Airway Pressure Release Ventilation (APRV) Compared to ARDSnet Ventilation

Traditional modes of ventilation have failed to improve patient survival. Subsequent observations that elevated airway pressures observed in traditional forms of ventilation resulted in barotrauma and extension of ALI lead to the evolution of low volume cycled ventilation as a potentially better ventilatory modality for ARDS. Recent multicenter trials by the NIH-ARDS network have confirmed that low volume ventilation increases the number of ventilatory free days and improves overall patient survival. While reducing mean airway pressure has reduced barotrauma and improved patient survival, it has impaired attempts to improve alveolar recruitment. Alveolar recruitment is important as it improves V/Q mismatch, allows reduction in FIO2 earlier, and decreases the risk of oxygen toxicity. Airway pressure release ventilation (APRV) is a novel ventilatory modality that utilizes controlled positive airway pressure to maximize alveolar recruitment while minimizing barotrauma. In APRV, tidal ventilation occurs between the increase in lung volumes established by the application of CPAP and the relaxation of lung tissue following pressure release. Preliminary studies have suggested that APRV recruits collapsed alveoli and improves oxygenation through a restoration of pulmonary mechanics, but there are no studies indicating the potential overall benefit of APRV in recovery form ALI/ADRS.