Medically Fit For Exams
Medically Fit For Exams



  • Chronic immune response
  • Airway obstruction – bronchoconstriction
  • Airway hyperresponsiveness
  • Reversible with β-2 agonists


Risk Factors

  • Other atopic disorders (eczema, allergic rhinitis, atopic dermatitis)
  • Family history
  • Hygiene hypothesis
  • Smoking/parental smoking


Differential diagnoses

  • COPD
  • Bronchitis
  • Bronchiectasis
  • α-1 anti-trypsin deficiency



  • 1/10 children
  • 1/20 adults
  • Hygiene hypothesis – less common if rural, high pathogen exposure, natural birth, fewer antibiotics



  • Genetic
  • Environmental triggers
    • Exercise
    • Emotion
    • Cold air
    • Infection
    • Allergens


Clinical features

  • Dyspnoea
  • Expiratory wheeze
  • Diurnal variation – worse when wake up/wake up with cough
  • Triggered by environmental stimuli
  • Reversible with salbutamol (short-acting beta 2 agonists)
  • Reduced PEV (peak expiratory volume) – peak flow



  • Chronic: increased IgE and CD4 Th2 cells in circulation
  • Allergen/stimulus is presented on antigen-presenting cells
  • Activated CD4 cells and antibodies (IgE) activate mast cells
  • Mast cell degranulation causes release of mediators such as cytokines and histamine that cause eosinophil recruitment and inflammation, and also smooth muscle contraction/bronchoconstriction
  • Chronic inflammation leads to hypertrophy of smooth muscle
  • Fibrosis/remodelling
  • Hyperplasia of goblet cells (secrete mucus)
  • Damaged epithelia (allows future allergens easy access)



  • Peak flow – may appear normal or reduced
  • Peak flow diary - diurnal varation of 20% for >3 days a weeks for 2 weeks
  • Spirometry shows obstructive pattern (FEV1 <80% predicted, FEV1% <70%)
  • Reversibility: 4 puffs (400mg) of salbutamol, wait 15min, FEV should improve by 15% or 400ml. PEFR improves by 20%
  • CXR to rule out other causes



  • Short acting beta-2 agonist (Ventolin/salbutamol) for exacerbations. 1 puff per 30 seconds. If need more than twice a week, is poorly controlled
    • Act on beta-2 receptors, and cause smooth muscle relaxation
    • Inhibit release of mediators from mast cells
  • Long acting beta-2 agonist – salmeterol, taken twice daily as adjunct therapy. Side effects: tremor, tachycardia
  • Theophylline – given if beta agonists don’t work, also cause smooth muscle relaxation
  • Inhaled steroids – Glucocorticoids such as beclomethasone – act as anti-inflammatory drugs, prevent Th2 recruitment of eosinophils and IgE release
  • Oral steroids – prednisolone – not routinely used, but can be if other options don’t work
  • Monoclonal antibodies – anti IgE: omalizumab, in allergic asthma and allergic rhinitis



  • Many asthmatics have poor control, and poor inhaler technique
  • Asthma attack can be fatal
  • Brittle asthma: generally well controlled, but have flare ups and asthma attacks anyway
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