The Protective Effect Of L-Arg And Salvia Perfusion To Pulmonary Artery On Immature Canine's Lung During Cardiopulmonary Bypass

The incidence of lung complication is always high after cardiopulmonary bypass in infants such as lung edma, atelactatic or respiratory distress syndrome. It relates to operation failure or mortality of the patients undergoing CPB. However, the study of immature lung protection is deficient nowadays. In this study, we established a CPB model of immature animal to study the possible mechanism of immature lung injury and to assess the protection of perfusing hypothermia protect solution and additive through pulmonary artery. The study includes three parts:Experimental MethodologyIn this experiment, 56 healthy infant canine (male or female, aged 28 ~ 32 days) were used, each weighing 1.0~2.0kg. Giving no food for 6 hours before the study, they were divided into seven groups: sham operation group, CPB group, Control group, CPB group, LPD perfusion group, L-Arg perfusion group and Salvia group (n=8).In sham operation group, sternotomy heparin was injected and maintained for 120 minutes. In CPB group, CPB was set up through right arteriae carotis communis and right atrium after connecting tubes and priming. When the temperature was 30°C, aorta and pulmonary artery were crossclamped. The heart was arrested with cold modified St.Thomas II solution(4°C ).After 60min, aorta and pulmonary blood flow were reestablished. Part CPB continued for 60min,pieces of lung tissue were collected and observed with light microscope and transmit electron microscope (TEM). In the LPD perfusion group, LPD lung protect additive was constantly perfused at the right lungartery, with its flow 150ml/Kg/h and the pressure 14~16mmHg. In the L-Arg perfusion group and Salvia perfusion group, the pulmonary artery perfusion was conducted after adding L-Arg and salvia to the LPD respectively. The sample of lung tissue was made after the power-off in each group. The PaO2/FiO2 of lung venous blood, the content of PS in BALF, content of NO, MDA and the activity of MPO were measured. The Wet/Dry ratio and vascular permeability (EB) were calculated.Result:1. In CPB group, PaO2/TiO2 and the content of PS, NO were significantly lower than that of sham operation group(p< 0.01). The content of MDA and the activity of MPO in CPB group were significantly higher than that of sham operation group(p< 0.01). The W/D and EB were also higher than that of sham operation group(p< 0.01). In CPB group, the pulmonary interstitial edma and leukocyte infiltration were severe. Alveolar wall was destroyed and exudation and bleed existed in alveolar cavity.2.1n the LPD perfusion group, the level of PaO2/FiO2,PS,NO was significantly higher than that of CPB group while the level of W/D and EB was lower(p< 0.01). The changes of content of MDA and activity of MPO were the same(p< 0.01). The histological and ultrastructure changes of the LPD group were less severe than that of in CPB group.3. hi the L-Arg perfusion group and Salvia perfusion group, the level of PaO2/FiO2, PS, NO was significantly higher than that of LPD group while the level of W/D and EB was lower(p< 0.05 or 0.01). The changes of content of MDA and activity of MPO were the same(p< 0.05 or 0.01). The histological and ultrastructure changes of the L-Arg group and Salvia group were less severe than that of LPD group, with the CPB group the least.Conclusion:l.The infant canine CPB model is an ideal immature animal CPB model.2.The "hot" ischemia-reperfusion of lung during CPB, the activated and adhesion to vascular endothelium and infiltration of neutrophil play an important role in the lung injury and pulmonary dysfunction after the operation undergoing CPB.