Ketamine and Kidney Injury in Cardiac Surgery

Inclusion Criteria: * Presenting for cardiac surgery at the Mayo Clinic in Rochester, Minnesota. * Scheduled to undergo complex cardiac surgery with the use of cardiopulmonary bypass. Complex cardiac surgery will be defined as surgery involving more than one heart valve, redo-sternotomy procedures, or combined valvular and coronary artery bypass graft procedures (aortic repair not excluded if meets other criteria). Exclusion Criteria: * Left or right ventricular assist device implantation or explantation. * Procedures not requiring cardiopulmonary bypass. * Active infection or sepsis requiring antimicrobial therapy and/or vasopressor therapy (treated endocarditis is not excluded). * Severe hepatic disease resulting in ascites. * Pre-operative significant renal dysfunction including a baseline creatinine equal to or greater than 2 mg/dL or requiring dialysis. * Immunosuppressive medication use (including current IV or oral steroids use, use of anti-rejection medications for transplant within 1 month, or chemotherapy within 6 months). * Immunodeficiency syndrome including HIV/AIDS, leukemia, and multiple myeloma