Anaphylaxis

Question 1

What type of reaction is anaphylaxis caused by?

Answer 1

A severe type 1 hypersensitivity reaction.

Question 2

What happens in a type 1 hypersensitivity reaction?

Answer 2

Immunoglobulin E (IgE) stimulates mast cells to rapidly release histamine and other pro-inflammatory chemicals (mast cell degranulation).

This causes a rapid onset of symptoms, with airway, breathing and/or circulation compromise.

Question 3

What is the key feature that differentiates anaphylaxis from a non-anaphylactic allergic reaction?

Answer 3

The compromise of the airway, breathing or circulation.

Question 4

Presentation of anaphylaxis?

Answer 4

Patients present with a history of exposure to an allergen (although it can be idiopathic).

Symptoms:
- Urticaria
- Itching
- Angio-oedema, with swelling around lips and eyes
- Abdominal pain

Additional symptoms:
- Shortness of breath
- Wheeze
- Swelling of the larynx, causing stridor
- Tachycardia
- Lightheadedness
- Collapse

Question 5

Management of anaphylaxis?

Answer 5

ABCDDE approach.

Once a diagnosis of anaphylaxis is established, there are three medications given to treat the reaction:

1) IM adrenaline

2) Antihistamines e.g. oral chlorphenamine or cetirizine

3) Steroids: usually IV hydrocortisone

Question 6

What 3 medications are indicated in anaphylaxis?

Answer 6

1) IM adrenaline

2) Antihistamines, such as oral chlorphenamine or cetirizine

3) Steroids

Question 7

What steroid is typically given in anaphylaxis?

Answer 7

IV hydrocortisone

Question 8

What dose adrenaline is given in anaphylaxis?

Answer 8

IM adrenaline (1:1000) 0.50ml

Question 9

When can administration of adrenaline be repeated in anaphylaxis?

Answer 9

Repeat administration every 5 minutes if the patient remains haemodynamically unstable (max 5mL).

Question 10

Recommended site for adrenaline injection in anaphylaxis?

Answer 10

he anterolateral aspect of the middle third of the thigh.T

Question 11

If the patient remains haemodynamically unstable after 2 doses of adrenaline, what is then indicated?

Answer 11

Then an adrenaline infusion may be required (this will be a consultant/critical care led decision).

Question 12

Overview of management of anaphylaxis

Answer 12

A - Secure airway

B - Can give nebulised bronchodilators if there is suspicion of bronchospasm (e.g. wheezing on auscultation)

C - IM adrenaline, IV fluids

D

E - antihistamines, allergen removal

Question 13

What fluids are indicated in anaphylaxis?

Answer 13

Patients with anaphylaxis require urgent fluid resuscitation:

1) Administer an initial bolus of 500-1000ml Hartmann’s solution or 0.9% sodium chloride over less than 15 mins.

2) Re-assess the patient after each fluid bolus and administer further boluses as required (large volumes of fluid may be required in the context of anaphylaxis).2

Question 14

What is refractory anaphylaxis?

Answer 14

Defined as respiratory and/or cardiovascular problems persist despite 2 doses of IM adrenaline.

Question 15

Management of refractory anaphylaxis?

Answer 15

1) IV fluids should be given for shock

2) Expert help should be sought for consideration of an IV adrenaline infusion

Question 16

Which antihistamines are indicated in anaphylaxis?

Answer 16

Non-sedating oral antihistamines (e.g. cetirizine) can be used to treat skin symptoms once the patient has been stabilised.

Question 17

What can be given in anaphylaxis following initial stabilisation especially in patients with persisting skin symptoms (urticaria and/or angioedema)?

Answer 17

Non-sedating antihistamines e.g. cetirizine (i.e. NOT chlorphenamine)

Question 18

What blood test can be done in anaphylaxis?

Answer 18

Serum tryptase

Question 19

Purpose of serum tryptase test in anaphylaxis?

Answer 19

Can help establish severity of anaphylaxis.

Question 20

All children should have a period of assessment and observation after an anaphylactic reaction, as biphasic reactions can occur.

What are biphasic reactions?

Answer 20

They can have a second anaphylactic reaction after successful treatment of the first.

Question 21

How can anaphylaxis be confirmed?

Answer 21

Anaphylaxis can be confirmed by measuring the serum mast cell tryptase within 6 hours of the event.

Question 22

What is tryptase?

Answer 22

Tryptase is released during mast cell degranulation and stays in the blood for 6 hours before gradually disappearing.

Question 23

How long after an anaphylactic reaction must tryptase be measured?

Answer 23

Within 6 hours

Question 24

What are all children and adolescents with anaphylactic reactions given?

Answer 24

Adrenalin auto-injector devices e.g. Epipen, Jext and Emerade

Question 25

Adrenalin auto-injector devices may also be considered n children with generalised allergic reactions (without anaphylaxis) with certain risk factors.

What risk factors?

Answer 25

1) Asthma requiring inhaled steroids

2) Poor access to medical treatment (e.g. rural locations)

3) Adolescents, who are at higher risk

4) Nut or insect sting allergies are higher risk

5) Significant co-morbidities, such as CVS disease

Question 26

How many adrenaline auto-injectors should patients be prescribed?

Answer 26

2

Question 27

How is an adrenaline auto-injector used?

Answer 27

1) Confirm diagnosis of anaphylaxis

2) Prepare the device by removing the safety cap on the non-needle end.

3) Grip the device in a fist with the needle end pointing downwards.

4) Administer the injection by firmly jabbing the device into the outer portion of the mid thigh until the device clicks. This can be done through clothing/

5) EpiPen advise holding it in place for 3 seconds and Jext advise 10 seconds before removing the device.

6) Remove the device and gently massage the area for 10 seconds.

7) Phone an emergency ambulance. A second dose may be given (with a new pen) after 5 minutes if required.

Question 28

When can discharge be considered in anaphylaxis in patients who have a good response to a single dose of adrenaline with complete resolution of symptoms?

Answer 28

after 2 hours of symptom resolution

as long as has been given an adrenaline auto-injector and trained how to use it

Question 29

When can discharge be considered in anaphylaxis in patients who needed 2 doses of IM adrenaline, or have had a previous biphasic reaction?

Answer 29

Minimum 6 hours after symptom resolution

Question 30

When can discharge be considered in anaphylaxis in patients who had a severe reaction needing > 2 doses of IM adrenaline?

Answer 30

minimum 12 hours after symptom resolution

Question 31

When can discharge be considered in anaphylaxis in patients who have severe asthma?

Answer 31

minimum 12 hours after symptom resolution

Question 32

When can discharge be considered in anaphylaxis in patients who present late at night?

Answer 32

minimum 12 hours after symptom resolution