A TEASPOON PUMP FOR PUMPING BLOOD WITH HIGH HYDRAULIC EFFICIENCY AND LOW HEMOLYSIS POTENTIAL

Virtually all blood pumps contain some kind of rubbing, sliding, close ly moving machinery surfaces that are exposed to the blood being pumpe d. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The orig inal teaspoon pump design prevented the rubbing, sliding machinery sur faces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to ''slip around'' the rotating impell er so that the blood itself never rotated fast enough to develop adequ ate pressure. An improved teaspoon blood pump has been designed and te sted and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating ''swinging'' hose as the pu mp impeller. The fluid enters the pump through the center of the swing ing hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that i s comparable to a flexible garden hose. If the free end of the hose we re swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impel ler itself did not ''rotate''; therefore, no rotating shaft seal or in ternal bearings are required.