Monday, August 13, 2018

Adrenaline in Anaphylaxis

Anaphylaxis is a life-threatening emergency and is one of the most stressful medical conditions that an expedition medic could face. Fortunately, the condition is reversible with prompt administration of adrenaline by intramuscular injection.

Because the onset of anaphylaxis can be very fast, an adrenaline auto-injector can be very useful upon witnessing the first signs of a severe reaction.

Signs of a severe reaction include:

    • Swelling in the throat (altered voice, difficulty swallowing or breathing)

    • Wheezing

    •  Dizziness, feeling faint, tiredness (symptoms of low blood pressure)

The most commonly seen auto-injectors are still EpiPen®. Certainly, this brand is most commonly carried by children and adults in the UK setting. Therefore it may be that some participants on expeditions may carry these.

Figure 1 - EpiPen® Auto-Injector


All auto-injectors should be injected into the muscle of the outer thigh.

There has been a recent slight change in the guidance for administration for EpiPen®.

There is no change to the device or the drug (adrenaline); the change is in the instructions for use as outlined below:

    • Reduced injection time from 10 seconds down to 3 seconds – this is based on research confirming delivery of adrenaline for 3 seconds is sufficient.

    • Removal of the massage step after the injection – this step has been removed to simplify the process of administering EpiPen®.

The changes above are aimed to improve patient compliance.

Remember that anyone who uses an auto-injector must have had training in its use (as they are all slightly different). However, it is a drug that can be administered by a non-health care professional in the UK setting if required to treat a patient with anaphylaxis.

It is hoped that the manufacturers of the other auto-injectors (Jext and Emerade) available in the UK will also change their guidelines to match those of EpiPen®.

Wilderness Medical Training recommends the use of Emerade as the autoinjector of choice as each one contains 0.5mg adrenaline (Resus Council UK guideline dose) rather than the 0.3mg adrenaline dose in the EpiPen®.

The guidance for the Emerade auto-injector remains to hold the autoinjector against the thigh for 5 seconds.

Figure 2 - Technique for use of the Emerade Auto-injector


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