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
CONCLUSIONS: PEEPi varied significantly among ventilators. Inspiratory and expiratory work ofbreathing varied between ventilators when spontaneous breathing occurred during the ventilatorsinspiratory phase. (Anesth Analg 2011;113:52933)
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