Forced Oscillation Technique (FOT) and spirometry in school aged children with stable asthma

Abstract

<b>Introduction:</b> Spirometry is widely used in pulmonary function testing in asthma, but remains challenging in young children. FOT is a non-invasive lung function test that does not require forced expiration thus may be more suitable for young children. <b>Aims:</b> To investigate the association of the Rrs5 to traditional measures of lung function from spirometry in children attending the asthma clinic. <b>Methods:</b> Children 5-16 years performed FOT with TremoFlo, using frequency range5-37Hz. Tests with 3 acceptable recordings were included. Spirometry was performed with a MicroLab spirometer. We compared the resistance at 5 (Rrs5) from FOT with FEV1, FVC, and FEV1/FVC Z-scores from spirometry. <b>Results:</b> Acceptable FOT and spirometry measurements were available for 146 children. The participants were divided into 3 groups according to objective evidence for asthma diagnosis. Group A: asthma with complete evidence (n=56), group B: asthma with incomplete evidence (n=66) and group C: suspected asthma with no evidence (n=24). In group A, the strongest correlation of Rrs5 was with FEV1/FVC (r= -0.497) followed by FEV1 (r= -0.465) (p-value&lt;0.05 for both). However, no correlation was noted between the Rrs5 and the FVC Z-scores. Conversely, in groups B and C no correlation was observed between Rrs5 Z-scores and any of the spirometry Z-scores. <b>Conclusion:</b> Despite the strong correlation noted between the Rrs5, FEV1, and FEV1/FVC in children with well-defined asthma, there were no similar relationships in children where asthma diagnosis was less certain. This suggests that the two techniques may reflect different aspects of the pathophysiological changes in childhood asthma.