The feasibility of measuring airway derecruitment in paediatric patients with asthma

Abstract

Rationale: In adults with asthma, airway decruitment correlates with asthma control and is a strong predictor of uncontrolled asthma. Airway derecruitment is calculated from the relationship between respiratory system reactance (Xrs) and lung volume measured during a Vital Capacity (VC) manoeuvre. We aimed to determine whether measurement of airway derecruitment is feasible in paediatric patients with asthma. Method(s): 20 participants (13M/7F, age range: 9-20) with well-controlled, stable asthma performed forced oscillation technique (FOT) to measure Xrs at 5Hz and multiple breath nitrogen washout to measure FRC. FOT was performed twice; each measurement consisted of 30s of tidal breathing followed by two VC manoeuvres that were separated by tidal breathing. The onset of airway derecruitment (DR1) and the occurrence of rapid airway derecruitment (DR2) were defined as points of distinct gradient changes on the Xrs vs lung volume curve; the volume (as a percentage of TLC) and corresponding Xrs at these points were extracted. Within-session repeatability was expressed as SD and coefficient of variation (CV). Result(s): 20 participants performed a total of 78 VC manoeuvres, with 54 (69%) assessed as acceptable for analysis. 16 participants had at least two acceptable measurements. Flow tended to be less variable during acceptable measurements compared to unacceptable measurements (median [IQR]; 7.7 [2.0-2.1] vs 21.2 [7.2-41.0] mL/s, p=0.08), however there were no differences in mean flow or duration of VC (p=0.37 and 0.17 respectively). p class='Pa12' style='lineheight: normal'>Data presented as mean+/-SD. Conclusion(s): In paediatric patients with well-controlled asthma, airway derecruitment is a feasible measurement. Future research will be needed to determine its clinical utility in paediatric patients with asthma.