RESUMO
OBJECTIVE: To observe and evaluate the pathophysiological indexes of acute lung injury (ALI) induced by lipopolysaccharide (LPS) in rats. METHODS: Thirty-three Wistar rats were randomly divided into normal control group and experiment group. Respiratory rate , mortality, arterial blood gases, compliance and wet weight of right lung/body weight ratio, tumor necrosis factor-alpha (TNF-alpha) in serum and bronchoalveolar lavage fluid (BALF) were determined 2, 4 and 6 hours after injection of LPS or normal saline in both groups. RESULTS: In the experiment group,the following changes were found. Arterial partial pressure of oxygen (PaO(2)) was reduced to 69.18 mm Hg (1 mm Hg=0.133 kPa), marked blood stasis, and edema in lung tissues could be grossly seen and pathological examination showed that there was a large number of inflammation cell infiltration and edema in interstitial spaces with disappearance of normal construction of alveolar. There was also dilatation of capillaries with congestion and adherent leukocytes. Furthermore, compliance was decreased to 47% of the normal value, and wet weight of right lung/body weight ratio increased to 137% of the normal value. Blood TNF-alpha level increased markedly in serum and BALF. CONCLUSION: Specific pathological changes and decreased PaO(2) over 30% of the baseline value are the main signs of successful reproduction of ALI model in rats. Compliance and weight of right lung/body weight value can also reflect the status of ALI as helpful indexes.