Anaphylaxis

Question 1

what is anaphylaxis

Answer 1

severe type 1 hypersensitivity reaction

Question 2

pathophysiology?

Answer 2

IgE stimualtes mast cells to release histamine & other pro-inflammatory chemicals

Question 3

presentation of anaphylactic reaction

Answer 3

airway, breathing and circulation compromise

• urticaria
• itching
• angio-oedema
  
  • swelling around lips and eyes
• abdo pain
• SOB
• wheeze
• tachycardia
• swelling of larynx–> stridor

Question 4

Mx?

Answer 4

Airway; secure

Breathing; give oxygen if required

Circulation; IV bolus of fluids (20ml/kg)

Disability; lie patient flat

Exposure; look for flushing, urticaria & angiooedema

Once diagnosis established:

• IM Adrenaline
• Antihistamines
• IV Hydrocortisone

Question 5

what should you do after the event?

Answer 5

• admit for observation as high chance of 2nd anaphylactic reaction
• measure serum mast cell tryptase within 6 hrs
  
  • to confirm diagnosis
• educate child & family

Question 6

long-term Mx?

Answer 6

• avoidance of allergen
• epipen

Question 7

outline the mechanism behind type 1 hypersensitivity reaction

Answer 7

IgE mediated mast cell degranulation, releasing histamine

This causes an immediate reaction

Question 8

outline the mechanism behind type 2 hypersensitivity reaction

Answer 8

IgG and IgM react to an allergen and activate complement –> direct damage to local cells

example: transfusion reaction

Question 9

outline the mechanism behind type 3 hypersensitivity reaction

Answer 9

immune complexes accumulate & cause damage to local tissues ie SLE

Question 10

outline the mechanism behind type 4 hypersensitivity reaction

Answer 10

cell mediated hypersensitivity reactions caused by inappropriate activation of T lymphocytes –> inflammation & damage to local tissues

example: organ transplant rejection