Investigation of coagulopathy in three cases of tiger snake (Notechis ater occidentalis) envenomation.
OBJECTIVE
To investigate the severe coagulopathy (fibrinogen < 1.0 g/l) that occurs in some cases of tiger snake envenomation. Specifically, to determine the concentration of clotting factors on presentation and during resolution of the coagulopathy.


METHODS
Clotting factors II, V, VII, VIII, IX, XI were assayed on all coagulation samples received from three successive cases of severe tiger snake envenomations. Assays were performed at dilutions of 1:5 and 1:10 using an MLA 1600c automated coagulation analyser and Dade Behring factor-deficient plasmas, controls and standards. D-dimers were assayed using Agen Dimertest latex kit, fibrinogen was determined using the Clauss method and platelet counts were performed using Abbott Cell-Dyn 4000 analysers.


RESULTS
The activity of the coagulation factors of the intrinsic pathway was reduced (factor VIII < 44% in all cases, factor IX < 33%, factor XI < 52% in Cases 1 and 2) but the results for the two dilutions were not parallel. In one case, factor VIII and factor IX activity increased 2-fold prior to the administration of blood products. Treatment with blood products corrected the coagulation indices in two out of the three cases but factor V remained low in one case (25%).


CONCLUSIONS
The non-parallel results and the apparent increase in factor levels prior to treatment may result from the transient presence of an inhibitor to factors VIII, IX and XI in cases of tiger snake envenomation. Insight into the effects of snake venom on individual coagulation factors could be beneficial when considering new treatments for the coagulopathy induced by snake envenomation.
Ferguson
Lucy A
LA
Haematology Department, Royal Perth Hospital, Western Australia.
Morling
Alan
A
Moraes
Caroline
C
Baker
Ross
R
D000328:Adult; D000818:Animals; D000997:Antivenins / Q000627:therapeutic use; D001778:Blood Coagulation Disorders / Q000097:blood / Q000139:chemically induced* / Q000188:drug therapy; D001779:Blood Coagulation Factors / Q000032:analysis; D016913:Blood Component Transfusion; D002648:Child; D004546:Elapid Venoms / Q000009:adverse effects*; D017815:Elapidae; D005169:Factor VIII / Q000627:therapeutic use; D017809:Fatal Outcome; D005340:Fibrinogen / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D012909:Snake Bites / Q000097:blood / Q000150:complications* / Q000188:drug therapy
D000997:Antivenins; D001779:Blood Coagulation Factors; D004546:Elapid Venoms; C026912:cryoprecipitate coagulum; D005169:Factor VIII; D005340:Fibrinogen