p/n 18603-001, Rev. C LTV
®
1200/1150 Ventilator Service Manual Page 7-23
Advanced Diagnostic Procedures
Advanced Vte Diagnostic Procedures
If the ventilator Monitored Exhaled Volume (Vte) readout, Delivered Volume to the lung,
Target Pressures or Inspired Volumes (LTM only) appear incorrect; perform the following
checkout procedures.
• When instructed to replace a subassembly/component that fails any of the following
checkout procedures, verify the original problem is resolved once the
subassembly/component has been replaced. If the original problem is not resolved,
continue through the next Advanced Diagnostic Checkout procedure.
Transducer Null Checkout
Check the null or zero of the transducer for drift as follows:
1) Power up the unit in VENT CHECK and select the XDCR ZERO menu.
2) Record the figures for the Airway Pressure (AP) and Flow Transducer Wide Channel
(FDw) (null figures from the time the unit was last calibrated).
3) Perform an auto zero by pressing Select. It is considered normal if the figures change
slightly, however;
• If the figures for AP change by more than 50, the Airway Pressure transducer may
be faulty and the analog PCBA should be replaced. See Analog Board Assembly in
Chapter 8 for instructions.
• If the figures for FDw change by more than 50, the Flow Sensor transducer may be
faulty and the analog PCBA should be replaced. See Analog Board Assembly in
Chapter 8 for instructions.
• If the figures for AP and
FDw change by less than 20, the unit passes this test and
the Pneumatic System Checkout tests are to be performed.
Pneumatic System Checkout
Check the pneumatic system as follows:
1) Apply 50 cmH
2
O to the high side port, monitor the pressure with a calibrated,
independent pressure meter for 1 minute and record any drop in pressure.
Then apply 50 cmH
2
O to the low side port, monitor the pressure with a calibrated,
independent pressure meter for 1 minute and record any drop in pressure.
• If a pressure drop for either the high or the low side port exceeds 1 cmH
2
O, check
all internal plumbing and the solenoid manifold for leaks, replace any damaged
tubing or components and repeat the test.
2) Lay the unit with the front panel up, running in Volume mode and set the Breath Rate
to 12, Tidal Volume to 500 ml and Inspiration Time to 1.5 seconds. Attach a test lung
with a compliance of 10ml/cmH
2
O and a resistance of 5 cm/L/sec and allow the unit to
warm up for one hour.
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