Anaphylaxis

Question 1

Define anaphylaxis.

Answer 1

Multisystem allergic reaction characterised by:
(1) Acute onset illness with typical skin features
PLUS
(2) Involvement of respiratory and/or cardiovascular symptoms and/or persistent GI symptoms

OR

Any acute onset hypotension or upper airway obstruction where anaphylaxis is considered possible even without skin features.

Question 2

What is the immediate management of anaphylaxis?

Answer 2

10 mcg/kg or 0.01 ml/kg of 1:1000 (max 0.5 ml) into lateral thigh. Repeat after 5 mins if no improvement.

Question 3

What are possible risk factors for fatal anaphylaxis?

Answer 3

Adolescence, nut/shellfish allergy, poorly controlled asthma, delays to emergency services/adrenaline, pre-existing cardiac/respiratory conditions

Question 4

What sort of time frame do most anaphylactic reactions occur in?

Answer 4

30 mins. Can occur up to 4 hours post-exposure.

Question 5

List features of anaphylaxis.

Answer 5

Respiratory: cough, wheeze, tongue swelling, stridor, hoarse voice, throat tightness, dysphagia.
CVS: pale/floppy, palpitations, tachy, brady, hypotension, collapse +/- LOC, arrest.
Neuro: headache, dizziness, ALOC/confusion.
GI: nausea/vomiting, diarrhoea, abdo pain
Derm: urticaria, erythema, flushing or angio-oedema

Question 6

What are the autoinjectors available for anaphylaxis in children?

Answer 6

10-20 kg (~1-5 years old) = 0.15 mg = green label

> 20 kg (>5 years) = 0.3 mg = yellow label

Question 7

How do you manage an adrenaline infusion in children?

Answer 7

Mix 1 ml of 1:1000 adrenaline in 1000 ml of normal saline. Start the infusion at 5 ml/kg/hr (~0.1 mcg/kg/min)

Question 8

List the other treatments that can be considered with paediatric anaphylaxis in addition to adrenaline.

Answer 8

Salbutamol: especially if has a hx of asthma, is wheezing
Antihistamines: symptomatic relief of pruritus

Question 9

What antihistamine should be avoided in anaphylaxis?

Answer 9

Promethazine; it causes hypotension.

Trial of a second generation.

Question 10

What children should be admitted and for how long after anaphylaxis?

Answer 10

Minimum of 12 hours if: (a) need further treatment within 4 hours of last adrenaline administration, (b) previous hx of biphasic reaction, (c) poorly controlled asthma, (d) socially/geographically isolated family

Question 11

What is the dose of adrenaline in a cardiac arrest situation?

Answer 11

10 mcg/kg = 0.1 ml/kg of 1:10,000 solution