Browsing by Author "Wong de balzan , Sara Null"

Now showing 1 - 13 of 13

An aide diagnosis system based on k-means for insulin resistance assessment in eldery people from the Ecuadorian highlands
(Institute of Electrical and Electronics Engineers Inc., 2018) Wong de balzan , Sara Null; Astudillo Salinas, Darwin Fabián; Encalada Torres, Lorena Esperanza; Severeyn, Erika
The lack of standardized cut-off values for the surrogate methods to diagnose Insulin resistance (IR) and the fact that the sensitivity of these methods have been studied in specific populations have limited their use in clinical routine. We developed a system that could aide to diagnosis IR in elderly people, analyzing four surrogate methods of IR estimation using a k-means clustering algorithm. Study subjects included 119 nondiabetic participants over 65 year old from Ecuadorian highlands. Blood tests included a two-point oral glucose test tolerance. The k-means clustering algorithm, was applied in one-dimensional experiments for the Homa-IR, Quicki, Avignon and Matsuda. The population was divided into three clusters: C N with normal values, C IR with IR and C a with values in between. The number of individuals classified in each C Ir was very different according to each method. With the cut-off values obtained, for each method, the system for the evaluation of IR in elderly people was developed. Our work is intended to aid physicians in the early detection of IR by using information from diverse methods.
Assessing the SNR influence in the estimation of the mean frequency of lower limbs sEMG signals
(2018) Rojas Bustos, Andrés Bolívar; Mora Tola, Esteban Javier; Minchala Ávila, Luis Ismael; Wong de balzan , Sara Null; Farfán Bernal, Ángel Bolívar
The mean frequency of the power spectrum (MNF) is commonly used to describe the frequency content of an electromyographic (EMG) signal. The objective of this study is to determine the minimum/desirable signal to noise ratio (SNR) value to achieve a reliable measurement of the MNF in superficial EMG (sEMG) signals of lower limbs during gait. To this end, measurements of MNF and SNR were taken in nine muscles of 21 subjects, and recorded signals were contaminated with different noise levels. The minimum threshold of a desirable SNR was determined using the K-means algorithm. A lower bound of 5.51 dB was determined as the SNR value for sEMG acquisition, while 12.28 dB is the desirable SNR value for recording sEMG signals. The methodology presented throughout this paper helps in the determination of the minimum SNR value necessary to validate the sEMG acquisition process that can be used, for example, as a control signal for identifying motion intention in the development of control systems devoted for a lower limb exoskeleton.
Cardiac autonomic modulation in response to a glucose stimulus
(2019) Perpiñan, Gilberto; Severeyn, Erika; Wong de balzan , Sara Null; Altuve, Miguel
This paper focuses on the effect of a sudden increase of plasma glucose concentration in the cardiac autonomic modulation using time-domain and frequency-domain heart rate variability (HRV) measures. Plasma glucose and insulin levels, measured each 30 min during an oral glucose tolerance test, and RR ¯ $overline { ext {RR}}$ (mean of the RR interval), SDNN (standard deviation of normal-to-normal heartbeats), rMSSD (root-mean-square of successive differences between normal heartbeats), TP (total spectral power), LF and HF (power of the low- and high-frequency bands), LF norm and HF norm (LF and HF in normalized units), and LF/HF ratio of the HRV signal, obtained from 5-min-long ECG recordings during each phase of the test, were analyzed for subjects with the metabolic syndrome, marathon runners, and a control group. Results show that, after the glucose load, subjects with the metabolic syndrome experienced an increased sympathetic and decreased parasympathetic tone, which suggests an imbalance in cardiac autonomic modulation as a consequence of hyperglycemia and hyperinsulinemia. The significance of this study lies in the use of the ECG to assess the effects of a sudden increase in plasma glucose concentration on the cardiac autonomic modulation in subjects with different cardiovascular and metabolic conditions. Graphical Abstract Time-domain and frequency-domain heart rate variability measures are altered in subjects with different cardiovascular and metabolic conditions during an oral glucose tolerance test
Confiabilidad del cuestionario internacional de actividad física en adultos mayores de la sierra ecuatoriana
(2020) Encalada Torres, Lorena Esperanza; Aucapiña Camas, Noemi Maricela; Avila Andrade, Marcela Estefania; Buri, Ivanna; Wong de balzan , Sara Null
Introduccion: La actividad fisica puede influenciar positivamente sobre la calidad de vida de adultos mayores, mejorando su funcionalidad y previniendo la discapacidad; de ahi la importancia de buscar una herramienta que permita evaluar la actividad fisica en personas mayores de 65 anos.Objetivo: Establecer la confiabilidad del cuestionario Internacional de Actividad Fisica version corta, en una poblacion adulta mayor de 65 anos de la sierra ecuatoriana.Material y metodos: Se determinaron los niveles de actividad fisica alto, moderado y bajo en 387 adultos mayores usando el cuestionario Internacional de Actividad Fisica version corta (IPAQ-C). Fueron incluidos adultos mayores de 65 anos de ambos sexos. El cuestionario se aplico en dos ocasiones con un lapso de 1 a 2 semanas (IPAQ1 e IPAQ2). Se utilizo el coeficiente de correlacion intraclase para la fiabilidad intraobservador, el alfa de Cronbach para la consistencia interna. Los resultados fueron analizados en SPSS.Resultados: El mayor numero de adultos mayores participantes estuvieron entre los 65 a 74 anos (64,6%) y en su mayoria mujeres (63,6%). El grupo etario entre 65 a 74 anos, fue el grupo que presento mayor nivel de actividad fisica alta. Con el aumento de la edad el nivel de actividad fisica alta disminuyo (p < 0,001). Los valores del Alfa de Cronbach para el IPAQ1 e IPAQ2 fueron 0,685 y 0,701 respectivamente. La confiabilidad intra-observador total fue de 0,866.Conclusiones: Los resultados muestran niveles elevados de actividad fisica. Los valores hallados para medir la confiabilidad y la consistencia interna permiten concluir que el IPA-C es adecuado para la evaluacion del nivel de actividad fisica de la poblacion adulta mayor de la sierra ecuatoriana.
Hypertension in older adults in the urban area of Cuenca
(2018) Encalada Torres, Lorena Esperanza; Alvarez Tapia, Karen Adriana; Barbecho Barbecho, Paul Andres; Wong de balzan , Sara Null
Introduction: The population of older adults has increased, and with it chronic non communicable diseases such as hypertension, considered a public health problem. Objective: To determine the frequency of hypertension in older adults of urban parishes in the city of Cuenca. Methodology: A descriptive study was carried out in 378 older adults. It was considered hypertensive after two blood pressure measurements taken at least one week apart, in which the systolic blood pressure was greater than or equal to 140 mmHg and diastolic blood pressure greater than or equal to 90 mmHg. Hypertensive people were characterized according to sociodemographic parameters, family history, nutritional status and physical activity. For the sampling, census areas of each parish were used, with simple random sampling. The data were analyzed and processed in the SPSS program version 15.0, using frequency distribution, measures of central tendency: Mean and dispersion measures: Standard deviation. Results: The frequency of hypertensive was 52.5%, 65.1% of hypertensive patients were women and 34.9% were men. 57.6% of hypertensive patients were between 65 and 74 years of age. 41.2% had complete primary education. 76.4% did not have an occupation with salary remuneration. 51.2% had no family history of hypertension. 40% performed physical activity moderately and 41.9% presented obesity. Conclusion: The frequency of hypertension in urban older adults exceeds the global figures established for this age group. © 2018 Revista Latinoamericana de Hipertension. All rights reserved.
Lower limbs motion intention detection by using pattern recognition
(Institute of Electrical and Electronics Engineers Inc., 2018) Astudillo Palomeque, Felipe Emmanuel; Charry Ramírez, José Ricardo; Minchala Ávila, Luis Ismael; Wong de balzan , Sara Null
Electromyographic (EMG) signals processing allows to perform the detection of the intention of movement of the limbs of the human body in order to further use this decision to control wearable devices. For instance, robotic exoskeletons main objective consist of a human-robot interface capable of understanding the user’s intention and reacting appropriately to provide the required assistance in an opportune way. In this paper, we study the performance of superficial EMG intended to design a intent pattern recognition based on Artificial Neural Networks (ANN) trained by the Levenberg-Marquardt method. Experiments consisting in 231 EMG records corresponding to 13 lower limbs muscles from 21 healthy subjects were considered. The EMG signals were randomly divided into the following sets: 70 % for training, 15 % for validation and 15 % for evaluation. The ANN-based pattern recognition was evaluated sample per sample with the movement intention annotations (target) and after the traininig operation end, the performance was evaluated in relation to the events (number of steps). The results show an accuracy of 90,96% sample per sample and 94,88% for an based on events evaluation. These findings motivates the use of this methodology for the classification of the motion intention detection in subjects with pathologies in the lower limbs.
Mean frequency and noise from patients with pathologies in lower limbs
(Institute of Electrical and Electronics Engineers Inc., 2020) Minchala Ávila, Luis Ismael; Mora Tola, Esteban Javier; Wong de balzan , Sara Null; Astudillo Salinas, Darwin Fabián; Vázquez Rodas, Andrés Marcelo; Cárdenas León, Verónica Vanessa; Ayavaca Tapia, Luz María
Raw electromyography (EMG) signals are useful for several purposes in the analysis of muscles in both clinical and engineering applications. For instance, muscles fatigue is, typically, assessed by the mean frequency (MNF) of the EMG signal. Previous research works have shown that there is a positive correlation between the signal to noise ratio (SNR) of the EMG signal and its MNF value. The aim of this work is to determine and compare MNF in subjects with impairments in the lower limbs. Measurements of the MNF and the SNR were performed in nine muscles of six pathologic subjects, which were compared with a similar database of subjects without apparent pathologies. The MNF value was estimated using the power spectral density. The SNR for pathologic patients database was higher (17.28±1.67 dB) with respect to the database of subjects without apparent pathologies (12.86±1.71 dB). Subjects with pathologies in the lower limbs presented a decrease in the average value of the MNF.
Random sub-sampling cross validation for empirical correlation between heart rate variability, biochemical and anthropometrics parameters
(Springer Verlag, 2019) Severyn, Erika; Velásquez Fernández, Jesús María; Herrera, Héctor Antonio; Wong de balzan , Sara Null
According to National Cholesterol Education Program-Adult Treatment Panel III, metabolic syndrome (MS) is a condition characterized by: Dyslipidemia, abdominal obesity, high levels in fasting glucose and arterial hypertension. Studies have explored indexes using dimensional analysis (DA) formed by anthropometric, biochemical and heart rate variability parameters for the diagnosis of MS. The dimensionless numbers made from DA have the capability to manage them as a mathematical functionality; therefore it is possible to relate them, even when the parameters used are not connected. The aim of this work is to find a polynomial equation using as variables two dimensionless numbers designed from anthropometrical and biochemical (π_IS) parameters and from heart rate variability (π_HRV) parameters. A fitting using a parametrical random sub-sampling cross validation (RSV) was performed using as an objective function the least squares method. A database of 40 subjects (25 control subjects and 15 subjects with MS) was employed. The polynomial parameters that best fit the database used correspond to a polynomial of order eight. The RSV substantially improves the adjustment of the polynomial compared to the application of the least squares method only (0.6678 vs. 0.3255). The polynomial relationship between π_IS and π_HRV allows the possibility to determine biochemical and anthropometric variables from heart rate variability parameters. Due to the limited number of subjects in the database used, it is necessary to repeat this methodology in a more extensive database to determine a more general polynomial that can be used with any type of population.
RR stress test time series classification using neural networks
(Institute of Electrical and Electronics Engineers Inc., 2018) Jaramillo Ayavaca, Wilson Xavier; Astudillo Salinas, Darwin Fabián; Solano Quinde, Lizandro Damián; Palacio Baus, Kenneth Samuel; Wong de balzan , Sara Null; Solano Quinde, Lizandro Damián
The RR time series, obtained from the R waves of the ECG, are a representation of the heart rate. This work presents the use of an artificial neural network (ANN) to classify RR time series from an ECG stress test. Four classes of RR time series were defined very good, good, low quality and useless. We use a preprocessing stage to split input data vectors into N W data windows for which we compute the standard deviation of the RR interval (SD RR ) to generate the input features vector of a multilayer perceptron network architecture. We introduce a saturation value S in order to limit SD RR values. 520 RR time series from 65 records of ECG stress test were analyzed. Experiments were performed to explore the influence of parameters S and N W . 40 subjects records are used in training and the remaining for testing. The classification results show a matching correlation ratio above 71%, which is higher than the …
Síndrome metabólico y actividad física en adultos mayores de la sierra ecuatoriana
(2017) Wong de balzan , Sara Null
Objective Determine the prevalence of the metabolic syndrome, the level of physical activity and the association with these factors in the elderly from the Ecuadorian highlands. Methods Cross-sectional study that evaluated 387 older adults from Cuenca-Ecuador, who wished to participate and signed the informed consent. The diagnosis of metabolic syndrome was made using the criteria of the National Program of Education on Cholesterol and the Adult Treatment Panel III, for the value of Abdominal Circumference the criteria used for the Asian population was considered. The level of physical activity was evaluated by the short version of the International Physical Activity Questionnaire. The groups with and without metabolic syndrome were compared using the chi-square test and student’s t-test. The analysis of variance was used to evaluate the association between the components of the metabolic syndrome and the level of physical activity. Results The prevalence of metabolic syndrome was high (59.9 %), as well as the high level of physical activity (45 %), however, there was no significant association between the metabolic syndrome and physical activity level. Conclusions Older adults diagnosed with metabolic syndrome presented the same level of physical activity as individuals without this diagnosis. It is necessary to confirm the present findings using direct measurement instruments of physical activity
Single-channel electromyography based on Arduino for analysis of the swing phase in normal gait
(Instituto de Ingenieros Eléctricos y Electrónicos Inc., 2018) Rojas Bustos, Andrés Bolívar; Avendaño Farfan, Angel; Ayavaca Tapia, Luz María; Cárdenas, Verónica Judith; Urbay Mora, Esteban; Wong de balzan , Sara Null; Minchala Ávila, Luis Ismael; Ayavaca Tapia, Luz María
This paper presents a thorough evaluation of a single-channel electromyography (EMG) signal acquisition board based on Arduino technology to characterize the swing phase of normal gait. A total register of 231 EMG signals corresponding to 11 lower limb muscles (7 right and 4 left) of 21 subjects was generated. For each record, the subject made a coordinated paused walk based on a sequence of audible tones to indicate each step. The maximum amplitude (MA) defined as the maximum value of the amplitude of the rectified and smoothed EMG signal corresponding to each of the swing sub-phases (initial, mid and terminal) were compared for the left and right limbs. The MA between swing sub-phases were also examined. Results show that the amplitudes obtained in each swing sub-phase of the gait records are coherent with the normal swing phase. These findings allow to recommend the use of the EMG acquisition prototype for studies addressed to the detection of motion intention
Socioeconomic status and nutritional status as predictors of food insecurity in older adults: a case study from southern Ecuador
(2022) Bedoya Ortega, Maria Elisa; Wong de balzan , Sara Null; Alvarado Romero, Samantha Natali; Encalada Torres, Lorena Esperanza; Encalada Torres, Janneth Olivia; Abril Ulloa, Sandra Victoria
While life expectancy is increasing due to scientific advancement, quality of life in aging depends, among other factors, on the nutritional status and socioeconomic status of older adults. To determine socioeconomic status and its association with nutritional status as a predictor of food insecurity among older adults in southern Ecuador, a cross-sectional study of 188 older adults in urban areas and 212 in rural areas was conducted. Nutritional status, food insecurity, and socioeconomic status were measured. Data were analyzed using SPSS v 15.0 for descriptive statistics and bivariate analysis. Of the older participants, 59% had malnutrition, the majority women, and 24.7% were in poverty. Underweight was associated with low socioeconomic status for adults between 65 and 74 years old (OR = 7.710; CI 95% = 1.691–35.147), while obesity was associated with low socioeconomic status and non-manual labor (OR = 3.048; CI 95% = 1.268–7.326). Over 80% of older adults living in homes without children younger than 18 and at low socioeconomic status had food insecurity. The prevalence of underweight, overweight, and obesity points to widespread nutritional problems, especially in rural areas, that are significantly associated with low socioeconomic status. This demonstrates the need for multidisciplinary programs and government policies that can contribute to reducing food insecurity among the highly vulnerable older population.
Towards the insulin resistance and obesity diagnosis: A dimensional analysis approach
(Institute of Electrical and Electronics Engineers Inc., 2018) Velásquez, Jesús; Severeyn, Erika; Herrera, Hector Antonio; Utrera, Nestor; Encalada Torres, Lorena Esperanza; Wong de balzan , Sara Null; Velásquez, Jesús
Diabetes mellitus and cardiovascular diseases are ailments related to insulin resistance (IR) and obesity. The existing methods for IR and obesity diagnosis are the HOMA-IR and body mass index (BMI), respectively. Those methods have limitations in the diagnosis. The aim of this research is to propose dimensionless indexes that can diagnose subjects with IR and obesity using anthropometrics and biochemical variables (waist circumference, height, weight, systolic blood pressure, diastolic blood pressure and triglycerides). Three dimensionless indexes, designed from the π Vaschy-Buckingham theorem, were assessed using receiver operating characteristic (ROC) curves and a database of 829 subjects. The index π 1 , constructed with the variables: waist circumference, triglycerides height and weight; obtained a better performance as classifier of IR and obesity, presenting an area under the ROC curve of 0.78, sensitivity of 0.82 and specificity of 0.68 for IR diagnosis, and an area under the ROC curve of 0.68, sensitivity of 0.66 and specificity of 0.65 for obesity diagnosis. The π 1 dimensionless index designed in this study is a simple method that allows diagnosing two pathologies from variables that can be collected in a routine medical examination.