Dräger PulmoVista 500, Manual, Page: 35 / 56

Useful Tools and Tips
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3.3. FILTraTIOn
By default, PulmoVista
®
500 processes unfiltered raw data and
displays it accordingly. Since even smallest changes are detected with this
technology, it is also possible to display simultaneous superimposed effects.
Thus, e.g. pulmonary function as well as cardiac or perfusion related impedance
changes are displayed. A functional pulmonary EIT might be better interpreted if
superimposed effects, such as those caused by the cardiac function, are
filtered out. For this purpose, the device has filter options such as
low-pass and
band-pass filters, with which a targeted suppression of impedance signals is
possible. This option can be set in the menu under ›Display‹.
Low pass filter:
Display of impedance changes below a certain frequency
Example: Only respiratory signals are of interest, i.e. signals
with a frequency in the rage of the respiratory rate but below
the heart rate, e.g. HR – 20.
Band pass filter:
Display of impedance changes within a certain frequency
range
Example: Only cardiac-related impedance signals are of
interest, e.g. signals with a frequency of HR ± 20.
Electromagnetic radiation causes artifacts that make it difficult or even
impossible to qualitatively evaluate EIT images. Artifacts can negatively affect
the baseline at the end of expiration that interpretation of the tidal images is
no longer possible.
Special filter techniques of PulmoVista
®
500 allow the elimination of image
artifacts, making EIT images interpretable again. The setting can be found in
the menu item ›Display‹.
Recommendation: Leave the artifact filter turned on.