Jose García - Academia.edu (original) (raw)

Papers by Jose García

2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society

In this work we have analyzed changes in the heart rate variability (HRV) during exercise test co... more In this work we have analyzed changes in the heart rate variability (HRV) during exercise test comparing them with the ST deviation criteria to improve the diagnostic value of the exercise test. Coronary angiography was considered as gold standard to establish the classification of patients in two groups (ischemic and non-ischemic). ST deviations and HRV indexes were automatically measured and used as independent factors in discriminant analysis to find those more useful to classify both groups. Several approaches were performed starting with different sets of variables. Results showed that by using only the ST indexes it is possible to correctly classify 76% of patients. The inclusion of HRV indexes improves the exactness up to 84%. The very high frequency (0.4 to 1 Hz) at the stress peak has shown to have diagnostic value. Adding the age and the maximum heart rate the exactness goes up to 87.4% (sens. 85.5%, spec. 89.1%), close to that obtained by exercise echocardiography or exercise nuclear imaging.

Lecture Notes in Computer Science

The development of e-Health services in rural environments, where broadband networks are usually ... more The development of e-Health services in rural environments, where broadband networks are usually not accessible, requires a specific analysis of available resources to improve Quality of Service (QoS) management. This work quantifies the maximum number of simultaneous users that fulfill the specific QoS levels in common e-Health services, including both store-andforward and real-time telemedicine applications. The analysis also proposes variations in the modelling of traffic distributions regarding the number of multiplexed users. The results obtained in this study permit an accurate users dimensioning, which is necessary to optimize the performance and to guarantee the QoS requirements in this kind of services where network resources are limited.

2006 International Conference of the IEEE Engineering in Medicine and Biology Society, 2006

The development of e-Health services in rural environments, where broadband accesses are usually ... more The development of e-Health services in rural environments, where broadband accesses are usually not available, requires a specific analysis of available resources to improve the management of Quality of Service (QoS). This work studies the sharing of resources among several users and the system efficiency in rural areas, guaranteeing QoS. The results obtained show that, with the premises considered in this study, a rural centre can establish a maximum number of simultaneous real-time services with the hospital, which varies between 2 and 3 for each 64kb/s of available link capacity.

Nowadays, one of the main issues of Human Computer Interaction (HCI) studies is the study of inte... more Nowadays, one of the main issues of Human Computer Interaction (HCI) studies is the study of interactions established between people and new technologies. Nevertheless, the research in HCI has been mainly focused from a cognitive point of view, and most studies don't consider other variables related to the social impact of technology. In this paper we present an interdisciplinary perspective through its application in designing new e-Health services in the area of cardiology. From this standpoint and in order to extract the maximum benefit from these new services, it is essential to accurately define not only technical requirements and network resources management, but also user requirements and all those contextual particularities of the scenarios where these services could be implemented. In this way, we propose an interdisciplinary methodology that provides us a field of working in which technical and psychosocial qualitative knowledge influence each other. Thus, the results obtained in specific scenarios of implementation for a telecardiology service allow new user-based designs that can be directly integrated in the medical practice in an efficient way.

This study presents a new approach to improve the echocardiogram transmissions over WiMAX network... more This study presents a new approach to improve the echocardiogram transmissions over WiMAX networks. Using a compression method based on visualization modes and a reliable method that adapts to the channel conditions, overall performance results are improved compared to classical approaches. The echocardiogram transmission using a compression method based on visualization modes requires lower bandwidth than without considering visualization modes. Furthermore, if the proposed reliability method is also used, the echocardiogram is more often visualized with adequate clinical quality than compressing the echocardiogram without distinguishing the visualization modes and without using a reliability method for the available dataset. The reduction in the bandwidth ranges from 29 kbps to 166 kbps for the simulated scenarios.

IEEE-EMBS International Conference on Biomedical and Health Informatics (BHI), 2014

ABSTRACT This paper proposes a cryptosteganographic coding for signals (e.g. ECGs), periodic meas... more ABSTRACT This paper proposes a cryptosteganographic coding for signals (e.g. ECGs), periodic measurements (e.g. oxygen in blood, body temperature) and contextual data (e.g. allergies, medication of the user) gathered in body area networks. This information is acquired by a device with multiple interfaces and sensors connected to it. The acquiring device compresses the signals with the SPIHT coder; protects the measurements and the data; and embeds them within the signals in the compressed domain. Next, it performs partial encryption on the signals. Finally, the resulting encoded information is forwarded to one or several devices for its visualization. The access to the signals, the measurements and the data is limited according to the professional role of the consulting user. Tested with ECG stress tests, this coding compresses the transmission bandwidth/storage space typ. by 2.8-7.8, and its architecture operates in real-time with overall delays of 2-2.7s. Finally, this coding is also suitable for networks acquiring other signals, such as EEG or PPG.

Topics in Biomedical Engineering

Page 1. 293 RESILIENT ECG WAVELET CODING FOR WIRELESS REAL-TIME TELECARDIOLOGY APPLICATIONS Álvar... more Page 1. 293 RESILIENT ECG WAVELET CODING FOR WIRELESS REAL-TIME TELECARDIOLOGY APPLICATIONS Álvaro Alesanco * , José García, Salvador Olmos, and Robert SH Istepanian 1. INTRODUCTION Mobile telemedicine ...

Journal of telemedicine and telecare, 2007

We propose a telemedicine framework for remote and manufacturer independent pacemaker (PM) follow... more We propose a telemedicine framework for remote and manufacturer independent pacemaker (PM) follow-up. The main goal is to provide the caregiver at the point-of-care with an efficient screening method to identify possible malfunction of the pacing system in collaboration with the specialist at the PM clinic. The concept was evaluated in a clinical trial on 44 patients (mean age 76 years). A total of 62 electrocardiogram (ECG) recordings were transmitted using a mobile PM follow-up unit. Using the automatic classification algorithm, 32 PMs were classified as…

2009 Fourth International Multi-Conference on Computing in the Global Information Technology, 2009

Continuous technological innovations are bringing new opportunities to healthcare applications. A... more Continuous technological innovations are bringing new opportunities to healthcare applications. Although these improvements apply to most of its different fields, outstanding results are being achieved in medical devices interoperability, oriented to ubiquitous solutions including wearable devices, focused to the new paradigm of Personal Health (p-Health). These evolutions can improve the quality of the patient's care, increase the user's interaction and, furthermore, lead to new medical use cases based on Ambient Assisted Living, home monitoring of elderly, heart failure, chronic, under palliative care or patients who have undergone surgery, urgencies and emergencies, or even fitness auto-control and health follow-up. Furthermore, in order to assure p-Health applications to be fully compatible with larger global e-Health systems in terms of terminology homogenization or plug-and-play operation, proposed solutions have to be based on interoperability. In this paper, recent innovative advances in biomedical engineering applied to standard-based telemedicine solutions are detailed.

Journal of Medical Engineering & Technology, 1998

The ST-T segment of the surface ECG re ects cardiac repolarization, and is quite sensitive to a n... more The ST-T segment of the surface ECG re ects cardiac repolarization, and is quite sensitive to a number of pathological conditions, particularly ischaemia. ST-T changes generally a ect the entire waveshape, and are inadequately characterized by single features such as depression of the ST segment at one particular point. Metrics which represent overall waveshape should provide more sensitive indicators of ST-T wave abnormalities, particularly when they are subtle, intermittent or periodic. This study discusses a Karhunen-Loeve T ransform (KLT) technique for the analysis of the ST-T waveform. The KL technique was used to analyse the ST-T complexes in the ESC ST-T database. KL coe cients were plotted as a function of time, and were e ective in detection of transient ischemic episodes. Twenty percent of the records showed bursts of periodic ischaemia suggesting local vascular instability. A comparison between kland ST depression series has shown the KL technique as more adequate to the study of ST-T complex variations. Using the Kl series, an ischaemia detector has been developed based on a resampled, ltered, and di erentiated KL series. This technique obtains a sensitivity o f 65% and a speci city o f 5 4 %. These low v alues can be due to shifts of the electrical axis which are detected as ischaemic changes, real ischaemic episodes that were not annotated with the protocol used at the European ST-T database or erroneous detections. An increase in sensitivity can be obtained at the expense of a decrease in the positive predictive v alue and thus becomes a useful technique for previous scanning of the ECG record and posterior review for the expert. The technique has also been used to monitor patients during a PTCA process, demostrating that this technique allows us to monitor PTCA-induced ischaemia. A ne analysis has shown that in some cases a repetitive oscillatory behavior appears, lasting for a period of around 20 seconds, and highly related to the oscillatory behavior of the HR. In other cases, transient c hanges in KL series with salves behavior associated with the injection of contrast are shown on the ST-T waveform. We conclude that the KL-based analysis of the ST-T segment is a robust and sensitive t e c hnique, with considerable advantages over single feature measures in characterizing the subtle waveform changes which m a y be of importance in clinical risk detection.

Journal of Electrocardiology, 2000

The time course of changes in the ECG as a result of myocardial ischemia induced during prolonged... more The time course of changes in the ECG as a result of myocardial ischemia induced during prolonged coronary angioplasty h a ve been studied. We h a ve analyzed the ECG evolution during the occlusion in terms of the Ischemic Changes Sensor (I C S) which is a parameter that describes the capacity o f di erent indexes to detect induced changes. Traditional indexes at speci c time locations (ST level, T w ave amplitude and position, and durations of QT interval and QRS complex) and global indexes (based on the Karhunen-Lo eve transform (KLT) as applied to the QRS complex, ST-T complex, ST segment a n d T w ave) have been considered. The global indexes better detected ischemic changes than the traditional indexes did: the most sensitive were the index for the ST-T complex (89%) in the KLT-derived group, and for the ST level (61%) in the traditional group. Changes in the ventricular repolarization period usually appeared earlier (77% of patients) than changes in the depolarization period (23% of patients). A similar percentage of patients exhibited the earliest ischemic changes in t h e T w ave (41%) and in the ST segment (36%). The evolution of the I C Sparameters showed that the majority (60%) of the total changes occurred during the rst minute of occlusion. The results suggest that the use of global ECG indexes better re ect ischemic changes than do traditional indexes, such as the ST segment deviation.

IEEE Transactions on Information Technology in Biomedicine, 2006

IEEE Transactions on Biomedical Engineering, 2012

This study presents a methodology to transmit 2D echocardiogram video over WiMAX networks in real... more This study presents a methodology to transmit 2D echocardiogram video over WiMAX networks in real-time. Before transmission the echocardiogram has to be compressed. In order to compress the echocardiogram the 3D SPIHT algorithm was used. To guarantee the clinical quality of the compressed echocardiogram a clinical evaluation of the compressed echocardiogram was carried out. The evaluation yielded the minimum transmission rate necessary for an accurate diagnosis, 200 kbps. However, the channel produces errors and distorts the video, so in order to reduce these errors a reliable application protocol was proposed using a hybrid solution in which retransmission was combined with Forward Error Correction (FEC) techniques. The transmission was simulated in WiMAX networks. The proposed protocol achieved 100 % of time with guaranteed clinical quality (200 kbps) for bit error rate up to 0.254, being this value lower than for the retransmissions and FEC working separately.

ABSTRACT Presentamos a través de este trabajo, la evaluación y valoración del impacto ocasionado ... more ABSTRACT Presentamos a través de este trabajo, la evaluación y valoración del impacto ocasionado sobre pacientes y el proceso organizativo, tras el desarrollo e implantación de un nuevo servicio de tele-electroencefalografía (tele-EEG) entre la Fundación Hospital de Calahorra (FHC) y el Hospital San Pedro de Logroño (HSP), ambos situados en la comunidad autónoma de La Rioja (España). El servicio de Tele-EEG permite que un especialista del Departamento de Neurofisiología del HSP controle y supervise en tiempo real la prueba de video EEG que se realiza a los pacientes en la FHC y pueda acceder a la revisión posterior en tiempo diferido. Este sistema permite proporcionar los mismos resultados diagnósticos que el sistema convencional, mejorando la prestación y el acceso a la población atendida en un hospital comarcal, reduciendo los costes por desplazamientos y disminuyendo el tiempo transcurrido hasta la consulta sucesiva del médico peticionario.

Computer Methods and Programs in Biomedicine, 2007

… Topic Conference on …, 2006

A telecardiology framework for research and clinical decision support is presented. The telemedic... more A telecardiology framework for research and clinical decision support is presented. The telemedicine framework provides with connection to three participant sites: the physician at the point-of-care, the remote information centre and the specialized cardiologist. At the point of care, a physician acquires the ECG and other relevant information during the clinical intervention and sends it to the information server. Every ECG file received is stored in the file server, linked to the patient database and processed by the MATLABbased tools in the processing server, which automatically generates a results report and informs the cardiologist of this fact. The system has been applied in the study of HRV in patients undergoing haemodialysis. In this particular case, the report consists of trends of time-domain and frequency-domain HRV indexes along dialysis and other supplementary information. The framework has been evaluated by patients and hospital personnel, who valued very positively the system. The designed framework has been shown as an efficient and helpful tool for clinical diagnosis support.

Abstract—The present paper describes a new least–squares error criterion for the alignment of two... more Abstract—The present paper describes a new least–squares error criterion for the alignment of two vectorcardiographic (VCG) loops. The criterion is developed to handle certain conditions related to changes in body position, large differences in QRS amplitude or high noise levels. Several examples are included which illustrate the performance of the method in terms of, eg, parameter estimate accuracy. Keywords—Least–squares estimation, loop alignment, VCG loop.

Revista de Neurología, 2006