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Diagnosing asthma

Diagnosing asthma. History & Physical examination Measurements of lung function Spirometry Peak expiratory flow Measurements of airway hyperresponsiveness Inhaled metacholine /histamine (DIRECT) Inhaled mannitol /exercise challenge (INDIRECT) Measurements of allergic status

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Diagnosing asthma

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  1. Diagnosing asthma • History & Physical examination • Measurements of lung function • Spirometry • Peak expiratory flow • Measurements of airway hyperresponsiveness • Inhaled metacholine/histamine (DIRECT) • Inhaled mannitol/exercise challenge (INDIRECT) • Measurements of allergic status • Skin allergen test & IgE serum

  2. Diagnosing asthma - HISTORY

  3. Diagnosing asthma - HISTORY • Consider asthma if any of the ff. are present: • Frequent episodes of wheezing (>1x/month) • Activity induced cough or wheeze • Cough at night (during period w/o viral infection) • Absence of seasonal variation of wheeze • Symptoms persist after age 3

  4. Diagnosing asthma - HISTORY • Consider asthma if any of the ff. are present: • Symptoms occur or worsen in the presence of: • Animals with fur, aerosol chemicals, changes in temp., domestic dust mites, drugs like aspirin and beta-blockers, exercise, pollen, respiratory viral infections, smoke, strong emotional expression • The childs colds repeatedly “go to the chest” or take more than 10 days to clear up. • Symptoms improve when asthma medication is given

  5. Diagnosing asthma – ROS & PE • Decreased physical activity • General fatigue, inability to sleep • Difficulty keeping up with peers in physical activities • WHEEZING (may be absent if severe) • Breathlessness • Chest tightness • Cough (usually at night or early morning)

  6. Diagnosing asthma – Lung Function Tests 1) Spirometry - preferred method of measuring airflow limitation and its reversibility - Reversibility = increase in FEV1 of >= 12% or 200 mL after administration of bronchodilator

  7. Diagnosing asthma – Lung Function Tests 2) Peak Expiratory Flow (PEF) - PEF measurements are compared to patient’s own best measurements using peak flow meter - Suggests asthma if: • Improvement of 60 L/min or >= 20% of pre-bronchodilator PEF after inhalation of a bronchodilator • Diurnal variation in PEF > 20% (with 2x daily readings more than 10%)

  8. Diagnosing asthma – Measurements of airway hyperresponsiveness • Direct/Indirect airway challenges • Helps in diagnosing asthma in patients with normal lung function but has symptoms consistent with asthma • Reflect sensitivity of airways to factors that can trigger asthma • Expressed as the provocative concentration (or dose) of a given agonist causing a given fall in FEV1 (usually 20%) • Sensitive but not specific

  9. Diagnosing asthma – Measurements of allergic status • Skin test with allergen • Primary diagnostic tool • Simple, rapid to perform, low cost, high senstivity 2) Serum IgE - More expensive

  10. Diagnostic Challenge • Diagnosing asthma in children < 5 years old is largely based on CLINICAL JUDGEMENT, SYMPTOMS, and PHYSICAL FINDINGS • Confirm diagnosis by trial of treatment with bronchodilators & inhaled glucocorticoids • Improves with treatment • Deteriorates when treatment is stopped

  11. Spirometry video

  12. What causes asthma?

  13. Controlling asthma attacks

  14. bronchodilators

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