Lung compartment analysis assessed from N2 multiple-breath washout in children with cystic fibrosis.

BACKGROUND: Compartment analysis (CA) based on nitrogen multiple-breath washout (N2 MBW) has been shown to allow the assessment of specific volume and ventilation of faster- and slower-ventilating lung compartments of the lung in adults with cystic fibrosis (CF). The aim of this study was to extend previous findings into the pediatric age range. METHODS: Cross-sectional multicenter observational study in children with CF and healthy controls (HC) was done with the assessment of N2 MBW and spirometry. A two-lung compartment model-based analysis (CA) was used to estimate size and function of faster- and slower-ventilating lung compartments from N2 MBW. RESULTS: A total of 125 children with CF and 177 HC, median age 10.8 (range, 2.8-18.9) years, were included in the analysis. CA could be calculated in 66 (53%) children with CF compared with 48 (27%) HC (P < .0001). The proportion of the slower-ventilating lung compartment was significantly smaller in children with CF (53.5%; 95% confidence interval [CI]: 51.9%-55.7%) compared with HC (62.2%; 95% CI: 59.0%-65.0%) The regional specific ventilation of the slower compartment (rVT ,slow/rFRC,slow, %) was significantly lower in children with CF (4.9%; 95% CI: 4.5-5.9) compared with HC (9.7%, 95% CI: 9.2-10.9), and showed inverse correlation to lung clearance index (r2 = -.65; P < .0001), Sacin × VT (r2 = -.36; P = .003) and Scond × VT (r2 = -.51; P < .0001). There was no significant difference in pulmonary parameters between children with CF with and without feasible CA. CONCLUSION: CA is less feasible in children than in adults and correlated to other MBW parameters. The clinical value of CA is still unclear and is yet to be established.

Lung clearance index for early detection of pulmonary complications after allo-HSCT in children.

BACKGROUND: Pulmonary chronic graft-vs-host disease (cGvHD) after hematopoietic stem cell transplantation (HSCT) is characterized by impairment of the small airways. Assessment of lung clearance index (LCI) gained from multiple breath washout (MBW) is more sensitive than spirometry in detection of small airways disease. The aim of this study was to describe the development of LCI during the first year after pediatric HSCT and how LCI relates to other pulmonary function parameters and cGvHD. METHODS: This prospective, longitudinal study included 28 pediatric HSCT-recipients. Spirometry, Sulfur hexafluoride MBW and diffusion capacity of the lungs were performed before and at 3, 6, 9, and 12 months after HSCT. Respiratory symptoms and signs of cGvHD were recorded at each visit. RESULTS: Before HSCT, 47.8% had abnormal LCI and 12.5% had abnormal forced expiratory volume in 1 second (FEV1 ). Patients with persisting respiratory symptoms 12 months post-HSCT had higher median LCI (factor 5.7, P = 0.0018) and lower FEV1 z-scores (-1.5, P = 0.033) post-HSCT compared to patients free of respiratory symptoms. Overall, post-HSCT LCI values were 3.49 times higher and FEV1 was 2.31 z-scores lower in eight patients with cGvHD in any organ system compared with patients without cGvHD (P = 0.0089 and P < 0.0001). LCI values during the first 3 months were not predictive of pulmonary cGvHD. CONCLUSION: LCI is a sensitive marker for cGvHD and high LCI values were associated with persisting respiratory symptoms after 1 year. Further evaluation of MBW in early detection of HSCT-related pulmonary complications require larger patient cohorts and closer follow-up during the first months after HSCT.