Allergy Flashcards
(100 cards)
1
Q
Drugs most likely to be allergic to
A
Penicillin - offer testing so can access antibiotics
Cephalosporins
Anesthetic agents
2
Q
Type 1 hypersensitivity
A
Immediate
Anaphylaxis, allergy
IgE mediated
3
Q
Type II hypersenstivity reaction
A
Cytotoxic T cells
Anitbody and/or complemetn against cell surface
Incl gracves disease and myasthenia gravis
4
Q
Type III HS reaction
A
Immune complex mediated
-> deposition in tissues - inflammation
Rheuamtoid arhtritis, SLE
5
Q
HS reaction/type IV
A
Delayed
T cell mediated
Steven johnson syndrome, chronic transplant rejection, contact deramtitis
6
Q
IgE released by what
A
Mast cells and basophils
Makes them release histamines et
7
Q
Three pahses of anaphylaxis
A
Sesnsitisation
Immediate phase reaction
Late phas reaction 6-12 hours after first symptoms
8
Q
Sensitisation
A
Allergens -> APCs -> MHC II and antigens -> naive T cells + IL-4 -> Th2 cells -> B cell activation -> class switching -> IgE antibody specific to allergen.
Coat surface of mast cells in circulation
9
Q
Immediate phase reaction
A
Allergen encountered - IgE Cross linking on surface of mast cell -> degranulation mast cell -> histamine and triptase release
10
Q
Effect of histamine release
A
Oedema, itching, rash
Bronchoconstriction, mucous secretion, reduced cardiac contractility, increased vascular pereability, vasoconstriction, venodilation - reduce blood to tissues and heart
11
Q
Clinical features of anaphylaxis resp
A
SOB
Tachypnoea
Wheeze or stridor
Chest tightness
Resp arrest
12
Q
CVS symtpoms of anaphylaxis
A
Tachy/brady
Palpitations
Hypotension/collapse
Cardiac arrest
13
Q
GI symtpoms anaphylaxis and skin
A
ABdo pain
N+V, diarrhoea
Hypoglycaemia
Urticaria
Angioedema
14
Q
CNS symtpoms in anaphylaxis
A
Feeling of impending doom
Headache
Altered mental status
Confusion, drowsiness
15
Q
Mild symptoms of anaphylaxis
A
Oral symptoms
Urticaria
Angioedema - incl facial aslong as doesnt compromise airway
16
Q
Modertae allergy symptoms
A
Abdominal pain
N+V, diarrhoea
Mild wheeze
Lum in throat
17
Q
Treatment for mild/mod allergy
A
Mild - oral antihistamines
Mod - oral antihistamines +/- oral steroids + monitoring
18
Q
Severe symtpoms or anaphylaxis
A
Any compromise of AW, breathing or circulation
19
Q
What causes late phas reaction 6-12 hours after initial
A
Eosinophils and basophils - cytokines and leukotriens
20
Q
What can repeat exposure of allergen cause
A
Strucutral damage - allergic rhinitis, allergic asthma
21
Q
What is ahypersensitivity reaction
A
Reaction to normally harmless substance tolerated by others who are not allergic
22
Q
What is delayed systemic allergy
A
Food protein indued enterocolitis - FPIES
23
Q
IgE mediated allergy features
A
Acute onset, immediate
Release of histamine via IgE mechanisms
Urticaria, angioedema
24
Q
Features of non IgE mediated allergy
A
Delayed onset, T cell mediated
Release of histamine via non IgE mechanisms
Dysmotility, eosinophilic oesophagitis, FPIES
25
Types of immune mediated food allergy
Cell mediated
Mixed IgE and nonIgE mediated
Non IgE mediated
IgE mediated
26
Allergic co-morbidities
Atopic dermatitis - eczema
Food allergy
Allergic rhinitis
Atopic asthma
Drug allergy
27
Clues to food allergy
Timing
Nature
Reproducibility
Amount of allergen
Tolerated before or not
28
IgE mediated skin
Pruritis
Eyrthema
Acute urticaria localised or generalised
Acute angioedema - lips, face and around eyes
29
Non IgE mediated skin reaction
Pruritis
Erythema
Atopic suppurative eczema
Refer multi system organ disease
30
What causes atopic dermatitis more high risk for food alelrgy
Genetic predisoposition- filaggrin mutation -> low collagen and elasticity -> sensitisation of all allergens through broken skin barrier -> high risk
31
Eczema linked confitions
Food allergies
Eczema herpeticum
Stpah aureus/strep infection
32
IgE mediated GI symptoms
Angioedema lips, tongue and palate
Oral pruritis
Nausea
Colicky abdo pain
Vomitting, diarrhoea
Faltering growth
33
Non IgE mediated GI symtpomms
Delayed, due to gutwall infalmmation
GORD
loos or frequent stools
Blood +/- mucus in stools
Abdo pain
Infantile colic
Food refusal or aversion
Constipation
Perianal redeness
Pallor and tiredness
Faltering growth
34
Most common food allergies
Cows milk
Eggs
Nits
Fish
Shellfish
Soya
Wheat Kiwi
35
Rescue medication pack for food allergy
ANtihistamine eg cetirazine
If asthma:
Bronchodilator eg salbutamol
Adrenaline auto-injector
36
What risks do not take with food allergy
Abroad
Remote area
Exercising
Dining out
37
Examination for allergy
Growth and physical signs of malnutrition and signs indicating allergy related co-morbidities
38
When consider non IgE mediated food allergy
atopic eczema, GORD, chronic GI symptoms, wheeze dont resolve on treatemnt
Consider dysphagia, water chasing, bolus obstruction in eosinophilic oesophagitis
39
When should food allergy be cnosidered in hildren
Faltering growth
Malnutrition
Pscyhlogu - anxiety, food refusal
40
What is best investigations for IgE mediated allergy suspected
Skin prick testing
Speciic IgE testing
41
What does positive result of skin prick or IgE test mean
Sensitisation - does not mean confirmed allergy, may have asymtomatic sensitisation
42
What use as control in skin prick test
Saline
Some people will react just to pressure if sesntiive skin - dermographism
43
Pros of skin prick testing
Rpaid
Wide range of allergens
Relatively cheap
Good sepcificity and les sprone to fals positives than bloods in atopic individuals
44
Cons of skin prick tsting
Risk of allergy reaction
Difficult if skin pathology
Cant be on antihitamines/antipsychtoics
Labour intesive
45
What is specific IgE testing
Enzyme immunoassay, IgE sitcks, incubates with anti-IgE antibody -> colour chagen
Quantitivae result - <0.35 is negative
46
Pros and cons of specific IgE testign
No risk of reaction as no allergenc exposure
Not affected by drugs
Wide range of allergens
Individual compinenets can test
Cons - False positives esp in atopy (raised total IgE), expensive, some allergens not available, variable sensitivity
47
What is intradermal testing
rug allergy testing - bleb injected into skin Diluted drug
Start w skin prick test then move onto this
Validated for small number of drugs, often antibiotics
48
What is gold test in allergy
Food and drug challenge
49
What is food and drug challenege pors and cons
Observed environemtn
Treatemnt readily available
If tolerated rules out allerfy
Difficutl differentiate non allergy symptoms and allergic symptoms
50
Test for contact dermatitis (IVHS)
Patch testing - 48-72 hrs and see if erythematous reaction
Derm
Not useful in IgE mediated alergy
51
ABCDE signs anaphylaxis
Hoarse voice, stridor
Increase work breathing, wheeze, fatigue, cyanosis, O2<94%
Low BP, shock, confusion, reduced consciousness
Glushed, urticaria, angioedmea
52
Management of anaphylaxis
Remove trigger - stop any infusion
Lie patient falt iwth legs elevated (sat may be easier to breathe)
Pregnant lie on LHS
IM adrenaline 500mg 1:1000
O2 if 94-98%
IV fluid (IO if no route)
Consider bronchodilators eg salbutamol, iatropium neb aswell as further adrenaline first
53
What are not part of emergency treatment for anaphylacis
Steroids - refractory w ashtma/shock
Antihistamines (AVOID chloramphenamine - sedating)
54
What is refractory anaphylaxis
Support needed after 2 doses of adrenaline
ITU
55
Investigations in anaphylaxis
12 lead ECG
CXR
U+Es
ABGs
Mast cell tryptase
56
Mast cell peak
1 hr after sypmtom onset
56
Mast cell triptase when take
Minimum one within 2 hours of anaphylaxis, no later than 4 hours after symptom onset
Ideally 3 times - asap after treatment, 1-2 hrs but not later than 4, at least 24 hours after complete resolution
57
When can you consider fast track discharge after anaphylaxis (2 hrs after resolution)
Good response 5-10 minutes to single dose adrenaline given 30 mins onset
Complete symptom resolution
Unused adrenaline auto-injectors at home and trained
Adequate supervision following discharge
58
When do you keep patient in for minimum 6 hrs observation after resolution
2 doses IM adrenaline needed
Prev biphasic reaction
59
When do you need to monitor a patient for 12 hours after resolution symptoms
Sev reaction requiring >2 doses of adrenaline
Sev asthma or reaction incl sev resp compromise
Possibility of continuing absorption of allergen eg slow release medicines
Late at night presenation - may not respond to deterioration
Areas where access to emergency care is difficuly
60
What give with discharge from anaphylaxis
Consider prescribing adernaline auto-injectors to everyone (except maybe drug, esp if unknown or common allergen)
Specialist refer
Patient education signs and symtpoms
Register anaphylaxis at the anaphylaxis registry
61
Who shld adrenaline autoinjectors have cautino in
Cardiovascular disease esp if on beta blockers
Less effective
Rebound hypertension
62
How many pens do patients need to carry
2
First device may not work or not get full dose
May need a second dose before get to a+e
63
LOOK AT RESUS COUNCIL GUIDELINES
64
What is urticaria and what cuses it
Superficial swelling of skin - epidermis and mucous membranes -> red, raised ithy rash
Can have pale centre
Surrounding ey=rythema - wheels
Histamine causes
65
wHAT IS ANGIOEDMEA and what causes it
Deeper swelling in dermis or SC/submucosal tissues
Can be painfulk
Main mediator = bradykinin
66
Acute vs chronic urticaria and angioedmea
Acute <6 weeks
Chronic >6 weeks, daily
67
Treatment of local reaction to sting etc
Antihistamine eg cetirizine
Prednosolone rescue pack 20mg
Seek medical advise
68
Which resolves faster, urticaria or angioedema
Urticaria - fleeting, returns to normal in 30 mins to 24 hours
Angioedema slower - up to 72 hrs
69
Chronic urticaria features
Females 2:1
Peak 30-40 yrs
More common in atopy
2-3% of pop
70
What is chronic spontaneous urticaria
Spontaneous appearance of wheels/angioedmea for >6 weeks due to unknown causes
71
Types of acute urticaria
Cold
Delayed pressure
Solar
Vibratory
Cholinergic
Contact
Aquagenic
71
Causes of urticaria
Idiopathic
Stress, infection
Meds - NSAIDs, opiates, ACEi (angioedema)
Environemntal - hot, cold, pressure
Minor trauma - dermogrpahism
Exercise
Vibration
Heta
Thyroud dysfunction
Electrolyes - B12, folate, ferriting, vitD
H.pylori infection
Urticarial vasculitis
72
Diagnosis/investigation urticaria bloods
On exam/piture
Bloods - GBC,U+E, LFT,
B12, folate, ferritin, vit D
C4, C1 inhibitor - angioedmea
ANA, TPO/TG antibodies - AI
Provoking tests - cold, heat etc
73
Chronic urticaria prognosis
Often relapsing remitting
Spontaneous resolution 60^ 1 year, 80% 5 years
20% remain symptomatic 10 years
74
Stepwise treatment for urticaria
1 - Standard dose non sdeating H1 antihistamine
2 - Higher dose - 4x recommended dose or add in 2nd antihistamine
3 - Consider a second line agent anti-leukotriene eg montelukast (angioedema - tranexamic acid)
4 - immunomodulant eg omalizumab, cyclosporine, mycophenolate, methotrexate
75
2nd generation antihistamines how use in urticaria
Certizine, loratidine 20mg BD fexofenadine 360mg BD
Daily dose, titrate to higher
76
What can use in severe urticaria
Steroids eg prednisolone for 3-5 dyas
76
When is montelukast esp helpful in urticaria
Conurrent reactivity to aspirin, NSAIDs, AI or pressure urticaria
77
How does cyclosporin treat urticaria
Ibhibits mast cella nd basophil degranulation
78
Side effects of cyclosporin
Headache, nausea tremor, renal impariemtn
79
What need to monitor in cyclosporin
BP, FBC, U+Es, urinalysis
80
What is omalizumab
Monoclonal antibody against IgE
81
What is omaluzimab used in
Treatment of CSU and sev asthma
300mg SC monthly injection
82
When is omaluzimab used in CSU
Severe in adults and children >12 if:
Evidence of disease severity eg UAS7 score >28
Failed maximal medical therapy ie antihistamines + LTRA
83
Side effects of omaluzimab
Injection site reactions
Sinusitis, headache, arthralgia, transient worsening of urticaria
84
How assess urticaria severity
Urticaria actiity score - UAS7
<7 = good control
>28 = severe disease
85
How soon after anaphylaxis can do skin prick test
4-6 weeks
86
Immediate drug reaction features and onset
Urticaria, angioedmea, bronchospasm, N+V abdo pain, anaphylaci
1-6 hrs, typically in 1st
87
Non immediate drug reactions and when
Maculopapular rashes, steven johnson syndrome, toxic epidermal necrolysis, serum sickness, drug fevers, pneumonitis, nephritis
8-12 hrs to days
88
Key areas to consider in relation to drug reactions
Description of reaction
Symptoms sequence and duration
Treatment provided
Outcome
Timing in relation to drug administration
How long had the drug been taken before the onset of the reaction
When was drug stopped ?
What was the effect of stopping the drug
Photograph of reaction illness for which drug was taken (illness may be cause)
Other medications which being taken at the time
Other allergies Other illnesse
89
What is DRESS syndrome
Drug reaction with eosinophilia and systemic symptoms
Begins in 3rd week of being on drug
10% mortality
90
What is allergic rhinpconjucntivitis
Hayfever
91
Signs of vernal conjunctivits
Hard flat topped papillae in cobblestone or pavement stone fashion on conjunctiva
92
Treatment for hayfever
Long act 2nd gen antihistamines eg cetirazine, fexofenadine
Regular nasal steroids
Eye drops - cromoglicate, nedocromil, olopatadine
Start before pollen arrives and maintain throughout season
If poor control oral pred 5-7 dyas
93
What steroid cant use in allet=rgic rhinoconjunctiitis
Kenalog eg triamcinolone
Risk of avascular necorsis of arge joints
94
When is desensitisation therapy indicated in rhinoconjunctivitis
triple therapy, oral steroids required
95
When is desnesitisation helpful and how is it provided
helpful in severe cases and reduces symptoms and need other medication - some may still be required
Requires commitmnet and 3 years of treatment
Continious sublingual therapy or winter courses of 4-6 injections
96
Considering triggers for allergic rhinoconjunctivitis
Infection
Environemntal triggers - smoke, perfume, weather, alcohol, spicy food, stress
Medicines and recreational drugs - ACEis, beta blockers, NSAIds, cocaine
Overuse of nasal congestatnts >5-7 dyas then rebound
Hormone changes- pregnanyc, oubertuy, HRT, OCP
Structural nasal problems - deviated septum, polyps
97
