ABSTRACT
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.
ABSTRACT
BACKGROUND: Small airway dysfunction (SAD) in asthma can be measured by impulse oscillometry (IOS). Usually, the reactance should decrease with decreases in frequency oscillation. Sometimes an upward shift of the curve at low frequencies can be observed together with lower than expected reactance values. The actual value of the reactance at 5 Hz (X5) is calculated by the Sentry Suite application of the Jaeger Master screen iOS system™, providing the corrected X5 parameter (CX5). Our hypothesis is that correction of X5 is common in persistent asthma and it correlates better than X5 with the IOS parameters for evaluating SAD. METHODS: In this transversal study, we evaluated 507 children (3-18 years old) using IOS-spirometry (Sentry Suite, Vyntus®). Resistance of all airways (R5), reactance area (AX), resonant frequency (Fres), X5, CX5, difference between R5 and R20 (D5-20), and spirometry parameters were analyzed. Reactance inversion and CX5 prevalence by age range was determined. The mean IOS-Spyrometry values in children with and without CX5 were compared, and correlations with each IOS-spirometry parameter in the age groups were performed. RESULTS: CX5 was found in 83.5% of preschool children, 66.2% of schoolchildren, and 43.3% of adolescents (p < 0.001). The means of R5, AX, and D5-20 were significantly higher and FEV1 was significantly lower in children with CX5 (p < 0.05). In all ages, CX5 correlated better than X5 with IOS-spirometry parameters. CONCLUSION: Reactance inversion and CX5 are frequent in asthmatic children, decrease with age, and correlate more closely than X5 with other IOS-spirometry parameters for evaluating SAD.
Subject(s)
Asthma , Adolescent , Asthma/diagnosis , Child , Child, Preschool , Forced Expiratory Volume , Humans , Lung , Oscillometry , Respiratory Function Tests , SpirometryABSTRACT
INTRODUCTION: Impulse oscillometry (IOS) is useful for measuring lung function in preschool children. Our objec tive was to describe the alterations and evolutionary profile of IOS in asthmatic children under 6 years of age after one year of follow-up. PATIENTS AND METHOD: 62 preschoolers performed IOS at the begin ning of the study and after one year. The proportion of altered IOS and bronchodilator response (BR +) at both times was compared, in addition to sub-analysis according to asthma control and presence of atopy. For the statistical analysis, we used McNemar's %2 and the Student's t-test with a 5% a error. RESULTS: The initial IOS was altered in 80.6% and in 64.5%% after one year (p = 0.04). 77.4% of the children presented BR+ at the beginning of the study and 83.9% after one year. The uncontrolled asthma group presented a significant improvement in the X5 and D5-20 means, but the controlled asthma group did not. In atopic patients, only uncontrolled asthmatics improved X5, AX, and D5-20. CONCLUSION: IOS shows alterations in a high percentage of preschoolers with uncontrolled asthma, which decreases significantly at one year, but remains altered and with BR + in most children. Ad ditional studies are required to identify different preschool asthma phenotypes and their evolution with treatment.
