Lung Clearance Index and HRCT are complementary markers of lung abnormalities in young children with CF

Abstract

Rationale High resolution computed tomography (HRCT) is a more sensitive tool for detecting early cystic fibrosis (CF) lung disease than either spirometry or plain radiography, but its relationship to other measures of lung function has not been established in young children. Objectives 1) To assess whether the lung clearance index (LCI) derived from multiple breath inert-gas washout (MBW) is as effective as HRCT in identifying pulmonary abnormalities; and 2) explore the relationships between abnormalities detected by HRCT and by spirometry, plethysmography and MBW (collectively, LFTs) in young children with CF. Methods Children with CF underwent LFTs and volumetric HRCT on the same day. Healthy age-matched controls underwent identical LFTs without HRCT. Scans were anonymised, and scored using the Brody-II CT scoring system, to assess for presence and extent of bronchiectasis, airway wall thickening, mucus plugging, and parenchymal opacities. Results Assessments were undertaken in 60 children with CF (mean (SD) 7.8 (1.3) years) and 54 healthy controls (7.9 (1.2) y). Among children with CF, 84% (47/ 56) had abnormal LCI, 58% (27/47) abnormal plethysmographic lung volumes (FRC pleth or RV), 35% (21/60) abnormal sRaw and 47% (28/60) abnormal spirometry (FEV 1 or FEF 25e75 ); whereas HRCT scans were abnormal in 85% (51/60): median total Brody-II score: 9.5% (range 0e51%). Total CT score correlated more strongly with LCI (Spearman correlation¼0.77) than with spirometry (R¼À0.43) or any other marker of lung function. Of the nine children with normal LCI, five had abnormalities on HRCT, whereas five children with normal HRCT had raised LCI. Conclusions These results suggest that while LCI and HRCT have similar sensitivity to detect CF lung disease, complimentary information may be gained in individual patients.

Impact of lung disease on respiratory impedance in young children with cystic fibrosis

“…As a tidal breathing test, MBW is easier to perform than spirometry [15]. The lung clearance index (LCI) from the MBW test is the first index to decline in preschool children with CF and is more sensitive than forced expiratory volume in 1 s to detect underlying lung disease [15,16,39]. Further research is needed to evaluate the ability of the LCI to detect lower respiratory tract inflammation, infection or structural disease in children with CF aged 3-6 years.…”

Is Lung Clearance Index (LCI) Affected by the Severity of Lung Disease in CF?

“…During last decades, an increased interest for MBW method among patients suffering from CF has been noted [3,4,[33][34][58][59][60][61][62][63] MBW is a non-invasive method, feasible to be performed and without the risk of radiation exposure [64]. A lot of studies have suggested that LCI has the advantage over FEV 1 to detect CF lung disease in earlier stages [21,36,38,[64][65][66][67][68].…”

“…Computed Tomography scores have shown a good correlation with Lung Clearance Index (LCI) [5,[32][33][34], a marker being measured by the Multiple Breath Washout method (MBW). MBW is a non-invasive and safe test for assessing ventilation inhomogeneity.…”

Chest Computed Tomography Predicts the Frequency of Pulmonary Exacerbations in Children with Cystic Fibrosis

“…Thus, patients with near-normal chest CT scores, who are unlikely to have more than a few pulmonary exacerbations, may do well without one or more of these therapies. Newer modalities such as the Lung Clearance Index and magnetic resonance imaging may provide similar diagnostic and prognostic information as chest CT scores (36,37), without exposure to excessive ionizing radiation. However, neither of these modalities is available for clinical care or been established as surrogate end points for clinical trials.…”