ANAPHYLAXIS

Question 1

Most common precipitants of anaphylaxis?

Answer 1

Foods in children - nuts, shellfish
Drugs
Venom e.g. wasp sting

Question 2

Time to anaphylaxis?

Answer 2

20 mins - 2 hours after exposure

Question 3

Risk factors for anaphylaxis?

Answer 3

Atrophy - asthma, hay fever, eczema

Question 4

Cofactors for anaphylaxis?

Answer 4

Exercise
NSAIDs
Alcohol
Sleep deprivation
Stress
Infection

Question 5

Pathophysiology of anaphylaxis?

Answer 5

Type 1 hypersensitivity reaction

Sensitisation phase: the immune system encounters allergen and makes IgE against it but no clinical features
Effector phase: allergen cross-links IgE on the surface of mast cells causing widespread degranulation and release of histamine which mediates inflammatory bronchospasm, vasodilatation, increased capillary permeability and tissue oedema

Question 6

What scoring system is used for anaphylaxis?

Answer 6

Ring and Messmer

Question 7

Outline the ring and messmer scorng system for anaphylaxis?

Answer 7

Grade 1 - generalised cutaneous signs - erythema, urticaria, angioedema
Grade 2 - non-life threatening multivisceral involvement with cutaneous signs, hypotension, tachycardia and bronchial hyperreactivity
Grade 3 - severe life threatening - collapse, tachy/bradycardia, arrhythmias, bronchospasm
Grade 4 - cardiac or respiratory arrest

Question 8

Clinical presentation of anaphylaxis?

Answer 8

A-> swelling of throat and tongue, sensation throat is closing up, stridor and hoarse voice
B -> wheeze, increased RR, dyspnoea, confusion from hypoxia, cyanosis, resp arrest
C -> pale, clammy, hypotension and tachycardia. Can cause cardiac arrest if not dealt with very quickly!
D -> feeling generally unwell, anxious and have a sense of impending doom. May have decreased conscious level by an ABC issues
E -> 80-90% also have skin and mucosal changes e.g. generalise pruritus, angioedema, widespread erythematous or urticaria rash

Question 9

Criteria for anaphylaxis being likely?

Answer 9

Sudden onset and rapid progression of symptms
Life threatening ABC problems
Skin or mucosal changes
Known allergen

Question 10

What investigation can you do to confirm an anaphylaxis reaction?

Answer 10

3 samples of mast cell tryptase: immediately, 1-2 hours after, 24 hours after

Question 11

Management of anaphylaxis?

Answer 11

Call for help - anaesthetist may be necessary
Remove trigger
Lie pt flat with legs elevated
IM adrenaline. Repeat every 5 minutes if necessary.
Establish airway, give high flow oxygen and apply monitoring
IV fluid bolus

Non-sedating oral antihistamine if persisting skin symptoms
Refer to a specialist allergy clinic and give an adrenaline injector

Question 12

Doses of adrenaline for anaphylaxis?

Answer 12

0.5ml 1 in 1000 for adults and children >12
0.3 ml if 6-12
0.15ml if 6 months-6 years
0.1ml if <6 months

Question 13

What is a biphasic anaphylaxis?

Answer 13

the recurrence of anaphylaxis symptoms within 72 hours of the initial anaphylactic event, without re-exposure to the trigger.

Question 14

How commonly do biphasic anaphylactic reactions occur?

Answer 14

In up to 20% of cases

Question 15

Who can have a fast track discharge i.e. after 2 hours of symptoms resolution?

Answer 15

Those that…
Good response to a single dose of adrenaline
Complete resolution of symptoms
Has been given an adrenaline auto-injector and trained how to use it
Adequate supervision following discharge

Question 16

Which patients must remain in hospital for at least 6 hours after anaphylactic symptom resolution?

Answer 16

Those that required 2 doses of IM adrenaline or have had a previous biphasic reaction

Question 17

Which patients must remain in hospital for at least 12 hours after anaphylactic symptom resolution?

Answer 17

Those that had severe reactions requiring more than 2 doses of IM adrenaline
Those with severe asthma
Those who have the possibility of an ongoing reaction e.g. cause is a slow release medication
Patients presenting late at night
Patients from areas where access to emergency care may be difficult
All children

Question 18

What must patients be told about before discharge for anaphylaxis?

Answer 18

• information about anaphylaxis including signs and symptoms, risks of biphasic reactions and what to do if a reaction occurs
• Demonstration of using the Adrenalin injector and when to use it
• Advice regarding avoidance of trigger
• Information about the need for referral to the specialist allergy service and the referral process
• Infromation about pt support groups

Question 19

What is refractory anaphylaxis?

Answer 19

respiratory and/or cardiovascular problems persisting despite 2 doses of IM adrenaline.

Question 20

How is refractory anaphylaxis managed?

Answer 20

IV fluid bolus
IV adrenaline infusion - started by a specialist

If refractory to this you can consider adding a second vasopressors in addition e.g. noradrenaline, vasopressin etc
Consider glucagon if pt on a beta blocker