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Chapter 3: Ventilator Operation
Operator's manual
Airway Pressure Release Ventilation (APRV / BIPHASIC)
APRV / BiPhasic is a Time Cycled Pressure mode in which the ventilator cycles between two different baseline
pressures based on time, which can be synchronized with patient effort. Controlled ventilation can be maintained by
timed cycling the transitions between baseline pressures. Additionally, pressure support can be added to improve
comfort for the spontaneous breathing patient.
In this mode, the patient is allowed to breathe spontaneously at two preset pressure levels. These are set using the
Pres High and Pres Low controls. The maximum duration at each pressure during time cycling is set with the Time
High and Time Low controls.
The operator can also adjust the length of the respective trigger (Sync) windows with the Time High and Time Low Sync
controls, which are advanced settings of Time High and Time Low. The Sync windows are adjustable from 0 to 50%, in
5% increments of set Time High and Time Low.
The ventilator synchronizes the change from Pressure Low to Pressure High with the detection of inspiratory flow or the
first inspiratory effort detected within the T Low Sync window. Transition from Pressure High to Pressure Low occurs
with the first end of inspiration detected after the T High Sync window opens.
Note:
Time High and Time Low are maximum time settings for a time-cycled transition. Actual times may vary depending on
the patient's spontaneous breathing pattern and the Sync window setting.
Setting the Sync to 0% cycles the transition between pressure levels on time only and will not provide synchronization
with patient efforts.
The Manual Breath button is not active in APRV / BiPhasic.
The monitored PEEP in APRV/BIPHASIC is relative to the breath type. In the absence of spontaneous breathing, the
monitored PEEP will be the Pressure Low. In the presence of spontaneous breathing the monitored PEEP will reflect
the baseline pressure over which spontaneous breathing is occurred.
Adjustable PSV in APRV / BiPhasic
APRV / BiPhasic features adjustable PSV. The PSV is delivered above the current phase baseline pressure. PSV
breaths are available during Time High also, by activating T High PSV (an advanced setting of Time High). If T High
PSV is activated, during Time High, the ventilator will deliver the same PSV level for both Pressure Low and Pressure
High.
Note:
The ventilator will not allow the operator to set a Peak Inspiratory Pressure (Insp Pres or PSV + PEEP, or baseline
pressure in APRV / BiPhasic, greater than 90 cmH
O). The ventilator will deliver an on screen Pop-Up Message stating
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that the Ppeak > 90 cmH
O. The operator must change the Inspiratory Pressure and or PEEP setting to limit the Ppeak
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to less than or equal to 90 cmH
O. This 90 cmH
O limit warning is not active when T High PSV is OFF.
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L2786 Rev. M
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Troubleshooting
