Effect of oral nutritional supplementation combined with impedance vectors for dry weight adjustment on the nutritional status, hydration status and quality of life in patients on chronic hemodialysis: A pilot study.

BACKGROUND & AIMS: Protein energy wasting frequently affect hemodialysis patients and contribute to the development of overhydration. The objective of this study was to assess the effect of oral nutritional supplementation (ONS) combined with bioelectrical vector analysis (BIVA) on the nutritional and hydration status and the quality of life (QoL) in hemodialysis (HD) patients. METHODS: Thirty-two chronic HD patients were included in a 6-month randomized pilot study. Patients in SUPL group received a simultaneous intervention consisting of a personalized diet, 245 mL/d ONS and dry weight adjustment through BIVA. Patients in CON group received a personalized diet and dry weight adjustment by BIVA. Anthropometrical, biochemical, dietary, QoL, handgrip strength (HGS) and bioimpedance measurements were performed. Malnutrition Inflammation Score (MIS) was applied. RESULTS: At the end of the intervention, moderate undernutrition decreased by 43.8% in SUPL group while in CON group, severe undernutrition increased by 13% (p < 0.04 between groups). In the adjusted covariance analysis, SUPL compared to CON group, increased HGS (Δ 2.8 Kg vs Δ -1.8 Kg, p = 0.003), serum albumin (Δ 0.29 g/dL vs Δ -0.03 g/dL, p = 0.04) and serum transferrin (Δ 4.7 mg/dL vs Δ -0.7 mg/dL, p = 0.0007). The increase in QoL was significantly higher in SUPL group. Dry weight was achieved in 100% of patients in SUPL and 95% in CON group. CONCLUSIONS: ONS combined with BIVA for dry weight adjustment, improved nutritional status, QoL and achieved dry weight in HD patients.

Hydration status according to impedance vectors and its association with clinical and biochemical outcomes and mortality in patients with chronic kidney disease / Estado de hidratación por vectores de impedancia y su asociación con desenlaces clínicos, bioquímicos y mortalidad en pacientes con enfermedad renal crónica

Background: the evaluation of hydration status and body composition in patients with kidney disease is vital for proper management, since overhydration is associated with cardiovascular complications. Patients with chronic kidney disease (CKD) begin to show perceptible alterations in hydration during the intermediate stages of the disease; however, there is little information regarding the evaluation of blood volume status through bioelectrical impedance vector analysis (BIVA) in this population. Objective: to determine the association between hydration status measured with BIVA and biochemical and clinical parameters and mortality in patients with stage G3a, G3b and G4 CKD. Material and methods: a cross-sectional study was conducted with patients with stage G3a, G3b and G4 CKD who underwent bioelectrical impedance analysis (BIA). The following biochemical and clinical parameters were determined: serum and urinary albumin, hematocrit, serum electrolytes and creatinine, estimated glomerular filtration rate (eGFR, using the CKD-EPI formula), 24-hour urine output and blood pressure. The clinical and biochemical variables were associated with the components of the BIA. According to the resistance/height (R/H) and reactance/height (Xc/H) values, the BIVA results were individually plotted on reference ellipses to identify patients with abnormal hydration states. The patients were classified by group according to hydration status and CKD stage z-scores, and differences in clinical, biochemical and BIA parameters were identified. Mortality was determined by hydration status. (AU)

Antecedentes: la evaluación del estado de hidratación y la composición corporal es imprescindible para los pacientes con enfermedad renal crónica (ERC) en estadios intermedios, ya que en esta etapa inician con alteraciones hídricas perceptibles; sin embargo, existe poca información en dicha población sobre la evaluación del estado de volemia mediante el análisis de vectores de bioimpedancia eléctrica (BIVA). Objetivo: asociar el estado de hidratación medido por BIVA con parámetros bioquímicos, clínicos y mortalidad en pacientes con ERC G3a G3b y G4 Material y métodos: estudio transversal en el cual se incluyó a pacientes con ERC en estadios G3a G3b y G4 a los que se les realizó un análisis de impedancia bioeléctrica (IBE) y en los que se determinaron parámetros bioquímicos y clínicos: albúmina sérica y urinaria, hematocrito, electrólitos y creatinina séricos, tasa de filtrado glomerular estimada (TFGe) (fórmula CKD-EPI), diuresis de 24 horas y presión arterial. Las variables clínicas y bioquímicas se asociaron con los componentes de la IBE. Los valores de resistencia/estatura (R/H) y reactancia/estatura (Xc/H) se graficaron individualmente sobre las elipses de referencia para identificar a pacientes con estados de hidratación anormales. Se ubicaron grupos según el estado de hidratación y estadio de ERC en z-score y se identificaron las diferencias de parámetros clínicos, bioquímicos y de IBE. Se determinó la mortalidad según el estado de hidratación. (AU)

Agreement between vector analysis and body composition measurements by four types of bioelectrical impedance technology in hemodialysis patients / Concordancia del análisis vectorial y medidas de composición corporal de cuatro tipos de tecnología de impedancia bioeléctrica en pacientes en hemodiálisis

Background: the differences in bioelectrical impedance vector analysis (BIVA) results from different analyzers that use different bioelectrical impedance analysis (BIA) measurement technologies are not known. This study aimed to identify the degree of agreement between the BIVA results of four different BIA measurement techniques and to evaluate the degree of agreement between their estimates of fat-free mass (FFM) and fat mass (FM) and those determined by the gold-standard method of dual-energy X-ray absorptiometry (DEXA) in a subgroup of patients without overhydration. Methods: a cross-sectional study was conducted with hemodialysis (HD) patients with end-stage renal disease (ESRD) aged 18 to 65 years. BIA was measured with four different techniques: spectroscopic (BIA-BIS), multifrequency (BIA-MF), single-frequency (BIA-SF), and segmental multifrequency (BIA-MS) techniques. The differences and concordance between the components of the BIA (resistance, reactance, and phase angle) of the four devices were analyzed. Patients with a normal hydration status were identified, and concordance between FM and FFM measurements with each impedance device and DEXA was observed only in these patients. Results: thirty patients were included. The concordance between the components of BIA ranged from good to excellent (phase angle: intraclass correlation coefficient (ICC) = 0.82, 95 % confidence interval (CI): 0.77-0.93; resistance: ICC = 0.98, 95 % CI: 0.92-0.99). The overall concordance for BIVA diagnosis between the analyzers was substantial for hydration (k = 0.71, 95 % CI: 0.71-0.72) and for body tissues (k = 0.68, 95 % CI: 0.67-0.68). Bland–Altman plots showed the lowest bias between BIA-BIS and DEXA for both FM and FFM. (AU)

Antecedentes: se desconoce si existen diferencias en el diagnóstico dado por el análisis de vectores de impedancia bioeléctrica (BIVA por sus siglas en inglés) entre los analizadores que utilizan distintas tecnologías de medición de impedancia bioeléctrica (IBE). Este estudio tuvo como objetivo identificar el grado de concordancia entre el diagnóstico por BIVA de cuatro técnicas diferentes de medición de IBE, así como evaluar el grado de concordancia entre sus estimaciones de masa magra (MM) y masa grasa (MG) en comparación con el método de absorciometría de rayos X de energía dual (DEXA) en un subgrupo de pacientes sin sobrecarga de volumen. Métodos: se realizó un estudio transversal en pacientes con enfermedad renal crónica avanzada (ERCA) en hemodiálisis (HD) con edades entre los 18 a 65 años. La IBE se midió con cuatro diferentes tecnologías: espectroscópica (IBE-BIS), multifrecuencia (IBE-MF), una sola frecuencia (IBE-SF) y multifrecuencia segmental (IBE-MS). Se analizaron las diferencias y concordancias entre los componentes de la IBE (resistencia, reactancia y ángulo de fase) de los cuatro analizadores. Se identificaron pacientes con estado de hidratación normal, y solo en ellos se evaluó la concordancia de FFM y FM entre cada analizador de impedancia y DEXA. Resultados: se incluyeron 30 pacientes. La concordancia entre los componentes del IBE varió de buena a excelente (ángulo de fase: coeficiente de correlación intraclase (ICC) = 0,82, IC del 95 %: 0,77-0,93; resistencia: ICC = 0,98, IC del 95 %: 0,92-0,99). La concordancia general en el diagnóstico de BIVA entre los analizadores fue substancial para la hidratación (k = 0,71, IC del 95 %: 0,71-0,72) y los tejidos corporales (k = 0,68, IC del 95 %: 0,67-0,68). Los gráficos de Bland-Altman mostraron un sesgo más bajo entre BIA-BIS y DEXA tanto para FM como para FFM. (AU)

Frequency of Intradialytic Hypotension Events Do Not Increase with Oral Nutritional Supplementation during Hemodialysis Treatment: A Randomized Controlled Trial.

OBJECTIVE: This study aimed to compare the effect of the use of a renal-specific oral nutritional supplement (RS-ONS) during hemodialysis sessions and the use of RS-ONS at home on the incidence of intradialytic hypotension. METHODS: A single-center, 12-week, open-label, randomized controlled clinical trial was conducted. The intervention was a RN-ONS divided into two portions: 100 and 137 mL. The first portion was given after 1 hour of hemodialysis (HD) treatment, while the second portion was given 45 minutes before the end of HD. The research staff registered the baseline and final nutritional parameters and systolic arterial pressure (SAP) from the screen of the HD device during 36 HD sessions. Hypotension symptoms were also recorded every hour during each HD session. The nutritional and functional status was also assessed. RESULTS: We registered a total of 16 hypotensive events during 1082 HD sessions: 9 were in patients supplemented at home (551 HD sessions) and 7 occurred in patients supplemented during HD P = .668. Incidence of intradialytic hypotension (IH) during 1082 HD sessions was 1.4%. The total malnutrition inflammation score (MIS) decreased in both groups (P < .01), and the percentage of cachexia improved in the supplemented-during-HD group (P < .05). CONCLUSIONS: In this randomized controlled trial, intradialytic hypotension events did not increase with the RS-ONS during HD treatment. This strategy appears to be a safe anabolic nutritional strategy for the prevention of PEW, selecting stable patients and administering a fractioned volume of the supplement after the first hour of HD treatment. More studies with larger samples size are required to confirm these findings.

SURVEY ON THE PERCEPTION OF HEALTH PROFESSIONALS ON THE USE OF INTRADIALYTIC ORAL NUTRITION IN PATIENTS UNDER HEMODIALYSIS.

BACKGROUND: Intradialytic oral nutrition (ION) has been shown to improve many clinical outcomes, including lowering mortality, in hemodialysis (HD) patients. Despite the benefits, ION is underused in many countries. OBJECTIVE: The objective of our study was to determine the perception of health-care professionals (HCP) in our environment of the use of ION in patients undergoing HD. METHODS: Survey applied to HCP in Mexico who worked or had worked in an HD unit in their locality. RESULTS: From 272 HCP who answered the survey, 74.3% believed that the use of ION has at least one beneficial effect; of these, the most frequently mentioned were an improvement in quality of life (QoL) (54.7%) followed by an improvement in serum albumin (37.9%) and muscle anabolism (31.6%). However, 49% consider that its use involves some risks. Of the respondents, 22% reported that their HD units allowed patients to consume food or supplements during HD sessions; the main reason given to forbid the introduction of food or supplements was the clinic's policy (41%). CONCLUSIONS: The personnel surveyed heterogeneous opinions regarding ION, but most believe that it may improve the QoL or the nutritional status of the patients. Nevertheless, the use of ION is uncommon in our country as it is against the internal regulations of most HD units.

Survey on the perception of health professionals on the use of intradialytic oral nutrition in patients under hemodialysis

Abstract Background Intradialytic oral nutrition (ION) has been shown to improve many clinical outcomes, including lowering mortality, in hemodialysis (HD) patients. Despite the benefits, ION is underused in many countries. Objective The objective of our study was to determine the perception of health-care professionals (HCP) in our environment of the use of ION in patients undergoing HD. Methods Survey applied to HCP in Mexico who worked or had worked in an HD unit in their locality. Results From 272 HCP who answered the survey, 74.3% believed that the use of ION has at least one beneficial effect; of these, the most frequently mentioned were an improvement in quality of life (QoL) (54.7%) followed by an improvement in serum albumin (37.9%) and muscle anabolism (31.6%). However, 49% consider that its use involves some risks. Of the respondents, 22% reported that their HD units allowed patients to consume food or supplements during HD sessions; the main reason given to forbid the introduction of food or supplements was the clinic’s policy (41%). Conclusions The personnel surveyed heterogeneous opinions regarding ION, but most believe that it may improve the QoL or the nutritional status of the patients. Nevertheless, the use of ION is uncommon in our country as it is against the internal regulations of most HD units.

Relationship between Nutritional Status and Gastrointestinal Symptoms in Geriatric Patients with End-Stage Renal Disease on Dialysis.

Gastrointestinal symptoms (GIS) are common in patients with end-stage renal disease (ESRD) and are associated with nutritional risks resulting from low food intake. Little is known about the relationship between GIS and malnutrition in geriatric patients with ESRD. The main objective of this study was to determine the relationship between nutritional status and severity of GIS in geriatric patients on dialysis therapy. Clinically-stable geriatric patients (older than 60 years old) who were dialysis outpatients were included in this cross-sectional study. The severity of GIS was assessed using the Gastrointestinal Symptoms Questionnaire (GSQ, short version), with patients classified into three groups: mild, moderate, and severe. Nutritional status was evaluated with the Malnutrition Inflammation Score (MIS), anthropometric assessment, biochemical parameters, and bioelectrical impedance. Descriptive statistics were used and differences between groups were analyzed with ANOVA and Kruskal Wallis, with a p < 0.05 considered to indicate significance. Fifty patients completed the study; the median age was 67 years old. Twenty-three patients were on hemodialysis (HD) and 27 were on peritoneal dialysis (PD). No significant differences were found according to dialysis modality, presence of diabetes, or gender. Ninety percent of patients had at least one GIS. Poorer nutritional status (evaluated by MIS) was related to a higher severity of GIS. There were no significant differences with other nutritional parameters. Our study showed a high prevalence of GIS in geriatric patients. There were no differences in observed GIS values that were attributed to dialysis modality, gender, or presence of type 2 diabetes mellitus (DM2). Severe GIS values were associated with poorer nutritional status determined by MIS, however, there was no association with anthropometry, biochemical values, or bioimpedance vector analysis.

Combined assessment of nutritional status in patients with peritoneal dialysis using bioelectrical impedance vectors and malnutrition inflammation score.

BACKGROUND AND OBJECTIVE: Protein energy wasting (PEW) is a common syndrome in patients with chronic kidney disease, related to changes in hydration status, decreased food intake and inflammation. There are several tools for the assessment and diagnosis of such alterations. Bioimpedance vector analysis (BIVA) assess the state of nutrition and hydration, but not the inflammatory component, while the malnutrition inflammation score (MIS) comprises the inflammatory and nutritional factors, but not the state of hydration. The aim of the study was to determine the concordance between MIS and BIVA to assess nutritional status in peritoneal dialysis patients. METHODS: We studied 50 patients on peritoneal dialysis which underwent  bioelectrical impedance measurements with an empty peritoneal cavity, also MIS was applied and biochemical parameters were evaluated. RESULTS: The prevalence of malnutrition with VIBE and MIS was 38% and 24% respectively. Statistically significant differences in body mass index (BMI) and phase angle between normally nourished and wasted patients by both methods were found. Body composition, biochemical parameters and impedance vectors were not statistically different between normally nourished and wasted patients. Concordance between methods was 0.314 (p = 0.019). CONCLUSIONS: Combined nutritional assessment with MIS and BIVA is necessary for the diagnosis of protein energy wasting syndrome in patients undergoing peritoneal dialysis.

Discordance between bioelectrical impedance vector analysis and the new ESPEN definition of malnutrition for the diagnosis of hospital malnutrition.

BACKGROUND & AIMS: No universally accepted diagnostic criteria for malnutrition are available to date. The aim was to assess the concordance for the diagnosis of hospital malnutrition between the bioelectrical impedance vector analysis (BIVA) and the new definition of malnutrition proposed by the European Society for Clinical Nutrition and Metabolism (ESPEN). METHODS: A total of 140 adult hospitalized patients were included. The malnutrition risk was assessed by the Nutritional Risk Screening. The ESPEN malnutrition criteria (body mass index (BMI) <18.5 kg/m2, weight loss (WL) + low BMI, and WL + low fat free mass index (FFMI) were applied to each patient. The bioelectrical impedance of each patient was measured, and malnutrition was diagnosed using the BIVA method. Diagnostic concordance between the BIVA and the new ESPEN definition was assessed with the Kappa coefficient. RESULTS: The malnutrition prevalence was higher with the BIVA vs ESPEN definition (22.1% vs 13.6%) in the global population and was similar (12.8% vs 12.1%) in the population at risk of malnutrition. The diagnostic performance of the BIVA was acceptable, with higher sensitivity in patients with fluid overload (FO) and more specificity in euvolemic patients. Diagnostic concordance between the BIVA and the ESPEN definition was poor for the global population (kappa = 0.56) and the population at risk of malnutrition (kappa = 0.67) but was acceptable in patients with FO (kappa = 0.78). However, the discordant BIVA+/ESPEN- patients classified as false positives for BIVA showed clinical and body composition data (low FFMI, low phase angle) consistent with malnutrition. CONCLUSIONS: According to the clinical and bioelectrical characteristics of the discordant BIVA+/ESPEN- patients, the BIVA could perform better that the new ESPEN definition for the diagnosis of hospital malnutrition, which should be confirmed with other studies.

Combined assessment of nutritional status in patients with peritoneal dialysis using bioelectrical impedance vectors and malnutrition inflammation score / Evaluación combinada del estado de nutrición en pacientes con diálisis peritoneal mediante vectores de impedancia bioeléctrica y puntaje de inflamación y desnutrición

Background and objective: Protein energy wasting (PEW) is a common syndrome in patients with chronic kidney disease, related to changes in hydration status, decreased food intake and inflammation. There are several tools for the assessment and diagnosis of such alterations. Bioimpedance vector analysis (BIVA) assess the state of nutrition and hydration, but not the inflammatory component, while the malnutrition inflammation score (MIS) comprises the inflammatory and nutritional factors, but not the state of hydration. The aim of the study was to determine the concordance between MIS and BIVA to assess nutritional status in peritoneal dialysis patients. Methods: We studied 50 patients on peritoneal dialysis which underwent bioelectrical impedance measurements with an empty peritoneal cavity, also MIS was applied and biochemical parameters were evaluated. Results: The prevalence of malnutrition with VIBE and MIS was 38% and 24% respectively. Statistically significant differences in body mass index (BMI) and phase angle between normally nourished and wasted patients by both methods were found. Body composition, biochemical parameters and impedance vectors were not statistically different between normally nourished and wasted patients. Concordance between methods was 0.314 (p = 0.019). Conclusions: Combined nutritional assessment with MIS and BIVA is necessary for the diagnosis of protein energy wasting syndrome in patients undergoing peritoneal dialysis (AU)

Antecedentes y objetivo: el desgaste energético proteico (DEP) es un síndrome muy común en pacientes con enfermedad renal crónica, en el que están involucrados alteraciones en el estado de hidratación, descenso de ingestión alimentaria e inflamación. Existen diversas herramientas para la evaluación y detección de dichas alteraciones. Los vectores de impedancia bioeléctrica (VIBE) evalúan el estado de nutrición e hidratación, pero no el componente inflamatorio, mientras que el puntaje de inflamación y desnutrición (MIS) comprende los factores inflamatorio y nutricional, pero no el estado de hidratación. El objetivo del estudio fue determinar la concordancia entre MIS y VIBE para evaluar el estado de nutrición en pacientes en diálisis peritoneal. Material y métodos: se estudió a 50 pacientes en diálisis peritoneal a los cuales se les realizaron mediciones de impedancia bioeléctrica con la cavidad peritoneal vacía, se aplicó el MIS y se evaluaron parámetros bioquímicos. Resultados: la prevalencia de desnutrición por MIS y VIBE fue del 38% y 24% respectivamente. Se encontraron diferencias estadísticamente significativas en índice de masa corporal (IMC) y ángulo de fase entre pacientes normonutridos y desgastados por ambos métodos. Las variables de composición corporal y bioquímicas entre pacientes normonutridos y desgastados por ambos métodos, así como los vectores de impedancia, no fueron estadísticamente diferentes. Se encontró una concordancia entre métodos de 0,314 (p = 0,019). Conclusiones: es necesaria la evaluación nutricia combinada con los métodos MIS y VIBE para un pertinente diagnóstico de desgaste energético proteico en pacientes en diálisis peritoneal (AU)

[Bioimpedance vector analysis as a tool for the determination and adjustment of dry weight in patients undergoing hemodialysis]. / VECTORES DE IMPEDANCIA BIOELÉCTRICA COMO HERRAMIENTA PARA LA DETERMINACIÓN Y AJUSTE DEL PESO SECO EN PACIENTES SOMETIDOS A HEMODIÁLISIS.

BACKGROUND AND OBJECTIVE: Overhydration in hemodialysis patients is associated with cardiovascular mortality. Adequate removal of liquids and achievement of dry weight is one of the main goals of therapy. So far there are no clinical or laboratory parameters that are reliable, simple and affordable for its determination. The bioelectrical impedance vector analysis (BIVE) is a tool that allows identifying and monitoring hydration status, so the aim of this study was to use BIVE to adjust the intensity of ultrafiltration and achieve dry weight in hemodialysis patients. METHODS: We studied 26 patients on hemodialysis, which were performed monthly measurements of bioelectrical impedance for four months. Corresponding vectors were plotted to know in an individual way the state of hydration, according to which the dry weight was adjusted when necessary. RESULTS: Dry weight adjustment was performed in 13 patients, 7 of which required increase and 6 decrease of dry weight. The displacement of vectors on the ellipses corresponded to the type of intervention made. Dry weight was reached in 84.6% of patients at the end of the study with a significant decrease in mean arterial blood pressure and an increase in phase angle in the group of decrease of dry weight. CONCLUSIONS: Bioelectrical impedance vector analysis is an useful tool for adjusting the dry weight in patients undergoing hemodialysis.

Antecedentes y objetivo: La sobrehidratación en los pacientes en hemodiálisis se asocia con mortalidad cardiovascular, por lo que la adecuada remoción de líquidos y el logro del peso seco es uno de los principales objetivos de la terapia. Hasta el momento no hay parámetros clínicos ni de laboratorio que sean confiables, sencillos y accesibles para su determinación. El análisis de vectores de impedancia (VIBE) es una herramienta que permite identificar y monitorizar el estado de hidratación, por lo que el objetivo de este estudio fue usar el VIBE para ajustar la intensidad del ultrafiltrado y alcanzar el peso seco en pacientes en hemodiálisis. Material y método: Se estudiaron 26 pacientes en hemodiálisis a los cuales se les realizaron medidas mensuales de impedancia bioeléctrica durante cuatro meses. Se graficaron los vectores correspondientes para conocer de manera individual el estado de hidratación, de acuerdo con lo cual se ajustó el peso seco en los casos necesarios. Resultados: Se realizó ajuste de peso seco en 13 pacientes, 7 de ellos necesitaron aumento de peso y 6 disminución del mismo. El desplazamiento de los vectores sobre las elipses correspondió al tipo de intervención realizada. Se logró alcanzar el peso seco en el 84.6% de los pacientes al final del estudio, con una disminución significativa de la presión arterial media y aumento del ángulo de fase en el grupo de disminución de peso seco. Conclusiones: El análisis de vectores de impedancia es útil para el ajuste del peso seco en los pacientes sometidos a hemodiálisis.

Vectores de impedancia bioeléctrica como herramienta para la determinación y ajuste del peso seco en pacientes sometidos a hemodiálisis / Bioimpedance vector analysis as a tool for the determination and adjustment of dry weight in patients undergoing hemodialysis

Antecedentes y objetivo: La sobrehidratación en los pacientes en hemodiálisis se asocia con mortalidad cardiovascular, por lo que la adecuada remoción de líquidos y el logro del peso seco es uno de los principales objetivos de la terapia. Hasta el momento no hay parámetros clínicos ni de laboratorio que sean confiables, sencillos y accesibles para su determinación. El análisis de vectores de impedancia (VIBE) es una herramienta que permite identificar y monitorizar el estado de hidratación, por lo que el objetivo de este estudio fue usar el VIBE para ajustar la intensidad del ultrafiltrado y alcanzar el peso seco en pacientes en hemodiálisis. Material y método: Se estudiaron 26 pacientes en hemodiálisis a los cuales se les realizaron medidas mensuales de impedancia bioeléctrica durante cuatro meses. Se graficaron los vectores correspondientes para conocer de manera individual el estado de hidratación, de acuerdo con lo cual se ajustó el peso seco en los casos necesarios. Resultados: Se realizó ajuste de peso seco en 13 pacientes, 7 de ellos necesitaron aumento de peso y 6 disminución del mismo. El desplazamiento de los vectores sobre las elipses correspondió al tipo de intervención realizada. Se logró alcanzar el peso seco en el 84.6% de los pacientes al final del estudio, con una disminución significativa de la presión arterial media y aumento del ángulo de fase en el grupo de disminución de peso seco. Conclusiones: El análisis de vectores de impedancia es útil para el ajuste del peso seco en los pacientes sometidos a hemodiálisis (AU)

Background and objective: Overhydration in hemodialysis patients is associated with cardiovascular mortality. Adequate removal of liquids and achievement of dry weight is one of the main goals of therapy. So far there are no clinical or laboratory parameters that are reliable, simple and affordable for its determination. The bioelectrical impedance vector analysis (BIVE) is a tool that allows identifying and monitoring hydration status, so the aim of this study was to use BIVE to adjust the intensity of ultrafiltration and achieve dry weight in hemodialysis patients. Methods: We studied 26 patients on hemodialysis, which were performed monthly measurements of bioelectrical impedance for four months. Corresponding vectors were plotted to know in an individual way the state of hydration, according to which the dry weight was adjusted when necessary. Results: Dry weight adjustment was performed in 13 patients, 7 of which required increase and 6 decrease of dry weight. The displacement of vectors on the ellipses corresponded to the type of intervention made. Dry weight was reached in 84.6% of patients at the end of the study with a significant decrease in mean arterial blood pressure and an increase in phase angle in the group of decrease of dry weight. Conclusions: Bioelectrical impedance vector analysis is an useful tool for adjusting the dry weight in patients undergoing hemodialysis (AU)

Vectores de impedancia bioeléctrica de referencia para la población española / Normal values of bioimpedance vector in Spanish population

Fundamento y objetivo: El análisis de vectores de impedancia es útil para la determinación de la composición corporal en pacientes con alteración del estado de hidratación. Las elipses de tolerancia originales fueron hechas en individuos sanos italianos. Debido a las diferencias en composición corporal entre poblaciones, el objetivo del estudio fue establecer elipses de tolerancia específicas para la población española y compararlas con las elipses realizadas en la población original de referencia. Material y método: Se estudiaron 311 sujetos sanos españoles de ambos sexos, entre 18 y 80 años, con IMC entre 18 y 31 Kg/m2 , a los cuales se les realizaron mediciones de peso, estatura e impedancia bioeléctrica. Los valores de resistencia y reactancia estandarizadas por la estatura (R/E y Xc/E) derivados de la medición de impedancia, fueron utilizados para determinar la composición corporal y realizar las elipses de referencias específicas para dicha población. Resultados: Las características de composición corporal fueron diferentes entre sexos y grupo etario. Se graficaron los valores de R/E y Xc/E de la población española sobre las elipses de tolerancia italianas, encontrándose que los vectores se situaban en los cuadrantes izquierdos, indicando diferente composición corporal, por lo que se construyeron elipses de tolerancia específicas para la población española a partir de los valores de R/E y Xc/E. Las elipses de tolerancia españolas fueron estadísticamente diferentes a las italianas. Conclusiones: Los vectores de la población española fueron diferentes a los de la población italiana, de ahí la importancia de tener un patrón de referencia propio (AU)

Background and objective: The bioelectrical impedance vector analysis is useful for the determination of body composition in patients with altered hydration status. The original tolerance ellipses were made in Italian healthy individuals. Due to differences in body composition between populations, the aim of the study was to establish specific tolerance ellipses for the Spanish population and compare them with those ellipses made in the original reference population. Methods: We studied 311 Spanish healthy subjects of both sexes, between 18 and 80 years old, with a BMI between 18 and 31 Kg/m2, who underwent measurements of weight, height and bioelectrical impedance. The values of resistance and reactance standardized by height (R/H and Xc/H) derived from the impedance measurement, were used to determine the body composition and construct the specific tolerance ellipses for this population. Results: The characteristics of body composition were different between sex and age groups. We plotted values of R/H and Xc/H of the Spanish population on the Italian tolerance ellipses finding that vectors were placed in left quadrants, indicating different body composition. We therefore built specific tolerance ellipses for Spanish population based on values of R/H and Xc/H. Spanish tolerance ellipses were statistically different from the Italian. Conclusions: The vectors of the Spanish population were different from those of the Italian, hence the importance of having a self-reference pattern (AU)

[Normal values of bioimpedance vector in Spanish population]. / Vectores de impedancia bioeléctrica de referencia para la población española.

BACKGROUND AND OBJECTIVE: The bioelectrical impedance vector analysis is useful for the determination of body composition in patients with altered hydration status. The original tolerance ellipses were made in Italian healthy individuals. Due to differences in body composition between populations, the aim of the study was to establish specific tolerance ellipses for the Spanish population and compare them with those ellipses made in the original reference population. METHODS: We studied 311 Spanish healthy subjects of both sexes, between 18 and 80 years old, with a BMI between 18 and 31 Kg/m², who underwent measurements of weight, height and bioelectrical impedance. The values of resistance and reactance standardized by height (R/H and Xc/H) derived from the impedance measurement, were used to determine the body composition and construct the specific tolerance ellipses for this population. RESULTS: The characteristics of body composition were different between sex and age groups. We plotted values of R/H and Xc/H of the Spanish population on the Italian tolerance ellipses finding that vectors were placed in left quadrants, indicating different body composition. We therefore built specific tolerance ellipses for Spanish population based on values of R/H and Xc/H. Spanish tolerance ellipses were statistically different from the Italian. CONCLUSIONS: The vectors of the Spanish population were different from those of the Italian, hence the importance of having a self-reference pattern.

Fundamento y objetivo: El análisis de vectores de impedancia es útil para la determinación de la composición corporal en pacientes con alteración del estado de hidratación. Las elipses de tolerancia originales fueron hechas en individuos sanos italianos. Debido a las diferencias en composición corporal entre poblaciones, el objetivo del estudio fue establecer elipses de tolerancia específicas para la población española y compararlas con las elipses realizadas en la población original de referencia. Material y método: Se estudiaron 311 sujetos sanos españoles de ambos sexos, entre 18 y 80 años, con IMC entre 18 y 31 Kg/m2, a los cuales se les realizaron mediciones de peso, estatura e impedancia bioeléctrica. Los valores de resistencia y reactancia estandarizadas por la estatura (R/E y Xc/E) derivados de la medición de impedancia, fueron utilizados para determinar la composición corporal y realizar las elipses de referencias específicas para dicha población. Resultados: Las características de composición corporal fueron diferentes entre sexos y grupo etario. Se graficaron los valores de R/E y Xc/E de la población española sobre las elipses de tolerancia italianas, encontrándose que los vectores se situaban en los cuadrantes izquierdos, indicando diferente composición corporal, por lo que se construyeron elipses de tolerancia específicas para la población española a partir de los valores de R/E y Xc/E. Las elipses de tolerancia españolas fueron estadísticamente diferentes a las italianas. Conclusiones: Los vectores de la población española fueron diferentes a los de la población italiana, de ahí la importancia de tener un patrón de referencia propio.

[Bioimpedance vector analysis for body composition in Mexican population]. / Vectores de impedancia bioeléctrica para la composición corporal en población mexicana.

OBJECTIVE: To construct bivariate tolerance ellipses from impedance values normalized for height, which can be used in Mexican population for the assessment of body composition and compare them with others made in different populations. METHODS: Body composition was assessed by bioelectrical impedance analysis (BIA) in 439 subjects (204 men and 235 women), 18 to 82 years old, with a BMI between 18-31, using an impedanciometer Quadscan 4000. Resistance, reactance and phase angle were used to calculate bioelectrical impedance vectors and construct bivariate tolerance ellipses. RESULTS: Mean age in men was 47.1 +/- 16 years and 42.4 +/- 13 for women, mean weight (73.4 + 9 vs. 60.1 + 8 kg) and height (1.68 vs. 1.55 m) were significant greater in men than in women (p < 0.002). Women in comparison with men, had greater values of impedance (622.96 +/- 66.16 S2 vs. 523.59 +/- 56.56 D) and resistance (618.96 +/- 66.10 Q 61.97 vs. 521.73 +/- 61.97 2), as well as of resistance and reactance standardized by height (398.24 +/-46.30 S2/m vs. 308.66 +/- 38.44) (44.32 +/- 7.14 i/m vs. 39.75 +/-6.29) respectively, with a significant difference in all of them (p < 0.0001). Similarly, the reactance was greater in females, nevertheless this difference did not reach statistical significance (68.96 +/- 11.17 vs. 67.18 +/- 10.3; p = 0.0861). The phase angle was greater in men than in women, with a statistically significant difference (7.330 +/- 0.88 vs. 6.360 +/- 0.97; p < 0.0001). Bivariate tolerance ellipses (50%, 75% and 95%) derived from Mexican subjects showed a significant upward deviation (p < 0.05) from previously published references from Mexican American and Italian populations. New ellipses of tolerance were therefore constructed for the Mexican population. CONCLUSIONS: Bioimpedance vectors in Mexican subjects are significantly different from the existing ones, supporting the need of population specific bivariate tolerance ellipses for the evaluation of body composition.

Vectores de impedancia bioeléctrica para la composición corporal en población mexicana / Bioimpedance vector analysis for body composition in Mexican population

Objective. To construct bivariate tolerance ellipses from impedance values normalized for height, which can be used in Mexican population for the assessment of body composition and compare them with others made in different populations. Methods. Body composition was assessed by bioelectrical impedance analysis (BIA) in 439 subjects (204 men and 235 women), 18 to 82 years old, with a BMI between 18-31, using an impedanciometer Quadscan 4000. Resistance, reactance and phase angle were used to calculate bioelectrical impedance vectors and construct bivariate tolerance ellipses. Results. Mean age in men was 47.1 ± 16 years and 42.4 ± 13 for women, mean weight (73.4 ± 9 vs. 60.1 ± 8 kg) and height (1.68 vs. 1.55 m) were significant greater in men than in women (p < 0.002). Women in comparison with men, had greater values of impedance (622.96 ± 66.16 Ω vs. 523.59 ± 56.56 Ω) and resistance (618.96 ± 66.10 Ω 61.97 vs. 521.73 ± 61.97Ω), as well as of resistance and reactance standardized by height (398.24 ± 46.30 Ω/m vs. 308.66 ± 38.44) (44.32 ± 7.14 Ω/m vs. 39.75 ± 6.29) respectively, with a significant difference in all of them (p < 0.0001). Similarly, the reactance was greater in females, nevertheless this difference did not reach statistical significance (68.96 ± 11.17 vs. 67.18 ± 10.3; p = 0.0861). The phase angle was greater in men than in women, with a statistically significant difference (7.33° ± 0.88 vs. 6.36° ± 0.97; p < 0.0001). Bivariate tolerance ellipses (50%, 75% y 95%) derived from Mexican subjects showed a significant upward deviation (p < 0.05) from previously published references from Mexican American and Italian populations. New ellipses of tolerance were therefore constructed for the Mexican population. Conclusions. Bioimpedance vectors in Mexican subjects are significantly different from the existing ones, supporting the need of population specific bivariate tolerance ellipses for the evaluation of body composition.

Objetivo. Realizar intervalos bivariados (elipses) de tolerancia a partir de las variables de impedancia estandarizadas por la estatura, las cuales pueden ser utilizadas en la población mexicana para determinar la composición corporal y comparar dichas elipses con las de otras elipses realizadas en otras poblaciones. Material y métodos. Se evaluó la composición corporal por impedancia bioeléctrica (IBE) en 439 sujetos (204 hombres y 235 mujeres), de 18 a 82 años de edad, con un IMC entre 18-31, utilizando un impedanciómetro Quadscan 4000. A partir de las mediciones de resistencia, reactancia y ángulo de fase se obtuvieron vectores de impedancia bioeléctrica para realizar elipses de tolerancia. Resultados. La edad promedio de los hombres fue de 47.1 ± 16 años y 42.4 ± 13 para las mujeres, el peso promedio (73.4 ± 9 vs. 60.1 ± 8) y la estatura (1.68 vs. 1.55 m) fueron significativamente mayores en hombres que en mujeres (p < 0.002). Las mujeres en comparación con los hombres, presentaron valores mayores de impedancia (622.96 ± 66.16 Ω vs. 523.59 ± 56.56 Ω) y resistencia (618.96 ± 66.10 Ω vs. 521.73 ± 61.97 Ω), así como de resistencia y reactancia estandarizadas por la estatura (398.24 ± 46.30 Ω/m vs. 308.66 ± 38.44 Ω/m) (44.32 ± 7.14 Ω/m vs. 39.75 ± 6.29 Ω/m), respectivamente, presentando en todas éstas una diferencia significativa (p < 0.0001). De igual manera, la reactancia fue mayor en el grupo femenino; sin embargo, esta diferencia no alcanzó significancia estadística (68.96 ± 11.17 vs. 67.18 ± 10.3; p = 0.0861). El ángulo de fase fue mayor en los hombres que en las mujeres, con una diferencia estadísticamente significativa (7.33° ± 0.88 vs. 6.36° ± 0.97; p < 0.0001). Las elipses de tolerancia (50%, 75% y 95%) elaboradas en población italiana sana fueron probadas para la población mexicana, encontrando que éstas tienden a situarse en el extremo superior de las elipses de poblaciones mexicoamericanas e italianas de referencia con una diferencia significativa p < 0.05, por lo que se realizaron nuevas elipses de tolerancia para población mexicana. Conclusiones. Los vectores de la población mexicana fueron significativamente diferentes al ser comparados con las existentes, apoyando la necesidad de realizar elipses de tolerancia específicas para cada población para la evaluación de la composición corporal.