TANDEM OPERATION OF A TURBO BLOOD PUMP (BP-80-TYPE CENTRIFUGAL PUMP) TO REDUCE HEMOLYSIS

When operating turbo blood pumps in tandem, the strength of shear stre ss is reduced, but the exposure duration of the stress is increased. T he purpose of this experiment was to compare the degree of contributio n of these two factors on hemolysis as well as to evaluate the effecti veness of the tandem operation of turbo blood pumps. Tandem operation of two Bio-pumps (BP-80; Medtronics Bio-medicus, Inc., Eden Prairie, M innesota, U.S.A.) were compared with single operation of a BP-80 in in vitro hemolysis tests in three different driving conditions, that is, pumping heads of 200, 350, and 500 mm Hg under a pump flow rate of 5 L/min. The Allen's hemolytic indexes of the tandem operation at pumpin g heads of 200, 350, and 500 mm Hg were 0.014, 0.020, and 0.080 mg/dl, respectively. The hemolytic indexes of the single operation at pumpin g heads of 200, 350, and 500 mm Hg were 0.014, 0.056, and 0.12 mg/dl, respectively. These results indicate that tandem operation is a useful method of reducing hemolysis with the BP-80 under high pumping heads and that the effect on hemolysis of exposure to higher shear stresses may be more serious than that of longer durations of exposure to shear stress in turbo blood pumps.