Acute kidney injury (AKI) after cardiopulmonary bypass (CPB) in infants is common and associated with poor outcomes. Peritoneal dialysis (PD) and furosemide have been used to attain negative fluid balance due to AKI induced oliguria, but have not been compared prospectively. The investigators will prospectively compare outcomes of infants with oliguria after CPB randomized to PD vs. furosemide with the hypothesis that infants receiving PD have superior outcomes.