Improved childhood asthma control after exposure reduction interventions for desert dust and anthropogenic air pollution: the MEDEA randomised controlled trial

INTRODUCTION

Elevated particulate matter (PM) concentrations of anthropogenic and/or desert dust origin are associated with increased morbidity among children with asthma.

OBJECTIVE

The Mitigating the Health Effects of Desert Dust Storms Using Exposure-Reduction Approaches randomised controlled trial assessed the impact of exposure reduction recommendations, including indoor air filtration, on childhood asthma control during high desert dust storms (DDS) season in Cyprus and Greece.

DESIGN, PARTICIPANTS, INTERVENTIONS AND SETTING

Primary school children with asthma were randomised into three parallel groups: (a) no intervention (controls); (b) outdoor intervention (early alerts notifications, recommendations to stay indoors and limit outdoor physical activity during DDS) and (c) combined intervention (same as (b) combined with indoor air purification with high efficiency particulate air filters in children's homes and school classrooms. Asthma symptom control was assessed using the childhood Asthma Control Test (c-ACT), spirometry (forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC)) and fractional exhaled nitric oxide (FeNO).

RESULTS

In total, 182 children with asthma (age; mean=9.5, SD=1.63) were evaluated during 2019 and 2021. After three follow-up months, the combined intervention group demonstrated a significant improvement in c-ACT in comparison to controls (β=2.63, 95% CI 0.72 to 4.54, p=0.007), which was more profound among atopic children (β=3.56, 95% CI 0.04 to 7.07, p=0.047). Similarly, FEV1% predicted (β=4.26, 95% CI 0.54 to 7.99, p=0.025), the need for any asthma medication and unscheduled clinician visits, but not FVC% and FeNO, were significantly improved in the combined intervention compared with controls.

CONCLUSION

Recommendations to reduce exposure and use of indoor air filtration in areas with high PM pollution may improve symptom control and lung function in children with asthma.

TRIAL REGISTRATION NUMBER

NCT03503812.

A BEAT-PCD consensus statement: a core outcome set for pulmonary disease interventions in primary ciliary dyskinesia

Background

Consistent use of reliable and clinically appropriate outcome measures is a priority for clinical trials, with clear definitions to allow comparability. We aimed to develop a core outcome set (COS) for pulmonary disease interventions in primary ciliary dyskinesia (PCD).

Methods

A multidisciplinary international PCD expert panel was set up. A list of outcomes was created based on published literature. Using a modified three-round e-Delphi technique, the panel was asked to decide on relevant end-points related to pulmonary disease interventions and how they should be reported. First, inclusion of an outcome in the COS was determined. Second, the minimum information that should be reported per outcome. The third round finalised statements. Consensus was defined as ≥80% agreement among experts.

Results

During the first round, experts reached consensus on four out of 24 outcomes to be included in the COS. Five additional outcomes were discussed in subsequent rounds for their use in different subsettings. Consensus on standardised methods of reporting for the COS was reached. Spirometry, health-related quality-of-life scores, microbiology and exacerbations were included in the final COS.

Conclusion

This expert consensus resulted in a COS for clinical trials on pulmonary health among people with PCD.

Airspace Diameter Map-A Quantitative Measurement of All Pulmonary Airspaces to Characterize Structural Lung Diseases

(1) Background: Stereological estimations significantly contributed to our understanding of lung anatomy and physiology. Taking stereology fully 3-dimensional facilitates the estimation of novel parameters. (2) Methods: We developed a protocol for the analysis of all airspaces of an entire lung. It includes (i) high-resolution synchrotron radiation-based X-ray tomographic microscopy, (ii) image segmentation using the free machine-learning tool Ilastik and ImageJ, and (iii) calculation of the airspace diameter distribution using a diameter map function. To evaluate the new pipeline, lungs from adult mice with cystic fibrosis (CF)-like lung disease (βENaC-transgenic mice) or mice with elastase-induced emphysema were compared to healthy controls. (3) Results: We were able to show the distribution of airspace diameters throughout the entire lung, as well as separately for the conducting airways and the gas exchange area. In the pathobiological context, we observed an irregular widening of parenchymal airspaces in mice with CF-like lung disease and elastase-induced emphysema. Comparable results were obtained when analyzing lungs imaged with μCT, sugges-ting that our pipeline is applicable to different kinds of imaging modalities. (4) Conclusions: We conclude that the airspace diameter map is well suited for a detailed analysis of unevenly distri-buted structural alterations in chronic muco-obstructive lung diseases such as cystic fibrosis and COPD.

MEDEA randomised intervention study protocol in Cyprus, Greece and Israel for mitigation of desert dust health effects in adults with atrial fibrillation

INTRODUCTION

Mediterranean countries experience frequent desert dust storm (DDS) events originating from neighbouring Sahara and Arabian deserts, which are associated with significant increase in mortality and hospital admissions, mostly from cardiovascular and respiratory diseases. Short-term exposure to ambient air pollution is considered as a trigger for symptomatic exacerbations of pre-existing paroxysmal atrial fibrillation (AF) and other types of heart arrhythmia. The Mitigating the Health Effects of Desert Dust Storms Using Exposure-Reduction Approaches clinical randomised intervention study in adults with AF is funded by EU LIFE+programme to evaluate the efficacy of recommendations aiming to reduce exposure to desert dust and related heart arrhythmia effects.

METHODS AND ANALYSIS

The study is performed in three heavily exposed to desert dust regions of the Eastern Mediterranean: Cyprus, Israel and Crete-Greece. Adults with paroxysmal AF and implanted pacemaker are recruited and randomised to three parallel groups: (a) no intervention, (b) interventions to reduce outdoor exposure to desert dust, (c) interventions to reduce both outdoor and indoor exposure to particulate matter during desert dust episodes. Eligible participants are enrolled on a web-based platform which communicates, alerts and makes exposure reduction recommendations during DDS events. Exposure changes are assessed by novel tools (smartwatches with Global Positioning System and physical activity sensors, air pollution samplers assessing air quality inside and outside participant's homes, etc). Clinical outcomes include the AF burden expressed as the percentage of time with paroxysmal AF over the total study period, the incidence of ventricular arrhythmia episodes as recorded by the participants' pacemakers or cardioverters/defibrillators and the disease-specific Atrial Fibrillation Effect on QualiTy-of-Life questionnaire.

ETHICS AND DISSEMINATION

Local bioethics' authorities approved the study at all sites, according to national legislations (Cyprus: National Bioethics Committee, Data Protection Commissioner and Ministry of Health; Greece, Scientific Committee and Governing Board of the University General Hospital of Heraklion; Israel: Institutional Review Board ('Helsinki committee') of the Soroka University Medical Center). The findings will be publicised in peer-reviewed scientific journals, in international conferences and in professional websites and newsletters. A summary of the results and participants' interviews will be included in a documentary in English, Greek and Hebrew.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Identifier; NCT03503812.

Observational study of health utilities in adult primary ciliary dyskinesia patients: preliminary data on associations with molecular diagnosis, clinical phenotype and HRQOL measures

Background

Primary ciliary dyskinesia (PCD) is a congenital disorder characterized by chronic respiratory morbidity. To date, there is no information on PCD-specific preference-based quality of life measures such as health utilities (HU). We cross-sectionally assessed HU in adult PCD patients and explored relationships with genotype, phenotype and quality of life (QOL)-PCD scales.

Methods

Diagnostic testing was performed according to international guidelines, while participants completed the visual analog scale (VAS), time trade off (TTO), standard gamble (SG), and EuroQol 5 dimensions (EQ5D) HU instruments, as well as the QOL-PCD questionnaire. Hierarchical regression was used to identify the QOL-PCD scales that are most predictive of HU.

Results

Among 31 patients, median HU are 0.75 (VAS), 0.86 (EQ5D), 0.91 (TTO) and 0.99 (SG). The underlying genotype is not associated with HU measures. VAS and EQ5D are associated with lung function, while TTO and SG values are not sensitive to any of the examined factors. Among the QOL-PCD scales, physical functioning and lower respiratory symptoms explained much of VAS (R²= 0.419) and EQ5D (R²= 0.538) variability.

Conclusions

Our study demonstrates that HU elicitation in PCD is feasible using both direct and indirect methods. Overall, HU scores are relatively high among adult patients, with higher scores observed in SG and TTO, followed by EQ5D and VAS. VAS and EQ5D HU values are sensitive to lung function as well as to QOL-PCD physical functioning and lower respiratory symptom scores.

The disease-specific clinical trial network for Primary Ciliary Dyskinesia (PCD-CTN)

Primary ciliary dyskinesia (PCD) is a rare genetic disorder characterised by impaired mucociliary clearance leading to irreversible lung damage. In contrast to other rare lung diseases like cystic fibrosis (CF), there are only few clinical trials and limited evidence-based treatments. Management is mainly based on expert opinions and treatment is challenging due to a wide range of clinical manifestations and disease severity. To improve clinical and translational research and facilitate development of new treatments, the clinical trial network for PCD (PCD-CTN) was founded in 2020 under the framework of the European Reference Network (ERN)-LUNG PCD Core. Applications from European PCD sites interested in participating in the PCD-CTN were requested. Inclusion criteria consisted of patient numbers, membership of ERN-LUNG PCD Core, use of associated standards of care, experience in PCD and/or CF clinical research, resources to run clinical trials, good clinical practice (GCP) certifications and institutional support. So far, applications from 22 trial sites in 18 European countries have been approved, including >1400 adult and >1600 paediatric individuals with PCD. The PCD-CTN is headed by a coordinating centre and consists of a steering and executive committee, a data safety monitoring board and committees for protocol review, training and standardisation. A strong association with patient organisations and industrial companies are further cornerstones. All participating trial sites agreed on a code of conduct. As CTNs from other diseases have demonstrated successfully, this newly formed PCD-CTN operates to establish evidence-based treatments for this orphan disease and to bring new personalised treatment approaches to patients.

The disease-specific clinical trial network for primary ciliary dyskinesia (PCD-CTN) was built under the framework of the European Reference Network (ERN)-LUNG PCD Core, and operates to establish evidence-based and new personalised treatment for PCDhttps://bit.ly/3sLtC8o

Pediatric asthma symptom control during lockdown for the COVID-19 pandemic in Spring 2020: A prospective community-based study in Cyprus and Greece

OBJECTIVES

To prospectively quantify at the community level changes in asthma symptom control and other morbidity indices, among asthmatic schoolchildren in response to coronavirus disease 2019 (COVID-19) lockdown measures.

METHODS

In Spring 2019 and Spring 2020, we prospectively assessed monthly changes in pediatric asthma control test (c-ACT), asthma medication usage, infections and unscheduled visits for asthma among schoolchildren with active asthma in Cyprus and Greece. We compared asthma symptom control and other morbidity indices before and during lockdown measures, while participants' time spent at home was objectively assessed by wearable sensors.

RESULTS

A total of 119 asthmatic children participated in the study during Spring 2020. Compared to a mean baseline (pre-COVID-19 lockdown) c-ACT score of 22.70, adjusted mean increases of 2.58 (95% confidence interval [CI]: 1.91, 3.26, p < 0.001) and 3.57 (95% CI: 2.88, 4.27, p < 0.001) in the 2nd and 3rd monthly assessments were observed after implementation of lockdown measures. A mean increase in c-ACT score of 0.32 (95% CI: 0.17, 0.47, p < 0.001) was noted per 10% increase in the time spent at home. Improvement was more profound in children with severe asthma, while significant reductions in infections, asthma medication usage and unscheduled visits for asthma were also observed. During Spring 2019, 39 children participated in the study in the absence of lockdown measures and no changes in c-ACT or other indices of disease severity were observed.

CONCLUSIONS

Clinically meaningful improvements in asthma symptom control, among asthmatic schoolchildren were observed during the COVID-19 lockdown measures in Spring 2020. Improvements were independently associated with time spent at home and were more profound in the children with severe asthma.

Demographic characteristics, clinical and laboratory features, and the distribution of pathogenic variants in the CFTR gene in the Cypriot cystic fibrosis (CF) population demonstrate the utility of a national CF patient registry

BACKGROUND

Specialized clinical care for cystic fibrosis (CF) in Cyprus, a small island country, has been implemented since the 1990s. However, only recently, a national CF patient registry has been established for the systematic recording of patients' data. In this study, we aim to present data on the epidemiological, genotypic and phenotypic features of CF patients in the country from the most recent data collection in 2019, with particular emphasis on notable rare or unique cases.

RESULTS

Overall, data from 52 patients are presented, 5 of whom have deceased and 13 have been lost to follow-up in previous years. The mean age at diagnosis was 7.2 ± 12.3 years, and the mean age of 34 alive patients by the end of 2019 was 22.6 ± 13.2 years. Patients most commonly presented at diagnosis with acute or persistent respiratory symptoms (46.2%), failure to thrive or malnutrition (40.4%), and dehydration or electrolyte imbalance (32.7%). Sweat chloride levels were diagnostic (above 60 mmol/L) in 81.8% of examined patients. The most common identified mutation was p.Phe508del (F508del) (45.2%), followed by p.Leu346Pro (L346P) (6.7%), a mutation detected solely in individuals of Cypriot descent. The mean BMI and FEV1 z-scores were 0.2 ± 1.3 and - 2.1 ± 1.7 across all age groups, respectively, whereas chronic Pseudomonas aeruginosa colonization was noted in 26.9% of patients. The majority of patients (74.5%) were eligible to receive at least one of the available CFTR modulator therapies. In 25% of patients we recovered rare or unique genotypic profiles, including the endemic p.Leu346Pro (L346P), the rare CFTR-dup2, the co-segregated c.4200_4201delTG/c.489 + 3A > G, and the polymorphism p.Ser877Ala.

CONCLUSIONS

CF patient registries are particularly important in small or isolated populations, such as in Cyprus, with rare or unique disease cases. Their operation is necessary for the optimization of clinical care provided to CF patients, enabling their majority to benefit from evolving advances in precision medicine.

Implementation of multigene panel NGS diagnosis in the national primary ciliary dyskinesia cohort of Cyprus: An island with a high disease prevalence

We aimed to determine a genetic diagnosis in the national primary ciliary dyskinesia (PCD) cohort of Cyprus, an island with a high disease prevalence. We used targeted next-generation sequencing (NGS) of 39 PCD genes in 48 patients of Greek-Cypriot and other ancestries. We achieved a molecular diagnosis in 74% of the unrelated families tested. We identified 24 different mutations in 11 genes, 12 of which are novel. Homozygosity was more common in Greek-Cypriot than non-Greek-Cypriot patients (88% vs. 46.2%, p = .016). Four mutations (DNAH11:c.5095-2A>G, CFAP300:c.95_103delGCCGGCTCC, TTC25:c.716G>A, RSPH9:c.670+2T>C) were found in 74% of the diagnosed Greek-Cypriot families. Patients with RSPH9 mutations demonstrated higher nasal nitric oxide (57 vs. 15 nl/min, p <.001), higher forced expiratory volume in 1 s (-0.89 vs. -2.37, p = .018) and forced vital capacity (-1.00 vs. -2.16, p = .029) z scores than the rest of the cohort. Targeted multigene-panel NGS is an efficient tool for early diagnosis of PCD, providing insight into genetic disease epidemiology and improved patient stratification.

Use of wearable sensors to assess compliance of asthmatic children in response to lockdown measures for the COVID-19 epidemic

Between March and April 2020, Cyprus and Greece health authorities enforced three escalated levels of public health interventions to control the COVID-19 pandemic. We quantified compliance of 108 asthmatic schoolchildren (53 from Cyprus, 55 from Greece, mean age 9.7 years) from both countries to intervention levels, using wearable sensors to continuously track personal location and physical activity. Changes in 'fraction time spent at home' and 'total steps/day' were assessed with a mixed-effects model adjusting for confounders. We observed significant mean increases in 'fraction time spent at home' in Cyprus and Greece, during each intervention level by 41.4% and 14.3% (level 1), 48.7% and 23.1% (level 2) and 45.2% and 32.0% (level 3), respectively. Physical activity in Cyprus and Greece demonstrated significant mean decreases by - 2,531 and - 1,191 (level 1), - 3,638 and - 2,337 (level 2) and - 3,644 and - 1,961 (level 3) total steps/day, respectively. Significant independent effects of weekends and age were found on 'fraction time spent at home'. Similarly, weekends, age, humidity and gender had an independent effect on physical activity. We suggest that wearable technology provides objective, continuous, real-time location and activity data making possible to inform in a timely manner public health officials on compliance to various tiers of public health interventions during a pandemic.

Evaluation of a multiple breath nitrogen washout system in children

INTRODUCTION

The multiple breath nitrogen washout (MBW) test offers a sensitive measure of airway function. In this study we aim to (a) assess the validity of the EasyOne Pro LAB (MBW_ndd ) in an in vitro lung model, (b) assess the feasibility, repeatability, and reproducibility of MBW_ndd and (c) compare outcomes with the Exhalyzer D (MBW_EM ) and body plethysmography.

METHODS

In vitro, functional residual capacity (FRC) measurements were assessed using a lung model under quasi-physiological conditions and compared to measured FRC. In vivo plethysmography and MBW were performed in a prospective study of children at two visits (n = 45 healthy; n = 41 cystic fibrosis [CF]). Bland-Altman plots were used to compare agreement between FRC and lung clearance index (LCI) measurements.

RESULTS

In vitro FRC_ndd measurements were repeatable but lung volumes were underestimated (mean relative difference -5.4% (limits of agreement [LA] -9.6%; -1.1%), 95% confidence interval (CI) -6.27; -4.45). In vivo, compared to plethysmography, FRC_ndd was consistently lower (-19.3% [-40.5; 1.9], 95% CI [-23.9; -14.7]), and showed a volume dependency. LCI_ndd values were also higher in children with smaller lung volumes. The within-test coefficient of variation of the FRC_ndd and LCI_ndd were 4.9% in health, and 5.6% and 6.9% in CF respectively. LCI_ndd was reproducible between-visits (mean relative difference [LA] -3.7% [-14.8, -7.5; 95% CI -6.6; -0.73] in health [n = 17] and 0.34% [-13.2, 22.8; 95% CI -5.0; 5.69] in CF [n = 23]). When calculated using the same algorithm, LCI_ndd was similar to LCI_EM in health.

CONCLUSIONS

MBW_ndd measurements are feasible, repeatable, and reproducible, however, MBW-derived outcomes are not interchangeable with MBW_EM .

Normative data for multiple breath washout outcomes in school-aged Caucasian children

Background

The multiple breath nitrogen washout (N2MBW) technique is increasingly used to assess the degree of ventilation inhomogeneity in school-aged children with lung disease. However, reference values for healthy children are currently not available. The aim of this study was to generate reference values for N2MBW outcomes in a cohort of healthy Caucasian school-aged children.

Methods

N2MBW data from healthy Caucasian school-age children between 6 and 18 years old were collected from four experienced centres. Measurements were performed using an ultrasonic flowmeter (Exhalyzer D, Eco Medics AG, Duernten, Switzerland) and were analysed with commercial software (Spiroware version 3.2.1, Eco Medics AG). Normative values and upper limits of normal (ULN) were generated for lung clearance index (LCI) at 2.5% (LCI2.5%) and at 5% (LCI5%) of the initial nitrogen concentration and for moment ratios (M1/M0 and M2/M0). A prediction equation was generated for functional residual capacity (FRC).

Results

Analysis used 485 trials from 180 healthy Caucasian children aged from 6 to 18 years old. While LCI increased with age, this increase was negligible (0.04 units·year–1 for LCI2.5%) and therefore fixed ULN were defined for this age group. These limits were 7.91 for LCI2.5%, 5.73 for LCI5%, 1.75 for M1/M0 and 6.15 for M2/M0, respectively. Height and weight were found to be independent predictors of FRC.

Conclusion

We report reference values for N2MBW outcomes measured on a commercially available ultrasonic flowmeter device (Exhalyzer D, Eco Medics AG) in healthy school-aged children to allow accurate interpretation of ventilation distribution outcomes and FRC in children with lung disease.

A multi-scale model of gas transport in the lung to study heterogeneous lung ventilation during the multiple-breath washout test

The multiple-breath washout (MBW) is a lung function test that measures the degree of ventilation inhomogeneity (VI). The test is used to identify small airway impairment in patients with lung diseases like cystic fibrosis. However, the physical and physiological factors that influence the test outcomes and differentiate health from disease are not well understood. Computational models have been used to better understand the interaction between anatomical structure and physiological properties of the lung, but none of them has dealt in depth with the tracer gas washout test in a whole. Thus, our aim was to create a lung model that simulates the entire MBW and investigate the role of lung morphology and tissue mechanics on the tracer gas washout procedure. To this end, we developed a multi-scale lung model to simulate the inert gas transport in airways of all size. We then applied systematically different modifications to geometrical and mechanical properties of the lung model (compliance, residual airway volume and flow resistance) which have been associated with VI. The modifications were applied to distinct parts of the model, and their effects on the gas distribution within the lung and on the gas concentration profile were assessed. We found that variability in compliance and residual volume of the airways, as well as the spatial distribution of this variability in the lung had a direct influence on gas distribution among airways and on the MBW pattern (washout duration, characteristic concentration profile during each expiration), while the effects of variable flow resistance were negligible. Based on these findings, it is possible to classify different types of inhomogeneities in the lung and relate them to specific features of the MBW pattern, which builds the basis for a more detailed association of lung function and structure.

Obstructive lung diseases, like cystic fibrosis or primary ciliary dyskinesia, lead to inhomogeneous ventilation. The degree of observed inhomogeneity represents a clinical measure for the progression of the disease. The multiple-breath washout (MBW) is a lung function test that measures this inhomogeneity in the lung. However, the factors that influence the results of the test and differentiate between health and disease are not well understood. Computational models help us to understand better the relation between anatomical structure and physiological properties of the lung, but none of them has dealt in depth with the MBW test in whole. Our aim was to create a lung model that simulates the entire MBW test and study the role of lung structure and tissue mechanics on the washout procedure. We developed a multi-scale lung model to simulate the inert gas transport in all airways including the gas exchange area. Our model offers the opportunity to understand the ventilation distribution in the healthy lung. It can also mimic certain patterns of lung disease by applying modifications in mechanical properties out of the physiological limits. Thus, it can be used to study MBW characteristics in health and disease.

An innovative lung model for multiple breath washout testing in health and disease

BACKGROUND

Multiple breath washout (MBW) is a lung function test that identifies the degree of ventilation inhomogeneity (VI) in the lungs. In vitro validation of MBW devices is recommended. So far, plastic lung models for MBW validation ignored variable degrees of VI. Our primary aim was to create a plastic lung model applicable for physiological lung volumes and variable VI.

METHODS

A plastic box divided in two chambers was filled with water and ventilated in various lung volumes and respiratory rates. A ventilator was used for efficient gas distribution (model with low VI). An additional divider was inserted to create a model with high VI. The model was connected to commercial MBW devices and measurements were performed using different tracer gases and conditions. Primary outcome was the precision of generated functional residual capacity (FRC) and the ability to generate variable VI. The latter was estimated by lung clearance index (LCI) and expiratory phase III slopes (SIII). LCI was also compared to a mathematical model.

FINDINGS

The intra-test variability for FRC was minimal, mean(SD) coefficient of variation 0.96(0.63)%, using different tracer gases under different conditions. Compared to the model with low VI, in the model with high VI LCI and washout SIII were significantly increased. LCI compared well to the mathematical model.

INTERPRETATION

This novel lung model shows excellent precision in lung volumes and VI estimates independent of tracer gases and conditions. The model can mimic the lungs of patients with uneven gas distribution.

Variability of Tidal Breathing Parameters in Preterm Infants and Associations with Respiratory Morbidity during Infancy: A Cohort Study

OBJECTIVE

To test whether low variability of tidal volume (V_T) and capnographic indices are predictive of subsequent respiratory morbidity in preterm infants.

STUDY DESIGN

In a birth cohort of 133 preterm infants, lung function was performed at 44 weeks postmenstrual age. Associations between the coefficient of variation (CV) of V_T (CV_VT) and of expired CO₂ volume per breath (CV_VE,CO2) with rehospitalization, wheeze, and inhalation therapy during infancy were assessed using logistic regression. Area under the curve (AUC) analysis was used to assess whether outcome prediction using bronchopulmonary dysplasia (BPD) classification was enhanced by CV_VT or CV_VE,CO2.

RESULTS

For each IQR decrease in CV_VT (range, 4%-35%) and CV_VE,_CO2 (range, 5%-40%), the OR for rehospitalization increased by 2.25 (95% CI, 1.21-4.20) and 2.31 (95% CI, 1.20-4.45), respectively. The predictive value of BPD for rehospitalization was improved when CV_VT or CV_VE,CO2 was added to the model, with the AUC increasing from 0.56 to 0.66 in both models. No association was found for the other outcomes.

CONCLUSIONS

Compared with BPD classification alone, including near-term variability of tidal breathing parameters improves the prediction of rehospitalization in infancy. These findings may inform parent counseling and monitoring strategies in preterm infants.

Dynamics of respiratory symptoms during infancy and associations with wheezing at school age

Children with frequent respiratory symptoms in infancy have an increased risk for later wheezing, but the association with symptom dynamics is unknown. We developed an observer-independent method to characterise symptom dynamics and tested their association with subsequent respiratory morbidity. In this birth-cohort of healthy neonates, we prospectively assessed weekly respiratory symptoms during infancy, resulting in a time series of 52 symptom scores. For each infant, we calculated the transition probability between two consecutive symptom scores. We used these transition probabilities to construct a Markov matrix, which characterised symptom dynamics quantitatively using an entropy parameter. Using this parameter, we determined phenotypes by hierarchical clustering. We then studied the association between phenotypes and wheezing at 6 years. In 322 children with complete data for symptom scores during infancy (16 864 observations), we identified three dynamic phenotypes. Compared to the low-risk phenotype, the high-risk phenotype, defined by the highest entropy parameter, was associated with an increased risk of wheezing (odds ratio (OR) 3.01, 95% CI 1.15-7.88) at 6 years. In this phenotype, infants were more often male (64%) and had been exposed to environmental tobacco smoke (31%). In addition, more infants had siblings (67%) and attended childcare (38%). We describe a novel method to objectively characterise dynamics of respiratory symptoms in infancy, which helps identify abnormal clinical susceptibility and recovery patterns of infant airways associated with persistent wheezing.

Comparison of different analysis algorithms to calculate multiple-breath washout outcomes

Lung clearance index (LCI) is the main outcome of the multiple-breath washout (MBW) test. Current recommendations for LCI acquisition are based on low-grade evidence. The aim of this study was to challenge those recommendations using alternative methods for LCI analysis. Nitrogen MBW measurements from school-aged children, 20 healthy controls, 20 with cystic fibrosis (CF) and 17 with primary ciliary dyskinesia (PCD), were analysed using 1) current algorithms (standard), 2) three alternative algorithms to detect with higher precision the end of MBW testing and 3) two alternative algorithms to determine exhaled tracer gas concentrations. LCI values, intra-test repeatability, and ability to discriminate between health and lung disease were compared between these methods. The analysis methods strongly influenced LCI (mean±sd overall differences (%) between standard and alternative analysis methods: -4.9±5.7%; range: -66-19%), but did not improve intra-test variability. Discrimination between health and disease was comparable as areas under the receiver operator curves were not greater than that from standard analysis. This study supports current recommendations for LCI calculation in children. Alternative methods influence LCI estimates and hamper comparability between MBW setups. Alternative algorithms, whenever used, should be carefully reported.

Efficacy and safety of the combination fluticasone propionate plus salmeterol in asthmatic preschoolers: An observational study

BACKGROUND

Inhaled Corticosteroids (ICS) are the cornerstone of asthma management in pediatric patients. However, in some cases, asthma is not adequately controlled on ICS alone. Long-acting beta₂-agonists (LABA) are one of the available additional therapies but their use has rarely been studied among children younger than 5 years.

OBJECTIVE

The aim of this observational study was to evaluate the efficacy and safety of the combination of fluticasone propionate and salmeterol (FP/SA) in asthmatic children younger than 5 years of age.

METHODS

A retrospective study of 796 children under the age of 5 years (2.87 ± 1.22 years, 64.2% males), who were treated with FP/SA was conducted. Hospitalization rates, frequency of wheezing, exercise induced asthma, nocturnal wheeze and drug-related side-effects were recorded through children's medical records.

RESULTS

The children had previously received short-acting β₂-agonists (73%), ICS (17%), montelukast (1%), and ICS with montelukast (2%). Mean duration of therapy with FP/SA was 12.45 ± 9.14 months. After adjusting for age, gender, and duration of treatment, a 89% reduction was recorded in annual hospitalization rates (from 27.13% before treatment to 3.01% after FP/SA therapy, p < 0.001), a 71% reduction in incidence of exercise-induced asthma (36.8% vs. after 10.6%, p < 0.001), a 81% reduction in nocturnal asthma (33.7% vs. after: 6.4%, p < 0.001), as well as in frequency of wheezing (p < 0.01),. No previous treatment carry-on effect was observed. No major drug-related side-effects occurred in the study group.

CONCLUSIONS

Combination therapy (FP/SA) is well-tolerated and highly effective in asthmatic children under the age of 5 years.

Infant multiple breath washout using a new commercially available device: Ready to replace the previous setup?

INTRODUCTION

Multiple breath washout (MBW) is a sensitive test to measure lung volumes and ventilation inhomogeneity from infancy on. The commonly used setup for infant MBW, based on ultrasonic flowmeter, requires extensive signal processing, which may reduce robustness. A new setup may overcome some previous limitations but formal validation is lacking.

AIM

We assessed the feasibility of infant MBW testing with the new setup and compared functional residual capacity (FRC) values of the old and the new setup in vivo and in vitro.

METHODS

We performed MBW in four healthy infants and four infants with cystic fibrosis, as well as in a Plexiglas lung simulator using realistic lung volumes and breathing patterns, with the new (Exhalyzer D, Spiroware 3.2.0, Ecomedics) and the old setup (Exhalyzer D, WBreath 3.18.0, ndd) in random sequence.

RESULTS

The technical feasibility of MBW with the new device-setup was 100%. Intra-subject variability in FRC was low in both setups, but differences in FRC between the setups were considerable (mean relative difference 39.7%, range 18.9; 65.7, P = 0.008). Corrections of software settings decreased FRC differences (14.0%, -6.4; 42.3, P = 0.08). Results were confirmed in vitro.

CONCLUSION

MBW measurements with the new setup were feasible in infants. However, despite attempts to correct software settings, outcomes between setups were not interchangeable. Further work is needed before widespread application of the new setup can be recommended.

Elevated lung clearance index in infants with cystic fibrosis shortly after birth

It is not known at what age lung function impairment may arise in children with cystic fibrosis (CF). We assessed lung function shortly after birth in infants with CF diagnosed by newborn screening.We performed infant lung function measurements in a prospective cohort of infants with CF and healthy controls. We assessed lung clearance index (LCI), functional residual capacity (FRC) and tidal breathing parameters. The primary outcome was prevalence and severity of abnormal lung function (±1.64 z-scores) in CF.We enrolled 53 infants with CF (mean age 7.8 weeks) and 57 controls (mean age 5.2 weeks). Compared to controls, LCI and FRC were elevated (mean difference 0.30, 95% CI 0.02-0.60; p=0.034 and 14.5 mL, 95% CI 7.7-21.3 mL; p<0.001, respectively), while ratio of time to peak tidal expiratory flow to expiratory time was decreased in infants with CF. In 22 (41.5%) infants with CF, either LCI or FRC exceeded 1.64 z-scores; three infants had both elevated LCI and FRC.Shortly after birth, abnormal lung function is prevalent in CF infants. Ventilation inhomogeneity or hyperinflation may serve as noninvasive markers to monitor CF lung disease and specific treatment effects, and could thus be used as outcome parameters for future intervention studies in this age group.

Interrupter technique in infancy: Higher airway resistance and lower short-term variability in preterm versus term infants

BACKGROUND

In preschool children, measurement of airway resistance using interrupter technique (Rint) is feasible to assess the degree of bronchial obstruction. Although some studies measured Rint in infancy, values of Rint and its variability in preterm infants are unknown. In this study, Rint and its variability was measured at infancy and compared between healthy term and preterm infants.

METHODS

High quality Rint measurements in term (n = 50) and preterm (n = 48) infants were obtained at postmenstrual age of 42-50 weeks in two study centers in Switzerland. Intra-measurement variability of Rint in one measurement and inter-measurement variability between two subsequent measurements was assessed by coefficient of variation (CV).

RESULTS

Mean Rint in term infants was 4.2 ± (SD; 1.9) kPa · s · L^-1 and in preterm infants was 5.6 ± (2.8) kPa · s · L^-1 . Mean CV in term infants was 29.6 ± (14.9)% and in preterm infants was 20.2 ± (8.4)%. Rint was significantly lower (95%CI -2.31 to -0.38; P = 0.007) and CV significantly higher (95%CI 4.53-14.3; P < 0.001) in term compared to preterm infants. There were no differences in mean Rint and mean CV between the first and the second measurement obtained in a subgroup of term (n = 24, 48%) and preterm (n = 22, 45%) infants.

CONCLUSIONS

Our results suggest that differences in airway mechanics between term and preterm infants can be assessed with the interrupter technique during early infancy. Before clinical application of Rint measurements in this age group, reasons underlying the variability of measurements should be further investigated.

Lung clearance index and moment ratios at different cut-off values in infant multiple-breath washout measurements

BACKGROUND

Multiple-breath washout (MBW) is increasingly used for infant lung function testing. Current guidelines recommend calculating lung clearance index (LCI) and functional residual capacity (FRC) at 2.5% of normalized tracer gas concentration, without clear recommendation for moment ratios (MR). Whether the 2.5% cut-off has the highest discriminative power to detect ventilation inhomogeneity in infants with lung diseases is unknown.

METHODS

We used sulfur-hexafluoride MBW measurements from 32 infants with cystic fibrosis, 32 preterm infants, and 32 healthy controls at postmenstrual age of 41-54 weeks. We compared the discriminative power to detect pathological values above the upper limit of normal for 12 different cut-offs between 20% and 1.5% for first and second MR (MR1, MR2), LCI, and FRC.

RESULTS

MR and LCI results changed significantly at different cut-offs. Mean MR2 in infants with cystic fibrosis increased from 2.4 to 7.2 units between 20% and 1.5% SF₆ . The ability of MR and LCI to discriminate between health and disease increased significantly with lower cut-offs. The 1.5% cut-off showed highest discriminative power: in infants with cystic fibrosis pathological MR2 values were found in 27 out of 89 (30%) and for LCI in 28/89 (32%). In preterm infants, pathological MR2 values were detected in 39 out of 73 (53%), and for LCI in 35/73 (48%). FRC remained stable throughout the washout.

CONCLUSION

In infants, the diagnostic performance of MBW strongly depends on the point of analysis. The cut-off with the highest discriminative power to detect ventilation inhomogeneity in infants with cystic fibrosis and after preterm birth was at 1.5% tracer gas concentration. Pediatr Pulmonol. 2016;51:1373-1381. © 2016 Wiley Periodicals, Inc.

False normal Lung Clearance Index in infants with cystic fibrosis due to software algorithms

BACKGROUND

Lung clearance index (LCI), a marker of ventilation inhomogeneity, is elevated early in children with cystic fibrosis (CF). However, in infants with CF, LCI values are found to be normal, although structural lung abnormalities are often detectable. We hypothesized that this discrepancy is due to inadequate algorithms of the available software package.

AIM

Our aim was to challenge the validity of these software algorithms.

METHODS

We compared multiple breath washout (MBW) results of current software algorithms (automatic modus) to refined algorithms (manual modus) in 17 asymptomatic infants with CF, and 24 matched healthy term-born infants. The main difference between these two analysis methods lies in the calculation of the molar mass differences that the system uses to define the completion of the measurement.

RESULTS

In infants with CF the refined manual modus revealed clearly elevated LCI above 9 in 8 out of 35 measurements (23%), all showing LCI values below 8.3 using the automatic modus (paired t-test comparing the means, P < 0.001). Healthy infants showed normal LCI values using both analysis methods (n = 47, paired t-test, P = 0.79). The most relevant reason for false normal LCI values in infants with CF using the automatic modus was the incorrect recognition of the end-of-test too early during the washout.

CONCLUSION

We recommend the use of the manual modus for the analysis of MBW outcomes in infants in order to obtain more accurate results. This will allow appropriate use of infant lung function results for clinical and scientific purposes.

SLC26A9-mediated chloride secretion prevents mucus obstruction in airway inflammation

Asthma is a chronic condition with unknown pathogenesis, and recent evidence suggests that enhanced airway epithelial chloride (Cl-) secretion plays a role in the disease. However, the molecular mechanism underlying Cl- secretion and its relevance in asthma pathophysiology remain unknown. To determine the role of the solute carrier family 26, member 9 (SLC26A9) Cl- channel in asthma, we induced Th2-mediated inflammation via IL-13 treatment in wild-type and Slc26a9-deficient mice and compared the effects on airway ion transport, morphology, and mucus content. We found that IL-13 treatment increased Cl- secretion in the airways of wild-type but not Slc26a9-deficient mice. While IL-13-induced mucus overproduction was similar in both strains, treated Slc26a9-deficient mice exhibited airway mucus obstruction, which did not occur in wild-type controls. In a study involving healthy children and asthmatics, a polymorphism in the 3' UTR of SLC26A9 that reduced protein expression in vitro was associated with asthma. Our data demonstrate that the SLC26A9 Cl- channel is activated in airway inflammation and suggest that SLC26A9-mediated Cl- secretion is essential for preventing airway obstruction in allergic airway disease. These results indicate that SLC26A9 may serve as a therapeutic target for airway diseases associated with mucus plugging.

mCLCA3 does not contribute to calcium-activated chloride conductance in murine airways

Ca(2+)-activated Cl(-) channels (CaCCs) contribute to airway Cl(-) and fluid secretion, and were implicated in the modulation of disease severity and as a therapeutic target in cystic fibrosis (CF). Previous in vitro studies suggested that members of the CLCA gene family, including the murine mCLCA3, contribute to CaCCs. However, the role of mCLCA3 in ion transport in native airway epithelia has not been studied, to the best of our knowledge. In this study, we used mCLCA3-deficient mice and determined bioelectric properties in freshly excised tracheal tissue, airway morphology, and gene expression studies, to determine the role of mCLCA3 in airway ion transport and airway structure. Bioelectric measurements did not detect any differences in basal short-circuit current, amiloride-sensitive Na(+) absorption, cyclic adenosine monophosphate-dependent Cl(-) secretion, and activation of Ca(2+)-activated (uridine-5'-triphosphate-mediated) Cl(-) secretion in mCLCA3-deficient mice compared with wild-type mice. Moreover, no histological changes were observed in the respiratory tract or any other tissues of mCLCA3-deficient mice when compared with wild-type control mice. The intratracheal instillation of IL-13 produced an approximately 30-fold up-regulation of mCLCA3 transcripts without inducing CaCC activity in wild-type airways, and induced goblet-cell hyperplasia and mucin gene expression to similar levels in both genotypes. Further, multiple specific reverse-transcriptase quantitative PCR assays for other CaCC candidates, including mCLCA1, mCLCA2, mCLCA4, mCLCA5, mCLCA6, mCLCA7, mBEST1, mBEST2, mCLC4, mTTYH3, and mTMEM16A, failed to identify the differential expression of genes in the respiratory tract that may compensate for a lack of mCLCA3 function. Together, these findings argue against a role of mCLCA3 in CaCC-mediated Cl(-) secretion in murine respiratory epithelia.

Allergic airway inflammation induces a pro-secretory epithelial ion transport phenotype in mice

The airway epithelium is a central effector tissue in allergic inflammation and T-helper cell (Th) type 2-driven epithelial responses, such as mucus hypersecretion contribute to airflow obstruction in allergic airway disease. Previous in vitro studies demonstrated that Th2 cytokines also act as potent modulators of epithelial ion transport and fluid secretion, but the in vivo effect of allergic inflammation on airway ion transport remains unknown. We, therefore, induced allergic inflammation by intratracheal instillation of Aspergillus fumigatus extract or interleukin-13 in mice and determined effects on ion transport in native tracheal and bronchial tissues. We demonstrate that allergic inflammation enhanced basal Cl(-) secretion in both airway regions and inhibited epithelial Na(+) channel (ENaC)-mediated Na(+) absorption and increased Ca²(+)-dependent Cl(-) secretion in bronchi. Allergen-induced alterations in bronchial ion transport were associated with reduced transcript levels of α-, β- and γENaC, and were largely abrogated in signal transducer and activator of transcription (Stat)6(-/-) mice. Our studies demonstrate that Th2-dependent airway inflammation produced a pro-secretory ion transport phenotype in vivo, which was largely Stat6-dependent. These results suggest that Th2-mediated fluid secretion may improve airway surface hydration and clearance of mucus that is hypersecreted in allergic airway diseases such as asthma, and identify epithelial Stat6 signalling as a potential therapeutic target to promote mucus hydration and airway clearance.