Allergy Flashcards
Define anaphylaxis
Anaphylaxis is a severe, life-threatening, systemic hypersensitivity reaction.
It is characterised by rapidly developing, life-threatening problems involving the
airway (pharyngeal or laryngeal oedema) and/or breathing (bronchospasm and/or tachypnoea) and/or circulation (hypotension and/or tachycardia).
In mostcases, there are associated skin and mucosal changes.
What is algorithm for anaphylaxis treatment?
NICE - recommend resus council guidelines
For children:
less than 6m = 100micrograms
6m - 6 yrs = 150 micrograms
6years - 12 years = 300 micrograms
12 + = 500 micrograms
Describe what looking for in ABCDE assessment of anaphylaxis?
- Airway: (any swelling, hoarseness, stridor?)
- Breathing (rate ↑, wheeze, fatigue, cyanosis, SPO2
<92%?) - Circulation (pale, clammy, BP↓, faints?
- Disability (confusion, conscious level eg drowsy/coma?)
- Exposure of skin (erythema/urticaria/angio-oedema?).
What are life threatening signs in anaphlyaxis?
A,B,C
What are the doses of IM adrenaline for anaphylaxis treatment?
Age dependant
For an IV / IO fluid challenge for a child suffering anaphylaxis -
1. indications?
2. how many ml should you give ?
- hypotension/ shock/ poor response to initial dose of adrenaline
- crystalloid e.g. hartmann’s / 0.9% saline
* 10ml/kg for children
What other treatments for anaphlyaxis (adrenaline the priority and given some fluids)
- 02 give as soon as available target 94-98%
- Antihistamines (for skin symptoms) e..g non sedating cetirizine (IM/IV) better as chlorphenamine causes sedation
- steroids - consider after resus or ongoing asthma / shock
- bronchodilators e.g. salbutamol / ipratropium (asthma)
- nebulised adrenaline sometimes used as well as IM/IV adrenaline for upper airway obstruction
What are common causes of anaphylaxis in children?
- Food
- Drugs
- Wasp and Bee Venom
- Latex
- Allergen immunotherapy
- Exercise: Food-specific exercise, post-prandial (non-food specific)
- Vaccinations
- Idiopathic
What is biphasic reaction in anaphylaxis?
After complete recovery of anaphylaxis, a recurrence of symptoms can occur within 72 hours with no further exposure to the allergen. It is managed in the same way as anaphylaxis. However, most commonly this occurs within 8-10 hours. (rare)
What should be continuously monitored in a child with anaphylaxis?
- Pulse
- BP
- SP02
- ECG
- cardiac arrest - start CPR
Discharge criteria and discharge checklist for anaphylaxis?
I think vague idea of discharge checklist good for osce etc
Discharge checklst
* contact allergy consultant for management plan
* record allergy on nerve centre/child records/ hospital notes
* oftter patient / parent an adrenaline auto injector for interim before spealist allergy appointment
* written emergency action plan - signs and symptoms etc. and train pt to use autoinjector with dummy adrenaline device
* Prescribe: adrenaline auto injection (specify name of device) and non sedating antihistamine (cetrizine)
* info on biphasic reaction and trigger avoidance
* anaphylaxis info leaflet
Think broadly about a presentation of ‘the allergic child’
give differencials and features of them
Think broadly about what need from:
History
examination
investigations and what looking for
for differneet types of allergy in a child’s presentation
What is acute urticaria ?
how common, pathophysiology, what can it occur with?
- Urticaria (hives) is caused by mast cell degranulation of histamine and vasoactive mediators that cause localized vasodilatation and ↑ capillary permeability. It is characterized by wheal or urticarial plaque.
- Acute urticaria is common, affecting up to 5–15% of children.
- Caused by mast cell histamine release and characterized by itchy wheals.
- It can occur with angio-oedema, which is non-histamine-mediated deep tissue swelling that is NOT itchy.
Causes of acute urticaria?
- Allergic: ingested or injected allergens, e.g. food, drugs.
- Infections: commonly viral infections, EBV, hepatitis B, Lyme disease, cat-scratch disease, parasitic infections.
- Contact urticaria: e.g. from plants or insect bites.
- Physical: sunlight, pressure (dermatographism), aquagenic, heat, cold—familial or acquired (e.g. Mycoplasma).
- Autoimmune and vasculitic conditions: e.g. coeliac disease, HSP.
How to diagnose acute urticaria?
- Detailed history, focusing on triggering events and family history.
- Assess for dermatographism (e.g. gently scratch the volar aspect of the forearm and look for a matching wheal after a few minutes).
- Physical provocation tests can be performed in clinic (e.g. with ice).
Compare and contrast length of duration for acute and chronic urticaria
Acute:
* lasts < 6 weeks
Chronic:
* daily symptoms >3 months
* usually regresses after 2-3 years
- note can get acute intermitting i.e. recurrent episodes lasting < 6 weeks
Causes of chronic urticaria?
- Up to 50% of cases of chronic urticaria are idiopathic.
- Chronic infections, e.g. parasites, Candida.
- Foods.
- Physical urticaria: e.g. dermographism, delayed pressure, cholinergic, cold, etc.
- Autoantibody-stimulating mast cells.
Presentation of chronic urticaria
- Rapidly developing erythematous eruption with central white wheals.
- May have angio-oedema.
- May have annular and arcuate-shaped plaques.
- Any part of the body can be affected and often itchy.
- Lesions last 4–24h and may have associated fever and arthralgia (serum sickness).
Investigations for chronic urticaria?
- Skin prick testing (may not help)
- food and symptoms diary
- stool study ( threadworms, oocytes and parasites)
See image baseline and additional investigations
What medications should you avoid in a child with chronic urticaria?
Avoid medications that cause mast cell degranulation (NSAIDs, codeine/opioids, muscle relaxants, contrast, and some food dyes).
What is treatment for chronic urticaria
With a dermatologist :
- First-line: high-dose antihistamine, e.g. cetirizine up to 40mg/day.
- Leukotriene receptor antagonist as additional therapy
- Severe: add short-course PO prednisolone 0.5mg/kg/day, weaning over 3wk.
- Anti-IgE therapy (omalizumab) is also effective in severe cases.
What is angio-oedema ?
Variant of urticaria with significant swelling of subcutaneous tissues—often involves lips, eyelids, genitalia, tongue, or larynx.
If severe, may cause acute upper or lower respiratory tract obstruction and may be life-threatening.
What is allergy?
Define key words in allergy medicine:
- Allergen
- Sensitivity
- Hypersensitivity
- Sensitisation
- Allergy
- Atopy
- Anaphylaxsis
Tell me about the difference between sensitisation and allergy (think about IgE and clinical symptoms)
Sensitisation - have IgE production but no symptoms suggesting immediate allergy - ‘ silent’ - risk of getting an allergic disease.
Allergy- have current sensitisation which corresponds to specific IgE clinical symptoms- Allergy
What are 8 major allergic diseases? give brief differenciating features for them
When evaluating a child with a suspected FOOD allergy what should you include in the:
- Medical hx
- physical examination
- screening tests
- diagnostic verification
The EATERS history is a way of thinking about the context of a suspected allergic reaction. It includes asking about:
- the exposure
and what other 5 things?
How do IgE mediated and non IgE mediated reactions differ in timings?
IgE reactions - often immediate
Non IgE - (e.g. milk) often delayed
Compare IgE vs Non IgE mediated presenting symptoms
prompts: skin, GI, Resp, CVS
The ‘Food allergy march’ - describes how common food allergies change as a child ages. What are the most common in
- infancy
- early childhood
- adolescence
- infancy
* Milk
* Egg
* peanut - Early childhood
* Soya
* Wheat
* Tree nuts
* Fish, shellfish
* Kiwi
* Sesame - Adolescence
* fresh fruit + vegetables
Heating foods can affect their allegenicity.
- What foods can be tolerated when heated and what does this mean for a child in their everyday life?
- Cows milk - 70% milk allergic can tolerate baked milk in wheat
- Eggs - well cooked a lot less allergenic - 70% can tolerate baked egg in wheat
- peanuts - less allergenic if boiled / fried
- fish - very heat stable but canned tuna and salmon less allergenic
- Apples - when heated / processed - VERY well tolerated
If you are allergic to one food - the allergens can cross react to other similar foods.
If allergic to the below what else might you be at risk of allergy to?
- Cows milk
- Tree nuts
- fish
- shellfish
- Pollen
What type of hypersensitivity reaction is an IgE mediated food allergy?
Type 1 hypersensitivty reaction
What is the pathophysiology / immune mechanism of
1. sensitisation
2. Allergy
What tests / investigations for suspected allergy?
- Skin prick test
- Blood specific IgE- immuunoassay of serum sIgE
- IgE and non-IgE - elimination diet
What do you need to explain when interpreting allergy tests with patients?
Allergy tests detect sensitisation NOT allergy
* need to be interpreted in clinical context
* cannot translate into a CLINICAL ALLERGY
* tests are good at excluding allergy not diagnosing
* can confirm diagnosis of a food allergy if there has been a recent reaction
What is the difference between serum IgE and Skin prick test of IgE?
Skin prick:
* detects IgE bound to skin mast cells
Serum IgE:
* detects circulating IgE in blood
Can skin prick test / serum IgE level tell you how severe the allergy is?
- no
- tells you if there is sensitivity to allergens
- level of serum IgE or size of skin prick result correlates with liklihood of allergy
- does not correlate w/ severity of allergy
What is cow’s milk protein allergy?
Reproducible adverse reaction to one or more milk proteins (casein ± whey) mediated by one or more immune mechanisms (IgE- or non-IgE-mediated).
Pathophysiology of IgE vs non IgE mediated cows milk protein allergy?
IgE-mediated:
A type-I hypersensitivity reaction. CD4+ TH2 cells stimulate B cells to produce IgE antibodies against cow’s milk protein which trigger the release of of histamine and other cytokines from mast cells and basophils.
Non-IgE-mediated:
Involves T cell activation against cow’s milk protein.
At what age does cow’s milk protein allergy present?
does IgE / non-IgE affect presentation?
- all present before 12 months
Yes can be a delay to presentation :
* can be weeks - IgE
* non IgE CMPA - up to 32 weeks
Risk Factors for cow’s milk protein allergy?
Protective factors?
- Personal history of atopy (eg. asthma, eczema, allergic rhinitis, other food allergies)
- Family history of atopy (only allergic predisposition is inherited, not specific allergies)
- Exclusively breastfeeding is possibly a protective factor
How might a child with cow’s milk allergy present? (Dr Luyt)
Wide variation in symptoms - see image
Non-IgE
* rectal bleeding
IgE:
* urticaria to anaphylaxis
Clinical features of cows milk protein allergy in history.
Differenciate between IgE vs non IgE based on:
Speed of onset of symptoms
Teach me Paeds categorise as: speed of onset, skin, GI, respiratory
IgE Mediated:
* Acute and frequently has a rapid onset (up to 2 hours after ingestion)
Non IgE mediated:
* Non-acute and generally delayed (manifest up to 48 hours or even 1 week after ingestion)
Clinical features of cows milk protein allergy in history.
Differenciate between IgE vs non IgE based on:
Skin reactions
IgE mediated
* Pruritis
* Erythema
* acute urticaria - generalised or local
* Acute angio-oedema - lips / face/ eyes
Non-IgE mediated
* Pruritis
* Erythema
* Atopic eczema
Clinical features of cows milk protein allergy in history.
Differenciate between IgE vs non IgE based on:
GI symptoms
IgE mediated:
* Angio-oedema lips tongue, palate
* oral pruritis
* nausea
* colicky abdominal pain
* vomiting
* diarrhoea
Non-IgE mediated:
* GORD
* loose / frequent stools
* blood / mucus in stool
* abdo pain
* infantile colic
* food refusal
* constipation
* perianal redness
* pallor / tiredness
* faltering growth + one or more GI symptoms above (with or without significant atopic eczema)
Clinical features of cows milk protein allergy in history.
Differenciate between IgE vs non IgE based on:
Respiratory symptoms
IgE mediated:
* LRTI symptoms - cough, chest tightness, wheezing, SOB
* URTI - nasal itching, rhinorrhoea, congestion +/- conjunctivitis
Non-IgE
* LRTI (above)
What to include in a focused allergy history?
teach me paeds
- Personal and family history of atopy
- Diet and feeding history of infant
- Mother’s diet if breastfed
- Any previous management used for symptoms
- Which milk/foods
- Age of onset
- Speed of onset following exposure
- Duration
- Severity and frequency of occurrence
- Setting of reaction
- Reproducibility of symptoms
What should you look for in examination of a child with suspected cows milk protein allergy?
General:
* physical examination
* Signs of atopic comorbidities - asthma, eczema, allergic rhinitis.
GI:
* specifically signs of malnutrition.
Review:
* growth charts
What complications and the prognosis of cow’s milk protein allergy ?
commonest cause of food allergy death
Prognosis - Good:
* most tolerate milk by 5
* earlier tolerance to baked milk
* small number remain allergic
Complications:
* malabsorption
* reduced intake - chronic iron-deficiency anameia and faltering growth
* Anaphylaxis - rare
What is the prognosis of cow’s milk protein allergy ?
commonest cause of food allergy death
Good:
* most tolerate milk by 5
* earlier tolerance to baked milk
* small number remain allergic
What are some differencial diagnosis (and their features) for cow’s milk protein allergy?
Teach me Paeds:
* Food intolerance (eg. lactose) - abdominal pain and diarrhoea following exposure to certain foodstuffs
* Allergic reaction to other food or non-food allergens
* Anatomical abnormalities such as Meckel’s diverticulum
* Chronic GI (e.g. gastro-oesophageal reflux disease, coeliac disease, inflammatory bowel disease, constipation, gastroenteritis)
* Pancreatic insufficiency (eg. as a complication of cystic fibrosis)
* UTI
DR LUYT - IMAGE
WHat is FPIES - food protein enterocolitis syndrome?
non-IgE mediated food hypersensitivity
When does FPIES - food protein enterocolitis syndrome present?
Usually presents in infancy
What are the symptoms + signs (and timing of) of FPIES - food protein enterocolitis syndrome?
- Symptoms delayed 1-3 hours after contact
- Profuse repetitive vomiting leading to shock.
- Occasional watery diarrhoea (affecting 25%).
- Pallor and shock.
Why is diagnosis of FPIES - food protein enterocolitis syndrome often missed?
- Symptoms delayed 1-3 hours after ingestion.
- Symptoms atypical of food allergy.
- Appears like acute onset sepsis.
- WCC can be elevated; CRP normal.
What are triggering foods for FPIES - food protein enterocolitis syndrome?
- Milk, soya, eggs, rice (commonest in infants)
- Meat, poultry, seafood, vegetables.
How do you manage cows milk protein allergy ?
NOTE- eHF = extensively hydrolysed formula
What are milk substitutes for formula fed infants who have cows milk protein allery?
1st line: Extensively hydrolysed formula:
* cheaper, made from cow’s milk but the casein and whey are broken down into smaller peptides which are less immunogenic.
* 90% of children with CMPA will respond to this.
2nd line: Amino acid formula:
* more expensive, second-line formula for the 10% children who continue to have symptoms despite using hydrolysed formula or who have very severe symptoms.
Soya-based formulas are NOT recommended in infants <6 months :
* weak oestrogenic effect of isoflavones
* absorption of minerals and trace elements may be inhibited by phytate found in this milk.
What is the difference between Lactose intolerance and milk allergy?
Lactose deficiency - cabohydrate
milk allergy - protein
What is lactose deficiency?
- clinical syndrome in which lactose or lactose-containing foods causes symptoms (abdominal pain, bloating, flatulence, nausea, diarrhoea).
- Asian/African children have low lactase by school age.
- Caucasian have persistent lactase to adulthoo
What is:
1. Lactase deficiency
2. Lactose malabsorption
- Lactase deficiency: intestinal brush border lactase enzyme activity lower than normal.
- Lactose malabsorption: small bowel fails to absorb lactose because of lactase deficiency.
5-year-old male is referred by his GP. He was at a friend’s party where there were sweets and snacks to eat. He developed acute symptoms of agitation, erythema of his face and then vomited profusely.
Tell me how you would assess?
History:
* Exposure: What has he eaten?
* Allergen: Consider common allergens.
* Timing: Immediate symptoms.
* Environs: Most reactions on first contact. Reproducibility: First reaction.
* Symptoms e.g.:
1. Skin – erythema?
2. Respiratory – ?
3. GIT – vomiting?
4. CVS – ?
Past medical history
* Any atopic background e.g., eczema. Any previous allergic reactions?
Examination:
* Eczema, rhinitis?
Dietary history:
* What do the like / not like
* what have they not tried yet ?
* nuts? if no, why?
How to manage food allergy and anaphlyaxis
Dietary advice
* Exclusions: accurately identify offending allergens.
* Inclusions: assess for potentially cross-reacting allergens and avoid exclusion of allergens able to tolerate
Reading labels in packaged foodstuffs
* 4 ‘major’ allergens labelled in bold.
* Contaminants are Patient advisory labels. i.e.,’ may contain”
Risk advice
* Eating ‘un-packaged food’ (no need for labelling). Eating in restaurants; light meals (at mall, airport).
* Travel advice i.e., eating on plane, in foreign countries.
**Medical advice **
Does the child need an EPI PEN? When to use and how to use?
Can food exclusion make eczema better?
NO!
Dr Luyt: food allergy does not cause eczema. liklihood of diet imporving milk eczema is 0.
Dont do lots of testing wihtout an allergy focused history or get lots of false positives
What is rhinitis?
Inflammatory disorder of the nasal mucosa initiated by an allergic immune response to inhaled allergens in sensitised individuals (often non-allergic in younger children).
What is rhinitis charachterised by?
Characterised by one or more of:
- nasal congestion
- rhinorrhoea
- sneezing and itching.
6-year-old male is referred by his GP. He has a persistently blocked and runny nose and frequently gets URTIs. He also coughs at night, snores and
has disturbed sleep. He has been given Piriton which helps a little but does not take the symptoms away. Symptoms year round.
What more do you want to know?
Age of onset?
Anything worsen it?
Atypical/other symptoms of congestion?:
* Earache; recurrent ear infections.
* Problem with speech or hearing.
* Headaches.
Atypical/other symptoms of rhinorrhoea?:
* Cough at night/with activity.
* Sore throat; bad breath.
* Stomach aches; poor appetite.
Sleep problems ?
6-year-old male is referred by his GP. He has a persistently blocked and runny nose and frequently gets URTIs. He also coughs at night, snores and
has disturbed sleep. He has been given Piriton which helps a little but does not take the symptoms away. Symptoms year round.
What would you expect on examination?
Allergic facies:
* allergic shiners.
* Swollen mid-face.
* Mouth breather.
* Allergic crease.
Bad breath/halitosis.
Speech – loses high-pitched sounds.
ENT:
* Swollen nasal turbinates.
* Nasal mucus – clear in rhinitis.
* Ears: dull retracted ear drums.
Chest:
* evidence of concomitant asthma.
What is this?
Clinical presentation of allergic facies in allergic rhinitis
what is this?
Allergic ‘shiners’
what is this?
swollen nasal turbinates in allergic rhinitis
What antihistamines available for allergic rhinitis?
Fexofenadine = gold standard
Cetirizine = also used in clinic
Why is fexofenadine not sedating?
Does not cross the BBB - no sedating effects
Why is fexofenadine not sedating?
Does not cross the BBB - no sedating effects
What are some examples of intranasal steroids for allergic rhinitis?
Note: Avamys popular in clinic as ‘ligth’ mist spray
What is immunotherapy in context of allergies?
Involves administering the allergen to which the patient is sensitised.
Only disease-modifying treatment available for several allergic diseases.
Commercially available in sublingual (grass, HDM) and subcutaneous (bee, wasp) forms.
