Spirometry and its role in diagnosing children’s asthma

Spirometry can be used to support a diagnosis of asthma for children aged 6 years and over, and for ongoing patient monitoring.

  • Medicinewise News | 19 February 2020
Spirometry and its role in diagnosing children’s asthma

Asthma diagnosis and treatment during the COVID-19 pandemic

Because of the COVID-19 pandemic, some aspects of asthma management, particularly around use of spirometry and nebulisers, may be more restricted at this time.

NPS MedicineWise currently recommends that patients:

  • keep taking their regular medicines
  • practice good hygiene and distancing to avoid infection
  • contact health professionals if they become ill.

NPS MedicineWise currently recommends that health professionals:

  • avoid spirometry or peak expiratory flow in patients with a fever or a worsening acute respiratory condition
  • only use spirometers with inline filters
  • avoid using nebulisers
  • note that salbutamol can only be bought in small quantities in pharmacies
  • keep themselves informed as the situation changes.

Find out more on our Asthma and COVID-19 page


Key points

  • Use spirometry to support a diagnosis of asthma for children aged 6 years and older
  • Consider involving trained nurses and allied health professionals to perform quality spirometry and manage GP workloads
  • Participate in training workshops or refresher courses to maintain competence to conduct spirometry
  • Refer patients to local respiratory laboratories if no spirometry is available on site

The right tool to support diagnosis but vastly underused

Diagnosis of asthma is problematic when it comes to children, as the symptoms of wheezing, breathlessness or cough may be due to other conditions, such as upper airway dysfunction, bronchitis and habit-cough syndrome.1 Spirometry, in addition to physical examination and history taking, can be used to support a diagnosis of asthma for children aged 6 years and over,1 and for ongoing patient monitoring.2

Although younger children (aged 1–5) are often unable to do the test adequately for reliable results, most children aged 6 and older can perform spirometry reliably. If a provisional asthma diagnosis has been given, it is recommended to perform spirometry when the child is 6 years or more to confirm the diagnosis.1 Despite the importance of spirometry in the diagnosis of asthma, spirometry is vastly underused.3

Common themes that emerge from research about the underuse of spirometry in general practice and possible approaches to address these are outlined in the table below.

Table 1. Challenges for and possible approaches to improve use of spirometry in general practice


Possible approaches

Lack of time4

  • Refer the patient to a practice nurse skilled in spirometry (if available in the practice).5 A study from Scandinavia found that spirometry was more likely to be used in practices where doctors have adequate resources, such as support staff.6
  • Consider referring the patient to a spirometry laboratory.7 The Thoracic Society of Australia and New Zealand has a list of accredited respiratory laboratories.

No equipment to perform spirometry8,9

Lack of expertise/health professional confidence in spirometry for children8

  • Consider spirometry training: The National Asthma Council holds Spirometry Training workshops for GPs and practice nurses in cities and regional centres across Australia (free CPD accredited course).
  • Consider referring the patient to a spirometry laboratory.

Patient has poor technique or poor effort when performing spirometry.10

  • Inform children and carers that they may not get a reliable result the first time but they can become better at it. Children can do a practice run by blowing air to inflate a balloon.11
  • Show carers a video about spirometry.

Patient (or carer) reluctance to have a spirometry test

  • Reinforce that it is a non-invasive, painless test.2
  • Highlight the benefits of having a confirmed diagnosis.2
  • Follow patients up with text messages or calls to check if they have performed the spirometry after referral to a laboratory.
  • Provide patients with the NPS MedicineWise fact sheet Getting children ready for spirometry.
  • Set up recalls in prescribing software for patient follow-up.

Expert commentary

We are increasingly aware of the limitations of overreliance on parental report of asthma symptoms in children. Objective measures to confirm the diagnosis are crucially important. In addition to enhancing diagnostic accuracy, spirometry helps to guide initiation of preventer therapy and inform dose adjustments (stepping-up and stepping-down) over time.

Dr Danielle Wurzel


Getting the best results

Tests of acceptable quality are required for correct diagnosis. To achieve best results, children need to feel comfortable.9 It is essential to establish rapport with each child to obtain measurements without causing distress.12

Health professionals need to follow these steps.

  • Give patients test preparation instructions in advance.
    A patient fact sheet about preparing children for a spirometry test can be downloaded from the NPS MedicineWise website. Provide information about withholding periods for bronchodilator medicines if applicable. Watching videos about how spirometry works can help children mentally prepare for the test so they know what to expect.
    Spirometry in GP practice (adult patient)
    - Spirometry in a hospital/spirometry laboratory (child patient)
  • Instruct patients or carers about proper test performance.
    Acceptable test quality requires optimal patient performance, which in turn requires adequate coaching from the health professional administering the test. Advise parents or carers to encourage their child to practise breathing forcefully by blowing up balloons before their appointment.
  • Assess the acceptability and repeatability of test results according to international guidelines.13
    Although most children 6 years and over have the lung capacity to perform spirometry, poor technique or poor effort will result in falsely low measurements or misinterpreted peak-flow curves.10 If reliable results cannot be obtained from their first spirometry test, book another appointment and encourage the child and parent/carer to give it another go. The child is likely to perform the test better the second time round.

    Errors should also be noted, as they may affect test results. Common errors in spirometry with children include hesitation, premature finish, more than one breathing attempt, poor effort and coughing.3

Expert commentary

As with any test, spirometry must be conducted correctly to produce meaningful and clinically useful results. While spirometry is not difficult, operators must undertake specific training to be proficient in conducting and interpreting spirometry. Spirometry is a highly useful diagnostic and management adjunct that should be used routinely in the management of asthma for all children.

Dr Danielle Wurzel


Interpreting spirometry results for children

The FEV1 (forced expiratory volume in one second) to FVC (forced vital capacity) ratio should be evaluated according to age for the diagnosis of asthma. A significant increase in FEV1 (≥ 12% from baseline) after administering a bronchodilator (eg, 4 puffs of salbutamol 100 micrograms/actuation) indicates that airflow limitation is reversible and supports the diagnosis of asthma.1 Bronchodilator responsiveness for children with asthma is also predictive of a good lung function response to inhaled corticosteroids.1

Table 2. Spirometry results for children1


Normal response

Reduced or increased response

FEV1 alone

FEV1 is often normal for children.

Normal spirometry results, especially when asymptomatic, do not exclude the diagnosis of asthma. FEV1 can be normal for children with persistent asthma.

Reduced FEV1 alone does not indicate that a child has asthma, because it may be due to poor spirometry technique.

A reduced FEV1 may also be seen with other lung diseases.

Bronchodilator response

Lack of response to bronchodilators does not exclude asthma.

A significant increase in FEV1 (≥ 12% from baseline) after administering a bronchodilator (eg, 4 puffs of salbutamol 100 micrograms/actuation) indicates that airflow limitation is reversible and supports the diagnosis of asthma.

FEV1/FVC ratio

A reduced FEV1 to FVC ratio indicates expiratory airflow limitation.

Expert commentary

While not all children with asthma demonstrate significant bronchodilator response at all times, when present it confirms a diagnosis of asthma and enables objective assessment of severity. For example, higher bronchodilator responsiveness is a risk factor for severe asthma exacerbations.

Dr Danielle Wurzel

Spirometry requires training and experience

The Australian and New Zealand Society of Respiratory Science (ANZSRS) and Thoracic Society of Australia and New Zealand list the requirements for quality spirometry training in their position paper.14 These include:

  • a course of 10 hours duration, with a practical component delivered face-to-face, or
  • shortened courses of 4 hours specifically for interpretation of test results for GPs, and
  • attendance at refresher courses within the first 12 months of completion of the initial course, and every 3 years thereafter.

Courses may be face-to-face or online, and vary in duration, cost and accreditation status.

See the National Asthma Council’s Spirometry training workshops

Spirometry is a reimbursable procedure

On 1 November 2018, changes were made to MBS items for spirometry. These changes focused on improving quality requirements and increased rebates on these items to promote the use of spirometry testing.15

A new MBS item has been introduced (11505), which provides a higher rebate for office-based spirometry to confirm diagnosis of asthma, chronic obstructive pulmonary disease or other types of airway disease.

The existing MBS item 11506, which may be used to claim for a service that includes both pre- and post-bronchodilator spirometry, can now also be used to claim spirometry testing for assessing acute exacerbations of asthma, as well as monitoring of asthma and chronic obstructive pulmonary disease.


What to look for in a spirometer

When selecting a spirometer, consider factors such as:16

  • ease of use
  • accuracy (whether the machine can be calibrated or accurately validated)
  • whether it meets American Thoracic Society/European Respiratory Society spirometer performance criteria.13

Other features to consider may include real-time graphic display, print-out capability, compatibility with clinical software or animated incentives in software. Paediatric spirometry software programs may include cartoon games where the game is won if the child can produce a forced expiration.11

Expert commentary

There are many spirometers on the market. Variables to consider when choosing a spirometer include cost, portability, ease of user interface and need for calibration. It is usually preferable to purchase an auto-calibrating spirometer. Many spirometry suppliers will enable a trial before purchase and offer customer support. The linked resources provide a very useful guide to assist in choosing the best spirometer for your practice.

Dr Danielle Wurzel


Spirometry resources

A wide range of resources on spirometry are available from National Asthma Council Australia:

  • Spirometer Users’ and Buyers’ Guide – a guide to selecting a spirometer, including a summary of the specifications, features and suppliers of the main spirometers on the Australian market, plus general information about the measurement and application of spirometry in the primary care clinical setting.
  • Spirometry Handbook – an introductory guide for people involved in conducting and interpreting spirometry in primary care.
  • Pocket Guide to Spirometry, 3rd edition – detailed guide to spirometry, including what a spirometer is, how to use one, how to interpret test results and the different types of spirometers.
  • Spirometry training workshops – a range of asthma and respiratory education workshops for health professionals, including spirometry training for GPs and practice nurses.

Other useful resources include:


Expert reviewer

Dr Danielle Wurzel, MBBS (Hons), PhD, FRACP

Respiratory Consultant, Department of Respiratory and Sleep Medicine
Honorary Research Fellow, Murdoch Children’s Research Institute
Honorary Senior Fellow, Department of Paediatrics, University of Melbourne
Royal Children's Hospital, Melbourne



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