My Peripheral Brain

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My Peripheral Brain *

"I consider that a man's brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things, so that he has a difficulty in laying his hands upon it. Now the skillful workman is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work, but of these he has a large assortment, and all in the most perfect order. It is a mistake to think that that little room has elastic walls and can distend to any extent. Depend upon it there comes a time when for every addition of knowledge you forget something that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones."

~Sherlock Holmes

Allergy Adam Broughton Allergy Adam Broughton

Anaphylaxis

Yeah, about the only thing we care about in the ED allergy related is anaphylaxis. Sure, hundreds of patients will enter your ED with weird rashes, obvious hives, bug bites, bee stings, and poison ivy that never even come close to the definition of an emergency ("but it is to me!" your patients will say). Yet, the only thing you are really responsible for doing in these cases is make sure you're not missing is....Anaphylaxis. That's why I always make sure to include a negative ROS that includes those questions that pertain to true anaphylaxis. But what is anaphylaxis really???

  • The America Academy of Allergy and Asthma (yes, the AAAA) says, "Anaphylaxis (an-a-fi-LAK-sis) is a serious allergic response that often involves swelling, hives, lowered blood pressure and in severe cases, shock. If anaphylactic shock isn't treated immediately, it can be fatal."

  • Merriam-Webster writes, "hypersensitivity (as to foreign proteins or drugs) resulting from sensitization following prior contact with the causative agent."

  • The National Institute of Allergy and Infectious Diseases most correctly states, "Anaphylaxis is a serious allergic reaction that involves more than one organ system (for example, skin, respiratory tract, and/or gastrointestinal tract). It can begin very rapidly, and symptoms may be severe or life-threatening."

The most salient points being, 1) it is life-threateningly serious, 2) must involve more than one organ system, and 3) can be very rapid. Therefore, it requires expedient recognition and treatment. 

We all know that the definative treatment is epinephrine, but unfortunately since we give it so infrequently (like more often in coding dead patients), sometimes we are slow to pull the epi-trigger. This, of course, could be a fatal mistake, so here is a quick overview. 

  1. The starting dose for epiniphrine (the epinephrine autoinjector dose) is 0.3mg deep IM. I suggest you encourage your ED to carry autoinjectors because it can take a surprisingly long time for your nurses to draw this up. 

  2. For patients with severe anaphylaxis give 0.5mg epinephrine IM in the thigh (best absorption here).

  3. If the patient still needs epinephrine (multiple IM doses needed) and you need an epinephrine drip. Recommended IV epinephrine is to start at 1-4mcg/min or 0.1mg over 5 min.

  4. Unfortunately, an epi drip can be similarly difficult to obtain from pharmacy. A trick of the trade can be found at ALiEM here to make a "dirty epi drip."  

    • Get 1mg of epinephrine (from code cart)

    • Inject this 1mg of epi into 1,000 mL normal saline bag which = concentration of 1 mcg/mL

    • Rune wide open until symptom response and/or patient stabilizes

    • Wide open administration of a “dirty” epinephrine drip results through 18G IV cathaeter is about 20-30 mcg/min when administered wide open. This can be titrated down when the symptoms improve. 1ml per min (60ml/hr) would be a 1mcg per min recommended starting dose. 

  5. Give an H1 blocker (like Benedryl) and an H2 blocker (like Pepcid) to help urticaria although no benefit in anaphylaxis has been demonstrated.

  6. Glucocorticoids similarly have not been of proven benefit but routinely given. 

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