Dermatology/Allergy: Anaphylaxis

Question 1

What is anaphylaxis

Answer 1

A sudden, severe and systemic reaction with involvement of airway, breathing or circulation

• Sudden: generally within 30minutes (usually 5 mins for IV)
• Systemic: i.e. not just a skin reation

Question 2

What is Kounis syndrome

Answer 2

Anaphylaxis can cause myocardial dysfunction and ischaemia leading to MI (STEMI)

Question 3

How to manage anaphylaxis

Answer 3

1) Before anything, STOP the offending agent
2) IM adrenaline 500mcg (0.5ml of 1:1,000)
- Repeat adrenaline after 5 minutes
3) Airway, Oxygen
4) IV fluids (do not flush through the same cannula that was running the offending agent)

Question 4

Where to inject adrenaline in anaphylaxis

Answer 4

Middle third of the thigh

Anterolateral

Question 5

How to position a patient with anaphylaxis

Answer 5

Lying if low BP (consider legs elevated)
Although sometimes sitting will help breathing
If pregnant, lie on left side (this prevents compression of the IVC)

Question 6

What are the doses of IM adrenaline (by age)

Answer 6

> 12 years: 500mcg (0.5ml)
6-12 years: 300mcg (0.3ml)
6m - 6y: 150mcg (0.15ml)
<6m: 100-150mcg

Question 7

What other symptoms may occur in anaphylaxis

Answer 7

Can get abdo pain and GI symptoms due to fluid shift in the GI tract

Question 8

What is the next step if 2 doses of IM adrenaline have not worked

Answer 8

Call for help. May need intubation
Start an IV adrenaline infusion
Keep giving IM every 5 mins until infusion gets started

Dose of IV infusion:
Draw up 1mg Adrenaline in 100ml of saline
Infuse 0.5-1ml / kg /hr
Titrate according to response

Question 9

Notes on setting up an IV adrenaline infusion

Answer 9

1mg adrenaline in 100ml saline
It must be done via a dedicated line (i.e. not mixed)
Do not do it on the same side as BP cuff - will interfere with circulation
Pt needs to be observed on monitor troughout

Question 10

How to detect adrenaline overdose when infusing

Answer 10

Highly raised BP

Question 11

What to do after treating anaphylaxis

Answer 11

Observe for 6-12 hours
This is due to the risk of ‘biphasic reaction’ which can occur in 20% of patients

Do they need an alert bracelet?
They need an epipen x2 and showing how to use it
They need referral to allergist

Question 12

When to measure mast cell tryptase

Answer 12

Take 1st sample immediately

2nd sample after 1-2 hours (not more than 4 hours)

Question 13

Other treatments after initial resuscitation and adrenaline

Answer 13

IV chlorphenamine (10mg adult)
IV hydrocortisone (200mg adult)
Consider nebulized adrenaline or salbutamol/ipratropium if wheeze