Wheezing in infants and children less than 3 years of age children is a frequent feature that might be difficult to diagnose when only the caregivers reporting is available. Indeed, in this age group the usual reversible flow limitation measure during pulmonary function testing (PFT) is missing because PFT techniques require the full patient cooperation to perform respiratory tests. Infants PFTs have been developed to measure the same indexes than those measured in adults, but they are difficult to set-up and require medication- induced sleep during day time. However, when flow limitation is sufficient it can be detected during tidal breathing as measured during spirometry using pneumotachograph (PNT). In this test, the tidal breathing flow-volume (TBFV) loop is recorded and studied using different indices to assess the airflow limitation. But, there again, when addressing infants or very young children quiet breathing can only be achieved during sleep and medication- induced sleep necessary. 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. This technique has mainly been applied to monitor respiratory rate in intensive care settings, but recent technical advancements in IP signal processing and electrode placement strategy have enabled IP to be used for accurate non-invasive tidal flow signal measurement. Compared to direct PNT, high agreement in flow signal and TBFV indices has been demonstrated in young children as well as in infants, even during induced bronchoconstriction. Moreover, in overnight recordings at home, IP was found feasible for quantifying nocturnal TBFV variability in young children with lower respiratory symptoms. In this study, it was shown 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. Recently a study in Tampere University Hospital (TAUH) Allergy centre (Tampere, Finland, PSHP ethical committee code R14027, ClinicalTrials.gov code NCT02164968) finished collecting overnight TBFV using impedance pneumography on 70 young children with suspected asthma. The preliminary analysis of this data shows that the effect of asthma treatment can be seen in TBFV variability, but to assess the diagnostic capacity of this new method, healthy control sample should be collected. The technology developed by the Finnish medical device company Revenio Research Oy enables to evaluate the variability of the expiratory flow-volume curve. It is calculate as the expiration variability index (EVI) which is decreased in case of bronchoconstriction. In order to explore very young children (less than 3 years of age) unable to participate to any awake lung function test, we set-up a study aiming to: 1) establish reference value for EVI in healthy children 2 months to 3 years old 2) test the variation of EVI in case of acute disease with or without wheezing in this age group children. In this observational prospective multicenter study, we will include 110 asymptomatic healthy subjects to compute reference values of EVI. We will also include 35 previously healthy subjects who have developed an acute non wheezing disease such as fever, rhinitis, otitis or bronchitis to compare their EVI to the reference values. And finally, we will recruit 35 young subjects with an acute wheezing episode. All measurements will be performed at home by the parents, except for some wheezy children who could be hospitalized. It will be proposed to record 2 consecutive nights in healthy asymptomatic children in order to evaluate the night-to-night variability which has already shown to be small in older children. In this multicentre study 120 children will be recruited by the present study in France and the remaining 60 children in another English centre using the same design and technology. It is expected that only children with acute wheezing episode will have a significantly low EVI compare to the reference values established by this study.
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Expiration variability index (EVI) recorded during night sleep using impedance pneumography in 2 to 36 months old children
Timeframe: 48 hours