About Snake Bites and Snake Bite Management
It is natural to be scared following a snakebite. Take comfort in the fact that most snakebite victims will recover fully if they receive appropriate medical attention. So, what should you do if you or a loved one gets bitten by a snake? If you are 100% certain that the snake is nonvenomous, wash the area with soap and water and stay home. You’ll be fine. Infection following a bite from any snake – venomous or nonvenomous – if exceptionally uncommon, and it is not appropriate to start empiric antibiotics. Similarly, the likelihood of getting tetanus from a snakebite in the Western hemisphere is essentially nil. If your last TDaP was less than 10 years ago, there’s nothing you need to do. If it has been > 10 years, make an appointment for another booster shot. If you’ve never been immunized, start the process. There is no need for tetanus immunoglobulin because snakebites are a low risk for tetanus. If you’re bitten by a venomous snake, or if you don’t know whether a snake is venomous, seek medical attention at a hospital – not urgent care, and not your primary care provider’s office. Do not drive yourself. If you’re not experiencing significant symptoms and someone can get you the hospital, it is reasonable to go in a car. However, if there are worrisome signs or symptoms, or for the long transport time, it makes more sense to call 911, because they can bring medical attention to you. Most of the previously recommended prehospital treatments for snakebites have been proven to be useless at best and dangerous at worst. Do not tie a tourniquet or any sort of constrictive bandage around the affected extremity. These will exacerbate the local damage and, when done incorrectly, will increase systemic toxicity simultaneously. A tourniquet is great when you want to stop life-threatening bleeding, but you don’t want to cut off the arterial blood supply to a bitten extremity. Although lymphatic constriction bands and pressure immobilization don’t cut off the blood supply, they do (theoretically) confine the venom to the affected extremity, which, particularly when combined with the increased swelling, causes increased local tissue injury. Because local injury is seen in > 95% of crotalid envenomations, and for most envenomations that’s the only significant manifestation, we need to avoid this. All of the major toxicology organizations produced a position statement condemning the use of pressure immobilization for native crotalid envenomations. Furthermore, if pressure immobilization is performed incorrectly, it can actually enhance systemic venom absorption while simultaneously causing local injury. And, as you can see in Dr. Norris’ paper, most people perform PI incorrectly:
You can read the pressure immobilization position statement here:
Do not use a venom extraction device. They remove almost no venom following a bite (no more than 2% in one study). Certainly not a clinically significant amount. Furthermore, there is good evidence that they are harmful. They can cause a negative pressure injury and, by preferentially removing interstitial fluid, these extraction devices could theoretically concentrate the venom. These kits are good for one thing: profits for the people who manufacture and sell them. But they are certainly not beneficial to a snakebite victim. Here are some excellent studies that look at the risks and benefits of extraction devices: •
Suction for venomous snakebite: a study of “mock venom” extraction in a human model and Effects of a negative pressure venom extraction device (Extractor) on local tissue injury after artificial rattlesnake envenomation in a porcine model
• This one is the best-titled editorial ever:
Do not pack the affected extremity and ice Do not try to use electrical therapy; this will do nothing for the envenomation. It can cause burns and, occasionally, electrocution. Do not “cut and suck”; this will not remove the venom. It will make the local injury much worse. Instead, do the following: Remove any constrictive clothing and jewelry Elevate the affected extremity for a pit viper bite (you can keep a coral snakebite in whatever position is most comfortable for the patient. Elevation will have no effect on the absorption of venom but will significantly reduce the swelling and associated discomfort of a pit viper bite There is no need to bring the snake with you to the hospital. Bringing a live snake is obviously potentially dangerous to humans as well as the snake. Bringing a dead snake is also dangerous to humans. People forget that dead snakes can envenomate, typically for about 30–45 minutes after the fatal injury, but the record is approximately 8.5 hours. Don’t believe me? Check these out: This guy DIED after getting bitten by a dead prairie rattlesnake:
This guy almost died after getting bitten by a dead rattlesnake:Bodyless rattlesnake bites Texas man after it was decapitated
This guy got envenomated by a dead copperhead:
Clinically Significant Envenomation From Postmortem Copperhead (Agkistrodon contortrix)
Most importantly, and this may blow some people’s minds, we don’t actually need to know what snake is responsible for the bite! All we have to do is determine whether or not it is a pit viper envenomation, and that’s a clinical diagnosis. A physician who is knowledgeable about snakebites can easily distinguish a bite from a crotalid from a bite from a non-venomous snake. And, in regions where this is relevant, it’s also easy to distinguish a coral snake bite from a pit viper bite and from a bite from a non-venomous snake. Once we determine whether or not it’s a pit viper bite, we’re good. Because CroFab is FDA-approved for all North American pit vipers: copperheads, cottonmouths, rattlesnakes. We do not need to know the species in order to treat appropriately. If you can take a picture of the snake quickly and safely, that’s great. Almost everybody has a camera phone, and it’s nice to know the species for epidemiological purposes. However, we definitely don’t want to delay transport or treatment trying to ID the snake. You treat the patient based on the signs and symptoms. Lastly, remember that Benadryl (diphenhydramine) provides no benefit following snakebite. . Benadryl is an antihistamine. Histamine is not a major component of snake venom, so antagonizing the effects of histamine accomplishes nothing. It does not “buy time” or “reduce inflammation” or anything of the sort. All it does is give people a false sense of security and distracts them from the most important thing: getting to the hospital so that someone can determine the need for antivenom, which is the definitive treatment for snake envenomation. The only time Benadryl may be helpful is in the rare case of an allergic reaction to either the venom or the antivenom. And in serious reactions, the drug of choice would be epinephrine, not Benadryl, which helps for hives and itching but not the cardiac or respiratory complications. Please read this excellent article by Dr. Nick Brandehoff:
You can also read the most recent anaphylaxis practice guidelines, which address the lack of utility of antihistamine, here:
National Snakebite Support
Facebook group with the nations leading snake bite professionals ready to answer questions and advise you through your snake bite.
Clinical Practice Statement How Should Native Crotalid Envenomation Be Managed in the Emergency Department?
(9/14/2020)
Chairs: Michael Abraham, MD FAAEM
Grzegorz Waligora, MD FAAEM
Authors: Spencer Greene MD MS FAAEM
David Cheng, MD FAAEM
Reviewers: Al Giwa, MD MBA MBE FAAEM
Lisa Mills, MD FAAEM
Disclosures:
Dr. Greene has disclosed a conflict of interest-served as a speaker for BTG/Boston Scientific.
Drs. Cheng, Giwa and Mills have disclosed no commercial relationships or conflicts of interest.
Statement reviewed and approved by AAEM Board of Directors. (9/14/2020)
CroFab® is the only FDA-approved treatment for all North American pit viper envenomations in adult and pediatric patients. 98% of venomous snakebites in the United States are from the North American pit viper.
Approved in 2000, CroFab® was designed to reduce the high incidence of hypersensitivity that occurred with previous antivenom therapy, and to provide a geographically relevant antivenom. In the years since, CroFab® has become the antivenom that healthcare professionals rely on for the treatment of North American pit viper envenomation.