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Pulmonary Function Test • Publication 014181-001 Rev 02 • www.datasci.com ©2023 Data Sciences International
FV Test
• The inspiration to 30 cm H20 phase of the FV test is not triggered
o This can happen if the end of the breaths cannot be determined during the breath history phase.
The slow expiration phase is triggered when the breath hold phase ends.
o Make sure the calibration is good for all leads.
o Check the system for leaks (See the Leaks section below).
• 30 cm H20 of pressure cannot be achieved during the inspiration phase
o There could be a leak in the tracheal tube surgery. Check the surgery site and the tubing
connection to the manifold.
o The inspiration flow rate is too low. Increase in inspiration flow slightly and repeat the test (See
the Setting Inspiration Flow section on page 25).
o There could be a leak in the valves (See the Leaks section below)
o If you have a test lung for your species type, connect it and attempt the PV test. If the test
passes, the issue was probably with the tracheal surgery or the connection to the manifold. If it
still fails, try the other items in this list.
o 30 cm H20 must be reached within a unique specified time for each species, or the inspiration
will time out. Keep in mind that the rate you need to achieve for a “good” test is usually less than
the time out value (See the Setting Inspiration Flow section on page 25). For example, with mice
the inspiration time out is 5 seconds. However, the best inspiration rate for the average sized
mouse is to reach 30 cm H20 in 1-2 seconds.
• The fast expiration phase failed
o Check the connection from the fast flow valve to the negative pressure reservoir.
o Ensure the negative pressure dial is set to -40 on the PFT controller. It can be set as high as -50
cmH20 if needed.
o Check the system for leaks (See the Leaks section below).
Leaks
The principal cause of problems you will find are due to leaks.
Leaks may occur at any point where there is a detachable junction between two air passages.
While the chamber and valve assembly are shipped with no leaks, the equipment is very fragile and even the
jostling during shipping may cause some leakage. However, we have found that the most common place for leaks
is the tracheal connection, where the cannula enters the animal. Other common causes for leaks include -
equipment being moved from one place to another, and air tubes being connected and disconnected.
Common Symptoms
If any of the following are occurring in your experiment, consider that there may be a leak in your system, and use
the “Guide to Fixing Leaks”.
• The system has trouble delivering inspirations (“Unable to inflate to 30 cmH2O”).
• The system has trouble performing forced expirations.
• Hold period does not appear flat, but drifts upwards (in the PV maneuver).
• Expiration does not cross zero volume (also in the PV maneuver).
• The software has trouble analyzing data.
General Suggestions
• In general, make sure that all connections are snug and airtight.
• Check the connection of the tracheal tube to the animal. Make sure the tube is tied in tightly,
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