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Objective: The main task of this work consists in an obtaining polarizable, dry mode, of bio-impedance sensors for non-invasiveECG monitoring, that work without any skin preparation or gel use, in two constructive models, based on conductive organicpolymer polypyrrole and polypyrrole with Ag nanoparticles (NP), as sensitive materials. Methods: The polypyrrole wassynthetized by chemical oxidative polymerization using FeCl3 as oxidant agent. For sensors fabrication two technological variantshave been chosen, a first variant realized by photolithographic method consisting in a substrate of Printed Circuit Board (PCB)with interdigitated copper electrode with step of 0.25 mm and over a distance of 12 mm and two pads. The polypyrrole orpolypyrrole with Ag NP dissolved in ethyl alcohol was deposed on the substrate by dipping method. The second model consists ina polypyrrole powder pressed at a hydraulic press at 10 tones/cm2 of force where one site was deposed a layer of Ag ink forconduction. Results: The performance of bio-impedance sensors were accessed by impedance skin-sensor interface withfrequency in the range of 10 - 300 kHz measurements. The influences of technological fabrication as shape and geometry as wellas the sensitive materials that used, in terms of impedance were analyzed. Conclusions: The introduction of Ag NP in polypyrrole,led to a better behavior, in terms of conduction and impedance response. For all tested sensors, the impedance decreases with thefrequency with a good linearity.
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Resumen Introducción: La bioimpedancia eléctrica multifrecuencia (BIE) evalúa con precisión la composición corporal. Objetivo: Investigar el estado nutricional y su relación con el índice de masa corporal (IMC) o el ángulo fase obtenido por BIE en pacientes con enfermedad renal terminal (ERT) en hemodiálisis. Método: En 99 pacientes en hemodiálisis (43.6 ± 17.2 años, 58.8 % varones) se evaluó IMC, BIE y puntuación de desnutrición (DMS, Dialysis Malnutrition Score). La independencia de las asociaciones del IMC y el ángulo fase con el DMS se determinó con regresión lineal múltiple. Resultados: El riesgo de desnutrición (DMS > 13) se incrementó gradualmente entre los sujetos con IMC y ángulo fase normales (44.4 %), IMC bajo (45.8 %), ángulo fase bajo (64.0 %) y en aquellos con ambos parámetros anormales (68.0 %). El ángulo fase fue la única variable asociada independientemente con el estado nutricional de los pacientes (coeficiente beta estandarizado −0.372, p < 0.001), lo que explicó 13.8 % de la variación en el DMS. Conclusiones: El ángulo fase se asocia inversa e independientemente con el riesgo de desnutrición en pacientes con ERT, lo que sugiere que la composición corporal evaluada por BIE pudiera ser mejor que el IMC en la valoración clínica de pacientes con esta enfermedad.
Abstract Introduction: Multi-frequency bio-impedance analysis (BIA) accurately evaluates body composition. Objective: To assess nutritional status and its relationship with body mass index (BMI) or with BIA-obtained phase angle in patients with end-stage renal disease (ESRD) on hemodialysis. Method: BMI, BIA and dialysis malnutrition score (DMS) were assessed in 99 patients on hemodialysis (43.6 ± 17.2 years of age, 58.8% males). Multivariate linear regression analysis was used to determine BMI and phase angle independent associations with DMS. Results: Malnutrition risk (DMS > 13) showed a gradual increase among patients with normal BMI and phase angle (44.4%), low BMI (45.8%), low phase angle (64.0%), and in those with both parameters at abnormal ranges (68.0%). The phase angle was the only variable that was independently associated with patient nutritional status (standardized coefficient beta −0.372, p < 0.001), accounting for 13.8% of DMS variation. Conclusion: Phase angle is inversely and independently associated with malnutrition risk in patients with ESRD, which suggests that BIA-assessed body composition might be better than BMI in the clinical assessment of patients with ESRD.
Subject(s)
Humans , Male , Female , Adult , Middle Aged , Aged , Young Adult , Renal Dialysis/methods , Electric Impedance , Malnutrition/epidemiology , Kidney Failure, Chronic/therapy , Body Composition , Body Mass Index , Nutritional Status , Cross-Sectional Studies , Malnutrition/diagnosis , Malnutrition/etiologyABSTRACT
Background: The alterations in the body composition (BC) in both the active and remission phase of Crohn’s disease (CD) are poorly characterized. Objective: To assess the BC of the patients with CD in active and remission phase, and compare with healthy controls (HC). Methods: BC was assessed by bioelectrical impedance analysis using Tanita TBF-215 leg to leg portable impedance analyzer in 123 patients with CD and 100 matched HC. Diet intake was assessed by 24 hours diet recall method. Results: The mean age of patients was 36.4+12.6 years and 56% were males. Patients in active phase as well as in remission phase had a lower BMI than HC (18.8+3.6 vs. 23.9+4.0; p=0.001 and 18.8+3.6 vs. 21.6+5.0; p=0.002). The fat mass (FM) in active phase was significantly lower than that in remission phase (8.2+5.9 vs. 13.4+10.6 kg; p=0.005) and HC (8.2+5.9 kg vs. 14.1+7.5 kg; p=0.001). FM did not differ between remission phase and HC. The fat free mass (FFM) of HC was significantly higher than that of both remission phase (48.9+7.4 kg vs. 43.3+10.4 kg; p=0.001) and active phase (48.9+7.4 kg vs. 40.7+8.5 kg; p=0.001). There was no difference in the FFM of patients in both phases; p=0.356. The intake of macronutrients was comparable between the two phases; however lower than that of HC. Conclusion: Both FM and FFM were depleted in the active phase, while only FFM was deficient in the remission phase of CD, indicating a poor recovery of lean mass in remission.
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Objective The Hilbert- Huang transformation (HHT) method was introduced to process the bio-impedance gastric motility signals from subjects.Methods Nonlinear and non-stationary original gastric motility series were decomposed into a number of intrinsic mode function (1MF) components by the empirical mode decomposition method (EMD).Hilbert transformation was carried out then and instantaneous frequency was extracted effectively.Gastric motility signal among 0.03-0.06 Hz was reconstructed from the IMF.Results The results suggested that HHT was a new and applicable time series analysis method based on mode decomposition and could extract impedance signal and remove the disturbances such as blood flow and breathing.Conclusion The new adaptive mode decomposition-based signal processing method provides a new method to investigate clinical gastric motility information.
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Objective To detect the gastric motility in patients with type 2 diabetes mellitus, and to explore the relationship between disorder of gastric motility in diabetes and the influential factors. Methods Sixty-five patients with type 2 diabetes mellitus and 30 health control subjects were collected. The gastric motility was tested with the signal processing device designed by Chongqing University of Posts and Telecommunications. The impedance and electrical signals were collected at the same time. Fasting blood glucose (FBG) was detected by oxidation enzyme method, while microcolumn method was adopted to test HbA1c. Results In the 65 patients with type 2 diabetes mellitus,the occurrence of abnormal gastric motility was 53.85% , they had several symptoms, such as abdominal distension, early satiety, and belching. The percentage of dominant frequency of impedance gastrogram in diabetes group was lower than that in the normal controls (P<0. 05 ). The percentage of dominant frequency of EGG in the abnormal HbA1c group( ≥6. 5% ) was significantly lower than that in the normal HbA1c group ( P<0. 01). The percentage of bradygastria in the elderly was higher than that in young and middle-aged subjects (P<0. 05), respectively. Disorder of gastric motility was not correlated with FBG and course of disease. Conclusions The incidence of disordered gastric motility is very high in patients with type 2 diabetes mellitus. Elderly patients and those with higher HbA1c are prone to suffer from disordered gastric motility. However, disorder in gastric motility is not correlated with FBG and duration of the illness.
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Este estudo teve como objetivo avaliar a hidratação dos alunos do Curso Básico Páraquedista (C Bas Pqdt - Curso de Formação dos Pára-quedistas Militares Brasileiros) de acordo com a variação da massa corporal e do calculo do total de líquidos corporais a partir do método de bioimpedância elétrica. A coleta de dados ocorreu durante as três semanas da 1ª fase do Curso Básico Pára-quedista, de 7 a 25 de janeiro de 2008. A amostra foi selecionada de forma aleatória entre os 422 alunos que iniciaram o curso. Participaram do estudo 90 militares do sexo masculino, voluntários, que podem ser caracterizados pelos seguintes dados antropométricos médios: idade(25,08 ± 3,96 anos); peso (76,53 ± 7,39 kg); altura (174,53 ± 5,85 cm) e percentual de gordura (14,07 ± 4,09). A perda hídrica percentual média foi de 3% do peso corporal e 46,7% dos sujeitos apresentaram níveis de desidratação superiores a essa média. Os resultados sugerem que a exposição ao estresse térmico e a relação volume X intensidadedo treinamento estão inadequadas, provocando uma acentuada velocidade de perda hídrica nos alunos do curso.
The aim of the present study was to evaluate hydration levels in the Basic Parachutist Course (BPC - the main program for Brazilian military parachutists training) students according to their body mass and total body water variations. To this end, a bio-impedance method was used in order to assess the subject?s fat percents. The data were collected during the 3 weeks of the first phase of the training course, January 7 - 25, 2008. The sample was randomly selected from the 422 volunteers who started the course. 90 male subjects participated in the study, and they can be characterized by the following anthropometric data: age (25.08 ± 3.96 years); weight (76.53 ± 7.39 kg); height (174.53 ± 5.85 cm) and fat percent (14.07 ± 4.09). The water loss average was 3% of the body weight and 46.7% of the subjects had higher levels of dehydration than the average. The results suggest that the course stress levels are not adequate, implying in an excessive water loss by its subjects.
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During the digest course the electrical property of the stomach alters obviously due to the change in shape, dimension, volume of gastric and the composition of stomach. The regulation of the impedance change is corresponding to the gastric motility and the correlation between them is evident. The impedance technique can be used to monitor gastric motility function no-invasively with high sensitivity and accuracy. Based on introduction of the gastric motility function and its measurement method, the development, key technique and existing problem of the gastric motility measurement using the electrical bio-impedance method are reviewed in this paper.
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This study proposes a new method for measuring upper limb movement using a bio-impedance technique. Bio-impedance and joint angle were simultaneously measured during the wrist and elbow movements of 12 normal subjects. The joint angles of the wrist and elbow were estimated by measuring the bio-impedances of the forearm and upper arm, respectively. Although the measured bio-impedances on upper limbs varied among individuals, changes in the bio-impedances and joint angles of the wrist and elbow during their extension and flexion were very highly correlated, having correlation coefficients of 0.96 +/- 0.04 and -0.98 +/- 0.02, respectively. The reproducibilities of wrist and elbow bio-impedance changes were 2.1 +/- 1.0% and 1.8 +/- 1.0%, respectively. Since the proposed method is not restricted by size or the duration of measurements, it is expected to be useful for the analysis of athletic movement.