To investigate the possible mechanisms of pulmonary and systemic permeability change including cytokine, extravascular lung water index (EVLWI), and oxygenation parameters in patients with sepsis related acute lung injury (ALI)/acute respiratory distress syndrome (ARDS).

This investigation is a prospective control study. Informed consents will be obtained from all patients or their surrogates prior to the procedure of EVLWI measurement and blood sampling for molecular measurement including cytokines.

From July 2011 to June 2014, consecutive septic patients with ARDS in intensive care units (ICUs) will be enrolled at Chang Gung Memorial Hospital, a university-affiliated hospital in Taiwan. EVLWI will be measured by PiCCO monitoring system. Serum cytokine such as endothelin-1, TNF-alfa, IL-6, Tie-1, Tie-2, angiopoietin-1, angiopoietin-2,VEGF and thrombomodulin will be measured.

Inclusion Criteria:

• sepsis in ICU within 48 hours,
• mechanical ventilator use,
• PaO2/FiO2 < 300,

Exclusion Criteria:

• age younger than 20 years,
• known pregnancy,
• participation in another trial within 30 days before meeting the eligibility criteria, and
• terminal malignancy.

Septic patients receiving endotracheal mechanical ventilation for hypoxemic acute respiratory failure were eligible if the following criteria were met for no more than 48 hours before enrollment: ratio of partial pressure of arterial oxygen over fraction of inspired oxygen (PaO2:FIO2) no greater than 300 mm Hg at time of enrollment, recent appearance of bilateral pulmonary infiltrates consistent with edema, and no clinical evidence of left atrial hypertension (pulmonary-capillary wedge pressure _18 mm Hg, when available).