Snake Envenomations in North America

Posted by: NOLS on 7/1/11 3:02 AM

In North America snake envenomations are generally caused by Crotalids (e.g., pit vipers: rattlesnakes, water moccasons, copperheads) and far less frequently Elapids (coral snakes).

Signs and Symptoms
Pit Viper Bites (Rattlesnakes, Water Moccasins, Copperheads)
• Fang Marks
• Swelling and pain. If absent after 30 minutes envenomation probably did not occur.
• Ecchymosis and bleb formation (over 6-36 hours) and later necrosis
• Weakness, sweating and chills
• Nausea and perhaps vomiting
• Numbness and swollen lymph nodes
Coral Snakes
• Local swelling, nausea, vomiting
• Dizziness, weakness, respiratory difficulty (up to 12 hours after bite)

Treatment Principles
• Scene Safety! Try to identify the snake, but not if it puts anyone at risk.
• Keep yourself and the patient calm.
• Avoid walking.
• Remove constricting clothing and jewelry from the bite site.
• Consider pain medications.
• Monitor for signs of envenomation.
• Splint the extremity. Avoid elevating the injury.
Pit Viper Bites (Rattlesnake)
• Measure and monitor swelling.
Coral Snakes (Elapids)
• A wide elastic bandage (pressure immobilization bandage) wrapped distal to proximal as tight as an ankle wrap.

DO NOT:
• Cut and suck, use a suction device, apply ice.
• Use electricity, a tourniquet or constricting band on pit viper bites.

Prevention
• Know if you are traveling in snake country.
• Don't pick up or corner a snake.
• Avoid blind placement of hands and feet in suspect areas.
• Avoid traveling at night without a light.

Non-North American Snakes
In general treat Elapid bites with a pressure immobilization bandage, and viper bites with immobilization. Evacuate both to hospitals for anti-venom. Washing a wound is not recommended in Australia as it interferes with testing for presence of venom. Research local snakes prior to travel for prevention advice, local treatment protocols and availability of anti-venom.

Evacuation Guidelines Summary
• Evacuate all patients bitten by a snake.
• Rapidly evacuate patients with signs or symptoms of envenomation.

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