In this study, the investigators aim to observe the change in alveolar macrophage function during acute lung injury.

Alveolar macrophages are tissue-resident or recruited cells with key functions in recognition of pathogens, initiation of host defensive ang protective inflammation,and in clearance of pathogens from the airways. However, macrophages are also responsible for efficient clearance of apoptotic neutrophils, termed efferocytosis, which is a prerequisite for the timely resolution of inflammation. In this study, the investigators aim to observe the change in alveolar macrophage function during acute lung injury.

Inclusion Criteria:

• Patients in ICU with diagnosed ALI under mechanical ventilation

Exclusion Criteria:

• Patients with cardiac dysfunction, using steroid drugs or other drugs can that affect efferocytosis

ALI and acute respiratory distress syndrome (ARDS) are characterized by an increased permeability of the alveolar-capillary barrier resulting in lung edema with protein-rich fluid, thus resulting in impairment of arterial oxygenation. ALI/ARDS is defined as a lung disease with acute onset, noncardiac, diffuse bilateral pulmonary infiltrates and a paO2/FiO2 ≤ 300 for ALI or a paO2/FiO2 ≤ 200 for ARDS. The ageadjusted incidence of ALI/ARDS is estimated with 86.2 per 100,000 person-years. Despite all innovations in intensive care medicine, the mortality of ARDS remains up to 40%.

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