Allergy

Question 1

What is anaphylaxis? What causes it

Answer 1

It is a life threatening medical emergency caused by a severe type 1 hypersensitivity reaction

IgE stimulates mast cells to degranulate, releasing histamine and pro-inflammatory cytokines
Causes airway, breathing and/or circulation compromise

Question 2

What differentiates anaphylaxis from a non-anaphylaxis allergic reaction

Answer 2

Compromise of airway, breathing or circulation

Question 3

Presentation of anaphylaxis

Answer 3

Airway:
Swelling of tongue and throat = hoarse voice, stridor

Breathing: wheeze, dyspnoea

Circulation: hypotension, tachycardia
Lightheadedness, collapse

Generalised itchiness
Widespread erythema or urticaria
Abdominal symptoms

Question 4

Common causes of anaphylaxis

Answer 4

Food e.g. nuts
Drugs
Venom e.g. bee, wasp

Question 5

Guidelines for anaphylaxis

Answer 5

Confirm it’s anaphylaxis
Call for help
Remove trigger e.g. infusion, lie flat with legs raised or not, some patients might find breathing easier if seated upright

IM Adrenaline
- give oxygen if hypoxic
- monitor oxygen says, BP, ECG for response

If no response: repeat IM adrenaline after 5 mins
IV fluid bolus

If no improvement in breathing/circulation despite 2 doses: refractory anaphylaxis algorithm

Question 6

What is part of the refractory anaphylaxis algorithm

Answer 6

Rapid IV fluid bolts (hypotension and shock)
Give oxygen, continue monitoring
Take blood sample for mast cell tryptase

Seek expert help for IV adrenaline infusion
Peripheral low dose IV adrenaline infusion: 0.5-1ml/kg/hr for adults and children, titrate according to response

*** INCREASED BP likely to indicate adrenaline overdose

Question 7

When to measure mast cell tryptase levels

Answer 7

A sample as soon as possible after emergency treatment has started

Second sample ideally within 1-2 hours, but no later than 4, from onset of symptoms

Might need a baseline sample later

**start decreasing after 6 hours following event

Question 8

Management following stabilisation in anaphylaxis

Answer 8

Non sedating oral antihistamines = persisting skin symptoms e.g. urticaria, angioedema

All patients with a new diagnosis should be referred to the allergy clinic & adrenaline injector given for the interim (2 adrenaline autoinjectors)