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Some patient groups (for example, paraplegics) have an impaired bladder volume sensation, often associated with the inability to urinate properly. A common therapy is regular intermittent self-catheterisation following a fixed time schedule. To reduce the risk of complications and to enhance quality of life, a demanddriven emptying scheme would be preferable for some patients. To achieve this, a promising concept is non-invasive continuous impedance-based volume monitoring to estimate the appropriate moment for catheterisation.Based on the technology of Electrical Impedance Tomography, this work investigates how this can be used for reliable bladder volume estimation. The work emphasises on appropriate electrode positions and estimation algorithms. Further, device concepts are shown and disturbances and movement artefacts are analysed. Finally, the concept is evaluated in FEM-simulation, in vitro-measurements as well as clinical trials. Subsuming, bladder volume estimation based on Electrical Impedance Tomography shows good linearity, but has potential to be improved with regard to repetition accuracy and movement artefact suppression in future research.

Myocardial electrical impedance is influenced by the mechanical activity of the heart. Therefore, the ischemia-induced mechanical dysfunction may cause specific changes in the systolic-diastolic pattern of myocardial impedance, but this is not known. This study aimed to analyze the phasic changes of myocardial resistivity in normal and ischemic conditions. Myocardial resistivity was measured continuously during the cardiac cycle using 26 different simultaneous excitation frequencies (1 kHz–1 MHz) in 7 anesthetized open-chest pigs. Animals were submitted to 30 min regional ischemia by acute left anterior descending coronary artery occlusion. The electrocardiogram, left ventricular (LV) pressure, LV dP/d t, and aortic blood flow were recorded simultaneously. Baseline myocardial resistivity depicted a phasic pattern during the cardiac cycle with higher values at the preejection period (4.19 ± 1.09% increase above the mean, P < 0.001) and lower values during relaxation phase (5.01 ± 0.85% below the mean, P < 0.001). Acute coronary occlusion induced two effects on the phasic resistivity curve: 1) a prompt (5 min ischemia) holosystolic resistivity rise leading to a bell-shaped waveform and to a reduction of the area under the LV pressure-impedance curve (1,427 ± 335 vs. 757 ± 266 Ω·cm·mmHg, P < 0.01, 41 kHz) and 2) a subsequent (5–10 min ischemia) progressive mean resistivity rise (325 ± 23 vs. 438 ± 37 Ω·cm at 30 min, P < 0.01, 1 kHz). The structural and mechanical myocardial dysfunction induced by acute coronary occlusion can be recognized by specific changes in the systolic-diastolic myocardial resistivity curve. Therefore these changes may become a new indicator (surrogate) of evolving acute myocardial ischemia.

Introduction: the body composition and lifestyle of university students are influenced by behavioral, psychological, socioeconomic and cultural factors. Objective: to analyze body composition and its correlation with lifestyle in a sample of university students in the health area living at the Ribeirao Preto Campus of the University of São Paulo (USP). Methodology: a cross-sectional study was conducted on 501 students enrolled in USP courses of the Ribeirao Preto Campus. Weight and height were measured and body composition was determined by bioelectrical impedance. The short version of the International Physical Activity Questionnaire (IPAQ) was then applied. Results: The sample predominantly consisted of females (73.05%), with 26.95% males. The averages of age, weight, stature body mass index (BMI), total fat mass and fat-free mass were 20.4 ± 2.8 years, 63.0 ± 13.5 kg, 166.9 ± 9.0 cm, 22.4 ± 3.4 kg/m², 24.0 ± 7.5%, 45.3 ± 10.3 kg, respectively. Although almost 70% of the students were in the normal BMI range, 70.8% of them had high levels of fat mass. According to IPAQ, the individuals were classified as sedentary (10.2%), irregularly active (39.3%), active (42.1%), and very active (8.4%). Conclusions: Most of the university students studied were classified as being of normal weight according to the BMI, but the high levels of body fat mass detected should not be overlooked. In addition, even though most of the sample was considered to be active, according to the IPAQ, it can be seen that practically half the students (49.5%) were irregularly active or sedentary. Introducción: la composición corporal y el estilo de vida de los estudiantes universitarios se ven influidos por factores conductuales, psicológicos, socioeconómicos y culturales. Objetivo: analizar la composición corporal y su correlación con el estilo de vida en una muestra de estudiantes universitarios del área de la salud que viven en el campus de Ribeirao Preto de la Universidad de São Paulo (USP). Metodología: estudio transversal que se llevó a cabo en 501 estudiantes matriculados en los cursos del Campus USP Ribeirão Preto. El peso y la talla se midieron y la composición corporal se determinó mediante impedancia bioeléctrica. A continuación, se aplicó la versión corta de la International Physical Activity Questionnaire (IPAQ). Resultados: La muestra consistió predominantemente de mujeres (73,05 %), con 26,95 % de hombres. Los promedios de edad, peso, índice de masa corporal (IMC), la masa grasa total y la masa libre de grasa fueron 20,4 ± 2,8 años, 63,0 ± 13,5 kg, 166,9 ± 9,0 cm, 22,4 ± 3,4 kg/m², 24,0 ± 7,5%, 45,3 ± 10,3 kg, respectivamente. Aunque cerca del 70% de los estudiantes estaban en el rango normal de IMC, 70,8% tenían altos niveles de masa grasa. Según IPAQ, los individuos fueron clasificados como sedentarios (10,2%), irregularmente activos (39,3%), activos (42,1%), y muy activos (8,4%). Conclusiones: La mayoría de los estudiantes universitarios estudiados fueron clasificados como de peso normal de acuerdo con el índice de masa corporal, pero los altos niveles de masa grasa corporal detectada no deben pasarse por alto. Además, a pesar de que la mayor parte de la muestra se considera activo, de acuerdo con la IPAQ, se puede ver que prácticamente la mitad de los estudiantes (49,5%) eran de forma irregular activos o sedentarios.

Electrical bioimpedance was used to detect local volume and aggregation changes in blood. This was done with two separate experimentation processes to improve upon current research methods. Abdominal internal hemorrhaging is bleeding and pooling of blood within the abdominal cavity which can put the welfare of the patient at risk and may cause organ failure. Electrical bioimpedance is the response of biological tissue to applied electrical current. In cooperation with Bioparhom, electrical bioimpedance was used as a detection device for abdominal internal hemorrhaging. It is hypothesized that electrical bioimpedance could be a non-invasive and cost effective avenue for the detection of internal bleeding. In this study we investigate the use of electrical bioimpedance with a custom 8x8 needle electrode array, for detecting and locating the blood pooling due to a drop in resistivity in a rat using a Z-Metrix (function generator by Bioparhom). 5 and 95 kHz signals were inputted into a dead rat experiencing internal bleeding of porcine blood at a rate of 3.33 ml/min to 10 ml. For 8 rats, the 5 kHz frequency was found to be more sensitive to internal blood pooling. Red blood cell aggregation is a physiological process where red blood cells form reversible aggregates. RBC aggregation is an important indicator for physicians for the health of the circulatory system. Utilizing electrical bioimpedance, it is hypothesized that a reactance change as a result of blood aggregation will be detected. As well, a method is developed using impedance spectroscopy to determine s frequency which exhibits the highest reactance change during blood aggregation. This sensitive frequency, found to be 304 kHz, is compared to a frequency used by previous studies (100 kHz) to validate its. Using the Z-Metrix (function generator by Bioparhom) with a custom 4 electrode configuration, 2 ml of porcine blood mixed with 2 mg/ml of EDTA is tested for 2 minutes at a single frequency. The 304 kHz is found to be the most sensitive of the frequencies tested to reactance changes during aggregation. Results found for blood samples give an average AIc of 27.32 ± 11.44, which is within the physiological range for porcine blood of 3-30. It is seen that the 304 kHz has a higher precision than the 100 kHz frequency, but the AIc is within the same magnitude. As a result, 304 kHz is found to be a more favorable frequency than the previously published 100 kHz for the trials performed based on precision of the results and the sensitivity of the reactance change to blood aggregation.

We present a novel method for localization of large blood vessels using a bioimpedance based needle positioning system on an array of ten monopolar needle electrodes. The purpose of the study is to develop a portable, low cost tool for rapid vascular access for cooling and controlled reperfusion of cardiac arrest patients. Preliminary results show that localization of blood vessels is feasible with this method, but larger studies are necessary to improve the technology.

Submitted by Boris Flegr (boris@uerj.br) on 2021-01-06T20:57:53Z No. of bitstreams: 1 DISSERTACAO FINAL Viviane_Abrantes_Jardim.pdf: 680471 bytes, checksum: 2119e877d4a7a73124e8f22609126773 (MD5) Made available in DSpace on 2021-01-06T20:57:53Z (GMT). No. of bitstreams: 1 DISSERTACAO FINAL Viviane_Abrantes_Jardim.pdf: 680471 bytes, checksum: 2119e877d4a7a73124e8f22609126773 (MD5) Previous issue date: 2013-03-25 Inflammatory Bowel Disease (IBD) is a disorder characterized by diffuse inflammation of the gastrointestinal tract. The two main types of IBD are ulcerative colitis (UC) and Crohn's disease (CD), both coursing with changes in nutritional status (NS). The objective of this study was to investigate the existence of associations between body composition measured by electrical bioimpedance (BIA) and by the equations used for the estimate of fat percent in patients with CD and UC on ambulatory treatment and when compared to healthy individuals. A cross-sectional study was conducted on 101 patients with IBD, 50 of them with CD (GCD) and 51 with UC (GUC), and on 35 healthy subjects (GCON), selected at the Ambulatory of Pedro Ernesto University Hospital (HUPE) of the Rio de Janeiro State University (UERJ). Sociodemographic information such as practice of physical activity, smoking habit, previous diseases and surgical procedures was collected. Anthropometric evaluation consisted of weight; height; arm, waist and hip circumferences; arm muscle circumference (AMC), and the following skin folds: triceps, biceps, pectoral, axillary, subscapular, suprailiac, supraspinal, abdominal, leg, and thigh. Percent body fat (%BF) was estimated using equations based on the sum of skin folds and by BIA. Percent subcutaneous fat was estimated as the sum of ten folds. The laboratory variables analyzed, included: complete blood count, total protein, albumin, globulin, erythrocyte sedimentation rate, and C-reactive protein. Data were analyzed statistically using the STATA software, version 10.0. Classification of NS based on body mass index (BMI) revealed a low prevalence of malnutrition in the groups evaluated. Direct analysis of weight and BMI measurements revealed that patients with CD had significantly lower values than GCON individuals. The evaluation of AMC showed that GCD and GUC patients had depleted lean mass compared to GCON individuals, with no difference between the two groups of patients with IBD. No differences in %BF determined by BIA were detected among the three study groups. When %BF was determined using the formulas of Peterson, Durnin & Womersley and Jackson & Pollock (which use the sum of three folds), patients with CD were found to have significantly depleted adipose tissue compared to GCON and GUC individuals. Comparison of %BF values obtained by different estimate methods showed that the equations of Jackson & Pollock (which use the sum of three and seven folds) yielded significantly lower results than the equations of Peterson and Durnin & Womersley for the two patient groups. Seric levels of total protein and albumin, as well as red blood cell count and relative count of lymphocytes were lower in the individuals with CD than the individuals of the control group and/or the patients with UC. Patients with CD showed significant involvement of NS compared to patients with UC and especially compared to healthy individuals. A Doença Inflamatória Intestinal (DII) é uma desordem caracterizada pela inflamação difusa do trato gastrointestinal. Os dois principais tipos de DII são a Retocolite Ulcerativa (RCU) e a Doença de Crohn (DC) e ambas cursam com alterações no estado nutricional (EN). O objetivo deste estudo foi comparar a composição corporal, obtida por meio de diferentes métodos, em pacientes com DC e RCU em atendimento ambulatorial, avaliando possíveis diferenças nos grupos de doentes entre si e quando comparados a indivíduos saudáveis. Foi realizado um estudo transversal incluindo 101 pacientes com DII, sendo 50 com DC (GDC) e 51 com RCU (GRCU), além de 35 indivíduos saudáveis (GCON), selecionados no Ambulatório do Hospital Universitário Pedro Ernesto (HUPE) da Universidade do Estado do Rio de Janeiro (UERJ). Informações sócio-demográficas e pessoais, como prática de exercício físico, tabagismo, doenças pregressas e procedimentos cirúrgicos prévios foram coletadas. A avaliação antropométrica consistiu de: peso; altura; circunferências do braço, da cintura e do quadril; circunferência muscular do braço (CMB) e pregas cutâneas do tríceps, bíceps, peitoral, axilar, subescapular, suprailíaca, supraespinhal, abdominal, perna e coxa. O percentual de gordura corporal (% GC) foi estimado a partir de equações que utilizam o somatório de pregas cutâneas e por meio de bioimpedância elétrica (BIA). Para estimar o percentual de gordura subcutânea foi utilizado o somatório de dez dobras. As variáveis laboratoriais analisadas foram: hemograma completo, proteínas totais, albumina, globulina, velocidade de hemossedimentação e proteína C reativa. As análises estatísticas foram realizadas utilizando-se o software STATA versão 10.0. A classificação do EN, por meio do índice de massa corporal (IMC), evidenciou baixa prevalência de desnutrição nos três grupos avaliados. Ao analisar diretamente as medidas antropométricas de peso e IMC, observou-se que os pacientes com DC apresentaram valores significativamente menores do que os indivíduos do grupo controle. A avaliação da CMB mostrou que os pacientes do GDC e GRCU apresentaram depleção de massa magra em comparação aos indivíduos do GCON, porém sem apresentar diferenças entre os dois grupos de pacientes com DII. Em relação ao %GC obtido por BIA não foram verificadas diferenças entre os três grupos de estudo. Ao se verificar o %GC com a utilização das fórmulas de Peterson, Durnin & Womersley e Jackson & Pollock (que utiliza o somatório de três dobras) observou-se que os pacientes com DC apresentaram tecido adiposo significativamente depletado em relação aos indivíduos do GCON e do GRCU. Ao compararmos os %GC obtidos por diferentes métodos de estimativa, observou-se que as equações de Jackson & Pollock (que utilizam o somatório de três e sete dobras) apresentaram resultados significativamente menores quando comparados aos das equações de Peterson e Durnin & Womersley, nos dois grupos de pacientes. Os níveis séricos de proteínas totais e albumina, e a contagem total de hemácias foram menores nos indivíduos com DC quando comparados aos indivíduos do grupo controle e/ou aos indivíduos do grupo com RCU. Os pacientes com DC apresentaram comprometimento importante do EN em comparação aos pacientes com RCU e, notadamente, em relação aos indivíduos saudáveis.

Background: This study analyzed the phase-angle (PA) values of hospitalized HVI-infected patients by comparing them with those reported for a healthy population and investigated their relation with nutritional parameters. Methods: This is a cross-sectional study including 101 hospitalized patients diagnosed with HIV infection and evaluated by bioimpedance, anthropometry and biochemical tests. The phase angle values, weight loss percentage (%WL), body mass index (BMI), arm muscle circumference (AMC), tricipital skinfold (TSF), body fat percentage (%BF) and albumin were considered. In order to compare with values for the healthy population, the PA z-score of the patients under study was calculated. Spearman's correlation and the multiple linear regression model were used to identify nutritional parameters associated with the PA z-score. Results: The patients showed a mean PA z-score of -2.6 ± 1.5, and only 6.6% of them with a positive value. The PA z-score values correlated with %WL (r = -0.51; p < 0.0001), albumin (r = 0.49; p < 0.0001), BMI (r = 0.58; p < 0.0001), AMC (r = 0.41; p < 0.0001), TSF (r = 0.47; p < 0.001) and %BF (r = 0.48, p < 0.0001). In multiple analysis %WL (p = 0.008), albumin (p = 0.01), AMC (p < 0.0001) and %BF (p = 0.0003) remained associated with the score. Conclusions: Low PA z-score values were observed, suggesting a worse clinical prognosis for the patients. The inclusion of the PA z-score as a nutritional indicator during care provision to HIV-infected patients is recommended. Antecedentes: Este estudio analizaba los valores del ángulo de fase (AF) de pacientes hospitalizados e infectados por el VIH al compararlos con los notificados para un población sana e investigaba su relación con los parámetros nutricionales. Métodos: Se trataba de un estudio transversal que incluyó a 101 pacientes hospitalizados diagnosticados de infección por el VIH y en los que se evaluó la bioimpedancia, la antropometría y parámetros bioquímicos. Se consideraron los valores del ángulo de fase, el porcentaje de pérdida de peso (%PP), el índice de masa corporal (IMC), la circunferencia muscular del brazo (CMB), el pliegue tricipital (PT), el porcentaje de grasa corporal (%GC) y la albúmina. Para compararlos con los de una población sana, se calcularon las puntuaciones z del AF de los pacientes estudiados. Se emplearon la correlación de Spearman y el modelo de regresión linear múltiple para identificar los parámetros nutricionales asociados con la puntuación z del AF. Resultados: Los pacientes mostraron una puntuación z del AF de -2,6 ± 1,5, el 23,7% de ellos tenían un valor superior a -1,65 y sólo el 6,6% un valor positivo. Los valores de las puntuaciones z del AF se correlacionaron con el %PP (r = -0,51; p < 0,0001), la albúmina (r = 0,49; p < 0,0001), el IMC (r = 0,58; p < 0,0001), la CMB (r = 0,41; p < 0,0001), el PT (r = 0,47; p < 0,001) y el %GC (r = 0,48, p < 0,0001). En el análisis múltiple, el %PP (p = 0,008), la albúmina (p = 0,01), la CMB (p < 0,0001) y el %GC (p = 0,0003) seguían asociándose con la puntuación z. Conclusiones: Obtuvimos unos valores bajos de puntuación z del AF, lo que sugiere un peor pronóstico clínico en los pacientes. Recomendamos la inclusión de la puntuación z del AF como un indicador nutricional durante la provisión de la atención sanitaria a los pacientes infectados por el VIH.

Made available in DSpace on 2013-08-12T19:10:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-05-01 Made available in DSpace on 2013-09-30T18:35:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-05-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:48:09Z No. of bitstreams: 0 Made available in DSpace on 2014-05-20T13:48:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-05-01 Background: This study analyzed the phase-angle (PA) values of hospitalized HVI-infected patients by comparing them with those reported for a healthy population and investigated their relation with nutritional parameters.Methods: This is a cross-sectional study including 101 hospitalized patients diagnosed with HIV infection and evaluated by bioimpedance, anthropometry and biochemical tests. The phase angle values, weight loss percentage (%WL), body mass index (BMI), arm muscle circumference (AMC), tricipital skinfold (TSF), body fat percentage (%BF) and albumin were considered. In order to compare with values for the healthy population, the PA z-score of the patients under study was calculated. Spearman's correlation and the multiple linear regression model were used to identify nutritional parameters associated with the PA z-score.Results: The patients showed a mean PA z-score of -2.6 +/- 1.5, and only 6.6% of them with a positive value. The PA z-score values correlated with %WL (r = -0.51; p < 0.0001), albumin (r = 0.49; p < 0.0001), BMI (r = 0.58; p < 0.0001), AMC (r = 0.41; p < 0.0001), TSF (r = 0.47; p < 0.001) and %BF (r = 0.48, p < 0.0001). In multiple analysis %WL (p = 0.008), albumin (p = 0.01), AMC (p < 0.0001) and %BF (p = 0.0003) remained associated with the score.Conclusions: Low PA z-score values were observed, suggesting a worse clinical prognosis for the patients. The inclusion of the PA z-score as a nutritional indicator during care provision to HIV-infected patients is recommended. (Nutr Hosp. 2012;27:771-774) DOI:10.3305/nh.2012.27.3.5684 São Paulo State Univ, Botucatu Sch Med, UNESP, São Paulo, Brazil São Paulo State Univ, Inst Biosci, UNESP, São Paulo, Brazil São Paulo State Univ, Botucatu Sch Med, UNESP, São Paulo, Brazil São Paulo State Univ, Inst Biosci, UNESP, São Paulo, Brazil

[ANGLÈS] Electrical Bioimpedance (EBI) through transthoracic measurements offers a non-invasive manner to measure hemodynamic values. In the last decades, advances in the field of electrodes, electronic hardware and the development of textrodes have paved the ways for smaller, easier to use equipment for EBI measurements. In this thesis a AD5933-based board originally designed for full-body edema monitoring has been adapted to perform continuous transthoracic EBI measurements. For this objective 2 pieces of software have been developed: a firmware in C to control the board and a user interface in Visual Basic 2008 for Windows to easily monitor and record captured data. This thesis also presents the results of the validation tests carried out onto 2 test subjects. These results have been exported and analysed with MATLAB and show the feasibility of using this system for extended monitoring but no conclusive data can be extracted without a further analysis. [CASTELLÀ] La bioimpedancia eléctrica (EBI) mediante medidas transtorácicas ofrece una manera no invasiva de medir valores hemodinámicos. En las últimas décadas, avances en el campo de los electrodos, hardware electrónico y en el desarrollo de electrodos textiles han abierto camino a poder crear equipo más pequeño y fácil de usar para las medidas de bioimpedancia eléctrica. En esta tesis se ha adaptado una placa basada en un chip AD5933 diseñada originariamente para realizar la monitorización de cuerpo entero de edemas. Para este objetivo se han desarrollado dos piezas de software: un firmware en C para controlar la placa y una interfaz de usuario en Visual Basic 2008 para Windows para monitorizar y grabar fácilmente los datos medidos. Esta tesis también presenta los resultados de tests de validación llevados a cabo en dos individuos. Estos resultados han sido exportados y analizados con MATLAB para mostrar la factibilidad de usar este sistema para monitorizaciones de larga duración pero no es posible sacar ningún dato concluyente sin realizar más análisis a los datos. [CATALÀ] La bioimpedància elèctrica (EBI) mitjançant mesures transtoràcies ofereix una forma no invasiva de mesurar valors hemodinàmics. En les darreres dècades avanços en el camp dels electròdes, hardware electrònic i en el desenvolupament d'electrodes tèxtils han obert camí a poder crear equipament més petit i més fàcil de fer servir per a mesures de bioimpedància elèctrica. En aquesta tesi s'ha adaptat una placa basada en xip AD5933 dissenyada originàriament per a realizar la monitorizació de cos sencer d'edemes. Per a aquest objectiu s'han desenvolupat dues peces de software: un firmware en C per a controlar la placa i una interfície d'usuari en Visual Basic 2008 per a Windows per a monitoritzar i enregistrar fàcilment les dades mesurades. Aquesta tesi també presenta els resultats de tests de validació duts a terme en dos individus. Aquests resultats han sigut exportats i analitzats amb MATLAB per a mostrar la factibilitat d'usar aquest sistema per a monitoritzacions de llarga durada però no es pot extreure cap dada concloent sense primer realitzar més anàlisis.

Projecte realitat en col.laboració amb el centre Hogskolan i Boras (Suècia) In recent years, due to the combination of technological advances in the fields of measurement instrumentation, communications, home-health care and textile-technology the development of medical devices has shifted towards applications of personal healthcare. There are well known the available solutions for heart rate monitoring successfully provided by Polar and Numetrex. Furthermore new monitoring applications are also investigated. Among these non-invasive monitoring applications, it is possible to find several ones enable by measurements of Electrical Bioimpedance. Analog Devices has developed the AD5933 Impedance Network Analyzer which facilitates to a large extent the design and implementation of Electrical Bioimpedance Spectrometers in a much reduced space. Such small size allows the development of a fully wearable bioimpedance measurement. With the development of a Electrical Bioimpedance-enable wearable medical device in focus for personal healthcare monitoring, in this project, the issue of power management has been targeted and a battery-driven Electrical Bioimpedance Spectrometer based in the AD5933 has been implemented. The resulting system has the possibility to operate with a Li-Po battery with a power autonomy over 17 hours.

Objetivos: determinar la tasa de desnutrición en los pacientes con enfermedad de Crohn en nuestro medio (Subestudio A). Evaluar la respuesta de los pacientes desnutridos al tratamiento nutricional con un suplemento específico a largo plazo (Subestudio B). Sujetos: En el Subestudio A se incluyeron 98 pacientes con enfermedad de Crohn vistos consecutivamente sin selección previa, (51% mujeres) con una edad media de 39,2 ± 15,19 años, rango: 18-81 años. En el Subestudio B se incluyeron 19 pacientes con desnutrición moderada con enfermedad de Crohn (52% mujeres) con una edad media de 36,41 ± 5,2 años, rango: 19-45. Métodos: el diseño del Subestudio A fue un estudio observacional con una cohorte de pacientes con enfermedad de Crohn. El Subestudio B fue un estudio de intervención nutricional abierto, prospectivo y con control histórico. Las variables utilizadas fueron parámetros antropométricos, bioimpedancia eléctrica, medidas bioquímicas, índice de actividad de la enfermedad, valoración global subjetiva y tratamiento actual. Principales resultados: la tasa de desnutrición fue del 52%. El tipo de desnutrición más frecuente fue la desnutrición calórica (43%), seguida por una desnutrición mixta calórica-proteica. Se ha observado que el 34% de los pacientes presentaban ferropenia. Tras la terapia nutricional específica con suplemento enriquecido en TGF-β2 durante doce meses se ha observado un estacionamiento del peso y una mejoría de la evolución de la enfermedad determinada por un descenso del índice de actividad. Conclusiones: la tasa de desnutrición fue similar a la de estudios previos realizados en España. Nuestro estudio confirma la elevada tasa de ferropenia que sufren los pacientes con enfermedad de Crohn. La respuesta al tratamiento es favorable, sobre todo en lo que respecta a la historia natural de la enfermedad. Objetives: to determine the rate of malnutrition in patients with Crohn's disease in our area (Substudy A). We assess in long-term the response of malnourished patients to treatment of nutritional supplement with TGF-β2 (Substudy B). Subjects: ninety-eight (51% females) patients with Crohn's disease without selection, ages: 39.2 ± 15.19 years, range: 18-81 years were included in Substudy A. In Substudy B thirty-nine malnourished patients (52% females) were included with an average age of 36.41 ± 5.2 years and range: 19-45 (Substudy B). Methods: the design of the Substudy A was an observational and cross sectional study. Whereas, the Substudy B was a longitudinal, open intervention study with active (historical) control. The variables were anthropometric parameters, electrical bioimpedance, biochemical measures, index of disease activity, subjective global assessment and the kind of treatment that every patient has received. Main results: the malnutrition rate was 52%, being the most frequent the caloric malnutrition, followed by mixed malnutrition. Thirty four per cent of the patients had iron deficiency. Twelve months of nutritional therapy with supplement specifically enriched in TGF-β2 improved the evolution of the disease determined by a decrease in CDAI. Conclusions: The rate of malnutrition was similar to that of previous studies realized in Spain. Our study confirms the high rate of iron deficiency that the patients suffer with Crohn's disease. The response to the treatment is favorable, especially regarding the natural history of the disease.

Introducción. Gracias a la bioimpedancia es posible valorar el estado de hidratación del paciente independientemente del peso corporal. También identifica las reservas proteicas/magras y reservas grasas en el paciente. Objetivos. 1. Descripción del estado nutricional de la población estable en un centro periférico medido por: bioimpedancia, antropometría, valoración global subjetiva y datos analíticos. 2. Comparación y análisis de los diferentes métodos de valoración nutricional. Metodología. Estudio analítico, prospectivo, comparativo de diferentes formas de valorar el estado nutricional de los 52 pacientes estables de nuestro centro. Estudiamos la concordancia entre variables y comparamos parámetros significativos de cada método de valoración nutricional: Resultados. Por valoración global subjetiva encontramos alto riesgo de desnutrición en un 63,46%; de los pacientes, la bioimpedancia indica una malnutrición de un 59,61%. La albúmina sérica muestra un 56,8% de los pacientes con un estado nutricional adecuado, mientras que están en este estado un 51,21% si se considera la transferrina sérica. Existen muchos métodos para valorar el estado nutricional de nuestros pacientes. Se observa correlación entre la valoración global subjetiva y la analítica nutricional. Introduction. Thanks to bioimpedance it is possible to evaluate the state of hydration of the patient independently of body weight. It also identifies the lean protein reserves and fat reserves in the patient. Objectives. 1. Description of the nutritional state of the stable population in a peripheral centre measured by: bioimpedance, anthropometrics, subjective global assessment and analytical data. 2. Comparison and analysis of the different nutritional evaluation methods. Methodology. Analytical, prospective, comparative study of the different ways of evaluating the nutritional state of the 52 stable patients in our centre. We studied the match between variables and we compared significant parameters of each nutritional evaluation method: Results. By subjective global assessment we found a high risk of malnutrition in 63.46% of patients, bioimpedance indicated malnutrition in 59.61%. Serum albumin showed 56.8% of patients in an adequate nutritional state while 51.21% are in this state if serum transferrin is considered. There are many methods for evaluating the nutritional state of our patients. A correlation is observed between the subjective global assessment and the nutritional analysis.

Electrical Bioimpedance measurement has been used in clinical practice for several years for non-invasive monitoring. In recent years new applications of electrical bioimpedance measurements based in the spectral analysis has been validated.This fact have encouraged the use of spectral analysis on Electrical Bioimpedance measurements and it is a wide spread idea that spectral analysis of electrical bioimpedance data is going to open the door for new indicators for health assessment.The intended goal of this project is to develop a software tool, based in Matlab, that allows researchers to perform, both spectral and time signal analysis on the measurements performed Electrical Bioimpedance Spectrometers. This tool must incorporate the necessary display capabilities to allow quick visual inspection and visualization of the analysis results.Once this tool has been implemented, spectral analysis and validation of classification features will be possible in an easy way accelerating the process of test and analysis of experimental data analysis. This task is always critical in any research or clinical study.To facilitate the spectral analysis of electrical bioimpedance data will contribute to the developing of novel methods of non-invasive diagnosis and monitoring. Uppsatsnivå: D

Peritoneal Dialysis is a treatment for patients suffering from renal failure thatallows out-patient care. This means that the patient only needs to visit the hospital forconsultation and not for treatment, increasing considerably the comfort of the patient,while reducing remarkably the cost per patient.In order to increase the level of medical supervision obtained with the periodicvisits to the clinic, televisit has been put into practice in some hospitals. But thesetelevisits are based on indirect and qualitative indicators of renal failure, and thereforethey are just valid for detection of situations near limit cases, such as well over-hydratedor dehydrated.Electrical Bioimpedance Measurements have been proved to constitute anappropriate method for assessment of body composition, and therefore they can providewith direct indicators of body fluid distribution. Such ability of EBI technology allowsthe detection of body fluid unbalance caused by renal dysfunction, and therefore,nephrology televisits would benefit tremendously from EBI measurements.This project is based on the AD5933 Impedance Network Analyzer of AnalogDevices, and the main task is to develop a software application that controls theevaluation board in which it is implemented, and allows the storage of the EBImeasurements in EDF+ files that will facilitate the management of medical data whenapplied to televisit. These files are uploaded to XML format in order to be sent to aremote server, where a software application will have been implemented for medicalconsultation. Uppsatsnivå: D

Electrical impedance is a complex measure of resistance, represented not only with relative magnitudes of voltage and current, but also with the phase angle. The phase angle represents the value of phase shift between the voltage and the current. We have measured the electrical impedance of musculus gastrocnemius for two different groups of examinees. The first group was Croatian taekwondo team with both males and females, and the other was a group of students matched on age and sex. The magnitude (|Z|) and phase (φ ) of impedance were measured from 100 Hz do 1 MHz, by the HP 4284A impedance meter, using the Ag-AgCl ECG self adhesive electrodes. To achieve easier control of the instrument parameters, we have developed a computer application using the Microsoft .NET 2.0 framework. The results show the difference of mean value of |Z| between taekwondo athletes and students at high frequencies. We have ignored the impedance at lower frequencies because it is dominantly affected by the electrode and skin impedance and does not reflect the difference of the impedance of muscles. We have found that the mean value of |Z| is lower for males and higher for females in both tested groups. We have compared the differences that we noticed, with the results of conductivity and permittivity measurements of Gabriel and co-workers. The measured differences in impedance spectra indicate the structural difference of the leg tissue between the groups. We think that the higher mean value of |Z| in females is probably because of genetically conditioned enlarged quantity of subdermal adipose tissue. The observed difference in impedance between male taekwondo team and the group of male students are most likely related to the larger muscle mass in members of the taekwondo team.

Neurologically related injuries cause a similar number of deaths ascancer, and brain damage is the second commonest cause of death in theworld and probably the leading cause of permanent disability. Thedevastating effects of most cases of brain damage could be avoided if itwere detected and medical treatment initiated in time. The passiveelectrical properties of biological tissue have been investigated for almost acentury and electrical bioimpedance studies in neurology have beenperformed for more than 50 years. Even considering the extensive effortsdedicated to investigating potential applications of electrical bioimpedancefor brain monitoring, especially in the last 20 years, and the specificallyacute need for such non-invasive and efficient diagnosis support tools,Electrical Bioimpedance technology has not made the expectedbreakthrough into clinical application yet. In order to reach this stage inthe age of evidence-based medicine, the first essential step is todemonstrate the biophysical basis of the method under study. The presentresearch work confirms that the cell swelling accompanying thehypoxic/ischemic injury mechanism modifies the electrical properties ofbrain tissue, and shows that by measuring the complex electricalbioimpedance it is possible to detect the changes resulting from braindamage. For the development of a successful monitoring method, after thevital biophysical validation it is critical to have available the properelectrical bioimpedance technology and to implement an efficient protocolof use. Electronic instrumentation is needed for broadband spectroscopymeasurements of complex electrical bioimpedance; the selection of theelectrode setup is crucial to obtain clinically relevant measurements, andthe proper biosignal analysis and processing is the core of the diagnosissupport system. This work has focused on all these aspects since they arefundamental for providing the solid medico-technological backgroundnecessary to enable the clinical usage of Electrical Bioimpedance forcerebral monitoring.

Non-heart-beating donors sustain an ischemic insult of unknown severity and duration, which can compromise the viability of the graft. This preliminary study aimed to assess whether electrical bioimpedance monitoring of cold preserved organs could be useful to identify kidneys that have suffered previous warm ischemia (WI). Two rat groups were studied during 24 h of preservation in University of Wisconsin solution (UW): a control cold ischemia group and another group subjected previously to 45 min of WI. Multi-frequency bioimpedance was monitored during preservation by means of a miniaturized silicon probe and the results were modeled according to the Cole equation. Tissular ATP content, lactate dehydrogenase in UW solution and histological injury were assessed. Renal function and cell injury, evaluated during 3 h of ex vivo reperfusion using the isolated perfused rat kidney model, demonstrated differences between groups. Bioimpedance results showed that the time constant and the high frequency resistivity parameters derived from the Cole equation were able to discriminate between groups at the beginning of the preservation (Δτ ∼ 78%, ΔR∞ ∼ 36%), but these differences tended to converge as preservation time advanced. Nevertheless, another of the Cole parameters, α, showed increasing significant differences until 24 h of preservation (Δα ∼ 15%). © 2004 Elsevier B.V. All rights reserved., This work was supported by the European Commission through projects ESPPRIT-LTR-23485, IST-1999-13047 and QLK6-CT-2000-00064 and by the Spanish government through projects TIC98-1634-CE, TIC2000-2486-CE, FISS 01/1691 and SAF 2000-3090-CE, SAF 2003-04225 CE. Meritxell Genescà was supported by a grant from IDIBAPS

Thoracic electrical bioimpedance cardiography is a non-invasive, continuous and low-cost method of estimation of cardiac output and other haemodynamic parameters. Though subject to continuous technological refinement controversial opinions exist on its validity in subsets of critically ill patients, patients with heart disease or after cardiac surgery. A comparison study between thermodilution (TD) and bioimpedance (TEB) was performed in 28 patients undergoing elective cardiac surgery (CABG, aortic or mitral valve replacement or combined procedures). 128 pairs of cardiac index estimates at specific time points during 20 hours at the postoperative ICU were evaluated. A poor correlation (r = 0.26, p-1.m2, precision + 1.1 l.min-1.m-2, 95% limits of agreement -2.27 - 2.13 l.min-1.m-2) between TD and TEB cannot support the routine use of TEB monitoring in early postoperative period after open-heart surgery. Possible reasons of lack of agreement in this population are discussed. Further studies with technically improved bioimpedance cardiographs will be needed.

Electrical impedance spectroscopy (EIS) can be used to characterize biological materials in applications ranging from cell culture to body composition, including tissue and organ state. The emergence of cell therapy and tissue engineering opens up a new and promising field of application. While in most cases classical measurement techniques based on a frequency sweep can be used, EIS based on broadband excitations enables dynamic biological systems to be characterized when the measuring time and injected energy are a constraint. Myocardial regeneration, cell characterization in micro-fluidic systems and dynamic electrical impedance tomography are all examples of such applications. The weakness of such types of fast EIS measuring techniques resides in their intrinsic loss of accuracy. However, since most of the practical applications have no restriction over the excitation used, the input power spectrum can be appropriately designed to maximize the accuracy obtained from the measurements. This paper deals with the problem of designing the optimal multisine excitation for electrical bioimpedance measurements. The optimal multisine is obtained by the minimization of the Cramer–Rao lower bound, or what is the same, by maximizing the accuracy obtained from the measurements. Furthermore, because no analytical solution exists for global optimization involving time and frequency domains jointly, this paper presents the multisine optimization approach partially in both domains and then combines the results. As regards the frequency domain approach, a novel contribution is made for the multisine amplitude power spectrum. In the time domain, multisine is optimized by reducing its crest factor. Moreover, the impact on the information and accuracy of the impedance spectrum obtained from using different multisine amplitude power spectra is discussed, as well as the number of frequencies and frequency distributions. The theory is supported by a set of validation measurements when exciting with the optimal and flat multisine signals and compared to a single frequency ac impedance analyzer when characterizing an RC circuit. In vivo healthy myocardium tissue electrical impedance measurements show that broadband EIS based on multisine excitations enable the characterization of dynamic biological systems.

Background: Impedance plethysmography applied to the head by using a pair of electrodes attached to the scalp surface is known as bipolar Rheoencephalography or REG I and was originally proposed to measure changes in cerebral blood volume related to the heartbeat. REG I was soon discarded in favor of other REG configurations, since most of the signal was shown to be heavily contaminated by the extracranial blood flow. The main goal of this study was to identify and compare the part of the REG I signal caused by scalp blood flow with that originating from non-extracranial sources. Methods: A clinical study involving thirty-six healthy volunteers was designed for this purpose. REG I was first registered in each subject under normal conditions. A pneumatic cuff was then placed around the head and was inflated to arrest the scalp blood flow and a second REG I was recorded. Finally, a third REG I was taken immediately after cuff deflation. Results: The REG I signal is attenuated, but not extinguished, during cuff inflation in a wide subject-dependent range ratio from 0.12 to 0.68 (0.37 ± 0.15). The residual REG I signal has a waveform that is markedly different from that obtained before cuff inflation, which supports the hypothesis of the intracranial origin of the residual REG I signal. Additionally, an increase of 22% in REG I amplitude was observed when the head cuff was deflated. Conclusions: Waveform differences between extra and non-extracranial components are significant and these differences could be used in a method to distinguish one from the other. However, a significant part of the REG I signal is caused by a non-extracranial source and, therefore, it should not be used as a footprint of the extracranial blood flow., The author would like to thank E Guijarro, T Pons, P Ortiz, E Berjano and M Monserrat for their help and assistance in the development of this research. This research was supported by grant PI04/0303 from the Instituto de Salud Carlos III (Fondo de Investigacion Sanitaria) in the framework of the 'Plan Nacional de Investigacion Cientifica, Desarrollo e Innovacion Tecnologica (I + D + I)'.