If I Had To, How Would I Use Anti-Venom?

Patient Presentation
A 7-year-old male was playing with a large box that had been in the yard undisturbed for several days.
He was kicking and moving the box when he noticed a small snake at the opening. He ran away and called his parents.
His father, using gloves, moved the box to the edge of the yard and when the box tipped over several small snakes and a large snake with a copper-colored body and triangular shaped head emerged and slithered into a marshy area nearby.
The father who was a general pediatrician realized that he and his son had been very lucky in not being bitten, probably by a copperhead. Later he realized that he did not know how to use snake anti-venom and decided to do a PUBMED and general Internet search. He found several references to answer his question.

Discussion
In the United States there were 3264 snake bites reported to the American Association of Poison Control Centers in 2007.
Bites and envenomations were the 13th most common substances involved in human exposures as reported by the same group.
There are basically two types of venomous snakes in the U.S.:

• Family – Crotalidae
  • Pit Vipers – copperheads, rattlesnake, cottonmouth, sidewinder
  • About 98-99% of all envenomations
  • Occur more in warmer months but can occur at any time
  • Bite reactions:
    • Extensive local reaction with severe pain and extensive regional swelling that can occur in as little as 10-30 minutes.
    • Coagulation disorders may follow such as epistaxis, purpura, hemolysis or disseminated intravascular coagulation occurring in 30 minutes-48 hours.
    • Shock can also be seen at the same time as the coagulation disorders.
    • Necrosis occurs after 6 hours and needs appropriate wound care.
• Family Elapidae
  • Coral snakes
  • Along with imported venomous snakes = ~1-2% of all envenomations
  • Bite reactions:
    • Neurological syndromes move the patient toward respiratory paralysis and coma are seen.
    • Hypotension, myosis, hypersalivation, increased sweating, dysphagia and dyspnea can be seen along with paraesthesia and paresia. This can occur in the first 10-30 minutes.
    • Later, 30 minutes-5 hours, patients will have ptosis, trismus, respiratory paralysis and shock.

Learning Point
About 20-50% of snake bites have no envenomation. If an envenomation occurs, the severity depends on many factors, especially snake factors such as the quantity of venom injected. The bite site is important (head and neck are more dangerous), as are the size and weight of the individual with children being more seriously affected. Fang marks may not be seen, or there may be fang marks, scratch marks, vesicles or hemorrhagic blebs seen. Measuring the distance between the fang marks can give a general idea of the size of the snake.

Initial treatment is rest, immobilization with the affected part below the heart and transportation to a hospital. If no envenomation appears to have occurred then patients are usually watched for 6-12 hours. Laboratory testing especially for respiratory status (blood gas) and coagulations disorders is necessary and needs to be re-evaluated at regular intervals. Anti-venom is the treatment for snake bites where envenomation has occurred. There are two types of antivenom: horse-derived and ovine-derived. Horse antivenom can cause allergic reactions including anaphylaxis. Ovine-derived appears to have fewer side effects. One study of ovine antivenom used for rattlesnake evenomations in children showed it was safe and seemed to be effective. Anti-venom is NOT give on a weight basis but is given on a vial basis. Children may require more anti-venom than a similar bite in an adult. Poison control experts can provide guidance for health care providers treating evenomations. Poison control centers are available nationally by calling toll free at 1-800-222-1222.

Questions for Further Discussion
1. How do you treat scorpion bites?
2. What spiders are commonly poisonous and how are they treated?

Related Cases

Disease: Animal Bites

Symptom/Presentation: Health Maintenance and Disease Prevention

Specialty: Critical Care | Emergency Medicine | Pharmacology / Toxicology | Travel Medicine

Age: School Ager

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Animal Bites

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

Medicine Sans Frontieres. Snake Bites. Clinical Guidelines Diagnosis and Treatment Manual. 2007:272-274.

Bronstein, AC, Spyker, DA, Cantilena JR, LR, Green, JL, Rumack, BH. and Heard, SE.2007 Annual Report of the American Association of Poison Control Centers’ National Poison Data System (NPDS): 25th
Annual Report,Clinical Toxicology, 2008;46:10,927 — 1057.

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