In vitro study of hemolysis induced by flow-regulated and pressure-dependent flow pumps.

In vitro experiments showed that a pressure-dependent flow pump which "obeys Starling's law" (with flexible tube stretched on vertical rotor) was less hemolytic than a classical flow-regulated pump (with pump inset occluded between a rotor and a stator). The degree of hemolysis obtained with fresh human blood was higher with blood from chronic respiratory patients than with blood from normal donors. Also, the hemolysis was less with fresh heparinized blood than with stored ACD blood, and less with normal blood than with diluted blood. Comparing hemodialysis pumps with ECC pumps showed that hemolysis tripled with the pressure-dependent flow types and was 30 times higher with the classical pumps.