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
signs of asthma
bilateral wheeze on auscaltation
how to classify episodes of asthma
- moderate (PEF 50-75%)
- severe (PEF 33-50%)
- life threatening (PEF <33%)
- fatal
what does microscopy of the mucus in an asthma persons cough show
- Curshmann spirals
- Charcot-Leydig crystals
how to diagnose asthma
PULMONARY FUNCTION TESTS
Pathway:
- do Fraction expired nitrous oxide (feNO) = raised non specific in lung damage
- Then do Spirometry = FEV1:FVC less than 0.7 (obstruction)
- Then do bronchodilator reversibility test = more than 12% increase in FEV1 (REVERSIBLE)
how to treat episodic chronic asthma
- SABA
- ## SABA + ICS
- SABA + ICS + LTRA
- SABA + ICS + LABA +/- LTRA
- Increase ICS dose
before going from 2 to 3 MUST CHECK COMPLIANCE TO MEDICATION AND INHALER TECHNIQUE
how to treat acute asthma (exacerbations)
OSHIT ME
OXYGEN
SABA
HYDROCORTISONE (ICS)
IPRATROPIUM BROMIDE
THEOPHYLLINE
MgSO4 (IV)
Escalate care…
give an example of a SABA
salbutamol
give an example of a LABA
salmoterol
give an example of a SAMA
ipatropium bromide
give an example of a LAMA
triotropium bromide
