HEAT GENERATION AND HEMOLYSIS IN CENTRIFUGAL BLOOD PUMPS

Abstract

We investigated the effect of heat and friction around a shaft-sealing on hemolysis in centrifugal blood pumps. The materials were original pumps (Nikkiso HMS-15 and 3M Delphin), vane-removed pumps and a small chamber with a shaft coiled by a nichrome wire (mock pump) to investigate the effect of local heat on hemolysis. In-vitro hemolytic examination was carried out using heparinized fresh blood of a goat. The original pumps were driven at the flow rate of 5L/min and pressure head of 500mmHg, The vane-removed pumps were driven at the same rotation number and the flow of 5L/min was maintained by Bio-pump (1000rpm). Electric power of 0.05, 2 and 10 Watts was supplied to the mock pump and the flow was maintained in the same way. We also measured generated heat of the original pumps and vane-removed pumps with a thermally-insulated water chamber. The results indicated that the heat generated around the shaft-sealing was minimal. The hemolysis of the shaft-sealing was, however, considerable but not principal. The local heat less than l0 Watts did not affect hemolysis. We concluded that a shaft-sealing affects hemolysis by not local heat but the friction, and the main causative factor of hemolysis was supposed to be hydraulic energy loss such as shear stress.