Catheter with semipermeable membrane for treatment of severe pulmonary emboli

A catheter system for treating pulmonary emboli has a multi-lumen primary catheter for accessing the vascular system. The primary catheter has a balloon on the distal end for occluding the venous tree, preferably distal to the renal veins. A semipermeable membrane is attached to the primary catheter intermediate the balloon and the proximal end of the primary catheter. Oxygen is supplied to the membrane through the primary catheter to enrich the blood in the venous tree flowing to the heart. Other lumen in the primary catheter guide other catheters through the heart to the pulmonary arteries to inject lysing agents, contrast media, medicaments and to remove blood clots and other catheters may extend through the vena cava to other parts of the venous tree to supply the same agents and to remove blood clots there.