Spirometry – top tips part 1: for accurate performance

Spirometry is a common test used by healthcare professionals (HCPs) to diagnose asthma, chronic obstructive pulmonary disease (COPD) and other conditions that can affect a patient’s ability to breathe. It measures the volume of air exhaled at specific time points during complete exhalation.^[1][2]

This article is the first of two parts designed to support you in your understanding of spirometry. In this article, you’ll learn:

• what spirometry is
• why spirometry is important
• how to begin developing your skills in performing spirometry.

What is spirometry?

Spirometry remains an essential tool for the diagnosis, assessment and monitoring of respiratory conditions, particularly chronic obstructive pulmonary disease (COPD). During the COVID-19 pandemic, the Primary Care Respiratory Society (PCRS) recommended using peak expiratory flow rate (PEFR) measures with spirometry confirmation later however, now that regular testing has resumed PCRS no longer recommends this approach, instead spirometry confirmation of COPD is mandatory before any definitive communication with a patient that they have a COPD diagnosis.^[2]

Spirometry helps you to:^[3]

• differentiate between obstructive and restrictive lung diseases
• assess severity and progression of lung disease
• monitor the effectiveness of treatment
• confirm a diagnosis.

It is important to note that spirometry is just one part of the diagnostic process. HCPs will also consider areas such as clinical context, diagnostic tests and patient history to make an accurate diagnosis.^[4]

To ensure reliable results, spirometry should be conducted by trained and certified HCPs who meet the standards set by the Association for Respiratory Technology and Physiology (ARTP)^[5]

Preparation and best practice for performing spirometry

1. Preparing the Patient

Patient preparation is a crucial step in achieving valid, reproducible results. Providing a spirometry advice sheet ahead of the appointment helps patients understand how to prepare. Key instructions should include:^[6]

• avoid smoking for at least 24 hours before the test
• refrain from large meals prior to testing
• avoid vigorous exercise beforehand
• wear loose-fitting clothing for comfort and mobility.

2. Choosing the right spirometry type

Before testing begins, it’s important to select the appropriate spirometry method based on clinical need:^[7]

• baseline spirometry: used when a diagnosis is not yet established to assess lung function
• post-bronchodilator spirometry: used when baseline spirometry indicates obstruction, helping to diagnose conditions like asthma or COPD
• reversibility testing: can help differentiate asthma from COPD, although its reliability is limited and it may not always be necessary.

3. Preparing the equipment and environment

Proper test setup is essential. According to ARTP guidance, the following must be in place:⁶

• use of calibrated, CE-marked spirometer
• routine maintenance and biological control checks
• adherence to infection control protocols, including disposable bacterial/viral filters and single-use mouthpiece and clean nose clip.

If the test involves assessing bronchodilator reversibility, medications such as β₂-agonists or muscarinic antagonists may need to be withheld for a set period prior to testing. Any medications taken should be clearly recorded, along with the time relative to the test. Always consider the patient’s safety and clinical history when deciding whether medication withholding is appropriate.^[6]

4. Procedure

Once preparation is complete:^[6]

• start with relaxed blows, ask the patient to take a deep breath in, seal lips around the mouthpiece, and then blow out in a relaxed manner until completely empty
• take a deep breath in, seal lips around the mouthpiece, and then blow out as hard and fast as possible until completely empty (at least 6 seconds in adults)
• repeat until you have three acceptable and two repeatable efforts, as per ARTP standards.

Conclusion

Spirometry is a cornerstone of respiratory assessment in primary care when performed and interpreted correctly. Ensuring high test quality, understanding interpretation frameworks, and applying clinical judgment will significantly improve diagnosis and management of respiratory conditions.

To interpret spirometry effectively, HCPs must combine test results with a comprehensive understanding of the patient’s clinical picture. This includes their medical history, physical examination findings, and any additional investigations. Taking this holistic approach ensures more accurate diagnoses and better-informed management decisions.

[1] Spirometry and bronchodilator reversibility test. Available at: https://www.asthmaandlung.org.uk/symptoms-tests-treatments/tests/spirometry

[2] PCRS spirometry in primary care following the COVID-19 pandemic. Available at: https://www.pcrs-uk.org/sites/default/files/resource/2023-10-23-Position-Statement-Spirometry-in-Primary-Care.pdf

[3] Spirometry service: Venn primary care network. Available at: https://www.vennpcn.nhs.uk/spirometry-service-venn-primary-care-network.html#:~:text=Spirometry%20Test,disease%20(COPD)%20and%20asthma.

[4] Spirometry commissioning guidance. Available at: https://www.england.nhs.uk/wp-content/uploads/2020/03/spirometry-commissioning-guidance.pdf

[5] Spirometry standards. Available at: https://www.artp.org.uk/resources/spirometry-standards

[6] Performance of spirometry in adults. Available at: https://www.artp.org.uk/resources/spirometry_sop_2023

[7] A guide to performing quality assured diagnostic spirometry. Available at: https://www.brit-thoracic.org.uk/media/70454/spirometry_e-guide_2013.pdf