| Objective Traditional OLV collapsed the surgery side of lung completely through the double-lumen tube or bronchial bloker.Though it can well expose the operative field and provide a good operating environment,this non-physiological ventilation can cause severe pulmonary ventilation/blood flow unbalanced,increase pulmonary shunt,lead to hypoxemia;ischemia and hypoxia and lung reexpansion reoxygenation process produced a large number of oxygen free radicals caused oxidative stress,causing lung inflammation,eventually led to acute lung injury.Numbers of studies have shown that lung protective ventilation strategy and selective lobar blockade can be used to reduce acute lung injury caused by one-lung ventilation.However,few studies have suggested that lung injury can be reduced by controlling the degree of collapse of the operated lung.Our research group has developed a new type of single-lumen lung isolation tool——Intra-pulmonary Balance Gas-separation Lungs Isolation Catheter(Patent No.:ZL201520247672.2,International Application No.:PCT/CN2017/083268),it has been confirmed that the catheter can control the degree of collapse of the surgical lung without affecting the operative field,to retain part of the alveolar ventilation and improve the ventilation/blood flow ratio in the collapsed lung and reduce the lung inflammatory response.In this study,the material structure of the catheter was studied,and we continued to use it for animal experiments to observe the advantages of the new pulmonary isolation catheter in the lung isolation technology and the effects of complete collapse and controlled(partial)collapse on the lung tissue immune inflammatory response and oxidative stress during OLV,and investigate the protective effect of controlled lung collapse on the collapsed lung.Method(1)The catheter’s material structure was studied through material selection,structure design,and structural strength studies,left and right lung balanced gas diversion was studied through Aerodynamic Balanced Gas Distribution of Stokes Einstein Relation and Bernoulli Equation,desighed to optimize the catheter’s structure,form samples of intra-pulmonary balanced gas-seperation lung isolation catheter.(2)Aimal experiment of lung protection on intra-pulmonary balanced gas-seperation lung isolation catheter:18 experimental dogs(provide by Southern Medical University Animal Experimental Center),both male and female,weighing 12.5±3 kg.Devided into 3 groups by random number table:complete lung collapsed group(group A,right lung 100%collapsed),90%lung collapsed group(group B,leaving the right lung 10%ventilation),50%lung collapsed group(group C,leaving the right lung 50%ventilation),6 dogs in each group.Dogs were fasted for 12 hours before operation.Peripheral venous access was established through small saphenous vein,injected of 3%sodium pentobarbital(30 mg/kg),fentanyl(2 μg/kg),cisatracurium besylate(0.lmg/kg)for general aneasthesia.The animals were placed in the supine position and the limbs fixed after the insertion of intra-pulmonary balanced gas-seperation lung isolation catheter,anesthesia machine for mechanical ventilation,with 1-2%sevoflurane,intermittent additional cisatracurium besylate to maintain anesthesia during the experiment,the ventilator parameters were set as follows:100%oxygen concentration(FiO2),10-15 ml/kg tidal volume(VT)and 12-16 breaths/min respiratory rate(RR).During the course of the experiment,continuous monitoring of PEtCO2,limb electrocardiogram,rectal temperature,and blood oxygen saturation of the tongue detection probe was used to monitor the oxygen saturation.Freed right femoral artery and punctureed catheter were used to monitor the arterial blood pressure(ABP)of the femoral artery and arterial blood samples.Freed right internal jugular vein,punctureed and inserted the floating catheter of Swan-Ganz and embedded in the pulmonary artery for monitoring mean pulmonary arterial pressure(MPAP)and collection of mixed venous blood samples.The small saphenous vein was inputed compound sodium chloride injection(8 ml/kg/h)to supplement the liquid to maintain capacity balance.Maintained the operating room temperature at 24-26℃ and humidity at 67%-73%.The experimental animals were all subjected to two-lung ventilation(TLV)for 20 min.The right lung was collapsed by controlling the size of the inner microcapsule at the lower end of the controlled lungs balance air separation pulmonary isolation catheter,the degree of collapse was controlled as described in the previous subgroup.In each group,vital signs and blood samples were collected at 1 min before right lung collapsed(T1),30 minutes(T2),60 minutes(T3)and 120 minutes(T4)after lung collapsed.After centrifugation at 4℃,3000 rpm and 12 min,the supernatant was taken and stored in a-80℃ freezer for mesuring the content of intercellular adhesion molecule 1(ICAM-1)and malondialdehyde(MDA),and the activity of superoxide dismutase(SOD).The measurement data were expressed as mean ± standard deviation(x±s),statistical analysis was performed by SPSS 20.0 software.The variance analysis of repeated measurement data was used in the group and the group t test was used for comparison among groups.P<0.05 was considered statistically significant.Results(1)Generated of side hole distribution technology,hole drilling technology and microcapsule sealing technology for intra-pulmonary balanced gas-seperation lung isolation catheter.(2)Compared with the previous experimental results,there was no significant difference in mean arterial blood pressure(MAP)and HR at each time(P>0.05);mean pulmonary artery pressure(MPAP)in groups B and C was significantly lower than that in T2,T3 and T4 were lower than those in group A at each time point(P<0.05),but there was no significant difference between time points(P>0.05).There was no significant difference between group B and group C.(3)Comparison of oxygenation index:Compared with T1,PaO2 and PvO2 of three groups were significantly lower at T2,T3 and T4,Qs/Qt was significantly increased(P<0.05),PaCO2 was not significantly changed(P>0.05).PaO2 and PvO2 in each group showed a decreasing trend at 4 time points(P<0.05),while Qs/Qt increased at 4 time points(P<0.05).Compared with group A,PaO2 and PvO2 in groups B and C increased significantly at T2,T3 and T4,and Qs/Qt significantly decreased(P<0.05).Compared with group B,PaO2 and PvO2 in group C were significantly higher at T2,T3 and T4(P<0.05),Qs/Qt significantly decreased at T2,T3(P<0.05).PaCO2 in group A showed no significant difference with groups B and C at all time points(P>0.05).(4)Changes of serum ICAM-1,MDA content and SOD activity:compared with T1,the levels of ICAM-1 in three groups were significantly increased at T2,T3 and T4(P<0.05),and increased with the increase of time.Compared with group A,the content of ICAM-1 in groups B and group C was significantly lower than group A at T2,T3 and T4(P<0.05).The change of MDA was similar to that of ICAM-1.Compared with T1,the content of MDA in the three groups was significantly increased(P<0.05)and increased with the increase of time.Compared with T1,the content of MDA in groups B and C was significantly lower than that of group A(P<0.05),and the content of MDA in group C was lower than that of group B(P<0.05).Compared with T1,the activity of SOD in the three groups decreased significantly at T2,T3 and T4(P<0.05),and decreased with the increase of time.Compared with T1,the activities of SOD in groups B and C at T2,T3 and T4 The activity of SOD in group C was higher than that in group A(P<0.05).The activity of SOD in group C was higher than that in group B(P<0.05).Conclusion(1)Intra-pulmonary balanced gas-seperation lung isolation catheter has certain advantages in the technique of lung isolation,it can control the size of the inner capsule to control the ratio of the air flow through the catheter,and then implement controlled lung collapse without affecting the operative field of vision.(2)The results of this experiment demonstrate once again that ventilaton of partial alveolar remained in the collapsed lung can significantly improve the ratio of alveolar ventilation/blood flow,reduce the rate of intrapulmonary shunt,and increase oxygenation.(3)Retaining a certain degree of ventilation on the collapsed side of the lung can reduce the content of ICAM-1 and MDA in the lung tissue,increase the activity of SOD,and help to reduce the oxidative stress and immune inflammatory response in the lung tissue.(4)Compared with complete lung collapse(100%collapse),controlled lung collapse(90%collapse and 50%collapse)is more conducive to the reduction of lung injury of OLV and has a protective effect on the lungs.The collapse of 50%more significant than collapse of 90%,suggesting that collapse of 50%may have more significant lung protection. |
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