Assessing small airways dysfunction in asthma, asthma remission and healthy controls using particles in exhaled air

Abstract

Asthma is a chronic disease, characterised by variable airflow obstruction and airway inflammation [1]. Small airways are thought to be a major site of pathology in asthma [2, 3]. There are different tools to assess small airways dysfunction (SAD), such as spirometry, body plethysmography, impulse oscillometry (IOS), multiple-breath nitrogen washout (MBNW), alveolar fraction of exhaled nitric oxide (FENO) and gas trapping assessed by high-resolution computed tomography (CT). However, there is no golden standard and some tests are difficult to perform [2, 3].

Comparison of particles in exhaled air and multiple breath washout for assessment of small airway function in children with cystic fibrosis

“…In the studies with adults, the median outcomes of PExA in COPD and asthma were even higher than the outcomes in our healthy volunteers. [17][18][19] The low particle mass may be explained by the young age of our participants or difficulties in implementing the breathing maneuver.…”

“…Therefore we used the data of Carpaij et al In this study, they compared PExA outcomes between healthy adults and adults with asthma. 19 To achieve a power of 90% with a two-sided significance level (α) of 0.05, 11 participants need to be included per group. With a dropout rate of 25% we aimed for an enrollment of 15 children per group.…”

“…It has been shown that PExNR is significantly lower in adults with asthma and COPD than healthy controls and that intra-individual day to day and long term (3 months) variability in PExA outcomes is very low. 10,[16][17][18][19][20][21][22] In children, no data are published yet. One abstract reported that children with asthma have lower PExA counts than healthy controls 22 Thus, to the best of our knowledge, no published evidence for PExA is available in childhood and CF patients, and its comparison with MBNW, as a proven sensitive marker to detect SAD, is not known.…”

“…Based on the results of studies in adults with asthma and COPD, we hypothesized that in more severe SAD less particles are formed and exhaled due to impaired reopening of airways, altered composition of the respiratory lining fluid, or increased deposition of produced particles. [17][18][19] The primary aim of this study was to investigate differences in PExA outcomes in healthy children, and children with CF with normal lung function (CF-N), and CF with airway obstruction (CF-AO).…”

“…The first reports on PExA showed promising results in adult patients with obstructive airways disease. It has been shown that PExNR is significantly lower in adults with asthma and COPD than healthy controls and that intra‐individual day to day and long term (3 months) variability in PExA outcomes is very low 10,16–22 . In children, no data are published yet.…”