Synopsis: Three randomized-controlled trials eligible for this review included 2,299 critically ill adults with acute lung injury, as defined by the American-European Consensus Conference. The meta-analysis compared higher and lower PEEP levels with a mean difference of at least 3 cm H2O, incorporated a target tidal volume of less than 8 mL/kg of predicted body weight in both ventilation strategies, and provided patient follow-up until death or for at least 20 days.
This review demonstrated no statistically significant difference in hospital mortality between the groups. However, in patients with ARDS, higher levels of PEEP were associated with a relative reduction in mortality of 10%. This is supported by a recent cohort study in patients with acute lung injury or ARDS, which showed that the effect of PEEP on lung recruitment was associated with the proportion of potentially recruitable lung, as determined by computed tomography.
Since patients with ARDS have more pulmonary edema than those with acute lung injury without ARDS, the former have greater recruitability, and thus might benefit more from higher levels of PEEP.
Bottom line: Higher levels of PEEP might be associated with lower hospital mortality in patients with ARDS, but such a benefit is unlikely in patients with less severe lung injuries, and could actually be harmful.
Citation: Briel M, Meade M, Mercat A, et al. Higher vs lower positive end-expiratory pressure in patients with acute lung injury and acute respiratory distress syndrome: systematic review and meta-analysis. JAMA. 2010;303(9):865-873. TH