Product Manual

Medical basis • 49
English
seca specialty: co-ordinate system
with tolerance ellipses
In addition to the classic display of evaluation parameters in numerical values,
bar graphs and percentile curves, the
seca 515/514 uses co-ordinate systems
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
a measurement point in a co-ordinate system: capacitive resistance (X
C
) on
the y axis, ohmic resistance (R) on the x axis. Both variables X
c
and R are
considered relative to height (length of the electrical conductor).
With vector display, a test subject can be investigated simultaneously with
regard to his/her total body water – R – and his/her body cell mass – X
c
.
Changes to the measurement point (R, Xc) parallel to the x axis indicate
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
C
high, R high = decreasing proportion of water
• II: X
C
low, R high = increasing body cell mass
• III: X
C
low, R low = increasing proportion of water
•IV: X
C
high, R low = decreasing body cell mass
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
et al., who describe four typical situations for the relationship of FFMI and
FMI.
The quadrants in the co-ordinate system are named correspondingly:
• I: FFMI high, FMI high = increasing obesity
• II: FFMI low, FMI high = increasing sarcopenic obesity
• III: FFMI low, FMI low = increasing thinness
• 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
ellipses.
Z(R)
Z(Xc)
II I
IVIII
95th
75th
50th
y
x
Z(FMI)
Z(FMMI)
95th
y
x
75th
50th
II I
IVIII