This grant application purposes to further develop and evaluate an extracorporeal respiratory support device based on a new principle. This device achieves respiratory gas exchange by transporting across a hemodialysis membrane highly water soluble derivatives of the respiratory gases, namely hydrogen peroxide and bicarbonate ion. The associated accumulation in the blood of buffered hydrogen ion is neutralized by absorption of hydroxyl ion from the dialysis bath. Oxygenation is achieved by transmembrane catalysis of hydrogen peroxide. The dialyzer acts as a built in heat exchanger. A multidisciplinary program to design and evaluate this extracorporeal device for a variety of clinical uses is proposed. As part of the development of this device, basic research will be conducted on relevant aspects of membrane materials, catalysis, and biocompatibility. An improved mass spectrometer for continuous long term blood pO2 and pCO2 determination, using a small nonthrombogenic arterial catheter-sensor will be evaluated. The goal of this program project is a respiratory support system with a substantial performance and cost advantage over existing systems.