How can drift in a calculated volume signal be corrected in spirometry?

To remove the downward sloping baseline in the volume channel (caused by the heating and expansion of inhaled air), users must perform the following calibration procedure.  First, select a region of normal tidal breathing in the data by holding a left mouse click on the Chart View's time axis and dragging.

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Next, select the Spirometry Volume channel calculation from the Channel Calculations pop up menu on the Volume Channel.  Select "Apply volume correction, Normal breaths" in the settings dialog box that appears and click OK. 

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This will apply a correction factor to the volume channel to minimize the breath dependent drift.

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Note: you will need to have the LabChart Spirometry Extension installed to calculate volume from the flow signal and perform the correction mentioned above.

If you require further assistance, please contact your localADInstruments technical support.