Impedance pneumography to explore bronchial obstruction in young infants born moderate-late preterm: a cohort study

BACKGROUND: Wheezing, a symptom reflecting bronchial obstruction, is frequently reported in preterm-born infants. No objective and reliable tool is available to assert this diagnosis with minimal patient cooperation. Nocturnal tidal breathing measurements by impedance pneumography (IP) provide expiratory variability index (EVI) and the ratio of time to peak tidal expiratory flow to total expiration (tPTEF/tE) which are reduced in bronchial obstruction and may address this gap. AIMS: To evaluate the application of IP measurements in a cohort of preterm-born infants. METHODS: Home measurements were performed over two consecutive nights in infants (median (IQR) gestational age 34+4 weeks (33+1; 35+2)), around ages 3, 6 and 12 months. EVI and tPTEF/tE were derived from successful recordings (≥4 hours undisturbed). Measurements in term-born infants <14 months served as reference. RESULTS: In total 372 night-recordings were obtained from 97 preterm infants. Success rates were 15%, 93% and 91% in infants aged <4 months, 4-9 months and >9 months, respectively. Explorative analyses showed EVI decreased during wheezing episodes from 14.4 (95% CI 13.2 to 15.7) to 9.6 (95% CI 5.6 to 13.5). Both EVI and tPTEF/tE tended to be lower in preterm than in term infants: EVI 14.6 (95% CI 13.5 to 15.8) versus 16.3 (95% CI 15.0 to 17.6) and tPTEF/tE 0.160 (95% CI 0.142 to 0.177) versus 0.187 (95% CI 0.158 to 0.216) CONCLUSIONS: Home IP measurement in preterm-born infants is moderately feasible, with improving success in older infants. Differences in EVI and tPTEF/tE by gestational maturity and during wheezing episodes indicate that IP provides clinically relevant information on airway obstruction, supporting its potential for research and future clinical use.