Case Presentation by Dr. Ryan Doss
The following patient presents to your emergency department complaining of pain in his left hand radiating up his left arm after messing around with a friend’s pet snake and getting bitten. He does not know the species of snake. The bite occurred approximately 6 hours ago. (After contacting the friend in question, he denies knowledge of the species of snake as well, stating that he purchased it from a charming stranger 1 week ago who has since left town. In addition, he spent the last several hours destroying the snake by means of blade and fire in retaliation and is unable to recall any patterns or really even any overall general color of the snake. In addition, everybody involved in this story is super drunk. Probably even the snake was.)
You decide to discard the issue of speciation.
The patient is rating his pain as 9/10 and is also reporting a sensation of difficulty breathing and pleuritic discomfort in the left side of his chest. He denies any past medical history, allergies, or previous exposure to snake venom or antivenom.
1) Initial treatment, select as many as appropriate (there are 5 correct answers):
A. ETOH level, TCU, sobriety, firm talking to
B. Proximal limb tourniquet
C. Generate a tincture composed of monkey ladder, cat’s claw, wild gri gri root, and mashed Battus polydamas caterpillars aged in alcohol for 4-6 weeks, then apply to the wound and/or/especially the GI tract
E. Floor Admission
F. 4 vials of FabAV antivenom
G. ICU admission
H. Local suction. Mechanism: Dealer’s Choice.
I. ED amputation
J. Elevate and immobilize the limb
L. Tetanus booster
M. Get a non-venomous creature to bite the patient on the opposite arm and wait for the venom and non-venom to duke it out near the patient’s heart? I just thought of this one
N. Immediate discharge. D/C Instructions: New Pregnancy. He’s not going to read it anyway.
2) 30 minutes after initiating the non-crazy treatments above, the patient develops a fever, generalized urticarial rash, and begins complaining of pain in his knees and wrists. You administer prednisone to treat his serum sickness (I’m not going to waste a question on this, plebs). He is one of the approximately 5% of patients who are unlucky enough to develop serum sickness from the modern FabAV – a much more rare occurrence than with the previous horse serum-based antivenoms. He improves and is granted admission to the [ICU/Floor/TCU/His mom’s house] depending on your answers to the previous question. 4 hours later, the [ICU fellow/floor grunt/Hamidou/patient’s mom] calls you stating that the patient has begun bleeding out of orifices that rarely, if ever, express blood.
Good God, what have you done?
A. The serum sickness has resulted in an autoimmune thrombocytopenia, give more steroids
B. He’s developed sepsis and DIC from a localized wound infection, give broad spectrum antibiotics and for pity’s sake use the sepsis order set
C. Millennia of evolution have resulted in venom components which are highly potent activators of coagulation factors as well as fibrinolytics, causing syndromes similar to DIC; administer blood products and continue scheduled FabAV dosing
D. Did you ever see that movie Outbreak with Captain Hook? Shut down the circulation systems, hijack a helicopter, and whatever you do don’t take off your spacesuit helmet thing even if you have to puke into it.
3) Oh man are you guys getting sick of this yet? Because I’m just getting warmed up. Astutely realizing that FabAV is formulated specifically for North American venomous snakes and, for all you know, this patient’s friend purchased an Asian snake from Beelzebub over there (get it? Charming, itinerant, deals in snakes) and, furthermore, resigning yourself to the fact that your patient is getting worse instead of better, you begin to worry. Or continue to worry. (Also, forget that we admitted the patient previously…there’s no beds or something).
What’s the next step?
A. Surgical consultation. Debridement of the local wound and close monitoring for compartment syndrome may be the difference between limb and not-limb.
B. Poison control. Even without speciation, polyvalent antivenoms (meaning in this context created from multiple species) exist for the most popular Asian or African venomous snakes that can be used in a last-ditch effort.
C. Family conference. Venomous injuries, especially those involving neurotoxin, can progress rapidly and unpredictably, resulting in respiratory arrest, coma, and death.
D. All of those sound pretty good.
Answers and Discussion:
1) Answers: D, F, G, J, L
The mainstays of treatment are antivenom, admission to the ICU for close monitoring, elevation and immobilization of the affected limb, and a tetanus booster. Empiric antibiotics are also recommended and are standard of care, but there is little data to support their use.
Tourniquets and suction (especially with an incision made at the bite site) have fallen out of favor. They do not appear to be effective and are potentially harmful.
Steroids have been shown to be of no benefit. In the real world they are sometimes used for severe cases in a practice I have just decided to call “kitchen sink”-ing. Probably won’t help, though.
The tincture described in answer C is really a collage of various real-life local treatments (from random localities), some of which may be somewhat effective (but nowhere near as effective as antivenom). Tobacco is another popular option. However, the answer is impractical unless you have a tincture prepared ahead of time.
Answer M awaits randomized controlled trials.
2) Answer: C
Much of the hypotheses regarding the evolution of venom are speculative. This is because being an evolutionary biologist is the easiest job in the world and you can basically make stuff up. (Semi-aquatic human ancestors, humbug). However, based on the anatomical structures involved, it can be assumed that the evolutionary progenitors of modern venom were digestive proteins and enzymes – a sort of pre-digestion. Then, when you managed to catch up with your meal, you could finish the job internally. However, some prey animals are very quick. So an evolutionary arms race resulted in chemicals that had the effect of immobilizing the prey in various ways. One of these ways is by breaking down all the various cell walls and basement membranes that interfere with the spread of your venom. This has the added benefit of turning a springy muscular limb into a “I ran out of my Lasix one month ago” limb, which is less effective at propelling your lunch away from you. Another method is to turn your prey into a giant blood clot or cause them to leak all their oxygen- and nutrient-carrying substrate out their eyeballs. Or BOTH, or all of the above plus paralysis via neurotoxin. The treatment is to stay the antivenom course and to replace what’s being used up (with blood, platelet, and FFP transfusions). If your patient is unlucky enough to have been injected with neurotoxin, the treatment is supportive (intubation and sedation).
3) Answer: D
There’s got to be at least one “all of the above.” Probably the most helpful thing you can do in this case is contact poison control. If you had a picture or description of the snake to begin with, this should have been one of the things you did right away. In this case, without speciation, you can describe to them the symptoms and effects of the venom at least. They have access to the local zoo’s stores of antivenom which may include polyvalent options as described above. It’s worth a shot.
Tissue necrosis necessitating debridement may be a direct result of the venom or a secondary effect of compartment syndrome. See below for some pictures of a Lao patient with untreated tissue necrosis of the leg after a snake bite.
As an aside, if you have a patient who comes in with a wild snakebite in the United States the most likely offenders would be coral snakes or pit vipers (rattlesnakes, massasauga, copperheads, or water moccasins). For pit vipers, think of symptoms similar to the patient described above. These include local tissue damage, progressive worsening edema, nausea, vomiting, etc. Treatment is essentially as described above. Administer FabAV if the edema and pain are moderate to severe, and provide supportive care. Coral snakes are less predictable. Whereas a potential victim of a pit viper bite should be treated with antivenom based on the severity of symptoms and edema, ANY patient with a confirmed coral snake bite should be given coral snake-specific Antivenin. Coral snakes kill primarily with neurotoxins, and the effects of these toxins are difficult to predict and somewhat variable in their time of onset. They may be delayed up to 12 hours and the patient may require prolonged ventilatory support. Pit viper bites should be observed for 8 hours, potentially in the ED. ALL coral snake bites should be admitted, potentially to the ICU. You will want to closely monitor coagulation profiles, basic labs, and various measures of pulmonary function (pulse ox, peak flow, respiratory status, chest x-rays) for either type of snake bite throughout their stay.
Finally, here are a picture of a real patient in Laos with a snake envenomation who ended up being discharged home due to lack of funds for transfer to a tertiary care facility. He came back after watching his leg decay for one week. The medical system here is (obviously) quite different than in the United States, and the framework is simply too rickety to support socialistic excesses such as EMTALA. Here, if a patient or patient’s family cannot pay up front for a treatment, transfer, or sterile glove, the patient is denied treatment or discharged. Patients in Detroit also present with advanced pathology secondary to lack of access to primary care, but that’s a bit of a different problem than being sent home to watch your leg fall off because of a lack of Kip. Perspective!
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