SISTEMA DE ADQUISICIÓN DE SEÑALES FOTOPLETISMOGRÁFICAS PARA LA ESTIMACIÓN NO INVASIVA DE GLUCOSA EN SANGRE (PHOTOPLETHYSMOGRAPHY SIGNAL ACQUISITION SYSTEM FOR NONINVASIVE BLOOD GLUCOSE ESTIMATION)

Resumen La diabetes mellitus (DM) es un trastorno metabólico y una de las principales causas de muerte en México y a nivel mundial. Las personas con DM requieren un monitoreo frecuente de sus niveles de glucosa a fin de evitar complicaciones. Actualmente, el método comúnmente utilizado se realiza mediante punciones en las yemas de los dedos para obtener una muestra de sangre a analizar, lo cual conlleva el riesgo de infecciones por la toma constante de muestras. Esta investigación propone un sistema de adquisición de señales fotopletismográficas con un LED IR a 940 nm capaz de interactuar con la molécula de la glucosa considerando las condiciones de peso del participante. Los resultados son clínicamente aceptables demostrando una alta confiabilidad del sistema propuesto respecto a un glucómetro convencional, logrando una de hasta 0.9739 y estimaciones en las regiones A y B en el análisis de la rejilla de errores de Clarke. Palabras Clave: Infrarrojo cercano, Diabetes Mellitus, Fotopletismografía, Glucómetro, No invasivo. Abstract Diabetes mellittus (DM) is a metabolic disorder and one of the main causes of death in Mexico and worldwide. People with DM require frequent monitoring of their glucose levels to avoid complications. Currently, the commonly used method it’s performed by punctures on the fingertips to obtain a sample of blood to be analyzed, this carries de risk of infections due to constant sampling. This research proposes a system for acquiring photoplethysmographic signals with an IR LED at 940 nm capable of interacting with the glucose molecule considering the weight conditions of the participant. The results are clinically acceptable, demonstrating a high reliability of the proposed system compared to a conventional glucometer, achieving an of up to 0.9739 and estimates in regions A and B in the Clarke error grid analysis. Keywords: Near Infrarred, Diabetes Mellitus, photopletysmography, Glucometer, non-invasive

Monitor de señales de electrocardiografía y frecuencia cardiaca mediante un teléfono móvil con el protocolo de comunicación Bluetooth

Objetivo: Desarrollar un equipo de monitoreo de señales de electrocardiografía (ECG) y frecuencia cardiaca (FC) portátil, comunicado con un teléfono móvil mediante el protocolo de comunicación Bluetooth (BT), para su visualización en pantalla. Métodos: Se diseñó un sistema de monitoreo que en su sección electrónica realiza la adquisición de la señal de ECG, así como su amplificación, filtrado, conversión analógica a digital y transmisión por BT del ECG y la FC. Se desarrollaron dos programas para el sistema. El primero calcula la FC a través de la identificación del QRS, y envía las señales del ECG y FC al teléfono móvil. El segundo es una aplicación que permite adquirirlas y visualizarlas en la pantalla del móvil. Resultados: Se desarrolló un sistema electrónico portátil alimentado por una batería de 9 volts, de amplificación y ancho de banda que cumplen con los estándares internacionales, para monitoreo de ECG. La identificación del complejo QRS se realizó con el algoritmo de la segunda derivada, mientras que los programas realizados permiten enviar y recibir la información del ECG y la FC a través de BT, para visualizarlos en la pantalla del móvil. El monitoreo es factible hasta 15 m de distancia. Se probó en distintos móviles de Nokia®, Sony Ericsson® y Samsung®. Conclusiones: Este sistema muestra una alternativa de monitoreo móvil, con un teléfono por medio de BT y la programación en Java 2 Micro Edition (J2ME). Permite registrar el trazo del ECG y la FC, y puede implementarse en diferentes móviles

Heart Rate and Systolic Blood Pressure Variability on Recently Diagnosed Diabetics

Background: Diabetes affects approximately 250 million people in the world. Cardiovascular autonomic neuropathy is a common complication of diabetes that leads to severe postural hypotension, exercise intolerance, and increased incidence of silent myocardial infarction. Objective: To determine the variability of heart rate (HR) and systolic blood pressure (SBP) in recently diagnosed diabetic patients. Methods: The study included 30 patients with a diagnosis of type 2 diabetes of less than 2 years and 30 healthy controls. We used a Finapres® device to measure during five minutes beat-to-beat HR and blood pressure in three experimental conditions: supine position, standing position, and rhythmic breathing at 0.1 Hz. The results were analyzed in the time and frequency domains. Results: In the HR analysis, statistically significant differences were found in the time domain, specifically on short-term values such as standard deviation of NN intervals (SDNN), root mean square of successive differences (RMSSD), and number of pairs of successive NNs that differ by more than 50 ms (pNN50). In the BP analysis, there were no significant differences, but there was a sympathetic dominance in all three conditions. The baroreflex sensitivity (BRS) decreased in patients with early diabetes compared with healthy subjects during the standing maneuver. Conclusions: There is a decrease in HR variability in patients with early type 2 diabetes. No changes were observed in the BP analysis in the supine position, but there were changes in BRS with the standing maneuver, probably due to sympathetic hyperactivity

Correlation between Angiotensin Serum Levels and Very-Low-Frequency Spectral Power of Heart Rate Variability during Hemodialysis

Cardiovascular regulatory mechanisms that fail to compensate for ultrafiltration and cause hypovolemia during hemodialysis (HD) are not completely understood. This includes the interaction between the autonomic nervous system and the biochemistry that regulates blood pressure and modulates cardiac activity and vascular tone in response to hypovolemia in patients treated with HD. The objective was to evaluate the association of spectral indices of heart rate variability (HRV) with serum levels of angiotensin II, angiotensin 1–7, nitric oxide and total antioxidant capacity during HD. Electrocardiographic records were obtained from 20 patients during HD (3 h), from which HRV data and spectral power data in the very-low-frequency (VLF), low-frequency (LF) and high-frequency (HF) bands were generated. Three blood samples per patient were collected during HD (0.0, 1.5, 3.0 h) to determine the levels of biomarkers involved in the pressor response during HD. Angiotensin II had a positive correlation with VLF (r = 0.390) and with LF/HF (r = 0.359) and a negative correlation with LF (r = −0.262) and HF (r = −0.383). There were no significant correlations between HRV and the other biomarkers. These results suggest that during HD, VLF could reflect the serum levels of angiotensin II, which may be associated with the autonomic response to HD