Obtención de micropotenciales cardíacos latido a latido por vía superficial

Para la detección no invasiva de la señal del haz de his latido a latido, es necesario que el nivel de ruido e interferencias presentes en el registro sea extremadamente bajo. El estudio del entorno de medida donde se realizan los registros y la clasificación de las fuentes de ruido e interferencia, así como el estudio de su influencia en el registro, permite desarrollar técnicas de reducción de ruido e interferencias que facilitan la detección visual de dicha señal. Las técnicas de reducción de ruido e interferencias propuestas son: la relajación del paciente, la utilización de las derivaciones con la mayor relación señal a ruido, el uso de electrodos apantallados y activos, el apantallamiento del paciente mediante una tela conductora, el filtrado adaptativo y el promediado espacial de señal. La aplicación de estas técnicas ha permitido detectar de la señal de his en un porcentaje elevado de los casos estudiados. La señal detectada en la superficie del cuerpo no puede competir con las obtenidas mediante registros intracavitarios, debido a su menor amplitud y a que no se consigue la detección en el 100% de los casos. No obstante, el bajo coste del equipo diseñado y la simplicidad de las técnicas de procesado de señal aplicadas hacen que la detección superficial de la señal pueda ser valida como una prueba diagnostica extrahospitalaria

RFID systems in medical environment: EMC issues

RFID is a promising technology in the healthcare area in order to improve patient safety and increase efficiency and reduce costs in the daily healthcare work. This paper analyzes the available literature regarding both interference of RFID systems in medical equipment and the interferences of medical equipment on RFID systems. The conclusion of this analysis is that is necessary to develop standards in order to protect medical equipment from RFID interferences, and standards to plan the deployment of RFID installations taking into account electromagnetic compatibility issues.Postprint (published version

A comprehensive model for power line interference in biopotential measurements

Power line interference is a major problem in high-resolution biopotential measurements. Because interference coupling is mostly capacitive, shielding electrode leads and a high common-mode rejection ratio (CMRR) are quite effective in reducing power-line interference but do not completely eliminate it. We propose a model that includes both interference external to the measuring system and interference coming from its internal power supply. Moreover, the model considers interference directly coupled to the measuring electrodes, because, as opposed to connecting leads, electrodes are not usually shielded. Experimental results confirm that reducing interference coupled through electrodes yields a negligible interference. The proposed model can be applied to other differential measurement systems, particulary those involving electrodes or sensors placed far apart.Peer Reviewe

RFID system evaluation against radiated transient noise

In this paper a radiofrequency identification system according to standard ISO/IEC 14443 type-B is evaluated in presence of transient noise. This real time communication system working at 13.56 MHz is interfered in a controlled environment by different transient bursts varying their level, frequency and duration. The transient burst interference is applied in an AC main wire close to the system and the effect over the digital communication system is evaluated using two different methods. The first one is observing directly an RFID equipment in presence of transient signals, and the second one is capturing the interference in time domain an evaluating its effect by means of simulation. The RFID system is affected by these transient noises causing different types of errors. It is shown that it is essential to measure and evaluate in time domain the transient phenomena to ensure that the RFID system do not have susceptibility problems.Peer ReviewedPostprint (published version

Understanding electrosurgical unit perturbations in order to address hospital operating room electromagnetic compatibility

We analyze the radiated emissions from a low power electrosurgical unit (ESU). Measurements at a 3-meter distance are performed in order to find a suitable measurement setup intended to reproduce realistically the real working ESU behavior in a test lab. The broad-band and narrow-band characteristics of the perturbation are studied in order to address the other equipment immunity.Peer Reviewe

A new and fast index for the quantification of short range self-similarity in RR time series

We propose a new and very fast index (the frequency of sign changes of the mirrored differences or fscmd) with good correlation with the short range scaling exponent ( Ｒ) estimated among scales 4 to 16 of the DFA. fscmd computes the relative number of sign changes of the difference of the RR time series minus their corresponding reversed RR time series after a moving average detrending procedure is applied using a window of 30 samples. Linear regression results with simulated time series with Fractional Brownian Noise and with actual time series using the Fantasia (FT), Normal Sinus Rhythm RR time series (NSR) and Congestive Heart Failure RR interval (CHF) databases after artifact correction show good agreement between fscmd and Ｒ. Finally, Mann-Whitney Rank Sum tests applied to Ｒ and fscmd when comparing NSR and CHF databases show very significant differences (p<0.001) between groups for both indices.Postprint (published version

Driver drowsiness detection based on respiratory signal analysis

Drowsy driving is a prevalent and serious public health issue that deserves attention. Recent studies estimate around 20% of car crashes have been caused by drowsy drivers. Nowadays, one of the main goals in the development of new advanced driver assistance systems is the trustworthy drowsiness detection. In this paper, a drowsiness detection method based on changes in the respiratory signal is proposed. The respiratory signal, which has been obtained using an inductive plethysmography belt, has been processed in real-time in order to classify the driver’s state of alertness as drowsy or awake. The proposed algorithm is based on the analysis of the respiratory rate variability (RRV) in order to detect the fight against to fall asleep. Moreover, a method to provide a quality level of the respiratory signal is also proposed. Both methods have been combined to reduce false alarms due to changes of measured RRV associated not to drowsiness but body movements. A driving simulator cabin has been used to perform the validation tests and external observers have rated the drivers’ state of alertness in order to evaluate the algorithm performance. It has been achieved a specificity of 96.6%, sensitivity of 90.3% and Cohen’s Kappa agreement score of 0.75 on average across all subjects through a leave-one-subject-out cross-validation. A novel algorithm for driver’s state of alertness monitoring through the identification of the fight against to fall asleep has been validated. The proposed algorithm may be a valuable vehicle safety system to alert drowsiness while drivingPeer ReviewedPostprint (published version

Estimation of the uncertainty in time domain indices of RR time series

A method for estimating the uncertainty in time-domain indices of RR time series is described. The method relies on the central limit theorem that states that the distribution of a sample average of independent samples has an uncertainty that asymptotically approaches to the sample standard deviation divided by the square root of the number of samples. Because RR time series cannot be characterized by a set of independent samples, we propose to estimate the uncertainty of indices by computing them in blocks that satisfy that the obtained partial indices are independent. We propose a methodology to search sets of independent partial indices and apply this methodology to the estimation of the uncertainty in the mean RR, SDRR, and r-msDD indices. The results show that the uncertainty can be higher than the 10% of the index for the SDRR and even higher for the r-msDD. Moreover, a statistical test for the difference of two indices is proposed.Peer Reviewe

Transient perturbation analysis in digital radio

This paper presents a new simulation methodology to study the effect of radiated transient disturbances on digital communication systems. The procedure is divided in two stages. In the first one, FDTD numerical simulation is used to determine the transient levels coupled to the antennas. In the second stage, these levels are analyzed by means of a signal processing simulation software to determine the degradation caused in the system. The procedure is applied to a DAB system in car when a radiated interference is generated by a transient in a vehicle cable. The results show that the amplitude of the radiated transient coupled signal is a key parameter, but it is also essential to take into account other parameters such as burst duration and frequency.Postprint (published version

Characterization of time domain EM field double-loaded curved loop probe

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksIn this paper, we present and analyze the performance of a double-loaded curved loop probe to measure simultaneously electric and magnetic fields (EMF). The aim is to construct a probe that can be fitted to non-planar structures and have a proper response to EMF. The curved probe is studied in comparison with well-known planar probes, which have been verified and used previously. The time-domain data obtained through EM simulation allow us to identify if the probe's response is suitable although its geometry. Finally, the probe has been constructed and evaluated with experimental test, measuring and validating the conclusions find out by the EM simulation.This work was supported in part by the EURAMET 15RPT01 research project (the EMPIR is jointly funded by the EMPIR participating countries within EURAMET and the European Union), by the Spanish “Ministerio de Economía, Industria y Competitividad,” under project TEC2016-79214-C3-2-R (AEI/FEDER, UE), by the “Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement de la Generalitat de Catalunya” and the European Social Fund and The author(s) would like to acknowledge the contribution of the COST Action IC1407 ‘ACCREDIT’.Peer ReviewedPostprint (author's final draft