Objective   To compare the differences between acute lung injury (ALI) induced by seawater-immersion and freshwater-immersion after open chest trauma.   Methods   Twenty-four dogs were randomly divided into 3 groups

ALI model group (control)

seawater immersion group (group SW)

and freshwater immersion group (group FW). ALI model was established by cutting an incision of 0.5 cm at the 4th intercostal space. Then artificial seawater or pure water (35 ml/kg) was perfused into the incision for the later 2 groups. The pathological changes were evaluated by light microscopy

hemotoxin and eosin (HE) staining in 8 h after perfusion. In 0

2

4

6 and 8 h after trauma

the plasma samples were collected to test the levels of IL-1β

IL-8 and von Willnbrang factor (vWF) with ELISA. The amount of total protein in plasma and bronchoalveolar lavage fluid (BALF) were measured.   Results   Compared with group FW

the pulmonary penetration index

the concentrations of IL-1β

IL-8 and vWF in the plasma and lung tissue in group SW were markedly higher. They were significantly positively correlated with the plasma osmotic  pressure  (P0.05).   Conclusion   Despite immersing in seawater and in freshwater worsen the ALI after open chest trauma

the ALI induced by seawater-immersion is severer than that caused by freshwater-immersion. It is attributed to higher plasma osmo-tic pressure and abundance of salts after seawater immersion

which increasing the pulmonary penetration index and aggravating the inflammatory response.