Snake Envenomation

Basics

Pit viper venom:
- Mixture of proteolytic enzymes and thrombin-like esterases:
  - Enzymes cause local muscle and subcutaneous tissue necrosis
  - Esterases have defibrinating anticoagulant effect, leading to venom-induced consumption coagulopathy (VICC) in severe envenomations
Bite location:
- Extremity bites most common
- Head, neck, or trunk bites more severe than bite on extremities
Severe envenomation:
- Direct bite into artery or vein
- Neurotoxic envenomations
Bite mark significance:
- Pit viper bite: Classically includes 1 or 2 puncture marks
- Nonvenomous snakes and elapids: Horseshoe-shaped row of multiple teeth marks
25% of all pit viper bites are dry and do not result in envenomation

Venomous Snakes Indigenous to the U.S.

Pit vipers (Crotalinae):
- Account for 95% of all envenomations
- Rattlesnakes, cottonmouths, and copperheads
Coral snakes (Elapidae):
- Neurotoxic
- Western coral snakes, found in Arizona and New Mexico
- More venomous eastern coral snakes, found in Carolinas and Gulf states

International Exotic Venomous Snakes
Occur in zoos or in owners of exotic snakes
Pediatric Considerations

30% of all snakebites involve patients younger than 20 yr. 12% of all snakebites are 9 yr or younger
Because of their low body weight, smaller children and infants are more vulnerable to severe envenomation with systemic symptoms

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