Higher vs Lower Positive End-Expiratory Pressure in Patients With Acute Lung Injury and Acute Respiratory Distress Syndrome: Systematic Review and Meta-analysis
Briel M, Meade M, Mercat A, et al
Debate about the optimal way to set positive end-expiratory pressure (PEEP) in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) continues, because existing studies have not been sufficiently large to detect small differences. The investigators sought to resolve this clinical query by conducting a systematic review of the existing research in which patients with ALI or ARDS were randomly assigned to higher vs lower PEEP levels and mortality was reported. Among 1136 patients in 3 trials, death occurred in 32.9% of patients assigned to treatment with higher PEEP and in 35.2% of patients assigned to lower PEEP with a nonsignificant adjusted relative risk (RR) of 0.94 (P = .25). In the more severely hypoxemic patients with ARDS (n = 1892), death occurred in 34.1% of patients in the higher PEEP group and in 39.1% of patients the lower PEEP group (adjusted RR = 0.90; P = .049). Overall, rates of pneumothorax and vasopressor use were similar between groups. The investigators concluded that treatment with higher levels of PEEP was associated with improved survival only among the subgroup of patients with ARDS.
Low tidal volume ventilation has become the standard in lung protective ventilation for treating patients with ALI or ARDS.This has been shown to reduce the development of ventilator-induced lung injury.[2,3]Knowing the optimal level of PEEP would help to further reduce ventilator-induced lung injury by preventing alveolar injury from cyclic opening and closing. This study provides a better understanding of how to set PEEP for patients with ALI or ARDS, and it appears that higher levels of PEEP may benefit the more severely hypoxemic patients (eg, those with ARDS). However, this study also found that the risk for death among the less severely hypoxemic patients (eg, patients with ALI and a ratio of partial pressure of oxygen to fraction of inspired oxygen between 200 and 300 mm Hg) was increased when treated with higher PEEP (27.2% vs 19.4%, P = .07). This finding makes application of these results difficult, particularly because ARDS invariably begins with ALI, and most patients in whom ALI develops ultimately experience progression to ARDS and then (presuming they recover) transition back to ALI before their hypoxemia resolves. In addition, the dynamic nature of ALI and ARDS and individual patient heterogeneity make it unlikely that any given level of PEEP (high or low) is appropriate in all circumstances.
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Cite this: Gregory S. Martin. High vs Low Positive End-Expiratory Pressure in Ventilatory Management of Adults - Medscape - Apr 23, 2010.