Who Needs Epinephrine? Anaphylaxis, Autoinjectors, and Parachutes

Abstract

International guidelines stipulate that intramuscular (IM) epinephrine (adrenaline) is the first-line treatment for anaphylaxis, with an established good safety profile. The availability of epinephrine autoinjectors (EAI) has greatly facilitated the lay administration of IM epinephrine in community settings. However, key areas of uncertainty remain around epinephrine usage. These include variations in prescribing EAI, what symptoms should prompt epinephrine administration, whether emergency medical services (EMS) need to be contacted after administration, and whether epinephrine administered via EAI reduces mortality from anaphylaxis or improves quality of life measures. We provide a balanced commentary on these issues. There is increasing recognition that a poor response to epinephrine, particularly after 2 doses, is a useful marker of severity and the need for urgent escalation. It is likely that patients who respond to a single epinephrine dose do not require EMS activation or emergency department transfer, but data are needed to demonstrate the safety of this approach. Lastly, patients at risk of anaphylaxis must be counseled against over-reliance on EAI alone.

Keywords: Anaphylaxis; Autoinjector; Epinephrine; Outcomes; Prescribing.

FIGURE 1.

Spectrum of symptom severity in allergic reactions and anaphylaxis. Indicative symptoms taken from Dribin et al. Reproduced under Creative Commons CC-BY-NC-ND license. GCS, Glasgow Coma Scale; WOB, work of breathing.

FIGURE 2.

World Allergy Organization 2020 criteria for the diagnosis of anaphylaxis. Reproduced under Creative Commons CC-BY-NC-ND license.

FIGURE 3.

Possible algorithm for home management of anaphylaxis in individuals in whom such an approach may be appropriate (as per Table III). Adapted from Casale et al. EAI, Epinephrine autoinjectors; EMS, emergency medical services.