Background: There have been difficulties in applying spirometric tests to children of preschool age.

Methods: The feasibility of measuring lung function was examined in 652 children aged 3–6 years using dynamic spirometry with an animation programme and the guidelines approved by the European Respiratory Society.

Results: Data from 603 (92%) children with at least two acceptable forced expiratory manoeuvres were analysed; 408 (68%) achieved at least three acceptable manoeuvres. Children with only two acceptable manoeuvres were younger, shorter, and weighed less (p<0.001). The lower levels of lung function in this group were partly explained by body size. 63% of those with three acceptable manoeuvres had a difference of ≤5% between the highest and second highest forced expiratory volume in 1 second (FEV₁); when a difference of ≤10% was applied, 91% of the children were included. A similar trend was seen for forced vital capacity (FVC). The acceptability and reproducibility increased with increasing age, and levels of lung function increased linearly with age. The linear regression model showed that standing height was a satisfactory predictor of lung function; the explained fraction of variance (R²) was 59% for FEV₁. Most FVC manoeuvres in children older than 3 years were acceptable and reproducible.

Conclusions: Spirometric testing is feasible in preschool children and may be useful for both clinical practice and research. This study may fill the deficiency in reference values for European preschool children.