Tidal breathing parameters in young children: Comparison of measurement byrespiratory inductance plethysmography to a facemask pneumotachograph system

The ratio of expiratory time at tidal peak flow to total expiratory time (t (ptef)/t(e)) correlates with conventional measures of airway obstruction. i t is usually assessed using a facemask and pneumotachograph system which ma y be poorly tolerated in young children and hence limits the usefulness of this technique. We therefore determined in young asthmatic children the acc uracy of rp,,di,, using an uncalibrated respiratory inductance plethysmogra ph (RIP), and compared the results with those from a racemask-pneumotachogr aph system. We also assessed whether age influenced the agreement between m easurements using the two devices. Forty-seven children aged between 1 mont h and 12 years were recruited. 39 were inpatients recovering from an acute wheezy episode, and 8 were recruited from the asthma clinic. All were recei ving bronchodilators. Tidal breathing parameters t(ptef)/t(e), the duty cyc le (t(l)/t(tot)), and respiratory rate were initially measured using the Re spitrace(R) alone and then simultaneously with both the Respitrace(R) and t he facemask-pneumotachograph system. Eight children did not tolerate the facemask, and in two others ii was impo ssible to analyze the Respitrace(R) trace due to artefacts. In the remainin g 37 children, the reliability coefficients and coefficients of variation o f the two techniques were similar. Similar values of t(i)/t(tot) and respir atory rate were obtained using the two devices. The mean t(ptef)/t(e) obtai ned using the Respitrace(R) was lower than with the iacemask-pneumotachogra ph system (P < 0.01), although this was age group-dependent (P < 0.05), as the difference was less apparent in the 1 to 2-year-old children than in ot her age groups. Application of the iacemask-pneumotachograph system did not significantly influence the results obtained using the Respitrace(R). We conclude that uncalibrated respiratory inductance plethysmography can me asure tidal breathing parameters as reliably as a facemask-pneumotachograph system in young asthmatic children, and is better tolerated than the pneum otachograph system. The results obtained using the two devices are not inte rchangeable. (C) 1999 Wiley-Liss, Inc.