Are standard human coagulation tests suitable in pigs and calves during extracorporeal circulation?

The thrombogenicity of membrane oxygenators as well as clotting parameters profiles, using standard human clotting tests, was analyzed in calves and p igs during 6 h perfusion. Three calves and 3 pigs were connected to extraco rporeal circulation with standard heparinization. Blood samples were taken for coagulation variables throughout perfusion, and oxygenators were examin ed for clot deposits at the end of the experiment. Two out of 3 oxygenators of the calf group presented clot deposits while none in the pig group did. Baseline coagulation variables of pigs showed values similar to those of h umans while neither extrinsic nor intrinsic pathways could be activated in calves with standard human coagulation tests. The calf model, in conclusion , was confirmed to be a difficult model for the testing of extracorporeal c irculation device resistance to thrombus formation, which is, however, not reflected by standard human coagulation tests. The pig model is a better mo del in which both coagulation pathways could be activated with standard hum an coagulation tests.