Extravascular lung water predicts progression to acute lung injury in patients with increased risk

Objectives: To compare the extravascular lung water index and other markers of disease severity in patients with acute lung injury vs. patients at risk for development of acute lung injury and to determine their ability to predict progression to acute lung injury in patients at risk. Design: Extravascular lung water index, dead space fraction, Pao(2)/Fio(2), and other markers of disease severity were measured prospectively in 29 patients daily for 5 days after admission to the intensive care unit. Patients had acute lung injury as defined by the American European Consensus Committee criteria or had risk factors for development of it. Setting: The intensive care units of an academic tertiary referral hospital. Measurements and Main Results: The mean extravascular lung water index on day 1 for patients who progressed to acute lung injury was higher than for those who did not (15.5 +/- 7.4 mL/kg vs. 8.7 +/- 2.3 mL/kg; p = .04). None of the other physiologic parameters tested discriminated progression to acute lung injury to include the mean physiologic dead space (0.61 +/- 0.06] vs. 0.59 +/- 0.10; p = .67), Pao(2)/Fio(2) ratio (322 +/- 35 vs. 267 +/- 98; p = .15), and static lung compliance (30.9 +/- 13.5 vs. 38.5 +/- 11.7; p = .24). An extravascular lung water index cutoff value on day 1 of 10 mL/kg had a 63% sensitivity, 88% specificity, positive predictive value of 83%, and negative predictive value of 70% to predict progression to acute lung injury. There was no difference in extravascular lung water index between those who progressed to acute lung injury vs. those who had acute lung injury (14.3 +/- 4.7 vs. 15.5 +/- 7.4; P = .97). Conclusions: Elevated extravascular lung water index is a feature of early acute lung injury and discriminates between those with acute lung injury and those without. Furthermore, extravascular lung water index predicts progression to acute lung injury in patients with risk factors for development of acute lung injury 2.6 +/- 0.3 days before the patients meet American European Consensus Committee criteria for it. These 2.6 +/- 0.3 days may then represent missed opportunity for therapeutic intervention and improved outcome. (Crit Care Med 2012; 40:847-854)