What is the management of anaphylaxis?

Anaphylaxis Management

Immediate administration of intramuscular epinephrine into the mid-outer thigh is the cornerstone of anaphylaxis management and should be the first action taken when anaphylaxis is suspected. 1

Recognition and Initial Management

• Anaphylaxis is a severe, life-threatening systemic reaction resulting from sudden release of mediators from mast cells and basophils 2
• Clinical criteria for diagnosis include:
  • Acute onset with skin/mucosal involvement plus respiratory compromise or reduced blood pressure
  • The more rapidly anaphylaxis develops, the more likely it is to be severe and potentially life-threatening 2

Emergency Treatment Algorithm

1. First-Line Treatment: Epinephrine

   • Dose: 0.01 mg/kg of 1:1000 (1 mg/mL) solution 1
   • Maximum dose: 0.3 mg in children, 0.5 mg in adults 1
   • Route: Intramuscular (IM) injection into anterolateral thigh 1
   • Timing: Administer immediately upon recognition of anaphylaxis 1
   • Repeat: Every 5-15 minutes if symptoms persist 1
   • Auto-injector dosing:

     • 25 kg: 0.3 mg auto-injector

     • 10-25 kg: 0.15 mg auto-injector 1

2. Patient Positioning

   • Place patient in recumbent position with elevated lower extremities 1
   • If breathing difficulty is present, allow patient to sit upright 1

3. Airway Management

   • Establish and maintain airway 1
   • Consider endotracheal intubation or cricothyrotomy if necessary 1

4. Oxygen Administration

   • Administer oxygen at 6-8 L/min 1
   • Especially important for prolonged reactions or patients requiring multiple epinephrine doses 1

5. Fluid Resuscitation

   • Normal saline: 1-2 L bolus for adults (5-10 mL/kg in first 5 minutes) 1
   • Children: 20 mL/kg bolus, up to 30 mL/kg in first hour 1
   • Repeat as needed based on response 1

Adjunctive Medications (After Epinephrine)

1. Corticosteroids

   • Hydrocortisone: 200 mg IV (adult dose) 1
   • Prednisone: 0.5-1 mg/kg orally for 2-3 days 1
   • Note: Slow onset of action, not effective for acute management 1

2. Antihistamines

   • H1 antagonists: Diphenhydramine 1-2 mg/kg IV/IM (max 50 mg) every 6 hours 1
   • H2 antagonists: Ranitidine 1 mg/kg IV twice daily 1
   • Note: Not effective for respiratory or cardiovascular manifestations 1

3. For Bronchospasm

   • Nebulized albuterol: 2.5-5 mg in 3 mL saline 1

4. For Refractory Hypotension

   • Vasopressors: Dopamine 2-20 μg/kg/min 1
   • For patients on beta-blockers: Glucagon 1-5 mg IV over 5 minutes 1

Monitoring and Observation

• Monitor patients for at least 4-6 hours after initial symptoms resolve 1
• Watch for biphasic reactions (recurrence of symptoms after initial resolution) 1
• Longer observation recommended for:
  • Severe initial reactions
  • Patients requiring multiple doses of epinephrine 1

Discharge Planning

1. Prescribe epinephrine autoinjectors (2 devices) 1
2. Provide training on proper use of autoinjectors 1
3. Create personalized anaphylaxis emergency action plan 1
4. Arrange follow-up with an allergist-immunologist 2, 1

Special Considerations

• Intravenous epinephrine should be used with extreme caution due to significantly higher risk of cardiovascular adverse events and overdose compared to IM administration 3
• Patients on beta-blockers may have reduced response to epinephrine and may require glucagon 1
• Infants <15 kg require careful epinephrine dosing as standard autoinjector doses may be high 1

Common Pitfalls to Avoid

1. Delaying epinephrine administration - No reliable way to predict which reactions will become life-threatening 4
2. Using antihistamines or corticosteroids as first-line treatment - These are adjunctive therapies only and should never delay epinephrine 4
3. Administering epinephrine intravenously without proper monitoring - IV bolus epinephrine has 8.7 times higher risk of cardiovascular complications and significantly higher risk of overdose compared to IM administration 3
4. Discharging patients too early - Biphasic reactions can occur hours after initial symptoms resolve 1, 5
5. Failing to prescribe autoinjectors or provide proper training at discharge 1

Epinephrine works through both alpha and beta-adrenergic receptors to reverse the pathophysiology of anaphylaxis - reducing vasodilation and vascular permeability, relaxing bronchial smooth muscle, and alleviating cutaneous and gastrointestinal symptoms 6.