Impacts Of Lung And Distal Organs Of Vaporized Perfluorocarbon Therapy On Seawater Respiratory Distress Syndrome Animal Models

[OBJECTIVE]To investigate the effect of vaporized perfluorocarbon therapy on seawater respiratory distress syndrome in animal models and to illustrate the mechanism of the therapy from multi-organ changes in organizational structure,expression of matrix metalloproteinase -9(MMP-9) in multiple organ.[METHODS]Forty Female Newsealand rabbits were randomly divided into five groups:â‘ CMV group:received conventional ventilation, Vt=8ml/kg,PEEP=0cmH₂O,PFC=0ml/kg.h;â‘¡PEEP group: received CMV and 8cmH₂O positive end expiratory pressure(PEEP) ventilation,Vt=8ml/kg,PEEP=8cmH₂O,PFC=0ml/kg.h;â‘¢PFC group:received CMV and 7ml/kg.h PFC vaporized inhalation, Vt=8ml/kg,PEEP=0cmH₂O,PFC=7ml/kg.h;â‘£PFC+ PEEP group: received CMV,PEEP and PFC vaporized inhalation,Vt=8ml/kg, PEEP=8cmH₂O,PFC=8ml/kg.h;⑤control group:without ventilation after making models.The animals in former four groups received different treatment for 2h followed by conventional ventilation 4h.Then animals were killed and lungs,small intestines,livers and kidneys in same area were cut into small slides. Morphometry were observed and evaluated after fixed in 10% buffered formalin.Molecular biology indexes were also calculated. Other 3 rabbits were directly killed to make light microscope studies. Part 1 To investigate the effects of vaporized perfluorocarbon on respiratory mechanics,hemodynamics mechanics and arterial blood gas indexes during and after different treatments.In addition,to observe the structural changes of lung,small intestine,liver and kidney after treatments.Part 2 We evaluated matrix metalloproteinase -9(MMP-9) to approach the mechanism of vaporized perfluorocarbon therapy. First,the level of the MMP-9 gene expression in the lung tissue was evaluated by the application of real-time fluorescence quantitative PCR.Second,the MMP-9 protein expression in extra-pulmonary organs(small intestine,liver,kidney) was observed by the application of immunohistochemistry.[RESUILS]1 Aggravation of respiratory mechanics and oxygenation indexes were observed after lung injury.Compared to CMV,these indexes statistically improved,after receiving vaporized PFC,PEEP and PFC+PEEP ventilation.In addition,PFC and PEEP had synergistic effect on oxygenation improvement during treatment. After treatment,the improvement of oxygenation in PFC group could even persist long time,but the oxygenation indexes in PFC+PEEP group decreased to equal with those in PFC group in one hour.All animals in C group died in fifteen minutes without ventilation.2 Compared to CMV group,significant decreasing pathological damage in lung tissue were observed in groups exposed toPEEP,PFC and PFC + PEEP.The pathological damages in liver tissue of PEEP group were also reduced significantly.No statistical difference was noticed in the rest groups.3 Expressions of MMP-9 in PFC,PEEP and PFC+PEEP groups were significantly lower than those in other two groups,especially in PFC+PEEP group.4 The expression of MMP-9 in kidney of experimental animals exposed to PFC and PFC+PEEP were significantly lower than those in CMV group by the method of immunohistochemistry.[CONCLUSION]1 Vaporized PFC,PEEP and vaporized PFC+PEEP ventilation could improve oxygenation indexes and lung compliant in SW-RDS animals,especially PFC+PEEP treatment.But after treatment,oxygenation indexes in group rapidly decreased and had no difference with those in PFC group in one hour.2 Vaporized PFC could inhibit the pathological damage of lung tissue,but not in extra-pulmonary organs,through down regulating expression of MMP-9.