Changes in exercise capacity in people with Cystic Fibrosis after one year of Elexacaftor/Tezacaftor/Ivacaftor treatment - A Danish prospective cohort.

BACKGROUND: Cystic Fibrosis (CF) is an inherited multiorgan disease that causes lung damage and early death. People with CF (pwCF) experience diminished exercise capacity compared to the general population. This is due to an accelerated decline in lung function resulting from recurrent lung infections, declining lung function and nutritional challenges. Since 2020 the CFTR-modulator Elexacaftor/Tezacaftor/Ivacaftor (ETI) has been approved for pwCF aged 12 and above in Denmark. Initial experiences with the medication have shown promising results, including improved lung function and disease stability. To date a limited number of studies have evaluated the impact of CFTR-modulators on exercise capacity in pwCF. OBJECTIVE: The study aims to assess the impact of one year of ETI treatment, without any further intervention, on exercise capacity measured through cardiopulmonary exercise test (CPET) in pwCF aged 12 years and above. METHODS: A Danish prospective registry cohort study including pwCF from CF-Center Copenhagen, Copenhagen University Hospital and CF-Center Aarhus, Aarhus University Hospital. Participants underwent CPET before initiating ETI and at follow up one year later. Primary outcomes were VO2 peak (ml/kg/min), secondary outcomes were VO2 peak (ml/min), VO2 peak (% pred), watt-max, HR-max and saturation at max. The difference between baseline and follow-up was assessed using a paired-sample t-test and regression analyses were applied to relevant outcomes. RESULTS: We included 229 pwCF in the analyses. An increase in oxygen uptake, VO2 peak (ml/kg/min) from baseline to follow-up was observed; 0.6, 95% CI [0.06; 1.09] p = 0.03. Moreover, significant increase was noted for all other CPET outcomes. Regression analysis showed that changes in FEV1% pred and BMI could explain some of the differences, 0.05 ml/kg/min, 95% CI [0.01, 0.1] p = 0.02 and -0.5 ml/kg/min, 95% CI [-0.8, -0.2] p = 0.002 respectively. CONCLUSION: Among Danish pwCF we found a significant, but not clinically relevant, increase in oxygen uptake, after one year of ETI treatment.

Close monitoring and early intervention: management principles for cystic fibrosis in Denmark.

Cystic fibrosis (CF) care in Denmark has been characterized by close monitoring and pre-emptive treatment of lung disease and other CF-related complications. Continuous evaluation through data collection and commitment to clinical research has incrementally improved outcomes. This approach has been in line with best practices set forth by European Standards of Care but has also gone beyond Society standards particularly pertaining to early treatment with high-dose combination antimicrobial therapy. Despite a high prevalence of severe CF variants, lung function has been among the best in Europe. In this review, the Danish approach to management of CF prior to the introduction of new CF modulator treatment is explained and benchmarked. Downsides to the Danish approach are discussed and include increased burden of treatment, risk of antimicrobial resistance, side-effects and costs.

Lung Function in Fontan Patients Over a Ten-Year Period: Is the Fontan Circulation Impairing Lung Development?

Few studies have investigated how the Fontan circulation affects lung function, and no studies have investigated the development of lung function over longer time in these patients. We aimed to describe the development of lung function in Fontan patients over a 10-year period. Pulmonary function tests (PFT), including spirometry and diffusion capacity for Carbon Monoxide (DLCO) and Nitric Oxide (DLNO), were conducted in a Danish Fontan cohort in 2011 (PFT-I). In 2021, re-investigations were performed (PFT-II). We investigated changes in percent predicted (%pred) lung function from PFT-I to PFT-II. Patients were categorized into a pediatric group (age under 18 at PFT-I) and an adult group (age 18 or older at PFT-I). Out of the 81 patients completing PFT-I, 48 completed PFT-II. In the pediatric group (32 patients), there were significant declines in %pred forced expiratory volume in 1s (99.7 (92.4, 104.4)-89.3 (84.9, 97.2), p < 0,001), forced vital capacity (98.3 (87.8, 106.1)-96.7 (86.7, 100.6), p = 0.008), and alveolar volume (95.5 (89.5, 101.6)-89.5 (79.7, 93.2), p < 0.001). The corresponding measurements remained stable in the adult group. However, the median %pred DLNO significantly declined in the adult group (58.4 (53.3, 63.5)-53.7 (44.1, 57.3), p = 0.005). Over a 10-year period, several lung function parameters declined significantly in the younger Fontan patients, suggesting possible impairments in lung development during growth. The decline in %pred DLNO in the adult patient group indicates deterioration of the membrane component of diffusion capacity, implying that the Fontan circulation might negatively affect the alveolar membrane over time.

Automatic analysis of bronchus-artery dimensions to diagnose and monitor airways disease in cystic fibrosis.

BACKGROUND: Cystic fibrosis (CF) lung disease is characterised by progressive airway wall thickening and widening. We aimed to validate an artificial intelligence-based algorithm to assess dimensions of all visible bronchus-artery (BA) pairs on chest CT scans from patients with CF. METHODS: The algorithm fully automatically segments the bronchial tree; identifies bronchial generations; matches bronchi with the adjacent arteries; measures for each BA-pair bronchial outer diameter (Bout), bronchial lumen diameter (Bin), bronchial wall thickness (Bwt) and adjacent artery diameter (A); and computes Bout/A, Bin/A and Bwt/A for each BA pair from the segmental bronchi to the last visible generation. Three datasets were used to validate the automatic BA analysis. First BA analysis was executed on 23 manually annotated CT scans (11 CF, 12 control subjects) to compare automatic with manual BA-analysis outcomes. Furthermore, the BA analysis was executed on two longitudinal datasets (Copenhagen 111 CTs, ataluren 347 CTs) to assess longitudinal BA changes and compare them with manual scoring results. RESULTS: The automatic and manual BA analysis showed no significant differences in quantifying bronchi. For the longitudinal datasets the automatic BA analysis detected 247 and 347 BA pairs/CT in the Copenhagen and ataluren dataset, respectively. A significant increase of 0.02 of Bout/A and Bin/A was detected for Copenhagen dataset over an interval of 2 years, and 0.03 of Bout/A and 0.02 of Bin/A for ataluren dataset over an interval of 48 weeks (all p<0.001). The progression of 0.01 of Bwt/A was detected only in the ataluren dataset (p<0.001). BA-analysis outcomes showed weak to strong correlations (correlation coefficient from 0.29 to 0.84) with manual scoring results for airway disease. CONCLUSION: The BA analysis can fully automatically analyse a large number of BA pairs on chest CTs to detect and monitor progression of bronchial wall thickening and bronchial widening in patients with CF.

Exercise capacity in the Danish Fontan population remains stable after ten years of follow-up - is physical activity the key to success?

BACKGROUND: Most Fontan patients have impaired exercise capacity, and a further decline in exercise capacity over time seems inevitable. However, few longitudinal studies exist, and there is a lack of data from newer eras. We aimed to describe the natural evolution of exercise capacity over a 10-year period in a contemporary, population-based cohort of Danish Fontan patients. METHODS: The study was a nationwide, prospective study. A cardiopulmonary exercise test (CPET) was used to assess the exercise capacity. All Danish Fontan patients who participated in a national study in 2011 (CPET1), were invited to a follow-up visit in 2021 (CPET2). All patients who completed CPET1 and CPET2 with a respiratory exchange ratio over 1.0 were included. The main outcome was percent predicted VO2peak (%pred VO2peak). At the time of CPET2, patients filled out a questionnaire including questions regarding physical activity. RESULTS: Seventy-seven patients completed both CPET1 and CPET2, and seventy patients completed the questionnaire. The time interval between the two CPETs was 10.4 ± 0.9 years. The median age was 15 years at CPET1 and 26 years at CPET2. The exercise capacity remained stable with a mean %pred VO2peak of 53.8 ± 11.3 at CPET1 and 55.6 ± 10.9 in CPET2 (p = 0.314). Higher levels of vigorous physical activity were associated with higher %pred VO2peak in CPET2 in a multivariate regression model. CONCLUSION: The %pred VO2peak remained stable over a ten-year period in this population-based Fontan cohort. Higher levels of self-reported vigorous physical activity were associated with higher %pred VO2peak in the most recent CPET.

Diffuse alveolar haemorrhage in children: an international multicentre study.

Background: Paediatric diffuse alveolar haemorrhage (DAH) is a rare heterogeneous condition with limited knowledge on clinical presentation, treatment and outcome. Methods: A retrospective, descriptive multicentre follow-up study initiated from the European network for translational research in children's and adult interstitial lung disease (Cost Action CA16125) and chILD-EU CRC (the European Research Collaboration for Children's Interstitial Lung Disease). Inclusion criteria were DAH of any cause diagnosed before the age of 18 years. Results: Data of 124 patients from 26 centres (15 counties) were submitted, of whom 117 patients fulfilled the inclusion criteria. Diagnoses were idiopathic pulmonary haemosiderosis (n=35), DAH associated with autoimmune features (n=20), systemic and collagen disorders (n=18), immuno-allergic conditions (n=10), other childhood interstitial lung diseases (chILD) (n=5), autoinflammatory diseases (n=3), DAH secondary to other conditions (n=21) and nonspecified DAH (n=5). Median (IQR) age at onset was 5 (2.0-12.9) years. Most frequent clinical presentations were anaemia (87%), haemoptysis (42%), dyspnoea (35%) and cough (32%). Respiratory symptoms were absent in 23%. The most frequent medical treatment was systemic corticosteroids (93%), hydroxychloroquine (35%) and azathioprine (27%). Overall mortality was 13%. Long-term data demonstrated persistent abnormal radiology and a limited improvement in lung function. Conclusions: Paediatric DAH is highly heterogeneous regarding underlying causes and clinical presentation. The high mortality rate and number of patients with ongoing treatment years after onset of disease underline that DAH is a severe and often chronic condition. This large international study paves the way for further prospective clinical trials that will in the long term allow evidence-based treatment and follow-up recommendations to be determined.

Withdrawal of dornase alfa increases ventilation inhomogeneity in children with cystic fibrosis.

BACKGROUND: The lung clearance index (LCI) is increasingly used as an outcome in clinical trials of patients with mild cystic fibrosis (CF) lung disease. Yet, understanding the impact of standard CF respiratory therapy on LCI is needed. We assessed to what degree withdrawal of nebulised dornase alfa affected LCI in school-age children with CF not receiving CFTR modulators or hydrator therapy. METHODS: A single-centre, randomised, controlled, parallel group study to determine effects of one month's withdrawal of nebulised dornase alfa (intervention) in 5-18 years old children with CF. Remaining chronic maintenance therapy stayed unchanged. Outcome measures were assessed at two visits one month apart. Primary outcome was absolute change in LCI. Secondary outcomes were FEV1, FEF25-75 and CF Questionnaire-revised (CFQ-R) respiratory symptom score. Possible harmful effects were assessed by comparing the occurrence of pulmonary exacerbations between groups. RESULTS: Twenty-eight children (median age 10.4 [interquartile range: 7.6; 13.5] years) with CF received standard care (n = 14) or intervention (n = 14). Compared with the control group, LCI increased (worsened) 1.74 (95% confidence interval: 0.62; 2.86) during withdrawal of dornase alfa, while FEV1 (-6.8% predicted) and FEF25-75 (-13.1% predicted) decreased significantly. Change in CFQ-R respiratory symptom score and the occurrence of pulmonary exacerbations did not differ significantly between groups. CONCLUSIONS: One month's withdrawal of dornase alfa caused increasing ventilation inhomogeneity and deteriorating FEV1 and FEF25-75 in school-age children with mild CF. Hence, adherence to dornase alfa optimally needs to be addressed when using LCI and spirometric parameters as endpoints, even in short-term clinical trials.

Prospective longitudinal association between repeated multiple breath washout measurements and computed tomography scores in children with cystic fibrosis.

BACKGROUND: Progression of structural lung disease (SLD) is a major risk factor for morbidity in patients with cystic fibrosis (CF). We studied changes in SLD and correlations with spirometry and nitrogen multiple breath washout (N2MBW) outcomes to explore associations in contemporary evolution between structural and functional abnormalities in CF lung disease. METHODS: Spirometry-controlled chest-CTs using PRAGMA-CF for scoring extent of SLD, spirometry, and N2MBW were performed at two-year intervals in school-age children with CF. RESULTS: Fifty-seven children aged 6-18 years were included. No significant progression in mean PRAGMA-CF scores was observed. Half of the children showed improvement in the proportion of bronchiectasis (%Bx). Lung Clearance Index (LCI) and the second moment ratio (M2) increased significantly and baseline values correlated significantly with SLD at follow-up (p ≤ 0.0002). The correlation between the change in M2 (∆M2) and the change in total SLD was R = 0.27 (p = 0.048). We found high negative predictive values (100%) for ∆M2<10% to exclude progression in SLD. For stable or improving values of LCI and M2, the predicted probability for progression in SLD was 16% and 14%, respectively (upper 95% confidence limit: 33%). Evolution in N2MBW and CT outcomes was discordant in half of the children. CONCLUSIONS: We found no progression in SLD over 2 years in school-age children with CF, in contrast to both LCI and M2, which along with discordant outcomes in half of the children underlines that N2MBW and CT assess different aspects of CF lung disease. However, stable outcomes from N2MBW were associated with stable structural lung disease.

Pulmonary function testing in children's interstitial lung disease.

The use of pulmonary function tests (PFTs) has been widely described in airway diseases like asthma and cystic fibrosis, but for children's interstitial lung disease (chILD), which encompasses a broad spectrum of pathologies, the usefulness of PFTs is still undetermined, despite widespread use in adult interstitial lung disease. A literature review was initiated by the COST/Enter chILD working group aiming to describe published studies, to identify gaps in knowledge and to propose future research goals in regard to spirometry, whole-body plethysmography, infant and pre-school PFTs, measurement of diffusing capacity, multiple breath washout and cardiopulmonary exercise tests in chILD. The search revealed a limited number of papers published in the past three decades, of which the majority were descriptive and did not report pulmonary function as the main outcome.PFTs may be useful in different stages of management of children with suspected or confirmed chILD, but the chILD spectrum is diverse and includes a heterogeneous patient group in all ages. Research studies in well-defined patient cohorts are needed to establish which PFT and outcomes are most relevant for diagnosis, evaluation of disease severity and course, and monitoring individual conditions both for improvement in clinical care and as end-points in future randomised controlled trials.

Lung clearance index-triggered intervention in children with cystic fibrosis - A randomised pilot study.

HYPOTHESIS: Using increase in the lung clearance index (LCI) as a trigger for bronchoalveolar lavage (BAL) and associated antimicrobial treatment might benefit clinical outcomes in children with cystic fibrosis (CF). METHODS: A 2-year, longitudinal, interventional, randomized, controlled pilot study with quarterly visits in 5-18 years old children with CF. LCI and z-scores for the forced expired volume in 1 s (zFEV1) and body mass index (zBMI) were obtained at every visit, CF Questionnaire-revised (CFQ-R) yearly and BAL and chest computed tomography at first and last visit. Children in the intervention group had BAL performed if LCI increased >1 unit from a fixed baseline value established at first visit. If the presence of a pathogen was documented in the BAL fluid, treatment was initiated/altered accordingly. RESULTS: Twenty-nine children with CF were randomized to the control (n = 14) and intervention group (n = 15). The median (interquartile range) number of BAL procedures per child was 2.5 (2.0; 3.0) and 6.0 (4.0; 7.0) in the control and intervention group, respectively. There was no significant difference between groups in slope for the primary outcome LCI; difference was 0.21 (95% confidence interval: -0.45; 0.88) units/year. Likewise, there was no significant difference between groups in slope for the secondary outcomes zFEV1, zBMI, CFQ-R respiratory symptom score and the proportion of total disease and trapped air on chest computed tomography. CONCLUSIONS: LCI-triggered BAL and associated antimicrobial treatment did not benefit clinical outcomes in a small cohort of closely monitored school-age children with CF.

Prevalence and course of disease after lung resection in primary ciliary dyskinesia: a cohort & nested case-control study.

BACKGROUND: Lung resection is a controversial and understudied therapeutic modality in Primary Ciliary Dyskinesia (PCD). We assessed the prevalence of lung resection in PCD across countries and compared disease course in lobectomised and non-lobectomised patients. METHODS: In the international iPCD cohort, we identified lobectomised and non-lobectomised age and sex-matched PCD patients and compared their characteristics, lung function and BMI cross-sectionally and longitudinally. RESULTS: Among 2896 patients in the iPCD cohort, 163 from 20 centers (15 countries) underwent lung resection (5.6%). Among adult patients, prevalence of lung resection was 8.9%, demonstrating wide variation among countries. Compared to the rest of the iPCD cohort, lobectomised patients were more often females, older at diagnosis, and more often had situs solitus. In about half of the cases (45.6%) lung resection was performed before presentation to specialized PCD centers for diagnostic work-up. Compared to controls (n = 197), lobectomised patients had lower FVC z-scores (- 2.41 vs - 1.35, p = 0.0001) and FEV1 z-scores (- 2.79 vs - 1.99, p = 0.003) at their first post-lung resection assessment. After surgery, lung function continued to decline at a faster rate in lobectomised patients compared to controls (FVC z-score slope: - 0.037/year Vs - 0.009/year, p = 0.047 and FEV1 z-score slope: - 0.052/year Vs - 0.033/year, p = 0.235), although difference did not reach statistical significance for FEV1. Within cases, females and patients with multiple lobe resections had lower lung function. CONCLUSIONS: Prevalence of lung resection in PCD varies widely between countries, is often performed before PCD diagnosis and overall is more frequent in patients with delayed diagnosis. After lung resection, compared to controls most lobectomised patients have poorer and continuing decline of lung function despite lung resection. Further studies benefiting from prospective data collection are needed to confirm these findings.

One-year evolution and variability in multiple-breath washout indices in children and young adults with primary ciliary dyskinesia.

Background and objective: Cross-sectional and longer-term studies have demonstrated abnormal yet stable multiple-breath inert gas washout (MBW) indices in patients with primary ciliary dyskinesia (PCD). This study aimed to assess the intermediate term evolution and the between-occasion variability of MBW indices in PCD over 1 year. Methods: Children and young adults with a confirmed diagnosis of PCD were included in this single-centre, prospective, observational, longitudinal study. Over 1 year, nitrogen (N2) MBW and spirometry were performed at three occasions during ordinary scheduled outpatient visits. Trends and variability in lung clearance index (LCI), moment ratios, normalized N2 concentration at six lung volume turnovers, and regional ventilation inhomogeneity indices of the conducting and intra-acinar airways (Scond*VT and Sacin*VT) were analysed using linear mixed models. Results: Forty-two patients, aged 6-29 years (median: 15.4), performed 116 N2 MBW test occasions and 96.6% were technically acceptable. A minimal, although significant, increase in LCI over 1 year (mean: 0.51 units, 95% CI: 0.12-0.91, p = 0.01) was found; while, all other N2 MBW indices and FEV1 remained unchanged. A moderate correlation was observed between LCI and FEV1 (r = -0.47, p = 0.0001). The limits of agreement between tests 1 year apart were for LCI: -1.96 to 2.98; Scond*VT: ± 0.039; Sacin*VT: -0.108 to 0.128. Conclusions: Children and young adults with PCD managed at a specialist centre showed slightly, but significant, increasing LCI and otherwise unchanged ventilation inhomogeneity indices and dynamic volumes over the intermediate term of 1 year. Estimates of the variability of N2 MBW indices may inform sample size calculations of future randomized controlled trials.

The impact of mannose-binding lectin polymorphisms on lung function in primary ciliary dyskinesia.

OBJECTIVE: Primary ciliary dyskinesia (PCD) is a congenital lung disease that leads to recurrent and chronic lung infection. The resulting inflammation causes lung damage and declines in lung function. Mannose-binding lectin (MBL) is a first line host defense protein of importance for the innate immunity. Polymorphisms in the MBL gene named MBL2 result in unstable and low functional levels MBL proteins. MBL insufficiency is linked to an increased risk of lung infection and to declines in lung function in patients with cystic fibrosis. We investigated whether there is a similar link in patients with PCD. METHODS: This retrospective longitudinal study included 85 patients with PCD. Diagnostics and age at diagnosis were recorded, complete spirometry data starting at diagnosis, and Pseudomonas aeruginosa infection status over the last 2 years were collected, and the patients were grouped according to MBL2 genotype status (MBL2-sufficient or MBL2-deficient). RESULTS: MBL-deficient patients were diagnosed almost 3 years earlier than MBL-sufficient patients (median 6.1 vs 8.9 years, P < 0.05). There were no differences in the first measured spirometry values, but MBL-deficient patients showed greater declines in forced expiratory volume in one sec (FEV1 ) than patients with MBL sufficiency (z-score: -0.049 per year [95% CI, -0.075; -0.021] vs -0.009 per year [95% CI, -0.033; 0.015]; P = 0.023). No differences were found in forced vital capacity (FVC), FEV1 /FVC, or infection status. CONCLUSION: MBL-deficiency, which is associated with MBL2 mutations, was associated with a lower age at diagnosis and with steeper declines in FEV1 in patients with PCD. This suggests that the MBL genotype might be a disease modifier in PCD.

Long-Term Lung Function and Exercise Capacity in Postinfectious chILD.

Background: Severe postinfectious diffuse pulmonary disease may clinically mimic other entities of children's interstitial lung disease and is clinically challenging comprising various disease severities despite treatment. Long-term lung function trend and physical capacity in children with postinfectious diffuse pulmonary disease are rarely reported. We investigated trends in pulmonary function by long-term follow-up and assessed physical capacity in such patients. Methods: We performed a descriptive, single-center follow-up study in children with biopsy-verified postinfectious diffuse pulmonary disease. Patients with completed primary treatment course were eligible for follow-up, including pulmonary function and exercise (VO2peak) testing. Results: Thirty patients with postinfectious diffuse pulmonary disease were identified and included. Median (range) age at diagnose was 27.5 (2-172) months after a mean lag time of 23 months. H. influenzae and rhinovirus were the most frequent pathogens. Fifteen patients were available for follow-up after mean (range) 7.6 (2-15) years of treatment completion. Lung clearance index (LCI2.5), forced expiratory volume in 1 second (FEV1), and bronchodilator responsiveness were abnormal in 80%, 53%, and 44%, respectively. Diffusion capacity for monoxide was abnormal in 7% and total lung capacity in 33%. Only 8% demonstrated low VO2peak, while 40% reported difficulties during physical exertion. Longitudinal data on spirometry (n = 14) remained unchanged from end of treatment throughout follow-up. A significant association was found between zLCI2.5 and zFEV1 (multiple linear regression; r 2 = 0.61; P = 0.0003). Conclusion: Postinfectious diffuse pulmonary disease in children carries a varying degree of chronic pulmonary impairment with onset of symptoms in the first months of life and a typical considerable lag time before diagnosis. Follow-up several years after the initial injury demonstrated moderate-to-severe peripheral airway impairment although no further lung function decline was found years after completion of treatment. Despite acceptable VO2peak, a considerable proportion struggled during heavy exercise.

Variation in treatment strategies for the eradication of Pseudomonas aeruginosa in primary ciliary dyskinesia across European centers.

Primary ciliary dyskinesia (PCD) is a rare disease causing motile cilia dysfunction, recurrent airway infection, and bronchiectasis. Airway infection management strategies are borrowed from cystic fibrosis. The aim of this study is to describe the management of airway infection with Pseudomonas aeruginosa ( PA) in children and adults with PCD across European centers. An online survey questionnaire was sent electronically using SurveyMonkey® to 55 PCD centers in 36 European countries. Fifty-two responded from 43 centers in 26 countries, a response rate of 70%. Most (89%) countries did not have written guidelines for PCD management. Airway sampling for infection detection at each clinic visit was more likely when follow-up was frequent. Eighty-seven percent of centers chose to treat the first PA isolate, most prescribing combined oral ciprofloxacin and inhaled colistimethate sodium (43%, n = 18). The preferred treatment for chronic infection with PA was nebulized colistimethate in 51% ( n = 22). In summary, considerable variation exists across European centers in the frequency of patient follow-up and airway sampling for infection, treatment goals, and the management of PA infection. Few centers had written guidelines for PCD management. Clinical trials to determine optimal treatment of PA in PCD patients are urgently needed.

Ventilation inhomogeneity and NO and CO diffusing capacity in ex-premature school children.

AIM: Ex-premature school children show mild-to-moderate airway obstruction and decreased CO diffusing capacity. Multiple breath nitrogen washout (N2MBW) and NO diffusing capacity (DLNO) measurements may provide new insight into long-term pulmonary and vascular impairment in bronchopulmonary dysplasia (BPD). METHODS: We examined a randomly selected group of 70 ex-premature children (gestational age <28 weeks or birth weight <1500 g; 42 with and 28 without BPD) and 38 term-born healthy controls of 8-13 years of age. Subjects performed N2MBW (lung clearance index, LCI; Sacin, and Scond), DLNO (membrane related diffusing capacity, Dm and pulmonary capillary volume, Vc), Fractional exhaled NO, CO diffusing capacity, conventional spirometry (FEV1, FVC, FEF25-75) and plethysmography (RV, TLC). Respiratory symptoms were assessed by questionnaire. RESULTS: Compared to healthy controls, the BPD group had higher z-scores for lung clearance index (P = 0.003), Sacin (P = 0.005), lower CO diffusing capacity (P = 0.025), DLNO (P = 0.022), DLNO/VA z-scores (P = 0.025) and a significant larger proportion had respiratory complaints. Amongst ex-premature children, the BPD group did not differ from the non-BPD group except for a decreased Dm (P = 0.023). Ex-premature with BPD showed predominantly airway obstruction (FEV1/FVC; P < 0.0001), signs of hyperinflation (RV/TLC-ratio; P = 0.028), and 25% had a positive bronchodilator response (>12% in FEV1). CONCLUSION: Ex-premature school children exhibited relatively mild but significant long-term respiratory symptoms and pulmonary peripheral impairment judged by N2MBW and DLNO measurements along with well-known airway obstruction. Larger longitudinal studies are needed to assess the clinical use of these advanced methods of assessing ventilation inhomogeneity and DLNO.

Variability of monthly nitrogen multiple-breath washout during one year in children with cystic fibrosis.

BACKGROUND: Knowledge of between-session variability of nitrogen multiple-breath washout (N2MBW) indices is crucial when designing longitudinal interventional studies and in disease monitoring using N2MBW as end-point. Such information is currently sparse. METHODS: Monthly triplets of N2MBW were prospectively obtained from 14 children with CF during one year. Linear mixed models were used to analyze variability. Our aim was to assess between-session variability of N2MBW indices from repeated measurements and compare LCI derived from different software packages currently in use (TestPoint® vs. Spiroware®). RESULTS: Baseline LCI (median; range) was 9.37 (6.82; 12.08). Between-session differences in LCI measurements were up to 25%. Intra Class Correlation-Coefficient was 0.82. There was no systematic difference between LCI measurements derived from the two software packages (p=0.18); however, variability was significantly higher using Spiroware®. CONCLUSIONS: We report between-session variability of LCI using N2MBW in school-age children and adolescents with CF. LCI changes exceeding 25% may be considered clinically relevant. TestPoint® and Spiroware® can be used interchangeably in longitudinal studies.

Fractional exhaled nitric oxide and multiple breath nitrogen washout in preschool healthy and asthmatic children.

INTRODUCTION: Objectively assessing pulmonary disease is challenging in preschool children with asthma. We evaluated the feasibility of measuring fractional exhaled nitrogen oxide (FeNO) and multiple breath nitrogen washout (N2MBW) in children. We compared their capacities for discriminating between children with asthma and healthy controls. METHODS: We measured FeNO and N2MBW-derived indices of lung clearance (LCI2.5) and conductive and acinar ventilation heterogeneity (Scond and Sacin) in 65 preschool children; 35 with physician-diagnosed asthma and 30 healthy. FeNO was measured with a portable device (sampling time, 6 s). We employed data quality control guidelines on N2MBW. Feasibility was evaluated in a maximum of 8 attempts for both methods. Atopic co-morbidity and first-degree disposition were evaluated with the ISAAC-questionnaire. RESULTS: FeNO and N2MBW testing were feasible in 45% and 91% of children, respectively. Feasibility was highly age-dependent. In children under 4 years old, FeNO was not feasible, but N2MBW was 85% feasible. Children with asthma had significantly elevated Scond values (median; 95% CI) (0.024; 0.020; 0.029) compared to healthy controls (0.019; 0.016; 0.023), but similar FeNO, LCI2.5 and Sacinvalues. CONCLUSION: The feasibility of measuring FeNO was highly age-dependent and not applicable in children under age 4. N2MBW was feasible in the majority of preschool children. Scond, but not FeNO, could discriminate between children with asthma and healthy controls.