2nd International Conference on Bioelectromagnetism
February 1998, Melboume AUSTRALIA
EFFECTIVE BIOIMPEDANCE SPECTROSCOPY METHOD FOR
EVALUATION OF BODY CELL WATER COMPARTMENTS
Rodolfo A. Fiorini, G. Dacquino, G.* Arrigo, G.* Colasanti, L. Selicato, G.* D'Amico
]Department of Biomedical Engineering - Milan Polytechnic University
and * Division of Nephrology and Dialysis - S.Carlo Hospital, Milan
Abstract: The traditional Cole or CFC basic
model might offer too coarse estimations in
personalized lhaemodialytic treatment. To take
advantage of the full information content offered
by BIS ins$rumentation the traditional CFC
model can be extended into a more convenient
model: the Extended CFC (ECFC) model. The
ECFC model is used to fit raw bioimpedance
measurements to increase the overall estimation
accuracy of Rlesistance and Reactance terms. An
experimental comparison between CFC, ECFC
model simulations, and experimental data is
presented. Experimental results show that higher
accuracies (at leas? a tenfold improvement) over
the traditional CFC model are easily achieved.
I I
ARe
II
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Figure 1 The Cole or Cole-Fricke-Cole basic
(CFC) dipole used for tra&tional body modelling.
The starting point was extending the basic CFC
model to an "extended" equivalent dipole (Fig. 2).
INTRODUCTION
BIoimpedance Analysis (BIA) consists on the
local injection into human body of a small limited
alternating current and in the measurement of
induced complex impedance (Z). Resistance (R) and
Reactance (X)are then computed by Cole or ColeFricke-Cole (CFC) model (Fig. 1). So. modelling is
essential. because it is the only means of
independently analyzing the individuill components
of a heterogeneous material system [Ol].
To accurately predict body cell water volume,
the mi?rtUre effects need to be accounted for,
because the relationship between R and body water
volume is nonlinear [02]. Hanai theory provides
that compromise [03]. Previous results have
supported that Hanai theory can be used in vivo to
predict ExtraC'elldar Water (ECW). Total Body
Water (TSW), and IntraCellular Water (ICW)
volume [04].
Traditional monofrequency. double and even
triple frequency BIAS present a number of
limitations for personalized haemodialytic treatment
application
[05].
Recent
BIoimpedance
Spectroscopy 131s)guarantees better results for
measured body impedance [OG]. Nevertheless BIS
may give limited results. and cannot exploit the full
potential information content offered by its
measurement data [07], by using the CFC basic
Figure 2 - The "Extended" Cole-Fricke-Cole
(ECFC) dipole, by adding an inductive branch to
the traditional basic CFC structure.
It was called Extended CFC (ECFC) dipole, being
the presence of an additional inductive branch. The
additional branch can be justified taking better into
account the subtle dynamic electro-magnetic
balance of living cells [OS, 09, 101. Then, we
calculated the complex impedance (Z), the whole
body Resistance (R) and the whole body Reactance
(X).Two different simulations were performed
running dedicated MATLAB 4.0 for Windows
programs.
RESULTS
The first simulation was performed using the
traditional basic CFC element for body modelling
(Fig.1). It showed frequency dependent patterns of
R and X much higher. being about 140 SZ for X and
1720 R for R at peak values (Fig. 3), than the
reference experimental ones (about 42 0 and 580 R
respectively at peak values).
In the second case, the ECFC element model
was used for both body and skin-electrode
interaction modelling (Fig. 2). The result provided
more accurate R and X values being respectively
model for traditional body modelling
q T E R I A L S AND METHODS
Xitron 4000B inipedentiometer (SO freqs. from 5
to 1000 KHz) on 5 patients on starting a RDT.
203
February 1998, Melboume AUSTRALIA
2nd lntemationalConferenceon Bioelectromagnetism
EXFEHIMEEIFAL RESISTAM E ( 0 )AFlCl CALCULATEDRESISTAfKE (+)
about 37 0 and 500 L2 at peak values; they match
the experimental data much better than the CFC
based body model ones (Fig.4).
DISCUSSION
No inductance parameters are provided for the
traditional Cole or CFC element model. That
limited point of view can not take into account the
real lumped electro-magnetic interaction properties
of living tissues and “a-priori” excludes the
possibility for biological cell to act as an “active
structure” to reach a possible self-balanced state.
Further basic studies are necessary for a better
understanding of the real interaction between
electro-magnetic fields, biological cells. and body
tissues.
Frequency(kkl
xld
Figure 4 - Experiment (0)and ECFC Simulation
(+): a much better agreement to experimental data.
REFERENCES
[011 K. S. Cole, ~ e m h r a n e s ,ions and impulses.
Berkeley: University of California Press, 1966.
[02] P.M.J.M., De Vries, J.H., Meijer, K., Visser,
V.. Vlaanderen, P.L., Oe, J.M., Donker, and H.,
Schneider. “Measurement of transcellular fluid shift
during haemodialysis Med. Biol. Eng. Comput.,
vol. 27, pp.152-158, 1989.
[03] T., Hanai, “Electrical Properties of
Emulsions”. in Emtrlsion Science, edited by P.H.
Sherman. London: Academic, 1968, pp.354-477.
[04] M.D., Van Loan, P., Withers, J., Matthie, and
P.L., Mayclin, “Use of bio-impedance spectroscopy
(BIS) to determine extracellular fluid (ECF),
intracellular fluid (ICF), total body water (TBW),
and fat-free mass
in Human Body
(hmposition: In Vivo Methods, Models and
A.wessment, ehted by K.J. Ellis and J.D. Eastman.
New York: Plenum, 1993, pp.67-70.
[05] R.A., Fiorini. G., Dacquino, M.. Sivo, G.,
Arrigo, R., Bucci, G., Colasanti, L., Selicato, and
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Skin-Electrode Interface Modeling in Bioinpedance
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Tampere: Ragnar Granit Foundation, 1996, pp. 149150.
[06]A., De Lorenzo, A., Andreoli, J., Matthie, and
P., Withers, “Predicting body cell mass with
bioirnpedance by using theoretical methods: a
technological review”, J. Amer. Physiol. Soc., vol.
0161-7567, pp. 1542-1558, 1997.
[07] R.A., Fiorini, Sistemi di Support0 Attivo,
Milano. Milano: CUSL, 1994.
[08] T., Karu, “Molecular mechanism of the
therapeutic effect of low-intensity laser irradiation”,
Doh?. Akad. SSSR, v01.291 n.5, pp. 1245-1249,
1986.
[09] T., Karu, “Photobiology of low-power laser
effects“, Health Phys., vo1.56 n.5, pp.691-704,
1989.
[lo] T., Karu, “Effects of visible radiation on
cultured cells”, J. Photochem. Photohiol., vo1.25
n.6, pp.1089-1098, 1990.
CONCLUSIONS
The final experimental results show that the
ECFC basic model can be a strong candidate (as an
improved CFC model) for effective body modelling
in haemodalytic research applications. In fact. from
the presented examples, Resistance and Reactance
estimations show a tenfold improvement at least.
‘I,
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Figure 3 - Experiment (0)and CFC Simulation (+):
R and X values show a remarkable difference.
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