Controlling anticoagulation in extracorporeal blood circuits (hemoperfusion)

The study demonstrates that different individuals (monkeys) need different heparin doses so as to avoid either clotting or bleeding when an extracorporeal blood system is involved. The linear correlation between PT and WBPTT values enables to utilize the latter for monitoring the heparin level in the blood. One procedure is based on the application of the Gotch and Keen intravenous heparinization model in its steady state limit by utilizing the pre-treatment evaluation of k/S, the ratio of the elimination rate constant to the individual's sensitivity to heparin. A second procedure involves the direct heparinization of the extracorporeal system. The heparin infusion rate is monitored through the arterial WBPTT values after relating the individual's PT or WBPTT values to the in vitro heparin concentration in the blood. In vitro and in vivo study of the effect of hemoperfusion through a column containing anion exchange particles on the amount and rate of heparin administration indicates that only the in vivo results are meaningful. The sharp response of WBPTT to relatively small changes of citrate concentration in the blood precludes individual monitoring by WBPTT. Work on the advantage of utilizing heparin together with citrate is required.