Abstract： Objective To investigate and compare the change of extravascular lung water (EVLW) and levels of cytokines in septic patients without clinical acute lung injury (ALI) /acute respiratory distress syndrome (ARDS) with those in spetic patients with sepsis-induced ALI/ARDS in order to determine the role of EVLW involved in the pathogenesis of lung injury in the patients by quantifying the relationship between EVLW and biomarkers of lung injury in patients with sepsis.Methods A total of 40 septic patients complicated either with or without clinical ALI/ARDS after sepsis. In each patient,transpulmonary thermodilution (PiCCO) was used to measure cardiovascular hemodynamics and EVLWI for 7 days via an arterial cannula indwelled within 72 hours after diagnosis of severe sepsis was made, and serial bronchoalveolar lavages (BAL) were carried out.Other examinations including blood gas analysis,ventilator parameters,chest X-ray and the levels of pro-inflammatory cytokines such as tumor necrosis factor (TNF-oα),interleukin-1 in the BAL were recorded.In-hospital and ICU mortalities were also observed.Results Of total 40 patients,29 were complicated with clinically defined septic ALI/ARDS ( ARDS n =15,and ALI n =14).The septic patients complicated with ALL/ARDS had significantly higher amount of EVLWI and higher levels of TNF-α and interleukin-1 in the BAL than patients without ALI/ARDS ( P ＜ 0.05).The arterial oxygen tension/fractional inspired oxygen ratio,lung injury score,and the levels of TNF-α,IL-1 in the BAL correlated with EVLWI.Moreover,in-hospital mortality,ICU mortality and the length of ICU stay of the patients with high amount of EVLWI were markedly increased than those of patients with low amount of EVLWI. Conclusions In septic patients complicated with ALI/ARDS, the extravascular lung water index correlates with oxygenation,lung injury severity and inflammatory cytokines in lung.Determination of EVLWI may be useful for evaluation of severity of lung injury and prognosis of septic patients.