Study should demonstrate that alkaline phosphatase reduces the incidence and extent of acute kidney injury after cardiopulmonary bypass (CPB) as defined by the AKIN criteria.

After cardiac surgery under cardiopulmonary bypass (CPB) patients often show impairments of the immune system. Compared to placebo, CPB patients given alkaline phosphatase will have reduced composite endpoint of acute kidney injury (AKI), late extubation, gastrointestinal or neurological complications within 7 days and AKI within 90 days.

Inclusion Criteria:

• Undergoing cardiac surgery with planned cardiopulmonary bypass
• Additive Euroscore II ≥ 3 OR at least 3 surgical cardiac interventions are planned
• Ability to provide informed consent (not incapacitated)

Exclusion Criteria:

• Already on renal replacement therapy
• Patients with chronic kidney disease defined as estimated glomerular filtration rate [eGFR] < 30 mL/min/1.73 m2 [ CKD stage > 3 ]
• Patients who are pregnant or lactating
• Concurrent enrollment in another clinical trial
• Known allergic reaction to bovine alkaline phosphatase or patient is vegetarian or vegan
• Patients with ongoing infections or current use of steroids
• Patients with high-risk emergency surgery or with follow-up procedures already planned at admission (like e.g. TEVAR)