Design: Systematic review and meta-analysis of 9 randomised trials
Population: 585 adults with or at risk of ARDS
Primary outcome: Mortality at trial-defined follow-up
Effect: RR 0.95 (95% CI 0.72–1.26); PaO2/FiO2 +56 mmHg (24.6–87.8)

This meta-analysis pooled nine randomised trials with 585 adults who had, or were at high risk of, ARDS, comparing airway pressure release ventilation (APRV) with conventional ventilation.

Mortality did not differ (RR 0.95). Ventilator-free days and ventilation duration showed no clear difference. APRV raised the PaO2/FiO2 ratio by about 56 mmHg and was associated with an ICU stay about 2.5 days shorter, but heterogeneity was high and certainty low to very low.

APRV keeps the lung open with a long high-pressure phase and brief releases. Better oxygenation is expected from higher mean airway pressure; it has not translated into survival in any convincing trial.

The trials were small, used varied protocols and did not always compare against modern lung-protective ventilation. This does not support APRV as a default.

Keep low tidal volume, pressure-limited conventional ventilation as the default in ARDS.
Do not switch to APRV expecting a survival benefit.
If APRV is used as rescue, monitor tidal volumes during releases, which can exceed protective limits.
Judge ventilation strategies by survival and ventilator-free days, not oxygenation alone.

Why it matters

A better blood gas is not the same as a patient who survives.

The statistics, in plain English

A risk ratio of 0.95 with a confidence interval of 0.72 to 1.26 includes both meaningful benefit and harm, so the trials cannot tell. I² values above 70% mean the trials disagreed considerably on secondary outcomes.