CTB8: Anaphylaxis: a cardiovascular-respiratory problem Flashcards
To who does anaphylaxis occur most frequently?
Young people and women
What is anaphylaxis?
Severe allergic reaction
What are the 5 signs of acute inflammation? Explain them
Rubor – redness from vasodilation in the skin
Calor – heat from vasodilation in the skin
Tumor – swelling from plasma exudation into tissues
Dolor – pain and unpleasant sensation from sensory nerve activation
(Functio laesa) – loss or disturbance of function
Other than the 5 signs of acute inflammation, what else characterises anaphylaxis?
Rapid onset, itching, rhinitis and conjunctivitis, nausea, and hypotension. It is generally treated by administering adrenaline by injection.
What acts as an allergen that can trigger anaphylaxis?
Serval antigens found in food, venom and drugs. However, , many anaphylaxis cases are idiopathic and have no identifiable cause
What is an anaphylactic reaction to antigens called?
Type I hyper-sensitivity (caused by an inappropriate IgE response)
How is type I hypersensitivity caused?
An inappropriate IgE response. The antigen binds to the B lymphocyte and stimulates IgM antibody secretion which usually switches to IgG. However, in this case, CD4+ T cell activation causes a switch to IgE production which is long-term and sensitises individuals for long periods
What can IgEs bind to?
high-affinity receptors (FCeRI) on the surface of mast cells and basophils
What do mast cells and basophils contain?
What happens to these upon IgE binding?
Granules of inflammatory mediators including histamine and products of arachidonic acid metabolism that are secreted upon IgE binding, if two IgE molecules on FCeRI are cross-linked
What do inflammatory mediators act upon?
vascular and non-vascular smooth muscle
Where does histamine cause vasodilation?
At the surface and non-dermal vascular beds and oedema which cause hypotension.
Describe 1-4 hypersensitivity
Type I: immediate-type, anaphylactic reactions (immunoglobulin E, IgE antibodies)
Type II: cytolytic reactions – autoimmune, IgG and IgM, targets vascular cells (haemolytic anaemia)
Type III: complement fixation – induces inflammation, IgG
Type IV: delayed-type (sensitised T-lymphocytes – inflammation)
What do inflammatory mediators around the mucosae do?
Contract airways and contract smooth muscle
What is the ABC treatment for anaphylaxis?
A) Airways
B) Breathing
C) Circulation
What does initial therapy for anaphylaxis intend to do?
open up narrowed airways to reverse bronchoconstriction and elevate blood pressure to restore tissue perfusion.
