Occult intravascular clotting by means of intravenous injection of thrombin

Abstract

On infusing a dilute solution of thrombin intravenously into a dog at a constant and carefully regulated rate, no massive thrombosis occurs and no evidence of a thrombo-embolic state is obtained. An occult type of intravascular clotting is produced which is characterized by a progressive decrease of the level of fibrinogen, thrombocytopenia, a prolonged prothrombin time and a poor consumption of prothrombin. Labile factor (factor V) and thromboplastinogen (factor VIII) are strikingly diminished. Prothrombin is moderately decreased while stable factor (factor VII) and PTC (factor IX) are not significantly affected. It is postulated that the adsorption of thrombin to the fibrin fibrils which are filtered off in the capillary network and destroyed, constitutes the principal means for preventing dangerous accumulation of thrombin in the blood.