Alarm Conditions - Delfi PTS ii Operator And Maintenance Manual

2.17 ALARM CONDITIONS
There are a number of conditions for which the PTS ii
will produce visual and audible alarms. Those
conditions, indications and appropriate actions are
shown in Table 2.1. The appropriate actions indicated
are based on the most probable causes and should only
be used as a guide. Other causes of alarm conditions
may indicate a need for other actions.
The alarm indicator light is illuminated and an audible
alarm tone is produced whenever a alarm condition is
detected.
2.20.1 ALARM SILENCE FUNCTION
Most audible alarm tones may be silenced for 30
seconds by momentarily depressing the alarm silence
button which is displayed whenever a silencable alarm
condition is present. At the end of the silenced period,
the alarm tone will restart if the alarm condition has
not been corrected. The alarm tone may be silenced
for additional 30 second periods as required.
2.20.2 PRESSURE HIGH or LOW ALARMS
A "HIGH PRESSURE" or "LOW PRESSURE" alarm will
occur when the pressure in a cuff is more than 15
mmHg from the pressure set point. To minimize
nuisance alarms that can be caused by vigorous
movement of the patient's limbs, a 1 second delay has
been designed into alarm actuation for these
conditions.
2.20.3. LEAK ALARMS
It is possible for the system to have a substantial leak
that the unit can compensate for by continual
pumping. This type of leak could be due to a hole in
the cuff or hose assembly, a loose or worn hose
connector, or leaks in the pneumatic circuit inside the
PTS ii unit. All leaks require immediate attention,
because they could progress into a total failure of a
cuff to hold pressure at any time. To alert the operator
that a substantial leak is present, the "CUFF LEAK"
alarm is activated when this type of leak is continuously
present for more than 7 seconds, even if the unit is
maintaining the cuff pressure within 15 mmHg of the
set point. If a "CUFF LEAK" alarm occurs, the cuff, hose
assembly, and hose connectors should be checked for
leaks. If an external leak cannot be found, test the PTS
ii unit per Section 3.4 below.2.8.2.
2.20.4 INTERNAL HARDWARE FAILURES
When "SYSTEM ERROR" and a numeric error code
appear in the pressure and time displays during use or
power‐up, an internal hardware failure has likely
occurred and the PTS ii unit is unusable. In this
situation, it is likely that the unit has put itself in the
'safe state' mode, in which the pneumatic valve and
pump are disabled and the current pressure in the cuff
is held (in the absence of leaks). It is also likely that a
tone will sound under these conditions. The 'safe
state' mode helps prevent unexpected loss of occlusion
during a procedure if a sudden failure occurs.
Although it is very unlikely, internal hardware failures
may also cause erratic operation and/or unintelligible
displays with or without alarms, and may or may not
put the PTS ii in the 'safe state' mode.
If either type of error occurs:
a) Set the unit to standby by pressing the
'ON/STANDBY' button. This removes power from
the internal instrument circuitry and all instrument
functions, causing the cuff to hold pressure (in the
absence of leaks).
b) If required, attempt to restart the unit by pressing
the 'ON/STANDBY' again to restart the unit.
c) If required to continue the procedure, clamp the
hose with a hemostat to maintain cuff pressure,
then immediately disconnect the faulty PTS ii unit
and connect a replacement unit.
d) If cuff deflation is required, disconnect the cuff
from the PTS ii unit.
WARNING
: In all cases of internal hardware failure,
erratic operation, or unintelligible displays, it is
possible that the pressure in the cuff is not accurately
displayed on the PTS ii unit and that cuff pressure
may be present even when the PTS ii unit appears to
be shut down. The user must immediately determine
if the cuff is inflated or deflated and continually
monitor the cuff to ensure patient safety. If deflation
of the cuff is necessary, disconnect the hose from the
PTS ii unit or from the cuff and confirm that the cuff
deflates completely.
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