[Experimental study of glucocorticoid in the treatment of acute respiratory distress syndrome induced by E.coli].

Objective: To evaluate the effect of glucocorticoid (GC) in the treatment of septic acute respiratory distress syndrome (ARDS).

Methods: ARDS model was reproduced by intraperitoneal injection of E.coli in piglets. Nine male piglets were randomly divided into control (C group), early (GC1) and middle (GC2) stage treatment groups. In the latter two groups methylprednisolone 20 mg was intravenously,given every 12 hours (4 mg(-1)xkg(-1)xd(-1)). All of the clinical data and survival time during 72 hours were collected and analyzed, including the collection of bronchioalveolar lavage fluid (BALF) for the determination of total protein (TP), total phospholipids (TPL), disaturated phosphatidyl choline (DSPC), and measurement of alveolar tension. Ratio of pulmonary wet and dry(W/D) weight was determined routinely, and pathological changes and their severity were evaluated by optical microscope and Smith scores.

Results: ARDS model was reproduced at (8.3+/-8.5) hours, and survival time of three groups was (11.0+/-6.6) hours, (35.3+/-12.5) hours and (52.5+/-13.8) hours respectively. Animals in GC1 and GC2 survived longer than those in C group, but there was no statistically significant difference among them (both P>0.05).Oxygen index (PaO(2)/FiO(2)) and mean arterial pressure (MAP) were improved in GC1 much better than those of controls (both P<0.05), and the same was true in GC2 as compared that before GC treatment (P<0.05 or P<0.01). There were no significant differences among TPL, DSPC, white blood cell count (WBC) of BALF in each group, so were lung surface tension and W/D (all P>0.05). TP of BALF was significantly higher in GC1 than that in GC2. Compared with C group, alveolar and interstitial edema, inflammation and hemorrhage were more severe in GC1 (all P<0.01), hyaline membrane was less(P<0.01) and no difference in atelectasis (P>0.05). The alveolar and interstitial edema and inflammation in GC2 were more severe than in C group(all P<0.01), and there was no difference in hemorrhage and hyaline membrane formation (both P>0.05).

Conclusion: GC might improve hypoxemia and septic shock as a result of septic ARDS. But the treatment has no influence on pulmonary surfactant (PS), surface tension and lung pathology of ARDS in piglets challenged with intraperitoneal E.coli.