What is the management of Anaphylaxis?

From the Guidelines

Anaphylaxis management requires immediate recognition and treatment with epinephrine as the first-line therapy, which should be administered promptly without delay to reduce morbidity and mortality. The most recent and highest quality study, published in 2020 in the Journal of Allergy and Clinical Immunology 1, emphasizes the importance of administering epinephrine as the first-line pharmacotherapy for uniphasic and/or biphasic anaphylaxis. For adults, administer 0.3-0.5 mg of epinephrine (1:1000 concentration) intramuscularly into the mid-outer thigh; for children, use 0.01 mg/kg up to 0.3 mg. This should be repeated every 5-15 minutes if symptoms persist.

Key Considerations

• Position the patient supine with legs elevated unless respiratory distress is present.
• After epinephrine administration, provide supplemental oxygen (8-10 L/min) and establish IV access for fluid resuscitation with normal saline (1-2 L for adults, 20 mL/kg for children).
• Second-line medications include antihistamines (diphenhydramine 25-50 mg IV/IM for adults) and corticosteroids (methylprednisolone 1-2 mg/kg IV), though these do not replace epinephrine.
• For bronchospasm, add albuterol via nebulizer.
• Monitor vital signs continuously and be prepared for advanced airway management if needed.

Post-Treatment Care

• Observe patients for at least 4-6 hours, with severe cases requiring 24-hour observation due to risk of biphasic reactions.
• Patients should be discharged with an epinephrine auto-injector, an action plan, and follow-up with an allergist, as recommended by the 2020 practice parameter update 1.
• Education on anaphylaxis, including avoidance of identified triggers, presenting signs and symptoms, biphasic anaphylaxis, treatment with epinephrine, and the use of epinephrine auto-injectors, is crucial for patients and their families.

From the FDA Drug Label

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action Epinephrine acts on both alpha and beta-adrenergic receptors. 12. 2 Pharmacodynamics Through its action on alpha-adrenergic receptors, epinephrine lessens the vasodilation and increased vascular permeability that occurs during anaphylaxis, which can lead to loss of intravascular fluid volume and hypotension Through its action on beta-adrenergic receptors, epinephrine causes bronchial smooth muscle relaxation and helps alleviate bronchospasm, wheezing and dyspnea that may occur during anaphylaxis Epinephrine also alleviates pruritus, urticaria, and angioedema and may relieve gastrointestinal and genitourinary symptoms associated with anaphylaxis because of its relaxer effects on the smooth muscle of the stomach, intestine, uterus and urinary bladder

Anaphylaxis management with epinephrine (IM) involves:

• Lessening vasodilation and increased vascular permeability
• Relieving bronchospasm, wheezing, and dyspnea
• Alleviating pruritus, urticaria, and angioedema
• Relieving gastrointestinal and genitourinary symptoms Epinephrine is administered parenterally and has a rapid onset and short duration of action 2.

From the Research

Anaphylaxis Management

• The key to managing anaphylaxis is early epinephrine administration, which can improve outcomes and prevent progression to severe and fatal anaphylaxis 3, 4, 5.
• Delayed or lack of administration of epinephrine is associated with fatal reactions 3, 6.
• Positioning in a recumbent supine position, airway management, and intravenous fluids are essential in the management of anaphylaxis 3, 4.
• Antihistamines and glucocorticosteroids should not be prescribed in place of epinephrine, but may be used as adjunct medications after epinephrine administration 3, 7.
• β-adrenergic agonists by inhalation are indicated for bronchospasm associated with anaphylaxis despite optimal epinephrine treatment 3.

Long-term Management

• Long-term management of anaphylaxis includes the identification and avoidance of triggers, identification of cofactors, such as mast cell disorders, patient, parent, and caregiver education, and interventions to reduce allergen sensitivity 3.
• Consultation with an allergist/immunologist is recommended when necessary 3.
• Developing an emergency action plan, referral to an allergist, and patient education on avoidance of triggers and appropriate use of an epinephrine auto-injector are important aspects of long-term management 7.

Treatment Outcomes

• Patients treated with prehospital epinephrine are less likely to have uncontrolled reactions, receive intravenous fluids in the emergency department, and be admitted after the reaction 6.
• Patients treated with prehospital antihistamines may also have a beneficial effect, but the use of corticosteroids in anaphylaxis should be revisited 6.
• The incidence of anaphylaxis in the United States is 2.1 per 1,000 person-years, and most anaphylactic reactions occur outside the hospital setting 7.