Impact of Cardiopulmonary Bypass Flow on Renal Oxygenation, Blood Flow and Tubular Injury

During open cardiac surgery, cardiopulmonary bypass (CPB) is used to temporarily replace the function of the heart and lungs. Renal ischemia resulting in acute kidney injury is common after cardiac surgery. The renal oxygenation is impaired during CPB, but the oxygenation may be improved by increasing the CPB blood flow. In this randomized study, two CPB flow rates will be compared regarding renal outcome (biomarkers and renal oxygenation/renal blood flow), as well as markers of inflammation and hemolysis. Additionally, urine oxygen tension will be measured during CPB and the early intensive care phase and compared to renal oxygenation. Regional oxygen saturation assessed with near infrared spectroscopy from the brain and kidneys will be monitored during and after surgery.