Snake Bite Management
Please allow me to introduce myself. I’m a clinical professor at the University of Houston College of medicine. I have also worked as 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 and I’d like to set the record straight. These are the recommendations for pre-hospital treatment. I will have a different post dealing with hospital management.
If you get bitten by a snake you suspect is (or may be) venomous:
1. Get away from the snake. No need to hurt the snake just because you’re angry, and you don’t want to incur additional injury.
2. If you (or someone else) can safely and quickly get a picture of the snake, great, but don’t waste time or risk a second envenomation. Ultimately, pit viper (rattlesnakes, copperheads, cotton- mouths/water moccasins) envenomations are diagnosed clinically. As are coral snake bites, but most people can identify those. Just pray you have a doctor who knows what he or she is doing..
3. Remove constrictive clothing and jewelry.
4. Position the affected extremity appropriately. DO NOT PLACE BELOW HEART LEVEL. Almost all pit viper bites cause local tissue injury, and placing the affected extremity below heart level will cause the venom to collect in the extremity and will increase the hydrostatic pressures in the extremity. This will increase the potential damage to lymphatic vessels and increase the likelihood of some degree of permanent injury, such as post-exertional swelling. Once in the hospital, the affected extremity should also be elevated. This is emphasized in the unified treatment algorithm. (which can be found here, bmcemergmed.biomedcentral.com)
5. Get to an appropriate hospital. If you are having life-threatening signs and symptoms (e.g. airway issues, low blood pressure) get to the closest hospital for stabilization. They can then transfer you if needed to an expert. Otherwise, proceed directly to a hospital with a snakebite expert. If you interact with snakes a lot or are outside in snake-endemic areas, you should investigate your regional hospitals to locate one or more specialists. I can help you with this. It’s a pretty small community. Join the National Snakebite Support group on Facebook to learn more.
6. Avoid dangerous and/or stupid interventions:
• 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 here; www.ncbi. nlm.nih.gov/pmc/articles/PMC3550191/
• 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, five 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.
• 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.
7. Do not bring the snake to the hospital. A dead snake can still envenomate you, and I hate when people kill snakes. And as much as I like snakes, I do acknowledge it becomes a logistical difficulty when someone brings a live snake to the ED. And, as I said before, we don’t need to see the snake to provide appropriate treatment.
Even if you are an hour or more from a hospital, these are the steps you should take. Treatment is MOST effective in the first few hours, but may still be helpful after a delay of one or more days.
If you end up in the hospital with a snakebite, certain things will (or at least should) happen:
*** Note – this applies only to pit viper (crotalid) bites..
• 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.
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.
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. Curthere are two FDA approved antivenoms for North American crotalid envenomations.
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.
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.