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26.4 Software and System Fail
Protocols
The ventilator has been specifically designed to
minimize the risk of system failure and software
programming error. This has been achieved by
dividing the system into individual subsystems that
can operate independently and manage themselves
via a well defined and robust messaging system.
It is possible for the user interface to fail (Blank
display), and the controller and monitor can
continue to operate normally and ventilate the
patient, although the user would not be able to
change ventilation settings.
Furthermore the entire system is backed up from a
rechargeable internal battery which is periodically
monitored to check its integrity. If the battery is not
detected then an alarm is provided. If the mains
power fails then the system reverts to battery and
an alarm for this condition is displayed. A further
alarm sounder in the power supply itself also
sounds independently of the monitor alarm. The
battery voltage is also monitored during battery use
and a threshold alarm is given when the battery
starts to run low. This allows the patient to be
transferred off the system before all power sources
are exhausted. This also protects the battery from
deep discharge damage.
Alarm 54. Low Oxygen Level
Alarm message ....................Low Oxygen Level
Alarm sub message .............The Oxygen level is
lower than set
Priority of alarm ....................54
Monitor mode .......................All
Can alarm be muted ............Yes
Sounder Priority ...................High
Alarm Description:
If the delivered oxygen differs from the user
selected level by more than 5%, the above alarm
is generated.
Action: Recalibrate O
2
sensor. If alarm re-
appears, remove patient to alternative form of
ventilation, then remove ventilator from
service.
Alarm 55. Monitor/Display Comms Fail
Alarm message ....................Monitor/Display
Comms Fail
Alarm sub message .............Call engineer
Priority of alarm ....................55
Monitor mode .......................All
Can alarm be muted ............No
Sounder Priority ...................High
Alarm Description:
When the ventilator detects a communications
failure between the controller and the monitor/
display system, this alarm is generated.
Action: Remove patient to alternative form of
ventilation, then remove ventilator from
service.
Alarm 56. Alarm Controller Fail
Alarm message ....................System Fail
Alarm sub message .............Alarm Controller Fail
Priority of alarm ....................56
Monitor mode .......................All
Can alarm be muted ............No
Sounder Priority ...................High
Alarm Description:
If the alarm controller fails this message is
generated.
Action: Remove patient to alternative form of
ventilation, then remove ventilator from
service.
Alarm 57. Complete Power Fail Alarm.
Type......................................Audible Only
Can alarm be muted ............No
Alarm Description:
If both mains and battery power fail this alarm is
sounded.
Action: Remove patient immediately to
alternative form of ventilation, then remove
ventilator from service.
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