- More than 50% of anaphylaxis cases are idiopathic; therefore, a high index of suspicion is needed to make the diagnosis in children.
- Airway compromise can occur rapidly.
- Epinephrine is the first-line medication for the treatment of moderate-to-severe anaphylaxis.
- In severe anaphylaxis if 2 to 3 fluid boluses (20 cc/kg) are given, as well as epinephrine; if hypotension persists, an epinephrine drip is indicated.
Anaphylaxis is a severe, potentially life-threatening hypersensitivity reaction characterized by skin or mucosal manifestations that include a pruritic rash, urticaria, or angioedema, respiratory compromise associated with airway edema and bronchospasm, and/or cardiovascular compromise that can result in distributive shock. It occurs within minutes to hours after exposure to an offending allergen. The estimated risk of anaphylaxis per person in the United States is 1% to 3%; this may be an underestimate of the true severity of the problem.1 Food allergy is the most common cause of anaphylaxis, and leads to approximately 150 fatalities in the United States each year.1 Since in over 50% of episodes of anaphylaxis cases no precipitating cause is identified, the emergency physician must have a high level of suspicion for the disorder in order to recognize the symptoms and initiate proper treatment.2
Anaphylaxis is an immunologic reaction. An initial exposure to an allergen results in the development of a specific IgE antibody to the antigen. The IgE antibody resides on the cell membrane of basophil and mast cells. When a subsequent exposure to the allergen occurs, the allergen binds to the IgE on the basophil and mast cells, and stimulates the release of multiple mediators, including histamine, leukotriene C4, prostaglandin D2, and tryptase. These mediators lead to increased production and release of respiratory secretions, increased bronchial smooth muscle tone, decreased vascular smooth muscle tone, and increased capillary permeability. An anaphylactoid reaction involves the release of similar mediators without involvement of the immune system. Intravenous (IV) contrast allergy is an example of an anaphylactoid reaction.
Food is the number one cause of anaphylaxis; More than 90% of food-related anaphylaxis is caused by exposure to nuts and shellfish.3,4 In infants, cow's milk and eggs are the most common causes of anaphylaxis.5 Once the food that caused the anaphylaxis is identified, thorough education of the parents and child is necessary to avoid reexposure.
Insect stings are a common cause of a localized allergic reaction and can also cause anaphylaxis. There is a fatality rate of fewer than 100 deaths per year in the United States.4
Drug-related allergies are quite common, but fortunately anaphylaxis from medications is relatively rare. The most common medications causing anaphylaxis are aspirin, NSAIDs, and β-lactam antibiotics. IV administration of medication has a higher incidence of anaphylaxis and more rapid onset of the anaphylactic symptoms.
Latex allergy is becoming an increasingly common cause of allergic reaction in children; it can occur following exposure to ...