Protective lung strategies—low tidal volumes (Vt), increased positive end-expiratory pressures (PEEP) and lower plateau pressures (Pplat)—have been the mainstay of acute respiratory distress syndrome (ARDS) treatment, thought to confer survival benefit by reducing mechanical damage to the lungs. However, strategies can conflict, and the net negative effect of sacrificing one parameter for another is unclear. Because respiratory-system compliance (Crs) is strongly related to the volume of aerated remaining functional lung during disease (termed functional lung size), Amato et al hypothesized that driving pressure (ΔP = Vt/Crs), in which Vt is intrinsically normalized to functional lung size (instead of predicted lung size in healthy persons), would be an index more strongly associated with survival than Vt or PEEP in patients with ARDS who are not actively breathing.
They found that driving pressure was the ventilation variable that best stratified risk. Decreases in driving pressure owing to changes in ventilator settings were strongly associated with increased survival.
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