Here is a new CCJM review on airway pressure release ventilation (APRV). Though around for many years it is infrequently used and has not been subject to high level clinical studies. Because it has the potential to recruit alveoli and improve oxygenation over conventional modes, and because it has not been validated as a standard modality of care for ARDS in population based studies, it can be considered a rescue mode.
The article does an excellent job of explaining APRV and is worth reading in full, although I have to disagree with one statement (my emphasis):
Based on these studies, the use of low tidal volumes with appropriate levels of PEEP to ensure lung recruitment is the current standard of care in mechanical ventilation of patients with ARDS.
Again, while recruitment level PEEP may be life saving in cases of ARDS with unusually refractory hypoxemia, it proved to be no better overall than standard PEEP (minimum needed to oxygenate patients using non-toxic fractions of inspired oxygen) in the second ARDSnet trial.