Abstract 16611: Higher Total Ultrafiltration Volume During Infant Cardiac Surgery is Associated With Acute Kidney Injury

Introduction: Many congenital heart centers use intraoperative ultrafiltration (UF) for fluid removal during and after infant cardiopulmonary bypass (CPB) surgery to reduce fluid overload. Excessive UF may result in intravascular hypovolemia. Postoperative acute kidney injury (AKI) is multifactorial, but little is understood about the role of UF on hypovolemia and postoperative AKI. Methods: This is a single center, retrospective review of infants receiving UF associated with CPB surgery. Patients requiring ECMO were excluded. UF volume (ml) was indexed to weight (kg). AKI was determined using the serum creatinine ‘Kidney Disease Improving Global Outcome (KDIGO)’ criteria or neonatal KDIGO (≤ 30 days of age) criteria. Multivariable logistic regression was used to adjust for multiple covariates associated with AKI. Results: From 6/2013 to 4/2015, 532 subjects <1 year of age underwent CPB-assisted congenital heart surgery with UF. Sixty-four (12%) subjects developed postoperative AKI. No patients required renal replacement therapy. Higher total indexed UF volume was associated with AKI (median 119 ml/kg [IQR 92-164 ml/kg] versus 97 ml/kg [72-128 ml/kg], p=0.001). Other univariate associations with AKI are listed in table 1. After adjusting for multiple covariates, higher indexed total UF volume was associated with increased AKI risk (OR 1.1, CI 1.03 - 1.17, p=0.005) for each additional 10 ml/kg UF volume. The only additional independently associated factor with AKI was higher vasoactive inotrope score on post-operative day 2 (OR 1.1, [1.04-1.17], p<0.001). Conclusions: While few patients developed postoperative AKI, higher intraoperative UF volume is associated with AKI risk. Postoperative hypovolemia due to excessive UF may be a modifiable AKI risk factor. Judicious use of postoperative UF may reduce AKI risk.