allergy r

Question 1

describe the two phases of an allergic reaction

Answer 1

1. mast cell degranulation causing histamine, tryptase and hydrolase release
2. inflammatory mediators like prostaglandins, leukotrines and cytokines are released later

Question 2

effects of histamine

Answer 2

bronchial SM contraction 
vasodilation 
pain
itch 
subcutaneous oedema

Question 3

characteristics of allergy

Answer 3

rapid onset >1hr is unlikely to be allergy
histamine mediated 
urticaria 
erythema 
angioedema 
sweating 
wheeze 
improves with antihistamines

Question 4

features of a mild allergic reaction

Answer 4

urticaria and rash

Question 5

signs of a severe allergic reaction

Answer 5

angioedema or airway - stridor
bronchospasm - wheeze
hypotension - pallor, red blotches, drowsiness

Question 6

what children are at a risk of more severe reactions

Answer 6

children with asthma

Question 7

common triggers of allergic reactions

Answer 7

food 
environmental allergens
drugs 
stings/bites
idiopathic

Question 8

investigations for allergy

Answer 8

skin prick testing
specific IgE blood test
oral food challenge

Question 9

considerations for oral food challenge

Answer 9

this is gold standard
needs to be done in a controlled environment that provides close monitoring
antihistamines and epipens need to be readily accessible

Question 10

management of urticaria and angioedema

Answer 10

avoid triggers
1st line: antihistamines
2nd line: leukotriene antagonist
corticosteroids - short dose

Question 11

when would tranexamic acid be used

Answer 11

in angioedema

not commonly used

Question 12

anti-IgE antibody use in allergy

Answer 12

child must be over 7
6 month course
omalizumab is used

Question 13

presentation of anaphylaxis

Answer 13

laryngeal oedema
hypotension 
bronchospasm 
feeling of impending doom 
rapid onset

Question 14

what is a biphasic reaction

Answer 14

a reaction 1-8hrs after the initial anaphylaxis

give steroids to prevent this and keep patients in hospital overnight

Question 15

risk factors for anaphylaxis

Answer 15

asthma 
stress
exercise 
viral infection 
alcohol

Question 16

doses of adult and child adrenaline auto-injectors (epipens)

Answer 16

adult 0.3mg

junior 0.15mg

Question 17

first line treatment for anaphylaxis

Answer 17

adrenaline auto-injectors

Question 18

actions of adrenaline

Answer 18

reverses peripheral vasodilation 
decreases angioedema
increases peripheral vascular resistance
causes bronchodilation 
decreases release of inflammatory mediators 
improves BP and coronary perfusion

Question 19

when should you prescribe an epipen

Answer 19

if the patient had a systemic reaction
if allergen is hard to avoid 
if they have risk factors like asthma 
if they react to trace amounts 
if they have idiopathic or exercise induced anaphylaxis

Question 20

management of anaphylaxis

Answer 20

ABC
adrenaline
antihistamines
steroids

Question 21

management of allergy

Answer 21

allergen avoidance
antihistamines - use if there is a reaction, not for daily use
adrenaline injectors if indicated
dietary advice - especially in cows milk allergy
optimise asthma control
individualised management plan

Question 22

egg allergy features

Answer 22

common in infants
grow out of it by 5
mild and benign

Question 23

how do you manage egg allergy

Answer 23

initial avoidance but then reintroduce egg using egg ladder

Question 24

features of IgE mediated milk allergy

Answer 24

rapid onset
histamine based
can have vomiting or diarrhoea
identify with skin prick testing or IgE tests

Question 25

features of non-IgE mediated cows milk allergy

Answer 25

more common
not histamine based
varied presentation - diarrhoea, vomiting, irritability, eczema, bloating, PR bleeding
only diagnostic test is dietary exclusion

Question 26

management of cows milk allergy

Answer 26

use an alternative formula
work up milk ladder to reintroduce

AA formulas can be used in infants with severe allergy