Clinical Analysis Of Postoperative Mortatity And Severe Hypoxemia In Patients With Stanford Type A Aortic Dissection

Hypoxemia following surgical repair of aortic dissection is a common and life-threatening complication.Hypoxemia seriously affects the patient’s prognosis,and even leads to death.The cause and mechanism of hypoxemia after surgical repair are not completely clear,and treatment strategy of hypoxemia is also very thorny.There is an urgent need for further study.Objective:To analyze the causes of early postoperative death in patients with Stanford type A aortic dissection,and to explore the risk factors of postoperative severe hypoxemia.Methods:1.Analysis the causes of early death after surgery for Stanford type A aortic dissection.The clinical data of 162 surgically treated patients with Stanford type A aortic dissection in our hospital from January 2016 to March 2019 were retrospectively summarized,and the causes of early postoperative death were analyzed.2.Clinical analysis of severe hypoxemia after surgery for Stanford type A aortic dissection.From January 2016 to March 2019,162 patients with Stanford type A aortic dissection were analyzed retrospectively.Among them,24 cases were underwent moderate hypothermia cardiopulmonary bypass,138 cases were deep hypothermia circulatory arrest and selective antegrade cerebral perfusion for brain protection.According to the PaO₂/FiO₂ of the patients72 hours after operation,PaO₂/FiO₂≤100mmHg was the severe hypoxemia group（n=82）,PaO₂/FiO₂>100mmHg was the non-severe hypoxemia group（n=80）.Using the SPSS 20.0software for statistical analysis,perioperative clinical data were analyzed and compared between the two groups.It was performed to identify risk factors of postoperative serve hypoxemia after surgery.3.Observation serum inflammatory factors of hypoxemia in patients with aortic dissection before surgery.From November 2019 to March 2020,39 patients with acute aortic dissection were selected;including 20 patients with Stanford type A,19 patients with Stanford type B,32males and 17 females,with an average age of 54.7 years.Patients with preoperative oxygenation index≤300mmHg were defined as hypoxemia.According to this definition,the patients were divided into two groups:preoperative hypoxemia group 19（48.7%）and preoperative non-hypoxemia group 20（51.3%）.Venous blood samples were taken from patients after admission.The levels of serum interleukin-6（IL-6）,tumor necrosis factorα（TNF-α）and interleukin-8（IL-8）were measured by FCM.Results:1.Analysis the causes of early death after surgery for Stanford type A aortic dissection.19（11.7%）patients died in hospital after operation.The causes of death were:9 cases of multiple organ dysfunction syndrome,which was the first cause of death in this group,accounting for 47.4%;4 cases of septic shock,accounting for 21%;2 cases of low cardiac output syndrome and 2 cases of ischemic hypoxic encephalopathy,each accounting for 10.5%;1 case of massive gastrointestinal hemorrhage and 1 case of sudden cardiac death,each accounting for 5.3%.Compared with the survival group,the age of patients in the death group was significantly higher（P<0.05）,the proportion of BMI≥24kg/m²,preoperative coronary heart disease,WBC>15×10⁹/L,ALT>40U/L in the death group was significantly higher than that in the survival group（P<0.05）,and the diameter of aortic root and ascending aorta in the survival group was significantly higher than that in the death group（P<0.05）,the amount of RBC input during operation and 48 hours after operation in the death group was significantly higher than that in the survival group（P<0.05）,and the incidence of postoperative complications（gastrointestinal hemorrhage,encephalomyelitis）in the death group was significantly higher than that in the survival group（P<0.05）.2.Clinical analysis of severe hypoxemia after surgery for Stanford type A aortic dissection.There were 162 patients（115 males and 47 females）,aged from 23 to 77 years,with an average age of（50±11）years.There were significant differences in age,BMI>24kg/m²,preoperative hypertension and Marfan’s syndrome between the two groups（P<0.05）.There were 22 cases of Marfan syndrome with an average age of（36±8）years.The patients in the acute and subacute stage of operation in the severe hypoxemia group were significantly higher than those in the non-severe hypoxemia group（P<0.05）.The preoperative oxygenation index of severe hypoxemia group was less than 300mmHg,preoperative lactate,D2 polymer,preoperative SCr>105umol/L,preoperative ALT>40U/L were significantly higher than those of non severe hypoxemia group（P<0.05）.In severe hypoxemia group,the lowest hematocrit and the end of cardiopulmonary bypass hematocrit were significantly lower than those in non severe hypoxemia group（P<0.05）,and the CPB time,the amount of concentrated red blood cell input during operation,the amount of recovered self blood and the amount of in and out during operation were significantly higher than those in non severe hypoxemia group（P<0.05）.19（11.7%）patients died in the early postoperative period,severe hypoxemia group14（17.1%）was significantly higher than that in non-severe hypoxemia group 5（6.1%）（P<0.05）;the duration of ICU,postoperative hospitalization,mechanical ventilation and postoperative red blood cell input in patients with severe hypoxemia were significantly higher than those in patients with non-severe hypoxemia（P<0.05）.The number of dialysis patients was significantly higher than that of non severe hypoxemia group;the incidence of postoperative complications（acute renal failure and pleural effusion）in patients with severe hypoxemia was significantly higher than that in patients with non-severe hypoxemia（P<0.05）.Multivariate logistic regression analysis showed that BMI>24kg/m²[OR=2.604,95%CI（1.055-6.427）;P=0.038],PaO₂/FiO₂≤300mmHg[OR=2.963,95%CI（1.283-6.841）;P=0.011]and CPB time>195min[OR=1.007,95%CI（1.000-1.014）;P<0.044]were significantly correlated with postoperative severe hypoxemia.3.Observation serum inflammatory factors of hypoxemia in patients with aortic dissection before surgery.There was no significant difference in age,gender,height,BMI,Stanford classification,time from symptom attack to operation,smoking history,preoperative complications,heart and large blood vessel operation history,preoperative ultrasound results,preoperative laboratory examination（except WBC）between the preoperative hypoxemia group and the preoperative non-hypoxemia group（P>0.05）.Comparison of inflammatory indexes:the ratio of IL-6,TNF-α,WBC>15×10⁹/L in patients with preoperative hypoxemia group was significantly higher than that in patients with preoperative non-hypoxemia group（P<0.05）.Conclusion:1.The causes of death in this group included multiple organ dysfunction syndrome,septic shock,low cardiac output syndrome,hypoxic ischemic encephalopathy,massive hemorrhage of digestive tract,sudden cardiac death.The patients were fully evaluated before operation,the operation strategy was constantly improved,the operation and cardiopulmonary bypass time were shortened,the ischemia-reperfusion injury of each organ was reduced,and the complications after operation were actively and effectively prevented and treated It is the key to prevent early death of patients with aortic dissection.2.BMI>24kg/m²,PaO₂/FiO₂≤300mmHg,CPB time>195min are independent risk factors of severe hypoxemia after Stanford A aortic dissection.It may be helpful to avoid the occurrence of severe hypoxemia after operation by reducing the time of cardiopulmonary bypass and operation,accurate hemostasis and reducing the use of blood products.3.The WBC count,serum IL-6 and TNF-αwere significantly increased in patients with hypoxemia before operation,suggesting that AD can induce systemic inflammatory response.Inhibition of inflammatory response may be helpful to improve the preoperative hypoxemia of patients with aortic dissection.