Selection Of Perfusion Flow In Cardiopulmonary Bypass Surgery For Adult Patients With Valvular Heart Disease

Background valvular heart disease（VHD）is a normal mitral,aortic,and tricuspid valve and pulmonary valve due to rheumatic fever,degeneration,mucous,ischemia,necrosis,trauma,infection,congenital anomalies of the lesions,these lesions makes the valve of the original shape,size,structure and surrounding tissue abnormalities,which not only affect the direction of blood flow dynamics,and heart valve after long organization change,lead to cardiac function disorder,eventually lead to cardiac insufficiency or even heart failure.Extracorporeal circulation is nearly half a century of a new 1953 Gibbon successfully implement the first clinical extracorporeal circulation operation,with the release different new extracorporeal circulation machine,surgeons and extracorporeal circulation doctor the steady accumulation of experience in the process of operation,extracorporeal circulation technology changed with each passing day,is no longer a simple supported by intraoperative circulation,temporarily replace cardiopulmonary function to complete the operation,but the extracorporeal circulation in the flow of control,the balance of electrolyte,the protection of cardiac function,and put forward higher requirements for the protection of brain function.Currently recognized safety extracorporeal circulation intraoperative aortic perfusion flow of 50 ml/min.kg-80 ml/min.Kg,and the extracorporeal circulation operation process,how the flow changes affect the different moment of electrolyte of different parameters,such as the local metabolism of the brain,thereby further for clinical extracorporeal circulation in different times a reliable basis for choosing the right aortic perfusion flow.Objective To study the effect of flow rate on pH,urine volume and cerebral oxygen saturationduring cardiopulmonary bypass（CPB）in patients with valvular heart disease.Methods Perfusion flow group basis:50-60ml/min.Kg for low flow group,70-80ml/min.Kg for high flow group;The 20 patients in our hospital were selected to have a continuous flow rate of 50 to 60ml/min.In this study,20 patients with age of 16 years or older were selected,and the perfusion flow rate was 70 to 80ml/min.Kg group was recorded as high flow group（n=20）and low flow group（n=20）.The cerebral oxygen saturation value,lactic acid,BE value and the amount of urine between the two groups after induction of anesthesia（T₁）,the beginning of CPB（T₂）,5min after declamping shock（T₃）,5MIN after recovery temperature（T₄）,5MIN after aortic opening（T₅）,5MIN after the end of aortic bypass（T₆）were compared.Results（1）After the induction of anaesthesia（T1）to the aorta block 5 min（T3）,the BE value of high-flow group was decreased;The low flow group showed an elevated trend and exceeded 3mmol/l in the aorta for 5 min（T3）.The aorta blocked 5 min（T3）to the recovery temperature 5 min（T4）high flow group and low flow group BE both increased and reached the peak at the recovery temperature of 5 min（T4）.The recovery temperature was 5 min（T4）to aorta open 5 min（T5）and the low flow group was decreased.（2）The level of lactic acid in the high-flow group was decreased after anesthesia induction（T1）to aortic block 5 min（T3）.The low flow group showed an increasing trend;Aortic block 5min（T3）to restore the temperature for 5 min（T4）high flow and low flow group lactic acid levels were elevated and the peak of the recovery temperature for 5min（T4）,but high flow increase is greater than the low flow group;The recovery temperature was 5 min（T4）to aorta open 5 min（T5）,and the lactate level of both high flow group and low flow group decreased.（3）After anesthesia induction（T1）to aorta block 5 min（T3）high flow group and low flow group urinary volume showed an upward trend,and the increase was almost the same.The aorta blocked 5 min（T3）to the recovery temperature of 5 min（T4）,and the urine volume of high-flow group and low-flow group increased and reached the maximum difference at the recovery temperature of 5 min（T4）.The recovery temperature was 5 min（T4）to aorta open 5 min（T5）,and the urine volume of both high flow group and low flow group continued to increase.（4）the aorta block 5 min（T3）to restore the temperature for 5 min（T4）,two groups of cerebral oxygen saturation difference began to increase,the recovery temperature for 5 min（T4）to the aorta open 5 min（T5）two group of cerebral oxygen saturation value decreases,and the recovery temperature 5 min（T4）the biggest difference.（5）HCT 5 min after blocking time difference（T3）,and in the complex temperature 5 min（T4）maximum difference,high flow set at this time there was a low,and the aorta open 5 min（T5）difference decreases.（6）The differences in arterial occlusion of 5min（T3）were observed,and the difference was highest in 5min（T4）,with the lowest in the low flow group,and 5min（T5）in aorta opening.Conclusion High flow group to aortic open after aorta block can increase the local cerebral metabolism,increase oxygen supply,reduce blood lactic acid level,balance ph value,increase renal blood flow perfusion,but at the same time it increases blood damage at the complex temperature;The low flow group reduced the local cerebral metabolism during the aorta occlusion,and decreased the cerebral oxygen supply,the lactic acid level was increased,the ph was unbalanced,and the renal blood perfusion was insufficien,but at the same time,it is good to avoid a lot of blood damage at the complex temperature stage.It is also the moment of greatest difference in blood damage.First block of 5 minutes is one of the largest moment,variations in acid and alkali recovery temperature after 5 minutes is the largest gap between urine volume and cerebral oxygen saturation point,so in blocking aorta to the aorta open the three critical moment,choose high flow perfusion is of great significance,But at the same time,pay attention to the protection of blood in the warm stage.Since the CPB has not yet started,there is no difference between high and low flow rate.T2-T3 has a relatively small difference in the selection of high and low flow due to the short time.T3-T4 if HCT height selected high flow perfusion;T3-t4 if HCT is not high in the selection of flow perfusion;T4-t5 selects high flow rate;T5-t6 is the difference between high and low flow before CPB ends.