Tidal volume and plateau pressure use for acute lung injury from 2000 to present: a systematic literature review.

OBJECTIVE: Since publication of the Respiratory Management of Acute Lung Injury and Acute Respiratory Distress Syndrome (ARMA) trial in 2000, use of tidal volume (VT) less than or equal to 6 mL/kg predicted body weight with corresponding plateau airway pressures (PPlat) less than or equal to 30 cm H2O has been advocated for acute lung injury. However, compliance with these recommendations is unknown. We therefore investigated VT (mL/kg predicted body weight) and PPlat (cm H2O) practices reported in studies of acute lung injury since ARMA using a systematic literature review (i.e., not a meta-analysis). DATA SOURCES: PubMed, Scopus, and EMBASE. STUDY SELECTION: Randomized controlled trials and nonrandomized studies enrolling patients with acute lung injury from May 2000 to June 2013 and reporting VT. DATA EXTRACTION: Whether the study was a randomized controlled trial or a nonrandomized study and performed or not at an Acute Respiratory Distress Syndrome Network center; in randomized controlled trials, the pre- and postrandomization VT (mL/kg predicted body weight) and PPlat (cm H2O) and whether a VT protocol was used postrandomization; in nonrandomized studies, baseline VT and PPlat. DATA SYNTHESIS: Twenty-two randomized controlled trials and 71 nonrandomized studies were included. Since 2000 at acute respiratory distress syndrome Network centers, routine VT was similar comparing randomized controlled trials and nonrandomized studies (p = 0.25) and unchanged over time (p = 0.75) with a mean value of 6.81 (95% CI, 6.45, 7.18). At non-acute respiratory distress syndrome Network centers, routine VT was also similar when comparing randomized controlled trials and nonrandomized studies (p = 0.71), but decreased (p = 0.001); the most recent estimate for it was 6.77 (6.22, 7.32). All VT estimates were significantly greater than 6 (p ≤ 0.02). In randomized controlled trials employing VT protocols, routine VT was reduced in both acute respiratory distress syndrome Network (n = 4) and non-acute respiratory distress syndrome Network (n = 11) trials (p ≤ 0.01 for both), but even postrandomization was greater than 6 (6.47 [6.29, 6.65] and 6.80 [6.42, 7.17], respectively; p ≤ 0.0001 for both). In 59 studies providing data, routine PPlat, averaged across acute respiratory distress syndrome Network or non-acute respiratory distress syndrome Network centers, was significantly less than 30 (p ≤ 0.02).
CONCLUSIONS: For clinicians treating acute lung injury since 2000, achieving VT less than or equal to 6 mL/kg predicted body weight may not have been as attainable or important as PPlat less than or equal to 30 cm H2O. If so, there may be equipoise to test if VT less than or equal to 6 mL/kg predicted body weight are necessary to improve acute lung injury outcome.