Bioelectrical impedance vector analysis (BIVA) in stable preterm newborns

Abstract

Objective: To observe the behavior of the plotted vectors on the RXc (R -resistance -and Xc -reactance corrected for body height/ length) graph through bioelectrical impedance analysis (BIVA) and phase angle (PA) values in stable premature infants, considering the hypothesis that preterm infants present vector behavior on BIVA suggestive of less total body water and soft tissues, compared to reference data for term infants.Methods: Cross-sectional study, including preterm neonates of both genders, in-patients admitted to an intermediate care unit at a tertiary care hospital. Data on delivery, diet and bioelectrical impedance (800 mA, 50 kHz) were collected. The graphs and vector analysis were performed with the BIVA software.Results: A total of 108 preterm infants were studied, separated according to age (< 7 days and ≥ 7 days). Most of the premature babies were without the normal range (above the 95% tolerance intervals) existing in literature for term newborn infants and there was a tendency to dispersion of the points in the upper right quadrant, RXc plan. The PA was 4.92° (±2.18) for newborns < 7 days and 4.34° (±2.37) for newborns ≥ 7 days. Conclusion:Premature infants behave similarly in terms of BIVA and most of them have less absolute body water, presenting less fat free mass and fat mass in absolute values, compared to term newborn infants.J Pediatr (Rio J). 2012;88(3):253-8: Premature infant, newborn infant, electrical impedance, body composition. ResumoObjetivo: Observar o comportamento dos vetores ponteados no gráfico de resistência e de reactância corrigidos pelo comprimento corporal (RXc) através da análise vetorial de impedância bioelétrica (BIVA) e os valores de ângulo de fase (AF) em recém-nascidos (RNs) pré-termo estáveis, considerando a hipótese que o RN pré-termo apresenta o seu comportamento vetorial na BIVA sugestivo de menor quantidade de água e de tecidos moles corporais, comparativamente à referência do RN a termo.Métodos: Foi realizado estudo de corte transversal em RNs pré-termo, de ambos os sexos, que se encontravam em uma unidade de cuidados intermediários de um hospital terciário. Coletaram-se dados relacionados ao nascimento e à alimentação, bem como dados de bioimpedância elétrica (800 mA, 50 kHz). Os gráficos e as análises vetoriais foram realizados através do BIVA software.Resultados: Um total de 108 RNs pré-termo foram estudados, separados por faixa etária (< 7 dias e ≥ 7 dias). A maioria dos RNs pré-termo encontrou-se fora da normalidade (acima dos intervalos de tolerância de 95%) existentes na literatura para RNs a termo, e observou-se uma tendência para a dispersão dos pontos no quadrante superior direito no gráfico RXc. O AF dos RNs < 7 dias foi de 4,92° (±2,18), e a dos RNs ≥ 7 dias, de 4,34° (±2,37). Conclusão:Os RNs pré-termo se comportam de maneira semelhante entre si. A maioria deles possui menor quantidade absoluta de água corporal e apresenta menor quantidade tanto de massa livre de gordura quanto de massa gorda, em valores absolutos, quando comparados com os...

Bioelectrical Impedance Vector Analysis and Phase Angle on Different Oral Zinc Supplementation in Eutrophic Children: Randomized Triple-Blind Study

“…R reflects the quantity of intra- and extracellular fluids, and Xc, the quantity of cell mass, the structure and cell membranes functionality. From these vectors, it is possible to calculate the phase angle (PA) and perform the bioelectrical impedance vector analysis (BIVA) [2,3].…”

“…BIVA is useful for clinical purposes because it detects changes in hydration or body composition, as demonstrated by Carrasco-Marginet et al [9] and Koury et al [10]. Using BIVA, it is possible to evaluate the patient by direct vector impedance measurements because this method does not depend on equations or models; it is a graphical method with R and Xc corrected for height, which can generate three analyses: individual, follow-up, and groups [3].…”

Bioelectrical impedance vector values in a Spanish healthy newborn population for nutritional assessment

“…The higher the water and electrolyte content of the tissues, the more they will allow passage of the current. However, the conventional BIA approach makes a series of assumptions about the density and hydration of the fat-free mass or certain body geometry proportions, which are not met in newborns or during the first months of life (Margutti et al, 2012). In addition, interpretation of the analysis of the conventional BIA approach requires the application of prediction equations to transform the electrical variables (resistance [R] and reactance [Xc]) into variables of body composition (body water, fat-free mass, and fat mass).…”

Bioelectrical impedance vector analysis and phase angle in boys with Duchenne muscular dystrophy

“…Thus, this parameter is useful for assessing disease severity as well as patient prognosis in different clinical settings. For these reasons, PA seems to be superior to other nutritional, anthropometric, and serum parameters (13).…”