Anaphylaxis

Question 1

Which type of hypersensitivity reaction is anaphylaxis?

Answer 1

Type 1

Question 2

What is anaphylaxis?

Answer 2

Acute, severe, life-threatening allergic reaction to pre-sensitised individuals, leading to a systemic response caused by the release of immune and inflammatory mediators from basophils and mast cells.

Question 3

What are some common examples of precipitants of anaphylaxis?

Answer 3

Penicillin, contrast media, paracetamol, eggs, fish, peanuts, strawberries.

Question 4

What are the risk factors for anaphylaxis?

Answer 4

History of allergy, atopy.

Question 5

What is this a presentation of?

Acute onset urticaria, angio-oedema, flushing, dyspnoea, wheezing, diarrhoea and vomiting. Tachycardia, hypotension.

Answer 5

Anaphylaxis

Question 6

What is the aetiology of wheal and flare?

Answer 6

1. Wheal - increased capillary permeability

2. Flare - increased vasodilation

Question 7

What is the difference between asthma attack and anaphylaxis?

Answer 7

1. Absence of allergen exposure
2. History of previous asthma attacks
3. Rapid onset suggests anaphylaxis

Question 8

What is the treatment of anaphylaxis post-emergency?

Answer 8

1. Serum tryptase (max 4h after) to confirm diagnosis (undetectable if not anaphylaxis)
2. If negative consider other causes of cardiovascular collapse.
3. May be elevated in conditions like systemic mastocytosis.

Question 9

Where should an epi-pen be administered?

Answer 9

Antero-lateral aspect of middle third of the thigh.