Assessment of within-breath impulse oscillometry parameters in children with asthma

Reactance inversion in moderate to severe persistent asthma: low birth weight, prematurity effect, and bronchodilator response

INTRODUCTION

Reactance inversion (RI) has been associated with impaired peripheral airway function in persistent asthma. However, there is little to no data about the difference between asthmatic children with and without RI. This study aimed to detect clinical and lung function differences in moderate-severe asthmatic children with and without RI.

METHODS

This study was conducted between 2021 and 2022 in asthmatic school-age children. Impulse oscillometry (IOS) and spirometry were performed according to ATS/ERS standards.

RESULTS

A total of 62 patients, with a mean age of 8.4 years, 54.8% were males and were divided into three groups: group 1 (32.3%) with no RI, group 2 (27.4%) with RI but disappearing after bronchodilator test and group 3 (40.3%) with persistent RI after bronchodilator test. Children in groups 2 and 3 had significantly lower birth weights than in group 1. Group 2 had lower gestational age compared to group 1. FEV1 and FEF25-75 of forced vital capacity were significantly lower in groups 2 and 3. In group 3, R5, AX, R5-20, and R5-R20/R5 ratios were significantly higher. Bronchodilator responses (BDR) in X5c, AX, and R5-R20 were significantly different between groups and lower in group 3.

CONCLUSION

RI is frequently found in children with moderate-severe persistent asthma, particularly in those with a history of prematurity or low birth weight. In some patients, RI disappears after the bronchodilator test; however, it, persists in those with the worst pulmonary function. RI could be a small airway dysfunction marker.

Predictive Value of Impulse Oscillometry Combined with Fractional Expiratory Nitric Oxide Test for Asthma in Preschool Children

Objective

Prediction of asthma in preschool children is challenging and lacks objective indicators. The aim is to observe and analyze the variances between impulse oscillometry (IOS) and fractional expiratory nitric oxide (FeNO) in preschool children with wheezing, establish a joint prediction model, and explore the diagnostic value of combining IOS with FeNO in diagnosing asthma among preschool children.

Patients and methods

This study enrolled children aged 3-6 years with wheezing between June 2021 and June 2022. They were categorized as asthmatic (n=104) or non-asthmatic (n=109) after a 1-year follow-up. Clinical data, along with IOS and FeNO measurements from both groups, underwent univariate regression and multiple regression analyses to identify predictive factors and develop the most accurate model. The prediction model was built using the stepwise (stepAIC) method. The receiver operating characteristic curve (ROC), calibration curve, Hosmer-Lemeshow test, and decision curve analysis (DCA) were employed to validate and assess the model.

Results

During univariate analysis, a history of allergic rhinitis, a history of eczema or atopic dermatitis, and measures including FeNO, R5, X5, R20, Fres, and R5-R20 were found to be associated with asthma diagnosis. Subsequent multivariate analysis revealed elevated FeNO, R5, and X5 as independent risk factors. The stepAIC method selected five factors (history of allergic rhinitis, history of eczema or atopic dermatitis, FeNO, R5, X5) and established a prediction model. The combined model achieved an AUROC of 0.94, with a sensitivity of 0.89 and specificity of 0.88, surpassing that of individual factors. Calibration plots and the HL test confirmed satisfactory accuracy.

Conclusion

This study has developed a prediction model based on five factors, potentially aiding clinicians in early identification of asthma risk among preschool children.

[Value of fractional exhaled nitric oxide combined with impulse oscillometry in the diagnosis of asthma in preschool children]

OBJECTIVES

To evaluate the value of fractional exhaled nitric oxide (FeNO) combined with impulse oscillometry (IOS) in the diagnosis of asthma in preschool children, and to establish the optimal predictive model.

METHODS

A retrospective analysis was performed on 156 children with wheezing, aged 3-5 years, who were admitted from September 2019 to December 2020. These children were divided into an asthma group with 52 children and a non-asthma group with 104 children. The two groups were compared in terms of IOS parameters, FeNO, and clinical data. The multivariate logistic regression analysis was used to establish the optimal predictive model.

RESULTS

Compared with the non-asthma group, the asthma group had significantly higher total respiratory system impedance at 5 Hz (Z5), resistance of respiratory system at 5 Hz and 20 Hz (R5 and R20, respectively), resonance frequency, reactance area (AX), and FeNO and a significantly lower reactance difference at 5 Hz (P<0.05). The receiver operating characteristic (ROC) curve analysis showed that Z5, R5, R20, and FeNO had a certain value in the diagnosis of asthma (P<0.05). The multivariate logistic regression analysis established the optimal predictive model of R20+AX+FeNO, with an area under the ROC curve of 0.858 (P<0.05), a sensitivity of 78.8%, and a specificity of 76.9%.

CONCLUSIONS

FeNO combined with IOS is helpful for the diagnosis of asthma in preschool children, and the model of R20+AX+FeNO has a certain value in the diagnosis of asthma in these children.

Pediatric pulmonology year in review 2019: Physiology

Pulmonary physiologic assessments are critical for the care and study of pediatric respiratory disease. In 2019, there were numerous contributions to this topic in Pediatric Pulmonology.