Seca 515 - Manual (Page 48)

48 •
seca specialty: Coordinate system
with tolerance ellipses
In addition to the classic display of evaluation modules in numerical
values, bar graphs, and percentile curves, the
seca 515/514 uses
coordinate systems with tolerance ellipses for the graphic display of body
impedance and fat-mass indices.
This form of graphic display was developed by Professor A. Piccoli for the
interpretation of body impedance under the name Bioelectric Impedance
Vector Analysis (BIVA).
The transfer of this principle to the display and interpretation of the fat-
mass indices is a new development from seca in collaboration with the
Institute for Human Nutrition and Food Studies at the University of Kiel.
Biolelectric impedance analysis (BIVA)
According to Professor A. Piccoli, the BIVA is a graphical display of the
electrical resistances of the body. To this end, the impedance of the
patient is displayed as a measurement point in a coordinate system:
Capacitive resistance (X
C
) on the ordinate, ohmic resistance (R) on the X-
axis. Both sizes X
c
and R are considered relative to body size (length of the
electrical conductor).
With vector display, a proband 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 the fluid volume, while changes on the Y axis indicate an
increase or decrease in the body cell mass.
The quadrants in the coordinate system are named correspondingly:
• I: X
C
high, R high = lower proportion of water
• II: X
C
low, R high = higher proportion of cells
• III: X
C
low, R low = lower proportion of cells
• IV: X
C
high, R low = higher proportion of water
An additional advantage of the BIVA is the comparison of an individual
measured value with reference values. The 50%, 75%, and 95%
percentiles are entered into the coordinate system as tolerance ellipses.
Fat mass indices (FFMI and FMI)
The system developed by Professor A. Piccoli can be applied to the
display of the fat-mass indices on the basis of the work carried out by
Schutz et al., who describe four typical situations for the relationship of
FFMI and FMI.
The quadrants in the coordinate system are named correspondingly:
• I: FFMI high, FMI high = high muscle mass
• II: lFFMI low, FMI high = obesity
• III: FFMI low, FMI low = chronic energy deficiency
• IV: FFMI high, FMI low = low muscle mass
In addition, the FFMI (X axis) and the FMI (ordinate) are also plotted on the
axes of the coordinate system for FFMI and FMI. The 50%, 75%, and 95%
percentiles for the fat mass indices are displayed as tolerance ellipses.
Z(R)
Z(Xc)
II I
IV III
95th
75th
50th
y
x
Z(FMI)
Z(FMMI)
95th
y
x
75th
50th
II I
IV III