Ventilation Strategies for Acute Lung Injury and Acute Respiratory Distress Syndrome

To the Editor: The study of PEEP settings in adults with ALI and ARDS by Dr Mercat and colleagues¹ did not find a mortality benefit in patients in the increased recruitment (high-PEEP) group compared with patients in the minimal distension arm. Lungs of patients with ARDS are likely to be less compliant, with resulting higher plateau pressures during volume-controlled ventilation.^2- 3 In the increased recruitment group, patients with ARDS, compared with patients with less ALI and more compliant lungs, would receive lower levels of PEEP at the target plateau pressure of 30 cm H₂O. This PEEP level may have been close to that applied in the minimal distension group in which the PEEP level was restricted between 5 and 9 cm H₂O. It is therefore possible that in patients with severe forms of lung injury, there may not have been meaningful differences between the actual PEEP levels achieved in the 2 groups. A protocol that required the PEEP level to be decreased with increasing severity of lung injury may have diluted the potential benefit of “high” PEEP in the increased recruitment group.