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
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)
(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)
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