Extravascular lung water indexed or not to predicted body weight is a predictor of mortality in septic shock patients

Abstract

Purpose: The purpose was to investigate whether extravascular lung water (EVLW) indexed to actual body weight (EVLWa) is an independent predictor of mortality in patients with septic shock, to determine the relationship between EVLWa and other markers of lung injury, and to test if indexing EVLW with predicted body weight (EVLWp) strengthens its predictive power.

Methods: Extravascular lung water, pulmonary vascular permeability index, and other markers of lung injury were measured prospectively in 55 patients with septic shock for 3 days.

Results: At day 1, EVLWa, EVLWp, and pulmonary vascular permeability index were not significantly different between survivors and nonsurvivors. However, in parallel to the course of septic shock, these variables decreased only in the survivors and remained elevated in the nonsurvivors, reaching intergroup difference by day 3. In multiple logistic regression analysis, both EVLWa and EVLWp (at day 3) were predictors of mortality with an odds ratio of 2 (95% confidence interval, 1.12-3.7) and 1.7 (95% confidence interval, 1.1-2.5) per SD increase, respectively. The receiver operating characteristic curve analysis showed that EVLWp did not improve the discriminative power of EVLW to predict mortality. Extravascular lung water indexed to actual body weight correlated with lung injury score and with the ratio of arterial oxygen partial pressure to inspired oxygen fraction but not with static respiratory compliance. Indexing EVLW to predicted body weight did not ameliorate these correlations.

Conclusions: Extravascular lung water indexed or not to predicted body weight is an independent predictor of mortality in patients with septic shock. Repeated measurements of EVLW indexes over time, rather than a too-early measurement, seem to be more appropriate for predicting outcome.