Tidal flow variability measured by impedance pneumography relates to childhood asthma risk

Abstract

Lung function variability is a fundamental feature of asthma but has been difficult to quantify in children due to methodological limitations. We assessed the feasibility and clinical implications of overnight flow variability measurement at home using impedance pneumography in young children.44 children aged 3-7 years with recurrent or persistent lower airway symptoms were recruited. Patients were divided into high- or lower-risk groups (HR and LR groups) based on their risk of asthma (modified Asthma Predictive Index), and a third group was formed of children who had a history of wheeze and who were treated with inhaled corticosteroids (ICS group). Tidal volume and the derived flow were recorded through skin electrodes using impedance pneumography at home during sleep. Quantities describing overnight change in expiratory flow-volume minimum curve shape correlation (CSRmin) and respiratory chaoticity (minimum noise limit (NLmin)) were derived.Recordings were successful in 34 children. CSRmin differed between the HR and LR groups (p=0.002) and between the HR and ICS groups (p=0.003), indicating a stronger change in flow profile shape in the HR group. NLmin differed between the HR and LR groups (p=0.014), indicating momentarily lowered chaoticity in the HR group.Impedance pneumography was found feasible for quantifying nocturnal lung function variability and the measured variability was associated with risk of asthma in young children.

Measurement of tidal breathing flows in infants using impedance pneumography

“…However, for deriving complete TBFV curves by IP, high linearity with the flow signal is required. In preschool children, we have previously confirmed the validity of IP for recording tidal airflow profiles [13], and found that tidal breathing variability assessed by IP during home recordings is related to childhood asthma risk [14]. We have now found the linearity of IP to be comparable and therefore satisfactory to also study similar clinical correlates in infants.…”

“…Recordings of longer duration also enable the calculation of more robust measures of tidal airflow profiles than the conventional TBFV parameters, as well as complex indices of flow variability [38]. By using nocturnal recordings with IP, we demonstrated that preschool children with a high risk of asthma present with an increased variation of tidal flow profile shape, and momentarily lowered chaoticity, compared to children with a lower risk of asthma [14]. Similar ambulatory applications could be envisioned for infants, but so far no data are available.…”

“…High agreement has been demonstrated in relative flow signal and TBFV indices between IP and direct PNT in young children, even during induced bronchoconstriction [13]. Moreover, in overnight recordings at home, IP was found to be feasible for quantifying nocturnal TBFV variability in young children with lower respiratory symptoms [14]. There are currently no previous data using IP in tidal flow measurement in infants with or without airway obstruction.…”

Fundamentals, Recent Advances, and Future Challenges in Bioimpedance Devices for Healthcare Applications

“…TIP has been used to measure lung volume changes [255], to evaluate respiratory condition during normal and deep breathing [256], the assessment of asthma risk from tidal flow variability [257], sleep disorders [258], energy expenditure estimation [259], or even the detection of body posture changes [260]. Another application of TIP is the gating of positron-emission tomography (PET) and singlephoton emission computed tomography (SPECT) images.…”

Mini review shows that structured light plethysmography provides a non‐contact method for evaluating breathing patterns in children

“…Therefore, tidal breathing flow volume measurements have been used instead to characterise lung functions in infants and young children . A number of techniques have been developed that estimate tidal breathing from chest movements, such as respiratory inductive plethysmography , optoelectronic plethysmography or impedance pneumography . These techniques can provide useful information related to ventilatory effort or estimate changes in lung volumes.…”