A Pumping Intravascular Artificial Lung with Active Mixing

Intravascular, as well as extracorporeal, artificial lungs need to be effective and efficient in transferring both oxygen and carbon dioxide. This paper describes the preliminary development of a device that not only is efficient in gas transfer, but also can reduce any pressure loss by providing its own pumping action. The exchange surfaces of the device consist of many short, microporous, hollow fibers arranged in layers like the threads of a screw and placed in a cross-flow configuration. Rotation of the device greatly increases gas transfer efficiency, by increasing the relative velocity between the blood and the fiber surfaces, and pushes the blood along a path similar to that of an Archime-dean screw. In vitro water tests of prototype devices indicate that the rotation can enhance the gas transfer rates by as much as a factor of six. In vitro blood studies indicate moderate blood pumping against zero pressure head, a simulation of veno-venous bypass.