Assessment of body composition by dual-energy X-Ray absorptiometry in renal transplant patients, hemodialysis patients, and a control group of healthy subjects.

BACKGROUND: The clinical findings of patients with Chronic Kidney Disease (CKD), which is characterized by malnutrition, sedentary lifestyle, uremia, and catabolism associated with dialysis produce changes in Body Composition (BC), causing increased Fat Mass (FM), decreased in both Lean Mass (LM) and Body Mineral Density (BMD), even despite uremic reversal after a Kidney Transplant (KT); immunosuppressive medications alter BC, increasing the risk of loss of the kidney transplant and cardiovascular diseases. OBJECTIVE: To demonstrate whether there are differences in BC between a group of patients with KT and a group of patients on Hemodialysis (HD), when comparing them with a control group without the disease. MATERIALS AND METHODS: In the present observational study, with a comparative design; 125 patients were evaluated (46 with KT, 47 on HD, and 32 from the healthy control group). The BC was evaluated with the full-body Dual-Energy X-Ray Absorptiometry (DEXA) method. RESULTS: The mean age and standard deviation (X±SD) of the study subjects were: 28.89 ± 5.76, 27.39 ± 5.04, and 29.63 ± 6.34 years for the HD, KT, and control subjects, respectively. The HD patients presented a total FM of 14.98 ± 6.96 kg in comparison with 20.1 ± 6.5 kg for the control group (p = 0.007), and 19.06 ± 7.94 kg for the group with KT (p = 0.02). The total LM was lower in the KT patients in comparison with the control group (p = 0.023). The content and total BMD were lower in both groups of patients with KT and HD. CONCLUSIONS: Although a comprehensive improvement in BC was expected after kidney transplantation, the results are not close to "normal' values, when compared with those of healthy subjects of the same age.

Electrical bioimpedance analysis and comparison in biological tissues through crystalloid solutions implementation.

Electrical bioimpedance is a non-invasive and radiation-free technique that was proposed to be used in different clinical areas, however, its practical use is limited due to its low capacity to discriminate between tissues. In order to overcome this limitation, our research group proposes to incorporate the contrast media into the electrical bioimpedance procedure. The main objective of the present study was to assess the crystalloid solutions as a possible contrast media to discriminate between different tissue types in the bioimpedance technique. Two medical-grade crystalloid solutions (Hartmann and NaCl 0.9%) were injected into three biological ex vivo models: kidney, liver, and brain. BIOPAC system was used to acquire bioimpedance data before and after the injections. The data was adjusted to the Debye electrical model. The analysis of measured values showed substantial bioimpedance disparities in tissues subjected to isotonic solutions. The NaCl solution exhibited more pronounced changes in electrical parameters compared to the Hartmann solution. Similarly, NaCl solution displayed superior discriminatory capabilities among tissues, with variations of 465%, 157%, and 206%. Distinct spectral modifications were identified, with tissues demonstrating unique responses at each frequency of analysis relative to untreated tissue. Variations in bandwidth alterations were discernible among tissues, providing clear distinctions. In conclusion, the research showed that the crystalloid solution exhibited greater sensitivity and superior tissue contrast at specific frequencies. This study's findings underscore the feasibility of implementing crystalloid solutions to enhance tissue discrimination, similar to the effects of contrast agents.

Electrical Impedance Tomography to Measure Spirometry Parameters in Chronic Obstructive Pulmonary Disease Patients / Tomografía por Impedancia Eléctrica para Medir Parámetros de Espirometría en Pacientes con Enfermedad Pulmonar Obstructiva Crónica

ABSTRACT Spirometry is a test for the diagnosis of chronic obstructive pulmonary disease. It is a technique that can be intolerant due to the essential use of a mouthpiece and a clamp. This study proposes the use of electrical impedance tomogra phy to measure respiratory parameters. Patients underwent spirometry and three respiratory exercises. The imped ance signals were convolved, and the resultant was analyzed by fast Fourier transform. The frequency spectrum was divided into seven segments (R1 to R7). Each segment was represented in terms of quartiles (Q25%, Q50%, Q75%). Each quartile of each segment was correlated with the spirometric parameters to obtain a fitting equation. FVC was correlated 70% with the 3 quartiles of R7, 3 equations were obtained with a fit of 60%. FEV1 correlated 70% with the Q50% of R7, obtaining an equation with a fit of 40%. FEV1/FVC correlated 69% with Q75% of R2, obtaining an equation with a fit of 60%. Spirometric parameters can be estimated from the implied carrier frequency components of the ventilatory impedance signal.

RESUMEN La espirometría es una prueba para el diagnóstico de enfermedad pulmonar obstructiva crónica. Es una técnica que puede resultar intolerante debido al uso imprescindible de una boquilla y una de pinza. Este estudio propone el uso de la tomografía de impedancia eléctrica para medir los parámetros respiratorios. Los pacientes realizaron una espi rometría y tres ejercicios respiratorios. Las señales de impedancia fueron convolucionadas, y la resultante se analizó mediante una transformada rápida de Fourier. El espectro en frecuencias se dividió en siete segmentos (R1 a R7). Cada segmento se representó en términos de cuartiles (Q25%, Q50%, Q75%). Cada cuartil de cada segmento se co rrelacionó con los parámetros espirométricos para obtener una ecuación de ajuste. La FVC se correlacionó en un 70% con los 3 cuartiles de R7, se obtuvieron 3 ecuaciones con un ajuste del 60%. El FEV1 se correlacionó en un 70% con el Q50% de R7, obteniéndose una ecuación con un ajuste del 40%. El FEV1/FVC se correlacionó en un 69% con el Q75% de R2, obteniéndose una ecuación con un ajuste del 60%. Los parámetros espirométricos pueden ser estimados a partir de los componentes de frecuencia portadora implícitos de la señal de impedancia ventilatoria.

Electrogastrographic and autonomic nervous system responses to solid and liquid meals in youth with functional dyspepsia.

BACKGROUND: Meal-related symptoms are common in paediatric functional dyspepsia (FD). There are only a small number of paediatric studies assessing mechanisms for meal-related symptoms, and these have not utilized Rome IV criteria. The aim of the current study was to assess gastric myoelectric and autonomic nervous system (ANS) responses to both liquid and solid meals in youth with Rome IV-defined FD. METHODS: In healthy controls (N = 14) and youth with FD (N = 12), we recorded electrocardiograph (to assess heart rate variability; HRV) and electrogastrograph (EGG) signals before and after two test meals, one liquid and one solid. EGG parameters and HRV were assessed for the entire pre- and postprandial periods and in short time intervals. Additionally, liquid gastric emptying was assessed utilizing a 13 C-acetate breath test. KEY RESULTS: During the EGG, the dominant power increased with both meals in controls but not patients with FD. During HRV assessment, the low frequency to high frequency ratio was higher after the liquid meal in controls, despite being similar preprandial, as compared to patients with FD. In controls, both standard deviation of normal to normal waves (SDNN) and root mean square of successive ECG R peaks (R-R interval) differences (rMSSD) increased after the liquid meal (but not after the solid meal) in controls but not patients with FD. CONCLUSIONS AND INFERENCES: Youth with Rome IV-defined FD lacks the normal postprandial EGG dominant power response or autonomic nervous system response following a liquid meal. The latter appears to indicate a lack of ANS flexibility.

Heart Rate Variability and Gastric Electrical Response to a Cold Pressor Task in Youth with Functional Dyspepsia.

BACKGROUND/AIMS: While stress has been implicated in functional dyspepsia (FD), the mechanisms by which stress results in symptoms are not well defined. The aim of the current study was to assess gastric myoelectric and autonomic changes in response to a physical stressor in youth with FD. METHODS: In a group of healthy controls and pediatric FD subjects, we recorded ECG and EGG signals 30 min before and 60 min after, a cold pressor task (CPT). Gastric EGG and heart rate variability (HRV) parameters were calculated in pre- and post-CPT stages and in short intervals. RESULTS: The pre-CPT percent tachygastria was higher in FD subjects as compared to controls. However, CPT did not induce any EGG changes in either controls or FD subjects and the two groups did not differ from each other post-CPT. The CPT resulted in an increase in HRV and standard deviation of NN intervals in controls; there was no change in any HRV parameter in FD subjects. CONCLUSIONS: Acute physical stress does not appear to induce gastric electrical abnormalities in youth with FD. Youth with FD appear to lack the normal flexible autonomic response to a physical stressor.