Article
The Challenge of Assessing Lung Function in Preschool Children
Ethan Wilson, M.Sc., B.Sc. • November 26, 2025

Asthma is the most prevalent respiratory disease in children, affecting ~10% of children across the world (Global Asthma Report) (1). Therefore, assessing lung function in children is essential—especially for those showing signs of persistent coughing, wheezing, or shortness of breath. But when it comes to preschool-aged children (typically ages 3–5), evaluating their lung function isn't as straightforward as it is for older children and adults.


One of the gold-standard tools in respiratory medicine, spirometry, is often unreliable in this age group. This gap poses a real challenge for clinicians and can delay the accurate diagnosis and management of conditions like asthma.


Why Spirometry Doesn’t Work Well in Preschoolers


  • Cooperation and Comprehension - Spirometry requires a child to
  • Seal their lips tightly around a mouthpiece
  • Take a deep breath in
  • Blow out as hard and as fast as they can for several seconds


This sequence is unnatural and therefore challenging for many preschoolers, who may not fully understand or follow instructions consistently (2, 3). The result? Inaccurate, incomplete, or unreliable data.


  • Poor Reproducibility

Even if a young child manages to perform the test once, repeating it with the same effort and technique is a major hurdle. Reproducibility and therefore reliability is often lacking in this age group (3, 4).


  • Lack of Normative Data

Even when good-quality spirometry is achieved, there’s limited reference data for children under 6 (2). This makes it hard to interpret whether the results are truly normal or not.


 What Are the Consequences?


The inability to perform reliable spirometry in preschoolers leads to several clinical consequences:

  • Delayed or missed diagnosis: Without objective lung function data, diagnosing asthma or other lung diseases becomes more subjective and error-prone.
  • Over-treatment or under-treatment: Children may be prescribed medications they don't need—or may not receive treatment they urgently require.
  • Poor disease monitoring: Clinicians must rely more heavily on symptoms alone when the child has an appointment, which can be vague or misleading due to recall issues.



Moving Forward: Bridging the Gap


To improve respiratory care in preschoolers, we need:


  • More research into child-friendly lung function tests
  • Broader access to pulmonary function tests and tools that enable lung function tests in this age group
  • Better training and protocols for performing spirometry in young children
  • More normative data for interpreting results in this age group



Final Thoughts


The preschool years are a critical window for identifying and managing respiratory issues like asthma. Yet our tools for evaluating lung function aren’t always up to the task.


While clinicians do their best with clinical judgment and symptom tracking, the lack of reliable objective testing in this age group remains a significant gap in paediatric respiratory care. Continued innovation, research, and advocacy are key to closing it.


 

  1. 1Yuan L, Tao J, Wang J, She W, Zou Y, Li R, Ma Y, Sun C, Bi S, Wei S, Chen H, Guo X, Tian H, Xu J, Dong Y, Ma Y, Sun H, Lv W, Shang Z, Jiang Y, Lv H, Zhang M. Global, regional, national burden of asthma from 1990 to 2021, with projections of incidence to 2050: a systematic analysis of the global burden of disease study 2021. eClinicalMedicine 80, 2025. doi: 10.1016/j.eclinm.2024.103051.
  2. Fuhlbrigge AL, Kitch BT, Paltiel AD, Kuntz KM, Neumann PJ, Dockery DW, Weiss ST. FEV1 is associated with risk of asthma attacks in a pediatric population. Journal of Allergy and Clinical Immunology 107: 61–67, 2001. doi: 10.1067/mai.2001.111590.
  3. Aurora P, Stocks J, Oliver C, Saunders C, Castle R, Chaziparasidis G, Bush A. Quality Control for Spirometry in Preschool Children with and without Lung Disease. Am J Respir Crit Care Med 169: 1152–1159, 2004. doi: 10.1164/rccm.200310-1453OC.
  4. Nève V, Edmé J, Devos P, Deschildre A, Thumerelle C, Santos C, Methlin C, Matran M, Matran R. Spirometry in 3–5‐year‐old children with asthma. Pediatric Pulmonology 41: 735–743, 2006. doi: 10.1002/ppul.20389.


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Lazova S , Priftis S , Petrova G , Naseva E , Velikova T . MMEF25-75 may predict significant BDR and future risk of exacerbations in asthmatic children with normal baseline FEV1. Int J Physiol Pathophysiol Pharmacol 14: 33–47, 2022. Kwon DS , Choi YJ , Kim TH , Byun MK , Cho JH , Kim HJ , Park HJ . FEF25-75% Values in Patients with Normal Lung Function Can Predict the Development of Chronic Obstructive Pulmonary Disease. Int J Chron Obstruct Pulmon Dis 15: 2913–2921, 2020. doi: 10.2147/COPD.S261732. Jo YS , Kim SK , Park SJ , Um S-J , Park Y-B , Jung KS , Kim DK , Yoo KH . Longitudinal change of FEV1 and inspiratory capacity: clinical implication and relevance to exacerbation risk in patients with COPD. Int J Chron Obstruct Pulmon Dis 14: 361–369, 2019. doi: 10.2147/COPD.S189384. Peak expiratory flow HealthLink BC [Online]. [date unknown]. https://www.healthlinkbc.ca/healthwise/peak-expiratory-flow [2 Oct. 2025]. 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