Anaphylaxis

Question 1

Define Anaphylaxis

Answer 1

Acute life-threatening multisystem syndrome caused by sudden release of mast cell and basophil-derived mediators into circulation

Question 2

Explain the Aetiology of Anaphylaxis

Answer 2

• Immunogenic: IgE mediated or immune complex/complement-mediated
• Non-immunogenic: mast cells or basophil degranulation without the involvement of antibodies (e.g. reactions caused by vancomyocin, codeine, ACE inhibitor)
• Pathophysiology: Inflammatory mediators such as histamine are released leading to bronchospasm, increased capillary permeability and reduce vascular tone ==> tissue oedema

Question 3

List some common Allergens

Answer 3

• Drugs (e.g. penicillin)
• Latex
• Peanuts
• Shellfish
  Note: anaphylaxis can be caused by repeat administration of blood products in a patient with selective IgA deficiency (anti-IgA antibodies formed)

Question 4

What is the epidemiology of Anaphylaxis?

Answer 4

Common

0.5-1% children allergic to peanuts

Question 5

What are the Risk factors for Anaphylaxis?

Answer 5

• History of asthma/atopy
• Exposure to common sensitiser
• Previous anaphylaxis reaction

Question 6

What are the Symptoms of Anaphylaxis?

Answer 6

• Wheeze
• Shortness of breath and sense of choking
• Swelling of lips and face
• Pruritus
• Rash
  Note: patients may have a history of other hypersensitivy reactions (e.g. asthma, allergic rhinitis)

Question 7

What are the Signs of Anaphylaxis?

Answer 7

• Tachypnoea
• Wheexe
• Cyanosis
• Swollen upper airways and eyes
• Rhinitis
• Conjuctival infection
• Urticarial rash
• Hypotension
• Tachycardia

Question 8

Identify the appropriate investigations for Anaphylaxis

Answer 8

• Clinical diagnosis
• Serum tryptase, histamine levels or urinary metabolites of histamine may help support the clinical diagnosis
• Following in attack:
• allergen skin testing (identifies allergen)
• IgE immunoassays (identifies food-specific IgE in the serum)

Question 9

What is the Management plan for Anaphylaxis

Answer 9

• ABCDE
• High flow oxygen
• IM Adrenaline
• Chlorpheniramine (antihistamine)
• Hydrocortisone
• If continued respiratory deterioration, may required bronchodilator therapy
• Monitor pulse oximetry, ECG and BP
• Shock position (legs raised)

Question 10

Identify the possible complications of anaphylaxis and its management

Answer 10

• Shock and organ damage as a result

- Manage with fluids and monitor

Question 11

Summarise the prognosis

Answer 11

• Good with prompt treatment