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Management

• Overview
• Diagnosing
• Assessment
  • Peak Flow
  • Lung Function
  • Spirometry
  • Airway Responsiveness
• Signs & Symptoms
• Asthma control
• Classification
• Education
• Risk Factors

Assessment

Spirometry tests

• FEV₁ and forced vital capacity (FVC): the recommended method of measuring airflow limitation and reversibility to establish a diagnosis of asthma
• The degree of FEV₁ reversibility that indicates a diagnosis of asthma is generally accepted as ≥12% (or ≥200 ml) from the pre-bronchodilator value. However, as most patients do not exhibit reversibility at each assessment, particularly those on treatment, the test lacks sensitivity (repeated testing at different visits is advised)
• Spirometry is reproducible, but effort-dependent. Therefore, proper instructions on how to perform the forced expiratory maneuver must be given to patients, and the highest value of three recordings taken
• Ethnic differences in spirometric values have been demonstrated, and the normal range of values is wider and predicted values are less reliable in subjects <20 years and >70 years of age
• Many lung diseases may result in reduced FEV₁. A useful assessment of airflow limitation is the ratio of FEV₁ to FVC. This ratio is normally >0.75 to 0.80, and possibly >0.90 in children.

Any values less than these suggest airflow limitation.

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