Abbreviation modalities of nitrogen multiple-breath washout tests in school children with obstructed lung disease

RATIONALE

Nitrogen multiple-breath washout (N2 MBW) is a promising tool for assessing early lung damage in children with chronic obstructive pulmonary disease, but it can be a time-consuming procedure. We compared alternative test-shortening endpoints with the most commonly reported N2 MBW outcome, the lung clearance index, calculated as lung volume turnovers required to reach 2.5% of the starting N2 concentration (LCI2.5 ).

METHODS

Cross-sectional study of triplicate N2 MBW measurements obtained in cystic fibrosis (CF) patients (N = 60), primary ciliary dyskinesia (PCD) patients (N = 28), and matched healthy controls (N = 48) aged 5-18 years. Bland-Altman analysis was used to compare LCI2.5 with earlier LCI endpoints (3%, 4%, 5%, 7%, and 9% of starting N2 concentration), Cn@TO6 (defined as % of N2 starting concentration when reaching six lung volume turnovers), and LCI derived from only two N2 MBW runs in each session. N2 MBW endpoints were analyzed as z-scores calculated from healthy controls.

RESULTS

In PCD, Cn@TO6 and LCI2.5 exhibited similar values (mean [95%CI] difference: 0.33 [-0.24; 0.90] z-scores), reducing the test duration by one-third (5.4 min; 95%CI: 4.0; 6.8). All other tested alternative endpoints exhibited increasing disagreement with increasing LCI2.5 . With an average reduction in test duration of 40%, LCI2.5 derived from two runs exhibited good agreement in all children.

CONCLUSIONS

Cn@TO6 may be suggested as a potential test-shortening endpoint in school children with PCD. In CF, early test termination may reduce measurement power with advancing pulmonary disease, suggesting differences in underlying pathophysiology. Two technically acceptable N2 MBW runs may be sufficient in school children irrespective of diagnosis with CF or PCD. Pediatr Pulmonol. 2016;51:624-632. © 2015 Wiley Periodicals, Inc.

Proceedings of the 4th BEAT-PCD Conference and 5th PCD Training School

Primary ciliary dyskinesia (PCD) is an inherited ciliopathy leading to chronic suppurative lung disease, chronic rhinosinusitis, middle ear disease, sub-fertility and situs abnormalities. As PCD is rare, it is important that scientists and clinicians foster international collaborations to share expertise in order to provide the best possible diagnostic and management strategies. 'Better Experimental Approaches to Treat Primary Ciliary Dyskinesia' (BEAT-PCD) is a multidisciplinary network funded by EU COST Action (BM1407) to coordinate innovative basic science and clinical research from across the world to drive advances in the field. The fourth and final BEAT-PCD Conference and fifth PCD Training School were held jointly in March 2019 in Poznan, Poland. The varied program of plenaries, workshops, break-out sessions, oral and poster presentations were aimed to enhance the knowledge and skills of delegates, whilst also providing a collaborative platform to exchange ideas. In this final BEAT-PCD conference we were able to build upon programmes developed throughout the lifetime of the COST Action. These proceedings report on the conference, highlighting some of the successes of the BEAT-PCD programme.

Associations between respiratory pathogens and lung function in primary ciliary dyskinesia: cross-sectional analysis from the PROVALF-PCD cohort

Introduction

Respiratory pathogens are frequently isolated from airway samples in primary ciliary dyskinesia (PCD) patients. Few studies have investigated associations between these pathogens and lung function, with current management based on evidence from cystic fibrosis. We investigated the association between commonly isolated respiratory pathogens and lung function in PCD patients.

Methods

Using a cross-sectional design, we prospectively collected clinical and concurrent microbiology data from 408 participants with probable or confirmed PCD, aged ≥5 years, from 12 countries. We used Global Lung Function Initiative 2012 references to calculate forced expiratory volume in 1 s (FEV1) z-scores. For 351 patients (86%) with complete data, we assessed the association of the four most frequently isolated pathogens with lung function by fitting multilevel linear models with country as random intercept, adjusted for age at diagnosis, age at lung function, use of antibiotic prophylaxis and body mass index z-scores.

Results

Individuals with Pseudomonas aeruginosa growth in culture had significantly lower FEV1 z-scores (β= -0.87, 95% CI -1.40- -0.34), adjusted for presence of Haemophilus influenzae, methicillin-sensitive Staphylococcus aureus and Streptococcus pneumoniae, and for covariates. When stratified by age, associations remained strong for adults but not for children. Results were similar when ciliary defects by transmission electron microscopy were included in the models and when restricting analysis to only confirmed PCD cases.

Conclusions

We found that P. aeruginosa was associated with worse lung function in individuals with PCD, particularly adults. These findings suggest that it is prudent to aim for P. aeruginosa eradication in the first instance, and to treat exacerbations promptly in colonised patients.