The ALS guidelines for managing anaphylaxis have just been updated. It's a good time to both describe the changes, as well as explain why they were changed.
First, what was changed?
The ALS treatment for anaphylaxis has been changed from subcutaneous epinephrine to intramuscular, as well specifying injection in the thigh.
Let me show you the exact changes:
In addition, the guideline for allergic reaction was also changed:
Of course, the pediatric guidelines were changed as well, simplifying the dosing, and changing the route:
Okay, but why were the guidelines changed?
The use of SQ epi for anaphylaxis has been around for a while, and had previously been seen as the standard of care. EMT-Basics could use the Epi-Pen, and it may have been assumed that this was solely because they had to use a simpler, "fool-proof" system, while the ALS providers were trained to administer the standard treatment.
Ironically, though, the EMT-Basics have been the ones who have been providing the "state-of-the-art" therapy, while ALS providers have been held back!
Epi needs to go IM, in the thigh.
The best evidence shows that epinephrine is best given IM, in the thigh.
For example, in this study the researchers compared the levels of epinephrine in the blood after giving it either subcutaneously or intramuscularly, and either in the thigh or deltoid area.
This graph explains it all. The orange and yellow lines represent epinephrine given IM, in the thigh. The serum concentrations are clearly more elevated than the other methods. By contrast, SQ epi in the arm (green line) doesn't bump epinephrine levels much higher than the placebo injections!
What about Benadryl & Solu-Medrol?
There are no changes in the guidelines regarding these medications.
In fact, it's worth re-emphasizing that these medications are just adjunct treatments for anaphylaxis, and some experts do not consider them essential. I reviewed in a recent post ("Anaphylaxis Knowledge Among Paramedics") the misunderstandings that some paramedics have about this, and also about the contraindications for epinephrine in anaphylaxis.
(Spoiler: There are no contraindication to epinephrine in anaphylaxis.)
The Bottom Line
Paramedics, starting now, need to treat anaphylaxis with intramuscular epinephrine, in the thigh.
For the full Paramedic Treatment Guidelines, go to the website to download the updated protocols (pdf). EMT-Basics, on the other hand, can just keep using their "old" protocols.