ARDS · What ventilator variable matters
Driving pressure and survival in the acute respiratory distress syndrome
| Design | Multilevel mediation analysis of individual patient data from nine previous randomised trials |
|---|---|
| Treatment | Lower driving pressure (plateau pressure minus PEEP) |
| Control | Higher driving pressure |
| Population | 3562 patients with ARDS pooled from nine randomised trials |
| Follow-up | As per contributing trials |
| Primary endpoint | Association between ventilator variables and survival |
| Result | Driving pressure was the ventilation variable most strongly associated with survival. A one-standard-deviation increment of about 7 cmH2O was associated with increased mortality (relative risk 1.41, 95% CI 1.31 to 1.51, p<0.001), and this held even in patients receiving protective plateau pressures and tidal volumes (relative risk 1.36, 95% CI 1.17 to 1.58, p<0.001). |
| Secondary endpoints | Relative contribution of tidal volume and PEEP |
We found that ΔP was the ventilation variable that best stratified risk. Decreases in ΔP owing to changes in ventilator settings were strongly associated with increased survival.
The trial authors, in the published abstract
An analysis, not a trial — it can identify the variable that stratifies risk but cannot show that targeting it saves lives, and no adequately powered trial has yet done so. It nonetheless reframed lung-protective ventilation around the pressure the lung actually experiences rather than the volume delivered, and explains why the PEEP trials (ALVEOLI, LOVS, ExPress) were neutral: they changed PEEP without reliably changing driving pressure.
Amato MB, Meade MO, Slutsky AS, et al. Driving pressure and survival in the acute respiratory distress syndrome. N Engl J Med 2015 Feb 19;372(8):747-55.