504-2033 Iss. 1j 12 April 2005
10.2 Check function of Air Entrainment N.R.V.
i) Set the Tidal Volume to 200 mL, the Frequency control to 25 breaths per minute and
the Relief valve to maximum.
ii) Select 'No Air Mix'.
iii) With a Patient hose and patient valve connected completely occlude the outlet port of
the patient valve and note the movement of the needle on the Inflation Pressure Monitor
on the front of the ventilator. (This is particularly important for the EP Option as no
pressure will be indicated unless a complete EP circuit is connected.) The needle
should rapidly rise to the 8x100Pa (80 cmH
2
O) mark. The pneumatic audible alarm
should sound and the red High Pressure LED (top left) should start flashing after 1/10
second. The High Priority alarm will sound after 1 second and both of these electronic
alarms will continue for 10 seconds after the occlusion is removed
iv) Remove the occlusion.
v) Select 'Air Mix'.
vi) Completely occlude the outlet port and again note the movement of the needle on the
Inflation Pressure Monitor. The needle should this time rise rapidly at first then slower
until the 80 x100Pa (80 cmH
2
O) is reached but with one smooth action. The pneumatic
and electronic alarms should again operate as in 10.2 iii).
vii) If the needle rises jerkily to the 80 x100Pa (80 cmH
2
O) mark, there is a fault within the
air entrainment NRV.
10.3. Check the CMV/Demand Function (200D/220D only)
i) Connect a test mask to the outlet port of the patient valve preferably using a Heat &
Moisture Exchange Filter to provide a contamination barrier, or use a test circuit
complete.
ii) Set the Tidal Volume to 800 mL, the Frequency control to 12 breaths per minute.
iii) After giving the ventilator 4 to 5 breaths to settle down, demand a full single breath at
the end of the expiratory phase. The green Breathing Detect LED (bottom centre)
should illuminate briefly. There should be a short delay and then the ventilator should
deliver a second breath.
iv) Continue to demand full breaths on the ventilator at a rate faster than 12 BPM, which
should inhibit the automatic cycling. For each breath taken the Breathing Detect LED
should illuminate briefly.
v) Stop demanding breaths from the ventilator and it should begin to auto cycle after the
correct expiratory time has elapsed.
vi) Repeat the test but gradually reduce the size of each breath whilst maintaining the rate.
The ventilator should continue to inhibit until the breath taken is too small in flow or
short in time to inhibit. At this point the ventilator should restart auto cycling.
vii) Repeat the test again but this time using short ‘panting’ breaths. The ventilator should
ignore these and continue cycling.
viii) Select the 'Off' or 'Demand' position. Now demand a breath from the ventilator. The
Demand Valve should now supply oxygen to the Patient Valve. No LEDs will
illuminate.
ix) Close the cylinder or supply and continue to demand breaths. When the supply is
depleted, the gas supply indicator should change from white to red and the internal
spontaneous breathing valve should open. There should be a slight increase in
breathing resistance as air is drawn through the spontaneous breathing valve from
atmosphere.
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