Part 1: Emergency Department Management
Spencer Greene, MD, MS, FACEP, FACMT, FAACT, FAAEM 30 July 2021
Hopefully you’ve arrived at a hospital where the physicians have expertise in managing crotaline snakebites. Many places do not. Do your homework before you’re a patient.
What are the steps that should be taken when you arrive? I call them the four “A”s:
In medicine, we often use ABCDE to describe the initial steps in resuscitation. A = airway. We have to secure the airway, which is fortunately only compromised in a small percentage of snake envenomations. B = breathing. We must maintain oxygenation and ventilation. C = circulation. We must ensure adequate tissue perfusion. In trauma, D = disability. However, in snakebite management, D = Dilaudid™, to remind people of the importance of analgesia. You do not actually have to use Dilaudid (hydromorphone) – any parenteral opioid is fine – but if we use one with a different brand name, my mnemonic doesn't work! Finally, in snakebite management, E = elevation. As I mentioned in the prehospital management blog, elevating the affected limb reduces pain and minimizes tissue injury. It is one of the first things recommended in the unified treatment algorithm and the American Academy of emergency medicine snakebite guidelines. I cannot overemphasize how much good elevation improves the local tissue findings following snake bite.
Next is ASSESSMENT. Hopefully by now we’ve identified any systemic toxicity. There are certain laboratory tests I recommend checking: CBC, prothrombin time, and fibrinogen to assess for hematologic toxicity. I also check CK and BMP. We need to make serial assessments of the affected limb. While it is elevated appropriately, mark the most proximal area of tenderness and swelling. Reassess every 15 minutes or so and note the magnitude and rate of progression.
One of the most common mistakes when it comes to managing snakebites is observing the patient for an insufficient amount of time. Snakebites are dynamic, and what looks insignificant at first may become much more serious over several hours. If there are no signs or symptoms, observation is still warranted for at least 8 hours. Many “dry bites” are misdiagnosed because they are discharged from the emergency department prematurely. Remember, a dry bite means there are no venom effects, which include swelling, bruising, or significant tenderness. If these are present, it’s not a dry bite, regardless of the laboratory test results.
If there is ANY evidence of envenomation, observation for at least 12 – 24 hours is warranted.
Not every envenomation requires antivenom; minimal envenomations (no systemic or hematologic toxicity, local findings confined to < 5 cm from the bite site) can be managed symptomatically. Envenomations that are more than minimal, however, should be treated with antivenom.
ANTIVENOM should be administered for ANY of the following:
Historically, many healthcare professionals have withheld antivenom until the local findings crossed two major joints, e.g., knee or elbow. I have a lower threshold to treat: tender swelling that crosses one major joint. Think of an envenomation like a fire. If you allow it to spread a lot before you treat, you allow more damage to occur. Knock it out sooner and it results in less damage. It also costs less to treat early, because worse envenomations, like worse fires, require more resources (e.g., more vials of antivenom.)
The final step is AVOIDANCE of treatments that are unnecessary and possibly harmful. These include corticosteroids and antihistamines in the absence of allergic phenomena; prophylactic antibiotics, and acute surgical intervention. I will discuss these further in my next blog, which will discuss inpatient management and discharge criteria.
Dr. Greene is a paid consultant for BTG International Inc.
Spencer Greene, MD, MS, FACEP, FACMT, FAACT, FAAEM is a board-certified medical toxicologist and emergency physician. He currently serves as the Director of Toxicology and an attending emergency physician at HCA Houston Healthcare-Kingwood. He is a Clinical Professor at the University of Houston College of Medicine. Dr. Greene is a recognized expert in the management of snake envenomation in the US. He has treated more than 1000 snakebites at the bedside and has authored more than 50 scholarly articles and book chapters. He has also served as the course director for the Houston Venom Conference since 2013.