Sensitive measures of lung function applicable to young subjects are needed to detect early cystic fibrosis (CF) lung disease. Forty children with CF aged 2 to 5 years and 37 age-matched healthy control subjects performed multiple-breath inert gas washout, plethysmography, and spirometry. Thirty children in each group successfully completed all measures, with success on first visit being between 68 and 86% for all three measures. Children with CF had significantly higher lung clearance index (mean [95% CI] difference for CF control 2.7 [1.9, 3.6], p < 0.001) and specific airway resistance (1.65 z-scores [0.96, 2.33], p < 0.001), and significantly lower forced expired volume in 0.5 seconds (-0.49 z-scores [-0.95, -0.03], p < 0.05). Abnormal lung function results were identified in 22 (73%) of 30 children with CF by multiple-breath washout, compared with 14 (47%) of 30 by plethysmography, and 4 (13%) of 30 by spirometry. Children with CF who were infected with Pseudomonas aeruginosa had significantly higher lung clearance index, but no significant difference in other lung function measures, when compared with noninfected children. Most preschool children can perform multiple-breath washout, plethysmography, and spirometry at first attempt. Multiple-breath washout detects abnormal lung function in children with CF more readily than plethysmography or spirometry.

Background: Lung clearance index (LCI), a measure of ventilation inhomogeneity derived from the multiplebreath inert gas washout (MBW) technique, has been shown to detect abnormal lung function more readily than spirometry in preschool children with cystic fibrosis, but whether this holds true during infancy is unknown. Objectives: To compare the extent to which parameters derived from the MBW and the raised lung volume rapid thoraco-abdominal compression (RVRTC) techniques identify diminished airway function in infants with cystic fibrosis when compared with healthy controls. Methods: Measurements were performed during quiet sleep, with the tidal breathing MBW technique being performed before the forced expiratory manoeuvres. Results: Measurements were obtained in 39 infants with cystic fibrosis (mean (SD) age 41.4 (22.0) weeks) and 21 controls (37.0 (15.1) weeks). Infants with cystic fibrosis had a significantly higher respiratory rate (38 (10) vs 32 (5) bpm) and LCI (8.4 (1.5) vs 7.2 (0.3)), and significantly lower values for all forced expiratory flow-volume parameters compared with controls. Girls with cystic fibrosis had significantly lower forced expiratory volume ) than boys (mean (95% CI girls-boys): -1.2 (-2.1 to 20.3) for FEV 0.5 Z score; FEF 25-75 : -1.2 (-2.2 to 20.15)). When using both the MBW and RVRTC techniques, abnormalities were detected in 72% of the infants with cystic fibrosis, with abnormalities detected in 41% using both techniques and a further 15% by each of the two tests performed. Conclusions: These findings support the view that inflammatory and/or structural changes in the airways of children with cystic fibrosis start early in life, and have important implications regarding early detection and interventions. Monitoring of early lung disease and functional status in infants and young children with cystic fibrosis may be enhanced by using both MBW and the RVRTC.

This study demonstrates that an abnormal preschool LCI predicts subsequent lung function abnormalities, whereas a normal preschool LCI usually remains normal. MBW has potential as a clinical and research outcome in young children with CF.

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.

Background Long-term benefits of newborn screening (NBS) for cystic fibrosis (CF) have been established with respect to nutritional status, but effects on pulmonary health remain unclear. Hypothesis With early diagnosis and commencement of standardised treatment, lung function at w3 months of age is normal in NBS infants with CF. Methods Lung clearance index (LCI) and functional residual capacity (FRC) using multiple breath washout (MBW), plethysmographic (pleth) FRC and forced expirations from raised lung volumes were measured in 71 infants with CF (participants in the London CF Collaboration) and 54 contemporaneous healthy controls age w3 months. Results Compared with controls, and after adjustment for body size and age, LCI, FRC MBW and FRC pleth were significantly higher in infants with CF (mean difference (95% CI): 0.5 (0.1 to 0.9), p¼0.02; 0.4 (0.1 to 0.7), p¼0.02 and 0.9 (0.4 to 1.3), p<0.001, z-scores, respectively), while forced expiratory volume (FEV 0.5 ) and flows (FEF 25e75 ) were significantly lower (À0.9 (À1.3 to À0.6), p<0.001 and À0.7 (À1.1 to À0.2), p¼0.004, z-scores, respectively). 21% (15/70) of infants with CF had an elevated LCI (>1.96 z-scores) and 25% (17/68) an abnormally low FEV 0.5 (below À1.96 z-scores). While only eight infants with CF had abnormalities of LCI and FEV 0.5 , using both techniques identified abnormalities in 35% (24/68). Hyperinflation (FRC pleth >1.96 z-scores) was identified in 18% (10/56) of infants with CF and was significantly correlated with diminished FEF 25e75 (r¼À0.43, p<0.001) but not with LCI or FEV 0.5 . Conclusion Despite early diagnosis of CF by NBS and protocol-driven treatment in specialist centres, abnormal lung function, with increased ventilation inhomogeneity and hyperinflation and diminished airway function, is evident in many infants with CF diagnosed through NBS by 3 months of age.

This study aimed to investigate the evolution of airway function in infants newly diagnosed with cystic fibrosis (CF). FEV(0.5) was measured soon after diagnosis (median age of 28 weeks) and 6 months later in subjects with CF and on two occasions 6 months apart (median ages of 7.4 and 33.7 weeks) in healthy infants, using the raised-volume technique. Repeated measurements were successful in 34 CF and 32 healthy subjects. After adjustment for age, length, sex, and exposure to maternal smoking, mean FEV(0.5) was significantly lower in infants with CF both shortly after diagnosis and at the second test, with no significant difference in rate of increase in FEV(0.5) with growth between the two groups. When compared with published reference data, FEV(0.5) was reduced by an average of two z scores on both test occasions in those with CF, with 72% of individuals having an FEV(0.5) of less than 1.64 z-scores (i.e., less than the fifth percentile) on one or both test occasions. On longitudinal analysis, subjects with CF experienced a mean (95% confidence interval) reduction in FEV(0.5) of 20% (11, 28). Airway function is diminished soon after diagnosis in infants with CF and does not catch up during infancy and early childhood. These findings have important implications for early interventions in CF.

This is the first study to describe physiologic measurements from infancy through the preschool years in subjects with CF and healthy control subjects, the understanding of which is critical for future intervention trials. Airflow obstruction in uncomplicated CF persists through the preschool years despite treatment, with PsA acquisition being associated with further deterioration in lung function, even when apparently eradicated. This suggests that new therapies are needed to treat the airflow obstruction of uncomplicated CF, and rigorous strategies to prevent PsA acquisition.

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