Predictive value of BMI combined with preoperative oxygenation index for postoperative hypoxemia in Stanford type A aortic dissection / 解放军医学杂志

ABSTRACT

Objectives To analyze the risk factors and their predictive value for postoperative hypoxemia in Type-A aortic dissection(TAAD).Methods A single-center retrospective study was conducted among 146 consecutive patients diagnosed as TAAD and undergone aortic arch surgery from January 2018 to June 2021 in Nanfang Hospital of Southern Medical University.According to the lowest postoperative PaO2/FiO2 ratio within 24 hours,the patients were classified into two groups:hypoxemia group(PaO2/FiO2≤200 mmHg)and non-hypoxemia group(PaO2/FiO2>200 mmHg).The difference of preoperative oxygen index,duration of mechanical ventilation and mortality in hospital were analyzed between the two groups.The independent risk factors for postoperative hypoxemia were evaluated by multivariate logistic regression and the predictive value was analyzed by receiver operator character(ROC)curves.Results For TAAD patients,the incidence of postoperative hypoxemia was 45.9%.Compared to non-hypoxemia group,hypoxemia group exhibited longer duration of mechanical ventilation(P<0.001)and longer intensive care unit(ICU)length of stay(P<0.05).Moreover,patients with hypoxemia presented higher mortality during hospital(P=0.011).Multivariate regression analysis identified BMI as independent risk factor(OR=1.701,P<0.001)and preoperation PaO2/FiO2 ratio as protective factors for postoperative hypoxemia in patients with TAAD(OR=0.987,P=0.004).Area under the ROC curve of BMI was 0.848,the optimal cut-off point of BMI was 25.8 kg/m2.Area under the ROC curve of pre-operation PaO2/FiO2 ratio was 0.808,the optimal cut-off point of preoperation PaO2/FiO2 ratio was 265 mmHg.Conclusions BMI higher than 25.8 kg/m2 is an independent risk factor and preoperation PaO2/FiO2 ratio higher than 265 mmHg is a protective factor for postoperative hypoxemia in patients with TAAD.Subjects with hypoxemia had longer duration of mechanical ventilation,ICU stay and higher mortality.