Anaphylactic Shock

Question 1

Pathogenesis of anaphylactic shock

Answer 1

• Type 1 IgE mediated hyperensitivity reaction
• TH2 driven IgE production following primary allergen exposure
• Re-exposure - biphasic inflammatory response
  
  • Early phase - minutes
    
    • IgE cross-linking causing mast cell degranuation
    • Vasoactive mediator release
      
      • Histamine and tryptase
    • Lipid mediator synthesis
      
      • Leukotrienes cause increased vascular permeability and bronchial constriction
      • Prostacyclin
    • Chemokines (i.e. eotaxin)
      
      • Promote leukocyte recruitment
  • Late phase - 2-24 hours
    
    • Eosinophils recruited in early phase
    • Release enymes and stimulate mast cells
    • Amplify and sustain the initial response

Question 2

Presentation of anaphylaxic shock

Answer 2

• Sweating
• Vomiting
• Urticaria, itching and oedema
• Wheeze, laryngeal obstruction, cyanosis
• Tachycardia, hypotension
• Possible improvement and then deterioration as late phase initiates

Question 3

Management of anaphylatic shock

Answer 3