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Recurrent and persistent coagulopathy following pit viper envenomation
L V Boyer1, S A Seifert, R F Clark
1Department of Pediatrics, University of Arizona Health Sciences Center and Arizona Poison and Drug Information Center, Tucson 85724, USA.
Archives of Internal Medicine
|April 28, 1999
Summary
Coagulation problems can persist for weeks after pit viper snakebites. Close monitoring of patients for up to 14 days post-envenomation is crucial for effective treatment and management of coagulopathy.
Area of Science:
- Toxicology
- Hematology
- Clinical Medicine
Background:
- Crotaline (pit viper) envenomation traditionally considered to cause short-lived coagulation abnormalities.
- Limited laboratory data exists beyond the initial days post-treatment.
- Observed coagulation defects up to 2 weeks post-envenomation during an antivenom trial.
Purpose of the Study:
- To document and characterize recurrent or persistent coagulopathy.
- To assess outcomes in patients envenomed by pit vipers and treated with a Fab antivenom.
Main Methods:
- Prospective, multicenter clinical trial of patients with moderate pit viper envenomation.
- Administration of a Fab-based antivenom (antivenom polyvalent crotalid (ovine) Fab).
- Monitoring of coagulation parameters (platelets, fibrinogen, fibrin split products, PT, PTT) for 2 weeks post-treatment.
Main Results:
- 20 out of 38 patients (53%) exhibited recurrent, persistent, or late coagulopathy (2-14 days post-envenomation).
- Recurrent thrombocytopenia occurred in patients with prior thrombocytopenia.
- Hypofibrinogenemia occurred in patients with prior hypofibrinogenemia or positive fibrin split products.
- No significant spontaneous bleeding observed; one minor bleed post-surgery.
Conclusions:
- Prolonged or recurrent coagulopathy is possible after North American pit viper envenomation.
- Periodic dosing of Fab-based antivenom may be more beneficial than single-bolus administration.
- Close patient monitoring for coagulopathy is recommended for the first 2 weeks post-snakebite.