asthma Flashcards
define asthma
chronic reversible airway disease characterised by reversible airway obstruction, inflamed bronchioles, airway hypersensitivity and mucus hypersecretion
what are the 2 types of asthma
allergic and non allergic
which type of asthma is more common
allergic - 70%
non allergic is only 30%
describe allergic asthma
- IgE mediated
- extrinsic
- T1 hypersensitivity
- raised eisinophils
what causes allergic asthma
occurs due to an environmental trigger eg:
- pollen
- smoke
- dust
- mould
- antigens
genetics and hygiene hypothesis also impact it
when does allergic asthma usually present
early - affects children
what is the hygiene hypothesis
growing up in a very very hygenic environment increases susceptibility to asthma infection
describe non allergic asthma
- non IgE mediated
- intrinsic
- harder to treat
- associated with smoking
when does non allergic asthma present
may present later than allergic
general triggers for asthma
- infections
- allergens
- cold
- dust
- damp
- exercise
- drugs (Beta blockers, aspirin)
what is the atopic triad
- allergic rhinitis
- atopic eczema
- asthma
some people have all 3 disease together - known as atopy
what is samters triad
- bronchial asthma
- nasal polyps
- aspirin intolerance
pathophysiology of asthma
- overexpressed TH2 cells in airway exposed to trigger
- this stimulates:
- IgE production (mast cell degranulation) → T1 hypersensitivity
- Eosinophilia → release of toxic proteins e.g. MBP
- leading to bronchial constriction and mucus hypersecretion
- over time you get chronic remodelling and bronchial scarring
what do mast cells release when they degranulate
- histamine
- leukotriene
- tryptase
symptoms of asthma
- Wheeze
- dyspnoea
- cough with DIURNAL VARIATION (worse at night) and worse during EPISODES (i.e. not constant)
- chest tightness
- SOB
