The Effect of Surfactant Treatment for Experimental Escherichi coli Pneumonia in Rats

ABSTRACT

PURPOSE: Recently, it has been reported that the disease with secondary surfactant deficiency such as pneumonia and adult respiratory distress syndrome (ARDS) improved in arterial blood gas analysis and pulmonary mechanics by surfactant treatment. In this study, we investigated the effect of surfactant in the experimentally induced E. coli pneumonia in rats. METHODS: 0.25 mL (0.5x109) E. coli suspension was injected intratracheally to the rats. After ventilating rats for 1 minute, 0.25 mL Surfactant TA (60 mg/mL phospholipid) was administered to the study group and normal saline to the control group. In about 12 hours, pneumonia symptoms developed, and the arterial blood gas analysis was performed with the blood obtained from abdominal aorta accessed by laparotomy. And then, bronchial lavage fluid (BAL) was obtained to perform cell count with differentials and E. coli culture, and to measure protein concentrations. The lungs were fixed in formalin for histological examination to compare the degree of inflammation. RESULTS: There were no significant differences in PaO2, cell count, differential count, E. coli culture between the study group and the control group. The protein concentrations of BALs in the surfactant-treated group were significantly lower than those in the control group (277+/-164 mg/dL vs 1,030+/-410 mg/dL). The inflammatory changes were found in E. coli-infected lung tissues from both groups, but less prominent in the surfactant-treated group than in control. CONCLUSION: Surfactant treatment decreased both the protein concentration of BALs and the inflammatory changes of lung tissue in an experimental model of E. coli pneumonia in rats.