Prolonged Hypofibrinogenemia and Protein C Activation after Envenoming by Echis Carinatus Sochureki

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  • University of Utah School of Medicine, and the Veterans Administration Medical Center, Salt Lake City, Utah
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Following envenomization by Echis carinatus sochureki, a professional snake handler developed a profound coagulopathy manifested by hemorrhage from the bite site, venipuncture sites and gums; coagulation testing revealed prothrombin and partial thromboplastin times greater than 150 seconds, a fibrinogen of 0 mg%, and marked elevation of fibrin degradation products. In addition, protein C antigen levels were undetectable. The coagulopathy was treated with cryoprecipitate; two different antivenoms were also administered with uncertain benefit. Subsequently, the properties of the venom and antivenoms were studied. Venom did not directly clot fibrinogen; however, venom concentrations as low as 0.2 µg/ml caused significant prothrombin activation. In addition, venom activated protein C in the absence of thrombomodulin, and this activity was inhibited by hirudin. The ability of four commercial antivenoms to neutralize the venom prothrombinase and hemorrhagic activity was measured. Three of the four antivenoms partially neutralized venom-induced prothrombin activation. Extreme differences in efficacy were found among the four antivenoms in neutralizing venom hemorrhagic activity in mice. This case illustrates the difficulty in managing the complex coagulopathy that can result from exotic snake envenomization, and identifies a new coagulant property of Echis carinatus venom (protein C activation).