Medicine for the Outdoors
Medicine for the Outdoors

Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.

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Recombinant Factor VIIa for Rattlesnake Envenomation

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In a recent issue of Wilderness & Environmental Medicine (Volume 20, Number 2, 2009), Anne-Michelle Ruha and Steven Curry have written an article entitled “Recombinant Factor VIIa for Treatment of Gastrointestinal Hemorrhage Following Rattlesnake Envenomation.” This is a “case report,” meaning that this is a description of a particular medical event, rather than a study. To open the piece, the authors observe that North American rattlesnakes possess venom with properties that can cause severe physiological effects, such as low platelet count and on occasion bleeding. In this report, we learn about a 44 year old man who was bitten on the index finger by an unidentified (unknown for this case) species of rattlesnake. The victim developed massive gastrointestinal bleeding that was treated eventually with a product known as recombinant factor VIIa. His initial clinical presentation included an altered level of consciousness, profoundly low blood pressure (shock), sweating, and vomiting of bright red blood.

The victim was treated with standard aggressive therapy for a rattlesnake bite, which included intravenous fluid replacement and administration of blood and antivenom. However, he continued to bleed, so was administered recombinant factor VII, which is a therapy that has only relatively recently become available to physicians. When the victim had his gastrointestinal tract observed by direct endoscopy, he was seen to have a small tear that accounted for the bleeding. Sadly, the patient grew increasingly ill for a variety of reasons, including kidney failure and overwhelming systemic infection, and died on hospital day 5.

The effects of a venomous snakebite can range from a “dry bite,” in which no envenomation is deemed to have occurred, and for which no particular intervention is necessary, to profound physiological derangement, in which the victim may suffer multi-organ system failure. The important new observation in this case report is the use of recombinant factor VII to treat the bleeding. This product is felt to act directly at the site of tissue injury by a variety of beneficial effects, including generation of blood clotting and activation of specific clotting components (such as platelets). This was a very complicated case, with multiple factors that contributed to the outcome. While it is impossible to attribute the cessation of bleeding entirely to the administration of recombinant factor VII, the timing of the bleeding suggests that it may have had a markedly positive effect. This will bear observation in the future as other clinicians undoubtedly gain experience with this product.

image courtesy of www.EMCrit.org

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Dr. Paul S. Auerbach is the world’s leading authority on wilderness medicine.

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