SE-RDA User Instructions 100507-03 B
Copyright © 2021 The S.E.A. Group
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2.
Edit the value by trial and error until the trace is as close to zero as possible
(each time toggling Press/Flow to refresh the display).
After completing the offset correction process, save the file.
Adjustable threshold cursor
The horizontal yellow line on the detail graph area can be moved vertically, either by
dragging and dropping it or by entering a flow value in the field below it (16).
In the example above the threshold is set at -135 l/min. The selected data range is 18m
41s. The total inhaled volume (-V, L) is 896.9 litres, and the minute volume is 48 l/min.
Vlow % indicates 46%. This means that the air volume below the threshold line is 46%
of the total inhaled volume. In other words, 46% of the total inhaled volume passed
through the filter at a flow rate of 135 l/min or greater.
Vhi % indicates the remainder of the inhaled volume – i.e.: (100 – Vlow)%.
The figure below illustrates how the volumes are calculated. In this example the selected
range is a single breath. The minute volume for this breath is 78.2 litres; PIFR is 220
l/min.
The volume of air that passed through the filter at a flow rate of 135 l/min or greater
(representing 65% of the duration of the inhalation phase) is indicated by the yellow
area. It represented 81% of the total volume of the breath.
Note: This feature is designed to be used on the inhalation side of the curve only. If the
threshold is set to the positive (exhalation) side the Vhi and Vlow data become
meaningless.
