Datex-Ohmeda Anesthesia Delivery Unit S/5, Technical Reference Manual

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Technical description A-EV1
Document No. 8502855
C-9
The ventilator will go to safe state and send the message pressure compare error to main SW if the
differences between the Monitor and Circuit pressures are outside allowed limits.
•
Difference > 6.5 cmH
2
O for pressures over 55 cmH
2
O
•
Difference > 5.5 cmH
2
O for pressures over 25 cmH
2
O
•
Difference > 4.0 cmH
2
O otherwise.
Bellows chamber pressure sensor
The bottle pressure sensor is used for:
•
Cutting the inspiration if bellows reach the bottom
•
Measure pilot pressure during ventilator self test or manually by service diagnostics
•
Initiate the alarm Fill Bellows. This is done by comparing the patient pressure with the chamber
pressure value. In principal - if the chamber pressure is higher that the patient pressure, the
Inspiration interrupt and alarm are initiated. The table below describes the triggering limits for
the alarm Fill Bellows.
Gas consumption
In volume controlled mode the ventilator´s gas consumption is roughly the same as the patient
minute volume plus the waste fresh gas flow during expiration.
In PCV mode the ventilator will have higher gas consumption depending of set pressure, IE ratio and
flow.
As the compressed volume of the circuit is added to the volume delivered by the ventilator it should
be included in the gas consumption. E.g. when the compliance of circuit is 4 ml/cmH
2
O and the
circuit pressure is 15 cmH
2
O, the lost volume for each inspiration is 60 ml. If the ventilation rate is 12,
the extra gas consumption is 720 ml/min.
The PEEP function increases the gas consumption with the amount of the support flow. The required
support flow is about 10 l/min. As the consumption only increases during the expiration, it is
dependent of the I:E ratio setting.
Measuring sensors
The sensors are pressure sensors.
The chart below shows the sensors and their zeroing functions.
Patient peak pressure Allowed pressure difference
(chamber pressure – patient pressure)
lower than 5.5 cmH
2
O difference < 0.5 cmH
2
O
lower than 15 cmH
2
O difference < (peak pressure – 5.0)
otherwise difference < 10 cmH
2
O
Sensors and
measuring
Name on
diagnostic
page
Measuring
range
Zeroing
Patient circuit Circuit -40 - 100 cmH
2
O zeroing valve 2 (zero phase 1 or 2)
Patient circuit (monitoring) Monitor -40 - 100 cmH
2
O zeroing valve 1 (zero phase 1 or 2)