The Biagram Vector: A Graphical Relation between Reactance and Phase Angle Measured by Bioelectrical Analysis in Infants

Abstract

Background: Biagram vector is derived by plotting direct measurements of reactance and phase angle from the analyzer, which are not dependent on anthropometric characteristics of the subject and it can be considered an emerging method for evaluating the nutritional status in clinical practice. Aim: To calculate and plot the Biagram vector in a sample of healthy infants in their first year of life. Methods: 174 healthy infants (99 male, 75 female) aged under 1 year, born at full term and adequate for gestational age, were enrolled in a cross-sectional study. The sample was divided into three age groups: 0–3.99 months (group A), 4–7.99 months (group B), and 8–11.99 months (group C). Bioelectric impedance analysis (BIA) was performed by a tetrapolar single frequence phase-sensitive impedance analyzer (STA/BIA; Akern Srl, Firenze, Italy). Results: Biagram vector showed an increasing trend (p < 0.05) in the first year of life (group A: 27.9 ± 12.6; group B: 32.1 ± 9.7; group C: 37.2 ± 9.5). Females showed Biagram vector values significantly higher than males in group A (34.7 ± 15.0 vs. 24.0 ± 9.1; p < 0.05). 95% confidence ellipses of Biagram vector for each age group were calculated and plotted and a comparison of our results with published data calculated in older children was conducted. Conclusion: The bivariate analysis of BIA measurements, plotted as a vector in relation to the age, showed an increasing trend with a higher gain rate under 1 year with respect to the following age periods. These data could reflect the variation of body composition in the first years of life and could be of interest to assess the nutritional status for clinical practice.

Bioelectrical impedance analysis in clinical practice: a new perspective on its use beyond body composition equations

“…Another PA presentation is in biagram vector, which is derived from the graphical plotting of capacitive reactance and PA. Savino et al [14 ] studied 174 infants under one year, plotting the biagram vector for groups from each 4 months of life. There was an increasing trend from the younger to the older group, explained by the variation of 312 Pharmaceutical aspects, devices and techniques In conclusion, PA differs between the sexes and decreases with ageing, like other biological parameters.…”

Phase Angle From Bioelectrical Impedance Analysis: Population Reference Values by Age, Sex, and Body Mass Index

“…Results are also not biased by the choice of regression equation, the accuracy of the criterion method, or the selection criteria of the reference population. Today, many publications focus on the use of resistance (R) and reactance (Xc) standardized by body height in a bivariate vector analysis (BIVA) [1][2][3][4][5][6][7][8][9] and reference values from different populations stratified according to ethnic, age, and body mass index (BMI) groups are available. 6,7,10 Clinically, the most established impedance parameter is, however, the phase angle for the diagnosis of malnutrition and clinical prognosis, both associated with changes in cellular membrane integrity and alterations in fluid balance.…”

Metrological characterization of instruments for body impedance analysis

“…Consequently, Re is the maximum value of resistance. The relationship between the capacitance 𝑋 𝑐 and the total resistance R of a body can be expressed by a phase angle φ [12]. Therefore, the resulting phasor ranging from Ri and Re describes an arc segment as shown in Figure 2 and all the measured values would lie below it.…”