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Impedance Ratio Method for Urine Conductivity-Invariant Estimation of Bladder Volume Cover

Impedance Ratio Method for Urine Conductivity-Invariant Estimation of Bladder Volume

Journal of Electrical Bioimpedance
Volume 5 (2014): Issue 1 (January 2014)
By: T. Schlebusch,  J. Orschulik,  J. Malmivuo,  S. Leonhardt,  D. Leonhäuser,  J. Grosse,  M. Kowollik,  R. Kirschner-Hermanns and  M. Walter  
Open Access
|Sep 2014

Figures & Tables

Fig. 1

Variability of urine conductivity in nine patients: Even in a hospitalized environment, high intra- and inter-individual variations are apparent.
Variability of urine conductivity in nine patients: Even in a hospitalized environment, high intra- and inter-individual variations are apparent.

Fig. 2

Experimental set-up of in-vivo measurement for controlled volume instillation: The EIT belt is placed cranial of the iliac crest and a standard urinary balloon catheter is used for fluid instillation by a 50 ml syringe.
Experimental set-up of in-vivo measurement for controlled volume instillation: The EIT belt is placed cranial of the iliac crest and a standard urinary balloon catheter is used for fluid instillation by a 50 ml syringe.

Fig. 3

Influence of urine conductivity on EIT global impedance: the slope of the impedance-volume-mapping is influenced by urine conductivity.
Influence of urine conductivity on EIT global impedance: the slope of the impedance-volume-mapping is influenced by urine conductivity.

Fig. 4

The Impedance Ratio Method uses three tetrapolar measurements at front (ventral, Uf /If ), side (Us/Is) and back (dorsal, Ub/Ib) positions.
The Impedance Ratio Method uses three tetrapolar measurements at front (ventral, Uf /If ), side (Us/Is) and back (dorsal, Ub/Ib) positions.

Fig. 5

Sensitivity field of the measurement positions showing the spatial difference in sensitivity regions, [1/m4].
Sensitivity field of the measurement positions showing the spatial difference in sensitivity regions, [1/m4].

Fig. 6

Measurement system schematics with Agilent E4980 impedance measurement device, custom built multiplexer and phantom. A PC is used to control injection frequency and selection of current injection and voltage measurement electrodes.
Measurement system schematics with Agilent E4980 impedance measurement device, custom built multiplexer and phantom. A PC is used to control injection frequency and selection of current injection and voltage measurement electrodes.

Fig. 7

In-vitro tank filled with agar as a multi-frequency EIT phantom: A cylindrical cavity is cut into the agar and filled with solutions of different conductivities to model varying urine conductivity. The sketches visualize the spatial arrangement (left) and variation in cavity size (right).
In-vitro tank filled with agar as a multi-frequency EIT phantom: A cylindrical cavity is cut into the agar and filled with solutions of different conductivities to model varying urine conductivity. The sketches visualize the spatial arrangement (left) and variation in cavity size (right).

Fig. 8

In-silico results for single-frequency variant using absolute values: The method is unreliable for urine conductivities in the range of surrounding tissue impedances (4 mS/cm in this case).
In-silico results for single-frequency variant using absolute values: The method is unreliable for urine conductivities in the range of surrounding tissue impedances (4 mS/cm in this case).

Fig. 9

In-silico results for single-frequency variant using imaginary parts: For urine volumes higher than 100 ml the method works as expected.
In-silico results for single-frequency variant using imaginary parts: For urine volumes higher than 100 ml the method works as expected.

Fig. 10

In-silico results for frequency-differential variant using absolute values: Comparable result to the single-frequency variant using imaginary parts.
In-silico results for frequency-differential variant using absolute values: Comparable result to the single-frequency variant using imaginary parts.

Fig. 11

Noise susceptibility of the three methods for given SNR: Due to the smaller amplitude of the impedance differences, the multi-frequency method is much more susceptible to noise than the single frequency method.
Noise susceptibility of the three methods for given SNR: Due to the smaller amplitude of the impedance differences, the multi-frequency method is much more susceptible to noise than the single frequency method.

Fig. 12

In-vitro results for single-frequency variant using absolute values: the influence of urine conductivity is not suppressed completely.
In-vitro results for single-frequency variant using absolute values: the influence of urine conductivity is not suppressed completely.

Fig. 13

In-vitro results for single-frequency variant using imaginary parts: good suppression of urine conductivity variation in the volume estimation result.
In-vitro results for single-frequency variant using imaginary parts: good suppression of urine conductivity variation in the volume estimation result.

Fig. 14

In-vitro results for frequency-differential variant using absolute values: the results from simulation could not be reproduced, probably by an impact of varying electrode contact impedances on the measurement device.
In-vitro results for frequency-differential variant using absolute values: the results from simulation could not be reproduced, probably by an impact of varying electrode contact impedances on the measurement device.
DOI: https://doi.org/10.5617/jeb.895 | Journal eISSN: 1891-5469
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Language: English
Page range: 48 - 54
Submitted on: Jun 11, 2014
Published on: Sep 9, 2014
Published by: University of Oslo
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue per year
Keywords:
Impedance tomography,
cystovolumetry,
volume estimation
Related subjects:
Engineering,
Bioengineering and biomedical engineering,
Biomedical electronics,
Life sciences,
Biophysics,
Medicine,
Biomedical engineering,
Physics,
Spectroscopy and metrology

© 2014 T. Schlebusch, J. Orschulik, J. Malmivuo, S. Leonhardt, D. Leonhäuser, J. Grosse, M. Kowollik, R. Kirschner-Hermanns, M. Walter, published by University of Oslo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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