Lung function testing and inflammation markers for wheezing preschool children: A systematic review for the EAACI Clinical Practice Recommendations on Diagnostics of Preschool Wheeze

Background Preschool wheeze is highly prevalent; 30%-50% of children have wheezed at least once before age six. Wheezing is not a disorder; it is a symptom of obstruction in the airways, and it is essential to identify the correct diagnosis behind this symptom. An increasing number of studies provide evidence for novel diagnostic tools for monitoring and predicting asthma in the pediatric population. Several techniques are available to measure airway obstruction and airway inflammation, including spirometry, impulse oscillometry, whole-body plethysmography, bronchial hyperresponsiveness test, multiple breath washout test, measurements of exhaled NO, and analyses of various other biomarkers. Methods We systematically reviewed all the existing techniques available for measuring lung function and airway inflammation in preschool children to assess their potential and clinical value in the routine diagnostics and monitoring of airway obstruction. Results If applicable, measuring FEV1 using spirometry is considered useful. For those unable to perform spirometry, whole-body plethysmography and IOS may be useful. Bronchial reversibility to beta2-agonist and hyperresponsiveness test with running exercise challenge may improve the sensitivity of these tests. Conclusions The difficulty of measuring lung function and the lack of large randomized controlled trials makes it difficult to establish guidelines for monitoring asthma in preschool children.