GIM Question 28 Instructor

You are called to assess a patient on your ward who is complaining of an itchy rash (that appears urticarial), facial flushing and diarrhea shortly after taking penicillin.

  1. What reaction is this?
    This is an example of anaphylaxis.
    Anaphylaxis is an IgE-mediated type 1 hypersensitivity reaction. Symptoms are caused by the release of histamine and other inflammatory mediators from mast cells and basophils in response to a specific allergen. This is a medical emergency, as upper airway problems and shock can develop rapidly.
  2. What are the possible symptoms of this particular reaction?
    Symptoms of anaphylaxis can include:

    • Urticaria
    • Angioedema
    • Dyspnea, wheezing
    • Upper airway edema
    • Dizziness, syncope, hypotension
    • Nausea, vomiting, abdominal pain, diarrhea
    • Flush
    • Headache
    • Rhinitis
    • Substernal pain
    • Pruritus without rash
    • Seizure
  3. How would you manage this?
    The mainstay of treatment is ensuring the patient is stable and has a patent airway, and treating shock:

    • Call for help: get someone with advanced airway skills in the event of rapid upper airway problems
    • Stabilize ABCs
      • If difficulty breathing develops use orotracheal tube or nasotracheal tube (consider intubation in severe cases)
      • Ensure O2 supplementation – 100% O2 via non-rebreather face mask
      • Obtain IV access
      • Monitor vitals
    • Epinephrine 0.3-0.5mg IM of 1:1000
    • Ventolin (if wheezing occurs)
    • Antihistamines (give both)
      • Diphenhydramine 50mg IV (H1 receptor blocker, aka Benadryl)
      • Ranitidine 50mg IV (H2 receptor blocker)
    • Methylprednisone 1mg/kg IV can be given after stabilization – some evidence that this helps in preventing a second phase reaction
    • Monitor patient for the next 24 hours for a second phase reaction

Ellis AK and Day JH. Diagnosis and management of anaphylaxis. CMAJ. 2003, 169:307-311.

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