Expiratory variability index (EVI) is associated with asthma risk, wheeze and lung function in infants with recurrent respiratory symptoms

TL;DR

This study demonstrates that the expiratory variability index (EVI), measured via impedance pneumography during sleep, correlates with lung function, asthma risk, and wheezing in infants with recurrent respiratory symptoms, offering a non-invasive testing method.

Contribution

The paper introduces EVI measurement using impedance pneumography as a novel, non-invasive lung function assessment tool for infants with respiratory issues.

Findings

Lower EVI correlates with reduced lung function.

Lower EVI is associated with higher asthma risk.

EVI is not related to nasal congestion.

Abstract

Recurrent respiratory symptoms are common in infants but the paucity of lung function tests suitable for routine use in infants is a widely acknowledged clinical problem. In this study we evaluated tidal breathing variability (expiratory variability index, EVI) measured at home during sleep using impedance pneumography (IP) as a marker of lower airway obstruction in 36 infants (mean age 12.8 [range 6-23] months) with recurrent respiratory symptoms. Lowered EVI was associated with lower lung function (VmaxFRC), higher asthma risk, and obstructive symptoms, but not with nasal congestion. EVI measured using IP is a potential technique for lung function testing in infants.