COMPARATIVE HEMOLYSIS STUDY OF CLINICALLY AVAILABLE CENTRIFUGAL PUMPS

Centrifugal pumps have become important devices for cardiopulmonary by pass and circulatory assistance. Five types of centrifugal pumps are c linically available in Japan. To evaluate the blood trauma caused by c entrifugal pumps, a comparative hemolysis study was performed under id entical conditions. In vitro hemolysis test circuits were constructed to operate the BioMedicus BP-80 (Medtronic, BioMedicus), Sarns Delphin (Sarns/ 3M Healthcare), Isoflow (St. Jude Medical [SJM]), HPM-15 (Nik kiso), and Capiox CX-SP45 (Terumo). The hemolysis test loop consisted of two 1.5 m lengths of polyvinyl chloride tubing with a 3/8-inch inte rnal diameter, a reservoir with a sampling port, and a pump head. All pumps were set to flow at 6 L/min against the total pressure head of 1 20 mm Hg. Experiments were conducted simulta neously for 6 h at room t emperature (21 degrees C) with fresh bovine blood. Blood samples for p lasma-free hemoglobin testing were taken, and the change in temperatur e at the pump outlet port was measured during the experiment. The mean pump rotational speeds were 1,570, 1,374, 1,438, 1,944, and 1,296 rpm , and the normalized indexes of hemolysis were 0.00070, 0.00745, 0.000 96, 0.00066, 0.00090 g/100 L for the BP-80, Sarns, SJM, Nikkiso, and T erumo pumps, respectively. The change in temperature at the pump outle t port was the least for the Nikkiso pump (1.8 degrees C) and the most with the SJM pump (3.8 degrees C). This study showed that there is no relationship between the pump rotational speed (rpm) and the normaliz ed index of hemolysis in 5 types of centrifugal pumps. The pump design and number of impellers could be more notable factors in blood damage .