Department of Education and Research, Instituto Federal de Educação, Ciência e Tecnologia do Maranhão, São Luís, Brazil.
Analytical Methods Laboratory, Research Department, Instituto Fernandes Figueira, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil.
Clin Nutr ESPEN. 2021 Dec;46:453-458. doi: 10.1016/j.clnesp.2021.09.011. Epub 2021 Sep 22.
BACKGROUND & AIMS: Monitoring growth and body composition in childhood is vital for early detection of health and nutrition problems during child development. The bioelectrical impedance vector analysis (BIVA) revealed its effectiveness as an indicator of nutritional status. This study aimed to measure the bioimpedance vectors of a sample of multiethnic children and evaluate the utility of BIVA for the classification of the nutritional status in a group of children with greater vulnerability, including in the presence of obesity.
This is a cross-sectional study that analyzed the bioelectrical impedance of a sample of 321 children from public daycare centers, aged 1-4 years, using the RXc graph method (tetrapolar analysis at 50 kHz frequency). The 95%, 75%, and 50% tolerance ellipses were plotted by age group. The Z-scores of bioimpedance parameters (Xc/H-Z and R/H-Z) were calculated regarding age, which were used to build reference tolerance ellipses for a single group, regardless of age. Such ellipses were evaluated for their ability to recognize the pattern and classify the deviations, using individual vectors of obese children.
The mean impedance vectors showed progressively higher reactances and lower resistances with age. In the group of obese children, the individual vectors located outside the 95% baseline tolerance ellipse were 12.5%, 18.75%, and 11.1% of the cases for the WHZ, WAZ, and BMIZ criteria, respectively, all above the expected 5%, but much below expectations. This may be a problem with the obesity criteria used, as WHZ, WAZ, and BMIZ do not differentiate fat from lean mass.
Bioimpedance vector analysis reflects differences in the bioelectric patterns of children classified as obese. Provided the obesity criteria are constructed based on fat measurements, rather than lean mass, the use of tolerance ellipses in the BIVA chart is promising as a tool for monitoring nutritional status where measuring body composition is difficult, because constant tissue hydration cannot be assumed.
监测儿童期的生长和身体成分对于在儿童发育过程中早期发现健康和营养问题至关重要。生物电阻抗向量分析（BIVA）已被证明是一种评估营养状况的有效指标。本研究旨在测量一组多民族儿童的生物电阻抗向量，并评估 BIVA 在分类营养状况方面的效用，包括在存在肥胖的情况下。
这是一项横断面研究，分析了来自公立日托中心的 321 名 1-4 岁儿童的生物电阻抗，使用 RXc 图法（50 kHz 频率的四极分析）。根据年龄绘制 95%、75%和 50%的耐受椭圆。根据年龄计算生物电阻抗参数（Xc/H-Z 和 R/H-Z）的 Z 分数，用于构建与年龄无关的单个组别的参考耐受椭圆。使用肥胖儿童的个体向量评估这些椭圆识别模式和分类偏差的能力。
平均阻抗向量随年龄增长呈现出更高的电抗和更低的电阻。在肥胖儿童组中，WHZ、WAZ 和 BMIZ 标准的个体向量分别有 12.5%、18.75%和 11.1%位于 95%基线耐受椭圆之外，均高于预期的 5%，但远低于预期。这可能是使用的肥胖标准存在问题，因为 WHZ、WAZ 和 BMIZ 不能区分脂肪和瘦体重。
生物电阻抗向量分析反映了肥胖儿童分类的生物电模式的差异。如果肥胖标准基于脂肪测量而不是瘦体重构建，则 BIVA 图表中的耐受椭圆的使用具有作为监测营养状况的工具的潜力，因为不能假设组织保持恒定的水合作用，在这种情况下测量身体成分较为困难。
