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seca specialty: co-ordinate system
with tolerance ellipses
y
Z(Xc)
II
III
y
II
Z(FMI)
III
In addition to the classic display of evaluation parameters in numerical values,
bar graphs and percentile curves, the
with so-called tolerance ellipses for the graphical display of body impedance
and fat-mass indices.
This form of graphical display, named "bioimpedance vector analysis" (BIVA),
was developed by Professor A. Piccoli for the interpretation of body imped-
ance.
The transfer of this principle to the display and interpretation of fat mass indi-
ces, on the other hand, is a new development by seca in collaboration with
the Institute for Human Nutrition and Food Studies at the University of Kiel.
Bioimpedance vector analysis (BIVA)
Professor A. Piccoli's BIVA is a graphical representation of the electrical resis-
tances of the body. To this end, the impedance of the patient is displayed as
I
a measurement point in a co-ordinate system: capacitive resistance (X
the y axis, ohmic resistance (R) on the x axis. Both variables X
95th
considered relative to height (length of the electrical conductor).
75th
With vector display, a test subject can be investigated simultaneously with
50th
regard to his/her total body water – R – and his/her body cell mass – X
x
Changes to the measurement point (R, Xc) parallel to the x axis indicate
Z(R)
changes to fluid volume, whilst changes on the y axis indicate an increase or
decrease in body cell mass.
The quadrants in the co-ordinate system are named correspondingly:
• I: X
• II: X
IV
• III: X
• IV: X
An additional advantage of BIVA is the comparison of an individual measured
value to reference values. The 50 %, 75 % and 95 % percentiles are entered
in the co-ordinate system in the form of tolerance ellipses.
Fat mass indices (FFMI and FMI)
The system developed by Professor A. Piccoli can also be applied to repre-
sentation of the fat mass indices on the basis of work conducted by Schultz
I
et al., who describe four typical situations for the relationship of FFMI and
FMI.
95th
The quadrants in the co-ordinate system are named correspondingly:
75th
• I: FFMI high, FMI high = increasing obesity
50th
x
• II: FFMI low, FMI high = increasing sarcopenic obesity
• III: FFMI low, FMI low = increasing thinness
Z(FMMI)
• IV: FFMI high, FMI low = increasing skeletal muscle mass
In addition, the FFMI (x axis) and the FMI (y axis) are also plotted for FFMI and
FMI on the axes of the co-ordinate system. The 50 %, 75 % and 95 % per-
centiles are also shown for the fat mass indices in the form of tolerance
IV
ellipses.
high, R high = decreasing proportion of water
C
low, R high = increasing body cell mass
C
low, R low = increasing proportion of water
C
high, R low = decreasing body cell mass
C
uses co-ordinate systems
seca 515/514
c
Medical basis • 49
English
) on
C
and R are
.
c
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