anaphylaxis

Last reviewed 10/2021

• anaphylactic shock is a medical emergency; it is a life- threatening type I hypersensitivity reaction.
• there is no single definition.
  • generally describesd as a severe, life-threatening, generalised or systemic hypersensitivity reaction.(1)
    
• the main characteristics are rapidly developing life-threatening circulatory collapse and airway impairment in response to an allergen to which the patient has previously been sensitized.Usually skin and mucosal changes are associated.

In the UK it is estimated that 500,000 people have had a venom-induced anaphylactic reaction and 220,000 people up to the age of 44 have had a nut-induced anaphylactic reaction (2)

• available UK estimates suggest that approximately 1 in 1333 of the population of England has experienced anaphylaxis at some point in their lives
• there are approximately 20 deaths from anaphylaxis reported each year in the UK, with around half the deaths being iatrogenic, although this may be an underestimate

Reference:

• (1) Emergency treatment of anaphylactic reactions.Guidelines for healthcare providers.Working Group of the Resuscitation Council (UK).2008
• (2) NICE (December 2011). Anaphylaxis: assessment to confirm an anaphylactic episode and the decision to refer after emergency treatment for a suspected anaphylactic episode.