Asthma

Question 1

Define asthma

Answer 1

Chronic inflammatory airway disease characterised by intermittent reversible airway obstruction, bronchial hyperresponsiveness and inflammation

Question 2

What are the causes/risk factors of asthma?

Answer 2

Acute
• SM contraction -> bronchoconstriction
• Mucus hypersecretion
• Oedema
• Airway obstruction

Chronic
• Proliferation of SM cells and fibroblasts -> airway remodelling
• Family history
• Atopy – eczema, atopic dermatitis, allergic rhinitis

Allergens/precipitants
• House dust mite
• Pollen
• Pets
• Cigarette smoke
• Aspergillus spores
• Drugs e.g. beta-blockers, NSAIDs
• Cold
• Exercise
• Emotion
• Viral respiratory tract infection
• Occupational (isocyanates, epoxy resins)

Question 3

Describe the epidemiology of asthma

Answer 3

Affects 10% of children and 5% of adults

Prevalence is increasing

Question 4

What are the presenting symptoms of asthma?

Answer 4

• Dyspnoea
• Cough
• Wheeze
• Chest tightness
• Nocturnal symptoms
• Worse in the morning

Question 5

What are the signs of asthma?

Answer 5

• Nasal polyps/congestion
• Polyphonic high-pitched expiratory wheeze
• Tachypnoea
• Prolonged expiratory phase
• Hyperinflated chest
• Chest may be silent is severe asthma

Question 6

What are the investigations for asthma?

Answer 6

Acute attack/exacerbation
• Peak flow - mild = >80%; moderate = 60% to 80%; severe = <60%
• Pulse oximetry - mild = >95%; moderate = 91% to 95%; severe = <90%
• Bloods
- FBC - ↑WCC in infective exacerbations
- U&Es
- CRP
• ABG - PaCO2 of <45 mmHg (6.0 kPa) in mild and moderate exacerbations and >45 mmHg in severe exacerbations.
• CXR – may show hyperinflation

Chronic
• Bloods
    - Eosinophilia
    - IgE level
    - Aspergillus antibody titres
• PEFR monitoring – diurnal variation
• Lung function tests – FEV1/FVC ratio <80%, obstructive picture, improvement with beta-2 agonists
• Skin prick test/immunoassay – identify allergens

• diagnosis:
  PEFR varies >20% over 3 days a week over several weeks
  PEFR increases by >20% in response to bronchodilator therapy

Question 7

Describe the management of asthma

Answer 7

Acute attack/exacerbation
• High flow O2 (aim for 94-98% O2 sats)
• Nebulised salbutamol
• 100-200mg hydrocortisone IV -> 40mg oral prednisolone for 5-7 days
- Nebulised ipratropium 0.5mg every 4-6h
- IV magnesium sulphate infusion
- IV aminophylline infusion
- ITU and ventilation
• Monitor O2 saturation, ABG, PEFR, U&Es (↓K)
• Treat the underlying cause! – infection, pneumothorax

*Discharge
• PEFR >75%
• Check inhaler technique
• Stable on discharge meds
• Arrange follow-up

Chronic

1) SABA
2) + ICS
3) + LABA +/- ↑ ICS
4) + ↑↑ ICS or LRA or theophylline
5) + oral steroids

Question 8

What are the complications of asthma?

Answer 8

• Airway remodelling
• Growth retardation
• Chest wall deformity – Harrison’s sulcus
• Acute exacerbations
• Recurrent infections
• Pneumothorax
• Respiratory failure
• Death

Question 9

Describe the prognosis of asthma

Answer 9

Most children improve as they get older

Adult-onset asthma tends to be chronic