Anaphylaxis

Question 1

What is the definition of anaphylaxis?

Answer 1

severe, life-thretening, generalised or systemic hypersensitivity reaction

Question 2

What is anaphylactic shock?

Answer 2

rapid onset Type 1 IgE-mediated hypersensitivity reaction that develops when a patient is exposed to certain precipitants

is a life-threatening medical emergency

Question 3

What are 3 common precipitants of anaphylaxis?

Answer 3

1. Food - nuts, egg
2. Drugs
3. Venom - insect stings e.g. wasp

Question 4

What are 6 clinical features of anaphylaxis?

Answer 4

1. Generalised pruritus, widespread erythematous or urticarial rash
2. Swelling of throat and tongue - can cause hoarse voice, stridor
3. Respiratory wheee, dyspnoea
4. GI symptoms: abdominal pain, nausea, vomiting, diarrhoea
5. Hypotension (faint, dizziness, collapse)
6. Tachycardia

Question 5

What are the 8 stages of management of anaphylaxis?

Answer 5

1. Remove trigger if possible
2. Call for help early
3. ABCDE assessment
4. Administer oxygen
5. Lie patient flat and raise legs
6. Administer adrenaline
7. Administer chlorphenamine and hydrocortisone
8. IV fluid challenge if hypotensive

Question 6

What is the adult dose of adrenaline in anaphylaxis?

Answer 6

500 micrograms - aka 0.5ml of 1:1000 adrenaline

Question 7

What is the adult dose of hydrocortisone for anaphylaxis?

Answer 7

200mg

Question 8

What is the adult dose of chlorphenamine for anaphylaxis?

Answer 8

10mg

Question 9

What are the paediatric doses of adrenaline in anaphylaxis for <6 months, 6 months - 6 years, and 6 - 12 years?

Answer 9

• <6 months: 150 microcrams (0.15ml 1 in 1000)
• 6 months - 6 years: 150 micrograms
• 6-12 years: 300 micrograms

Question 10

When can the adrenaline dose be repeated?

Answer 10

every 5 minutes if necessary

Question 11

What is the best site for IM injection of adrenaline?

Answer 11

anterolateral aspect of the middle third of the thigh

Question 12

For how long should patients who have had emergency treatment for anaphylaxis be observed and why?

Answer 12

for 6-12 hours from onset of symptoms, as it is known biphasic reactions can occur in up to 20% of patients

Question 13

What blood test should be measured in patients with suspected anaphylaxis and why?

Answer 13

mast cell tryptase - sometimes difficult to establish whether true episode of anaphylaxis. this will be elevated for up to 12 hours following acute anaphylaxis

Question 14

What is the best time to measure serum tryptase?

Answer 14

1-2 hours (but no longer than 4 hours) after symptoms begin