Predicting Severe Pit Viper Envenomation

Snakebite severity ranges from “dry bites” to mild symptoms to life-threatening severe envenomations; patients with severe envenomation can present initially with mild symptoms. These authors conducted a systematic review to identify clinical factors that predict severe envenomation from Western Hemisphere pit viper bites (pit vipers are responsible for 98% of U.S. snakebites).

The review identified 17 studies involving 5915 patients; the authors categorized severe outcomes as systemic toxicity, tissue necrosis, and hematologic toxicity. Pooled prevalence of severe systemic toxicity was 14%, of tissue necrosis was 14%, and of severe hematologic toxicity was 18%. Factors associated with increased likelihood of severe systemic toxicity were ti…