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Pulmonary Function Test • Publication 014181-001 Rev 02 • www.datasci.com ©2023 Data Sciences International
FV (Flow Volume) Test
With this test, more than any other, you should be concerned about the position and comfort of the animal.
Ripples or Squiggles Near the End of the Flow-Volume Curve
If you observe squiggles near the end of the Flow Volume curve, it is probably because there is mucus, goo, or
condensation in the lung or trach tube. For larger animals, we recommend you suction it out. For mice, just change
either the trach tube or the mouse.
A Flat Top of the Flow Volume Curve
This does not occur often, but if you look at a Flow-Volume curve, and it is perfectly flat at the top, this is most
likely a saturated flow transducer. What to do:
• Make sure the calibration procedure was performed properly.
• Make sure that the High Flow input is connected to Lead 1.
• Reduce the gain on the flow preamp and recalibrate the High Flow, Flow, and FRC flow.
• Make sure that there are no obstructions in the tracheal line of the manifold.
A Dip in the Center of the Flow-Volume Curve
A dip in the flow near mid volume of the Flow-Volume curve could be a real result of a physiological condition,
however, when it is observed you should check a couple things to make sure it is not something else. This shape is
caused by a temporary obstruction in the expiration line. One example may be a collapsed tube either in or outside
the lung. A balloon without cotton inside will almost always do this as the flabby piece of balloon covers the hole
in the trach tube temporarily. You might just try repositioning the animal to make sure the tracheal line is straight
and not putting the trachea at any angles.
Generally Rounded Flow-Volume Curve
The FVC parameter (forced vital capacity) should not be too far from what you expect. If the tracheal tube is
inserted too deeply in the lung, the end of the tracheal tube may pass the first bifurcation of the lung. The result is
that you are performing your test on only one half of the lung.
FVC Value is Wildly Different Than IC
Though rare, we have seen data where the expired volume is very small when compared to the inspired volume.
While this can be caused by a physical obstruction in the airway or tubing, for example, a tube crimps during the
expiratory phase, you may want to confirm the calibration for the Flow and High Flow signals. In general, the
effective range of the High Flow should be 8 times larger than the effective range of the Flow signal. A jumper on
the Signal Generator card can change this to 4 times.
4 times has been recommended for mouse systems. The High Flow signal is only used during expiration of the
FV test, so problems with the High Flow calibration should not impact other tests.
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