This article was developed by Mylan Specialty, L.P.

Introduction

Anaphylaxis is increasing in prevalence and has important health implications in the United States.

Although the exact incidence is unknown, anaphylactic reactions may involve up to 2% of the population.¹ Moreover, the annual incidence of anaphylaxis and related conditions such as food allergy and asthma appears to be increasing.^2-6

Evidence also suggests dramatic increases in emergency department visits, hospitalization, hospital outpatient visits and physician office visits as well.^3,5 Despite the availability of diagnostic criteria and management guidelines, anaphylaxis is often under-recognized and/or under-treated in the United States.^4,7-9

Further, the delayed administration of epinephrine is an important problem in anaphylaxis management that has been noted to contribute to fatalities.^8,10-14 Given the potentially fatal consequences of anaphylaxis, health care professionals must not only be able to recognize and treat anaphylaxis promptly, but also to educate their patients on how to manage this life-threatening condition.

Food is the major cause of anaphylaxis in the United States, with recent data associating severe reactions, most commonly in children, with allergy to tree nuts, peanuts, shellfish, soy, etc.

What is Anaphylaxis?

In 2005, the National Institute of Allergy and Infection Disease (NIAID) and the Food Allergy and Anaphylaxis Network (FAAN) developed a consensus definition for anaphylaxis (Table 1).⁹ The symptoms of anaphylaxis are variable and can affect multiple organ systems, including the gastrointestinal tract and cardiovascular system.^15-17

Skin signs such as flushing, itching, urticarial and rash occur in up to 90% of patients, while respiratory symptoms, including dyspnea, wheeze and upper angioedema, occur in up to 60% of patients.⁸

However, anaphylaxis may present as an acute cardiac or respiratory event, or with hypotension as the only manifestation.⁸ The onset of symptoms varies from a few seconds or minutes after contact with the elicitor to several hours (depending on the route of exposure and degree of sensitization),¹⁶ but the majority of events occur within two hours of exposure.¹⁸

The faster anaphylaxis develops, the more likely the reaction is to be severe and potentially life-threatening.⁸ A pattern of biphasic anaphylaxis has also been described in which symptoms recur after the apparent resolution of the initial episode, which merits treatment similar to the initial episode.^8,19

Anaphylaxis is estimated to be fatal in 0.7% to 2% of cases.^20,21 Death can occur within minutes of the onset of symptoms.⁷ Deaths due to anaphylaxis are usually attributed to respiratory obstruction or cardiovascular collapse, or both.^11,22

Anaphylaxis Triggers

Food is the major cause of anaphylaxis in the United States,² with recent data associating severe reactions, most commonly in children, with allergy to tree nuts, peanuts, shellfish, soy, and fin fish.²³ Medicines are among the leading causes of anaphylaxis, with beta-lactam antibiotics most commonly implicated.^{8,10,15,24,25} Anaphylactic reactions to insect stings have occurred in 1% of children and 3% of adults^8,26,27 and are associated with a high probability of recurrence.²⁸

Other important causes of anaphylaxis include latex allergy^15,29 and perioperative anaphylaxis.^8,10,30

Managing Anaphylaxis

Prompt recognition and management of the signs and symptoms of anaphylaxis are the key to managing anaphylaxis.⁸

Immediate interventions for patients experiencing anaphylaxis include assessment of airway and breathing, circulation, and level of consciousness; administration of intramuscular epinephrine; and placement of the patient in a supine position in order to slow the progression of hemodynamic compromise.⁸

Intramuscular (IM) epinephrine injection is first-line treatment in all cases of anaphylaxis.^4,8,22 Along with the use of oxygen, is considered the most important therapeutic agent administered for anaphylaxis.⁸ The appropriate dose of IM epinephrine should be administered immediately at the onset of symptoms, even if the diagnosis is uncertain.^4,8,22 At a concentration of 1:1000, the recommended dose of epinephrine via auto-injector is 0.15 mg for patients weighing 10-25 kg and 0.3 mg for patients weighing greater than 25 kg.⁴

Epinephrine may be administered every 5 to 15 minutes as necessary, and if symptoms progress or recur (i.e., biphasic reaction), repeat epinephrine dosing is recommended over adjunctive treatments.^4,8 Although up to a third of patients require more than one dose,³¹ additional measures (intravenous epinephrine, volume replacement, vasopressors) may be needed in patients not responding to multiple doses.⁸

Supportive care with nebulized therapy, vasopressors, antihistamines, or corticosteroids may be beneficial for specific symptoms but are not replacements for epinephrine and should be administered only after epinephrine.⁸ Patients should be observed after acute treatment to monitor for biphasic reactions or possible recurrence as the epinephrine wears off.²² Because the initial clinical presentation cannot reliably predict biphasic or protracted anaphylaxis, observation periods must be individualized.⁸

Conclusion

In order to manage the growing population of allergic individuals in the United States, physicians and office staff must maintain a well-established plan, clinical proficiency, and the proper equipment in treating anaphylaxis.

Education may be the most important tool for patients at risk for anaphylaxis, and developing a written action plan is essential for all patients who have experienced anaphylaxis.^7,8 The proper use of self-administered epinephrine is an essential component of patient education. Patients should be counseled to store epinephrine auto-injectors properly (avoiding temperature extremes) and to be cognizant of the expiration date.²²

Other key components include education regarding allergen avoidance, including hidden allergens and cross-reactivities as well as developing an anaphylaxis action plan.^7,8,22 To that end, patients with a history of anaphylaxis should be considered for referral to an allergy/immunology specialist for evaluation and long-term management.⁸

Dr. Lanier is a clinical professor of pediatrics at the University of North Texas Health Science Center in Fort Worth, Texas. This article is sponsored by Mylan Specialty, L.P.

Editor’s Note: Emergency physician Marc Finder has long advised his patients to store an epinephrine auto-injector in the silverware drawer. That way, in an emergency in which the patient has to tell someone to go fetch it, it’s easy to find. “A house typically has only one (easily located) kitchen,” says Dr. Finder, “and a kitchen typically has one (easily identified) silverware drawer.”

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