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Reduced expiratory variability index (EVI) is associated with controller medication withdrawal and symptoms in wheezy
Ville-Pekka Seppä1, Marita Paassilta2,3, Juho Kivistö2,3
1Revenio Research Ltd., Vantaa, Finland.
Insights
Expiratory variability index (EVI) measured by impedance pneumography (IP) shows potential for routine lung function testing in young children with wheeze. Lower EVI in patients indicates airway obstruction, especially after medication withdrawal.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Biomedical Engineering
Background:
- Young children lack routine lung function testing methods for asthma diagnosis and monitoring.
- Reduced tidal breathing variability, measured by impedance pneumography (IP), is a potential indicator of airway obstruction.
- The expiratory variability index (EVI) is a novel metric derived from IP.
Purpose of the Study:
- To assess the discriminative capacity of EVI between healthy children and those with recurrent wheeze.
- To evaluate the association between EVI and parentally reported obstructive symptoms.
- To determine the measurement success rate of EVI in young children.
Main Methods:
- Sixty-eight young patients (1.0-5.6 years) with recurrent obstructive bronchitis and 40 healthy controls (1.0-5.9 years) were included.
- EVI was measured using IP at home during sleep before and after a three-month inhaled corticosteroid (ICS) treatment.
- Parental reports of bronchodilator use and airway infection were collected.
Main Results:
- EVI was significantly lower in patients compared to controls, indicating airway obstruction.
- A significant reduction in EVI was observed within patients 4 weeks after ICS withdrawal.
- Lower EVI at 4 weeks correlated with parental need for bronchodilator use, and measurement success rate was 94%.
Conclusions:
- EVI effectively differentiates between healthy children and those with recurrent wheeze.
- EVI decreases further after controller medication withdrawal, particularly with perceived wheeze symptoms.
- IP-derived EVI holds promise as a feasible tool for routine lung function assessment in young children with wheeze.
Background:
Lung function testing is an essential part of diagnostic workup and monitoring of asthma, but young children are lacking easy, routine testing methods. However, recent discoveries show reduced tidal breathing variability measured using impedance pneumography (IP) at home during sleep as a sign of airway obstruction. In this study, we assessed (a) the discriminative capacity of expiratory variability index (EVI) between healthy controls and young children with recurrent wheeze on-and-off controller medication, (b) association between EVI and parentally perceived obstructive symptoms (need for bronchodilator) and (c) measurement success rate.
Methods:
We included 68 patients (aged 1.0-5.6) and 40 healthy controls (aged 1.0-5.9 years). The patients were prescribed a three-month inhaled corticosteroid (ICS) treatment due to recurrent obstructive bronchitis. We measured EVI using IP at home at the end of the treatment (0W) and 2 (2W) and 4 (4W) weeks after ICS withdrawal.
Results:
EVI was higher in controls than in patients, and significant within-patient reduction occurred at 4W as compared to 2W or 0W. Area under curve of the ROC curve (controls vs all patients) at 4W was 0.78 (95% CI 0.70-0.85). Children who were administered bronchodilator by parental decision had lower EVI than those without bronchodilator need at 4W, but not at 0W or 2W. Patients with parent-reported airway infection, but no bronchodilator need, had normal EVI. Measurement success rate was 94%.
Conclusion:
EVI was lower in patients than in controls and it reduced further after controller medication withdrawal, especially in the presence of parentally perceived wheeze symptoms. This technique shows a significant potential for routine lung function testing of wheezy young children.
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