Anaphylaxis

Question 1

What are the life-threatening ABC problems associated with anaphylaxis?

Answer 1

Airway:
Hoarse voice
Stridor

Breathing:
Increased WoB
Wheeze
Fatigue
Cyanosis
SpO2<94

Circulation:
Low blood pressure
Signs of shock
Reduced consciousness

Question 2

How much fluid is indicated for anaphylaxis?

Answer 2

500-1000ml rapid bolus

Question 3

What is the adult dose for ADM for anaphylaxis?

Answer 3

500 micrograms IM (0.5ml)

Question 4

When would you administer adrenaline straight away for anaphylaxis?

Answer 4

In the presence of any life threatening signs:

Altered consciousness level
Exhaustion
Cyanosis
Silent chest
Poor respiratory effort
PEF <33%
SpO2 <92%
Arrythmia
Hypotension

Question 5

What is the treatment of choice for mild and moderate allergic reactions?

Answer 5

Oral anti-histamines

Question 6

What is the dose interval for ADM for anaphylaxis?

Answer 6

5 minutes

Question 7

What is the pathophysiology of anaphylaxis?

Answer 7

An antigen enters the body

Lymphocytes produce T cells which activate B cells.

Activated B cells produce Immunoglobin E (IgE) antibodies

IgE antibodies attach to proteins on mast cells (and basophils)

These produce histamine and inflammatory mediators (cytokines)

Histamine increases smooth contraction in the bronchioles (leading to bronchoconstriction) and is a natural vasodilator.

Combined with cytokines, it also increases vascular permeability.

This leads the body to go into shock as fluid leaks out into the interstitial space of cells

Question 8

Why is chlorphenamine not the priority in anaphylaxis?

Answer 8

Although it prevents histamine having further effects it does not reverse any effects already occuring

Question 9

How does hydrocortisone help with allergic reactions?

Answer 9

It’s a glucocorticoid steroid that reduces inflammation by downregulation of the inflammatory response - it reduces the number of receptors available for the inflammatory response to have an effect

It also increases the β2 receptors available by upregulation – increasing the amount of these receptors available in the lungs

Question 10

How does hydrocortisone increase the effectiveness of salbutamol?

Answer 10

It increases the β2 receptors available by upregulation – increasing the amount of these receptors available in the lungs