Impedance Pneumography in Assessment of Asthma Control in Preschool Children

Lung function assessment of preschool children is hindered by their limited co-operation in conventional tests such as peak expiratory flow (PEF) or spirometry. However, indices derived from spontaneous tidal respiratory air flow and the shape of tidal expiratory flow-volume and flow-time curves relate to lung function and are easier to record even in young children. As a more advanced approach, the time dynamics and complexity properties of the tidal breathing flow volume (TBFV) signal have been analysed and found to relate to various respiratory conditions. Impedance pneumography (IP) is a method for measuring changes in the thoracic electrical impedance through skin electrodes, which varies as a function of lung aeration i.e. breathing. Recent technical advancements have enabled IP to be used for accurate non-invasive tidal flow signal measurement. Moreover, in overnight recordings at home, IP was found feasible for quantifying nocturnal TBFV variability in young children with lower respiratory symptoms, showing that preschool children with high risk of asthma present with increased variation of tidal flow profile shape, and momentarily lowered chaoticity, compared to children with lower risk of asthma. So far, there are no studies that have addressed the utility of IP to assess asthma control in young children with asthma. The purpose of this study is to investigate the utility of a commercially available IP device (VENTICA, Icare Finland, Finland) and IP-derived clinical indices in assessing the clinical control of asthmatic children receiving normal therapy in a longitudinal setting. The primary hypothesis is that TBFV variability quantified by IP is associated with disease control during management of young children with asthma. The secondary hypothesis is that TBFV variability quantified by IP predicts changes in disease control during management of young children with asthma.