Airway function in infants newly diagnosed with cystic fibrosis

Levelling the playing field through the London Network of the UK clinical trials accelerator platform

Cystic fibrosis (CF) is a multisystem, genetic disease with a significantly reduced life expectancy. Despite substantial progress in therapies in the last 10-15 years, there is still no cure. There are dozens of drugs in the development pipeline and multiple clinical trials are being conducted across the globe. The UK Cystic Fibrosis Trust's (CFT) Clinical Trials Accelerator Platform (CTAP) is a national initiative bringing together 25 UK based CF centres to support the CF community in accessing and participating in CF clinical trials. CTAP enables more CF centres to run a broader portfolio of trials and increases the range of CF studies available for UK patients. There are four large specialist CF centres based in London, all within a small geographical region as well as two smaller centres which deliver CF care. At the launch of CTAP, these centres formed a sub-network in a consortium-style collaboration. The purpose of the network was to ensure equity of access to trials for patients across the UK's capital, and to share experience and knowledge. Four years into the programme we have reviewed our practices through working group meetings and an online survey. We sought to identify strengths and areas for improvement. We share our findings here, as we believe they are relevant to others delivering research in regions outside of London and in other chronic diseases.

CFTR modulator therapy: transforming the landscape of clinical care in cystic fibrosis

Following discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in 1989 and subsequent elucidation of the varied CFTR protein abnormalities that result, a new era of cystic fibrosis management has emerged-one in which scientific principles translated from the bench to the bedside have enabled us to potentially treat the basic defect in the majority of children and adults with cystic fibrosis, with a resultant burgeoning adult cystic fibrosis population. However, the long-term effects of these therapies on the multiple manifestations of cystic fibrosis are still under investigation. Understanding the effects of modulators in populations excluded from clinical trials is also crucial. Furthermore, establishing appropriate disease measures to assess efficacy in the youngest potential trial participants and in those whose post-modulator lung function is in the typical range for people without chronic lung disease is essential for continued drug development. Finally, recognising that a health outcome gap has been created for some people and widened for others who are not eligible for, cannot tolerate, or do not have access to modulators is important.

The effect of CFTR modulators on structural lung disease in cystic fibrosis

Background: Newly developed quantitative chest computed tomography (CT) outcomes designed specifically to assess structural abnormalities related to cystic fibrosis (CF) lung disease are now available. CFTR modulators potentially can reduce some structural lung abnormalities. We aimed to investigate the effect of CFTR modulators on structural lung disease progression using different quantitative CT analysis methods specific for people with CF (PwCF). Methods: PwCF with a gating mutation (Ivacaftor) or two Phe508del alleles (lumacaftor-ivacaftor) provided clinical data and underwent chest CT scans. Chest CTs were performed before and after initiation of CFTR modulator treatment. Structural lung abnormalities on CT were assessed using the Perth Rotterdam Annotated Grid Morphometric Analysis for CF (PRAGMA-CF), airway-artery dimensions (AA), and CF-CT methods. Lung disease progression (0-3 years) in exposed and matched unexposed subjects was compared using analysis of covariance. To investigate the effect of treatment in early lung disease, subgroup analyses were performed on data of children and adolescents aged <18 years. Results: We included 16 modulator exposed PwCF and 25 unexposed PwCF. Median (range) age at the baseline visit was 12.55 (4.25-36.49) years and 8.34 (3.47-38.29) years, respectively. The change in PRAGMA-CF %Airway disease (-2.88 (-4.46, -1.30), p = 0.001) and %Bronchiectasis extent (-2.07 (-3.13, -1.02), p < 0.001) improved in exposed PwCF compared to unexposed. Subgroup analysis of paediatric data showed that only PRAGMA-CF %Bronchiectasis (-0.88 (-1.70, -0.07), p = 0.035) improved in exposed PwCF compared to unexposed. Conclusion: In this preliminary real-life retrospective study CFTR modulators improve several quantitative CT outcomes. A follow-up study with a large cohort and standardization of CT scanning is needed to confirm our findings.

Going the Extra Mile: Why Clinical Research in Cystic Fibrosis Must Include Children

This is an exciting time for research and novel drug development in cystic fibrosis. However, rarely has the adage, “Children are not just little adults” been more relevant. This article is divided into two main sections. In the first, we explore why it is important to involve children in research. We discuss the potential benefits of understanding a disease and its treatment in children, and we highlight that children have the same legal and ethical right to evidence-based therapy as adults. Additionally, we discuss why extrapolation from adults may be inappropriate, for example, medication pharmacokinetics may be different in children, and there may be unpredictable adverse effects. In the second part, we discuss how to involve children and their families in research. We outline the importance and the complexities of selecting appropriate outcome measures, and we discuss the role co-design may have in improving the involvement of children. We highlight the importance of appropriate staffing and resourcing, and we outline some of the common challenges and possible solutions, including practical tips on obtaining consent/assent in children and adolescents. We conclude that it is unethical to simply rely on extrapolation from adult studies because research in young children is challenging and that research should be seen as a normal part of the paediatric therapeutic journey.

An observational study of the lung clearance index throughout childhood in cystic fibrosis: early years matter

The London Cystic Fibrosis Collaboration (LCFC) has prospectively followed a clinically diagnosed cohort of infants with cystic fibrosis (CF) born in South East England since 1999 [1–4]. Over the past 20 years, the LCFC has obtained comprehensive measures of lung function and structure, including measures of ventilation inhomogeneity (lung clearance index (LCI)) and high-resolution computed tomography (HRCT) scans. By pre-school age, 73% of this cohort had LCI above the limits of normal, compared with 7% with abnormal forced expiratory volume in 0.5 seconds (FEV_0.5) [1]. Children with elevated LCI during pre-school years also had worse lung function at early school age [2]. The aim of this study was to investigate how LCI changes across childhood to better understand to what extent LCI results at pre-school age are an indicator of lung disease severity in adolescence.

Lung clearance index (LCI) in the early years was associated with LCI during adolescence in children with cystic fibrosis. Pre-school LCI may help to identify children in whom treatment could be intensified.https://bit.ly/2yKyMbM

The role of inflammation in cystic fibrosis pulmonary exacerbations

INTRODUCTION

Cystic Fibrosis pulmonary exacerbations are critical events in the lives of people with CF that have deleterious effects on lung function, quality of life, and life expectancy. There are significant unmet needs in the management of exacerbations. We review here the associated inflammatory changes that underlie these events and are of interest for the development of biomarkers of exacerbation.

AREAS COVERED

Inflammatory responses in CF are abnormal and contribute to a sustained proinflammatory lung microenvironment, abundant in proinflammatory mediators and deficient in counter-regulatory mediators that terminate and resolve inflammation. There is increasing interest in these inflammatory pathways to discover novel biomarkers for pulmonary exacerbation management. In this review, we explore the inflammatory changes occurring during intravenous antibiotic therapy for exacerbation and how they may be applied as biomarkers to guide exacerbation therapy. A literature search was conducted using the PubMed database in February 2020.

EXPERT OPINION

Heterogeneity in inflammatory responses to treatment of a pulmonary exacerbation, a disease process with complex pathophysiology, limits the clinical utility of individual biomarkers. Biomarker panels may be a more successful strategy to capture informative changes within the CF population to improve pulmonary exacerbation management and outcomes.

Clinical utility of surveillance computed tomography scans in infants with cystic fibrosis

BACKGROUND

In cystic fibrosis (CF), irreversible lung disease arises in early life, and is often asymptomatic and unrecognised. Chest computed tomography (CT) scans have been used to detect asymptomatic lung disease in research; however, the clinical utility of chest CT is unknown. This study aimed to determine the effect of surveillance CT in early life on the clinical management of patients with CF.

WORKING HYPOTHESIS

Surveillance CT in early life changes the management of patients with CF.

METHODS

A medical record review of patients in the AREST-CF cohort who had chest CT at 1 and 3 years of age was performed. Information extracted included CT scan findings and the effect of CT results on clinical management.

RESULTS

The chest CT scans and records of 50 subjects with CF were reviewed. The majority of CT scans (n = 75; 75%) were abnormal. N = 31 (31%) of scans overall led to a direct change in management. The number of CT scans needed to be performed to lead to a treatment change was 3.2. The majority (n = 18, 58%) of changes in management were prompted by the finding of bronchiectasis.

CONCLUSION

To the authors knowledge, this is the first study to highlight that early life surveillance CT frequently results in changes in clinical management, and hence may have a role beyond research and in routine care. If this can be shown to contribute to improved outcomes (such as reduced rates of bronchiectasis), then, as radiation doses diminish, chest CT could have an important clinical role.

Variability of lung clearance index in clinically stable cystic fibrosis lung disease in school age children

BACKGROUND

Data on long term variability of Lung Clearance Index (LCI) in Cystic Fibrosis (CF) is urgently needed to guide test result interpretation. Our aim was to evaluate LCI variability in clinically stable CF lung disease in school age children.

METHODS

Paediatric patients, aged 6 to 17years, attending the outpatient CF clinic performed Multiple Breath Nitrogen Washout (Exhalyzer® D) and spirometry every third month over a period of one year. Clinical stability was assessed by the Cystic Fibrosis Clinical Score (CFCS) at each visit.

RESULTS

Twentyfive children were recruited: baseline median (range) FEV₁% pred. 91 (55-122)%, LCI 9.1 (6.4-18.6), CFCS 15 (12-23). A total of 107 visits were included in the study, of which 93% were defined as clinically stable. In clinically stable visits, within-subject variability of LCI and FEV₁% pred. were 10% and 16%, respectively. The upper limit of normal (ULN, 95% percentile) of LCI variability during clinical stability was 17%.

CONCLUSIONS

LCI within-subject variability was low and comparable to FEV₁% pred. which strengthen the use of LCI to monitor lung disease progression in CF patients. An increase in LCI >17% compared to previous LCI-measurement in clinically stable CF patients may therefore indicate early lung disease progression.

Prerequisites for a dry powder inhaler for children with cystic fibrosis

Correct inhalation technique is essential for effective use of dry powder inhalers (DPIs), as their effectiveness largely depends on the patient's inhalation manoeuvre. Children are an especially challenging target population for DPI development due to the large variability in understanding and inspiratory capacities. We previously performed a study in which we determined the prerequisites for a paediatric DPI in a mostly healthy paediatric population, for which we used an empty test inhaler with variable internal airflow resistance and mouthpiece. In the current study we investigated what specifications are required for a DPI for children with cystic fibrosis (CF), for which we expanded on our previous findings. We recorded flow profiles of 35 children with CF (aged 4.7-14.7 years) at three airflow resistances (0.031-0.045 kPa0.5.min.L-1) from which various inspiratory parameters were computed. Obstructions in the mouth during inhalation were recorded with a sinuscope. All children were able to perform a correct inhalation manoeuvre, although video analysis showed that children did not place the inhaler correctly in the mouth in 17% of the cases. No effect was found of medium to high airflow resistance on total inhaled volume, which implies that the whole resistance range tested is suitable for children with CF aged 4-14 years. No effect could be established of either mouthpiece design or airflow resistance on the occurrence of obstructions in the mouth cavity. This study confirms our previous conclusion that the development of DPIs specifically for children is highly desired. Such a paediatric DPI should function well at 0.5 L inhaled volume and a peak inspiratory flow rate of 20 to 30 L/min, depending on the internal airflow resistance. This resistance can be increased up to 0.045 kPa0.5.min.L-1 (medium-high) to reduce oropharyngeal deposition. A higher resistance may be less favourable due to its compromising effect on PIF and thereby on the energy available for powder dispersion.

Progression of Lung Disease in Preschool Patients with Cystic Fibrosis

RATIONALE

Implementation of intervention strategies to prevent lung damage in early cystic fibrosis (CF) requires objective outcome measures that capture and track lung disease.

OBJECTIVES

To define the utility of the Lung Clearance Index (LCI), measured by multiple breath washout, as a means to track disease progression in preschool children with CF.

METHODS

Children with CF between the ages of 2.5 and 6 years with a confirmed diagnosis of CF and age-matched healthy control subjects were enrolled at three North American CF centers. Multiple breath washout tests were performed at baseline, 1, 3, 6, and 12 months to mimic time points chosen in clinical care and interventional trials; spirometry was also conducted. A generalized linear mixed-effects model was used to distinguish LCI changes associated with normal growth and development (i.e., healthy children) from the progression of CF lung disease.

MEASUREMENTS AND MAIN RESULTS

Data were collected on 156 participants with 800 LCI measurements. Although both LCI and spirometry discriminated health from disease, only the LCI identified significant deterioration of lung function in CF over time. The LCI worsened during cough episodes and pulmonary exacerbations, whereas similar symptoms in healthy children were not associated with increased LCI values.

CONCLUSIONS

LCI is a useful marker to track early disease progression and may serve as a tool to guide therapies in young patients with CF.

Early Lung Disease in Infants and Preschool Children with Cystic Fibrosis. What Have We Learned and What Should We Do about It?

The past decade has seen significant advances in understanding of the pathogenesis and progression of lung disease in cystic fibrosis (CF). Pulmonary inflammation, infection, and structural lung damage manifest very early in life and are prevalent among preschool children and infants, often in the absence of symptoms or signs. Early childhood represents a pivotal period amenable to intervention strategies that could delay or prevent the onset of lung damage and alter the longer-term clinical trajectory for individuals with CF. This review summarizes what we have learned about early lung disease in children with CF and discusses the implications for future clinical practice and research.

Airway Microbiota in Bronchoalveolar Lavage Fluid from Clinically Well Infants with Cystic Fibrosis

Background

Upper airway cultures guide the identification and treatment of lung pathogens in infants with cystic fibrosis (CF); however, this may not fully reflect the spectrum of bacteria present in the lower airway. Our objectives were to characterize the airway microbiota using bronchoalveolar lavage fluid (BALF) from asymptomatic CF infants during the first year of life and to investigate the relationship between BALF microbiota, standard culture and clinical characteristics.

Methods

BALF, nasopharyngeal (NP) culture and infant pulmonary function testing data were collected at 6 months and one year of age during periods of clinical stability from infants diagnosed with CF by newborn screening. BALF was analyzed for total bacterial load by qPCR and for bacterial community composition by 16S ribosomal RNA sequencing. Clinical characteristics and standard BALF and NP culture results were recorded over five years of longitudinal follow-up.

Results

12 BALF samples were collected from 8 infants with CF. Streptococcus, Burkholderia, Prevotella, Haemophilus, Porphyromonas, and Veillonella had the highest median relative abundance in infant CF BALF. Two of the 3 infants with repeat BALF had changes in their microbial communities over six months (Morisita-Horn diversity index 0.36, 0.38). Although there was excellent percent agreement between standard NP and BALF cultures, these techniques did not routinely detect all bacteria identified by sequencing.

Conclusions

BALF in asymptomatic CF infants contains complex microbiota, often missed by traditional culture of airway secretions. Anaerobic bacteria are commonly found in the lower airways of CF infants.

The Impact of Secondhand Smoke Exposure on Children with Cystic Fibrosis: A Review

Secondhand smoke exposure (SHSe) has multiple adverse effects on lung function and growth, nutrition, and immune function in children; it is increasingly being recognized as an important modifier of disease severity for children with chronic diseases such as cystic fibrosis (CF). This review examines what is known regarding the prevalence of SHSe in CF, with the majority of reviewed studies utilizing parental-reporting of SHSe without an objective biomarker of exposure. A wide range of SHSe is reported in children with CF, but under-reporting is common in studies involving both reported and measured SHSe. Additionally, the impact of SHSe on respiratory and nutritional health is discussed, with potential decreases in long-term lung function, linear growth, and weight gain noted in CF children with SHSe. Immunologic function in children with CF and SHSe remains unknown. The impact of SHSe on cystic fibrosis transmembrane conductance regulator (CFTR) function is also examined, as reduced CFTR function may be a pathophysiologic consequence of SHSe in CF and could modulate therapeutic interventions. Finally, potential interventions for ongoing SHSe are delineated along with recommended future areas of study.

Early Childhood Risk Factors for Decreased FEV1 at Age Six to Seven Years in Young Children with Cystic Fibrosis

RATIONALE

There are limited objective measures of the severity of lung disease before children are able to routinely perform spirometry, generally at age 6 years. Identifying risk factors for reduced lung function at age 6 provides opportunities to intervene and slow the progression of cystic fibrosis (CF) lung disease.

OBJECTIVES

To evaluate early childhood predictors of lung function at age 6-7 in a large U.S. CF cohort in the current era of widespread early eradication therapy for Pseudomonas aeruginosa (P. aeruginosa).

METHODS

Participants were children with CF enrolled before age 4 in the Early Pseudomonas Infection Control (EPIC) Observational Study, a multicenter, longitudinal study that enrolled P. aeruginosa-negative children not exceeding 12 years of age. Linear regression was used to estimate the association between potential early childhood risk factors and the best FEV1% predicted at age 6-7 years.

MEASUREMENTS AND MAIN RESULTS

Four hundred and eighty-four children (of 1,797 enrolled in the EPIC Observational Study) met the eligibility criteria for this analysis. Mean (SD) age at enrollment was 2.0 (1.3) years. In a multivariable model adjusted for age at enrollment, the following risk factors were significantly associated with lower mean (95% confidence interval) FEV1% predicted at age 6-7: weight percentile less than 10% during the year of enrollment (-5.3 [-9.1, -1.5]), P. aeruginosa positive during the year of enrollment (-2.8 [-5.7, 0.0]), crackles or wheeze during the year of enrollment (-5.7 [-9.4, -1.9]), mother's education of high school or less (-4.2 [-7.3, -1.2]), and mother smoked during pregnancy (-4.4 [-8.8, 0.1]).

CONCLUSIONS

In this large U.S. cohort, we identified several early childhood risk factors for lower FEV1 at age 6-7 years, most of which are modifiable. Clinical trial registered with www.clinicaltrials.gov (NCT00097773).

Progressive ventilation inhomogeneity in infants with cystic fibrosis after pulmonary infection

Measures of ventilation distribution are promising for monitoring early lung disease in cystic fibrosis (CF). This study describes the cross-sectional and longitudinal impacts of pulmonary inflammation and infection on ventilation homogeneity in infants with CF.Infants diagnosed with CF underwent multiple breath washout (MBW) testing and bronchoalveolar lavage at three time points during the first 2 years of life.Measures were obtained for 108 infants on 156 occasions. Infants with a significant pulmonary infection at the time of MBW showed increases in lung clearance index (LCI) of 0.400 units (95% CI 0.150-0.648; p=0.002). The impact was long lasting, with previous pulmonary infection leading to increased ventilation inhomogeneity over time compared to those who remained free of infection (p<0.05). Infection with Haemophilus influenzae was particularly detrimental to the longitudinal lung function in young children with CF where LCI was increased by 1.069 units for each year of life (95% CI 0.484-1.612; p<0.001).Pulmonary infection during the first year of life is detrimental to later lung function. Therefore, strategies aimed at prevention, surveillance and eradication of pulmonary pathogens are paramount to preserve lung function in infants with CF.

Cystic fibrosis

Cystic fibrosis is an autosomal recessive, monogenetic disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The gene defect was first described 25 years ago and much progress has been made since then in our understanding of how CFTR mutations cause disease and how this can be addressed therapeutically. CFTR is a transmembrane protein that transports ions across the surface of epithelial cells. CFTR dysfunction affects many organs; however, lung disease is responsible for the vast majority of morbidity and mortality in patients with cystic fibrosis. Prenatal diagnostics, newborn screening and new treatment algorithms are changing the incidence and the prevalence of the disease. Until recently, the standard of care in cystic fibrosis treatment focused on preventing and treating complications of the disease; now, novel treatment strategies directly targeting the ion channel abnormality are becoming available and it will be important to evaluate how these treatments affect disease progression and the quality of life of patients. In this Primer, we summarize the current knowledge, and provide an outlook on how cystic fibrosis clinical care and research will be affected by new knowledge and therapeutic options in the near future. For an illustrated summary of this Primer, visit: http://go.nature.com/4VrefN.

A 3D machine vision method for non-invasive assessment of respiratory function

BACKGROUND

Respiratory function testing is important for detecting and monitoring illness, however, it is difficult for some patients, such as the young and severely ill, to perform conventional tests that require cooperation and/or patient contact.

METHOD

A new method was developed for non-contact breathing measurement, employing photometric stereo to capture the surface topography of the torso of an unconstrained subject. The surface is integrated to calculate time-dependent volume changes during respiration.

RESULTS

The method provides a useful means of continuously measuring volume changes during respiration with high spatial and temporal resolution. The system was tested by comparison with pneumotachometry equipment and a clear periodic signal, of a frequency corresponding to the reference data, was observed.

CONCLUSION

The approach is unique in performing breathing monitoring (with potential diagnostic capability) for unconstrained patients in virtually any lighting conditions (including darkness during sleep) and in a non-contact, unobtrusive (i.e. using imperceptible light) fashion. Copyright © 2015 John Wiley & Sons, Ltd.

The findings of a clinical surveillance bronchoalveolar lavage programme in pre-school patients with cystic fibrosis

BACKGROUND

Evidence suggests infection is present in the lower airways of young children with cystic fibrosis (CF), even when clinically stable. Oropharyngeal samples (OPS) are typically used for airway surveillance in these children but have been shown to have low positive predictive values and low sensitivity in detecting lower airway infection when compared with the reference standard, bronchoalveolar lavage (BAL).

METHODS

The aim of this study was to determine the prevalence of pathogens in lower airway samples detected as part of a pilot clinical BAL surveillance programme, in young children aged from one to six years old, and to ascertain if their detection resulted in a change in treatment.

RESULTS

During the study 78 bronchoscopies were performed on 38 patients. The average age at the time of bronchoscopy was 2.7 years (range 0.3-7.0 year). A significant organism was detected in 58 (74.5%) BALs. Haemophilus influenzae was detected in 27 (34.6%) samples, 16 (20.5%) samples had Staphylococcus aureus, and nine (11.5%) had Pseudomonas aeruginosa. Change in treatment occurred after 46 (58.9%) BALs.

CONCLUSIONS

This study suggests that, in young non-expectorating children with CF, routine surveillance bronchoscopy allows the detection of significant lower airway pathogens and provides the opportunity for targeted treatment of sub-clinical infection.

Novel outcome measures for clinical trials in cystic fibrosis

Cystic fibrosis (CF) is a common inherited condition caused by mutations in the gene encoding the CF transmembrane regulator protein. With increased understanding of the molecular mechanisms underlying CF and the development of new therapies there comes the need to develop new outcome measures to assess the disease, its progression and response to treatment. As there are limitations to the current endpoints accepted for regulatory purposes, a workshop to discuss novel endpoints for clinical trials in CF was held in Anaheim, California in November 2011. The pros and cons of novel outcome measures with potential utility for evaluation of novel treatments in CF were critically evaluated. The highlights of the 2011 workshop and subsequent advances in technologies and techniques that could be used to inform the development of clinical trial endpoints are summarized in this review. Pediatr Pulmonol. © 2014 The Authors. Pediatric Pulmonology published by Wiley Periodicals, Inc.

Cystic fibrosis: NHLBI Workshop on the Primary Prevention of Chronic Lung Diseases

Cystic fibrosis (CF) is a life-limiting, monogenic disorder characterized by chronic sinopulmonary and gastrointestinal involvement. Progressive pulmonary disease leads to death in the majority of patients. Despite its well-defined molecular basis related to defects in the cystic fibrosis transmembrane conductance regulator anion transport channel, there are large gaps in our understanding of the origin of CF lung disease. Disease has been shown to be present in infancy, and there is mounting evidence that abnormalities begin in utero. Heterogeneity of clinical presentations and severity suggest that many factors involved in lung disease have yet to be fully elucidated. Although new advances in therapeutic treatments have shown promise in delaying disease progression, the prevention of pulmonary disease at its origin (primary prevention) should be a key goal of CF care. The objective of this workshop was to (1) review our understanding of the origins of CF lung disease, (2) determine gaps in the knowledge base that are most significant and most likely to enable prevention of CF lung disease, and (3) prioritize new research questions that will promote pulmonary health in both CF and other childhood lung diseases. The goal of this report is to provide recommendations for future research that will improve our understanding of pulmonary development in health and disease, improve outcome measures and biomarkers for early lung disease, and determine therapeutic targets and strategies to prevent the development of lung disease in children with CF.

Lung function in African infants: a pilot study

BACKGROUND

The burden of childhood respiratory illness is large in low and middle income countries (LMICs). Infant lung function (ILF) testing may provide useful information about lung growth and susceptibility to respiratory disease. However, ILF has not been widely available in LMICs settings where the greatest burden of childhood respiratory disease occurs.

AIM

To implement and evaluate a pilot study of ILF testing in a semi-rural setting in South Africa.

METHOD

Infant lung function testing was established at a community hospital in South Africa. All measures were done in unsedated infants during sleep. Measurements, made with the infant quietly breathing through a face mask and bacterial filter, included tidal breathing (TBFVL), exhaled nitric oxide (eNO), and sulphur hexafluoride multiple breath washout (MBW) measures using an ultrasonic flow meter and chemoluminescent NO analyzer.

RESULTS

Twenty infants, mean age of 7.7 (SD 2.9) weeks were tested; 8 (40%) were Black African and 12 (60%) were mixed race. Five (25%) infants were preterm. There were 19 (95%) successful TBFVL and NO tests and 18 (90%) successful MBW tests. The mean tidal volume was 30.5 ml (SD 5.9), respiratory rate 50.2 breaths per minute (SD 8.7), and eNO 10.4 ppb (SD 7.3). The mean MBW measures were: functional residual capacity 71 ml (SD 13) and the lung clearance index 7.6 (SD 0.5). The intra-subject coefficient of variations (CV) of lung function measures were similar to published normative data for Caucasian European infants.

CONCLUSION

In this study we demonstrate that unsedated infant lung function measures of tidal breathing, MBW, and eNO are feasible in a semi-rural African setting with rates comparable to those reported from high income countries.

Detrimental effects of secondhand smoke exposure on infants with cystic fibrosis

RATIONALE

Secondhand smoke (SHS) has deleterious respiratory, immune, and nutritional effects in children, but there is little data regarding the effects of SHS exposure in infants with cystic fibrosis (CF).

METHODS

A retrospective chart review was undertaken from 2008 to 2012 of 75 infants with CF. Growth, lung function, Chest CT imaging, and microbiologic characteristics were compared between 4 and 12 months for SHS and non-SHS exposed patients.

RESULTS

SHS exposed infants with CF had decreased growth between 4 and 12 months compared to non-SHS exposed infants. SHS exposure was associated with increased bronchodilator responsiveness and air trapping, but no other lung function or radiologic differences. SHS exposure was also associated with increased methicillin resistant Staphylococcus aureus (MRSA) and anaerobic growth on respiratory culture. There was no difference in Pseudomonas aeruginosa between groups. There were no differences in antibiotic use or hospitalizations between the groups.

CONCLUSIONS

SHS exposure in CF infants is associated with diminished growth, increased air trapping and bronchodilator responsiveness, and propensity to culture MRSA and facultative anaerobic bacteria, suggesting the need for early, aggressive parental smoking cessation interventions to prevent SHS exposure complications.

The Respiratory System

This chapter addresses upper airway physiology for the pediatric intensivist, focusing on functions that affect ventilation, with an emphasis on laryngeal physiology and control in breathing. Effective control of breathing ensures that the airway is protected, maintains volume homeostasis, and provides ventilation. Upper airway structures are effectors for all of these functions that affect the entire airway. Nasal functions include air conditioning and protective reflexes that can be exaggerated and involve circulatory changes. Oral cavity and pharyngeal patency enable airflow and feeding, but during sleep pharyngeal closure can result in apnea. Coordination of breathing with sucking and nutritive swallowing alters during development, while nonnutritive swallowing at all ages limits aspiration. Laryngeal functions in breathing include protection of the subglottic airway, active maintenance of its absolute volume, and control of tidal flow patterns. These are vital functions for normal lung growth in fetal life and during rapid adaptations to breathing challenges from birth through adulthood. Active central control of breathing focuses on the coordination of laryngeal and diaphragmatic activities, which adapts according to the integration of central and peripheral inputs. For the intensivist, knowledge of upper airway physiology can be applied to improve respiratory support. In a second part the mechanical properties of the respiratory system as a critical component of the chain of events that result in translation of the output of the respiratory rhythm generator to ventilation are described. A comprehensive understanding of respiratory mechanics is essential to the delivery of optimized and individualized mechanical ventilation. The basic elements of respiratory mechanics will be described and developmental changes in the airways, lungs, and chest wall that impact on measurement of respiratory mechanics with advancing postnatal age are reviewed. This will be follwowed by two sections, the first on respiratory mechanics in various neonatal pathologies and the second in pediatric pathologies. The latter can be classified in three categories. First, restrictive diseases may be of pulmonary origin, such as chronic interstitial lung diseases or acute lung injury/acute respiratory distress syndrome, which are usually associated with reduced lung compliance. Restrictive diseases may also be due to chest wall abnormalities such as obesity or scoliosis (idiopathic or secondary to neuromuscular diseases), which are associated with a reduction in chest wall compliance. Second, obstructive diseases are represented by asthma and wheezing disorders, cystic fibrosis, long term sequelae of neonatal lung disease and bronchiolitis obliterans following hematopoietic stem cell transplantation. Obstructive diseases are defined by a reduced FEV1/VC ratio. Third, neuromuscular diseases, mainly represented by DMD and SMA, are associated with a decrease in vital capacity linked to respiratory muscle weakness that is better detected by PImax, PEmax and SNIP measurements.

Interpretation of lung function in infants and young children with cystic fibrosis

The last decade has seen a significant advance in understanding about early lung disease in cystic fibrosis (CF). As studies that have measured lung function in preschool years are conducted in association with surveillance of infection, inflammation and early structural changes, and emerging longitudinal data become available, a better insight into the very early onset and nature of such lung disease is emerging. Interventions during the preschool years are increasingly viewed as being crucial to delaying and minimizing disease progression as this is the most important period of postnatal life in terms of lung development and airway remodelling. Lung function measurement in CF is potentially an important assessment tool and is used in routine clinical practice in several centres already. Results of studies from lung function tests that, on the basis of their underpinning physiology, are viewed as being best suited currently for the early detection of lung disease in CF are reviewed.

Air trapping and airflow obstruction in newborn cystic fibrosis piglets

RATIONALE

Air trapping and airflow obstruction are being increasingly identified in infants with cystic fibrosis. These findings are commonly attributed to airway infection, inflammation, and mucus buildup.

OBJECTIVES

To learn if air trapping and airflow obstruction are present before the onset of airway infection and inflammation in cystic fibrosis.

METHODS

On the day they are born, piglets with cystic fibrosis lack airway infection and inflammation. Therefore, we used newborn wild-type piglets and piglets with cystic fibrosis to assess air trapping, airway size, and lung volume with inspiratory and expiratory X-ray computed tomography scans. Micro-computed tomography scanning was used to assess more distal airway sizes. Airway resistance was determined with a mechanical ventilator. Mean linear intercept and alveolar surface area were determined using stereologic methods.

MEASUREMENTS AND MAIN RESULTS

On the day they were born, piglets with cystic fibrosis exhibited air trapping more frequently than wild-type piglets (75% vs. 12.5%, respectively). Moreover, newborn piglets with cystic fibrosis had increased airway resistance that was accompanied by luminal size reduction in the trachea, mainstem bronchi, and proximal airways. In contrast, mean linear intercept length, alveolar surface area, and lung volume were similar between both genotypes.

CONCLUSIONS

The presence of air trapping, airflow obstruction, and airway size reduction in newborn piglets with cystic fibrosis before the onset of airway infection, inflammation, and mucus accumulation indicates that cystic fibrosis impacts airway development. Our findings suggest that early airflow obstruction and air trapping in infants with cystic fibrosis might, in part, be caused by congenital airway abnormalities.

Lung clearance index as an outcome measure for clinical trials in young children with cystic fibrosis. A pilot study using inhaled hypertonic saline

RATIONALE

Lung clearance index (LCI), measured by multiple breath washout (MBW), is a noninvasive measure of ventilation inhomogeneity that holds promise as an objective physiologic endpoint for clinical trials in infants and preschool children with cystic fibrosis (CF).

OBJECTIVES

To study the feasibility of using LCI to assess treatment effect outcomes in CF trials of infants and preschoolers.

METHODS

The Infant Study of Inhaled Saline trial was a multicenter, randomized, controlled trial of hypertonic (7%) versus isotonic (0.9%) saline inhaled twice daily for 48 weeks in children with CF under 6 years of age. LCI measurements were performed in a single-center pilot substudy at baseline and 48 weeks using a respiratory mass spectrometer and sulfur hexafluoride as the tracer gas. LCI measurements were standardized using published normative data (zLCI) to account for height-related changes in LCI during early childhood. A generalized estimating equation model with an interaction between treatment group and test occasion was used to estimate a treatment effect.

MEASUREMENTS AND MAIN RESULTS

A total of 27 participants were randomized; 25 participants, aged (median [range]) 2.6 (0.34-4.95) years, had acceptable baseline and follow-up LCI measures. On average, LCI decreased in the hypertonic saline group (n = 12) by 1.19 z-scores units (95% confidence interval [CI] = -2.46 to 0.06), and remained stable in the isotonic saline group (n = 13) at 0.81 (95% CI = -0.40 to 2.02). A significant treatment effect was observed for zLCI (2.01; 95% CI = 0.26 to 3.76; P = 0.025).

CONCLUSIONS

MBW testing is feasible in an interventional study in infants and preschool children with CF. These pilot findings support the development of MBW and LCI as an objective outcome measure in interventional trials in young children with CF, and provide estimates for sample size calculations for future studies.

Evolution of lung function during the first year of life in newborn screened cystic fibrosis infants

Rationale

Newborn screening (NBS) for cystic fibrosis (CF) allows early intervention. Design of randomised controlled trials (RCT) is currently impeded by uncertainty regarding evolution of lung function, an important trial end point in such infants.

Objective

To assess changes in pulmonary function during the first year of life in CF NBS infants.

Methods

Observational longitudinal study. CF NBS infants and healthy controls were recruited between 2009 and 2011. Lung Clearance Index (LCI), plethysmographic lung volume (plethysmographic functional residual capacity (FRC_pleth)) and forced expired volume (FEV_0.5) were measured at 3 months and 1 year of age.

Main results

Paired measurements were obtained from 72 CF infants and 44 controls. At 3 months, CF infants had significantly worse lung function for all tests. FEV_0.5 improved significantly (0.59 (95% CI 0.18 to 0.99) z-scores; p<0.01) in CF infants between 3 months and 1 year, and by 1 year, FEV_0.5 was only 0.52 (0.89 to 0.15) z-scores less than in controls. LCI and FRC_pleth remained stable throughout the first year of life, being on average 0.8 z-scores higher in infants with CF. Pulmonary function at 1 year was predicted by that at 3 months. Among the 45 CF infants with entirely normal LCI and FEV_0.5 at 3 months, 80% remained so at 1 year, while 74% of those with early abnormalities remained abnormal at 1 year.

Conclusions

This is the first study reporting improvements in FEV_0.5 over time in stable NBS CF infants treated with standard therapy. Milder changes in lung function occurred by 1 year than previously reported. Lung function at 3 months predicts a high-risk group, who should be considered for intensification of treatment and enrolment into RCTs.

Cystic fibrosis in the era of genomic medicine

PURPOSE OF REVIEW

The field of cystic fibrosis (CF) is changing dramatically as the scientific knowledge accumulated since the cloning of the cystic fibrosis transmembrane conductance regulator (CFTR) gene is being translated into effective therapies to correct the basic defect and provide better disease models and in-depth understanding of the basic mechanisms of disease.

RECENT FINDINGS

This review focuses on three main aspects of the recent advances in the field: understanding the lung disease pathophysiology (in particular, the early events that condition its onset), better definition of the complex microbiology of the CF airway, and therapeutic developments. Although the most recently developed therapies, whether approved or under study, do not constitute a definitive cure, the benefit to patients is already becoming clearly apparent.

SUMMARY

As the field continues to change rapidly and new therapies are being identified, CF has become a paradigm for the application of concepts such as translational medicine, genomic medicine, and personalized care, with measurable clinical benefit for the patients affected by this disease.

Identification of SNPs in the cystic fibrosis interactome influencing pulmonary progression in cystic fibrosis

There is growing evidence that the great phenotypic variability in patients with cystic fibrosis (CF) not only depends on the genotype, but apart from a combination of environmental and stochastic factors predominantly also on modifier gene effects. It has been proposed that genes interacting with CF transmembrane conductance regulator (CFTR) and epithelial sodium channel (ENaC) are potential modifiers. Therefore, we assessed the impact of single-nucleotide polymorphisms (SNPs) of several of these interacters on CF disease outcome. SNPs that potentially alter gene function were genotyped in 95 well-characterized p.Phe508del homozygous CF patients. Linear mixed-effect model analysis was used to assess the relationship between sequence variants and the repeated measurements of lung function parameters. In total, we genotyped 72 SNPs in 10 genes. Twenty-five SNPs were used for statistical analysis, where we found strong associations for one SNP in PPP2R4 with the lung clearance index (P ≤ 0.01), the specific effective airway resistance (P ≤ 0.005) and the forced expiratory volume in 1 s (P ≤ 0.005). In addition, we identified one SNP in SNAP23 to be significantly associated with three lung function parameters as well as one SNP in PPP2R1A and three in KRT19 to show a significant influence on one lung function parameter each. Our findings indicate that direct interacters with CFTR, such as SNAP23, PPP2R4 and PPP2R1A, may modify the residual function of p.Phe508del-CFTR while variants in KRT19 may modulate the amount of p.Phe508del-CFTR at the apical membrane and consequently modify CF disease.

Improvement in pulmonary function following antibiotics in infants with cystic fibrosis

BACKGROUND

Recent studies have shown the presence of lung disease in even asymptomatic infants with cystic fibrosis (CF). While pulmonary function testing (PFT) is often used to follow progression of lung disease and guide treatment in older children with CF, little data is available on change in infant PFTs in young children with CF.

OBJECTIVE

To determine change in infant PFTs before and after antibiotic therapy for pulmonary exacerbation in infants with CF.

METHODS

Retrospective cohort study of infants with CF who underwent clinically indicated infant PFTs before and after antibiotic therapy for CF pulmonary exacerbation at the University of North Carolina at Chapel Hill.

RESULTS

Pre- and post-antibiotics PFT data was available on 11 infants with CF, with a mean age of 102 weeks at time of first PFT. The majority of infants were symptomatic prior to antibiotics, and showed statistically significant improvement in clinical parameters following treatment. Prior to antibiotics, PFTs showed evidence of substantial obstructive disease (mean z-scores for FVC, FEV(0.5) , and FEF(25-75) of -1.81, -3.06, and -4.5, respectively) and air-trapping/hyperinflation (mean z-scores for FRCpleth, RV, and RV/TLC of 8.86, 7.1, and 3.31, respectively). Following antibiotics, all of the above parameters showed statistically significant improvement.

DISCUSSION

We have shown a statistically significant improvement in infant PFT measures following antibiotic therapy in a cohort of 11 infants with CF, which paralleled improvement in clinical parameters. Though infant PFTs showed improvement, they remained abnormal in the majority of subjects, with persistent air-trapping and hyperinflation after antibiotic therapy. Our findings suggest that infant PFTs are sensitive to acute clinical changes in children with CF, and may be a useful tool in managing infants with CF.

Lung clearance index at 4 years predicts subsequent lung function in children with cystic fibrosis

RATIONALE

The markedly improved life expectancy of children with cystic fibrosis (CF) has created a new challenge, as traditional markers of lung disease are frequently normal in young children. This prevents identification of individuals who may benefit from more aggressive therapy and also obliges large study numbers and prolonged duration for intervention studies. There is an urgent need for alternative surrogates that detect early lung disease and track through early childhood.

OBJECTIVES

This study aimed to determine whether multiple-breath washout (MBW) results at preschool age can predict subsequent abnormal lung function.

METHODS

Preschool children (3-5 yr) with CF and healthy control subjects underwent spirometry and MBW with testing repeated during early school age (6-10 yr). Primary outcomes were FEV1 from spirometry and lung clearance index (LCI) from MBW.

MEASUREMENTS AND MAIN RESULTS

Forty-eight children with CF and 45 healthy children completed testing. Thirty-five (73%) children with CF had abnormal LCI at preschool age, whereas only five had abnormal FEV1. The positive predictive value of preschool LCI for predicting any abnormal school-age result was 94%, with a negative predictive value of 62%. Only one child with abnormal FEV1 at school age had had a normal preschool LCI. In contrast, for preschool FEV1 the positive predictive value was 100%, but negative predictive value was only 25%.

CONCLUSIONS

This study demonstrates that an abnormal preschool LCI predicts subsequent lung function abnormalities, whereas a normal preschool LCI usually remains normal. MBW has potential as a clinical and research outcome in young children with CF.

Multicenter evaluation of infant lung function tests as cystic fibrosis clinical trial endpoints

RATIONALE

The conducting of clinical trials in infants with cystic fibrosis (CF) has been hindered by lack of sensitive outcome measures.

OBJECTIVES

To evaluate safety, feasibility, and ability to detect abnormalities in lung function of serial pulmonary function tests (PFTs) in infants with CF.

METHODS

Multicenter observational study using a commercial device, rigorous training, ongoing quality control, and over-reading of data by an independent panel. Raised volume rapid thoracoabdominal compression technique and plethysmography were performed at enrollment and at 6 and 12 months, with an additional 1-month reproducibility visit.

MEASUREMENTS AND MAIN RESULTS

A total of 342 procedures were performed in 100 infants with CF at 10 centers. FRC measurements were acceptable at a higher proportion of study visits (89%) than raised volume (72%) or fractional lung volume (68%) measurements. Average Z scores for many parameters differed significantly from historical control values. Mean (95% confidence interval) Z scores were: -0.52 (-0.78 to -0.25) for forced expiratory flow at 75% (FEF₇₅) for FVC; 1.92 (1.39-2.45) for FRC; 1.22 (0.68-1.76) for residual volume; 0.87 (0.60-1.13) for FRC/total lung capacity; and 0.66 (0.27-1.06) for residual volume/total lung capacity. For future multicenter clinical trials using infant PFTs as primary endpoints, minimum detectable treatment effects are presented for several sample sizes.

CONCLUSIONS

In this 10-center study, key PFT measures were significantly different in infants with CF than in historical control subjects. However, infant PFTs do not yet appear ready as primary efficacy endpoints for multicenter clinical trials, particularly at inexperienced sites, based on acceptability rates, variability, and potentially large sample sizes required to detect reasonable treatment effects.

Early bronchiectasis in cystic fibrosis detected by surveillance CT

There is emerging evidence that cystic fibrosis lung disease begins early in infancy. Newborn screening allows early detection and surveillance of pulmonary disease and the possibility of early intervention in this life-shortening condition. We report two children with cystic fibrosis who underwent a comprehensive assessment from diagnosis that included measurement of lung function, limited-slice high-resolution CT and BAL performed annually. Early aggressive surveillance enabled significant lung disease and bronchiectasis to be detected during the first few years of life and led to a change in management, highlighting a clinical role for CT scanning during the preschool years in children with cystic fibrosis.

Cystic Fibrosis Foundation evidence-based guidelines for management of infants with cystic fibrosis

Newborn screening for cystic fibrosis (CF) offers the opportunity for early medical and nutritional intervention that can lead to improved outcomes. Management of the asymptomatic infant diagnosed with CF through newborn screening, prenatal diagnosis, or sibling screening is different from treatment of the symptomatically diagnosed individual. The focus of management is on maintaining health by preventing nutritional and respiratory complications. The CF Foundation convened a committee to develop recommendations based on a systematic review of the evidence and expert opinion. These guidelines encompass monitoring and treatment recommendations for infants diagnosed with CF and are intended to help guide families, primary care providers, and specialty care centers in the care of infants with CF.

Long-term gas exchange characteristics as markers of deterioration in patients with cystic fibrosis

Background and Aim

In patients with cystic fibrosis (CF) the architecture of the developing lungs and the ventilation of lung units are progressively affected, influencing intrapulmonary gas mixing and gas exchange. We examined the long-term course of blood gas measurements in relation to characteristics of lung function and the influence of different CFTR genotype upon this process.

Methods

Serial annual measurements of PaO₂ and PaCO₂ assessed in relation to lung function, providing functional residual capacity (FRC_pleth), lung clearance index (LCI), trapped gas (V_TG), airway resistance (sR_eff), and forced expiratory indices (FEV₁, FEF₅₀), were collected in 178 children (88 males; 90 females) with CF, over an age range of 5 to 18 years. Linear mixed model analysis and binary logistic regression analysis were used to define predominant lung function parameters influencing oxygenation and carbon dioxide elimination.

Results

PaO₂ decreased linearly from age 5 to 18 years, and was mainly associated with FRC_pleth, (p < 0.0001), FEV₁ (p < 0.001), FEF₅₀ (p < 0.002), and LCI (p < 0.002), indicating that oxygenation was associated with the degree of pulmonary hyperinflation, ventilation inhomogeneities and impeded airway function. PaCO₂ showed a transitory phase of low PaCO₂ values, mainly during the age range of 5 to 12 years. Both PaO₂ and PaCO₂ presented with different progression slopes within specific CFTR genotypes.

Conclusion

In the long-term evaluation of gas exchange characteristics, an association with different lung function patterns was found and was closely related to specific genotypes. Early examination of blood gases may reveal hypocarbia, presumably reflecting compensatory mechanisms to improve oxygenation.

Sputum desmosine during hospital admission for pulmonary exacerbation in cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) lung disease is characterized by structural changes in the airways and parenchyma. No sputum biomarker exists to measure the degree of active structural destruction during pulmonary exacerbation in patients with CF. The noninvasive measurement of desmosine, a breakdown product of elastin, may reflect ongoing lung injury and serve as a biomarker of short-term damage. Our objectives were to measure desmosine in the sputum of patients with CF hospitalized for treatment of a pulmonary exacerbation and to explore the correlation between desmosine levels and other markers of clinical improvement, including lung function and inflammatory mediators, following hospitalization.

METHODS

Sputum and blood samples collected and lung function measurements were made at multiple time points during hospitalization. We used a repeated measures model, adjusted for age and time between measurements, to compare log-transformed sputum desmosine levels across multiple time points and to correlate those levels with related variables.

RESULTS

Desmosine levels were measured by radioimmunoassay in 71 expectorated sputum samples from 19 patients with CF hospitalized for 26 pulmonary exacerbations (range of results, 0 to 200 pmol/L desmosine/mL). Sputum desmosine levels decreased significantly during the first week of hospitalization (p = 0.04). Desmosine levels were positively associated with plasma C-reactive protein (rho = 0.59; p = 0.03), sputum interleukin-8 (rho = 0.86; p < 0.01), and sputum neutrophil elastase (rho = 0.78; p < 0.01).

CONCLUSIONS

Sputum desmosine, a novel measure of acute structural lung injury, may serve as a marker of structural lung damage occurring during exacerbations of lung disease in CF.

Association of lower airway inflammation with physiologic findings in young children with cystic fibrosis

BACKGROUND

The relationship between lower airway markers of inflammation and infection with physiologic findings is poorly understood in young children with cystic fibrosis (CF). The goal of this study was to evaluate the association of bronchoalveolar lavage fluid (BALF) markers of infection and inflammation, including mediators linked to airway remodeling, to infant lung function values in young children with CF undergoing clinically indicated bronchoscopy.

METHODS

Plethysmography and the raised volume rapid thoracoabdominal compression (RVRTC) technique were performed in 16 sedated infants and young children with CF prior to bronchoscopy. BALF was collected and analyzed for pathogen density, cell count, % neutrophils, transforming growth factor beta 1 (TGF-beta(1)), matrix metalloproteinases (MMP), and interleukin-8 (IL-8).

RESULTS

There was a significant direct correlation between functional residual capacity (FRC), the ratio of residual volume to total lung capacity (RV/TLC) and FRC/TLC with % neutrophils (P < 0.05). Forced expiratory flows were inversely correlated to % neutrophils (P < 0.01). Lung function parameters did not differentiate those with and without lower airway infection; however, pathogen density directly correlated with FRC and inversely correlated with flows (P < 0.05). In a subset of the population, MMP-2 directly correlated with RV/TLC and inversely correlated with flows (P < 0.05) and TGF-beta(1) directly correlated with FRC (P < 0.05).

CONCLUSIONS

Results from this study suggest that lower airway inflammation as well as mediators linked to airway remodeling play an active role in pulmonary deterioration in CF infants and young children undergoing clinically indicated bronchoscopy.