Definition/Measurement units (if applicable)
Center of
Ventilation
(CoV)
Weighted geometrical Center of Ventilation distribution within the
Lung ROI
,
computed by weighing each
Lung Pixel Relative Tidal Stretch
value. The
Center
of Ventilation
is a functional EIT measure used to quantify the distribution of
ventilation.
The vertical component of the Center of Ventilation (CoV(v)) (9.10) characterizes
the ventilation distribution in vertical direction and is expressed as a fraction of the
vertical
Lung ROI
height. The horizontal component of the Center of Ventilation
(CoV(h)) (9.10) characterizes the ventilation distribution in horizontal direction
and is expressed as a fraction of the horizontal
Lung ROI
width. Notice that
CoV(v) defines the position of the
Horizon of Ventilation
(HoV).
Represented as an image point. Coordinates quantified in % of
Lung ROI
width
and shown in scale.
Index
calculated once per
Analysis Interval.
CoV(v) and CoV(h) are
additionally calculated
upon each
rotation
change
BB
and
TB-I
modes
Dependent
Silent Spaces
(DSS)
The subset of
Lung Pixels
having RTS-values smaller or equal than 10% and being
localized below the HoV, i.e.
Silent Spaces
being localized in dependent lung
areas.
Quantified in % of
Lung ROI
area.
Index
calculated once per
Analysis Interval
and upon
each
rotation
change
BB
and
TB-I modes.
Voltages obtained during EIT measurement, i.e. the voltages resulting at a
very weak alternating currents.
EIT raw
data and all thereof derived
EIT images
,
waveforms, indices
and
parameters.
Any kind of image reconstructed/derived from
EIT raw data.
The intrathoracic volume the impedance changes of which contribute to the
generated
EIT data
(i.e. the intrathoracic volume probed by EIT).
Being centered around the
belt plane
the
EIT sensitivity region
is roughly lens-
shaped: close to the body surface the thickness of the
EIT sensitivity region
corresponds to at least the width of the belt (Table 13-13) and increases towards
the central region of the thorax to reach a thickness of roughly one half to two-
thirds of the thorax width.
End-Expiratory
Lung
Impedance
(EELI)
Minimum of the
Plethysmogram
within an
Analysis Interval
. Assuming that the
occurrence of the minimum corresponds to the end of an expiration, this
minimum can be interpreted as
Lung Impedance
at an end-expiratory time point,
therefore
End-Expiratory Lung Impedance
.
EELI is related to the end-expiratory lung volume (EELV) if exhaling against a
PEEP and, if exhaling against ambient pressure, to the Functional Residual
Capacity (FRC), when breathing normally, or the Residual Volume (RV), in forced
expiration.
Quantified in arbitrary, not displayed, units. Auto-scaled trend display.
Index
calculated once per
Analysis Interval
BB
and
TB-I modes
.
End-Inspiratory
Lung
Impedance
(EILI)
Maximum of the
Plethysmogram
within an
Analysis Interval
.
Assuming that the occurrence of the maximum corresponds to the end of an
inspiration, this maximum can be interpreted as
Lung Impedance
at an end-
inspiratory time point, therefore
End-Inspiratory Lung Impedance
.
EILI is related to end-inspiratory lung volume and, therefore, the difference
between EILI and EELI to tidal volume.
Quantified in arbitrary, not displayed, units. Auto-scaled trend display.
Index
calculated once per
Analysis Interval
BB
and
TB-I modes.
Electrode with insufficient skin contact respectively impedance coupling to the
skin. Due to the associated, excessive skin contact impedance, current injection
and voltage measurements are not possible with this electrode.
Functional
Lung Spaces
(FLS)
The subset of
Lung Pixels
having RTS-values greater than 10%.
Functional Lung Spaces
reflect the percentage of lung areas with non-negligible
impedance change during breathing. As such they are meant to represent the
percentage of ventilated lung regions. They are related to what in literature is
referred to as Functional Lung Size [1] or size of the available lung volume, i.e. the
percentage of the aerated remaining lung.
Quantified in % of Lung ROI area.
Index
calculated once per
Analysis Interval
BB
and
TB-I modes
.
Image (tomogram) displaying, for a given image frame, the regional impedance
distribution within the
Thorax ROI
(i.e. the
zero reference image
) with respect to a
moving baseline impedance distribution.
Typically, not shown as an individual image but as real-time display of
continuously updated series of tomograms in a movie-like sequence. The movie-
like display of Global Dynamic Images provides visual feedback about
measurement quality and plausibility.
Pixel values quantified in arbitrary units and represented in color scale.
Calculated once per
image frame all modes.
Horizon of
Ventilation
(HoV)
The horizontal plane through the
Center of Ventilation
, perpendicular to the
gravity vector. The horizontal line through the
Center of Ventilation
displayed in
certain
EIT images
corresponds to the line of intersection of the
belt plane
with
the HoV.
HoV divides
EIT images
into non-dependent (upper part of image) and
Calculated once per
Analysis Interval
and upon
each
rotation
change
BB
and
TB-I modes.
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