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Bioelectrical impedance vector distribution in the first year of life
Francesco Savino1, Giulia Grasso, Francesco Cresi
1Department of Pediatrics, University of Turin, Regina Margherita Children Hospital, Piazza Polonia, 94-10126 Turin, Italy. savino@pediatria.unito.it
Insights
This study established bioelectrical impedance vector distribution reference values for healthy infants up to one year old. Findings show no significant vector migration during this developmental period, providing crucial data for infant health assessments.
Area of Science:
- Pediatric Physiology
- Bioelectrical Impedance Analysis
Background:
- Bioelectrical impedance vector analysis (BIVA) is a valuable tool for assessing body composition.
- Normative data for BIVA in healthy infants during the first year of life is lacking in current literature.
Purpose of the Study:
- To assess the bioelectrical impedance vector distribution in healthy Caucasian infants during their first year of life.
- To establish reference ranges for impedance vectors in this population.
Main Methods:
- A cross-sectional study involving 153 healthy Caucasian infants (<1 year).
- Whole-body tetrapolar bioelectrical impedance measurements (resistance and reactance) using a single-frequency analyzer.
- Statistical analysis included calculating bivariate 95% confidence limits and tolerance intervals for impedance vectors, stratified by sex and age groups (0-3.99 mo, 4-7.99 mo, 8-11.99 mo).
Main Results:
- Raw resistance and reactance values showed fluctuations during infancy.
- Overlapping 95% confidence ellipses for mean vectors across age groups and sexes indicated no significant vector migration in the first year of life.
- Bivariate tolerance ellipses (95%, 75%, 50%) for individual vector measurements were calculated.
Conclusions:
- This study provides the first estimate of mean impedance vectors in healthy infants during the first year of life.
- Reference bivariate tolerance ellipses were calculated for individual vector measurements.
- The findings establish a baseline for BIVA in infant health monitoring and research.
Objective:
We assessed the bioelectrical impedance vector distribution in a sample of healthy infants in the first year of life, which is not available in literature.
Methods:
The study was conducted as a cross-sectional study in 153 healthy Caucasian infants (90 male and 63 female) younger than 1 y, born at full term, adequate for gestational age, free from chronic diseases or growth problems, and not feverish. Z scores for weight, length, cranial circumference, and body mass index for the study population were within the range of +/-1.5 standard deviations according to the Euro-Growth Study references. Concurrent anthropometrics (weight, length, and cranial circumference), body mass index, and bioelectrical impedance (resistance and reactance) measurements were made by the same operator. Whole-body (hand to foot) tetrapolar measurements were performed with a single-frequency (50 kHz), phase-sensitive impedance analyzer. The study population was subdivided into three classes of age for statistical analysis: 0 to 3.99 mo, 4 to 7.99 mo, and 8 to 11.99 mo. Using the bivariate normal distribution of resistance and reactance components standardized by the infant's length, the bivariate 95% confidence limits for the mean impedance vector separated by sex and age groups were calculated and plotted. Further, the bivariate 95%, 75%, and 50% tolerance intervals for individual vector measurements in the first year of life were plotted.
Results:
Resistance and reactance values often fluctuated during the first year of life, particularly as raw measurements (without normalization by subject's length). However, 95% confidence ellipses of mean vectors from the three age groups overlapped each other, as did confidence ellipses by sex for each age class, indicating no significant vector migration during the first year of life.
Conclusions:
We obtained an estimate of mean impedance vector in a sample of healthy infants in the first year of life and calculated the bivariate values for an individual vector (95%, 75%, and 50% tolerance ellipses).
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