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Reactance inversion in moderate to severe persistent asthma: low birth weight, prematurity effect, and bronchodilator
Ramiro González Vera1, Alberto Vidal Grell2, José A Castro-Rodríguez3
1Clínica Las Condes, Santiago, Chile.
Insights
Reactance inversion (RI) is common in children with severe asthma, especially those born prematurely. Persistent RI indicates poorer lung function and may signal small airway dysfunction.
Area of Science:
- Pediatric Pulmonology
- Respiratory Medicine
- Asthma Research
Background:
- Reactance inversion (RI) is linked to impaired peripheral airway function in persistent asthma.
- Limited data exists on clinical and lung function differences between asthmatic children with and without RI.
Purpose of the Study:
- To identify clinical and lung function differences in moderate-to-severe asthmatic children with and without RI.
Main Methods:
- Conducted between 2021-2022 with school-aged asthmatic children.
- Utilized impulse oscillometry (IOS) and spirometry per ATS/ERS standards.
- Divided 62 patients into three groups: no RI, transient RI, and persistent RI.
Main Results:
- Children with RI (groups 2 and 3) had lower birth weights and gestational ages than those without (group 1).
- Groups 2 and 3 showed significantly lower FEV1 and FEF25-75.
- Persistent RI (group 3) correlated with higher R5, AX, R5-20, R5-R20/R5 values and lower bronchodilator responses.
Conclusions:
- RI is prevalent in moderate-to-severe persistent asthma, particularly in those with prematurity or low birth weight history.
- While RI can resolve post-bronchodilator, persistent RI is associated with worse pulmonary function.
- RI may serve as a marker for small airway dysfunction in pediatric asthma.
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.
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