Abstract:
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BACKGROUND/OBJECTIVES: Bioelectrical impedance vector analysis (BIVA) is increasingly used in clinical research to assess soft
Q2 tissue hydration. It is known that physical characteristics of electrodes, such as low intrinsic impedance, low electrode/skin contact
impedance and type of gel, affect the reliability of noninvasive bioimpedance assessments. The aim of this study was to determine
the effect of intrinsic impedance of electrode on the bioimpedance vector displacement in RXc graph.
SUBJECTS/METHODS: The intrinsic impedance is measured in nine pregelled disposable Ag/AgCl electrodes usually used for
bioimpedance measures. The BIVA method is performed on 35 healthy volunteers using a 50 kHz phase-sensitive bioimpedance
analyzer (BIA 101 Anniversary) with the lowest intrinsic impedance electrode and highest. The individual bioimpedance vector is
plotted on the bivariate normal interval of reference population. The differences in the mean bioimpedance vectors obtained with
each electrode are plotted, with their 95% confidence ellipses, on the dRXc graph. The paired one-sample Hotelling's T2
-test is used
to compare the differences of the mean bioimpedance vectors.
RESULTS: We found large variability in intrinsic resistance (11–665 O) and reactance (0.25–2.5 O) values of the electrodes analyzed
and significant displacement (Po0.05) of bioimpedance vector positions in healthy adults according to the paired one-sample
Hotelling's T2
-test.
CONCLUSIONS: A robust study of all physical characteristics of commercial Ag/AgCl electrodes is necessary to reach consensus on
pregelled Ag/AgCl electrodes valid for bioimpedance measurement. This information will enable BIVA users to avoid systemic errors
when performing BIVA assessments, specifically when these measurements are used for clinical interpretations. |