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The feasibility of using compression bioimpedance measurements to quantify peripheral edema Cover

The feasibility of using compression bioimpedance measurements to quantify peripheral edema

Journal of Electrical Bioimpedance
Volume 5 (2014): Issue 1 (January 2014)
By: Leo Koziol,  John J. Pitre,  Joseph L. Bull,  Robert E. Dodde,  Grant Kruger,  Alan Vollmer and  William F. Weitzel  
Open Access
|Dec 2014

Figures & Tables

Fig.1

Conventional segmental BIS measurement during a dialysis session, where the measurement is across the lower calf of the patient.
Conventional segmental BIS measurement during a dialysis session, where the measurement is across the lower calf of the patient.

Fig.2

Simple model describing the relationship between resistance and strain in a homogeneous material under compression.
Simple model describing the relationship between resistance and strain in a homogeneous material under compression.

Fig.3

Schematic diagram of the compression BIS system used in this study.
Schematic diagram of the compression BIS system used in this study.

Fig.4

Schematic of the BIS circuitry used in this study.
Schematic of the BIS circuitry used in this study.

Fig.5

Test circuit used to validate the BIS circuitry and generate a Cole type plot [32, 33, 34]. The circuit consisted of two 1% 2000 Ω resistors and an 11 nF capacitor (1% measured tolerance). The impedance of the test circuit was measured for different current source input frequencies and compared to the theoretical model.
Test circuit used to validate the BIS circuitry and generate a Cole type plot [32, 33, 34]. The circuit consisted of two 1% 2000 Ω resistors and an 11 nF capacitor (1% measured tolerance). The impedance of the test circuit was measured for different current source input frequencies and compared to the theoretical model.

Fig.6

Close-up view of the 3mm x 3mm platinum leaf probes used in this study.
Close-up view of the 3mm x 3mm platinum leaf probes used in this study.

Fig.7

Detailed view of the experimental setup used during impedance measurements for both quasi-static and dynamic loadings.
Detailed view of the experimental setup used during impedance measurements for both quasi-static and dynamic loadings.

Fig.8

Phase shift measured by the BIS circuitry for a single 2000 resistor test circuit. We observed no phase shift for the frequency range of 500 HZ to 20 KHZ. Large phase shifts occurred for frequencies above 100 KHz.
Phase shift measured by the BIS circuitry for a single 2000 resistor test circuit. We observed no phase shift for the frequency range of 500 HZ to 20 KHZ. Large phase shifts occurred for frequencies above 100 KHz.

Fig.9

Plot of the measured real and imaginary components of the complex impedance for the test circuit shown in Fig. 5. The experimental data ( • ) showed reasonable agreement (within 25%) of the expected theoretical behavior ( ─ ) (Eq. 3 and 4).
Plot of the measured real and imaginary components of the complex impedance for the test circuit shown in Fig. 5. The experimental data ( • ) showed reasonable agreement (within 25%) of the expected theoretical behavior ( ─ ) (Eq. 3 and 4).

Fig.10

Resistance of 0.9% saline solution diluted to various fractions of the original concentration (0.1552 mol/L solution of NaCl in water). Measurements were performed with the BIS circuitry and platinum leaf probes. The electronics exhibit a flat frequency response across the entire spectrum of chosen operating frequencies.
Resistance of 0.9% saline solution diluted to various fractions of the original concentration (0.1552 mol/L solution of NaCl in water). Measurements were performed with the BIS circuitry and platinum leaf probes. The electronics exhibit a flat frequency response across the entire spectrum of chosen operating frequencies.

Fig.11

Percent impedance change of tofu blocks under quasistatic loading conditions for a 10 kHz input frequency. As the tofu is compressed, the impedance increases monotonically. Larger variations in the measured impedance are observed at higher strains. Error bars denote ± one standard deviation from the mean (n = 13).
Percent impedance change of tofu blocks under quasistatic loading conditions for a 10 kHz input frequency. As the tofu is compressed, the impedance increases monotonically. Larger variations in the measured impedance are observed at higher strains. Error bars denote ± one standard deviation from the mean (n = 13).

Fig.12

Stress-relaxation response of tofu subjected to a constant strain of 33%. After an initial spike in internal stress, fluid movement within the tofu allows the stress field to approach a steady state. The results of individual experiments (gray lines), the ensemble mean (black line), ensemble envelope (light gray shaded), and ± one standard deviation from the mean (dark gray shaded) are shown (n = 13).
Stress-relaxation response of tofu subjected to a constant strain of 33%. After an initial spike in internal stress, fluid movement within the tofu allows the stress field to approach a steady state. The results of individual experiments (gray lines), the ensemble mean (black line), ensemble envelope (light gray shaded), and ± one standard deviation from the mean (dark gray shaded) are shown (n = 13).

Fig.13

Normalized compression BIS response of tofu subjected to a constant strain of 33%. The impedance rises rapidly during the initial compression then approaches a steady state value. The results of individual experiments (gray lines), the ensemble mean (black line), ensemble envelope (light gray shaded), and ± one standard deviation from the mean (dark gray shaded) are shown (n = 13).
Normalized compression BIS response of tofu subjected to a constant strain of 33%. The impedance rises rapidly during the initial compression then approaches a steady state value. The results of individual experiments (gray lines), the ensemble mean (black line), ensemble envelope (light gray shaded), and ± one standard deviation from the mean (dark gray shaded) are shown (n = 13).

Fig.14

Parametric plot of the stress-relaxation and normalized compression BIS responses of tofu subjected to a constant strain of 33%. The results of individual experiments (gray lines), the ensemble mean (black line), and ± one standard deviation from the mean (dark gray shaded) are shown (n = 13).
Parametric plot of the stress-relaxation and normalized compression BIS responses of tofu subjected to a constant strain of 33%. The results of individual experiments (gray lines), the ensemble mean (black line), and ± one standard deviation from the mean (dark gray shaded) are shown (n = 13).

Fig.15

Creep response of tofu subjected to a constant force of 2.5 N (stress = 8.8 kPa). After the initial deformation, the strain continues to increase to a steady state. The results of individual experiments (gray lines), the ensemble mean (black line), ensemble envelope (light gray shaded), and ± one standard deviation.
Creep response of tofu subjected to a constant force of 2.5 N (stress = 8.8 kPa). After the initial deformation, the strain continues to increase to a steady state. The results of individual experiments (gray lines), the ensemble mean (black line), ensemble envelope (light gray shaded), and ± one standard deviation.

Fig.16

Normalized compression BIS response of tofu subjected to a constant force of 2.5 N (stress = 8.8 kPa). After the initial deformation, the impedance rises slowly toward a steady state. The results of individual experiments (gray lines), the ensemble mean (black line), ensemble envelope (light gray shaded), and ± one standard deviation from the mean (dark gray shaded) are shown (n = 12).
Normalized compression BIS response of tofu subjected to a constant force of 2.5 N (stress = 8.8 kPa). After the initial deformation, the impedance rises slowly toward a steady state. The results of individual experiments (gray lines), the ensemble mean (black line), ensemble envelope (light gray shaded), and ± one standard deviation from the mean (dark gray shaded) are shown (n = 12).

Fig.17

Parametric plot of the creep and normalized compression BIS responses of tofu subjected to a constant force of 2.5 N (stress = 8.8 kPa) showing a slight nonlinear increase with increasing strain. The results of individual experiments (gray lines), the ensemble mean (black line), ensemble envelope (light gray shaded), and ± one standard deviation from the mean (dark gray shaded) are shown (n = 12).
Parametric plot of the creep and normalized compression BIS responses of tofu subjected to a constant force of 2.5 N (stress = 8.8 kPa) showing a slight nonlinear increase with increasing strain. The results of individual experiments (gray lines), the ensemble mean (black line), ensemble envelope (light gray shaded), and ± one standard deviation from the mean (dark gray shaded) are shown (n = 12).

Fig. 18

Anticipated behavior of patient bioimpedance for a single dialysis session. Vertical lines represent compression BIS changes (each measurement). Bottom curve represents aggregate compression BIS during dialysis session. Top curve represents actual BIS as measured during a dialysis session. These data will provide the basis for both dry weight determination (via the asymptotic final value, BISAF, and the index of mobilizable fluid (via individual compression time constants).
Anticipated behavior of patient bioimpedance for a single dialysis session. Vertical lines represent compression BIS changes (each measurement). Bottom curve represents aggregate compression BIS during dialysis session. Top curve represents actual BIS as measured during a dialysis session. These data will provide the basis for both dry weight determination (via the asymptotic final value, BISAF, and the index of mobilizable fluid (via individual compression time constants).

BIS coefficients and time constants for tofu under a constant strain of 33% as shown in Fig_ 13_

ParameterFit Value95% Confidence Bounds
ΔZ¯c${{\overline{\Delta Z}}_{c}}$(%)10.88N/A
ΔZ1¯$\overline{\Delta {{Z}_{1}}}$(%)3.161(2.823, 3.498)
ΔZ2¯$\overline{\Delta {{Z}_{2}}}$(%)9.565(9.252, 9.878)
τ1 (s)36.94(33.46, 40.42)
τ2 (s)300.6(257.4, 343.7)

Creep-compliance coefficients and time constants for tofu under a constant force of 2_5 N (strain = 8_8 kPa) as shown in Fig_ 15_

ParameterFit Value95% Confidence Bounds
E0 (kPa)89.61(88.66, 90.56)
E1 (kPa)148(145.4, 150.6)
E2 (kPa)91.7(91.29, 92.11)
τ1 (s)4.517(4.361, 4.673)
τ2 (s)78.72(78.72, 80.15)

Stress-relaxation coefficients and time constants for tofu under a constant strain of 33% as shown in Fig_ 12_

ParameterFit Value95% Confidence Bounds
E0 (kPa)29(28.6,29.3)
E1 (kPa)31.23(29.64, 32.86)
E2 (kPa)30.46(29.74, 31.20)
τ1 (s)3.181(2.866, 3.496)
τ2 (s)45.88(43.36, 48.4)

BIS coefficients and time constants for tofu under a constant force of 2_5 N (strain = 8_8 kPa) as shown in Fig_ 16_

ParameterFit Value95% Confidence Bounds
ΔZ¯c${{\overline{\Delta Z}}_{c}}$(%)4.69N/A
ΔZ1¯$\overline{\Delta {{Z}_{1}}}$(%)1.731(1.668, 1.793)
ΔZ2¯$\overline{\Delta {{Z}_{2}}}$(%)16.83(16.68, 16.98)
τ1 (s)9.905(8.942, 10.87)
τ2 (s)263.7(257.6, 269.8)
DOI: https://doi.org/10.5617/jeb.929 | Journal eISSN: 1891-5469
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Language: English
Page range: 99 - 109
Submitted on: Sep 4, 2014
Published on: Dec 25, 2014
Published by: University of Oslo
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue per year
Keywords:
Bioimpedance,
peripheral edema,
dry weight,
tissue compression,
tofu
Related subjects:
Engineering,
Bioengineering and biomedical engineering,
Biomedical electronics,
Physics,
Spectroscopy and metrology,
Life sciences,
Biophysics,
Medicine,
Biomedical engineering

© 2014 Leo Koziol, John J. Pitre, Joseph L. Bull, Robert E. Dodde, Grant Kruger, Alan Vollmer, William F. Weitzel, published by University of Oslo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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