An intravascular blood-gas exchanger (10) includes a plurality of gas permeable tubes or fibers (12) that are connected to a central gas conduit (16). The gas permeable tubes allow oxygen to be transferred into a patient's blood and carbon dioxide removed. The gas permeable tubes are preferably formed into one or more generally conical-shaped segments that can be selectively moved between a retracted position (fig.1), which allows the intravascular blood-gas exchanger to be inserted or removed from the patient, and an expanded position (fig.2) after the device is inserted into the patient and positioned such that the tubes are generally arranged in a predetermined pattern. The gas permeable tubes are preferably arranged to improve the flows of blood around the tubes and increase the gas transfer rate. The device in its retracted (furled) condition is small enough in cross-sectional diameter to be inserted, percutaneously and without the need for major invasive vascular surgery, in a blood vessel.
