Established A ARDS Of Sheep Model With Heat Smoke Injury Combined With Mechanical Ventilation And Observed The Effect Of Low Tidal Volume Ventilation Combined With ECMO In Treatment Of Sheep

ObjectiveTo explore the animal model of ARDS established by smoke inhalationlung injury combined with invasive mechanical ventilation,and observe the effect of early low tidal volume ventilation combined with ECMO on sheep ARDSmodel.MethodsThe first part is the modeling experiment: We selected 24 healthy female little Tailed Han sheep and randomly divided them into four groups: sham operation group(group SO,n=6),mechanical ventilation group(MV group,n=6),smoke exposure group(S group,n=6),model group(M group,n=6).Group SO as a control group,Group MV was given mechanical ventilation for 30 min after anesthetized(MV Mechanical Ventilation).Group S was given smoke exposure after anesthesia,and M group was given MV for 30 min after exposure tosmoke as well.Computed Tomography(CT)was Separatly performed 12 h before and after injury and 72 h after injury.Arterial blood sampling were performed for each2/4/6h,and fast learning analysis and detection(specific time and duration of injury and physiological status of animals).Observed animal 72 h after injury or to animal death.Carring out an autopsy and collecting pathological specimensat the time of death.The second part is the treatment experiment: select 18 healthy female non pregnant Small Tail Han sheep.They were randomly divided into three groups: control group(group C,n=6),low tidal volume ventilation group(L group,n=6),treatment group(E group,n=6).The basic operation of the same as the first part(including: skin preparation,anesthesia,tracheotomy,etc.)to determine the successful establishment of ARDS model,the control group was given the same treatment.Low tidal volume group was given low tidal volume protective ventilation.The treatment group was given low tidal volume protective ventilation and Established VV-ECMO at the same time.ResultsThe first part of the modeling experiment results: Comparison of oxygenation index results within 12 h after injury,There was significant difference oxygenation index beteeen M group and S group(P < 0.05),while SO group and MV group without significant differences(P > 0.05).After 12 h to 72 h,there was significant difference in oxygenation index between group S and MV group(P < 0.05),but group MV and SO group without significant differences(P > 0.05).The results of autopsy showed that there was no obvious damage to lungtissue in group SO and group MV,but there was a certain degree of damage to lung tissue in group S,and group M was similar to diffuse alveolar injury(DAD ARDS pathological mark).Imaging examination: At 24 h and 72 h time point,SO group and MV group showed no obvious change of chest CT;The CT of animal in S group can be seen scattered and density increased;In group M,most of pulmonary tissues with glass-like increased density and thickening of lung texture were found.The second part of the experiment showed that the oxygenation index of group L and E had improved after the lesion in 12 to 36 hours.But there is no change in imaging.The group C showed a pathological features of severe inflammatory infiltration and alveolar edema and destruction.The pathological results of group E were similar to group L.ConclusionsSimple smoke injury can cause a certain degree of lung injury,but it can not reach the standard of ARDS.A mechanical ventilation pattern that does not cause damage to normal animals,however,it will aggravate the injury caused by smog injury and induce ARDS in laboratory animals.Low tidal volume mechanical ventilation can maintain the oxygenation level of ARDS sheep model to a certain extent.ECMO can improve the oxygenation level of the ARDS sheep model,but there is no credible evidence for the treatment of lung injury.