Anaphylaxis: Expanding our perspective

This month in our “Guidelines to Practice” series, Weller and Hsieh review the 2020 practice parameter update on anaphylaxis.^1,2 I suspect that most of us have a Frank Netter-like caricatured image of the patient with anaphylaxis (aka anaphylactic shock): mottled skin with some flush, swollen lips, some urticaria, hypotensive, tachycardic with wheezing heard on lung exam on the verge of cardiovascular collapse. But as highlighted by Weller and Hsieh, this is an extreme presentation on the spectrum of severity of anaphylaxis.

As the use of infused new protein-based medications increases across all specialties, we are spending more time reading package inserts and using drug databases to familiarize ourselves with the possible adverse effects of the medications. And we often find anaphylaxis listed as a rare but reported side effect. But as Weller and Hsieh point out, anaphylaxis is not always the extreme scenario we learned about in medical school. Rather, there is a range of far milder allergic infusion reactions that are nonetheless anaphylaxis.

This is not to minimize the potential impact of these reactions on patients and on what we should think about before prescribing these medications. While corticosteroid and antihistamine pretreatment is understandably provided before infusion of medications that have a perceived or recognized risk of hypersensitivity reactions, we still lack studies clearly demonstrating that these protocols reduce the occurrence of anaphylaxis.

Instructive from reading the summary of the practice update is the strong recommendation for the administration of epinephrine, and the reminder that some patients experience biphasic anaphylaxis—a potentially serious delayed occurrence warranting prolonged observation of some patients after the initial anaphylactic event has resolved. Interestingly, administration of glucocorticoids at the time of the initial allergic reaction does not seem to prevent this second reaction.

For those of us who don’t deal with severe allergic reactions on a daily basis, but do care for patients at risk of having one as a result of our therapeutic interventions, the paper by Weller and Hsieh is worth reading.

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