Extravascular lung water in sepsis-associated acute respiratory distress syndrome: Indexing with predicted body weight improves correlation with severity of illness and survival*

Abstract

Objectives: To determine whether extravascular lung water predicts survival in patients with early acute respiratory distress syndrome, to determine the relationship between extravascular lung water and other markers of lung injury, and to examine if indexing extravascular lung water with predicted body weight (EVLWp) strengthens its discriminative power. Design: Extravascular lung water and other markers of lung injury were measured prospectively in 19 patients with sepsis-induced acute respiratory distress syndrome for 3 days. Setting: The intensive care units of an academic tertiary referral hospital. Measurements and Main Results: Lung injury score, Sequential Organ Failure Assessment score, dead space-tidal volume fraction (Vd/Vt), and EVLWp were all significantly higher on day 1 in nonsurvivors compared with survivors (lung injury score, 2.8 ± 0.34 vs. 1.9 ± 0.50; p = .004) (Sequential Organ Failure Assessment score, 13 ± 3.4 vs. 7.7 ± 0.8; p = .006) (Vd/Vt, 0.68 ± 0.07 vs. 0.58 ± 0.07; p = .009) (EVLWp, 20.6 ± 4.6 vs. 11.6 ± 1.9 mL/kg; p = .002). EVLWp correlated with Sequential Organ Failure Assessment score, lung injury score, Vd/Vt, and Pao2/Fio2. The receiver operator characteristic curve analysis indicated that EVLWp, Vd/Vt, and extravascular lung water (p = .0005, .009, and .013, respectively) but not Pao2/Fio2 (p = .311) discriminate between survivors and nonsurvivors. Three-day average EVLWp >16 mL/kg predicted in-hospital mortality with 100% specificity and 86% sensitivity. Conclusions: Increased extravascular lung water is a feature of early acute respiratory distress syndrome and predicts survival. Indexing extravascular lung water to predicted body weight, instead of actual body weight, improves the predictive value of extravascular lung water for survival and correlation with markers of disease severity.