Outcome And Mechanism Of Sevoflurane On Acute Lung Injury Induced By Cardiopulmonary Bypass In Patients Undergoing Heart Surgery

Part 1 Protective effects of sevoflurane on acute lung injury induced by cardiopulmonary bypass in patients undergoing heart valve replacement surgeryBackground:Subclinical acute lung injury（ALI）can often occur after cardiac surgery under cardiopulmonary bypass（CPB）.The main clinical manifestations are hypoxemia caused by pulmonary edema,and severe cases can lead to acute respiratory distress syndrome（ARDS）.However,its mechanism of action needs further study.Volatile anesthetics such as sevoflurane can exert certain organ protection effects on major organs such as heart and lung through their pretreatment and post-treatment effects.Although the mechanism of organ protection provided by volatile anesthetics is currently unclear,recent studies have shown that isoflurane and halothane have anti-inflammatory effects and can reduce lung damage caused by lipopolysaccharide and mechanical ventilation stimulation.A large number of secreted pro-inflammatory cytokines.In this study,we selected patients undergoing cardiac valve replacement under CPB and intervened with sevoflurane to investigate the effect of perioperative lung injury on patients with such surgery.Objective:This study intends to preliminarily discuss the protective effect of sevoflurane on lung injury in patients undergoing heart valve replacement surgery with cardiopulmonary bypass.Methods:Sixty patients who underwent elective cardiac surgery in the Department of Cardiac Surgery,Second Affiliated Hospital of Zhengzhou University from January2016 to December 2017 were enrolled.The patients underwent cardiopulmonary bypass under general anesthesia.Patients enrolled in the study were divided into two groups（n=30）according to the random number table:control group and sevoflurane group.All patients undergoing surgery are performed by the same team of surgeons.Patients included in the study included criteria:no gender restrictions,age 40 to 65years,weight 50.0 to 80.0 kg,height 150.0 to 180.0 cm,American Society of Anesthesiologists（ASA）classification II to III,New York Heart Association（NYHA）Cardiac function grade II/III,left ventricular ejection fraction（EF%）>50%.All patients were divided into two groups according to the random number table:propofol group（P group）and sevoflurane group（Sev）,30 cases in each group.Patients in the Sev group received inhaled sevoflurane combined with remifentanil,sevoflurane maintained a minimum endogenous alveolar concentration（MAC）of 1.2,and group P received propofol intravenously with remifentanil.Record general clinical data of preoperative patients.The input volume of blood products such as chest drainage,red blood cell suspension,fresh frozen plasma,cryoprecipitate and platelets within 24 hours after surgery was recorded.Before induction of anesthesia（T0）,10 min after induction（T1）,rewarming to 36°C（T2）,CPB discontinuation 1 h（T3）,surgery（T4）,and 24 h after surgery（T5）The levels of serum tumor necrosis factor-α（TNF-α）,interleukin-6 and 8（IL-6,IL-8）were measured by enzyme-linked immunosorbent assay（ELISA）in patients with internal jugular vein blood.The usage of vasoactive drugs,CPB time,ascending aorta block time,chest closing time,deep hypothermic circulatory time and operation time were recorded in the two groups.The postoperative chest opening hemostasis rate and postoperative complications were recorded in the two groups.Results:1.There was no significant difference in the left ventricular ejection fraction（EF value）and the number of flaps between the two groups（P>0.05）.2.Compared with group C,MAP and CVP of Sev group were significantly increased at T1^T6（P<0.05）,while the HR at T1^T3 was significantly decreased（P<0.05）.3.Compared with before CPB,PaO₂ was significantly lower（P<0.05）in the two groups of patients at the time of 2 h after CPB;compared with group C at the same moment,PaO₂ was increased significantly（P<0.05）in Sev group of patients at the time of 2 h after CPB;PaCO₂ had no statistical significance（P>0.05）in two groups of patients at different time points.4.Compared with T0 in the same group,the levels of TNF-αand IL-6 and Il-8in the two groups were all increased at T2^T5（P<0.05）.Compared with group C,the levels of serum TNF-αand Il-6 and Il-8 in Sev group were all decreased at T2^T5（P<0.05）.5.There were no statistically significant differences in the incidence and mortality of the two groups of patients after 24 h after surgery,such as anaphylaxis,renal insufficiency and hepatic insufficiency（P>0.05）.6.There was no statistically significant difference in the incidence of postoperative complications between the two groups（P>0.05）after postoperative mechanical ventilation time,ICU retention time,sinus bradycardia hypotension,and re-intubation in the endotracheal tube.7.There was no statistically significant difference in duration of CPB,aortic occlusion time and time of deep hypothermia and operation time between the two groups.8.Compared with group C,there was no statistically significant difference in the amount of plasma erythrocyte platelet and cold precipitation after 24 h thoracic duct drainage in Sev group（P>0.05）.9.There was no significant difference in the incidence and mortality of secondary hemostatic hemostasis and postoperative complications such as ALI,AKI,CRRT,transient neurological dysfunction,and permanent neurological dysfunction in the two groups（P>0.05）.Conclusion:Sevoflurane can reduce the inflammatory response in lung tissues,and it has better protective effect on patients with heart valve replacement surgery caused by CPB,and its mechanism needs further discussion.Part 2 Effects of Sev preconditioning on oxidative stress,inflammatory response and pulmonary UPR in rats with acute lung injury induced by cardiopulmonary bypassBackground: At present,a large number of studies have confirmed that apoptosis plays a key role in the development of acute lung injury（ALI）,and this may be one of the main causes of ALI after cardiac valve replacement surgery under CPB.However,how CPB causes apoptosis in lung tissue cells is still unclear.At present,the mechanism of CPB-induced lung injury is not clear,and its prevention and treatment measures have always been one of the focuses of many scholars.Studies have confirmed that unfolded protein response（UPR）plays an important role in ALI caused by CPB.At the same time,active intervention in UPR can alleviate ALI.Sevoflurane（Sev）is a commonly used inhalation anesthetic in clinical practice,and its clinical effect is better.At the same time,basic research has confirmed that the inhaled anesthetic can have a better protective effect on the lungs of rats with ischemia/reperfusion.However,how Sev can alleviate the ALI caused by CPB has many controversies.And the arguments are different.Therefore,this experiment replicates the ALI model induced by CPB in rats,and starts from the oxidative stress,inflammatory response and UPR in lung tissue to explore the mechanism of action of Sev,and provide more basis for clinical practice.Objective: This study was to investigate the effects of pre-administration of Sev on oxidative stress,inflammatory response and UPR in lung tissue induced by CPB in rats,and to explain more possible mechanisms of Sev,and provide theoretical basis for clinical practice.Methods: A total of 45 adult healthy Sprague-Dawley（SD）rats were randomly divided into 3 groups according to the random number table（n=15）: Sham group rats were only subjected to arterial and venous puncture;CPB group rats were established CPB.After the flow was gradually adjusted to the maximum（100 ml·kg-1·min-1）to maintain flow for 60 min;Sev was pre-administered to the +CPB group（Sev group）.Rats were inhaled 2.5% sevoflurane for 30 minutes,after 15 min Prepare the CPB model.Arterial blood samples were collected before CPB and 2 h after CPB（before arterial and venipuncture and 3 h after puncture in Sham group）and blood gas analysis was performed to determine the partial pressure of oxygen（Pa O2）and partial pressure of carbon dioxide（Pa CO2）.Venous blood was collected before CPB and 2 h after CPB（before arterial and venipuncture and 3 h after puncture in Sham group）and serum superoxide dismutase（SOD）was measured by xanthine oxidase method.Vitality,rat serum methane dicarboxylic aldehyde（MDA）was measured by thiobarbituric acid method,and myeloperoxidase（MPO）was determined by enzyme linked immunosorbent assay（ELISA）.The serum levels of tumor necrosis factor-α （TNF-α）,interleukin-6（IL-6）and IL-8 were determined by ELISA.At the end of the experiment,the left lung of the rat was taken and the wet weight to dry weight（W/D）and total lung water content（TLW）were measured.Light microscopy was used to detect lung histopathological changes and index of quantitative evaluation for alveolar damage（IQA）.Electron microscopy was used to detect ultrastructural changes in lung tissue.Td T-mediated d UTP nick end labeling（TUNEL）was used to determine the apoptosis of lung tissues and calculate the apoptotic index（AI）.Reverse transcription-polymerase chain reaction（RT-PCR）was used to determine glucose-regulated protein 78（GRP78）and CCAAT enhancer-binding protein（C/EBP）homologues in lung tissue.CCAAT enhancer binding protein（C/EBP）homologous proteins（CHOP）,c-Jun N-terminal protein kinase（JNK）and cysteinyl aspartate specific proteinase 12,caspase-12)m RNA expression level.Western blot was used to detect the expression of GRP78,CHOP,phosphorylated JNK（p-JNK）and caspase-12 in lung tissue.Results:1.At 2 h after CPB,Pa O2 in CPB group was significantly lower than that in Sham group（P<0.05）.Pa O2 in Sev group was significantly higher than that in CPB group.There was statistical difference between th two groups（P<0.05）.2.At 2 h after CPB,the content of serum MPO and the level of MDA in CPB group were significantly higher than those in Sham group,while the activity of SOD was significantly decreased,and the difference between the two groups was statistically significant（P<0.05）.The content of serum MPO and the level of MDA were significantly lower than those in CPB group,while the activity of SOD was significantly increased,and the differences between the groups were statistically significant（P<0.05）.3.At 2 h after CPB,the levels of serum IL-8,TNF-α and IL-6 in CPB group were significantly higher than those in Sham group（P<0.05）,while in Sev group,the levels of serum IL-8,TNF-α and IL-6 were significantly lower than CPB group at 2 h after CPB,and the differences between the two groups were statistically significant（P<0.05）.4.IQA,W/D,AI and TLW of lung tissue in CPB group were significantly higher than those in Sham group,and the differences between the groups were statistically significant（P<0.05）.IQA,W/D,AI and TLW of lung tissue in Sev group were significantly lower than those in CPB group,and there was significant difference between groups（P<0.05）.5.The results of light microscopy showed that the lung tissue structure of Sham group was clearly visible,the structure of alveolus was intact,the septum was normal,there was no edema of lung interstitium,there was no congestion in the alveoli or the exudation of inflammatory cells;while in the CPB group,the lung tissue The structure was damaged,the alveolar part did not expand,red blood cells leaked out in the alveolar cavity and interstitial lung,edema of the pulmonary interstitium was thickened,and a large number of inflammatory cells infiltrated;Sev group reduced lung tissue damage,alveolar structure was relatively intact,and alveolar cavity Erythrocytes leaked less,and lung interstitial inflammatory cell infiltration was not obvious.6.The results of electron microscopy showed that the ultrastructure of lung tissue in the Sham group was not significantly altered.In alveolar type II epithelial cells in the CPB group,cell swelling was evident,surface microvilli were significantly reduced or even disappeared,mitochondria and other organelles were significantly swollen,lamellae gradually appeared vacuoles or decreased or even disappeared,and nuclei fragmented more.Chromatin is clearly unevenly distributed.In the Sev group,the damage of ultrastructure of the lung tissue was significantly reduced,the shape of the alveolar type II epithelial cells was clearer,the swelling of the cells was reduced,the surface microvilli increased,the mitochondria and other organelles tended to be normal,the lamellar bodies increased,and the nucleus boundary was more complete.The chromatin is relatively uniform.7.TUNEL assay results showed that most of the lung tissues in Sham rats were normal cells.The CPB group had obvious apoptosis in the lung tissue and a large number of apoptotic cells,while the Sev group had less apoptosis in the lung tissue cells,and the number of apoptotic cells was significantly less.8.The expression of CHOP,GRP78,caspase-12 and JNK m RNA and protein in lung tissue of CPB group was significantly higher than that of Sham group,and there was significant difference between groups（P<0.05）.The expression of CHOP,GRP78,caspase-12,and JNK m RNA and protein in lung tissue of Sev group was significantly lower than that of CPB group,and there was significant difference between groups（P<0.05）.Conclusion:1.The possible mechanism of ALI induced by CPB in rats is related to inflammatory reaction,oxidative stress and UPR-related apoptosis in lung tissue.2.Pre-administration of sevoflurane can alleviate ALI caused by CPB in rats by alleviating inflammatory and oxidative stress in lung tissue and inhibiting UPR-related apoptosis.