Anaphylaxis

Anaphylaxis may be defined as a severe, life-threatening, generalised or systemic hypersensitivity reaction.

Common identified causes of anaphylaxis:

• food (e.g. nuts) - the most common cause in children
• drugs
• venom (e.g. wasp sting)

Features

The Resus Council UK define anaphylaxis as:

• the sudden onset and rapid progression of symptoms
• Airway and/or Breathing and/or Circulation problems
• Airway problems may include:
  • swelling of the throat and tongue →hoarse voice and stridor
• Breathing problems may include:
  • respiratory wheeze
  • dyspnoea
• Circulation problems may include:
  • hypotension
  • tachycardia

This means that if there are no ABC problems then the patient is technically not having anaphylaxis.

Around 80-90% of patients also have skin and mucosal changes:

• generalised pruritus
• widespread erythematous or urticarial rash

Management

Anaphylaxis is one of the few times when you would not have time to look up the dose of a medication. The Resuscitation Council guidelines on anaphylaxis have recently been updated.

Intramuscular adrenaline is by far the most important drug in anaphylaxis and should be given as soon as possible. Previously IV hydrocortisone was also recommended but the evidence base for this was poor and it was removed in the 2021 update.