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Crotalid Envenomation – Spoon-Feed Version

April 7, 2021

Written by Kevin Stoffer

Spoon Feed
This literature review of crotalid envenomation answers 8 clinical questions for ED docs.



Why does this matter?
Crotalid envenomations account for about 10,000 ED visits per year, and we own the golden hour of treatment. CroFab improves limb disability and PRN dosing can lead to decreased hospital stay.

No snakes in these boots
The authors compiled 177 papers in an attempt to answer 8 clinical questions regarding crotalid envenomation.  Filtration of the papers through peer reviewed scoring criteria dwindled the field to 33, with many randomized-controlled, prospective, and retrospective trials filling the cohort.

Here’s the summary:

  1. How should patients with potential crotalid envenomation be assessed?

    • Own the ABCs

    • Extremity swelling and monitoring (take pictures)

    • Labs – CBC (thrombocytopenia/anemia), BMP (potassium/renal function), PT/fibrinogen (coagulopathy) and CK (rhabdomyolysis)

  2. What are the initial steps?

    • Pain control

    • Elevate extremity, monitor the extremity on regular intervals

    • Do not use tourniquets, local debridement, or cautery

    • Contact toxicology/poison control early

  3. Indications for antivenom?

    • Swelling extending beyond 1 major joint, significant necrosis as judged by clinician

    • PT >15, fibrinogen <150, platelets <150

    • Systemic toxicity – such as airway swelling, hypotension, neurological symptoms

  4. Dosing of Antivenom

    • CroFab is dosed in vials

    • 1st dose: 4-6 vials, repeat dosing as needed, maintenance dosing with 2-4 vials

    • Monitor for anaphylaxis

    • Same dosing in pediatric cases

    • Anavip is a formulation of antivenom but only covers rattlesnake envenomation that is now approved for all North American pit viper envenomations.
      (Correction on 4/7/2021: Anavip has recently been FDA approved for this broader indication. Thanks to the toxicologists who caught this error! Please see the comments.)

  5. Copperhead envenomations?

    • These should be managed the same as other crotalid envenomation

  6. Where should they be admitted?

    • Most can go to a medical floor

    • ICU is for neurovascular checks or severe systemic toxicity

  7. Antibiotics?

    • No antibiotics unless there is clinical suspicion of infection

  8. Indications for surgical consultation in the ED?

    • Rising compartment pressures despite appropriate antivenom treatment

    • Blebs and blisters are to be left intact

Source
Spencer Greene et al. How Should Native Crotalid Envenomation Be Managed in the Emergency Department? J Emerg Med. 2021 Feb 20;S0736-4679(21)00029-9. doi: 10.1016/j.jemermed.2021.01.020. Online ahead of print.

Editor’s note: Hi Spencer! ~Clay

3 thoughts on “Crotalid Envenomation – Spoon-Feed Version

  • Great article and post. One clarification to your summary: Anavip is FDA approved for all North American pit viper envenomation (not just rattlesnakes anymore–breaking news). Both antivenom options are safe and effective! Thanks for all the work you do.

  • As Dr. Watkins mentioned, Anavip is now FDA approved for the treatment of all North American pit vipers not only rattlesnakes. This update occurred within the last months. That means Anavip is now also approved for the treatment of copperhead and cottonmouths.

    Of note for the readers, there is an error in the citations that is currently in the process of being corrected. During the publishing process the third citation was accidentally omitted and all citations from 3-29 were shifted up one. If you have questions or concerns please read out to me, the corresponding author. Hopefully this will be corrected soon.

    Thank you for featuring this article.

    Garry Winkler MD

    • Many thanks to Drs. Watkins, Greene, and Winkler for catching this error. The post above has been corrected. This is the power of the #FOAMed movement – real-time review by expert peers. Thanks again to all three of you!

What are your thoughts?