New Guidelines for Diagnosing and Treating Anaphylaxis

A taskforce from the European Academy of Allergy and Clinical Immunology (EAACI) has reviewed the published research and formulated a new set of comprehensive guidelines for diagnosing and treating anaphylaxis.

The document draws on four years of research published after the latest guidelines from the EAACI’s American equivalent, the American Academy of Allergy, Asthma and Immunology (AAAAI).

Still, its authors repeatedly note, much remains uncertain when it comes to diagnosing and treating anaphylaxis, so evidence in the report is ranked from I (best) to V (worst) and all recommendations are graded from A to D.

Among the most prominent features of the new guidelines is a simplified diagnosis tool that’s designed to be easy enough for all medical professionals to memorize and use.

The guidelines note that anaphylaxis is very likely if exposure to a known allergen results in (1) systolic blood pressure dropping 30% or more, (2) changes to the skin or mucosal tissue and either breathing trouble or falling blood pressure, or (3) any combination of any above symptom and gastrointestinal distress.

The EAACI recommends that all patients diagnosed with anaphylaxis be treated as quickly as possible with an injection of adrenaline administered to the muscles in the mid-to-outer thigh. After that, responders should remove the likely trigger if possible, and slowly position patients on their backs and elevate their limbs. High-flow oxygen should be administered by facemask in all cases.

Inhaled short-acting beta-2 agonists should be given as well to relieve symptoms of bronchoconstriction in patients with anaphylaxis.

Systemic antihistamines are commonly used in anaphylaxis, and the guidelines note that combinations of systemic H1- and H2-antihistamines may confer additional benefits over-and-above systemic H1-antihistamines alone in relieving some cutaneous symptoms.

The evidence for using systemic glucocorticosteroids, on the other hand, looks thin. Indeed, the guideline authors noted, the evidence for many standard treatments falls far short of optimal.

Take the recommendation to inject adrenaline as soon as possible in all cases of anaphylaxis. It’s the cornerstone of every set of anaphylaxis guidelines, but the EAACI report rates the evidence to support it a “IV” and grades the recommendation a “C.”

The recommendation that the suspected trigger be removed appears to have no supporting evidence beyond common sense and it thus carries a “D” rating — just like the common-but-unsubstantiated recommendation that adrenaline injections be spaced at least five minutes apart.

“Systematic reviews of the anaphylaxis literature have revealed a lack of high-quality evidence in [many areas] preventing the development of firm recommendations. It is important that these gaps are prioritized to maximize the benefit of future research to patient care,” the guideline authors wrote.

“Large prospective cohort studies of patients at risk of anaphylaxis in real-life settings are required to provide a clearer understanding of the magnitude of risk associated with each factor to allow us to personalize avoidance advice and auto-injector prescription,” the authors wrote.

Moving to the recommendations for long-term management, the picture becomes even murkier.

Nearly all of the recommendations‑‑other than providing venom immunotherapy to people with venom allergies‑‑hinge on level V evidence and carry grade D ratings, and the guideline authors advocate still more research.