Number of patients n = 20 Interventions 1. With ongoing continuous hemofiltration and mechanical ventilation additional membrane gas exchange device (Prismalung®) in the renal replacement circulation; measurements of the effects on PaCO2 under varying blood and sweep gas flows 2. Afterwards, reduction of the tidal volume (VT) / plateau pressure until reaching the initial PaCO2value Study drug None Primary endpoint 1. Changes in the PaCO2 / acid-base status (BGA) 2. Changes of the VT / plateau pressure in the ventilation (ventilation settings) Secondary endpoints Changes in the systemic hemodynamics Vasopressor dosage BGA, renal values, lactate PaCO2 before and after gas exchange device Lifetimes of the extracorporeal circulation Complications Study site Intensive care units Medizinische Klinik 4, Uniklinikum Erlangen-Nürnberg Medizinische Klinik 4, Klinikum Nürnberg Süd Klinik für Intensivmedizin Universitätsklinikum Hamburg Eppendorf Klinik für Anästhesiologie und Intensivmedizin Universitätsklinikum Frankfurt a. M. Timeline Start in October 2015 Anticipated study duration: 6 months Financing Baxter Gambro Renal GmbH (Ltd)