What is the immediate treatment for a patient experiencing anaphylaxis?

Immediate Treatment for Anaphylaxis

The immediate treatment for anaphylaxis is prompt administration of intramuscular epinephrine in the mid-outer thigh, which should be given as soon as anaphylaxis is recognized. 1, 2

Initial Assessment and Management

1. First-line treatment: Epinephrine

   • Administer epinephrine intramuscularly in the mid-outer thigh (vastus lateralis muscle)
   • Dosing:
     • Adults and children ≥30 kg: 0.3-0.5 mg
     • Children <30 kg: 0.01 mg/kg (maximum 0.3 mg) 2
   • If using an autoinjector:
     • Weight 10-25 kg: 0.15 mg epinephrine autoinjector
     • Weight >25 kg: 0.3 mg epinephrine autoinjector 1
   • May repeat dose every 5-15 minutes if symptoms persist 1

2. Simultaneously:

   • Activate emergency response system/call 911 1
   • Position patient appropriately:
     • If hypotensive: Lay flat with legs elevated
     • If respiratory distress: Semi-sitting position 2
   • Remove potential triggers if possible 2

Secondary Interventions (after epinephrine)

1. Airway management

   • Administer 100% oxygen if respiratory distress is present 2
   • Monitor for signs of airway compromise

2. Circulatory support

   • Establish IV access with large-bore catheter
   • Administer IV fluids (0.9% saline or lactated Ringer's) for hypotension or incomplete response to epinephrine 1, 2

3. Adjunctive medications (only after epinephrine administration)

   • H1 antihistamine: Diphenhydramine 1-2 mg/kg or 25-50 mg IV/IM 1
   • For persistent bronchospasm: Nebulized albuterol 2.5-5 mg in 3 mL saline 1
   • Consider H2 antihistamine: Ranitidine 1 mg/kg IV (adults: 50 mg) 1
   • Consider systemic glucocorticosteroids for potential biphasic reactions 1, 2

Management of Refractory Anaphylaxis

For severe cases not responding to initial treatment:

• Consider repeat epinephrine doses every 5-15 minutes 1
• For hypotension refractory to volume replacement and epinephrine: Consider vasopressor infusion (e.g., dopamine 2-20 μg/kg/min) 1
• For patients on beta-blockers with poor response: Consider glucagon 1-5 mg IV 1

Post-Acute Management

• Observe patient for at least 4-6 hours after symptom resolution 1, 2
• Longer observation (or admission) for severe reactions or those requiring multiple epinephrine doses 1
• Monitor for biphasic reactions, which can occur up to 72 hours later 2

Common Pitfalls to Avoid

1. Delaying epinephrine administration - This is associated with increased mortality and morbidity 2, 3
2. Using antihistamines or corticosteroids as first-line treatment - These are adjunctive only and should never replace epinephrine 2
3. Administering epinephrine intravenously (except in cardiac arrest) - IM route is safer and preferred 1
4. Allowing patients to remain standing or walking - This can worsen hypotension 2
5. Insufficient observation time - Biphasic reactions can occur hours after initial resolution 1, 2

Discharge Planning

• Prescribe epinephrine autoinjector (at least 2 doses) 1, 2
• Provide anaphylaxis emergency action plan 2
• Educate on proper autoinjector use with demonstration 2
• Arrange follow-up with allergist/immunologist 2

Remember that early administration of epinephrine is the most critical intervention for preventing fatal anaphylaxis. Delays in epinephrine administration are associated with increased mortality, particularly in patients with asthma, adolescents, and those with food allergies, especially to peanuts and tree nuts 1.