Calf Bioimpedance Analysis: A Novel Approach for Evaluating Hydration Status in Pediatric Dialysis Patients Under High Dialysate Sodium
DOI:
https://doi.org/10.61186/Keywords:
Calf bioimpedance, Hydration status, Hemodialysis, Pediatric nephrology, Sodium balance, Fluid monitoring, UltrafiltrationAbstract
Introduction. Assessment of hydration status in pediatric hemodialysis is complicated by dynamic fluid shifts and sodium variability. Conventional methods such as clinical evaluation and whole-body bioimpedance analysis (BIA) lack precision for individual-level monitoring. This study introduces a calf impedance ratio (ΔZ₁₅ₖₕ / ΔZ₁₅₀ₖₕ) to classify fluid responses and evaluate the impact of high dialysate sodium (143 mEq/L) on fluid dynamics and blood pressure.
Methods. A cross-sectional study was conducted involving 14 children aged 5–12 years undergoing maintenance hemodialysis. Impedance was measured pre- and post-dialysis at two frequencies using a custom-built device. The raw impedance changes were analyzed without conversion to fluid volumes, allowing for classification into three physiological response groups based on the impedance ratio.Results. Three distinct physiological profiles emerged. Group1 (ΔZΔZ150kh15kh > 1) showed effective extracellular fluid removal with stable hemodynamics. Group 2 (ratio between 0 and 1) reflected minimal Extracellular Water (ECW) ECW changes, potentially due to sodium-driven redistribution, with additional influence from sodium-enhanced tissue conductivity. Group 3 (ΔZ₁₅ₖₕ < 0) exhibited paradoxical impedance decreases despite fluid removal,along with sodium increase and blood pressure elevation. ΔZ₁₅ₖₕpositively correlated with ΔBP-sys (r = 0.650, P = .012). Conclusion. The impedance ratio (ΔZΔZ150kh15kh ) provides a sensitive index for classifying fluid responses and identifying sodium-related effects in pediatric hemodialysis. It may support individualized dialysis prescriptions by guiding adjustments in ultrafiltration and dialysate sodium to improve hemodynamic stability and fluid balance.
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