Inclusion Criteria:  Informed consent signed and dated by the investigator; and:  if patient is able to give consent: by the study patient if patient is unable to give consent: by the legal representative or if an emergency situation is determined: by an independent consultant physician Minimum age of 18 years  Study-specific:  Body weight greater than 40 kg Acute Kidney Injury (AKI) with clinical indication for CRRT Hypercapnia with indication for ECCO2R:  (paCO2 ≥ 55 mmHg at given ventilation parameters: tidal volume = 6 ml/kg PBW, PEEP to be adjusted according to the FiO2 , driving pressure < 15 cmH2O, max. inspiratory pressure < 30 cmH2O or TV=5 mmHg when max. inspiratory pressure< 30 cmH2O cannot be held)  Vascular access and Shaldon catheter allowing blood flow of 100 ml/min to 500 ml/min Arterial line in place, allowing blood sampling Estimated life expectancy greater than 3 days  Exclusion Criteria:  In case of female patients: pregnancy or lactation period (if patient is ≥ 55 years old or have been surgically sterilized, a negative pregnancy test is not required) Participation in an interventional clinical study during the preceding 72 hours Previous participation in the same study  Study-specific  Severe ARDS (Berlin definition): PaO2/FiO2 < 100 mmHg Intracerebral haemorrhage Intracranial hypertension Cardiogenic shock Acute myocardial infarction Hypersensitivity to heparin or known history of heparin induced thrombocytopenia (HIT Type II), if heparin is used as anticoagulant severe liver insufficiency or fulminant hepatic failure Uncontrolled bleeding and coagulation disorders, thrombocytopenia < 75000/nL Liver cirrhosis CHILD Pugh Classification > A BMI > 40 kg/m² Decision to limit therapeutic interventions