Anaphylaxis

Question 1

What is anaphylaxis, and why is it considered a medical emergency?

Answer 1

Anaphylaxis is a life-threatening medical emergency caused by a severe type 1 hypersensitivity reaction. It involves the rapid release of histamine and other pro-inflammatory chemicals, leading to airway, breathing, and/or circulation compromise.

Question 2

What immune mechanism underlies anaphylaxis?

Answer 2

Anaphylaxis is triggered by immunoglobulin E (IgE), which stimulates mast cells to release histamine and other pro-inflammatory chemicals in a process called mast cell degranulation.

Question 3

How does anaphylaxis differ from a non-anaphylactic allergic reaction?

Answer 3

The key feature that differentiates anaphylaxis from a non-anaphylactic allergic reaction is the compromise of the airway, breathing, or circulation. Non-anaphylactic allergic reactions do not typically involve these severe systemic effects.

Question 4

What are common symptoms of anaphylaxis following exposure to an allergen?

Answer 4

Common symptoms include urticaria, itching, angio-oedema (swelling around the lips and eyes), and abdominal pain. Additional symptoms indicating anaphylaxis include shortness of breath, wheezing, laryngeal swelling (causing stridor), tachycardia, lightheadedness, and collapse.

Question 5

What should be the initial approach to assessing a patient suspected of anaphylaxis?

Answer 5

The initial assessment follows the ABCDE approach:
A (Airway): Secure the airway.
B (Breathing): Provide oxygen if needed; use salbutamol for wheezing.
C (Circulation): Administer an IV bolus of fluids.
D (Disability): Lay the patient flat to improve cerebral perfusion.
E (Exposure): Examine for flushing, urticaria, and angio-oedema.

Question 6

Besides adrenaline, what other medications are used in the management of anaphylaxis?

Answer 6

In addition to adrenaline, antihistamines (such as oral chlorphenamine or cetirizine) and steroids (usually intravenous hydrocortisone) are used to manage anaphylaxis.

Question 7

What is the first-line medication for treating anaphylaxis, and how often can it be administered?

Answer 7

The first-line medication is intramuscular adrenaline, which can be repeated after 5 minutes if necessary.

Question 8

Why is it important to call for help early when managing anaphylaxis?

Answer 8

Anaphylaxis is a life-threatening emergency that requires prompt and experienced medical intervention to prevent rapid deterioration, making early help crucial.

Question 9

Why should children be observed after an anaphylactic reaction, and where should they be admitted for observation?

Answer 9

Children should be observed after an anaphylactic reaction due to the risk of a biphasic reaction, where a second anaphylactic reaction can occur after the initial treatment. They should be admitted to the paediatric unit for observation.

Question 10

How can an anaphylactic reaction be confirmed after the event?

Answer 10

Anaphylaxis can be confirmed by measuring serum mast cell tryptase within 6 hours of the event. Tryptase is released during mast cell degranulation and remains in the blood for about 6 hours before gradually disappearing.

Question 11

What are the key components of education and follow-up for a child and their family after an anaphylactic event?

Answer 11

Education should cover allergy awareness, avoiding allergens, recognizing the signs of anaphylaxis, and training in basic life support. The family should also receive training on how to use an adrenaline auto-injector. Referral to a specialist is necessary for diagnosis, education, follow-up, and training.

Question 12

When should mast cell tryptase be measured in a patient who has had an anaphylactic reaction, and why is this important?

Answer 12

Mast cell tryptase should be measured within 6 hours of an anaphylactic reaction. This measurement is crucial for confirming the diagnosis of anaphylaxis and is a common exam question.

Question 13

What are the indications for prescribing an adrenaline auto-injector (e.g., Epipen, Jext, Emerade) to children and adolescents?

Answer 13

Adrenaline auto-injectors are indicated for all children and adolescents who have had an anaphylactic reaction. They may also be considered for children with generalized allergic reactions who have risk factors such as:
- Asthma requiring inhaled steroids
- Poor access to medical treatment (e.g., rural areas)
- Adolescence, as this group is at higher risk
- Nut or insect sting allergies
- Significant comorbidities, such as cardiovascular disease

Question 14

What is the first step before using an adrenaline auto-injector?

Answer 14

The first step is to confirm the diagnosis of anaphylaxis.

Question 15

How do you prepare the adrenaline auto-injector for use?

Answer 15

Prepare the device by removing the safety cap on the non-needle end. For an EpiPen, remove the blue cap, and for a Jext, remove the yellow cap. ‘‘Orange to thigh; blue to sky’’

Question 16

How should the adrenaline auto-injector be held, and why is it important not to place your thumb over the end?

Answer 16

The device should be gripped in a fist with the needle end pointing downwards (orange on EpiPen and black on Jext). It is important not to place your thumb over the end because if the device is upside down, you could accidentally inject adrenaline into your thumb, which may result in serious injury.

Question 17

Where and how should the adrenaline auto-injector be administered?

Answer 17

The injection should be administered by firmly jabbing the device into the outer portion of the mid-thigh until the device clicks. This can be done through clothing. Hold the EpiPen in place for 3 seconds and the Jext for 10 seconds before removing the device.

Question 18

What steps should be taken after administering the adrenaline injection?

Answer 18

After administering the injection, remove the device and gently massage the injection area for 10 seconds. Then, phone an emergency ambulance. If needed, a second dose may be given with a new pen after 5 minutes.

Question 19

Why is it important to familiarize yourself with adrenaline auto-injector devices like EpiPen and Jext?

Answer 19

It is important to familiarize yourself with these devices because you may be asked to demonstrate their use to a parent or child in exams or clinical practice. Practicing with dummy devices can help you explain and perform the procedure confidently.