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asthma

asthma

diagnosis in adults

  • Spirometry is the preferred initial test to assess the presence and severity of airflow obstruction
  • PEFR testing: PEF should be recorded as the best of three forced expiratory blows from total lung capacity with a maximum pause of two seconds before blowing. The patient can be standing or sitting. Further blows should be done if the largest two PEF are not within 40 l/min.

suggestive features

  • More than one of the following symptoms: wheeze, breathlessness, chest tightness and cough, particularly if:
    • symptoms worse at night and in the early morning
    • symptoms in response to exercise, allergen exposure and cold air
    • symptoms after taking aspirin or beta blockers
  • History of atopic disorder
  • Family history of asthma and/or atopic disorder
  • Widespread wheeze heard on auscultation of the chest
  • Otherwise unexplained low FEV1 or PEF (historical or serial readings)
  • Otherwise unexplained peripheral blood eosinophilia

features that lower the probability of asthma

  • Prominent dizziness, light-headedness, peripheral tingling
  • Chronic productive cough in the absence of wheeze or breathlessness
  • Repeatedly normal physical examination of chest when symptomatic
  • Voice disturbance
  • Symptoms with colds only
  • Significant smoking history (ie >20 pack-years)
  • Cardiac disease
  • Normal PEF or spirometry when symptomatic
    • NB. a normal spirogram/spirometry when not symptomatic does not exclude the diagnosis of asthma. Repeated measurements of lung function are often more informative than a single assessment.

further Ix

  • if airway obstruction present:
    • if spirometry/PEFR indicate airway obstruction (FEV1 / FVC < 0.7) but Dx of asthma is only intermediate probability:
      • test for reversibility of obstruction or commence a trial of SABA with oral prednisolone 30 mg daily for two weeks, and if beneficial, Rx as for asthma
  • if no evidence of airway obstruction (FEV1 / FVC > 0.7)
    • if Dx of asthma is only intermediate probability, then refer for further Ix such as:
      • tests of airway responsiveness:
        • Methacholine PC20 challenge (the provocative concentration of methacholine required to cause a 20% fall in FEV1)
        • exercise challenge in untreated patients
      • tests for eosinophilic airway inflammation:
        • FENO (exhaled nitric oxide concentration)
        • Sputum eosinophil count
      • consider DDx such as:

clinical control of asthma

  • the Global Initiative for Asthma (GINA) defines clinical control as:
    • twice a week or less daytime symptoms or need for reliever
    • no limitation of actvities including exercise
    • no night time asthma symptoms
    • normal or near-normal lung function
    • no exacerbations

stepwise Rx of the adult asthmatic

step 1. mild asthma

step 2. mild asthma with frequent symptoms

  • for example:
    • exacerbations of asthma within past 2 years
    • symptomatic or needing to use SABA 3x a week or more
    • waking more than one night a week due to asthma
  • add a low dose inhaled corticosteroids preventer (ICS) such as (adult doses provided):
    • beclometasone 200mcg bd (eg. QVar)
    • budesonide 200mcg bd (eg. Pulmicort)
    • fluticasone 125mcg bd (eg. Flixotide)
    • mometasone 100mcg bd
    • ciclesonide 100mcg bd
  • for those unable to use ICS, consider:
    • sodium cromoglicate which is of some benefit in adults and is effective in children aged 5-12, or,
    • leukotriene receptor antagonists have been shown to have some beneficial clinical effect
      • especially useful for children under 5 years

step 3. poor control despite step 2 Mx

  • consider either:
    • increase ICS dose from low to medium dose (ie. double the dose), OR,
    • continue low dose ICS but add a long acting inhaled beta 2 adrenergic agonists (LABA), OR,
    • switch to a ICS-LABA FDC formulation, for example:
      • budesonide/eformoterol (eg. Symbicort turbuhaler 100/6 bd)
      • fluticasone/salmeterol (eg. Seretide MDI 50/25 bd or Seretide Accuhaler 100/50 bd)
      • fluticasone/eformoterol (eg. Flutiform 50/5 bd)

step 4. severe asthma

  • consider either:
    • if on medium dose ICS dose add a LABA, OR,
    • if on low dose ICS plus LABA, increase to medium dose ICS plus LABA OR,
    • if on ICS-LABA FDC formulation, consider higher dose FDC formulations such as
      • budesonide/eformoterol (eg. Symbicort turbuhaler 200/6 bd)
      • fluticasone/salmeterol (eg. Seretide MDI 100/25 bd or Seretide Accuhaler 200/50 bd)
      • fluticasone propionate - eformoterol fumarate dihydrate (eg. Flutiform 100/10 bd)

future potential medications

references

asthma.txt · Last modified: 2019/05/17 08:41 by gary1