Single-breath washout and association with structural lung disease in children with cystic fibrosis

Abstract

Background: In children with cystic fibrosis (CF) lung clearance index (LCI) from multiple-breath washout (MBW) correlates with structural lung disease. As a shorter test, single-breath washout (SBW) represents an attractive alternative to assess theventilation distribution, however, data for the correlation with lung imaging are lacking.

Methods: We assessed correlations between phase III slope (SIII) of double-tracer gasSBW, nitrogen MBW indices (LCI and moment ratios for overall ventilation distribution,Scond, and Sacin for conductive and mainly acinar ventilation, respectively) andstructural lung disease assessed by chest computed tomography (CT) in children with CF.

Results: In a prospective cross-sectional study data from MBW, SBW, and chest CTwere obtained in 32 children with CF with a median (range) age of 8.2 (5.2-16.3) years.Bronchiectasis was present in 24 (75%) children and air trapping was present in 29(91%). Median (IQR) SIII of SBW was −138.4 (150.6) mg/mol. We found no associationbetween SIII with either the MBW outcomes or CT scores (n = 23, association with bronchiectasis extent r = 0.10, P = 0.64). LCI and Scond were associated with bronchiectasis extent (n = 23, r = 0.57, P = 0.004; r = 0.60, P = 0.003, respectively).

Conclusions: Acinar ventilation in homogeneity measured by SBW was not associated with structural lung disease on CT. Double-tracer SBW added no benefit to indices measured by MBW.

Authors: Sophie Yammine, Kathryn A. Ramsey, Billy Skoric, Louise King, Philipp Latzin, Tim Rosenow, Graham L. Hall, Sarath C. Ranganathan, AREST CF.

Published in Pediatratric Pulmonology in January 2019.