I was late with the What Would You Do? Wednesday last week, but that’s ok! We’ll manage one way or another. This week, I gave you a video featuring everyone’s favorite outdoor adventurer, Bear Grylls. Like all good bears (Mr. Grylls, if you’re reading, the joke had to be made), Mr. Grylls appears to appreciate free range honey.
Unfortunately, it also appears that he reacts badly to being stung, and swells up impressively after taking one to the forehead. If you haven’t had a chance yet to watch the video, take a few minutes and do it! It’s short!
Some quick facts, courtesy of the Cleveland Clinic. File this under “why is this important to me?”
“Insect sting allergy can develop at any age and usually manifests after several uneventful stings. The incidence of systemic reactions to Hymenoptera venom is approximately 3% in adults. Although children are stung more often than adults, systemic reactions occur in only about 1% of children younger than 17 years, and many of these reactions are relatively mild. Large local reactions to Hymenoptera stings are more common in children, with an estimated incidence of 20% and 10%, respectively, for children and adults. The prevalence of insect sting allergy is twice as high in male as in female patients and may be a result of increased exposure rather than inherent susceptibility. There is no clear association with other allergies, and only 30% of patients with venom allergy are atopic. In addition, insect sting allergy is statistically not more likely to occur in persons with a family history of sting reactions. At least 50 deaths per year occur in the United States from insect sting reactions, and many other sting fatalities may be unrecognized. Approximately one half of deaths occur in victims with no history of a prior sting reaction. Most fatalities (80%) occur in adults older than 40 years, and only 2% occur in persons younger than 20 years.”
So, what are some things that I notice?
- Removing the Stinger: There are various types of stinging Hymenoptera out there; some leave stingers behind after they sting, others do not. These appear to be the former. Currently, best practice suggests that the best way to get an embedded stinger out of the skin is to use a card-like object to scrape the stinger clear. Using tweezers (or, in this case, fingers) may actually squeeze the stinger and force additional venom into the skin. I’m not sure, but I suspect that removing the stinger in the way it was done in the video may have made things worse.
- Venom or Poison? Recall that the difference between poison and venom is that poison is from plants, whereas venom is from animals. Or, as was once said, if you eat something and die, you’ve been poisoned. If something bites you and you die, you’ve been envenomated. This would count as being envenomated.
- Why is this happening? An allergic reaction is an immune response mounted by the body against an irritant, called an antigen. Most typically, allergic reactions are started against foreign proteins, which the body is used to attempting to destroy in an attempt to destroy invading viruses. Venom is basically a massive bolus of foreign protein. According to the Cleveland Clinic:
“Venoms of the flying Hymenoptera are largely aqueous solutions containing proteins, peptides, and vasoactive amines. The toxic properties of the venom are caused by these components collectively, and several of the venom proteins are allergenic.”
- Local Reaction? Systemic Reaction? A little of both? Treating allergic reactions hinges on recognizing if an allergic reaction is staying local (confined to the site of injury), or is becoming systemic (making changes elsewhere in the body). The ultimate in systemic reactions in the anaphylactic reaction resulting in anaphylactic shock. An anaphylactic reaction is an overblown, out of proportion systemic immune response to an antigen, which results in massive vasodilation, drop in blood pressure, angeoedema (swelling of the mouth, tongue, and lips) and laryngoedema (swelling of the throat/airway). Looking at Bear, he appears to be having a pretty big local/semi-local reaction (which some sources I read call a large local reaction), but he doesn’t appear to be having difficulty breathing, breathing with obvious stridor (a whistling sounds caused by constricted airways/swelling), or having symptoms of poor perfusion and hypotension. That said, it’s a short video clip and I’m not able to take vital signs.
- Location, location, location: Bear is in a pretty remote area. This will cause planning an evacuation difficult, if anything progresses.
If you want a more in-depth explanation of the physiology behind the anaphylactic reaction, I encourage you to watch this video. One of the instructors at Landmark Learning turned me on to the Osmosis YouTube channel (thanks, Scott!)
So, what are we going to do for Bear? We’ve got to save the face; he’s a TV personality, after all. Also, I had several suggestions that I have Bear drink his own urine, as he has several times in other episodes. I’m all for it, but only if his urine has vaso-dialatory or histamine blocking properties (I joke…).
- Plan for Evacuation Early and Often: This is a leadership thing. As you move through the backcountry, planning for the worst should always be somewhere in the back of your mind. Hopefully, I’d have done some background planning for evacuation before Bear ever went for the honey. Now is the time to bring that back of the mind planning to the front of your mind. Now, I’m not saying I’d evacuate immediately; Bear appears to be dealing with his reaction well. I’m not seeing any airway involvement at this point, but now would be a good time to find out if he has had allergic reactions like this in the past, and to find out what the usual course is. If he says he has had airway issues in the past following being stung, we’re leaving now.
- Down with Histamines! Histamines are chemical messengers. The body releases them as part of the immune response, and they cause increased vascular permeability as part of the inflammation response. This allows white blood cells to move more easily out of the capillaries so they can fight invaders. However, this also allows fluid to move out of the capillaries. Additionally, sometimes this swelling goes out of control, and we see this in the video. So, let’s stop the histamine response! Diphenhydramine, also called Benadryl, is a histamine blocker. At the WFR/WEMT level, we can give diphenhydramine by mouth, at a suggested dosage of 25-50 mg at intervals of 2-6 hours depending on severity of reaction. At the ALS level, we can also give diphenhydramine IV or IM, at 25-50 mg. Max dose per day is 300 mg. My personal suggestion is to give diphenhydramine early, before airway the airway is compromised and the patient can still swallow. This way, if you do end up giving epinephrine (more about this in a moment), the diphenhydramine will be kicking in as the epi wears off. Additionally, the patient may gain relief in less serious reactions without airway compromise.
- Our previous treatments have been focused on local reactions. We kick into high gear the moment we start seeing symptoms of a systemic allergic reaction. This is the critical decision we have to make. At that point, we switch from attempting to treat in the field to treating/field stabilization while evacuating.
- Bring on the Big Guns: If the patient presents with airway compromise due to anaphylaxis, the indicated treatment is epinephrine, no ifs, ands, or buts. The classic way this is administered is through a large muscle such as the buttocks using an auto-injector like the Epipen. Note that epinephrine for allergic reactions is delivered either subcutaneously (under the skin) or IM (through a muscle); paramedics, unfortunately, are famous for getting confused and giving cardiac doses of epinephrine IV instead of IM; this has caused serious harm to patients. The dose is 0.3 mg IM, usually 2-3 times at 5 minute intervals.
- A suggestion regarding when to give epinephrine. I wait to give epinephrine until I see signs of airway compromise, such as angeoedema or laryngoedema. While many patients are prescribed epinephrine for serious reactions, not all will always develop airway compromise. My thought is to wait until I see actual airway problems so I don’t give my (probably limited) epinephrine away before its truly needed. In this case, while I agree that Bear’s facial swelling is impressive, I would not say he needs epinephrine right now. That said, I’ll probably be following him around, armed with my epinephrine, until that swelling goes down.
- Treat the Shock: If Bear does become anaphylactic, he’ll also begin showing symptoms of shock. This is due to the histamine response causing leaky blood vessels, but also because of vasodilation. We always remember to use the epinephrine; we tend to overlook trying to fix the hypotension/hypoperfusion. If you’re at the WFR/WEMT level, maybe we’ll try oral rehydration as long as the airway is patent. If you’re at the ALS level, an IV with a fluid bolus of 20-30 mL/kg is an acceptable treatment. If the pressure doesn’t improve, repeat the bolus! We’re looking for a MAP (mean arterial pressure) of at least 65, as this is the minimum pressure needed to perfuse the kidneys.
- Other medications you could consider: While epinephrine will be the primary medication, you could also consider a nebulizer breathing treatment of 5.0 mg Albuterol and (maybe) 0.5 mg Ipratropium; this won’t deal with the airway compromise, but it will cause bronchodilation, and may help improve gas exchange. Additionally, giving a corticosteroid such as prednisone, solu-medrol (methylprednisolone) or dexamethasone (decadron) can help with swelling and inflammation.
- Airway management: This is for my ALS brethren. If the airway doesn’t respond to the epi, prepare to manage the airway using all the tools at your disposal. If you’re an airway management hotshot, you may be able to intubate before the airway closes off; Rapid Sequence Induction (RSI), utilizing a sedative and a paralytic may be needed. If you can’t intake, you may be performing a surgical cricothyrotomy.
Hey folks, thanks for reading. This post comes to you today from Silva, North Carolina, from the campus of Landmark Learning. Share your thoughts either here in the comments, or on Twitter using the tag #wwydwednesday.