Predictive Value Of Renal Regional Tissue Oxygen Saturation On Postoperative Acute Kidney Injury In Children With Complex Congenital Heart Disease

Objective:To investigate the predictive value of renal regional tissue oxygen saturation（RrSO₂）on postoperative acute kidney injury（AKI）in children with complex congenital heart disease（CHD）.Methods:We randomly selected 36 children（22 males and 14 females）of age≤1 year with complex congenital heart disease（CHD）who complied with the risk adjustment in congenital heart surgery method（RACHS）II-III.All cases were operated successfully under the cardiopulmonary bypass（CPB）.Clinical characters of children:diagnosis,gender,age of the month,weight,preoperative creatinine（Cr）value,preoperative pulse oximetry（SpO₂）,the lowest intraoperative pharyngeal temperature,the urine output during the operation,CPB time,operation time and the tracheal extubation time were recorded.Renal regional tissue oxygen saturation（RrSO₂）,mean arterial pressure（MAP）and pharyngeal temperature were recorded at following time points:five minutes after tracheal intubation（T₁）,five minutes after ascending aortic clamping（T₂）,five minutes after ascending aorta opening（T₃）,at the end of CPB（T₄）,at the end of ultrafiltration（T₅）,3 hours after CPB（T₆）,8 hours after CPB（T₇）and 24 hours after CPB（T₈）.Arterial blood,central venous blood extracted,arterial oxygen saturation（SaO₂）,arterial blood lactic acid（Lac）,arterial hemoglobin concentration（Hb）,central venous oxygen saturation（ScvO₂）according to the blood gas analysis at T₁,T₂,T₃,T₄,T₅,T₆,T₇,T₈were recorded.The levels of Cr in blood were recorded before and 1,2,3,4,5,6,7 days after surgery.The children were divided into the acute kidney group（group I）and the normal group（group N）according to the diagnostic criteria of Kidney Disease:Improving Global Outcomes（KDIGO）and the renal function status of the children in group I was recorded in seven days.Compare the clinical characters and MAP,pharyngeal temperature,Hb,SaO₂,RrSO₂,Lac and ScvO₂ at different time points in the two groups of children.Significant variables between two groups were analyzed by binary logistic regression analysis,using receiver operating characteristics（ROC）curve analysis to get the predictive value of RrSO₂ for AKI.Results:（1）A total of 36 children with complex CHD were included in this study,including8 cases of complete aortic transposition,8 cases of complete endocardial cushion defect,10 cases of Fallot tetralogy,and 10 cases of ectopic pulmonary vein drainage.22 males and 14 females with month age of（3.5±2.7）months,weight（4.7±1.1）kg,CPB time（116.89±35.19）min and operation time（220.28±59.27）min.All twelve children in group I were diagnosed with AKI stage 1.The highest Cr value was（79.20±13.30）umol/L within 7 days after surgery.AKI occurred at（2.00±0.82）days after surgery.Six cases returned to normal Cr levels within 7 days.All children did not receive renal replacement therapy.There were no significant differences in the types of congenital heart disease,gender,age of the month,weight,SpO₂,preoperative Cr value,intraoperative lowest pharyngeal temperature,intraoperative urine output,CPB time,operation time and extubation time between the two groups（P>0.05）.（2）The levels of RrSO₂ in group I were significantly lower than those in group N at T₃,T₄,T₅,T₆（all P<0.01）.The levels of RrSO₂ between two groups at T₁,T₂,T₇ and T₈did not show significant differences（all P>0.05）.There were no significant differences in MAP,pharyngeal temperature,SaO₂,Hb,Lac,ScvO₂ between the two groups at each time point（all P>0.05）.（3）The results of binary logistic regression analysis showed that RrSO₂ at T₃（OR=0.337,95%CI 0.123⁰.923,P=0.034）,T₄（OR=0.637,95%CI 0.417⁰.974,P=0.037）,T₅（OR=0.685,95%CI 0.479⁰.980,P=0.038）,T₆（OR=0.736,95%CI0.554⁰.980,P=0.036）were risk factors for postoperative AKI in children with complex CHD.（4）ROC curve analysis shows that when the RrSO₂ is 60.2%,57.2%,55.0%and54.0%at T₃,T₄,T₅,T₆ respectively.The sensitivity is 66.7%,83.3%,66.7%and 83.3%,respectively.The specificity is 100%,91.7%,100%and 75%,respectively.The areas under the AUC curve were 0.896,0.861,0.792,and 0.840,respectively.Conclusion:RrSO₂ has a predictive value on the postoperative AKI in children with complex CHD from ascending aortic opening to 3 h after CPB;it is recommended that the level of RrSO₂ should be maintained above 60.2%during this period which will be helpful for reducing the incidence of postoperative AKI.