The study of hyperoxic liquid therapy for acute respiratory distress syndrome induced by oleic acid

Objective To study the therapeutic effect and mechanism of hyperoxic liquid(HO)therapy for rats with acute respiratory distress syndrome(ARDS)induced by oleic acid.Methods Ringer solution was used as the base solution to prepare HO solution,and 30 rats were randomly divided into 3 groups(10 in each group):oleic acid group(group A),oleic acid + HO therapy group(group B)and normal control group(group C).Group A and group B were injected oleic acid(0.1 ml/kg)via the right femoral vein to set up ARDS models,while group C was injected Ringer's solution in the same way.Thirty minutes later,group B was infused HO(10 ml-1 ·kg-1·h-1)via the right femoral vein,while group A and group C were infused with Ringer's solution in the same way.Each group was taken blood via the right common carotid artery at 0 min(before injected oleic acid),30 min,60 min and 120 min(after injected oleic acid)to detect PaO2,SaO2,PaCO2,pH,BE,and HCO3-,respectively.Two hours later,the rats were killed and the lungs were taken out.The concentration of malonaldehyde(MDA)and the activity of superoxide dismutase(SOD)in the lungs were detected.The water content in the lungs and lung/body mass ratio were calculated.The pathological changes of lungs were observed.Results Compared group A with group B,the former had a significant decline of PaO2(P0.01),a great rise of lung water content and lung/body mass ratio(P0.01),an increased MDA concentration and a decreased SOD activity(P0.05);the lung had focus hemorrhage,mesenchymal and alveolus edema,and a great deal of inflammatory cells infiltration when observed by microscopy.Compared group A with group B,the latter had a rapid rise of PaO2(P0.05),less severe pneumonedema,lower MDA concentration(P0.05)and higher SOD activity(P0.05)after treatment with HO;the injury had a obvious alleviation in the bulk of lung tissue when observed by microscopy.Conclusions The mechanism of ARDS induced by oleic acid may be caused by oxidative injury.HO could therapy rats with ARDS induced by oleic acid,and better effect could be obtained if using it earlier.