Modeling Blood Management and Hemolytic Risk in Pediatric Heart Surgery

Inclusion Criteria: * pediatric patients under 18 years of age undergoing cardiac surgery with clear prime on cardio-pulmonary bypass (CPB) at Boston Children's Hospital (BCH). Exclusion Criteria: * patients with known hemolytic disorders, patients on nitric oxide preoperatively, and patients found to have abnormal coagulation on routine preoperative assessment. Patients receiving heparin, American Society of Anesthesia (ASA) status, apixaban, warfarin, or bivalirudin held appropriately (i.e. for elective surgery) will not be excluded