Mild Hypothermia And Beating Heart Surgery To Reduce Postoperative Pulmonary Injury Mechanism And The High Mobility Group Protein B1 Expression

Backgroundpulmonary injury after cardiopulmonary bypass(CPB) was one of common complication after open heart operation. It could increase complication and mortality after operation. To explore lung protective measure in open heart operation was constantly hot spot in research area of Cardial Surgery. for the past few years research conclusions from clinic case summary and clinic study indicated operation on beating-heart with mild hypothermic cardiopulmonary bypass could lessen pulmonary injury after operation. But they did not represent mechanism of action. Accordingly mechanism of lessening pulmonary injury after operation on beating-heart with mild hypothermic cardiopulmonary bypass should be studied further.Pathophysiologic mechanism of pulmonary injury after open heart operation under CPB was not yet identified completely. Now systemic inflammatory response syndrome(SIRS) and pulmonary ischemia-reperfusion injury(IRI) were thought to be two major factors of pulmonary injury after CPB. But most scholars thought that SIRS was chief factor of pulmonary injury after CPB. Studies showed accumulation and activation of polymorphonuclear neutrophil(PMN) in lung was key link of pulmonary injury mechanism after CPB. Tumor necrosis factor(TNF-α) and interleukin-8(IL-8) play important role in pulmonary injury after CPB. They were important indexes of inflammatory reaction in lung. Nuclear factor-κB(NF-κB) could switch on and regulate gene transcription on inflammatory reaction, and mediated overexpression of inflammatory medium. NF-κB was important mechanism of pulmonary inflammatory reaction. HMGB1 played "advanced stage" inflammatory factor role outer cell. It was tested to be one of pathophysiologic mechanism of acute lung injury(ALI) originated from endotoxin, burns and hemorrhage and so on. It was few reported that HMGB1 participated pathologic processes of pulmonary injury after CPB or not.HMGB1 was a kind of protein which wide distributed in high eukaryotic organism. Under various kinds factor's stimulation, HMGB1 was released outer cell. HMGB1 was known as "advanced stage" inflammatory factor because it emerged late and exist long in inflammatory reaction. Now HMGB1's inflammatory action outer cell was paid high attention at home and abroad.It was tested to be one of pathophysiologic mechanism of Pyemia, Endotoxemia, IRI and ALI and so on.CPB could induce SIRS, and now it was thought to be Pathophysiologic mechanism of LCOS, ALI/ARDS, hemorrhage disease and brain disorder and so on after CPB. The pathophysiologic mechanism of SIRS was not completely identified during open heart operation under CPB. now it was thought that multiple mechanism had participated this pathophysiologic process. Be known as a "advanced stage" inflammatory factor, HMGB1's serum concentration would be increased or not, what was it's expressive law, and it would participate pathophysiologic process of SIRS after CPB or not, which was few reported.operation on beating-heart with mild hypothermic cardio-pulmonary bypass had refrained from myocardium's IRI and could decrease inflammatory factor's serum concentration, and it could decrease HMGB1's serum concentration or not? which was not reported.ObjetiveTo explore inflammatory mechanism of lightening pulmonary injury after operation on beating-heart with mild hypothermic cardiopulmonary bypass.To explore how HMGB1's serum concentration vary, what it is variety law, and what operation on beating-heart with mild hypothermic cardiopulmonary bypass influence on HMGB 1's serum concentration.Methods40 patients with rheumatic heart disease underwent mitral valve replacement were randomly divided into 2 groups. For patients in the experimental group, we underwent operation on beating-heart with mild hypothermic cardiopulmonary bypass, while Patients in the control group received operation on arrested heart with moderate hypothermia cardio-pulmonary bypass.1.To calculate respiratory Index(RI), monitor oxygenation index(OI) and static compliance of lung(Cs) before and after operation, and calculate ventilate time.2. Difference of transpulmonary PMN in blood was measured after opening chest and 30 min after CPB. By flow cytometry fluorescence male percentage of PMN's adhesion molecule CD11b/CD 18 was detected after opening chest and 30 min after CPB. Lung tissues was cut after opening chest and 30 min after CPB. By colorimetry the activity of myeloperoxidase(MPO) in lung tissue bomogenate was detected. By enzyme linked immunosorbent assay(ELISA) the levels of TNF-a and IL-8 of lung tissue bomogenate was measured. By western blotting the protein expression levels of NF-κB and HMGB1 was detected. By ELISA the serum level of NE was measured before, among and after CPB.3. By ELISA the serum levels of TNF-a, IL-8 and HMGB1were measured before CPB, at the end of CPB,6h after CPB,12h after CPB, 24h after CPB,48h after CPB.Result:1. respiratory function①The level of RI at the end of CPB, 1h after CPB and 8h after CPB was increased significantly compared with before operation in two groups(P<0.05,P<0.01). But the level in the control group was higher significantly than in the experimental group(P<0.05).②The level of OI at the end of CPB, 1h after CPB and 8h after CPB reduced significantly compared with before operation in two groups(P<0.05,P<0.01). But the level in the control group was lower significantly than in the experimental group (P<0.05).③The level of Cs at the end of CPB, 1h after CPB and 8h after CPB was decreased significantly compared with before operation in the control group(P<0.01) and the level at the end of CPB,1h after CPB was decreased significantly in the experimental group(P<0.01). But the level in the control group was lower significantly than in the experimental group (P<0.05).④The duration of ventilation was not statistically significant between two groups(P>0.05).2.The accumulation and activation of PMN in lung①The difference of transpulmonary PMN, male percentage of CD11b/CD 18 in blood and activity of MPO in lung tissue bomogenate at 30min after CPB was increased significantly compared with after opening chest in two groups(P<0.01).But The levels at 30min after CPB in the control group were higher than in the experimental group(P<0.05).②The serum level of NE at 30 min after CPB, the end of CPB,3h after CPB,6h after CPB and 12h after CPB was increased significantly compared with before CPB in the control group(P<0.05, P<0.01), and the level in the experimental group was increased significantly except12h after CPB(P<0.05, P<0.01). But the level at 30 min after CPB, the end of CPB,3h after CPB and 6h after CPB in the control group was higher than in the experimental group(P<0.05).3.The levels of TNF-a and IL-8 in lungThe levels of TNF-a and IL-8 in lung tissue bomogenate at 30min after CPB was increased significantly compared with after opening in two groups(P<0.01, P<0.05). But The levels in the control group were higher than in the experimental group(P<0.05).4. The protein expression levels of NF-κB and HMGB1①The protein expression level of NF-κB in lung tissue at 30min after CPB was increased significantly compared with after opening in two groups(P<0.01). But The level in the control group was higher than in the experimental group(P<0.05).②The protein expression level of HMGB1 in lung tissue 30 min after CPB was not higher than after opening chest in two groups(P>0.05). The level was not statistically significant between two groups(P>0.05).5. The serum levels of TNF-a, IL-8 and HMGB1①The serum level of TNF-a at the end of CPB,6h after CPB,12h after CPB and 24h after CPB was increased significantly compared with before CPB in two groups(P<0.01),and the level in the control group was higher than in the experimental group(P<0.05).②The serum level of IL-8 at the end of CPB,6h after CPB,12h after CPB,24h after CPB and 48h after CPB was increased significantly compared with before CPB in two groups(P<0.01,P<0.05), and the level in the control group was higher than in the experimental group(P<0.01).③The serum level of HMGB1 at 6h after CPB,12h after CPB,24h after CPB and 48h after CPB increased significantly compared with before CPB in two groups(P<0.01), and the level in the control group was higher than in the experimental group(P<0.01, P<0.05).④The serum level variation trend of TNF-a, IL-8 and HMGB1 The serum levels of TNF-a and IL-8 was increased significantly at the end of CPB, moreover reached peak at the end of CPB and 24h after CPB, while those recovered normal at 48h after CPB. The serum level of HMGB1 began to step-up at 6h after CPB, moreover reached peak at 24h after CPB, was increased still significantly at 48h after CPB.Conclusion1. Operation on beating-heart with mild hypothermic cardio-pulmonary bypass could lessen pulmonary injury after CPB, however it also posed pulmonary injury to extent. How to consummate lung protection of operation on beating-heart with mild hypothermic cardiopulmonary bypass should study further.2. The mechanism of lessening pulmonary injury on operation on beating-heart with mild hypothermic cardiopulmonary bypass, was related to it's reducing accumulation PMN in lung, decreasing expression of CD11b/CD18 and release of NE, lessening lung's inflammatory reaction, inhibition of activity of NF-κB and so on.3. During open heart operation under CPB, HMGB1,known as a "advanced stage" inflammatory factor, participated pathophysiologic process of SIRS after CPB. operation on beating-heart with mild hypoth-ermic cardiopulmonary bypass could decrease release of HMGB1 and lessen SIRS after CPB.