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Updated: Apr 14, 2026
Evaluation of Fluid Overload by Bioelectrical Impedance Vectorial Analysis
Published on: August 17, 2022
Normal values for segmental bioimpedance spectroscopy in pediatric patients
Maria Laura Avila1, Leigh C Ward2, Brian M Feldman3
1Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
Insights
Bioimpedance spectroscopy (BIS) establishes normal fluid volume ranges for children's limbs. Limb circumference measurements may not accurately reflect fluid changes, indicating BIS is a more reliable method for assessing localized edema in most pediatric cases.
Area of Science:
- Pediatric Medicine
- Biomedical Engineering
- Diagnostic Techniques
Background:
- Localized limb edema is a common clinical sign in pediatric conditions like post-thrombotic syndrome and lymphedema.
- Current methods for quantifying pediatric limb edema, such as circumference measurements, include non-fluid mass, potentially limiting accuracy.
- Bioimpedance spectroscopy (BIS) offers a non-invasive method to assess fluid volume in body segments.
Purpose of the Study:
- To establish normal ranges for segmental bioimpedance spectroscopy (BIS) measurements in the arms and legs of healthy children.
- To determine normal ranges for the difference in arm and ankle circumferences in children.
- To investigate the influence of handedness and the correlation between BIS and circumference measurements for assessing limb edema.
Main Methods:
- Recruitment of 223 healthy children aged 1-18 years.
- Measurement of extracellular and intracellular fluid ratios using a bioimpedance spectrometer.
- Determination of arm and ankle circumferences using a Gulick II tape.
Main Results:
- Normal values for arm and leg BIS measurements and circumference differences were established for different pediatric age categories.
- Handedness did not significantly influence the measurements.
- A significant correlation was observed between the extracellular impedance ratio and circumference difference in the arms of teenagers only.
Conclusions:
- Normal BIS ranges for pediatric arms and legs, and circumference differences were successfully determined.
- The study suggests that limb circumference measurements may include non-fluid components, potentially limiting their utility in detecting localized edema in children.
- BIS emerges as a more sensitive technique for evaluating fluid volume and localized edema in pediatric limbs across most age groups.
Introduction:
Localized limb edema is a clinically relevant sign in diseases such as post-thrombotic syndrome and lymphedema. Quantitative evaluation of localized edema in children is mainly done by measuring the absolute difference in limb circumference, which includes fat and fat-free mass. Bioimpedance spectroscopy (BIS) provides information on the fluid volume of a body segment. Our objective was to determine normal ranges for segmental (arm and leg) BIS measurements in healthy children. Additionally, we determined the normal ranges for the difference in arm and ankle circumference and explored the influence of handedness and the correlation between techniques.
Methods:
Healthy children aged 1-18 years were recruited. The ratio of extracellular fluid content between contralateral limbs (estimated as the inter-arm and inter-leg extracellular impedance ratio), and the ratio of extracellular to intracellular fluid content for each limb (estimated as the intracellular to extracellular impedance ratio) were determined with a bioimpedance spectrometer. Arm and ankle circumference was determined with a Gulick II tape.
Results:
We recruited 223 healthy children (48 infants, 54 preschoolers, 66 school-aged children, and 55 teenagers). Normal values for arm and leg BIS measurements, and for the difference in arm and ankle circumference were estimated for each age category. No influence of handedness was found. We found a statistically significant correlation between extracellular impedance ratio and circumference difference for arms among teenagers.
Conclusion:
We determined normal BIS ranges for arms and legs and for the difference in circumference between arms and between ankles in children. There was no statistically significant correlation between extracellular impedance ratio and difference in circumference, except in the case of arms in adolescents. This may indicate that limb circumference measures quantities other than fluid, challenging the adequacy of this technique to determine the presence of localized edema in most age groups.
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