Allergy and anaphylaxis

Question 1

What is allergy?

Answer 1

umbrella term for hypersensitivity of immune system to allergens

Question 2

What are allergens?

Answer 2

Proteins that immune system recognises as foreign and potentially harmful
allergic immune response

Question 3

What are antigens?

Answer 3

Proteins recognised by immune system

Question 4

Atopy

Answer 4

predisposition to having hypersensitivity reactions to allergens

Question 5

Atopy conditions

Answer 5

hayfever, eczema, asthma, allergic rhinitis and food allergies

Question 6

Type 1 hypersensitivity

Answer 6

IgE antibodies to specific allergen trigger mast cells and basophils to release histamine and cytokines
immediate eg food allergy

Question 7

Type 2 hypersensitivity

Answer 7

IgG and IgM - complement system

haemolytic disease of newborn and transfusion reactions

Question 8

Type 3 hypersensitivity

Answer 8

Immune complexes accumulate and cause damage to local tissues eg SLE

Question 9

Type 4 hypersensitivity

Answer 9

cell mediated by T cells

contact dermatitis and organ transplant rejection

Question 10

History

Answer 10

timing after exposure
previous and subsequent exposure
rash, swelling, breathing difficulty, wheeze and cough
FH and personal history - atopy

Question 11

3 main ways to test for allergy

Answer 11

skin prick testing
RAST testing - IgE
food challenge testing

Question 12

What do skin prick testing and RAST testing assess?

Answer 12

sensitisation not allergy

Question 13

Gold standard for diagnosis

Answer 13

food challenge testing

Question 14

How is skin prick testing done?

Answer 14

forearm
drop of allergen eg peanut, house dust mite and pollen
water control and histamine control
15 mins, size of wheals

Question 15

What is patch testing good for?

Answer 15

allergic contact dermatitis

Question 16

RAST testing

Answer 16

total and allergen specific IgE

asthma and eczema

Question 17

Management of allergies

Answer 17

establish allergen and avoid
prophylactic antihistamines
adrenalin auto-injector
immunotherapy

Question 18

Treatment following exposure to allergen

Answer 18

antihistamine eg cetrizine
steroids eg oral prednisolone
im adrenalin

Question 19

What causes anaphylaxis?

Answer 19

severe type 1 hypersensitivity

mast cells rapidly release histamine

Question 20

key feature differentiating anaphylaxis from non-anaphylactic?

Answer 20

compromise of airway, breathing or circulation

Question 21

Presentation of anaphylaxis

Answer 21

urticaria, itching, angioedema
abdominal pain
SOB, wheeze, stridor
tachycardia, collapse

Question 22

ABCDE of anaphylaxis

Answer 22

secure the airway 
oxygen, salbutamol for breathing 
IV bolus of fluids 
lie patient flat to improve cerebral perfusion 
flushing, urticaria and angio-oedema

Question 23

3 medications anaphylaxis

Answer 23

im adrenalin (repeat after 5 mins if required)
antihistamines eg chlorphenamine or cetrizine
steroids - IV hydrocortisone

Question 24

Why should children have a period of assessment after anaphylaxis?

Answer 24

biphasic reactions

Question 25

Confirming anaphylaxis

Answer 25

serum mast cell tryptase within 6 hours of event

Question 26

what is tryptase?

Answer 26

released during mast cell degranulation

Question 27

Time frame to measure mast cell tryptase

Answer 27

within 6 hours

Question 28

Allergy risk factors to give epipen

Answer 28

asthma requiring inhaled steroids 
rural locations 
adolescents 
nut allergies 
co-morbidities

Question 29

using adrenalin auto-injector

Answer 29

remove safety cap
grip device in fist
jab device outer thigh until click 
hold for 3 seconds
remove and massage area 10seconds