Anaphylaxis

Definition

Anaphylaxis is a severe, potentially life-threatening allergic reaction that develops rapidly, usually over minutes to hours.

Criteria for Diagnosis:
Anaphylaxis is diagnosed if any of the following criteria are met:

1. Skin/Mucosal Symptoms + Systemic Compromise:

   • Urticaria, generalized itching/flushing, or edema of lips, tongue, uvula, or skin.

   • AND one of the following:

     • Respiratory distress or hypoxia.

     • Hypotension or cardiovascular collapse.

     • Associated symptoms of organ dysfunction (e.g., hypotonia, syncope, incontinence).
       
       

2. Two or More of the Following:

   • Skin/mucosal involvement.

   • Respiratory compromise.

   • Hypotension or associated symptoms.

   • Persistent gastrointestinal symptoms (e.g., cramps, vomiting).
     
     

3. Exposure to Known Allergen:

   • If the patient is exposed to a known allergen AND develops hypotension.
     
     

Note: If none of the above criteria are met, it is likely an allergic reaction and can be treated with simple antihistamines.

If Peri-Arrest (Impending Cardiac Arrest or Profoundly Hypotensive/Bradycardic):

1. IV Epinephrine:

   • Adult: 50 micrograms (0.05 ml of 1 mg/ml epinephrine vial) as a bolus.

   • Pediatrics: 1 mg.
     
     

2. Simultaneous ABC Management:

   • Airway, Breathing, Circulation.
     
     

3. Epinephrine Infusion:

   • Start at 1 microgram/min (0.1–0.3 microgram/kg/min for pediatrics; max 1.5 microgram/kg/min).

   • Titrate to achieve resolution.
     
     

If NOT Peri-Arrest:

1. IM Epinephrine:

   • Adult: 0.3–0.5 mg (0.01 mg/kg for pediatrics).

   • Repeat every 5 minutes (up to 3 doses if needed).
     
     

2. If No Improvement (After IM Epinephrine):

   • IV Epinephrine: 100 micrograms (0.1 ml of 1 mg/ml epinephrine vial diluted in 100 ml N/S over 5–10 minutes).

   • Pediatrics: 1 microgram/kg over 10 minutes.

   • Followed by Epinephrine Infusion: 1 microgram/min (0.1–0.3 microgram/kg/min for pediatrics; max 1.5 microgram/kg/min).
     
     

3. IV Fluids:

   • 1–2 L bolus (10–20 ml/kg for pediatrics).
     
     

4. Additional Medications:

   • Antihistamines: Avil (H1-antihistamine), H2-antihistamine if available.

   • Steroids: Any steroid to prevent recurrence.

   • Bronchodilators: Ventolin nebulization if wheeze/bronchospasm present.
     
     

5. If on Beta-Blockers & Not Improving:

   • Glucagon: 1–5 mg (adult).

1. Criteria for Discharge:

   • No need for IV epinephrine.

   • Stable for 4–6 hours post-treatment.
     
     

2. Home Medications:

   • Steroids: Prednisone 1 mg/kg/day divided twice a day for 3–5 days.

   • Antihistamine: H1-antihistamine (e.g., Loratadine, Cetirizine).

   • H2 Blocker: Famotidine 40 mg once a day (if available).

   • Calamine Lotion: For skin lesions as needed.
     
     

3. Follow-Up:

   • Medicine OPD follow-up in 3 days.

   • Identify and counsel patient to avoid triggers.

   • Explain the risk of biphasic reaction.

• EB Medicine Anaphylaxis

Author:

Editor: