Summary

Background: The forced oscillation technique is a non-invasive and effort-independent technique and is well suited for lung function measurement in young children. FOT[1] employs small-amplitude pressure oscillations superimposed on normal breathing. Therefore, it has the advantage over conventional lung function techniques in that it does not require patient cooperation for conducting respiratory maneuvers.

Objectives: To test the feasibility of the FOT test in preschool children and to compare the results to the commonly used spirometry before and after the administration of bronchodilator therapy.

Methods: Forty-six children (median age 4.9 years, range 1.8–18.3) attending the Pulmonary Clinic at Schneider Children's Medical Center tried to perform FOT and routine spirometry. Results were retrospectively analyzed. 

Results: Of the 46 children 40 succeeded in performing FOT and only 29 succeeded in performing simple spirometry. All but one of the 32 children aged 4 years and above (97%) could perform both tests. Nine of 14 children (64%) aged 4 and less could perform the FOT but only 3 (21%) could perform spirometry. Baseline values of respiratory resistance measured at 6 Hz (R6) negatively correlated with body length (r² = 0.68, P < 0.005). Twenty-four children performed both tests before and after bronchodilator therapy. A significant concordance was found between the measured responses to bronchodilators by FOT and spirometry (P < 0.01). Only one child had a negative response by FOT but a positive response by spirometry.

Conclusions: The FOT is a simple, non-invasive technique that does not require subject cooperation and thus can be utilized for measuring lung function in children as young as 2 years of age. Furthermore, the FOT was shown to reliably measure response to bronchodilator therapy.