[Application of interrupter resistance pulmonary function testing in the diagnosis of asthma in preschool children: a single-center study].

Objectives: To investigate the value of interrupter resistance (Rint) pulmonary function testing in the diagnosis of asthma in preschool children, and to compare the significance of Rint pulmonary function testing versus impulse oscillometry (IOS) in the diagnosis of asthma.

Methods: A prospective study was conducted among 108 children with recurrent wheezing, aged 4 to <6 years, who were admitted from July 2022 to November 2023. According to the treatment outcome, they were divided into an asthmatic group (61 children) and a non-asthmatic group (47 children). Rint pulmonary function parameters and IOS parameters were analyzed for both groups, and the two tests were compared in terms of feasibility and diagnostic value.

Results: Compared with the non-asthmatic group, the asthmatic group had significantly higher percentage of actual measured value to predicted value for Rint and percent changes in the measured value and predicted value of Rint (P<0.05). The receiver operating characteristic curve analysis showed that the percent change in the predicted value of Rint had an optimal cut-off value of 32.0% in the diagnosis of asthma in preschool children, with an area under the curve (AUC) of 0.705, a sensitivity of 41.0%, and a specificity of 91.5% (P<0.05). In terms of the degree of completion, 18 children (16.7%) failed to complete the IOS test, but they could successfully complete Rint pulmonary function testing with good quality control. Rint pulmonary function testing and IOS had a similar area under the curve in the diagnosis of asthma in preschool children (P>0.05).

Conclusions: Rint pulmonary function testing can be used to assist in the diagnosis of asthma in preschool children, with a similar diagnostic value to IOS and a relatively high level of feasibility. A percent change of ≥32% in the predicted value of Rint in the bronchial dilation test can be used as a cut-off value for the diagnosis of asthma in preschool children.