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Pulmonary Function Test • Publication 014181-001 Rev 02 • www.datasci.com ©2023 Data Sciences International
PV (Pressure Volume) Test
In this test, you need to watch out for a few things:
• The flow was properly zeroed during calibration.
• The expiratory duration is long enough and without attempts from the subject to breathe on its own.
• There should be no leaks in the tracheal line.
• Dead space in the expiratory line affecting the upper side of the curve.
Test Starts When Flow Is Zero
Just like the FRC test, the PV test must begin at FRC so that it can accurately determine IC. If IC is not measured
properly, your TLC measurement will be off as well. Check that the test starts when the flow is at zero, and the
volume is at a minimum. The volume curve is reset at the start of the test, so you may see it step up, but you
should look to ensure that the volume appears to be at a minimum.
At TLC, Volume Rises as Pressure Falls
If pressure drop is accompanied with a slight rise in the volume, then some air escaped from the trachea into the
chamber. Check that you tied the tracheal cannula tightly.
Sources of leak to consider:
• where the tracheal cannula attaches to the manifold,
• where the cannula is tied to the trachea,
• in the cannula itself.
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