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

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Datex-Ohmeda ADU
C-68
Document No. 8502855
In VCV mode with a set PEEP it may be observed that the pressure curve has an extra pressure rise
just before the expiration phase starts (see figure below). If the pressure rise is above 1cmH
2
O will
the problem be treated by:
1.
Check that the expiration valve unit membrane suffices side (the side against the seat) is dry
and without any grease. If the membranes feels little sticky can lime be rubbed in on the
membranes surfaces. After this should the membrane surfaces be bleed with air to remove all
loose particles from the lime. Reinstall the membranes to the expiration valve unit and
calibrated the PEEP following up with System Checkout.
2. Replace the membranes in the expiration valve unit and calibrated the PEEP following up with
System Checkout.
Figure 41 Pressure curve
Description of ventilator self test
Electronics checks
When the ventilator starts working, the start-up code is executed. The code consists of checks and
initialisations.
Before any tests, there is a check if the ADU has been reset or properly switched on. If there has been
a reset, a program sets the unit in a safe state, immediately indicated by the alarm ‘Ventilator failure’.
If the ADU has been properly switched on, the operation of the most important electronic
components is checked.
Before any commands are accepted, the software version is checked between the main CPU and the
ventilator. Without the correct handshake, the system goes into safe state.
The electronics checks in order
1. HW-watchdog check
2. memory read and write check
3. program check sum
4. EEPROM value check
5. Memory is zeroed and interrupts initialized.
6. Valve exercise
The zeroing valves and both expiration valves has been implemented at start-up of the Ventilator to
increase the robustness of the self-test. The reason for this is that if an ADU has been out of use for a
prolonged period of time, there is a risk for sticking valves that can cause start-up problems of the
Ventilator during the self-test.
Exercising the zeroing valves will cause a rapid audible clicking sound during self-test. This
distinguishes version 7.6 from prior versions of software. Although it may seem unusual at first, it is
not a fault. The new self-test will take a total time of 70 seconds to execute.