Snakebite Management (in hospital) – Pit Vipers

Please allow me to introduce myself. I am a medical toxicologist and emergency physician at Baylor College of Medicine in Houston, Texas. I have treated 600+ snakebites and direct one of the busiest snakebite services in the U.S.

I also love snakes and consider myself a member of the herpetology community. And I want to help prevent any bad outcomes (for both humans and snakes) if a snake-human interaction goes awry.

I have seen A LOT of bad advice regarding snakebite management in this and other groups, and I’d like to set the record straight. These are the recommendations for emergency department and inpatient treatment. I have a different post dealing with pre-hospital management.

If you end up in the hospital with a snakebite, certain things will (or at least should) happen:

*** Note – this applies to pit viper (crotalid) bites. For coral snakes, see this post.

Any airway or circulatory compromise will be rectified immediately.

Analgesia should be provided (NSAIDs such as ibuprofen (Motrin, Advil), naproxen (Naprosyn, Aleve) and Toradol (Ketorolac) should be avoided because of the potential hematologic effects. Parenteral opioids are often necessary. I try to avoid morphine because of its greater effect on histamine, but that’s a subtle point.

The affected extremity should be ELEVATED if it’s a pit viper bite. For coral snake bites, below heart level makes sense, but I just go with whatever is most comfortable for the patient.

Hopefully the physician is able to recognize a pit viper bite. If he or she cannot, you may want to consider transfer to a facility with a snakebite expert. Or you can request that the doctor calls the regional poison center (1-800-222-1222) for consultation with a medical toxicologist.

Related:  Coralsnake Envenomations

Most (80 – 85%) pit viper bites will result in envenomation. And most envenomations ought to be treated with antivenom, which can minimize the amount of local tissue damage, reverse hematotoxicity and treat systemic toxicity. Currently (June 2017) the only available and FDA-approved antivenom for North American pit vipers is CroFab, which is ovine (sheep)-derived.

Too many physicians do not treat with antivenom when they ought to. Some do not treat because they don’t understand the indications. Indications for AV include:

  • Progressive local injury. Most experts consider swelling that crosses any major joint (e.g. ankle, wrist) sufficient justification to treat;
  • Systemic toxicity, such as hypotension, airway swelling;
  • Hematotoxicity, including lab abnormalities;
  • Another reason that some doctors do not treat with AV – fear of potential adverse outcomes. In reality, AV is very safe, In a meta-analysis from 2012, there was an 8% incidence of acute hypersensitivity reactions.

More recently, data from the North American Snakebite Registry suggest an incidence of ~ 2.7% .

In the study comparing CroFab to Anavip, the acute adverse incidence was 2.75%.

Incidentally, CroFab can be given safely to a patient more than once in his or her lifetime. I have treated almost two dozen patients multiple times. People who play with snakes sometimes get bitten by snakes….

Many physicians have withheld AV in the setting of copperhead bites, both because they believe that copperhead bites are no big deal and because, for a long time, there was no proof that CroFab improved outcomes (they were not included in the original CroFab studies). Well, I treat ~ 75% copperhead bites and I assure you they absolutely can be serious, and I can also say that our recently-published study proves that even mild copperhead bites improve faster and get off of opioids much sooner if they’re treated. I suspect the difference is even more profound for moderate and severe bites.

Related:  The Seriousness of a Copperhead Envenomation

Finally, cost of AV is a reason some doctors don’t use it. AV can be expensive, though insurance covers some amount. But a permanent disability can also be expensive. It’s better to get treated successfully and figure out how to pay for the hospitalization than not get treated and be unable to work.

There are some interventions that are unnecessary and possibly dangerous.

In general, snakebites are not associated with infection. In 1997, Kerrigan et al. showed that empiric antibiotics do not improve outcomes and in 2015 my colleagues and I proved that infection is exceptionally uncommon in snakebite. So no need for empiric antibiotics.

Similarly, snakebites are a MEDICAL condition. Surgery is pretty much never necessary acutely (though occasionally a finger amputation may be needed if there is necrosis, but that’s down the road). Prophylactic fasciotomies worsen outcomes. Compartment pressures are not usually elevated because the venom gets deposited above the fascia. There is significant soft tissue swelling, but rarely elevated intra-compartmental pressures. But the most important reason not to do fasciotomies is that elevated pressures are a SIGN of significant envenomation but NOT THE CAUSE of bad outcomes. Fasciotomy increases myonecrosis and, in animal studies, mortality. So if a surgeon is consulted early in your care, consider getting transferred elsewhere….

Other things to know:

  • Steroids are not indicated in snakebites unless there is an allergic phenomenon. They don’t help and could predispose to both infection and poor wound-healing.
  • DO NOT cut and suck. All this does is make a wound worse and potentially introduces bacteria into the wound
  • DO NOT apply a tourniquet. There is no benefit in cutting off an extremity’s arterial blood supply unless the patient is bleeding to death.
  • DO NOT apply any sort of constriction band or pressure immobilization for pit vipers. For the same reason that we do not place the affected extremity below heart level. The American College of Medical Toxicology has a position statement on this.
  • Pressure immobilization IS reasonable for coral snake bites.
  • DO NOT use electrical shock treatment. It does not “neutralize the venom” or whatever nonsense advocates claim. But it is a good way to cause permanent injury.
  • DO NOT apply heat.
  • DO NOT apply PROLONGED icepacks. A few minutes at a time is okay (say, 5 minutes on, 10 minutes off) but prolonged cryotherapy is bad for the tissue.
  • DO NOT use one of those commercially-available suctions devices. They don’t remove venom. They just suck. See the best-titled editorial ever here: http://www.doctorross.co.za/wp-content/uploads/2009/01/bush-sp-snakebite-suction-devices-suck-emerg-med-clin-n-am.pdf
  • A great reference is the unified treatment algorithm for management of crotaline envenomations.
Related:  Debunking the Myth that Antivenom More Dangerous Than a Snakebite

Related:

Pre-hospital Snakebite Treatment

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About

Spencer Greene, MD, MS, FACEP, FACMT is the Director of Medical Toxicology and an Assistant Professor in the Henry J.N. Taub Department of Emergency Medicine at Baylor College of Medicine. He directs the only medical toxicology service in Houston. Clinical interests include salicylates, anticonvulsant toxicity, physostigmine, alcohol withdrawal, and envenomations, and he consults on more than 100 bites and stings annually, including snakebites, spider bites, asp envenomations, and jellyfish stings. He serves as a consulting toxicologist for the Southeast Texas Poison Center and has directed the annual Houston Venom Conference since its creation in 2013. He was also the course director for the American College of Medical Toxicology's Natural Toxins Academy.

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