Impedance Pneumography for Diagnosing and Monitoring Asthma in Young Children: A Systematic Review

Background: Impedance pneumography (IP) is a non-invasive technique for assessing tidal breathing in young children and enables home-based recordings without active patient cooperation. By deriving tidal breathing flow-volume (TBFV) curves and indices such as the expiratory variability index (EVI), IP has been proposed as a tool for identifying obstructive breathing patterns and monitoring airway function in early childhood. However, its clinical role in asthma and wheezing disorders has not been systematically evaluated. This review aimed to assess the evidence of IP in differentiating healthy children from those with asthma or recurrent wheeze, in reflecting treatment-related changes or acute bronchial obstruction, and in relation to other lung function tests. Methods: A systematic literature search of PubMed, Medline, Embase, and the Cochrane Library databases was conducted on 5 January 2026. Original studies using IP in children aged 0-7 years with asthma or wheeze were eligible. Study selection followed PRISMA guidelines, and risk of bias (RoB) was assessed using the Newcastle-Ottawa Scale (NOS). Due to substantial heterogeneity in study design, populations, and outcome measures, results were synthesized narratively. Results: Five studies were included, with a total of 376 participants aged 0.5-7.0 years. Three studies reported significantly lower EVI values and TBFV profile variation in children with asthma or recurrent wheeze compared with healthy controls. Two studies found an association between EVI and markers of airway obstruction. Changes in IP measures following inhaled corticosteroid treatment or medication withdrawal were reported, suggesting sensitivity to treatment-related changes. However, study quality was moderate to low, with small sample sizes, heterogeneous outcome definitions, and limited diagnostic validation. Conclusions: Current evidence suggests that IP-derived indices, particularly EVI, capture clinically relevant features of obstructive breathing patterns in young children and may be useful for longitudinal monitoring of airway function. However, evidence supporting a diagnostic role for IP in childhood asthma remains limited. Larger, independent, and methodologically robust studies are needed before IP can be integrated into routine clinical practice.