Bioelectrical Impedance Vector Analysis Method Research Articles

Association between BMI z-score and body composition indexes with blood pressure and grip strength in school-age children: a cross-sectional study

Childhood obesity is linked to diverse health outcomes, including elevated blood pressure (EBP). Emerging evidence showed that excess fat mass (FM) may have a deleterious impact on blood pressure even in normal-weight children. The primary objective of this study was to assess the association between body weight status by BMI z-score and body composition parameters by conventional bioelectrical impedance analysis (BIA) and bioelectrical impedance vector analysis (BIVA). Also, we aimed to explore the performance of BMI z-score, %FM, and FM index (FMI) in discriminating EBP in a sample of school-age Mexican children. Children were classified as having normal weight, overweight or obesity according to WHO criteria for BMI z-score. FMI was considered high when above 75th percentile, and fat free mass index (FFMI) was considered low when below 25th percentile of the reference population. Body composition was also classified according to the BIVA method and EBP was determined when systolic and/or diastolic blood pressure ≥ 90th percentile. BMI z-score groups were compared by Student´s t-test or the Mann–Whitney U test, or by the chi-square test or Fisher exact test. Receiving operating characteristic (ROC) analysis was performed. 61 children were included (52.5% boys, median age 9.8 (25th, 75th percentiles: 8.5, 11.0)) years. High FMI was observed in 32.3% of children with normal weight. Low FFMI was present in 93.5% of children with normal weight and 53.3% of those with overweight/obesity. According to BIVA, 58.1% and 43.3% of children with normal weight and overweight/obesity were classified as having cachexia. All the three adiposity indicators showed significant areas under the ROC curve (AURC) greater than 0.775 for EBP, with the largest one displayed for FM% (0.794). Hight FMI and low FFMI are common in children with normal weight. Identifying deficiency of FFM might be limited by using solely BMI indicators. Cachexia by BIVA was present in a high proportion of children with either normal weight or overweight/obesity. Both BMI z-score and FM (% and FMI) performed well at discriminating EBP, with a numerically greater AURC observed for FM%. Body composition in pediatric population is relevant for identifying body composition abnormalities at early age.

Bioimpedance vector analysis in stable chronic heart failure patients: Level of agreement between single and multiple frequency devices.

The accuracy of estimating body composition compartments is critical in the clinical setting. Currently, there are different bioelectrical impedance analysis (BIA) devices available for obtaining raw BIA parameters. The aim of this study was to determine the level of agreement between multiple frequency (MF)-BIA and single frequency (SF)-BIA devices in obtaining raw BIA measurements (resistance (R), reactance (Xc), and phase angle (PhA)), as well as the agreement on the classification of hydration status and body cell mass by the bioelectrical impedance vector analysis (BIVA) method. This cross-sectional study included 406 outpatients with stable chronic heart failure (HF). The raw BIA measurements at 50kHz obtained by tetrapolar MF-BIA (Bodystat QuadScan 4000) were compared with those obtained by tetrapolar SF-BIA (RJL Quantum X). In addition, the patients were classified by their hydration status and body cell mass according to the BIVA method. Strong and significant correlations were observed between the two methods in all raw BIA variables (r≥0.90). Lin's concordance correlation coefficient (CCC) values were almost perfect for R (CCC=0.99; 95% CI 0.997 to 0.998), moderate for Xc (CCC=0.93; 95% CI 0.92 to 0.94), and poor for PhA (CCC=0.88; 95% CI 0.85 to 0.90). The agreement obtained in the two classifications (quadrants and hydration status) was >0.81. MF-BIA and SF-BIA demonstrated good agreement for measurement of the R parameter; however, the Xc and PhA parameters must be used carefully due to the previously reported variability. Likewise, the agreement in all classifications by the BIVA method was almost perfect.

Bioelectrical impedance vector analysis evaluates cellularity and hydration in cirrhotic patients.

BACKGROUNDMalnutrition in cirrhotic patients is correlated with mortality and a better response to liver transplantation. However, recovery of the nutritional status in these patients is a challenge due to the difficulty in establishing a reliable nutritional diagnosis. The bioelectrical impedance vector analysis (BIVA) method appears as a feasible tool in clinical practice to define the physiological state of cirrhotic patients by assessing hydration and body cellularity.AIMTo evaluate body composition in cirrhotic patients using BIVA.METHODSThis retrospective cross-sectional study was carried out by following cirrhotic outpatients at a hospital in Porto Alegre, Brazil. A tetrapolar bioelectrical impedance analysis device was used to evaluate cellularity and hydration and to perform the BIVA. The BIVA graphic was elaborated by software and for statistical analysis a significance level of 5% (P ≤ 0.05) was considered.RESULTSOne hundred and ninety patients, 61.1% males, with a mean age of 56.6 ± 11.0 years, were evaluated. Of these, 56.3% had Child-Turcotte-Pugh (CTP) A score, and the prevalent etiology was hepatitis C virus (47.4%). The patients were classified according to cellularity and hydration by the quadrants and ellipses of the BIVA method, quadrant 1 (47.9%); quadrant 2 (18.9%); quadrant 3 (14.2%); and quadrant 4 (18.9%). Those classified in quadrant 1 and 2 had a higher phase angle compared to those in quadrants 3 and 4 (P < 0.001). Quadrant 2 patients had a lower average age than the other groups. The association with CTP score showed that patients in quadrant 2 had a higher proportion of CTP A, and those in quadrant 4 had a higher proportion of CTP C (P < 0.052).CONCLUSIONThe BIVA method allows identification of the cellularity and hydration status of cirrhotic patients, and its association with clinical factors determines the disease severity, age and prognostic index.

Relationship Between Bioimpedance Vector Displacement and Renal Function After a Marathon in Non-elite Runners.

Purpose: This study investigates the relationship between whole-body bioimpedance vector displacement, using bioelectrical impedance vector analysis (BIVA), and renal function through serum biomarkers [creatinine, urea, sodium, C-reactive protein (CRP), and creatine kinase] and urine biomarkers after a marathon.Methods: Bioimpedance measurements were taken among 19 non-elite runners at 24 h pre-race, immediately post-race, and at 48 h post-race. The bioimpedance measurements were analyzed by BIVA using the Hotelling’s T2 test. The runners were divided according to a cutoff of serum creatinine level immediately post-race in G1 (<1.2 mg/dl of serum creatinine level) and G2 (≥1.2 mg/dl of serum creatinine level). The increase of the serum creatinine levels in 83% of G2 runners was related to acute kidney injury (AKI) stage 1.Results: Neither G1 nor G2 showed a creatinine clearance rate (CCr) lower than 60 ml/min. G2 showed a significant increase in CRP values at 48 h post-race vs baseline compared to G1 (P < 0.05), with over 5 mg/L (6.8–15.2) in 92% of the runners, and in CK values with over 215 U/L (282–1,882) at 48 h post-race in 100% of the runners. By BIVA, the 95% confidence ellipses of G2 showed shorter bioimpedance vectors than G1, with a noticeable minor Xc/H (P < 0.01), indicating an expansion on extracellular water and inflammation. The runners with 48 h post-race Xc/H values ≤30.5 Ω, with a decrease from −3 to −12% with respect to the Xc/H value at 24 h pre-race, indicated AKI stage 1 with 85.7% sensitivity and 91.7% specificity, with a direct correlation between AKI stage 1 with greater CRP values at 48 h post-race and bioimpedance vector displacement, but not with CK values at 48 h post-race.Conclusion: Through this data collection, it was evidenced that a transient reduction in renal function is more related to inflammatory factors than muscle damage. The BIVA method along with serum biomarkers could be used to follow up the kidney function in runners.

Nutritional status and body composition by bioelectrical impedance vector analysis: A cross sectional study in mild cognitive impairment and Alzheimer's disease.

AimsAnalysis of nutritional status and body composition in Alzheimer’s disease (AD) and Mild Cognitive Impairment (MCI).MethodsA cross-sectional study was performed in a University-Hospital setting, recruiting 59 patients with AD, 34 subjects with MCI and 58 elderly healthy controls (HC). Nutritional status was assessed by anthropometric parameters (body mass index; calf, upper arm and waist circumferences), Mini Nutritional Assessment (MNA) and body composition by bioelectrical impedance vector analysis (BIVA). Variables were analyzed by analysis of variance and subjects were grouped by cognitive status and gender.ResultsSociodemographic variables did not differ among the three groups (AD, MCI and HC), except for females’ age, which was therefore used as covariate in a general linear multivariate model. MNA score was significantly lower in AD patients than in HC; MCI subjects achieved intermediate scores. AD patients (both sexes) had significantly (p<0.05) higher height-normalized impedance values and lower phase angles (body cell mass) compared with HC; a higher ratio of impedance to height was found in men with MCI with respect to HC. With BIVA method, MCI subjects showed a significant displacement on the RXc graph on the right side indicating lower soft tissues (Hotelling’s T2 test: men = 10.6; women = 7.9;p < 0,05) just like AD patients (Hotelling’s T2 test: men = 18.2; women = 16.9; p<0,001).ConclusionBioelectrical parameters significantly differ from MCI and AD to HC; MCI showed an intermediate pattern between AD and HC. Longitudinal studies are required to investigate if BIVA could reflect early AD-changes in body composition in subjects with MCI.

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

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). 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) <18.5kg/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. 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. 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.

Qualitative body composition of cyclists: bioimpedance vector analysis discriminates different categories of cyclists

Introduction: Bioelectrical impedance vector analysis (BIVA) and the phase-angle (PA), derived from bioelectrical impedance raw values (i.e., resistance, R, and reactance, Xc) allow qualitative and descriptive assessments of body composition and hydration status, independent of prediction equations, body weight and body composition models [3,4,5]. Bioelectrical impedance reference values for the healthy normal population, soccer players [6] and several clinical settings are well established [1,2], but are lacking for male cyclists. Therefore, the aim of the present study was to obtain reference bioelectrical impedance data characterizing professional, elite, junior, and amateur male road cyclists.  Methods: The study included 102 male professional riders (age: 25.6±4.7 yr, height: 178.3±5.9 cm, weight: 68.5±5.9 kg), 225 male amateur riders (age: 39±2 yr, height: 176.1±6.4 cm, weight: 71.1±9.5 kg), 46 male junior cyclists (age: 16.9±1.2 yr, height 176.60±5.94 cm, weight 65.62±7.27 kg) and 69 male elite road cyclists (age: 21±2.9 yr, height: 178.2±5.7 cm, weight: 69.03±7.6 kg). The controls were represented by normal values of healthy male Italian population (age: 48±17 yr, height: 170.4±8 cm, weight: 72.6±11.5 kg) [2]. Professional cyclists were classified into 3 groups according to their team role (sprinter, n=16; climber, n=35; all-rounder, n=51), whereas the juniors, amateurs and elite cyclists were all considered all-rounder. Whole-body impedance measurements (BIA- 101 Anniversary AKERN/RJL-Systems) were performed during the peak performance period of the cyclists. All measurements were obtained in compliance with the manufacturer’s guidelines and analyzed according to the BIVA method [1]. BIVA, compared to the estimated fat and fat-free masses with conventional BIA, does not use regression prediction equations, and was shown to adequately display differences in hydration and soft tissue mass in healthy people and athletes [7]. Furthermore, BIVA allows establishing population- specific norms (50, 75 and 95% tolerance ellipses).  Results: Compared to the amateur cyclists and the normal population, the group vector and the tolerance ellipses of the professional cyclists was displaced to the upper left (p<0.001) as well as the comparison of the amateurs and juniors (p<0.001), amateurs and elite cyclists (p<0.001) (fig. 1). Also, all categories showed a shift to the upper left in comparison of controls. Comparisons of professional cyclists to amateurs and elite cyclists to amateurs showed a higher phase-angle (7.1°±0.1 vs 6.5°±0.8 (p<0.001) and 7.0°±0.7 vs 6.5°±0 (p<0.001), respectively). Significant differences in vector position were found between sprinters and climbers (p<0.05) and between allrounders and climbers (p<0.02) (fig. 2).  Conclusion: The main finding of the present study is that road cyclists in general and specialists have specific bioimpedance values compared to non-cyclists. Muscle mass and function, as indicated by the left shifted vector and the phase-angle, increased with increasing performance level. The specific tolerance ellipses of the professionals might be used for classifying individual vectors of professional cyclists and to define target regions for lower level cyclists.

Reference values of the bioimpedance vector components in a Caribbean population

Summary Background & aims Application of bioelectrical impedance vector analysis (BIVA) requires comparison of an impedance vector to reference intervals derived from healthy subjects. The aim of this work is to obtain reference nomograms of bioimpedance vectors from healthy subjects living in Santiago de Cuba. Methods A sample of 4030 healthy people, ages 2–80 y, was measured using a tetra-polar whole-body bioimpedance analyzer at 50 kHz. BIVA method uses the 50, 75 and 95% confidence ellipses of reference populations to classify individual and group vectors. Results The 95% confidence ellipses derived among boys and girls (2–12 y) were similar (P > 0.05) with significant gender differences (P 60 y we also observed a phase downfall, possibly due to the reduction of mass and structure, by sarcopenia. Conclusions Reference ellipses are provided, distributed in six sets resulting in age separation intervals (not in gender) for children from 2 to 12 y; two gender specific reference ellipses for teenagers in the range of 13–16 y, for adults from 17 to 59 y and for elderly people from 60 to 80 y.

Bioelectrical impedance and strength measurements in patients with heart failure: comparison with functional class

Objective Patients with chronic heart failure (HF) develop important changes in body composition. Nevertheless, the usual methods of body composition assessment can be misleading in patients with HF because tissue hydration is altered. Bioelectrical impedance vector analysis (BIVA) works without making any assumption about constant soft tissue hydration. In this study, patients with HF and systolic dysfunction (HFS) and preserved systolic function (HFPSF) underwent a body composition evaluation by the BIVA method; the comparison was done between New York Heart Association (NYHA) functional classes I–II and III–IV. Methods We studied 243 patients with HF, 140 (101 in NYHA I–II and 39 in III–IV) with HFS and 103 (67 in NYHA I–II and 36 in II–IV) with HFPSF. Whole-body bioelectrical impedance was measured using BodyStat QuadScan 4000, which is tetrapolar and multiple-frequency equipment. Results In both HF categories, reactance and phase angle were significantly lower, the impedance ratio of 200 kHz to that at 5 kHz was higher, and had significantly shorter and downsloping impedance vector in the NYHA III–IV group compared with the NYHA I–II group by gender. Conclusion Bioelectrical impedance analysis allows an easier evaluation of body composition and this might be particularly useful to stratify the severity of HF.

Bioelectrical impedance vector analysis in haemodialysis patients: relation between oedema and mortality

In this work, bioelectrical impedance vector analysis (BIVA) method is used in a sample of haemodialysis patients in stable (without oedema) and critical (hyperhydrated and malnutrition) states, in order to establish the relation between hyperhydration (oedema) and mortality. The measurements obtained were single frequency (50 kHz), tetrapolar (hand–foot) complex impedance measurements (vector components are: resistance R and reactance Xc). The impedance components were standardized by the height H of the subjects, (R/H and Xc/H) to obtain de impedance vector Z/H, that is represented in the RXc plot (abscise R/H, ordinate Xc/H). Measurements were performed on a sample of 74 patients (30 men and 44 women, 18–70 year, body mass index (BMI), 19–30 kg m−2) at the Saturnino Lora University Hospital in Santiago de Cuba. The 46 stable patients comprised 28 men and 18 women; the 28 critical patients 16 men and 12 women. The reference population consisted of 1196 healthy adult subjects living in Santiago de Cuba (689 men and 507 women, 18–70 year, BMI 19–30 kg m−2). We used the RXc plot with the BIVA method to characterize the reference population using the 50%, 75% and 95% tolerance ellipses. Student's t-test and Hotelling's T2-test were used to analyse the separation of groups obtained by means of clinical diagnosis and those obtained by BIVA. We obtained a significant difference (P < 0.05) in R/H, Xc/H and phase angle (PA) in men as in women between the location of Z/H vectors in the RXc graph and the separation made by the doctors between stable and critical patients. Critical (hyperhydrated) patients were located below the inferior pole of the 75% tolerance ellipse, whereas stable patients were within the tolerance ellipses. Some cases classified as stable by the clinic were classified as hyperhydrated by BIVA with 100% sensitivity and 48% specificity. In conclusion, the BIVA method could be used to classify patients by hydration state and to predict survival. Advantages of the method are its simplicity, objectivity and that it does not require the definition of patient dry weight.