Performance of fluid balance as a marker of acute kidney injury in children after open heart surgery

Abstract

Acute kidney injury (AKI) is a serious complication in the perioperative period and is consistentlyassociated with increased morbidity and case fatality rate. This has been best studied in the car-diac surgery setting where it has been shown that up to 11.5–86.0% of patients exposed tocardiopulmonary bypass (CPB) will develop AKI, with 2.0–18.9% requiring renal replacementtherapy (RRT). A prospective uncontrolled cohort study was conducted between 2011 and 2015,in which 93 children with various congenital heart lesions undergoing CPB were enrolled. Serumcreatinine (SCr) level was determined by Jaffé’s method (Cobas 6000 analyser, Roche). Postop-erative fluid balance was estimated as the difference between fluid intake and output. Data forfurther processing were retrieved from anaesthesia and intensive care data management systemflowsheets (IntelliView, Philips). AKI developed in 42 patients (45.6%) by meeting at least KDIGO(Kidney Disease: Improving Global Outcomes) stage I criteria (with SCr rise by more than 50%from the baseline). Thirty eight patients complied with the 1ststage of AKI, three with 2ndstageand two with 3rdstage, according the KDIGO classification and staging system. One patient hav-ing severity stage II and two patients having severity stage III of AKI required initiation of RRT us-ing peritoneal dialysis. Two patients from the RRT group survived, one died. The medianintraoperative urine output was 2.32 ml/kg/h, (range from 0.42–5.87 ml/kg/h). Median CPB timewas 163 min., median aortic cross-clamping time was 97.9 min., cooling during CPB to 29.5 °C.The diagnosis of AKI using SCr was delayed by 48 hours after CPB. Median fluid balance (FB) onthe first postoperative day in non-AKI patients was 13.58 ml/kg (IQR 0–37.02) vs 49.38 ml/kg(IQR 13.20–69.32) in AKI patients,p< 0.001. AKI is a frequent complication after open heart sur-gery in children with congenital heart lesions. From 93 patients included in the study, 42 (45.2%)met at least KDIGO Stage I criteria for AKI. FB is a sensitive marker of kidney dysfunction. Me-dian FB in the 1st postoperative day significantly differed between AKI patients: 49.38 ml/kg(13.20–69.32) versus 13.58 ml/kg in patients with intact kidney function (AUC = 0.84;p= 0.001).Thus it can be used as a marker of AKI.