Management of Anaphylaxis

Question 1

Pathophysiology of anaphylaxis?

Answer 1

• Allergen binds membrane-bound IgE on mast cells
• Causes release of histamine, tryptase and vasoactive mediators
• Results in vasodilation and increased capillary permeability:
  
  • Hypotension
  • Bronchoconstriction

Question 2

What is anaphylaxis in summary?

Answer 2

IgE-mediated mast cell degranulation

Question 3

What are anaphylactoid reactions in summary?

Answer 3

Non-IgE mediated mast cell degranulation

Question 4

Causes of anaphylaxis?

Answer 4

• Peanuts
• Shellfish
• Wasp venom
• Penicillin
• Latex

Question 5

Causes of anaphylactoid reactions?

Answer 5

• Aspirin, NSAIDs
• Radiocontrast media
• Exercise
• Cold

Question 6

Differentials for anaphylaxis?

Answer 6

• Septic shock
  
  • Raised WCC, fever, no allergen exposure
• Cardiogenic shock
  
  • Elevated CK and troponin, CXR signs of HF
• Vasovagal syncope
  
  • Lack of cutaneous manifestations

Question 7

Describe the management of anaphylaxis?

Answer 7

• Prevent further contact with allergen
• Ensure airway patency
• Adrenaline IM 500 mcg (0.5ml 1:1000 solution)
• Chlorpheamine 10 mg
• Hydrocortisone 200 mg
• Supportive treatments

Question 8

Describe the effects of adrenaline in anaphylaxis?

Answer 8

• IM route due to peripheral vasoconstriction
• Acts within minutes
• Increases BP and reverses bronchospasm

Question 9

Describe the effects of antihistamines in anaphylaxis?

Answer 9

• Chlorphenamine
• Blocks effects of histamine on target cells

Question 10

Describe the effects of glucocorticoids in anaphylaxis?

Answer 10

• Hydrocortisone (IV)
• Reduces cytokine release
• Prevents rebound symptoms

Question 11

Describe the use of supportive treatments in anaphylaxis management?

Answer 11

• Nebulised beta2 agonists
  
  • Reverse bronchospasm
• IV fluids
  
  • Restore plasma volume
• Oxygen
  
  • Reverse hypoxia

Question 12

Read these presentations for anaphylaxis

Answer 12

Question 13

Features of anaphylaxis?

Answer 13

• Acute onset
• Urticaria
• Angio-oedema
• Flushing
• Dyspnoea, wheeze

Question 14

Describe the monitoring of a patient following anaphylaxis?

Answer 14

• Should be monitored for 24 hours after resolution of reaction
  
  • In case of second phase reactivation

Question 15

Complications of anaphylaxis?

Answer 15

• Myocardial infarction
• Recurrence of reaction

Question 16

What is the best investigation for anaphylaxis?

Answer 16

• Serum tryptase
  
  • They remain elevated 12 hours after reaction