To Explore The Safe Time Limit Of Extrac Orporeal Circulation In Peripheral Femoral Artery And Vein During Total Thoracoscopic Heart Surgery

Background:In some emergencies,such as ascending aortic aneurysms,aortic dissection aneury-sms and ascending aortic replacement surgery,as well as other emergencies,femoral artery and venous intubation is often the preferred location.In addition,with the development of minimally invasive techniques in cardiac surgery,the use of peripheral extracorporeal circulation has become more and more common,and the peripheral extracorporeal circulation technology has become more and more mature,among which femoral artery and venous cannula are the most common.With the increasing application of femoral artery intubation,the incidence of complications caused by reperfusion injury is very high.It has been reported that about 13%of patients with femoral artery intubation suffer from lower limb ischemia reperfusion injury,which may have more serious consequences,which deserves our attention.In recent years,ischemia reperfusion injury（I/R）has been particularly prominent in surgery,especially in cardiac surgery.Ischemia reperfusion injury refers to the injury caused by reperfusion of blood flow in the case of tissue or organ ischemia,which is even more serious than before,and some are irreversible.Ischemia reperfusion（I/R）can occur in most human organs,especially the heart and kidneys.Whether reperfusion injury is safe for patients has been shown by numerous studies to depend on ischemia time,ischemia degree and reperfusion conditions.Cardiac surgery is characterized by cardiac arrest,cardiopulmonary bypass and myocardial protection.With the development of these technologies,peripheral cardiopulm-onary bypass and cardiac protection of cardiac arrest are gradually mature.The chest space in which the heart is located has the basic conditions for exposing the field of vision under the endoscope and performing thoracoscopic cardiac surgery.Therefore,it is feasible to perform total thoracoscopic cardiac surgery without thoracotomy,but the safe time limit for cardiac arrest makes it more challenging.Total thoracoscope technology have the advantages of small incision,the advantages of rapid recovery,with the progress of the thoracoscope heart surgery technology and ischemia-reperfusion injury research deepening,our total thoracoscope surgery due to shares,venous cannula in tissue hypoperfusion and ischemia-reperfusion injury is becoming more and more important,but now about the thoracoscope heart surgery peripheral strands of arteries and veins extracorporeal circulation security time limit of exploring experiment research is less.The purpose of this study is to explore the safety time limit of establishing extracorporeal circulation of peripheral femoral artery and vein in total thoracoscopic cardiac surgery,which can be used for reference in guiding the safety time of cardiac surgery.Purpose:The results of blood gas analysis at different times were measured during perioper-ative period of extracorporeal circulation of femoral artery and vein intubation,to explore the safe time limit of establishing extracorporeal circulation of femoral artery and vein during open heart surgery under total thoracoscopy.Methods:From October 2016 to November 2018,40 patients underwent total thoracoscopic cardiac surgery in the department of cardiac surgery of liaocheng people’s hospital,including 25 patients with atrial septal defect（ASD）.VSD was found in 15 cases.There were 18 male cases and 22 female cases.Age 3～12 years old,height 95～142cm,weight15.6～46.0kg,excluding patients transferred to thoracotomy.All the patients underwent cardiopulmonary bypass by right femoral artery and femoral vein intubation,and then underwent cardiac surgery after ascending aorta occlusion and aortic root perfusion with cardiac arrest fluid.Blood gas of arteries and veins was extracted at three time points before intubation,immediately after the resumption of blood supply of lower limbs at the intubation side and 1h after the resumption of blood supply,and the changes of oxygen partial pressure（PO₂）,PH value,lactic acid（Lac）and carbon dioxide partial pressure（PCO₂）were monitored.According to the length of extracorporeal cycle time(T_CPB),the patients were divided into three groups:group A(T_CPB≤2h,n=15),group B(2h<T_CPB≤3h,n=14)and group C(T_CPB>,3h,n=11).The changes of indicators at each time point were compared between each group,and the influences of the duration of extracorporeal cycle on the body were analyzed.T test was used for comparison between groups,and data were expressed as mean±standard deviation（X±S）.Results:All the 40 patients survived the operation successfully.One case of lower extremity swelling on the side of intubation occurred in group B and group C,and recovered after treatment without serious complications such as limb necrosis on the side of intubation.There was no significant difference in gender,age,weight and height between groups A,B and C（p>0.05）.In group A,CPB=105.9±12.75 min,in group B,T_CPB=148.3±14.26 min,and in group C,T_CPB=207.9±21.42 min.Blood gas results before intubation showed no significant differences in PH,PO₂,PCO₂ and Lac.Analysis of blood gas results immediately after the recovery of blood supply to the lower extremities of the patients showed that there was no significant difference between arterial partial blood pressure（PO₂）and partial blood pressure（PCO₂）groups,and both were within the normal range.There was no statistically significant difference in arterial PH value between group A and group B（P>0.05）,while there was significant difference between group C and group A（P<0.05）.There were significant differences in venous PH value,oxygen partial pressure（PO₂）and carbon dioxide partial pressure（PCO₂）（P<0.05）.Lac values were different among the three groups（P<0.05）.1h after the resumption of blood supply at the intubation side,the results showed that only group C and group A had different Lac values（P<0.05）.There was no significant difference in the remaining indicators（P>0.05）.Conclusions:When total thoracoscopic cardiac surgery establishes peripheral extracorporeal circulation through femoral artery and vein,with the extension of extracorporeal circulat-ion time,the disturbance of internal environment gradually worsens when the blood supply of the limbs on the side of intubation is restored,especially when the extracorporeal circulation time exceeds 3 hours,the lactic acid（Lac）level is still relatively high even after the blood supply is restored for 1 hour.