A Short extension to multiple breath washout provides additional signal of distal airway disease in people with CF: A pilot study

• Published in: Journal of cystic fibrosis Vol. 21; no. 1; pp. 146 - 154
• Main Authors: Short, Christopher, Semple, Thomas, Saunders, Clare, Hughes, Dominic, Irving, Samantha, Gardener, Laura, Rosenthal, Mark, Robinson, Paul D., Davies, Jane C.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.01.2022
• Subjects: Adolescent; Adult; Air Trapping; Biomarkers; Breath Tests - methods; Child; Child, Preschool; Computed Tomography (CT); Cystic fibrosis (cf); Cystic Fibrosis - diagnostic imaging; Cystic Fibrosis - physiopathology; Female; Humans; Lung Clearance Index (LCI); Lung Function Testing; Male; Multiple breath washout (mbw); Pilot Projects; Pulmonary function testing (pft); Pulmonary physiology; Pulmonary/Respiratory; Respiratory Function Tests - methods; Tomography, X-Ray Computed; Young Adult; Lung Clearance Index (LCI); Lung Function Testing; Pulmonary function testing (pft); Computed Tomography (CT); Pulmonary physiology; Biomarkers; Cystic fibrosis (cf); Air Trapping; Multiple breath washout (mbw)
• ISSN: 1569-1993; 1873-5010; 1873-5010
• DOI: 10.1016/j.jcf.2021.06.013

•MBW with short extension (MBWShX) is feasible with children from 5 years of age.•LCIShX is repeatable during clinical stability and has a larger signal around episodes of PEx.•The extent of under/ unventilated lung units cannot be predicted by the baseline LCI2.5.•Further studies will build on this pilot data to fully establish its utility in monitoring disease status. Adding a slow vital capacity (SVC) to multiple breath washout (MBW) allows quantification of otherwise overlooked signal from under/un-ventilated lung units (UVLU) and may provide a more comprehensive assessment of airway disease than conventional lung clearance index (LCI2.5). We conducted a pilot study on people undergoing MBW tests: 10 healthy controls (HC) and 43 cystic fibrosis (CF) subjects performed an SVC after the standard end of test. We term the new outcome LCI with Short extension (LCIShX). We assessed (i) CF/ HC differences, (ii) variability (iii) effect of pulmonary exacerbation (PEx)/treatment and (iv) relationship with CF computed tomography (CFCT) scores. HC/ CF group differences were larger with LCIShX than LCI2.5 (P<0.001). Within the CF group UVLU was highly variable and when abnormal it did not correlate with corresponding LCI2.5. Signal showed little variability during clinical stability (n = 11 CF; 2 visits; median inter-test variability 2.6% LCIShX, 2.5% LCI2.5). PEx signal was significantly greater for LCIShX both for onset and resolution. Both MBW parameters correlated significantly with total lung CT scores and hyperinflation but only LCIShX correlated with mucus plugging. UVLU captured within the LCIShX varies between individuals; the lack of relationship with LCI2.5 demonstrates that new, additional information is being captured. LCIShX repeatability during clinical stability combined with its larger signal around episodes of PEx may lend it superior sensitivity as an outcome measure. Further studies will build on this pilot data to fully establish its utility in monitoring disease status.