Spirometry and its role in diagnosing children’s asthma

• 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

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

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

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

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

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

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:

• Interpretation of lung function tests – a step by step guide¹⁷ – this book provides guidance on the reporting of pulmonary function tests, including illustrative cases and sample reports.
• Spirometry Calculator from the Lung Foundation (also available on Medical Director GP software under the Healthshare sidebar).

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