Question: In studying for this year’s recert, I started to wonder why the administration of intramuscular epinephrine was being advocated for a first line drug in the management of an arrest where the patient was suspected to be suffering from anaphylaxis. The impression from the protocol is that this procedure should be given priority over starting an IV or an IO. Given that as a routine course in all arrests, an ACP will usually manage to initiate an IV / IO and administer epinephrine (1.0 mg – twice the dose that would be given IM) early in the call, it doesn’t seem to make sense to delay the initiation of the line.

With few hands on scene, and the PCP partner performing CPR, the ACP will only likely be able to perform one procedure during the two minutes between rhythm analyses – draw up and deliver epi IM or initiate an IV and deliver epi IV – but probably not both. Since the patient was likely suffering profound vasodilation prior to the arrest, there is low likelihood that there would be much effectiveness in circulating the half millilitre of fluid that is administered IM into a deltoid using CPR alone (which, at best, is only 25% as effective as the heart pumping on it’s own). The introduction of epinephrine directly into the bloodstream would likely have a much higher probability of achieving systemic circulation and effect as compared to the IM injection.

The recommendation seems to stem from an interpretation of Part 12 of the 2010 AHA ECC guidelines (Cardiac Arrest in Special Circumstances) where the use of IM epinephrine in arrests of suspected anaphylactic etiology is advised as a modification in the management of a BLS arrest. The recommendation is not present in the modifications in the management of an ALS arrest where, conversely, it is advised that epinephrine is administered by IV where a line is present. In fact, the one recommendation for ALS modification in the management of anaphylactic arrests in the AHA ECC guidelines is absent from our protocols. Currently, a fluid bolus is only indicated where the patient presents in PEA, however, the AHA ECC guidelines make the recommendation that “Vasogenic shock from anaphylaxis may require aggressive fluid resuscitation (Class IIa, LOE C).”

I understand that OBHG MAC might have apprehensions in delaying the administration of epinephrine in circumstances where an IV or IO could not be initiated in short order, however, would it not be more effective to use IM epinephrine as a backup where the line could not be initiated quickly (as in the case with Glucagon vs. IV Dextrose)? The IM administration would also have a higher likelihood of success if given once optimal circulation due to CPR was achieved (which would not occur until a couple minutes into the call).

Thanks for your consideration!