Asthma Management Handbook

Assessing lung function in children 6 years and over


In children able to perform spirometry, measure bronchodilator reversibility by performing spirometry before and after giving inhaled rapid-onset beta2 agonist bronchodilator (e.g. 4 puffs of salbutamol 100 mcg/actuation) by metered-dose inhaler and spacer.


If reliable equipment and appropriately trained staff are available, spirometry can be performed in primary care. If not, refer to an appropriate provider such as an accredited respiratory function laboratory.

Most children aged 6 and older can perform spirometry reliably.

Airflow limitation is defined as reversible (i.e. bronchodilator response is clinically important) if FEV1 increases by ≥12%.

How this recommendation was developed


Based on clinical experience and expert opinion (informed by evidence, where available).

Operators who perform spirometry should receive comprehensive training to ensure good quality.

How this recommendation was developed


Based on clinical experience and expert opinion (informed by evidence, where available).

More information

Spirometry in children

Measuring lung function in young children is difficult and requires techniques that are not widely available.1 Generally, spirometry cannot be performed to acceptable standards in children younger than 4–5 years.2

Some older children cannot perform spirometry either. However, children who are unable to perform spirometry satisfactorily on their first visit are often able to perform the test correctly at the next visit.2

Spirometry is poor at discriminating between children with asthma and those with airway obstruction due to other conditions.1

Normal spirometry in a child, especially when asymptomatic, does not exclude the diagnosis of asthma.1 FEV1 is often normal in children with persistent asthma.1

Reduced FEV1 alone does not indicate that a child has asthma, because it may be seen with other lung diseases (or be due to poor spirometric technique).

A significant increase in FEV1 (>12% from baseline) after administering a bronchodilator (e.g. 4 puffs of salbutamol 100 mcg/actuation) indicates that airflow limitation is reversible and supports the diagnosis of asthma. In children with asthma, it is also predictive of a good lung function response to inhaled corticosteroids.1 However, an absent response to bronchodilators does not exclude asthma.1

Bronchial provocation (challenge) tests in children

Clinical assessment is more sensitive for confirming the diagnosis of asthma than tests for airway hyperresponsiveness.

The main roles of bronchial provocation (challenge) tests of airway hyperresponsiveness (airway hyperreactivity) are to confirm or exclude asthma as the cause of current symptoms, including exercise-associated respiratory symptoms such as dyspnoea or noisy breathing. 34

Challenge tests are performed in accredited lung function testing laboratories. These tests are usually difficult to perform in children under 8 years of age because they involve repeated spirometry tests.

If challenge testing is needed, consider referring to a paediatric respiratory physician for investigation, or discussing with a paediatric respiratory physician before selecting which test to order.

Do not test during a respiratory infection, or initiate inhaled corticosteroid treatment a few weeks before challenge testing, because these could invalidate the result.

Bronchial provocation tests of airway hyperresponsiveness include:

  • exercise challenge test5
  • mannitol challenge test67
  • methacholine challenge test.8, 9
Roles of other lung function tests in diagnosing asthma in children

Peak expiratory flow meters in asthma diagnosis

Variability in lung function based on serial home measures of peak expiratory flow and FEV1 shows poor concordance with disease activity in children.1

Using a peak flow meter to measure peak expiratory flow in children does not reliably rule the diagnosis of asthma in or out.1

Newer tests under investigation

Impulse oscillometry, tests of specific airways resistance, and measurements of residual volume are being investigated for use in asthma diagnosis and management,10, 11 but their availability is mainly restricted to specialist and research centres.1



  1. British Thoracic Society (BTS), Scottish Intercollegiate Guidelines Network (SIGN). British Guideline on the Management of Asthma. A national clinical guideline. BTS, SIGN, Edinburgh, 2012. Available from:
  2. Johns DP, Pierce R. Pocket guide to spirometry. 3rd edn. McGraw Hill, North Ryde, 2011.
  3. Anderson SD. Bronchial challenge tests: usefulness, availability and challenges. Breathe. 2011; 8: 53-60. Available from:
  4. Cockcroft DW. Direct challenge tests: airway hyperresponsiveness in asthma: its measurement and clinical significance. Chest. 2010; 138(2 Suppl): 18S-24S. Available from:
  5. Anderson SD, Pearlman DS, Rundell KW, et al. Reproducibility of the airway response to an exercise protocol standardized for intensity, duration, and inspired air conditions, in subjects with symptoms suggestive of asthma. Respir Res. 2010; Sept 1: 120. Available from:
  6. Barben J, Roberts M, Chew N, et al. Repeatability of bronchial responsiveness to mannitol dry powder in children with asthma. Pediatr Pulmonol. 2003; 36: 490-4. Available from:
  7. Kersten ET, Driessen JM, van der Berg JD, Thio BJ. Mannitol and exercise challenge tests in asthmatic children. Pediatr Pulmonol. 2009; 44: 655-661. Available from:
  8. Liem JJ, Kozyrskyj AL, Cockroft DW, Becker AB. Diagnosing asthma in children: what is the role for methacholine bronchoprovocation testing?. Pediatr Pulmonol. 2008; 43: 481-9. Available from:
  9. Carlsten C, Dimich-Ward H, Ferguson A, et al. Airway hyperresponsiveness to methacholine in 7-year-old children: sensitivity and specificity for pediatric allergist-diagnosed asthma. Pediatr Pulmonol. 2011; 46: 175-178. Available from:
  10. Child F. The measurement of airways resistance using the interrupter technique (Rint). Paediatr Respir Rev. 2005; 6: 273-7. Available from:
  11. Oostveen E, MacLeod D, Lorino H, et al. The forced oscillation technique in clinical practice: methodology, recommendations and future developments. Eur Respir J Supplement. 2003; 22: 1026-41. Available from: