Airway Pressure Release Ventilation (APRV)

Cyclical changes in lung volume from standard mechanical ventilation causes lung injury, ideally, patients would be ventilated with full alveoli.
The longer the inspiratory time, the better the oxygenation. If inspiratory time becomes greater than expiratory time, then CO2 will build up. In APRV, patients baseline is a high PEEP level. Intermittently, this level is released to a lower peep level to allow expiration. Bilevel Ventilation or BIPAP (not BiPAP™) are synonymous c APRV

Compliance of Tubing

The compliance of regular tubing is greater than the lungs of patients with high APRV settings/ARDS, so tubing will absorb some of the pressure, must change to non-compliant tubing

APRVarticle by Nader (Curr Opin Crit Care 2004;10:549)

Better Habashi article (Crit Care Med 2005;33(3S):S228)

 
Address patient sedation

(tachypnea in PSV is often from inadequate sedation)
Beware of tachypnea with small tidal volumes

Review article on the benefits of spont breathing in APRV (Crit Care 2005;10(1):102)

and another (Curr Opin Crit Care 2006;12:13)

Using APRV vent for HFV

achieves RR of 60
set Ti 0.6 seconds
set Te 0.4 seconds
set Pressure High 40-50 (adjust per MAP goal, watch for BP drop on initiation---if such occurs reduce and/or add preload if such a “gauntlet” does the trick)
Rise Time 100%
set Pressure Low 0

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