Instruction manual

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5 Analysis 48
Figure 5-3: Integral with Zero
The Reset control in the Integral
Setup dialog window determines when
the Integral or running count will reset
itself to zero. This option allows the
Integral to reset itself after a preset
time. This is a useful option if the data
being integrated contains artifacts that
move the Integral artificially up or
down. The Reset function keeps the Integral trace in the field of view. In the respiration
example, if inhaled air is at 20
o
C and exhaled air is closer to body temperature, then exhaled air
has a larger volume. Since the subject exhales more than he or she inhales, the integral record
will have a slow upward drift. Resetting the trace periodically will return it to zero.
Activating Integral
Transforms
All Integral functions are selected in the same manner. To apply any of these functions to a
channel, click on the Add Function button in the Channel bar. Select Integral from the
Function menu and a submenu appears. Select one of the functions in the submenu. Click Start
in the Main window to begin recording.
Derivative The Derivative function calculates the derivative at each point in the raw data, and then
displays it on the calculated channel. On the channel where the Derivative is displayed, the
units are changed to the units of the raw data channel/second. Higher order derivatives can be
calculated by applying a derivative function to a derivative channel.
Activating
Derivative
Function
To apply the derivative function to a channel, click on the Add Function button in the Channel
bar. Select Derivative from the Function menu. Click Start in the Main window to begin
recording.
Spirometry The Spirometry function is a specialized version of the integral function for use with the WPI
spirometer. This transducer, which measures respiratory volumes, is a sensitive air flow sensor.
DataTrax2 integrates the flow values measured by the sensor and displays volume. The settings
for this integration are specifically designed for volume calculations.
Each WPI spirometer has a calibration value on it. This value can be entered in the
Spirometer Calibration window. If the user has a calibration syringe and has recorded data
where a known volume of air was pushed through the spirometer, this data will be displayed in
the graph window. Place the first cursor at Zero Volume and the second cursor at X Volume.