Anaphylaxis
| Anaphylaxis | |
| ICD-10 | T78.2 |
|---|---|
| DiseasesDB | 29153 |
| MeSH | D000707 |
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Anaphylaxis Microchapters |
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Anaphylaxis On the Web |
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American Roentgen Ray Society Images of Anaphylaxis |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: Anaphylactic reaction
Overview
Anaphylaxis is an acute systemic (multi-system) and severe Type I Hypersensitivity allergic reaction in humans and other mammals. The term comes from the Greek words ana (against) and phylaxis (protection).[1] Anaphylaxis occurs when a person or animal is exposed to a trigger substance, called an allergen, to which they have already become sensitized. Minute amounts of allergens may cause a life-threatening anaphylactic reaction. Anaphylaxis may occur after ingestion, skin contact, injection of an allergen or, in rare cases, inhalation.[2]
Anaphylactic shock, the most severe type of anaphylaxis, occurs when an allergic response triggers a quick release from mast cells of large quantities of immunological mediators (histamines, prostaglandins, leukotrienes) leading to systemic vasodilation (associated with a sudden drop in blood pressure) and edema of bronchial mucosa (resulting in bronchoconstriction and difficulty breathing). Anaphylactic shock can lead to death in a matter of minutes if left untreated.
An estimated 1.24% to 16.8% of the population of the United States is considered "at risk" for having an anaphylactic reaction if they are exposed to one or more allergens, especially penicillin and insect stings. Most of these people successfully avoid their allergens and will never experience anaphylaxis. Of those people who actually experience anaphylaxis, up to 1% may die as a result.[3] Anaphylaxis results in fewer than 1,000 deaths per year in the U.S. (compared to 2.4 million deaths from all causes each year in the U.S.[2]). The most common presentation includes sudden cardiovascular collapse (88% of reported cases of severe anaphylaxis).
Researchers typically distinguish between "true anaphylaxis" and "pseudo-anaphylaxis." The symptoms, treatment, and risk of death are identical, but "true" anaphylaxis is always caused directly by degranulation of mast cells or basophils that is mediated by immunoglobulin E (IgE), and pseudo-anaphylaxis occurs due to all other causes. The distinction is only important for researchers who are studying mechanisms of allergic reactions. Due to the word "pseudo", it may frustrate patients who feel they are being told that a life-threatening allergic reaction isn't "real".
Treatment
Planning for treatment
The Asthma and Allergy Foundation of America advises patients prone to anaphylaxis to have an "allergy action plan" on file at school, home, or in their office to aid others in case of an anaphylactic emergency, and provides a free "plan" form anyone can print. Action plans are considered essential to quality emergency care. Many authorities advocate immunotherapy to prevent future episodes of anaphylaxis."allergy fact sheet" Immunotherapy with Hymenoptera venoms is especially effective and widely used throughout the world and is accepted as an effective treatment for most patients with allergy to bees, wasps, hornets, yellow jackets, white faced hornets, and fire ants. "WHO guidelines"
Beta-blockers may aggravate anaphylactic reactions and interfere with treatment.
Prevention
References
- ↑ "Anaphylaxis." Etymology. Oxford English Dictionary. http://dictionary.oed.com.
- ↑ "Anaphylaxis." Health. 17 January 2002 . AllRefer.com . 29 Jan 2007 <http://health.allrefer.com/health/anaphylaxis-info.html>.
- ↑ Neugut, Alfred, Anita Ghatak and Rachel Miller. "Anaphylaxis in the United States: An Investigation Into Its Epidemiology." Arch Intern Med. 161.108 January 2001 15-21. 29 January 2007 <http://archinte.ama-assn.org/cgi/content/full/161/1/15>.
External links
- American Academy of Allergy and Immunology
- The Food Allergy & Anaphylaxis Network
- alert4allergy.org - a free service for people in Britain with food allergy.
- - UK national registered charity and support group for people at risk from anaphylaxis
- A discussion forum for UK peanut anaphylaxis sufferers
- Public discussion forums and support group for allergy/anaphylaxis sufferers
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