Asthma Flashcards
What is asthma?
A chronic, inflammatory airway disease that is characterised by reversible airway obstruction.
What is meant by atopy?
Tendency of Th2 cells to increase IgE production, on exposure to allergens
What are the 3 characteristic factors of asthma?
- Bronchial SM contraction
- Bronchial inflammation
- Increased mucus production
What is meant by early phase asthma?
Up to 1h
- cross-linking of IgE antibodies on mast cells surface
- release of histamine, leukotrienes, PGD2, TNFa
- causes SM contraction, inflammation + oedema, mucus production leading to OBSTRUCTION
What is meant by late phase asthma?
6-12h
- INFLAMMATION caused by recruitment of eosinophils, basophils, neutrophils and TH2 cells
- AIRWAY REMODELLING - structural cells release cytokines and growth factors, causing proliferation of SM cells and fibroblasts
How would you investigate acute asthma?
- peak expiratory flow meter
- ABG - should have low CO2 due to hyperventilation
- pulse oximetry - ? hypoxia
- CXR - exclude infection/pneumothorax
- FBC, CRP, U&E, sputum
How would you monitor chronic asthma?
- PEFR monitoring - diurnal variation
- PFT - obstructive
- Bloods - eosinophilia, basophilia, IgE
Important parts of a history in an asthmatic person
Episodic wheeze, dyspnoea, cough – diurnal variation common, worse at morning and night
Ask about precipitating factors e.g. cold, dust, cigarette smoke, drugs – NSAIDs, BBs
—PASTO – Pets, Allergies, Smoking, Travel, Occupation
Ask about days off school/work per week to gauge severity.
What signs might you find on examination of an asthmatic?
- Tachypnoea
- Polyphonic wheeze
- Prolonged expiratory phase
- Hyperinflated chest
How might a severe asthma attack present?
- PEFR <50% predicted
- HR >110
- RR >25
- Unable to finish sentences
How might a life-threatening asthma attack present?
- PEFR <33% predicted
- Bradycardia
- Cyanosis
- Hypotension
- Chest silent
How would you manage chronic asthma, according to BTS guidelines?
- SABA – salbutamol
- Inhaled steroid – beclometasone
- LABA – salmeterol ± aminophylline ± Montelukast
- Increase steroid and add B2 agonist tablet/montelukast ?? – check MedEd
- Oral steroids – prednisolone
How would you manage acute asthma?
- Resus + monitor O2, ABG, PEFR if possible
- Salbutamol nebuliser 5mg
- IV hydrocortisone ± PO prednisolone for 5-7 days
- O2 if SaO2 <92% – aim for 94-98%
- If not improving – give IV MgSO4 + aminophylline
How do B2 agonists help in asthma?
bronchial SM relaxation
How do steroids help in asthma?
Reduce bronchial mucosal inflammation - act over days
