Background: There is a strong association between nutrition and long-term FEV1 in cystic fibrosis (CF), but studies have been driven by data from subjects with pancreatic insufficiency (PI-CF). We thus eval-uated the association between body mass index (BMI) and FEV1 percent-predicted (FEV1pp) in children with pancreatic sufficiency (PS-CF) and contrasted it with the association in PI-CF.Methods: We utilized data from the CF Foundation Patient Registry. The cohort included children born 1995-2010, diagnosed < 2 years of age, and who had annualized data on BMI percentile and FEV1pp at ages 6-16 years. Pancreatic status was defined based on pancreatic enzyme replacement therapy. The association between BMI and FEV1 was evaluated using linear and mixed-effects longitudinal regression.Results: There were 424 children with PS-CF and 7,849 with PI-CF. The association between BMI and FEV1 differed significantly by pancreatic status: each 10-pct higher BMI was associated with 2% [95%CI = 1.9- 2.1] higher FEV1pp in PI-CF, compared to just 0.9% [0.5-1.3] in PS-CF (PINTERACTION < 0.001). Within the at-risk nutritional category (BMI < 25pct), each 10-pct higher BMI was associated with 5% higher FEV1pp in PI-CF, but no significant increase in PS-CF. Moreover, in PS-CF, overweight/obesity (BMI > 85pct) was associated with decreasing FEV1pp. In addition, FEV1pp decline through age 20 years in youth with PS-CF was modest (-0.6% per year) and independent of BMI (BMI *age P-INTERACTION = 0.37).Conclusions: In children with PS-CF, BMI remains an important determinant of lung function. However, it may be less critical to attain a BMI > 50(th) percentile; and BMI > 85(th) percentile may be detrimental.(c) 2021 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

Introduction: Lung clearance index (LCI) is an important measure of lung function, especially in those with mild cystic fibrosis (CF). It is however challenging to deliver in infants, with current devices requiring 100% O2 washout or use of 4% SF6. We have previously described a novel portable method using 0.1% SF6 as the tracer gas. In this study we report longitudinal measurement of LCI using this method. Method: LCI measurements were undertaken using 0.1% SF6 and washout on air. All measurements were performed under light sedation, up to age 3.5 years. CF children, clinically stable at time of assessment, had LCI measured at initial visit, 2-4m later and 12-24m later. Healthy controls were measured once. The study took place in one US and two UK centres. Results: 32 CF infants had successful LCI at visit 1, six at visit 2 and five at visit 3 with data analysis still ongoing. Data are also available on 36 healthy infants. There was no difference in overall mean LCI in CF (mean 7.0, SD 0.7) vs controls (mean 7.0, SD 0.6), p=0.9. Median coefficient of variation of LCI repeats was 5.1%. Five of eight measurements in CF infants <52wks old and 15 of 35 measurements in infants >52wks of age showed LCI >7.0. Bland-Altman analysis of visits 1 vs 2 in six children showed a mean change of 0.25, and limits of agreement of -0.66 to 1.16 LCI units, similar to that described in older children. Conclusion: Infant LCI is feasible with light sedation and showed good short term repeatability. Although there was no overall difference in mean LCI, a large proportion of CF patients showed an elevated LCI in infancy.

The COVID pandemic has passed its first peak for now in many countries while some are still on the rise, with some facing a second wave of cases. Precautions and infection control measures for both pediatric and adult pulmonary function testing (PFT) have been a topic of debate during the pandemic. Many centers had to close their PFT laboratories during the initial periods of the pandemic and are reopening as the numbers of new cases are decreasing. This review aims to summarize different practices of PFT laboratory management in different countries, including patient appointments, personal protective equipment, testing room requirements and telemedicine during and immediately following the COVID pandemic.

Hintergrund Die Messung des Lung Clearance Index LCI mittels Multiple Breath Washout ist Goldstandard für Medikamentenstudien bei cystischer Fibrose CF. Das traditionelle Verfahren erfolgt durch Auswaschen des Lungen-Stickstoff mit Sauerstoff. Neue Methoden verwenden eine massenspektroskopische Messung von Schwefelhexafluorid SF6 als Tracergas. Vom LCI lassen sich Scond und Sacin ableiten. Scond ist dabei definiert als Steigung der Phase III der Auswaschkurven im Bereich Lung Turnover TO 1,5 – 6 (TO = Σ Tidalvolumina/FRC). Sacin ist die Steigung der Phase III der ersten Exhalatkurve. Scond misst die kleinen Atemwege, Sacin die azinären Strukturen.