Chronic asthma Flashcards
definition of chronic asthma
Episodic, reversible airway obstruction due to bronchial hyper-reactivity to a variety of stimuli.
epidemiology of chronic asthma
- Incidence 5-8% (↑ in children vs. adults)
- Peaks at 5yrs, most outgrow by adolescence
pathophysiology of acute asthma
- Mast cell-Ag interaction → histamine release
- Bronchoconstriction, mucus plugs, mucosal swelling
pathophysiology of chronic asthma
- TH2 cells release IL-3,4,5 → mast cell, eosinophil and B cell recruitment
- Airway remodelling
general causes of asthma
- atopy
- stress
- toxins
atopy causes of asthma
- T1 hypersensitivity to variety of antigens
- Dust mites, pollen, food, animals, fungus
stress causes of asthma
- Cold air
- Viral URTI
- Exercise
- Emotion
toxin causes of asthma
- Smoking, pollution, factory
- Drugs: NSAIDS, β-Blockers
symptoms of chronic asthma
- Cough ± sputum (often at night)
- Wheeze
- Dyspnoea
- Diurnal variation with morning dipping
things to consider when taking an asthma history
- Precipitants
- Diurnal variation
- Exercise tolerance
- Life effects: sleep, work
- Other atopy: hay fever, eczema
- Home and job environment
signs of asthma
- Tachypnoea, tachycardia
- Widespread polyphonic wheeze
- Hyperinflated chest
- ↓ air entry
- Signs of steroid use
diseases associated with asthma
- GORD
- Churg-Strauss
- Allergic Bronchopulmonary Aspergillosis (ABPA)
differential diagnosis of asthma
- pulmonary oedema (cardiac asthma)
- COPD
investigations for asthma
- Bloods
- FBC (eosinophila)
- ↑IgE
- Aspergillus serology - CXR: hyperinflation
- Spirometry
- Obstructive pattern c¯ FEV1:FVC < 0.75
- ≥15% improvement in FEV1 c¯ β-agonist - PEFR monitoring / diary
- Diurnal variation >20%
- Morning dipping - Atopy: skin-prick, radioallergosorbent test (RAST)
general management of asthma
TAME - Technique for inhaler use - Avoidance: allergens, smoke (ing), dust - Monitor: Peak flow diary (2-4x/d) - Educate > Liaise c¯ specialist nurse > Need for Rx compliance > Emergency action plan
drug ladder for chronic asthma (British Thoracic Society Guidelines)
- Short-acting β agonist PRN + low-dose inhaled steroid (beclomethasone 100-400ug bd)
- Long-acting β agonist (salmeterol 50ug bd)
- ↑ inhaled steroid to up to 1000ug bd
- Leukotriene receptor antagonist + Theophylline + Modified-release β agonist PO
- oral steroids (e.g. prednisolone 5-10mg OD)
guidance on use of Long-acting β agonists
- Good response: continue
- Benefit but control still poor: ↑ steroid to 400ug bd
- No benefit: discontinue + ↑ steroid to 400ug bd
If control is still poor consider trial of:
- Leukotriene receptor antagonist (e.g. monetelukast)
> Esp. if exercise- / NSAID-induced asthma
- Sustained-release Theophylline
guidance on use of oral steroids
- Use lowest dose necessary for symptom control
- Maintain high-dose inhaled steroid
- Refer to asthma clinic
