This invention provides an assay to monitor antithrombic activity of a Factor IXa compound infused into circulation of a patient which includes: (a) obtaining Factor IXa-deficient plasma; (b) mixing the plasma from step (a) with diatomaceous and with plasma from the patient; (c) incubating the mixture...http://www.google.com/patents/US5839443?utm_source=gb-gplus-sharePatent US5839443 - Method for inhibiting thrombosis in a patient whose blood is subjected to extracorporeal circulation 
