Effect of extracorporeal enzymatic deheparinization on formed blood components

A stirred blood filter containing an immobilized enzyme, heparinase, has been used to neutralize heparin's anticoagulant activity at the outflow of an extracorporeal circuit in dogs. The hematocrit and red blood cell count remained unchanged throughout the 90-min perfusion period. Platelet and white blood cell counts decreased early in the procedure to approximately 20% of the initial levels, but then returned to 30 and 70%, respectively, of their initial values by the end of the procedure. After 24 h normal levels were reestablished. In vitro experiments with human blood were conducted to determine the principal cause of the observed decrease of formed blood components. An unstirred heparinase filter preserved platelets and white blood cells better than stirred filters possessing higher, the same, or no heparin-degrading capacity, suggesting that most of the loss of formed blood components is due to stirring and not to the heparinase or the Sepharose support on which the enzyme is immobilized.