Respiratory impedance in children with cystic fibrosis using forced oscillations in clinic

Measurement of lung function is an important component of clinical management in cystic fibrosis (CF), but has been difficult in young children. The present study aimed to characterise the utility of the forced oscillation technique for measurement of lung function in preschool-aged children with CF in a routine clinical setting. Lung function was assessed in 56 young children (aged 2-7 yrs) with CF. Respiratory system resistance (Rrs) and reactance (Xrs) at 6, 8 and 10 Hz were measured and expressed as Z-scores. Children were classified as asymptomatic or symptomatic based on an administered respiratory questionnaire and physical examination at the time of testing. Between-test repeatability was assessed in 25 children. Measurement of lung function using the forced oscillation technique was feasible in the CF clinic. The children with CF, as a group, had Z-scores for Rrs at 6 Hz (Rrs,6) Rrs,8, Rrs,10, Xrs at 6 Hz (Xrs,6) and Xrs,8 that were significantly different from zero. Children with current symptoms showed significantly decreased Xrs and increased Rrs,6 compared with asymptomatic children. Measurement of lung function using the forced oscillation technique is feasible in young children with cystic fibrosis in a clinical setting. The technique has the potential to improve knowledge concerning early cystic fibrosis lung disease.