General: Allergy and Anaphylaxis

Question 1

Outline the pathophysiology of allergy and anaphylaxis.

Answer 1

Ag first exposure —> activates B cell —> prod IgE —> binds mast cell

Re-exposure to Ag —> this bridges IgE —> mast cell degranulation —> histamine release —> increased permeability of capillaries —> tissue swelling —> airway inflam

Question 2

Outline the aetiology of allergy and anaphylaxis

Answer 2

Idiopathic = 61%

Nuts

Drugs - 5 mins to CA

Latex

Question 3

What are the signs and symptoms of allergy and anaphylaxis?

Answer 3

Wheeze = whistling sound mainly on expiration

Urticaria = raised rash (hives)

Flush

Hypotension

Peri-orbital oedema

Question 4

How would you investigate allergy?

Answer 4

Skin pick testing

Bloods = Abs

Patch test = investigates contact dermatitis

Elimination diet

Challenge testing = given a small amount of food, in increasing amount, observed under close supervision

Question 5

How would you manage allergy and anaphylaxis?

Answer 5

A-E assessment = high flow O2, secure airway

IM adrenaline 0.5 mg - repeat every 5 mins as needed to support CVS

IV hydrocortisone 200mg

IV chlorpheniramine 10 mg

Hypotensive = lie flat and fluid resuscitate

Bronchospasm = neb salbutamol (± IV aminophylline)

Laryngeal oedema = neb adrenaline

Question 6

How would you monitor a pt after an anaphylactic episode?

Answer 6

Observe overnight

Continue oral antihistamine

Continue oral prednisolone 30-40mg 48 hours

Question 7

What are the complications of allergy and anaphylaxis?

Answer 7

Partial/complete airway obstruction

Hypotension = shock

Fluid build up in the lungs

Death