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Blood Clotting Profiles in the Management of Copperhead Snake Bites
This post is mostly for the doctors, but may be of interest to herpetologists and others interested in snake venom poisoning. Copperhead (Agkistrodon contortrix) snake bites are traditionally not difficult for physicians to manage, because they rarely lead to severe envenomation syndromes. However, because there are occasional reports, sometimes anecdotal, of severe reactions, most of the same treatment rules that are applied to more potentially injurious bites, such as those from rattlesnakes, are applied to copperhead snake bite treatment.
The American College of Emergency Physicians held a Research Forum in association with its Annual Scientific Meeting in Denver, Colorado in October, 2012. One of the presentations was entitled “The Utility of Serial Coagulation Profiles in Management of Agkistrodon Contortrix Envenomation.” RC Bowers and colleagues noted that coagulation (blood clotting) studies are commonly performed at regular intervals for victims of copperhead snake bites, to detect a worsening envenomation syndrome and an anticipation of difficulty with blood clotting, which would lead to undesirable bleeding.
These investigators used a single hospital experience from an emergency department that sees nearly all snake envenomations in eastern and central Kentucky. They looked at the copperhead snake bite experience over three years, which included 31 incidents. Of these episodes, 9 patients were felt to have suffered a mild envenomation, 17 a moderate envenomation, and 5 a severe envenomation. All of the patients had an initial blood coagulation evaluation, and 24 of these were normal initially. Of the 7 patients with an initial abnormal blood coagulation evaluation, repeat testing showed reversion to normal in 5 persons. The other 2 were felt to not be sufficiently abnormal to require additional repeat testing. 27 of the 31 initial patients received antivenom; this group included all of the persons with the initially abnormal coagulation evaluation.
Treating 27 of 31 patients with antivenom for copperhead snakebite seems aggressive, but without more details about the specific clinical presentations, I withhold further comment about that aspect of the report. It would be interesting to see how the envenomations were graded into “mild,” “moderate,” and “severe” categories – was this purely objective or was there subjectivity to it? It would seem that it might be reasonable to withhold additional coagulation testing for persons who initially have normal values and appear to be improving over time, with or without antivenom therapy. However, before I definitively reach that conclusion, I would like to know more of the details of this particular study.
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