Allergies Flashcards
What is atopy
Personal or familial tendency to become sensitised and produce IgE antibodies to low doses of allergens and as a consequence develop sx of an allergic disease, eg asthma, rhinitis, hay fever, eczema, food allergens etc
Approach to allergies
Description of symptoms: itchiness, redness, swelling, sneezing, coughing, wheezing
Site of manifestations
Hx of presenting sx
Age of onset , severity, duration,timing, pattern, triggers, ass/sx, response to tx
Management of allergies (4 Pillars of allergy management)
Education
Trigger avoidance
Pharmacotherapy
Allergy immunotherapy
How do we make the dx of allergic rhinitis
2 or more sx for more than an hour per day for more than 2 weeks
Sx: runny nose, itchiness and sneezing
Clinical fx of allergic rhinitis
Dennie-Morgan lines (wrinkles under eyes)
Allergic shiner (darkness under eye)
Transverse nasal crease
Dental malocclusion
Mouth breathing
Pale, swollen, with lots of thin watery mucous Turbinate (nasal canal)
Tx of allergic rhinitis
- Primary anti-inflammatory
Intranasal corticosteroids
Leukotriene receptor amtagonists
Sodium cromoglygate - Block release modulators
Antihistamines
Anticholinergics - Work on physical basis
Decongestants
Which immunotherapy agents would you give to a child with allergic rhinitis
Sublingual immunotherapy
Subcutaneous immunotherapy
What are the 3 patterns of anaphylaxis
Uniphasic: short lived episode, resolves completely within 2hours
Biphasic (20%): first episode which may seem resolves, 8-24 hours later another episode or wave of symptoms more severe than first episode
Protracted (rare): personal remains symptomatic for hours to days
What is Alpha gal syndrome
People with alpha gal syndrome react after eating red meat.
Due to the galactose alpha 1,3 galactose.
Onset is delayed by 2-5 hours after eating red meat because antigen is absorbed via lymphatics, on,y enteric enteric circulation after some time
Alpha gal is highly concentrated in meat like liver, heart and kidney.
Tick bites can also cause cross sensitisation, new onset allergy in adults may be due to this.
How is Radiocontrast media anaphylaxis mediated
Acute onset is caused by mast cell activation via IgE
Delayed, 3hrs to 5days is due to Tcell mediated hypersensitivity reaction
Can prophylactic medications be used to prevent anaphylaxis
e.g antihistamine and corticosteroids
No, worsens attack or prognosis
Which cells must be activated to mediate anaphylaxis
Mast cells and basophils
What sensitivity components directly activate mast cells rather than IgE for anaphylaxis (What are the non immunological causes of anaphylaxis)
RadioContrast media
Exercise induced anaphylaxis
Alcohol
Temperature eg cold exposure or heat
NSAIDs
What investigations can you do to dx anaphylaxis
It is a clinical dx, no special investigations required
however ,
1. IgE sensitisation can be seen in skin or blood test
2. Serial monitoring of tryptase levels, taken at onset of sx, 1 or 2hours later and at resolution of sx. A change from baseline of >2 ng/g has 90% Sensitivity for detecting anaphylaxis
How is the dx of asthma made
- Detailed hx (patterns of sx, exacerbations, exposures, development and tx of disease and if reversed sx immediately with bronchodilator)
- Thorough exam (hyperinflation, barrel chest, prolonged expiration and hoovers sign, wheezing, incr work of breathing)
- Demonstrating lower airway reversibility (1. Peak flow expiratory flow rate- PEFR, from 5y/o, 15% or more improvement after bronchodilator indicates positive response. 2. Spirometry, which is a lung fx test to assess lung volume air flow on insp and exp, FVC, FEV, FEF)
-To make dx of asthma, flow volume loops must show reduced FEV1, normal FVC and reduced FEV1 to FVC ratio.
