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 is the pathophysiology / immune mechanism of
1. sensitisation
2. Allergy
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
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
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
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
How do you manage cows milk protein allergy ?
NOTE- eHF = extensively hydrolysed formula
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?
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
What are some examples of intranasal steroids for allergic rhinitis?
Note: Avamys popular in clinic as ‘ligth’ mist spray
