Allergy Flashcards
(28 cards)
What is allergy
Type 1 hypersensitive disorder
Exaggerated or inappropriate immune reaction to harmless allergen and causes damage to the host
What can symptoms be
Localised - Rhinitis (upper) - Asthma (lower) Systemic - Anaphylaxis
What are the RF
Hereditary Race Age Environmental exposure Occupational
What happens in sensitisation
Plasma cells produce IgE which binds to mast cells
What happens on re-exposure
Mast cells degranulate
Release of histamine, leukotrienes, prostaglandins and chemotactic factors
What does degranulation cause
Vasodilation Vascular permeability Smooth muscle contraction Nerve stimulation Leucocyte infiltration esp eosinophils
What happens in acute response
Exposure to allergen
Degranulation
Causes sneezing, cough, wheeze, runny nose, weepy eyes and itch
What happens in late response
2-4 hours
Mainly due to cellular immunity
Due to migration of other leucocytes such as neutrophils, lymphocytes, eosinophils and MO
What is allergic rhinitis and what triggers
Allergic inflammation of the nasal airways - type 1 IgE mediated
Occurs when allergen inhaled by individual sensitized
Pollen, dust, pets
Seasonal / intermittent
Perennial - persistent
Occupation
What is associated
Asthma - basically asthma of the nose
Atopic dermatitis
Eczema
Nasal polyps
What are the symptoms
Rhinorrhoea - nasal cavity filled with mucous Clear nasal discharge - bilateral Post nasal drip Watery red itchy eyes - bilateral Sneezing Nasal itch Nasal blockage Hyposmia as olfactory nerves at top Inflammed nasla turbinates
What do late symptoms causes
Vasodilation
Further oedema and blockage
What may occur
Chronic obstruction
What are RF
Atophy FH Exposure to infectious disease Environmental pollution Diet change Allergene exposure
What is intermittent symptoms
<4 days per week or <4 consecutive week
What is persistent
> 4 days and >4 weeks
What suggests mild rhinitis
Normal sleep
No impairment of activities
No impairment work / school
Symptoms present but not trouble system
What is mod-severe
\+1 of Sleep disturbance Impairment of activities Impairment of school or work Troublesome symptoms
What do you do for mild symptoms
Allergen avoidance Nasal irrigation Barrier creams H1 blocking anti-histamine - oral or nasal Topical nasal decongestant LTRA can be useful if also have asthma Topical > systemic
What do you do for persistent symptoms
Review
Step up or continue if worked
What do you do for mod-severe
Intra-nasal corticosteroid + anti-histamine
- Beconase (risk of nose bleed if chronic use)
Occasionally oral steroid during severe symptoms
If failure
Nasal spray technique - if left nostril hold in R hand
Review Dx / compliance
Query infection
Increase intranasal ICS
Add ipatropium if rhinorrhoea
Specialist referral for possible immunotherapy / anti-IgE = very expensive
What tests can be done
Clinical Dx with Hx and exam = sufficient
Skin / patch test - can be done in clinic
- Risk of anaphylaxis
RAST - more expensive
Other
Total serum IgE
Nasal allergen challenge
Nasal cytology
What is RAST
Shows presence and levels of allergen specific IgE
