Astral Disconnection Alarm; Adjusting The Disconnection Alarm; Setting And Testing Disconnection Tolerance - ResMed Astral Series Clinical Manual

Astral Disconnection Alarm

Astral Disconnection Alarm
The Astral Disconnection Alarm constantly measures circuit resistance to calculate the degree of
disconnection (displayed as a percentage). The high priority Disconnection Alarm will activate when the
measured disconnection value is greater than the set tolerance for the alarm Activation Time.
The alarm will only activate if the measured disconnection value is continuously above the Disconnection
Tolerance for the alarm Activation Time. If the monitored value drops below the set Disconnection
Tolerance during this time, the time to alarm activation will reset.
The alarm will not activate if patient expiratory effort is detected, indicated by the symbol below the
measured Disconnection value.
Any active alarm will clear when the monitored value drops below the set Disconnection Tolerance.

Adjusting the Disconnection Alarm

There are three settings that can be adjusted to the Disconnection Alarm to suit patient needs:
1. Disconnection Tolerance – to set a higher or lower tolerance to activate the Disconnection Alarm
2. Alarm Activation Time – the time it takes (in seconds) following disconnection for the alarm to
activate
3. Disconnection Alarm On/ Off (selected interfaces only).
CAUTION
Be certain that patient disconnection can be detected, including if the patient interface becomes
accidentally detached from the patient (eg, if the tracheostomy tube / endotracheal tube / mask /
mouthpiece remains attached to the circuit). For example, to check that accidental decannulation
of a tracheostomised patient can be detected, simulate disconnection using a tracheostomy tube
one size smaller than the patient's tube.
Refer to Testing the disconnection alarm on page 113.

Setting and testing Disconnection Tolerance

The Disconnection Tolerance threshold represents how 'leaky' a circuit can be -- or degree of
'disconnection' -- before the Disconnection Alarm is asserted. Disconnection Tolerance is adjustable from
5% (little 'disconnection' will be tolerated before alarm) through to 95% (large degree of 'disconnection'
tolerated without alarm).
To assist with alarm adjustment, leakage from the circuit is continuously measured and displayed after
each breath. The measured value is scaled to permit direct comparison against the Disconnection
Tolerance adjustment range. A measured value greater than or equal to the configured Disconnection
Tolerance will be displayed in red, along with an icon depicting a 'disconnected' circuit. If this level of
leakage from the circuit were sustained for the Activation Time, the alarm would assert.
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