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Published on: August 17, 2022
Association of electrical bioimpedance vectors with the nutritional classification of vulnerable multiethnic children
Taisa Lisboa Montagner Gomes1, Maria Virginia Marques Peixoto2, Zina Maria Almeida de Azevedo3
1Department of Education and Research, Instituto Federal de Educação, Ciência e Tecnologia do Maranhão, São Luís, Brazil.
Insights
Bioelectrical impedance vector analysis (BIVA) effectively monitors children's nutritional status, even with obesity. This method shows promise for assessing body composition where traditional measurements are challenging.
Area of Science:
- Pediatric Nutrition
- Body Composition Analysis
- Biomedical Engineering
Background:
- Childhood growth and body composition monitoring are crucial for identifying health and nutrition issues.
- Bioelectrical impedance vector analysis (BIVA) is an effective indicator of nutritional status.
- Assessing nutritional status in vulnerable children, including those with obesity, requires reliable methods.
Purpose of the Study:
- To measure bioimpedance vectors in a multiethnic sample of children aged 1-4 years.
- To evaluate the utility of BIVA for classifying nutritional status in children.
- To assess BIVA's effectiveness in identifying deviations in nutritional status, particularly in obese children.
Main Methods:
- A cross-sectional study involving 321 children from public daycare centers.
- Utilized tetrapolar analysis (50 kHz) and the RXc graph method for bioelectrical impedance analysis.
- Plotted 95%, 75%, and 50% tolerance ellipses by age group and calculated Z-scores to create reference ellipses.
Main Results:
- Mean impedance vectors showed increased reactance and decreased resistance with age.
- Obese children exhibited individual vectors outside the 95% ellipse (11.1%-18.75%), exceeding the expected 5%.
- Current obesity criteria (WHZ, WAZ, BMIZ) may not accurately differentiate fat from lean mass, impacting BIVA interpretation.
Conclusions:
- BIVA reflects distinct bioelectric patterns in obese children.
- BIVA, using tolerance ellipses, is a promising tool for nutritional status monitoring when body composition measurements are difficult.
- Accurate BIVA application for nutritional assessment requires obesity criteria based on fat mass rather than lean mass.
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.
Methods:
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.
Results:
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.
Conclusion:
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.
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