on the specific characteristics of the movement and that EMG signals may codify such detailed information. These findings may be of great value to quantitatively assess poststroke rehabilitation and to compare the neuromuscular activity of the affected and unaffected limbs, from a physiological perspective. Furthermore, disturbed movements could be characterized in terms of the muscle function to identify, which is the spatial characteristic that fails, e.g. movement direction, and guide personalized rehabilitation to enhance the training of such characteristic.

  • Characterization of laplacian surface electromyographic signals during isometric contraction in biceps brachii

     Estrada, Luis; Torres Cebrian, Abel; Garcia Casado, Javier; Prats Boluda, Gema; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2013-07
    Presentation of work at congresses

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    Surface electromyography (sEMG) is a noninvasive technique for monitoring the electrical activity produced by the muscles. Usually, sEMG is performed by carrying out monopolar or bipolar recordings by means of conventional Ag/AgCl electrodes. In contrast, Laplacian recordings of sEMG could also be obtained by using coaxial ring electrodes. Laplacian recordings increase spatial resolution and attenuate other distant bioelectric interferences. Nevertheless, the spectral characteristics of this kind of recordings have been scarcely studied. The objective of this paper is to characterize the sEMG signals recorded with a Laplacian ring electrode and to compare them with traditional bipolar recordings with disc electrodes. Both kinds of signals were collected simultaneously in two healthy subjects during resting and sustained isometric voluntary contraction activities in biceps brachii. The conducted study computed the cumulative percentage of the power spectrum of sEMG so as to determine the energy bandwidth of the two kinds of recordings and the signal to noise ratio in different bands of the sEMG spectrum. Also, muscle fatigue, a condition when muscle force is reduced, was assessed using indexes from amplitude and frequency domain. The results of this study suggest that Laplacian sEMG has higher spectral bandwidth but a lower signal to noise ratio in comparison to bipolar sEMG. In addition, frequency fatigue indexes showed that Laplacian recording had better response than bipolar recording, which suggests that Laplacian electrode can be useful to study muscular fatigue due to better spatial resolution.

  • Estimation of instantaneous frequency from empirical mode decomposition on respiratory sounds analysis

     Lozano, Manuel; Fiz, José Antonio; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2013-06
    Presentation of work at congresses

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    Instantaneous frequency (IF) calculated by empirical mode decomposition (EMD) provides a novel approach to analyze respiratory sounds (RS). Traditionally, RS have been analyzed using classical time-frequency distributions, such as short-time Fourier transform (STFT) or wavelet transform (WT). However, EMD has become a powerful tool for nonlinear and non-stationary data analysis. IF estimated by EMD has two major advantages: its high temporal resolution and the fact that a priori knowledge of the signal characteristics is not required. In this study, we have estimated IF by EMD on real RS signals in order to identify continuous adventitious sounds (CAS), such as wheezes, within inspiratory sounds cycles. We show that there are differences in IF distribution among frequency scales of RS signal when CAS are within RS. Therefore, a new method for RS analysis and classification may be developed by combining both EMD and IF.

  • Obstructive sleep apnea in a rat model: effects of anesthesia on autonomic evaluation from heart rate variability measures

     Jane Campos, Raimon; Lázaro, Jesús; Ruiz, Puy; Gil, Eduardo; Navajas, Daniel; Farré, Ramon; Laguna, Pablo
    Computing in Cardiology
    Presentation's date: 2013-09-25
    Presentation of work at congresses

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    Rat model of Obstructive Sleep Apnea (OSA) is a realistic approach for studying physiological mechanisms involved in sleep. Rats are usually anesthetized and autonomic nervous system (ANS) could be blocked. This study aimed to assess the effect of anesthesia on ANS activity during OSA episodes. Seven male SpragueDawley rats were anesthetized intraperitoneally with urethane (1 g/kg). The experiments were conducted applying airway obstructions, simulating 15s-apnea episodes for 15 minutes. Five signals were acquired: respiratory pressure and flow, Sa02, ECG and photoplethysmography (PPG). In total, 210 apnea episodes were studied. Normalized power spectrum of Pulse Rate Variability (PRV) was analyzed in the Low Frequency (LF) and High Frequency (HF) bands, for each episode in consecutive 15s intervals (before, during and after the apnea). All episodes showed changes in respiratory flow and Sa02 signal. Conversely, decreases in the amplitude fluctuations of PPG (DAP) were not observed. Normalized LF presented extremely low values during breathing (median=7,67%), suggesting inhibition of sympathetic system due to anesthetic effect. Subtle increases of LF were observed during apnea. HRV and PPG analysis during apnea could be an indirect tool to assess the effect and deep of anesthesia.

  • Index for estimation of muscle force from mechanomyogrpahy based on the Lempel-Ziv algorithm

     Sarlabous, Leonardo; Torres Cebrian, Abel; Fiz, José Antonio; Morera, Josep; Jane Campos, Raimon
    Journal of electromyography and kinesiology
    Date of publication: 2013-02-19
    Journal article

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    The study of the amplitude of respiratory muscle mechanomyographic (MMG) signals could be useful in clinical practice as an alternative non-invasive technique to assess respiratory muscle strength. The MMG signal is stochastic in nature, and its amplitude is usually estimated by means of the average rectified value (ARV) or the root mean square (RMS) of the signal. Both parameters can be used to estimate MMG activity, as they correlate well with muscle force. These estimations are, however, greatly affected by the presence of structured impulsive noise that overlaps in frequency with the MMG signal. In this paper, we present a method for assessing muscle activity based on the Lempel-Ziv algorithm: the Multistate Lempel-Ziv (MLZ) index. The behaviour of the MLZ index was tested with synthesized signals, with various amplitude distributions and degrees of complexity, and with recorded diaphragm MMG signals. We found that this index, like the ARV and RMS parameters, is positively correlated with changes in amplitude of the diaphragm MMG components, but is less affected by components that have non-random behaviour (like structured impulsive noise). Therefore, the MLZ index could provide more information to assess the MMG-force relationship.

  • Electrical stimulation of the dorsal genital nerve to treat neurogenic detrusor overactivity

     Opisso Salleras, Eloy
    Defense's date: 2013-10-23
    Universitat Politècnica de Catalunya
    Theses

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  • Estudio de las Fuerzas de Interacción para la Minimización de Esfuerzos en Rehabilitación Robotizada

     Amigo Vásquez, Luis Ernesto
    Defense's date: 2013-10-17
    Universitat Politècnica de Catalunya
    Theses

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  • Snoring and Arousals in full-night polysomnographic studies from Sleep Apnea-Hypopnea Syndrome patients  Open access

     Gil De Mesquita, Joana Margarida
    Defense's date: 2013-02-22
    Department of Automatic Control, Universitat Politècnica de Catalunya
    Theses

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    SAHS (Sleep Apnea-Hypopnea Syndrome) is recognized to be a serious disorder with high prevalence in the population. The main clinical triad for SAHS is made up of 3 symptoms: apneas and hypopneas, chronic snoring and excessive daytime sleepiness (EDS). The gold standard for diagnosing SAHS is an overnight polysomnographic study performed at the hospital, a laborious, expensive and time-consuming procedure in which multiple biosignals are recorded. In this thesis we offer improvements to the current approaches to diagnosis and assessment of patients with SAHS. We demonstrate that snoring and arousals, while recognized key markers of SAHS, should be fully appreciated as essential tools for SAHS diagnosis. With respect to snoring analysis (applied to a 34 subjects¿ database with a total of 74439 snores), as an alternative to acoustic analysis, we have used less complex approaches mostly based on time domain parameters. We concluded that key information on SAHS severity can be extracted from the analysis of the time interval between successive snores. For that, we built a new methodology which consists on applying an adaptive threshold to the whole night sequence of time intervals between successive snores. This threshold enables to identify regular and non-regular snores. Finally, we were able to correlate the variability of time interval between successive snores in short 15 minute segments and throughout the whole night with the subject¿s SAHS severity. Severe SAHS subjects show a shorter time interval between regular snores (p=0.0036, AHI cp(cut-point): 30h-1) and less dispersion on the time interval features during all sleep. Conversely, lower intra-segment variability (p=0.006, AHI cp: 30h-1) is seen for less severe SAHS subjects. Also, we have shown successful in classifying the subjects according to their SAHS severity using the features derived from the time interval between regular snores. Classification accuracy values of 88.2% (with 90% sensitivity, 75% specificity) and 94.1% (with 94.4% sensitivity, 93.8% specificity) for AHI cut-points of severity of 5 and 30h-1, respectively. In what concerns the arousal study, our work is focused on respiratory and spontaneous arousals (45 subjects with a total of 2018 respiratory and 2001 spontaneous arousals). Current beliefs suggest that the former are the main cause for sleep fragmentation. Accordingly, sleep clinicians assign an important role to respiratory arousals when providing a final diagnosis on SAHS. Provided that the two types of arousals are triggered by different mechanisms we hypothesized that there might exist differences between their EEG content. After characterizing our arousal database through spectral analysis, results showed that the content of respiratory arousals on a mild SAHS subject is similar to that of a severe one (p>>0.05). Similar results were obtained for spontaneous arousals. Our findings also revealed that no differences are observed between the features of these two kinds of arousals on a same subject (r=0.8, p<0.01 and concordance with Bland-Altman analysis). As a result, we verified that each subject has almost like a fingerprint or signature for his arousals¿ content and is similar for both types of arousals. In addition, this signature has no correlation with SAHS severity and this is confirmed for the three EEG tracings (C3A2, C4A1 and O1A2). Although the trigger mechanisms of the two arousals are known to be different, our results showed that the brain response is fairly the same for both of them. The impact that respiratory arousals have in the sleep of SAHS patients is unquestionable but our findings suggest that the impact of spontaneous arousals should not be underestimated.

  • Multiclass classification of subjects with sleep apnoea-hypopnoea syndrome through snoring analysis

     Sola Soler, Jordi; Fiz, José Antonio; Morera, Josep; Jane Campos, Raimon
    Medical engineering and physics
    Date of publication: 2012-11
    Journal article

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    Reducción de interferencia cardíaca en señales MMG diafragmáticas de un protocolo de carga incremental sostenida mediante filtrado adaptativo RLS  Open access

     Sarlabous Uranga, Leonardo; Torres Cebrian, Abel; Fiz Fernández, José A.; Jane Campos, Raimon
    Congreso Anual de la Sociedad Española de Ingeniería Biomédica
    Presentation's date: 2012-11-20
    Presentation of work at congresses

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    En este trabajo se aplicó el filtrado adaptativo empleando el algoritmo RLS para reducir la interferencia de origen cardíaco en las señales mecanomiográficas diafragmáticas (MMGdi) registradas durante un protocolo de carga incremental sostenida. La señal MMGdi fue dividida en tramos con y sin ruido cardíaco, CRC y SRC, respectivamente. En cada tramo se estudio el comportamiento de la densidad espectral de potencia (DEP), y los parámetros de amplitud RMS y ARV para cada una de las cargas inspiratorias que conforman el test. Los resultados obtenidos, empleando filtro adaptativo de orden =50, con el algoritmo RLS y valores de - = 1, permiten reducir considerablemente la interferencia cardíaca en las señales MMGdi.

  • Respiratory and spontaneous arousals in patients with sleep apnea hypopnea syndrome

     Gil De Mesquita, Joana Margarida; Poree, F.; Carrault, Guy; Fiz, José Antonio; Abad, Jorge; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2012-08
    Presentation of work at congresses

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    Sleep in patients with Sleep Apnea-Hypopnea Syndrome (SAHS) is frequently interrupted with arousals. Increased amounts of arousals result in shortening total sleep time and repeated sleep-arousal change can result in sleep fragmentation. According to the American Sleep Disorders Association (ASDA) an arousal is a marker of sleep disruption representing a detrimental and harmful feature for sleep. The nature of arousals and its role on the regulation of the sleep process raises controversy and has sparked the debate in the last years. In this work, we analyzed and compared the EEG spectral content of respiratory and spontaneous arousals on a database of 45 SAHS subjects. A total of 3980 arousals (1996 respiratory and 1984 spontaneous) were analyzed. The results showed no differences between the spectral content of the two kinds of arousals. Our findings raise doubt as to whether these two kinds of arousals are truly triggered by different organic mechanisms.

    Sleep in patients with Sleep Apnea-Hypopnea Syndrome (SAHS) is frequently interrupted with arousals. Increased amounts of arousals result in shortening total sleep time and repeated sleep-arousal change can result in sleep fragmentation. According to the American Sleep Disorders Association (ASDA) an arousal is a marker of sleep disruption representing a detrimental and harmful feature for sleep. The nature of arousals and its role on the regulation of the sleep process raises controversy and has sparked the debate in the last years. In this work, we analyzed and compared the EEG spectral content of respiratory and spontaneous arousals on a database of 45 SAHS subjects. A total of 3980 arousals (1996 respiratory and 1984 spontaneous) were analyzed. The results showed no differences between the spectral content of the two kinds of arousals. Our findings raise doubt as to whether these two kinds of arousals are truly triggered by different organic mechanisms. Furthermore, they may also challenge the current beliefs regarding the underestimation of the importance of spontaneous arousals and their contribution to sleep fragmentation in patients suffering from SAHS.

  • Evaluation and adaptive attenuation of the cardiac vibration interference in mechanomyographic signals

     Sarlabous Uranga, Leonardo; Torres Cebrian, Abel; Fiz, José Antonio; Morera Prat, Josep Maria; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2012-09-01
    Presentation of work at congresses

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    The study of the mechanomyographic signal of the diaphragm muscle (MMGdi) is a promising technique in order to evaluate the respiratory muscles effort. The relationship between amplitude and frequency parameters of this signal with the respiratory effort performed during respiration is of great interest for researchers and physicians due to its diagnostic potentials. However, MMGdi signals are frequently contaminated by a cardiac vibration or mechanocardiographic (MCG) signal. An adaptive noise cancellation (ANC) can be used to reduce the MCG interference in the recorded MMGdi activity. In this paper, it is evaluated the proposed ANC scheme by means of a synthetic MMGdi signal with a controlled MCG interference. The Pearson’s correlation coefficient (PCC) between both root mean square (RMS) and mean frequency (fm) of the synthetic MMGdi signal are considerably reduced with the presence of cardiac vibration noise (from 0.95 to 0.87, and from 0.97 to 0.76, respectively). With the ANC algorithm proposed the effect of the MCG noise on the amplitude and frequency of MMG parameters is reduced considerably (PCC of 0.93 and 0.97 for the RMS and fm, respectively). The ANC method proposed in this work is an interesting technique to attenuate the cardiac interference in respiratory MMG signals. Further investigation should be carried out to evaluate the performance of the ANC algorithm in real MMGdi signals.

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    Evaluación de diferentes algoritmos adaptativos para la atenuación de la interferencia cardiaca en señales mecanomiográficas simuladas  Open access

     Torres Cebrian, Abel; Sarlabous Uranga, Leonardo; Fiz Fernández, José A.; Jane Campos, Raimon
    Congreso Anual de la Sociedad Española de Ingeniería Biomédica
    Presentation's date: 2012-11-21
    Presentation of work at congresses

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    El estudio de la señal mecanomiográfica del músculo diafragma (MMGdi) es una técnica utilizada para evaluar el esfuerzo muscular respiratorio. El estudio de la relación entre los parámetros de amplitud y frecuencia de esta señal con el esfuerzo respiratorio realizado es de gran interés para investigadores y médicos debido a su potencial de diagnóstico sobre la función muscular respiratoria. Las señales MMGdi se ven afectas por una componente interferente correspondiente a la actividad vibratoria cardíaca o interferencia mecanocardiográfica (MCG). Para reducir o atenuar esta actividad se puede utilizar una cancelación adaptativa de interferencias (CAI). En este trabajo se ha evaluado el esquema de CAI propuesto mediante una señal MMGdi sintética generada con amplitud y frecuencia controlada a la que se le ha añadido ruido MCG real adquirido durante apnea. El coeficiente de correlación de Pearson (r) entre la amplitud y la frecuencia teóricas, y la amplitud y la frecuencia evaluadas mediante el RMS y la frecuencia media del espectro, respectivamente, disminuye considerablemente cuando se añade el ruido cardíaco a la señal MMGdi sintética: pasa de 0.95 a 0.87 para la amplitud, y de 0.97 a 0.76 para la frecuencia. Con los algoritmos de CAI propuestos el efecto del ruido MCG sobre la actividad MMGdi se reduce considerablemente (r de 0.93 para la amplitud y 0.97 para la frecuencia media). El método de CAI propuesto en este trabajo es una técnica adecuada para atenuar la interferencia MCG en señales MMGdi.

  • Estudio de la respiración periódica en el ascenso a altitudes extremas a partir de la señal de volumen respiratorio

     Garde Martinez, Ainara; Giraldo Giraldo, Beatriz F.; Jane Campos, Raimon; Latshang, T.D.; Turk, A. J.; Hess, T; Bosch, M. M.; Barthelmes, D.; Hefti, J. P.; Maggiorini, M.; Hefti, U; Merz, T. M.; Schoch, O. D.; Bloch, K. E.
    Congreso Anual de la Sociedad Española de Ingeniería Biomédica
    Presentation of work at congresses

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  • Ensemble-based time alignment of biomedical signals

     Garde Martinez, Ainara; Laguna Lasaosa, Pablo; Giraldo Giraldo, Beatriz F.; Jane Campos, Raimon; Sörnmo, Leif
    International Workshop on Biosignal Interpretation
    Presentation's date: 2012-07
    Presentation of work at congresses

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  • Periodic breathing during ascent to extreme altitude quantified by spectral analysis of the respiratory volume signal

     Garde Martinez, Ainara; Giraldo Giraldo, Beatriz F.; Jane Campos, Raimon; Latshang, T.D.; Turk, A. J.; Hess, T.; Bosch, M. M.; Barthelmes, D.; Pichler, J.; Maggiorini, M.; Hefti, U; Merz, T. M.; Schoch, O. D.; Bloch, K. E.
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2012-09
    Presentation of work at congresses

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  • Analysis of the respiratory flow cycle morphology in chronic heart failure patients applying principal components analysis

     Garde Martinez, Ainara; Giraldo Giraldo, Beatriz F.; Sörnmo, Leif; Jane Campos, Raimon
    Annual International Conference of the IEEE Engineering in Medicine and Biology Society
    Date of publication: 2012
    Journal article

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  • All night analysis of time interval between snores in subjects with sleep apnea hypopnea syndrome

     Gil De Mesquita, Joana Margarida; Sola Soler, Jordi; Fiz, José Antonio; Morera, Josep; Jane Campos, Raimon
    Medical and biological engineering and computing
    Date of publication: 2012-04
    Journal article

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  • Premio CASEIB2012 a las contribuciones científicas de los estudiantes

     Urra, Oiane; Fiz, José Antonio; Abad, Jorge; Jane Campos, Raimon
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  • Normal non-regular snores as a tool for screening SAHS severity

     Gil De Mesquita, Joana Margarida; Fiz, José Antonio; Sola Soler, Jordi; Morera Prat, Josep Maria; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2011-09-01
    Presentation of work at congresses

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    Snoring is one of the earliest and most consistent sign of upper airway obstruction leading to Sleep Apnea-Hypopnea Syndrome (SAHS). Several studies on post-apneic snores, snores that are emitted immediately after an apnea, have already proven that this type of snoring is most distinct from that of normal snoring. However, post-apneic snores are more unlikely and sometimes even inexistent in simple snorers and mild SAHS subjects. In this work we address that issue by proposing the study of normal non-regular snores. They correspond to successive snores that are separated by normal breathing cycles. The results obtained establish the feasibility of acoustic parameters of normal non-regular snores as a promising tool for a prompt screening of SAHS severity.

  • Estudio de la morfología del ciclo respiratorio mediante el análisis de componentes principales en pacientes con insuficiencia cardíaca crónica

     Garde Martinez, Ainara; Sörnmo, Leif; Jane Campos, Raimon; Giraldo Giraldo, Beatriz F.
    Congreso Anual de la Sociedad Española de Bioingeniería
    Presentation of work at congresses

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  • Analysis of the respiratory flow cycle morphology in chronic heart failure patients applying principal components analysis

     Garde Martinez, Ainara; Giraldo Giraldo, Beatriz F.; Sörnmo, Leif; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2011-09
    Presentation of work at congresses

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  • Clasificación bayesiana de sujetos roncadores con Síndrome de Apnea Hipoapnea del Sueño mediante un método Kernel

     Sola Soler, Jordi; Fiz, José Antonio; Morera, José; Jane Campos, Raimon
    Congreso Anual de la Sociedad Española de Ingeniería Biomédica
    Presentation's date: 2011-11-17
    Presentation of work at congresses

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  • Comparación de mediciones de resistencia de la vía respiratoria superior mediante la relación de presión esofágica/flujo respiratorio durante el sueño

     Schwaibold, Matthias; Morgenstern de Muller, Christian; Bolz, Armin; Jane Campos, Raimon; Randerath, Winfried J.
    Congreso Anual de la Sociedad Española de Bioingeniería
    Presentation's date: 2011-11
    Presentation of work at congresses

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  • Ronquidos no-regulares como herramienta de screening de severidad de SAHS

     Gil De Mesquita, Joana Margarida; Fiz, José Antonio; Sola Soler, Jordi; Morera, Josep; Jane Campos, Raimon
    Congreso Anual de la Sociedad Española de Bioingeniería
    Presentation's date: 2011-11
    Presentation of work at congresses

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  • Snoring analysis for the screening of sleep apnea hypopnea syndrome with a single-channel device developed using polysomnographic and snoring databases

     Jane Campos, Raimon; Fiz, José A.; Sola Soler, Jordi; Gil De Mesquita, Joana Margarida; Morera Prat, Josep Maria
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2011-09-03
    Presentation of work at congresses

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    Several studies have shown differences in acoustic snoring characteristics between patients with Sleep Apnea-Hypopnea Syndrome (SAHS) and simple snorers. Usually a few manually isolated snores are analyzed, with an emphasis on postapneic snores in SAHS patients. Automatic analysis of snores can provide objective information over a longer period of sleep. Although some snore detection methods have recently been proposed, they have not yet been applied to full-night analysis devices for screening purposes. We used a new automatic snoring detection and analysis system to monitor snoring during full-night studies to assess whether the acoustic characteristics of snores differ in relation to the Apnea-Hypopnea Index (AHI) and to classify snoring subjects according to their AHI. A complete procedure for device development was designed, using databases with polysomnography (PSG) and snoring signals. This included annotation of many types of episodes by an expert physician: snores, inspiration and exhalation breath sounds, speech and noise artifacts, The AHI of each subject was estimated with classical PSG analysis, as a gold standard. The system was able to correctly classify 77% of subjects in 4 severity levels, based on snoring analysis and sound-based apnea detection. The sensitivity and specificity of the system, to identify healthy subjects from pathologic patients (mild to severe SAHS), were 83% and 100%, respectively. Besides, the Apnea Index (AI) obtained with the system correlated with the obtained by PSG or Respiratory Polygraphy (RP) (r=0.87, p<0.05).

  • Sleep dynamics analysis as a source of reliable sleep quality assessment

     Urra Vicario, Oiane; Jane Campos, Raimon
    Congreso Anual de la Sociedad Española de Bioingeniería
    Presentation's date: 2011-11
    Presentation of work at congresses

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  • Evaluation of the respiratory muscles efficiency during an incremental flow respiratory test

     Sarlabous Uranga, Leonardo; Torres Cebrian, Abel; Fiz, José A.; Gea, J; Martínez-Llorens, Juana M.; Morera Prat, Josep Maria; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2011-09-01
    Presentation of work at congresses

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    The aim of this study was to evaluate the respiratory muscles efficiency during a progressive incremental flow (IF) respiratory test in healthy and Chronic Obstructive Pulmonary Disease (COPD) subjects. To achieve this, the relationship between mouth Inspiratory Pressure (IP) increment, which is a measure of the force produced by respiratory muscles, and respiratory muscular activity increment, evaluated by means of Mechanomyografic (MMG) signals of the diaphragm muscle, was analyzed. Moreover, the correlation between the respiratory efficiency measure and the obstruction severity of the subjects was also examined. Data from two groups of subjects were analyzed. One group consisted of four female subjects (two healthy subjects and two moderate COPD patients) and the other consisted of ten male subjects (six severe and four very severe COPD patients). All subjects performed an easy IF respiratory test, in which small IP values were reached. We have found that there is an increase of amplitude and a displacement towards low frequencies in the MMG signals when the IP increases. Furthermore, it has also been found that respiratory muscles efficiency is lower when greater the obstructive severity of the patients is, and it is lower in women than in men. These results suggest that the information provided by MMG signals could be used to evaluate the muscular efficiency in healthy and COPD subjects

  • Comparison of upper airway respiratory resistance measurements with the esophageal pressure/airflow relationship during sleep

     Morgenstern de Muller, Christian; Schwaibold, Matthias; Bolz, Armin; Randerath, Winfried J.; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2011-09-01
    Presentation of work at congresses

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    Measurement of upper airway resistance is of interest in sleep disordered breathing to estimate upper airway patency. Resistance is calculated with the airflow and respiratory effort signals. However, there is no consensus on a standard for upper airway resistance measurement. This study proposes a new benchmarking method to objectively compare different upper airway resistance measurement methods by objectively differentiating between breaths with inspiratory flow limitation (high resistance) and non-limited breaths (low resistance). Resistance was measured at peak-Pes, at peak-flow, at the linear portion of a polynomial equation, as an area comparative and as average resistance for an inspiration. A total of 20 patients with systematic, gold-standard esophageal pressure and nasal airflow acquisition were analyzed and 109,955 breaths were automatically extracted and evaluated. Relative resistance values in relationship to a reference resistance value obtained during wakefulness were also analyzed. The peak-Pes measurement method obtained the highest separation index with significant (p < 0.001) differences to the other methods, followed by the area comparative and the peak-flow methods. As expected, average resistances were significantly (p < 0.001) lower for the non-IFL than for the IFL group. Hence, we recommend employing the peak-Pes for accurate upper airway resistance estimation.

  • Evaluación de la eficiencia de los músculos respiratorios durante un test de flujo incremental progresivo

     Sarlabous Uranga, Leonardo; Torres Cebrian, Abel; Fiz Fernández, José A.; Gea Guiral, Joaquim; Martínez-Llorens, Juana M.; Morera Prat, Josep Maria; Jane Campos, Raimon
    Congreso Anual de la Sociedad Española de Bioingeniería
    Presentation's date: 2011-11-18
    Presentation of work at congresses

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  • Bayes classification of snoring subjects with and without Sleep Apnea Hypopnea Syndrome, using a Kernel method

     Sola Soler, Jordi; Fiz, José A.; Morera Prat, Josep Maria; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2011-09-03
    Presentation of work at congresses

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  • Snoring analysis methods

     Fiz Fernández, José A.; Sola Soler, Jordi; Jane Campos, Raimon
    Medicina clínica
    Date of publication: 2011
    Journal article

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  • Usefulness of an Expandable Interbody Spacer for the Treatment of Foraminal Stenosis in Extremely Collapsed Disks Preliminary Clinical Experience With Endoscopic Posterolateral Transforaminal Approach

     Morgenstern, Rudolf; Jane Campos, Raimon; Morgenstern de Muller, Christian; Lee, Sang-ho
    Journal of spinal disorders and techniques
    Date of publication: 2011-12
    Journal article

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  • Microchannel enhanced neuron-computer interface: design, fabrication, biophysics of signal generation, signal strength optimization, and its applications to ion-channel screening and basic neuroscience research  Open access

     Wang, Ling
    Defense's date: 2011-12-15
    Department of Automatic Control, Universitat Politècnica de Catalunya
    Theses

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    En el presente trabajo, utilizamos técnicas de microfabricación, simulaciones numéricas, experimentos de electrofisiología para explorar la viabilidad en me- jorar la interface ordenador-neurona a través de microcanales, y la biofísica para la generación de señales en los dispositivos con microcanales. También demos- tramos que los microcanales pueden ser usados como una técnica prometedora con alto rendimiento en el muestreo automático de canales iónicos a nivel subce- lular. Finalmente, se ha diseñado, fabricado y probado el micropozo-microcanal como modificación adicional a los arreglos de multielectrodos, permitiendo una alta ganancia en la relación señal/ ruido (en inglés Signal to Noise Ratio SNR), y el registro de múltiples-lugares en poblaciones de baja densidad de redes neu- ronales del hipocampo in vitro. Primero, demostramos que son de alto rendimiento los microcanales de bajo costo con interface neurona-electrodo, para el registro extracelular de la activi- dad neuronal con baja complexidad, por periodos estables de larga duración y con alta ganancia SNR. En seguida, se realiza un estudio mediante experimentos y simulaciones nu- méricas de la biofísica para la generación de las señales obtenidas de los dispositi- vos con microcanales. Basados en los resultados, racionalizamos y demostramos como es que la longitud del canal (siendo 200 μm) y la sección transversal del microcanal (siendo 12 μm2) canaliza a los potenciales de acción para estar dentro del rango de milivolts. A pesar del bajo grado de complexidad envuelto en la fabricación y aplicación, los dispositivos con microcanales otorgan una sola media de valor SNR de 101 76, lo cual es favorablemente comparable con la SNR que se obtiene de desarrollos recientes que emplean electrodos curados con CNT y Si-NWFETs. Más aún, nosotros demostramos que el microcanal es una técnica promete- dora para el alto rendimiento del muestro automático de canales iónicos a nivel subcelular: (1) Información experimental y simulaciones numéricas sugieren que las señales registradas sólo afectan los parches membranales localizados dentro del microcanal o alrededor de 100 μm de las entradas del microcanal. (2) La transferencia de masa de los componentes químicos en los microcanales fue ana- lizada por experimentos y simulaciones FEM. Los resultados muestran que los microcanales que contienen glía y tejido neuronal pueden funcionar como barre- ra de fluido/química. Los componentes químicos pueden ser solamente aplicados a diferentes compartimentos a nivel subcelular. Finalmente, basado en simulaciones numéricas y resultados experimentales, se propone que del micropozo-microcanal, obtenido de la modificación de MEA (MWMC-MEA), la longitud óptima del canal debe ser 0,3 mm y la posición 1 óptima del electrodo intracanal, hacia la entrada más cercana del microcanal, debe ser 0,1 mm. Nosotros fabricamos un prototipo de MWMC-MEA, cuyo hoyo pasante sobre las películas de Polydimethylsiloxane (PDMS) fue microtrabajado a través de la técnica de grabados reactivos de plasma de iones. La baja densidad del cultivo (57 neuronas /mm2) en el MWMC-MEAs permitió que las neuronas vivieran al menos 14 días, con lo que la señal neuronal con la máxima SNR obtenida fue de 142. 2

    In this present work, we used microfabrication techniques, numerical simulations, electrophysiological experiments to explore the feasibility of enhancing neuron-computer interfaces with microchannels and the biophysics of the signal generation in microchannel devices. We also demonstrate the microchannel can be used as a promising technique for high-throughput automatic ion-channel screening at subcellular level. Finally, a microwell-microchannel enhanced multielectrode array allowing high signal-to-noise ratio (SNR), multi-site recording from the low-density hippocampal neural network in vitro was designed, fabricated and tested. First, we demonstrate using microchannels as a low-cost neuron-electrode interface to support low-complexity, long-term-stable, high SNR extracellular recording of neural activity, with high-throughput potential. Next, the biophysics of the signal generation of microchannel devices was studied by experiments and numerical simulations. Based on the results, we demonstrate and rationalize how channels with a length of 200 μm and channel cross section of 12 μm2 yielded spike sizes in the millivolt range. Despite the low degree of complexity involved in their fabrication and use, microchannel devices provided a single-unit mean SNR of 101 76, which compares favourably with the SNR obtained from recent developments employing CNT-coated electrodes and Si-NWFETs. Moreover, we further demonstrate that the microchannel is a promising technique for high-throughput automatic ion-channel screening at subcellular level: (1) Experimental data and numerical simulations suggest that the recorded signals are only affected by the membrane patches located inside the microchannel or within 100 μm to the microchannel entrances. (2) The mass transfer of chemical compounds in microchannels was analyzed by experiments and FEM simulations. The results show that the microchannel threaded by glial and neural tissue can function as fluid/chemical barrier. Thus chemical compounds can be applied to different subcellular compartments exclusively. Finally, a microwell-microchannel enhanced MEA (MWMC-MEA), with the optimal channel length of 0.3 mm and the optimal intrachannel electrode position of 0.1 mm to the nearest channel entrance, was proposed based on numerical simulation and experiment results. We fabricated a prototype of the MWMCMEA, whose through-hole feature of Polydimethylsiloxane film (PDMS) was micromachined by reactive-ion etching. The low-density culture (57 neurons/mm2) were survived on the MWMC-MEAs for at least 14 days, from which the neuronal signal with the maximum SNR of 142 was obtained.

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    The natural history of the sleep and respiratory engineering track at EMBC 1988 to 2010  Open access

     Leder, Ron S.; Schlotthauer, Gaston; Penzel, Thomas; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2010-09
    Presentation of work at congresses

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    Sleep science and respiratory engineering as medical subspecialties and research areas grew up side-by-side with biomedical engineering. The formation of EMBS in the 1950's and the discovery of REM sleep in the 1950's led to parallel development and interaction of sleep and biomedical engineering in diagnostics and therapeutics. Over the last 60 years, sleep investigators have relied on biomedical engineering to home-brew the equipment they used to measure physiology during sleep, because sensors and automatic sleep analysis and interpretation systems were too innovative to be available from traditional commercial sources. The Sleep and Respiratory Engineering and related tracks of EMBC, between 1988 and 2010, have presented many papers on this topic including novel techniques of sleep interpretation and new equipment for diagnostics, portable and ambulatory measurement, monitoring, and therapeutics. In this research, we summarize the activity at EMBC related to Sleep and breathing from an historical perspective, showing the number of publications and special sessions devoted to sleep and related topics.

  • Interpretation of the approximate entropy using fixed tolerance values as a measure of amplitude variations in biomedical signals

     Sarlabous Uranga, Leonardo; Torres Cebrian, Abel; Fiz Fernández, José A.; Gea Guiral, Joaquim; Martínez Llorens, Juana María; Morera Prat, Josep Maria; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2010-09-03
    Presentation of work at congresses

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    A new method for the quantification of amplitude variations in biomedical signals through moving approximate entropy is presented. Unlike the usual method to calculate the approximate entropy (ApEn), in which the tolerance value (r) varies based on the standard deviation of each moving window, in this work ApEn has been computed using a fixed value of r. We called this method, moving approximate entropy with fixed tolerance values: ApEnf. The obtained results indicate that ApEnf allows determining amplitude variations in biomedical data series. These amplitude variations are better determined when intermediate values of tolerance are used. The study performed in diaphragmatic mechanomyographic signals shows that the ApEnf curve is more correlated with the respiratory effort than the standard RMS amplitude parameter. Furthermore, it has been observed that the ApEnf parameter is less affected by the existence of impulsive, sinusoidal, constant and Gaussian noises in comparison with the RMS amplitude parameter.

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    Analysis of QRS loop in the vectorcardiogram of patients with Chagas' disease  Open access

     Correa, Raul; Laciar, Eric; Arini, Pedro; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation of work at congresses

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    In the present work, we have studied the QRS loop in the Vectorcardiogram (VCG) of 95 chronic chagasic patients classified in different groups (I, II and III) according to their degree of myocardial damage. For comparison, the VCGs of 11 healthy subjects used as control group (Group O) were also examined. The QRS loop was obtained for each patient from the XYZ orthogonal leads of their High-Resolution Electrocardiogram (HRECG) records. In order to analyze the variations of QRS loop in each detected beat, it has been proposed in this study the following vectorcardiographic parameters a) Maximum magnitude of the cardiac depolarization vector, b) Volume, c) Area of QRS loop, d) Ratio between the Area and Perimeter, e) Ratio between the major and minor axes of the QRS loop and f) QRS loop Energy. It has been found that one or more indexes exhibited statistical differences (p<;0.05) between groups 0-II, O-III, I-II, I-III and II-III. We concluded that the proposed method could be use as complementary diagnosis technique to evaluate the degree of myocardial damage in chronic chagasic patients.

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    Entropía aproximada móvil con valores de tolerancia fijos como medida de las variaciones de amplitud en señales biomédicas  Open access

     Sarlabous Uranga, Leonardo; Torres Cebrian, Abel; Fiz Fernández, José A.; Gea Guiral, Joaquim; Martínez Llorens, Juana María; Jane Campos, Raimon; Morera Prat, Josep Maria
    Congreso Anual de la Sociedad Española de Ingeniería Biomédica
    Presentation's date: 2010-11-24
    Presentation of work at congresses

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    En este trabajo se presenta un nuevo método para cuantificar las variaciones de amplitud en señales biomédicas empleando la entropía aproximada (ApEn) en ventanas móviles y con valores de tolerancia (r) fijos. Los valores límites de r se corresponden con el máximo y mínimo de la desviación estándar obtenida en todas las ventanas móviles. A esta nueva métrica se le ha denominado ApEnf: entropía aproxima con valores de r fijos. ApEnf se aplicó en señales mecanomiográficas (MMG) diafragmáticas registradas en perros, para valores de r entre 0.01 y 0.4. Los resultados obtenidos indican que al aumentar el valor de r (hasta un cierto valor) las variaciones de amplitud son mejor definidas (señales menos ruidosas), aumentando así la correlación con la señal de presión inspiratoria. Además, en presencia de ruidos de tipo impulsional, sinusoidal y gaussiano, ApEnf para valores de r medios es menos afectado que el RMS.

    Postprint (author’s final draft)

  • Noninvasive evaluation of the respiratory muscular function by means of mechanomyographic signals of the diaphragm muscle in COPD patients

     Torres Cebrian, Abel; Fiz, José Antonio; Sarlabous Uranga, Leonardo; Gea Guiral, Joaquim; Martínez Llorens, Juana María; Morera Prat, Josep Maria; Jane Campos, Raimon
    European Respiratory Society Annual Congress
    Presentation's date: 2010-09
    Presentation of work at congresses

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  • Study of periodic breathing in chronic heart failure patients based on correntropy

     Garde Martinez, Ainara; Giraldo Giraldo, Beatriz F.; Jane Campos, Raimon
    Symposium on Bioengineering and Nanomedicine
    Presentation's date: 2010-06
    Presentation of work at congresses

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    Correntropy-based nonlinearity test applied to patients with chronic heart failure  Open access

     Garde Martinez, Ainara; Sörnmo, Leif; Jane Campos, Raimon; Giraldo Giraldo, Beatriz F.
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2010-09
    Presentation of work at congresses

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    In this study we propose the correntropy function as a discriminative measure for detecting nonlinearities in the respiratory pattern of chronic heart failure (CHF) patients with periodic or nonperiodic breathing pattern (PB or nPB, respectively). The complexity seems to be reduced in CHF patients with higher risk level. Correntropy reflects information on both, statistical distribution and temporal structure of the underlying dataset. It is a suitable measure due to its capability to preserve nonlinear information. The null hypothesis considered is that the analyzed data is generated by a Gaussian linear stochastic process. Correntropy is used in a statistical test to reject the null hypothesis through surrogate data methods. Various parameters, derived from the correntropy and correntropy spectral density (CSD) to characterize the respiratory pattern, presented no significant differences when extracted from the iteratively refined amplitude adjusted Fourier transform (IAAFT) surrogate data. The ratio between the powers in the modulation and respiratory frequency bands R was significantly different in nPB patients, but not in PB patients, which reflects a higher presence of nonlinearities in nPB patients than in PB patients.

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    Evaluación de la actividad de los músculos inspiratorios mediante señales mecanomiográficas en pacientes con EPOC durante un protocolo de carga incremental  Open access

     Torres Cebrian, Abel; Sarlabous Uranga, Leonardo; Fiz Fernández, José A.; Gea Guiral, Joaquim; Martínez Llorens, Juana María; Morera Prat, Josep Maria; Jane Campos, Raimon
    Congreso Anual de la Sociedad Española de Ingeniería Biomédica
    Presentation's date: 2010-11-24
    Presentation of work at congresses

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    El estudio de señales mecanomiográficas (MMG) de músculos respiratorios es una técnica prometedora para evaluar el esfuerzo muscular respiratorio. En este trabajo se han analizado las señales MMG del músculo diafragma derecho e izquierdo registradas en pacientes con Enfermedad Pulmonar Obstructiva Crónica (EPOC) durante un protocolo de carga incremental. La población de estudio está compuesta por un grupo de 6 pacientes con EPOC severa (FEV1>50% ref and DLCO<50% ref). Se ha obtenido una alta correlación positiva entre la presión inspiratoria máxima (PImax) desarrollada y diferentes parámetros de amplitud de las señales MMG izquierda y derecha (RMS, izquierda: 0.68±0.11 – derecha: 0.69±0.12; entropía de Rényi, izquierda: 0.73±0.10 – derecha: 0.77±0.08; Lempel-Ziv Multiestado, izquierda: 0.73±0.17 – derecha: 0.74±0.08), y una correlación negativa entre la PImax y la frecuencia máxima de la señal MMG (izquierda: -0.39±0.19 – derecha: -0.65±0.09). Además hemos encontrado que la pendiente de la evolución con el incremento de carga de los parámetros de amplitud de la señal MMG, tiene una correlación positiva con el parámetro funcional respiratorio %FEV1/FVC de los 6 pacientes EPOC analizados (RMS, izquierda: 0.38 – derecha: 0.41; entropía de Rényi, izquierda: 0.45 – derecha: 0.63; Lempel-Ziv Multiestado, izquierda: 0.39 – derecha: 0.64). Estos resultados sugieren que la información proporcionada por las señales MMG podría ser utilizada para evaluar el esfuerzo respiratorio y la eficiencia muscular en pacientes EPOC.

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    Noninvasive measurement of inspiratory muscle performance by means of diaphragm muscle mechanomyographic signals in COPD patients during an incremental load respiratory test  Open access

     Torres Cebrian, Abel; Sarlabous Uranga, Leonardo; Fiz Fernández, José A.; Gea Guiral, Joaquim; Martínez Llorens, Juana María; Morera Prat, Josep Maria; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2010-09-03
    Presentation of work at congresses

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    The study of mechanomyographic (MMG) signals of respiratory muscles is a promising noninvasive technique in order to evaluate the respiratory muscular effort and efficiency. In this work, the MMG signal of the diaphragm muscle it is evaluated in order to assess the respiratory muscular function in Chronic Obstructive Pulmonary Disease (COPD) patients. The MMG signals from left and right hemidiaphragm were acquired using two capacitive accelerometers placed on both left and right sides of the costal wall surface. The MMG signals and the inspiratory pressure signal were acquired while the COPD patients carried out an inspiratory load respiratory test. The population of study is composed of a group of 6 patients with severe COPD (FEV1>50% ref and DLCO<50% ref). We have found high positive correlation coefficients between the maximum inspiratory pressure (IPmax) developed in a respiratory cycle and different amplitude parameters of both left and right MMG signals (RMS, left: 0.68±0.11 – right: 0.69±0.12; Rényi entropy, left: 0.73±0.10 – right: 0.77±0.08; Multistate Lempel- Ziv, left: 0.73±0.17 – right: 0.74±0.08), and negative correlation between the Pmax and the maximum frequency of the MMG signal spectrum (left: -0.39±0.19 – right: -0.65±0.09). Furthermore, we found that the slope of the evolution of the MMG amplitude parameters, as the load increases during the respiratory test, has positive correlation with the %FEV1/FVC pulmonary function test parameter of the six COPD patients analyzed (RMS, left: 0.38 – right: 0.41; Rényi entropy, left: 0.45 – right: 0.63; Multistate Lempel-Ziv, left: 0.39 – right: 0.64). These results suggest that the information provided by MMG signals could be used in order to evaluate the respiratory effort and the muscular efficiency in COPD patients.

    Postprint (author’s final draft)

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    Regular and non regular snore features as markers of SAHS  Open access

     Gil De Mesquita, Joana Margarida; Fiz, José Antonio; Sola Soler, Jordi; Morera Prat, Josep Maria; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2010-09
    Presentation of work at congresses

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    Sleep Apnea-Hypopnea Syndrome (SAHS) diagnosis is still done with an overnight multi-channel polysomnography. Several efforts are being made to study profoundly the snore mechanism and discover how it can provide an opportunity to diagnose the disease. This work introduces the concept of regular snores, defined as the ones produced in consecutive respiratory cycles, since they are produced in a regular way, without interruptions. We applied 2 thresholds (THadaptive and THmedian) to the time interval between successive snores of 34 subjects in order to select regular snores from the whole all-night snore sequence. Afterwards, we studied the effectiveness that parameters, such as time interval between successive snores and the mean intensity of snores, have on distinguishing between different levels of SAHS severity (AHI (Apnea-Hypopnea Index)<5h-1, AHI<10 h-1, AHI<15h-1, AHI<30h-1). Results showed that THadaptive outperformed THmedian on selecting regular snores. Moreover, the outcome achieved with non-regular snores intensity features suggests that these carry key information on SAHS severity.

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    Automatic non-invasive differentiation of obstructive and central hypopneas with nasal airflow compared to esophageal pressure  Open access

     Morgenstern de Muller, Christian Rudolf; Schwaibold, Matthias; Randerath, Winfried J.; Bolz, Armin; Jane Campos, Raimon
    IEEE Engineering in Medicine and Biology Society
    Presentation's date: 2010-09
    Presentation of work at congresses

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    The differentiation of obstructive and central respiratory events is a major challenge in the diagnosis of sleep disordered breathing. Esophageal pressure (Pes) measurement is the gold-standard method to identify these events but its invasiveness deters its usage in clinical routine. Flattening patterns appear in the airflow signal during episodes of inspiratory flow limitation (IFL) and have been shown with invasive techniques to be useful to differentiate between central and obstructive hypopneas. In this study we present a new method for the automatic non-invasive differentiation of obstructive and central hypopneas solely with nasal airflow. An overall of 36 patients underwent full night polysomnography with systematic Pes recording and a total of 1069 hypopneas were manually scored by human experts to create a goldstandard annotation set. Features were automatically extracted from the nasal airflow signal to train and test our automatic classifier (Discriminant Analysis). Flattening patterns were non-invasively assessed in the airflow signal using spectral and time analysis. The automatic non-invasive classifier obtained a sensitivity of 0.71 and an accuracy of 0.69, similar to the results obtained with a manual non-invasive classification algorithm. Hence, flattening airflow patterns seem promising for the noninvasive differentiation of obstructive and central hypopneas.