Asthma Knowledge Centre
Assessment
Measurement of airway responsiveness
This information is taken from the revised GINA Report, Global Strategy for Asthma Management and Prevention (2007), available on the Global Initiative for Asthma (GINA) website. Please refer to the full guideline document for more detailed information.
Measurement of airway responsiveness. For patients with symptoms consistent with asthma, but normal lung function, measurements of airway responsiveness to direct airway challenges such as inhaled methacholine and histamine or indirect airway challenges such as inhaled mannitol1 or exercise challenge may help establish a diagnosis of asthma2. Measurements of airway responsiveness reflect the “sensitivity” of the airways to factors that can cause asthma symptoms, sometimes called “triggers,” and the test results are usually expressed as the provocative concentration (or dose) of the agonist causing a given fall (often 20%) in FEV1 (Figure 2-3). These tests are sensitive for a diagnosis of asthma, but have limited specificity3. This means that a negative test can be useful to exclude a diagnosis of persistent asthma in a patient who is not taking inhaled glucocorticosteroid treatment, but a positive test does not always mean that a patient has asthma4. This is because airway hyperresponsiveness has been described in patients with allergic rhinitis5 and in those with airflow limitation caused by conditions other than asthma, such as cystic fibrosis6, bronchiectasis, and chronic obstructive pulmonary disease (COPD)7.
References:
1. Brannan JD, Anderson SD, Perry CP, Freed-Martens R, Lassig AR, Charlton B. The safety and efficacy of inhaled dry powered mannitol as a bronchial provocation test for airway hyperresponsiveness: a phase 3 comparison study with hypertonic (4.5%) saline. Respiratory research 2005; 6:144.
2. Cockcroft DW. Bronchoprovocation methods: direct challenges. Clin Rev Allergy Immunol 2003;24(1):19-26.
3. Cockcroft DW, Murdock KY, Berscheid BA, Gore BP. Sensitivity and specificity of histamine PC20 determination in a random selection of young college students. J Allergy Clin Immunol 1992;89(1 Pt 1):23-30.
4. Boulet LP. Asymptomatic airway hyperresponsiveness: a curiosity or an opportunity to prevent asthma? Am J Respir Crit Care Med 2003;167(3):371-8.
5. Ramsdale EH, Morris MM, Roberts RS, Hargreave FE. Asymptomatic bronchial hyperresponsiveness in rhinitis. J Allergy Clin Immunol 1985;75(5):573-7.
6. van Haren EH, Lammers JW, Festen J, Heijerman HG, Groot CA, van Herwaarden CL. The effects of the inhaled corticosteroid budesonide on lung function and bronchial hyperresponsiveness in adult patients with cystic fibrosis. Respir Med 1995;89(3):209-14.
7. Ramsdale EH, Morris MM, Roberts RS, Hargreave FE. Bronchial responsiveness to methacholine in chronic bronchitis: relationship to airflow obstruction and cold air responsiveness. Thorax 1984;39(12):912-8.