Transcript File

Allergy in General
practice
Naomi Oliver
Why?
• Common presentation in general practice
• Hopefully not covered recently during a VTS session
• Recently had an FGM presentation
Learning objectives
• To be aware of the indications for testing for food allergies
• To become familiar with allergy tests
• To have a better understanding of the Management of allergic
and contact Dermatitis
• To have a better understanding of the Management of Allergic
Rhinitis
• To have a better understanding of the Management of
Urticaraia
• To have a better understanding of the Management of
Anaphylaxis in primary care
• Referral guidelines to secondary care for allergic conditions
Curriculum mapping:
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3.03 Care of Acutely Ill People (Anaphylaxis)
3.15 Care of People with ENT, Oral and Facial Problems
3.19 Respiratory Health
3.21 Care of People with Skin Problems
An interesting case for
discussion
• 29 year old female
• Haematology ward, being treated for an unknown
haematological malignancy
• PMH: Nil, allergies: Anaphylaxis to nuts
• Bleeped at 5.30pm to re-site cannula for 2nd unit of blood to
be given
• 6pm (ish) fast bleeped to ward, anaphylactic reaction
• Why did this occur?
Allergic transfusion reaction
• Caused by the passive transfer of peanut antigens in the blood
products
• The major peanut antigen Ara H2 is resistant to digestion
• Well documented cases in literature of patients with known
anaphylactic reactions particularly to peanuts reacting after
receiving blood products after recent digestion of peanuts
from donor.
• Considerations for future donors? Screening questionnaires of
food recently eaten? Period of refraining from eating nuts
before donating blood?
What is an ‘allergy’?
“ Hypersensitivity caused by exposure to a particular antigen
(allergen) resulting in a marked increase in reactivity to that
antigen on subsequent exposure. Sometimes this may result in
harmful consequences” 1
Types of allergic reaction2:
Food allergies:
• Very common, studies suggest levels of food allergies appear
to be increasing.
• NICE guidelines 2011. Differentiate between IgE mediated and
non IgE mediated.
IgE mediated
Non IgE mediated
Pruritis, erythema, diarrhoea and abdominal
pain are common to both types.
Pruritis, erythema, diarrhoea and abdominal
pain are common to both types.
Acute urticaria - localised or generalised.
Acute angio-oedema
Oral itching, nausea, vomiting.
Colicky abdominal pain.
Nasal itching, sneezing, rhinorrhoea, allergic
conjunctivitis.
Cough, shortness of breath, wheezing and
bronchospasm (or history of asthma).
Atopic eczema.
Gastro-oesophageal reflux.
Infantile colic.
Stools: loose and/or frequent, blood and/or
mucus.
Constipation.
Perianal redness.
Pallor and tiredness.
Faltering growth.
Food aversion or avoidance
Food allergies continued
• If you suspect that the allergy is IgE-mediated offer a skin
prick test or blood tests for specific IgE antibodies to the
suspected foods.
• If you suspect that the allergy is non-IgE-mediated allergy
eliminate the suspected allergen for 2-6 weeks, then
reintroduce.
Allergy tests:
Skin Prick testing
Radioallergosorbent test Skin patch testing
(RAST)
Most commonly used
test. Quick and easy.
Drops of diluted antigen
placed on the skin which
is then pierced using a
sterile needle. Can be
interpreted after 1530mins.
Determines the amount
of IgE that reacts with a
suspected allergen.
Results are given in
grades 0 negative to 6
strongly positive.
Up to 40 potential
allergens are placed on
the back. Patches
removed 48 hours and
results interpreted.
Useful for testing food
allergies and pollen.
Theoretical risk of
anaphylaxis.
Need to refrain from
using antihistamines for
at least 5 days.
Useful for food allergies,
pollen and venoms.
Good to use in patients
who are currently taking
antihistamines or have
skin conditions such as
eczema
Useful for contact
dermatitis.
Allergy tests continued:
Allergic contact dermatitis
• Most commonly caused by contact with substances such as
Nickel, cosmetics, rubber chemicals and dyes
• Clinical features: Develops after 1-2 days after exposure
• Skin inflammation, weeping, vesiculation. In chronic stages
can cause dryness, scaling and fissuring. Most common sites
affected ear lobes, nape of neck and wrist.
• Clinical diagnosis but can use patch testing.
• Management: Avoidance, topical corticosteroids, ointments
+/- oral antihistamines
Allergic contact dermatitis
versus irritant dermatitis?
Primary irritant:
• No previous exposure required
• Everyone susceptible to irritant dermatitis.
• Non allergic reaction, due to contact with skin irritants like
acids and alkalis
• Most typically seen after using a hair dye which causes a
weeping eczema.
• Management: Avoidance of trigger and topical steroids
Contact dermatitis:
Allergic rhinitis
• Seasonal: caused by grass and or tree pollen. Symptoms occur
at the same time every year.
• Perennial: caused by house dust mites. Symptoms occur
throughout the year
• Occupational: caused by allergens at work. Symptoms often
improve at weekends and during leave.
• Clinical features: rhinorrhoea, nasal blockage, sneezing, itching
eyes, nose and ears, wheeze, fatigue, malaise
• Clinical diagnosis based on history. However RAST/skin prick
testing can be used for specific allergens like dust mites and
grass/tree pollens.
Allergic rhinitis management:
Medication
Examples:
Antihistamines: oral antihistamines are effective
first-line drugs which relieve ocular symptoms,
nasal irritation, rhinorrhoea and sneezing but has
limited effect on nasal congestion
Cetirizine
Loratidine
Fexofenadine
Corticosteroids: in severe cases systemic steroids,
in the form of a course of low dose oral steroid,
may be used e.g. prednisolone up to 20 mg daily
for up to 5 days.
Prednisolone
nasal corticosteroids - used as first line therapy in
moderate to severe allergic rhinitis.
Fluticasone
Betamethasone
Leukotriene receptor antagonists: used in addition
to antihistamines and nasal corticosteroids.
Monteleukast
Anticholinergic agents: intranasal ipratropium used in watery rhinorrhoea Intranasal
decongestants (short term)
ipatropium
Referral criteria for Rhinitis and
immunotherapy:
• Persistent symptoms despite maximal oral and topical therapy.
Symptoms still persistent for more than 6 weeks with using
intranasal steroids- REFER
• Immunotherapy (increasing amounts of allergens are
administered subcutaneously to an allergic person to minimize
the allergic reaction following exposure to that particular
allergen)
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with persistent moderate to severe symptoms in spite of treatment
who needs systemic corticosteroids
with coexisting diseases like sinusitis, asthma
poor response to nasal corticosteroids
in 1-3% of patients, moderately severe systemic reactions can be
seen
Urticaria
AKA Hives, nettle rash or wheals.
• Acute: < 6 weeks of continuous activity
• Chronic: > 6 weeks of continuous activity.
• Can be categorised by cause: physical (mechanical, thermal), contact
(allergens or chemicals),urticarial vascultitis, and angio oedema
without wheals
• Common causes: Food, drugs (Aspirin, NSAIDs, opiates), infection,
emotional stress
• Urticaria may be associated with: SLE, viral hepatitis, leukaemia and
lymphoma, infections and hereditary angioedema
• Careful history to elicit cause. Ix may be required (FBC, ESR, TFTs,
Autoantibody screens
Urticarial management:
• General principles: Avoidance of triggers e.g.. Stress, alcohol
and medication
• Cooling anti-pruritic treatments (calamine lotion, aqueous
cream)
• Medication: First line: cetirizine, loratidine and fexofenadine.
Can use a sedating anti-histamine if sleep is also an issue.
• Leukotriene receptor antagonists can be used in addition to
antihistamines
• Oral steroids not routinely recommended however can be
used in the short term where patients are not responsive to
antihistamines
• Immunomodulating therapy: Ciclosporin, and tacrolimus for
severe urticaria refractory to treatment
Referral to secondary care:
A patient should be considered for referral to secondary care
(immunologist or dermatologist) , where:
• Uritcaria with angioedema not involving the airway
• Food or latex allergy causing severe acute urticaria
• Chronic persistent urticaria refractory to treatment and
symptoms which are persistent despite avoidance of known
triggers
• Vasculitic uriticaria
Urticaria
Anaphylaxis
Life threatening type 1 hypersensitivity reaction.
Most common precipitants include food (peanuts, almonds, fish,
milk), medications( antibiotics, heparins, contrast media) and
venoms.
Clinical presentation: sudden onset rapidly progressive
symptoms, life threatning airway, breathing or circulatory
symptoms and skin or mucosal symptoms.
(Hypotension, stridor, wheeze, urticaria, abdominal pain, nausea,
pruritius)
However in children presentation may be rather vague to include
pallor, limpness and apnoea.
Management in primary
care:
• Removal of allergen if possible
• ABCDE
• Administer adrenaline! 1in 1000 IM injection (dose can be
repeated every 5 mins if no improvement)
• call ambulance
Children (0 to
6 years)
Children (6-12 Adults (12
years)
years +)
0.15mls/150
micrograms
0.3mls/300
micrograms
0.5mls /500
micrograms
Confirmation of anaphylaxis
• Diagnosed clinically however can be confirmed by measuring
mast cell tryptase. Levels peak immediately during reaction
and up to 4 hours, 2nd level to be taken at 1-2 hours.
• ALL patients should go to hospital. Why? Delayed second
reaction.
• After emergency treatment for suspected anaphylaxis, offer
patients a referral to a specialist allergy service and an IM
adrenaline pen as an interim measure before their
appointment
Summary:
• Common presentation in primary care
• Management should incorporate both prevention and
treatment of active symptoms
• Consider referral to secondary care for symptoms refractory to
treatment
• Steroids are not the mainstay of treatment and should only be
used in certain circumstances
• All patients following anaphylactic treatment should go to
hospital. Be aware of delayed secondary reactions!
Questions
References:
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1.http://medical-dictionary.thefreedictionary.com/allergy
2http://philschatz.com/anatomy-book/contents/m46566.html
GP notebook: Allergic rhinitis, contact dermatitis, Anaphylaxis
Emergency treatment of anaphylactic reactions. Guidelines for
healthcare providers. Working Group of the Resuscitation
Council (UK).2008
• NICE (December 2011). Anaphylaxis: assessment to confirm an
anaphylactic episode and the decision to refer after
emergency treatment for a suspected anaphylactic episode.
• https://www.nice.org.uk/guidance/CG116/chapter/1Guidance