ILA anaphylaxis

Question 1

define anaphylaxis

Answer 1

A severe, life-threatening, generalised or systemic hypersensitivity reaction.
It is characterised by rapidly developing life-threatening airway and/or breathing and/or circulation problems usually associated with skin and mucosal changes

Question 2

state the signs and symptoms of anaphylaxis

Answer 2

vasodilation, increased vascular permeability, bronchoconstriction, urticaria, angio-oedema

Question 3

list the possible trigger agents for anaphylaxis encountered in the community

Answer 3

bee stings, nuts, milk, shellfish, fruit

Question 4

list the possible trigger agents for anaphylaxis encountered in a hospital setting

Answer 4

medicines (e.g. antibiotics, NSAIDs), latex, general anaesthesia, contrast agents (e.g. dyes)

Question 5

describe the pathophysiology of the heart rate and BP in anaphylaxis

Answer 5

massive vasodilation of blood vessels as an inflammatory response - decrease in BP, increase in heart rate

Question 6

describe the pathophysiology of low O2 sats and wheezing

Answer 6

mast cells and basophils release histamine which constricts the smooth muscles of airways.
swollen upper airway, bronchi and bronchioles, slightly oedematous in their inflammatory response

Question 7

describe the pathophysiology of urticaria

Answer 7

swelling/redness/soreness from mast cells releasing histamine and other immunomodulators as an inflammatory response and fluid leaking out of the blood vessels into the dermis

Question 8

describe the pathophysiology of first exposure to anaphalactic triggers

Answer 8

• t cell is activated by cytokines and antigen presenting cells
• b cell stimulated to produce IgE antibodies -> causes mast cells and basophils to produce pro-inflammatory molecules = degranulation

Question 9

describe the pathophysiology of second exposure to anaphalactic triggers

Answer 9

• mast cells and basophils bind to antigen and release pro-inflammatory molecules immediately
• these leak into blood streak and affect multiple organs

Question 10

describe the treatment for anaphylaxis

Answer 10

IM adrenaline, H1 receptor oxygen

Question 11

explain the pharmacological action of adrenaline on beta receptors

Answer 11

• beta1 adrenoceptors: positive ionotrophic effects on heart
• beta2 adrenoceptors: reduces oedema and bronchodilates

Question 12

explain the pharmacological action of adrenaline on alpha receptors

Answer 12

• alpha1 adrenoceptors: peripheral vasoconstriction, increase in peripheral vascular resistance, increased BP and coronary perfusion

Question 13

how does adrenaline increasing intracellular cAMP help treat anaphylaxis?

Answer 13

no more mediators from mast cells and basophils and reduced release on inflammatory mediators

Question 14

why might you need two doses of adrenaline in the treatment of anaphylaxis?

Answer 14

short half life - second dose may be required if the symptoms do not initially respond or get worse. An infusion may be required in refractory anaphylaxis

Question 15

what type of hypersensitivity is anaphylaxis and what immunoglobin is it?

Answer 15

type 1, IgE

Question 16

what are the actions of histamine?

Answer 16

1. smooth muscle contraction in bronchi and GI tract
   -> tougher for air and food to get through
2. blood vessel dilation and increased permeability
   -> swelling, oedema

Question 17

What affect do cytokines interlukin-4 and interlukin-13 have on B-cells?

Answer 17

Production of more IgE antibodies and TNF,
Synthesis of leukotriene (attracts immune cells to the location)

Question 18

Which receptors cause increased HR?

Answer 18

beta 1 - positive ionotropic and chronotropic

Question 19

what is the ideal time to perform a tryptase test?

Answer 19

1-2 hours after onset of symptoms