Total erythrocyte destruction time: the new index for the hemolytic performance of rotary blood pumps.

To date an index of hemolysis is the only parameter to evaluate in vitro the hemolytic properties of blood pumps. However, this index does not reflect the sublethal conditions of erythrocytes. In this paper, a new concept, the total destruction of erythrocytes, to indicate traumatic features on erythrocytes is proposed. Five paired long duration in vitro hemolysis tests were conducted using the BioMedicus pump; BP80, and the Nikkiso pump, HMS12. The pumps ran until either a sudden change in blood color to dark red was noted or the pumps ran for over 24 h. At a certain point, the plasma-free hemoglobin levels suddenly and dramatically increased in each experiment except one Nikkiso case. At a certain point in time, the destruction of most erythrocytes suddenly and simultaneously occurred. We call this phenomenon total destruction of erythrocytes and define the pumping duration required to raise the level of the plasma-free hemoglobin to 50% of the total hemoglobin as total destruction time. Although there is no statistical difference in the normalized index of hemolysis between the two pumps, the total destruction time of the BioMedicus pump is significantly shorter than that of the Nikkiso pump. It appears that an accumulation of sublethal damage on erythrocytes resulted in the decrease of the hemolytic threshold of the entire erythrocyte and also resulted in a sudden entire destruction of erythrocytes.