Anaphylaxis

Question 1

Anaphylaxis

definition

Answer 1

• a severe, life threatening, generalised and systemic hypersensitivity reaction

Question 2

Anaphylaxis

what is it?

Answer 2

• hypersensitivity reaction mediated by IgE - causing mast cell degranulation and histamine release
• histamine release produce leaky blood vessels, swelling, vasodilatation and bronchospasm
• anaphylactoid - similar reaction but not dependant on hypersensitivity. Manifestation and management similar

Question 3

Anaphylaxis

Pathophysiology

Answer 3

• Mast cells are first sensitized to an allergen in a genetically predisposed individual - more common in atopy
• Mast cells widely distributed in vascular connective tissue, especially skin, respiratory and gastrointestinal tracts
• On subsequent re-exposure, allergen binds to IgE on surface of mast cells causing release of histamine, prostaglandin D2, leukotriene C4 and TNF-a
• Increased vascular volume can result in a shift of 50% of vascular volume in 10 mins.

Question 4

Anaphylaxis

How common?

Answer 4

• No reliable data on incidents - seems to be increasingly common
• risk of recurrence after one attack 1 in 12 per year
• estimated worldwide 0,05-2% during a lifetime
• lifetime prevalence 1 in 1333

Question 5

Anaphylaxis

Causes?

Answer 5

• drugs (any - but more common with muscle relaxants, anaesthetics, NSAID, antibiotics, aspirin)
• contrast media
• food
• insect stings
• latex

Question 6

Anaphylaxis

How does it present?

Answer 6

• usually rapid onset after exposure to allergen
• reactiuons vary in severity
• progress may be rapid, slow or biphasic (in 7-20%)
• cardiovascular collapse common manifestation IV drugs / stings

Question 7

Anaphylaxis

respiratory

Answer 7

• Dyspnoea
• Rhinitis
• Rhinorrhoea
• Hoarseness
• Stridor
• Wheeze

Question 8

Anaphylaxis

Cardiovascular

Answer 8

• tachycardia
• hypotension
• Cardisc arrest

Question 9

Anaphylaxis

cutaneous

Answer 9

• urticaria
• pallor
• flushing
• angioedema

Question 10

Anaphylaxis

Gastro-intestinal

Answer 10

• nausea and vomiting
• abdominal cramps
• diarrhoea

Question 11

Anaphylaxis

neurological

Answer 11

• agitation
• apprehension
• decreasing conscious level
• feeling of impending doom

Question 12

Anaphylaxis

management

Answer 12

• remove likely allergen
• examination A/B/C/D´s
• Anaphylaxis kit/resus bag
• 999
• high flow oxygen
• epinephrine 0.5ml 1:1000 IM
• lay flat raise legs (unless respiratory symptoms predominant)
• full CPR protocol