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Monitoring thoracic fluid content using bioelectrical impedance spectroscopy and Cole modeling

Silviu Dovancescu
Silviu Dovancescu
, 
Salvatore Saporito
Salvatore Saporito
, 
Ingeborg H. F. Herold
Ingeborg H. F. Herold
, 
Hendrikus H. M. Korsten
Hendrikus H. M. Korsten
, 
Ronald M. Aarts
Ronald M. Aarts
 and 
Massimo Mischi
Massimo Mischi
   | Dec 29, 2017
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Article Category: Articles
Published Online: Dec 29, 2017
Page range: 107 - 115
Received: Oct 31, 2017
DOI: https://doi.org/10.5617/jeb.5611
Keywords
© 2017 Silviu Dovancescu, Salvatore Saporito, Ingeborg H. F. Herold, Hendrikus H. M. Korsten, Ronald M. Aarts, and Massimo Mischi, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Figure 1

Schematic illustration of an inflatable leg sleeve including 12 circular air chambers. Each chamber is inflated individually to compress a section of the leg. The pressures in the individual chambers form a gradient along the leg. The highest pressure (dark green) is applied to the foot. Through external compression of the leg, a part of the peripheral blood is shifted towards the upper body.
Schematic illustration of an inflatable leg sleeve including 12 circular air chambers. Each chamber is inflated individually to compress a section of the leg. The pressures in the individual chambers form a gradient along the leg. The highest pressure (dark green) is applied to the foot. Through external compression of the leg, a part of the peripheral blood is shifted towards the upper body.

Figure 2

Leg compression and measurement protocol. The blue line is a qualitative representation of the pressure applied to the legs: the up-slope marks the gradual pressure build-up during the inflation of the leg sleeves; the downward step marks the pressure drop in the air chambers as the valves are opened for deflation. The black line represents the continuous BIS measurement, black rectangles indicate the four periods of end-expiratory breath-hold used in the analysis. (BIS = bioimpedance spectroscopy).
Leg compression and measurement protocol. The blue line is a qualitative representation of the pressure applied to the legs: the up-slope marks the gradual pressure build-up during the inflation of the leg sleeves; the downward step marks the pressure drop in the air chambers as the valves are opened for deflation. The black line represents the continuous BIS measurement, black rectangles indicate the four periods of end-expiratory breath-hold used in the analysis. (BIS = bioimpedance spectroscopy).

Figure 3

Principles of bioimpedance spectroscopy. (a) Flow of electrical current through biological tissue: low-frequency currents (f→0) flow around the cells through the extracellular fluid while high-frequency currents (f→∞) penetrate the cell membranes and flow through intracellular and extracellular fluid. (b) Simplified electrical circuit of the tissue bioimpedance consisting of two resistors and a capacitor accounting for the resistances of extracellular (RE) and intracellular (RI) fluids, and the capacitance of cell membranes (CM), respectively. (c) Qualitative representation of bioimpedance spectroscopy measurement points (Z(f)) in the complex bioimpedance plane, the corresponding circular arc centered in (RC,XC), and the extrapolated values at low frequencies (f→0, Z(f)=R0 = RE) and high frequencies (f→∞, Z(f)=R∞ = Rg ∥ RI) according to the Cole model.
Principles of bioimpedance spectroscopy. (a) Flow of electrical current through biological tissue: low-frequency currents (f→0) flow around the cells through the extracellular fluid while high-frequency currents (f→∞) penetrate the cell membranes and flow through intracellular and extracellular fluid. (b) Simplified electrical circuit of the tissue bioimpedance consisting of two resistors and a capacitor accounting for the resistances of extracellular (RE) and intracellular (RI) fluids, and the capacitance of cell membranes (CM), respectively. (c) Qualitative representation of bioimpedance spectroscopy measurement points (Z(f)) in the complex bioimpedance plane, the corresponding circular arc centered in (RC,XC), and the extrapolated values at low frequencies (f→0, Z(f)=R0 = RE) and high frequencies (f→∞, Z(f)=R∞ = Rg ∥ RI) according to the Cole model.

Figure 4

Electrode placement for trans-thoracic bioimpedance measurements: two electrodes (red and green) are used for the application of an excitation current (I(t)), and two electrodes for the measurement of the voltage drop (V(t)).
Electrode placement for trans-thoracic bioimpedance measurements: two electrodes (red and green) are used for the application of an excitation current (I(t)), and two electrodes for the measurement of the voltage drop (V(t)).

Figure 5

Bioimpedance spectra before (red) and after (blue) leg compression. Dashed circular arcs mark the extrapolated values according to the Cole model.
Bioimpedance spectra before (red) and after (blue) leg compression. Dashed circular arcs mark the extrapolated values according to the Cole model.

Figure 6

Bioimpedance trends at multiple frequencies in one study subject. Each line is a local regression curve indicating the temporal evolution of resistance (top) and reactance (bottom) for a single frequency on the Cole arc. Local regression is used to suppress cardio-respiratory artifacts. The trends show a linear decrease in bioimpedance (resistance and reactance) during the inflation of the leg sleeves, a plateau during the maintenance of the target pressure, and a return to baseline after the release of pressure from the leg sleeves. The decrease in resistance and reactance reflects the translation and the contraction of the Cole arc, respectively.
Bioimpedance trends at multiple frequencies in one study subject. Each line is a local regression curve indicating the temporal evolution of resistance (top) and reactance (bottom) for a single frequency on the Cole arc. Local regression is used to suppress cardio-respiratory artifacts. The trends show a linear decrease in bioimpedance (resistance and reactance) during the inflation of the leg sleeves, a plateau during the maintenance of the target pressure, and a return to baseline after the release of pressure from the leg sleeves. The decrease in resistance and reactance reflects the translation and the contraction of the Cole arc, respectively.

Figure 7

Evolution of BIS measures throughout the leg compression protocol in one subject. Gray dots are values obtained during periods of free breathing, black dots are values corresponding to periods of end-expiratory breath hold before, during and after leg compression, blue lines are local regression curves fitted to the data. (R0: resistance at low frequencies; R∞: resistance at high frequencies; RI: resistance intracellular fluids; fc: characteristic frequency of the tissue; α: distribution of relaxation times; K: ratio between resistance of extra- and intra-cellular fluids; R: radius of impedance arc; Xc: depression of the center of impedance arc; A: impedance arc segment area. BIS = bioimpedance spectroscopy).
Evolution of BIS measures throughout the leg compression protocol in one subject. Gray dots are values obtained during periods of free breathing, black dots are values corresponding to periods of end-expiratory breath hold before, during and after leg compression, blue lines are local regression curves fitted to the data. (R0: resistance at low frequencies; R∞: resistance at high frequencies; RI: resistance intracellular fluids; fc: characteristic frequency of the tissue; α: distribution of relaxation times; K: ratio between resistance of extra- and intra-cellular fluids; R: radius of impedance arc; Xc: depression of the center of impedance arc; A: impedance arc segment area. BIS = bioimpedance spectroscopy).
eISSN:
1891-5469
Language:
English
Publication timeframe:
Volume Open
Journal Subjects:
Engineering, Bioengineering and Biomedical Engineering, Biomedical Electronics, Life Sciences, Biophysics, Medicine, Biomedical Engineering, Physics, Spectroscopy and Metrology
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