Putting lung function and physiology into perspective: cystic fibrosis in adults

Home Based Rehabilitation in Children and Adolescents with Cystic Fibrosis: A Systematic Review with Meta-Analysis and Grade Recommendations

OBJECTIVE

The objective of this study is to elucidate the effectiveness of home based rehabilitation (HBR) and compare its results with those obtained in conventional rehabilitation (CR) programs, carried out in clinics and/or outpatient clinics.

METHODS

Searches were conducted in five databases of randomized clinical trials. Study selection, data extraction, and assessment of the methodological quality of included studies were conducted independently by two reviewers, with discrepancies resolved by a third reviewer.

RESULTS

The results demonstrate post-intervention values favorable to the use of HBR when compared to control group in the outcomes of forced expiratory volume in 1 second (FEV1) (MD = 14% CI: 5.42 to 22.58, p = 0.001), forced vital capacity (FVC) (MD = 8.00% CI: 0.83 to 15.17, p = 0.03) and quality of life by the Cystic Fibrosis Questionnaire - revised in the categories (Child version score" (MD= 0.71%CI: 0.15 to 1.27, p = 0.01) and "Parent version score" (MD= 0.67%CI: 0.11 to 1.23, p = 0.02). Furthermore, we noticed an increase in the distance covered in the 6-minute walk test (MD= 34.75%CI: -8.00 to 77.50, p = 0.14), in favor of HBR.

CONCLUSIONS

We found that supervised or partially supervised HBR promotes improvements in FEV1, FVC and related quality of life in children and/or adolescents with cystic fibrosis.

Role of the Physical Therapist in Cystic Fibrosis Care

In looking back on 2020 and 2021, this Perspective reflects on the monumental impacts of the rollout of cystic fibrosis (CF) transmembrane conductance regulator highly effective modulator therapies and the COVID-19 pandemic on the management of CF. Advancements in the clinical management of people with CF have been both enormous and rapid, and physical therapists specializing in the care of people with CF have been at the forefront of driving this evolution in care. This year sees the 30th anniversary of the UK Association of Chartered Physiotherapists in Cystic Fibrosis and, as is inevitable in reaching such milestones, thoughts have turned to origins, role, impacts, and the future. With the changing demographics of the population of people with CF after the introduction of highly effective modulator therapies, potentially with fewer secondary complications, the future role of the physical therapist who specializes in CF is in question. This Perspective reflects on and highlights the role of physical therapy within CF and provides insights into how physical therapists and respiratory therapists can evolve their roles to ensure relevance for the future.

Respiratory Impedance is Associated with Ventilation and Diffusing Capacity in Patients with Idiopathic Pulmonary Fibrosis Combined with Emphysema

Purpose

Pulmonary fibrosis and emphysema result in relatively maintained ventilation and reduced diffusing capacity. This pulmonary functional impairment complicates the evaluation of pulmonary function in patients with combined pulmonary fibrosis and emphysema (CPFE). Therefore, a single and easy-to-use pulmonary function index to evaluate patients with CPFE warrants further studies. Respiratory impedance can easily be provided by oscillometry and might be a candidate index to evaluate pulmonary function in patients with CPFE. As a preliminary study to assess the utility of respiratory impedance, we investigated the associations of physiological indices, including respiratory impedance, in patients with idiopathic pulmonary fibrosis (IPF) with and without emphysema.

Patients and Methods

This retrospective study evaluated patients with IPF who did and did not satisfy the diagnostic criteria of CPFE. All patients underwent oscillometry, spirometry, and diffusing capacity for carbon monoxide (D_LCO). Correlations of the obtained physiological indices were analyzed.

Results

In total, 47 patients were included (18 and 29 patients with CPFE and IPF, respectively). Respiratory reactance (Xrs) at 5 Hz (X5) in the inspiratory phase was associated with forced vital capacity (FVC) % predicted in patients with CPFE (r_S=0.576, P=0.012) and IPF (r_S=0.539, P=0.003). Inspiratory X5 positively correlated with D_LCO % predicted only in patients CPFE (r_S=0.637, P=0.004).

Conclusion

Emphysema might associate Xrs with ventilation and diffusing capacity in patients with IPF and emphysema. Given the multiple correlations of Xrs with FVC and D_LCO, this study warrants further studies to verify the utility of oscillometry in a large-scale study for patients with CPFE.

Use of Dynamic Chest Radiography to Assess Treatment of Pulmonary Exacerbations in Cystic Fibrosis

Background Although spirometry is an important marker in the management of pulmonary exacerbations in cystic fibrosis (CF), it is a forced maneuver and can generate aerosol. Therefore, it may be difficult to perform in some individuals. Dynamic chest radiography (DCR) provides real-time information regarding pulmonary dynamics alongside fluoroscopic-style thoracic imaging. Purpose To assess the effect of pulmonary exacerbation treatment by using both spirometry and DCR and assess the clinical utility of DCR in participants with CF experiencing pulmonary exacerbations. Materials and Methods In this prospective, observational, single-center pilot study, spirometry and DCR were performed before and after treatment of pulmonary exacerbations in participants with CF between December 2019 and August 2020. Spirometry measured forced expiratory volume in 1 second (FEV₁) and forced vital capacity. DCR helped to measure projected lung area (PLA), hemidiaphragm midpoint position, and speed during tidal and deep breathing. Data were analyzed by using the paired t test or Wilcoxon signed-rank test. Correlation was assessed by using the Spearman rank correlation coefficient. Results Twenty participants with CF (mean age, 25 years ± 7 [standard deviation]; 14 women) were evaluated. Spirometry showed that percentage predicted FEV₁ improved from a median of 44% (interquartile range [IQR], 17%) before treatment to 55% (IQR, 16%) after treatment (P = .004). DCR showed improvement in median deep breathing excursion for left and right hemidiaphragms (from 18 [IQR, 11] to 25 [IQR, 16] mm [P = .03] and from 13 [IQR, 6] to 19 [IQR, 14] mm [P = .03], respectively) and in median expiratory speed following deep breathing for left and right hemidiaphragms (from 7 [IQR, 2] to 11 [IQR, 5] mm/sec [P = .004] and 6 [IQR, 3] to 9 [IQR, 6] mm/sec [P = .004], respectively). PLA rate of change during full expiration and change in PLA during tidal breathing improved (from a mean of 42 cm²/sec ± 16 to 56 cm²/sec ± 24 [P = .03] and from a mean of 29 cm² ± 14 to 35 cm² ± 10 [P = .03], respectively). Conclusion Dynamic chest radiography demonstrated improvement in diaphragm speed and range of chest wall movement during respiration aftere treatment for pulmonary exacerbations in cystic fibrosis and showed potential as a tool to investigate the effect of pulmonary exacerbations on lung mechanics. Clinical trials registration no. NCT01234567 Published under a CC BY 4.0 license. Online supplemental material is available for this article.

Management of respiratory tract exacerbations in people with cystic fibrosis: Focus on imaging

Respiratory tract exacerbations play a crucial role in progressive lung damage of people with cystic fibrosis, representing a major determinant in the loss of functional lung tissue, quality of life and patient survival. Detection and monitoring of respiratory tract exacerbations are challenging for clinicians, since under- and over-treatment convey several risks for the patient. Although various diagnostic and monitoring tools are available, their implementation is hampered by the current definition of respiratory tract exacerbation, which lacks objective "cut-offs" for clinical and lung function parameters. In particular, the latter shows a large variability, making the current 10% change in spirometry outcomes an unreliable threshold to detect exacerbation. Moreover, spirometry cannot be reliably performed in preschool children and new emerging tools, such as the forced oscillation technique, are still complementary and need more validation. Therefore, lung imaging is a key in providing respiratory tract exacerbation-related structural and functional information. However, imaging encompasses several diagnostic options, each with different advantages and limitations; for instance, conventional chest radiography, the most used radiological technique, may lack sensitivity and specificity in respiratory tract exacerbations diagnosis. Other methods, including computed tomography, positron emission tomography and magnetic resonance imaging, are limited by either radiation safety issues or the need for anesthesia in uncooperative patients. Finally, lung ultrasound has been proposed as a safe bedside option but it is highly operator-dependent and there is no strong evidence of its possible use during respiratory tract exacerbation. This review summarizes the clinical challenges of respiratory tract exacerbations in patients with cystic fibrosis with a special focus on imaging. Firstly, the definition of respiratory tract exacerbation is examined, while diagnostic and monitoring tools are briefly described to set the scene. This is followed by advantages and disadvantages of each imaging technique, concluding with a diagnostic imaging algorithm for disease monitoring during respiratory tract exacerbation in the cystic fibrosis patient.

Exploring the 175-year history of spirometry and the vital lessons it can teach us today

175 years have elapsed since John Hutchinson introduced the world to his version of an apparatus that had been in development for nearly two centuries, the spirometer. Though he was not the first to build a device that sought to measure breathing and quantify the impact of disease and occupation on lung function, Hutchison coined the terms spirometer and vital capacity that are still in use today, securing his place in medical history. As Hutchinson envisioned, spirometry would become crucial to our growing knowledge of respiratory pathophysiology, from Tiffeneau and Pinelli's work on forced expiratory volumes, to Fry and Hyatt's description of the flow-volume curve. In the 20th century, standardization of spirometry further broadened its reach and prognostic potential. Today, spirometry is recognized as essential to respiratory disease diagnosis, management and research. However, controversy exists in some of its applications, uptake in primary care remains sub-optimal and there are concerns related to the way in which race is factored into interpretation. Moving forward, these failings must be addressed, and innovations like Internet-enabled portable spirometers may present novel opportunities. We must also consider the physiologic and practical limitations inherent to spirometry and further investigate complementary technologies such as respiratory oscillometry and other emerging technologies that assess lung function. Through an exploration of the storied history of spirometry, we can better contextualize its current landscape and appreciate the trends that have repeatedly arisen over time. This may help to improve our current use of spirometry and may allow us to anticipate the obstacles confronting emerging pulmonary function technologies.

Lung Clearance Index in Children with Cystic Fibrosis during Pulmonary Exacerbation

(1) Background: Pulmonary exacerbation (PEx) is one of the main factors affecting the quality of life and life expectancy in patients with cystic fibrosis (CF). Our study aimed to evaluate the change in selected pulmonary function parameters, including lung clearance index (LCI), in patients with CF diagnosed with PEx. (2) Methods: We enrolled 40 children with CF aged 6–17. They performed spirometry and multiple breath nitrogen washout (MBNW) tests during a stable condition period at the beginning and the end of intravenous antibiotic treatment. (3) Results: LCI increased by 65% and FEV₁ decreased by ≥10% in 40% of patients with CF during PEx. An absolute change in LCI between a stable condition period and PEx was 1.05 (±1.92) units, which corresponds to a relative change of 11.48% (±18.61) of the baseline. The relative decrease in FEV₁ was −9.22% (±12.00) and the z-score was −0.67 (±1.13). After the PEx treatment, FEV₁ increased by 11.05% (±9.04) on average, whereas LCI decreased by 1.21 ± 1.59 units on average, which represented 9.42% ± 11.40 compared to the value at the beginning of PEx. (4) Conclusions: The change in LCI captures a higher proportion of events with functional impairment than FEV₁ in school-age children with CF.

The cystic fibrosis lung microenvironment alters antibiotic activity: causes and effects

Chronic airway colonisation by Pseudomonas aeruginosa, a hallmark of cystic fibrosis (CF) lung disease, is associated with increased morbidity and mortality and despite aggressive antibiotic treatment, P. aeruginosa is able to persist in CF airways. In vitro antibiotic susceptibility assays are poor predictors of antibiotic efficacy to treat respiratory tract infections in the CF patient population and the selection of the antibiotic(s) is often made on an empirical base. In the current review, we discuss the factors that are responsible for the discrepancies between antibiotic activity in vitro and clinical efficacy in vivo We describe how the CF lung microenvironment, shaped by host factors (such as iron, mucus, immune mediators and oxygen availability) and the microbiota, influences antibiotic activity and varies widely between patients. A better understanding of the CF microenvironment and population diversity may thus help improve in vitro antibiotic susceptibility testing and clinical decision making, in turn increasing the success rate of antibiotic treatment.

Olfactory dysfunction in cystic fibrosis: Impact of CFTR modulator therapy

BACKGROUND

Elexacaftor-tezacaftor-ivacaftor (ETI) improves pulmonary health and chronic rhinosinusitis (CRS) for people with cystic fibrosis (PwCF), however its impact on olfaction has not been investigated. Olfactory dysfunction impairs quality-of-life (QOL). This study evaluated the impact of ETI on multiple olfactory metrics.

METHODS

Adult PwCF/CRS with CF transmembrane conductance regulator genotype F508del/F508del or F508del/minimal function who clinically initiated ETI participated in a prospective, observational study. Endpoints included changes after 6 months of ETI in quantitative olfactory function (Smell Identification Test, SIT), olfactory QOL (Questionnaire of Olfactory Disorders, QOD) and percent olfactory cleft opacification (%OCO), representing superior nasal cavity inflammation where afferent olfactory neurons are concentrated.

RESULTS

30 PwCF/CRS met inclusion criteria; 25 completed the study. Mean ETI adherence was 93%. At baseline, participants were hyposmic (mean SIT 31.3), had significant %OCO (mean 65.6%), yet reported non-impaired olfactory QOL (mean QOD 6.1). At follow-up, mean SIT worsened mildly (p=0.009), mean %OCO remained stable (p=0.46), and mean QOD improved modestly (p=0.008). No outcomes were impacted by prior modulator use, genotype, nasal polyps, or CF-related diabetes. Prior sinus surgery was associated with QOD improvement (p=0.04). Increased (worse) baseline QOD scores and %OCO were associated with greater improvements (p<0.003), but not SIT (p=0.44).

CONCLUSIONS

ETI was not associated with improvement in quantitative olfaction or olfactory cleft opacification after 6 months. PwCF/CRS have hyposmia but do not report impairment in olfactory QOL. Further study to investigate mechanisms explaining olfactory dysfunction and whether olfaction improves with greater duration of ETI or in younger age groups is warranted.

Impact of CFTR Therapy on Chronic Rhinosinusitis and Health Status: Deep Learning CT Analysis and Patient Reported Outcomes

RATIONALE

Elexacaftor/tezacaftor/ivacaftor (ETI) in triple combination improves pulmonary health for people with cystic fibrosis (PwCF) however its impact on objective measures of sinus disease and health utility is unestablished.

OBJECTIVES

To evaluate the impact of ETI on chronic rhinosinusitis (CRS) and general health status incorporating computed tomography (CT), quality-of-life (QOL) and productivity loss.

METHODS

Adult PwCF+CRS with CF transmembrane conductance regulator genotype F508del/F508del or F508del/minimal function who clinically initiated ETI participated in a prospective, observational study. The primary endpoint was change in percent sinus CT opacification (%SO) after 6 months of ETI assessed via deep learning-based methods. Secondary endpoints included changes in sinonasal QOL, health utility value and productivity loss, which were evaluated monthly via validated metrics.

RESULTS

30 PwCF provided baseline data; 25 completed the study. At baseline, the cohort had substantial CRS, with mean 22-question SinoNasal Outcome Test (SNOT-22) score 33.1 and mean sinus CT %SO 63.7%. At 6-month follow-up, %SO improved by mean 22.9% (p<0.001). %SO improvement trended toward greater magnitude for those naïve to prior modulator therapy (p=0.09). Mean SNOT-22 scores and health utility improved by 15.3 and 0.068 [6.8%] (all p<0.007). Presenteeism, activity impairment and overall productivity loss improved (all p<0.049). Improvements in SNOT-22 scores and health utility occurred by one month and remained improved over the study.

CONCLUSIONS

ETI is associated with substantial improvements in sinus CT opacification and productivity loss, and clinically meaningful improvements in sinonasal QOL and health utility. Most improvements were rapid, robust and durable over the study.

Time to get serious about the detection and monitoring of early lung disease in cystic fibrosis

Structural and functional defects within the lungs of children with cystic fibrosis (CF) are detectable soon after birth and progress throughout preschool years often without overt clinical signs or symptoms. By school age, most children have structural changes such as bronchiectasis or gas trapping/hypoperfusion and lung function abnormalities that persist into later life. Despite improved survival, gains in forced expiratory volume in one second (FEV₁) achieved across successive birth cohorts during childhood have plateaued, and rates of FEV₁ decline in adolescence and adulthood have not slowed. This suggests that interventions aimed at preventing lung disease should be targeted to mild disease and commence in early life. Spirometry-based classifications of 'normal' (FEV₁≥90% predicted) and 'mild lung disease' (FEV₁ 70%-89% predicted) are inappropriate, given the failure of spirometry to detect significant structural or functional abnormalities shown by more sensitive imaging and lung function techniques. The state and readiness of two imaging (CT and MRI) and two functional (multiple breath washout and oscillometry) tools for the detection and monitoring of early lung disease in children and adults with CF are discussed in this article.Prospective research programmes and technological advances in these techniques mean that well-designed interventional trials in early lung disease, particularly in young children and infants, are possible. Age appropriate, randomised controlled trials are critical to determine the safety, efficacy and best use of new therapies in young children. Regulatory bodies continue to approve medications in young children based on safety data alone and extrapolation of efficacy results from older age groups. Harnessing the complementary information from structural and functional tools, with measures of inflammation and infection, will significantly advance our understanding of early CF lung disease pathophysiology and responses to therapy. Defining clinical utility for these novel techniques will require effective collaboration across multiple disciplines to address important remaining research questions. Future impact on existing management burden for patients with CF and their family must be considered, assessed and minimised.To address the possible role of these techniques in early lung disease, a meeting of international leaders and experts in the field was convened in August 2019 at the Australiasian Cystic Fibrosis Conference. The meeting entitiled 'Shaping imaging and functional testing for early disease detection of lung disease in Cystic Fibrosis', was attended by representatives across the range of disciplines involved in modern CF care. This document summarises the proceedings, key priorities and important research questions highlighted.

Oscillometry of the respiratory system: a translational opportunity not to be missed

Airway oscillometry has become the de facto standard for quality assessment of lung physiology in laboratory animals and has demonstrated its usefulness in understanding diseases of small airways. Nowadays, it is seeing extensive use in daily clinical practice and research; however, a question that remains unanswered is how well physiological findings in animals and humans correlate? Methodological and device differences are obvious between animal and human studies. However, all devices deliver an oscillated airflow test signal and output respiratory impedance. In addition, despite analysis differences, there are ways to interpret animal and human oscillometry data to allow suitable comparisons. The potential with oscillometry is its ability to reveal universal features of the respiratory system across species, making translational extrapolation likely to be predictive. This means that oscillometry can thus help determine if an animal model displays the same physiological characteristics as the human disease. Perhaps more importantly, it can also be useful to determine whether an intervention is effective as well as to understand if it affects the desired region of the respiratory system, e.g., the periphery of the lung. Finally, findings in humans can also inform preclinical scientists and give indications as to what type of physiological changes should be observed in animal models to make them relevant as models of human disease. The present article will attempt to demonstrate the potential of oscillometry in respiratory research, an area where the development of novel therapies is plagued with a failure rate higher than in other disease areas.

The effects of the addition of a new airway clearance device to chest physiotherapy in children with cystic fibrosis pulmonary exacerbations

BACKGROUND

Chest physiotherapy plays a crucial role in managing cystic fibrosis, especially during pulmonary exacerbations. This study evaluated the effects of adding a new airway clearance device to chest physiotherapy in subjects with cystic fibrosis hospitalised due to pulmonary exacerbations.

METHODS

This prospective open-label study was carried out at the Pediatric Cystic Fibrosis Centre in Poland between October 2017 and August 2018. Cystic fibrosis patients aged 10 to 18 years who were admitted to the hospital and required intravenous antibiotic therapy due to pulmonary exacerbations were consecutively allocated (1:1) to either chest physiotherapy alone or chest physiotherapy with a new airway clearance device (Simeox; PhysioAssist). Patients performed spirometry and multiple-breath nitrogen washout for lung clearance index assessment upon admission and prior to discharge.

RESULTS

Forty-eight cystic fibrosis patients were included (24 in each group). Spirometry parameters in both groups improved significantly after intravenous antibiotic therapy. A significant improvement in the maximum expiratory flow at 25% of forced vital capacity was observed only in the group with a new airway clearance device (p < 0.01 vs. baseline). Trends towards a lower lung clearance index ratio were similar in both groups. No adverse events were observed in either group.

CONCLUSIONS

Spirometry parameters increased significantly in cystic fibrosis patients treated for pulmonary exacerbations with intravenous antibiotic therapy and intensive chest physiotherapy. The new airway clearance device was safe and well tolerated when added to chest physiotherapy and may be another option for the treatment of pulmonary exacerbation in cystic fibrosis.

Oscillometry and computed tomography findings in patients with idiopathic pulmonary fibrosis

Although the utility of oscillometry for predicting disease severity in idiopathic pulmonary fibrosis (IPF) had been researched, little has been reported on the mechanism of why respiratory impedance reflects disease severity. In addition, traction bronchiectasis has been considered to reduce respiratory resistance and correlate negatively with airflow obstruction, but this hypothesis has not been validated. The present study aimed to investigate the correlations between oscillometric parameters and fibrosis-related lung abnormalities in IPF and to assess the utility of oscillometry as a surrogate marker for traction bronchiectasis and airflow obstruction.

Eighty Japanese patients with IPF underwent high-resolution computed tomography (HRCT), spirometry, and oscillometry and were retrospectively investigated. Fibrosis-related HRCT findings were scored regarding airspace consolidation, honeycombing, architectural distortion, traction bronchiectasis, and fibrosis. Correlations between the HRCT scores, spirometric parameters, and oscillometric parameters were analysed.

Respiratory reactance correlated positively with all fibrosis-related HRCT scores. Vital capacity and forced vital capacity (FVC) correlated negatively with oscillometric parameters and HRCT scores, reflecting the severity of restrictive ventilatory deficiency. Respiratory resistance was not related to any of the HRCT scores or forced expiratory volume in 1 s/FVC. However, forced expiratory volume in 1 s/FVC correlated positively with HRCT scores, which showed that airflow obstruction became milder as the disease progressed.

In conclusion, respiratory reactance reflects fibrosis and restrictive ventilatory deficiency in IPF. Moreover, respiratory resistance is independent of traction bronchiectasis and airflow obstruction in patients with IPF, which implies that respiratory resistance might reflect different properties of the airways.

Respiratory reactance measured by oscillometry correlates with fibrosis-related computed tomography findings in idiopathic pulmonary fibrosis (IPF). Respiratory resistance is independent of traction bronchiectasis and airflow obstruction in IPF.https://bit.ly/36zoGtf

Evaluation of disease severity in bronchiectasis using impulse oscillometry

Although the diagnostic value of impulse oscillometry (IOS) in bronchiectasis for the differential diagnosis of healthy subjects has been researched, the usefulness of each IOS parameter for predicting disease severity in bronchiectasis has not been thoroughly investigated. In addition, the usefulness of IOS in patients with nontuberculous mycobacteria (NTM) infection has not been reported. This study aimed to determine the predictive significance of respiratory impedance and detect the other most significant IOS parameters for predicting disease severity in bronchiectasis patients and to validate the usefulness of IOS in patients with NTM infection.

A total of 206 patients with bronchiectasis who attended clinics at the National Hospital Organization Osaka Toneyama Medical Center were included. Chest high-resolution computed tomography, spirometry and IOS were performed. Hospital admissions, mortality and disease severity indices for bronchiectasis (Bronchiectasis Severity Index (BSI), FACED, and E-FACED scores) were calculated to assess disease severity. The patients were divided into subgroups with and without NTM infection, and subgroup analyses were performed.

Respiratory reactance, especially resonant frequency (f_res), correlated with both BSI and FACED score better than respiratory resistance. Inspiratory but not expiratory impedance was strongly correlated with BSI, FACED and E-FACED scores. Inspiratory f_res was the most useful predictor, increasing as the disease became more severe. The usefulness of IOS was almost equivalent in patients both with and without NTM infection.

Inspiratory reactance measured by IOS is useful for estimating disease severity in bronchiectasis. Inspiratory f_res best predicts disease severity in bronchiectasis patients both with and without NTM infection.

Inspiratory reactance measured by impulse oscillometry may be useful for estimating disease severity of bronchiectasis. Inspiratory f_res can be used to evaluate severity in the disease both with and without NTM infection.https://bit.ly/3fvG0Rn

Predictive value of the modified Bhalla score for assessment of pulmonary exacerbations in adults with cystic fibrosis

OBJECTIVES

The objective of this study was to analyze the predictive value of the modified Bhalla score in high-resolution computed tomography (HRCT) for assessment of pulmonary exacerbations (PEx) in cystic fibrosis (CF) patients. We also describe the relationship between this score and pulmonary function test results.

METHODS

We performed a multicenter and prospective study where adult patients with CF were included consecutively over 18 months. All patients underwent HRCT with acquisition in inspiration and expiration. The results were analyzed by an expert radiologist who assigned a modified Bhalla score value. Lung function was also assessed, and clinical variables were collected. Follow-up lasted approximately 1 year, and PEx were registered.

RESULTS

The study population comprised 160 subjects selected from 360 CF patients monitored in the participating CF units. The mean age was 28 years, 47.5% were women, and mean forced expiratory volume in 1 s (FEV₁) was 67.5%. The mean global modified Bhalla score was 14.5 ± 0.31 points. Pulmonary function test (PFT) results and the modified Bhalla score correlated well, mainly forced vital capacity (FVC) and FEV₁. We constructed a statistical model based on the overall Bhalla score to predict the number of PEx.

CONCLUSIONS

The overall modified Bhalla score can predict future PEx in CF patients. This useful tool can help to prevent PEx in higher risk patients.

KEY POINTS

• Pulmonary function test results and the modified Bhalla score correlated well with FVC and FEV₁. • The total modified Bhalla score can predict the number of exacerbations in adult CF patients. • Our findings highlight the need to establish a unified protocol for chest HRCT during the follow-up of adult patients with CF in order to anticipate possible complications and determine their impact on pulmonary function.

Long-term pulmonary function testing in pediatric bronchiolitis obliterans syndrome after hematopoietic stem cell transplantation

RATIONALE

Bronchiolitis obliterans syndrome (BOS) is a severe, chronic inflammation of the airways leading to an obstruction of the bronchioles. So far, there are only a few studies looking at the long-term development of pulmonary impairment in children with BOS.

OBJECTIVE

The objective of this study was to investigate the incidence and long-term outcome of BOS in children who underwent allogeneic hematopoietic stem cell transplantation (HSCT).

METHODS

Medical charts of 526 children undergoing HSCT in Frankfurt/Main, Germany between 2000 and 2017 were analyzed retrospectively and as a result, 14 patients with BOS were identified. A total of 271 lung functions (spirometry and body plethysmography), 26 lung clearance indices (LCI), and 46 chest high-resolution computed tomography (HRCT) of these 14 patients with BOS were evaluated.

RESULTS

Fourteen patients suffered from BOS after HSCT (2.7%), whereby three distinctive patterns of lung function impairment were observed: three out of 14 patients showed a progressive lung function decline; two died and one received a lung transplant. In five out of 14 patients with BOS persisted with a severe obstructive and secondarily restrictive pattern in lung function (forced vital capacity [FVC] < 60%, forced expiratory volume in 1 second [FEV1] < 50%, and FEV1/FVC < 0.7) and increased LCI (11.67-20.9), six out of 14 patients recovered completely after moderate lung function impairment and signs of BOS on HRCT. Long-term FVC in absolute numbers was increased indicating that the children still have lung growth.

CONCLUSION

Our results showed that the incidence of BOS in children is low. BOS was associated with high mortality and may lead to persistent obstructive lung disease; although, lung growth continued to exist.

Lung clearance index in healthy volunteers, measured using a novel portable system with a closed circuit wash-in

Introduction

Lung clearance index (LCI) is a sensitive measure of early lung disease, but adoption into clinical practice has been slow. Challenges include the time taken to perform each test. We recently described a closed-circuit inert gas wash-in method that reduces overall testing time by decreasing the time to equilibration. The aim of this study was to define a normative range of LCI in healthy adults and children derived using this method. We were also interested in the feasibility of using this system to measure LCI in a community setting.

Methods

LCI was assessed in healthy volunteers at three hospital sites and in two local primary schools. Volunteers completed three washout repeats at a single visit using the closed circuit wash-in method (0.2% SF₆ wash-in tracer gas to equilibrium, room air washout).

Results

160 adult and paediatric subjects successfully completed LCI assessment (95%) (100 in hospital, 60 in primary schools). Median coefficient of variation was 3.4% for LCI repeats and 4.3% for FRC. Mean (SD) LCI for the analysis cohort (n = 53, age 5–39 years) was 6.10 (0.42), making the upper limit of normal LCI 6.8. There was no relationship between LCI and multiple demographic variables. Median (interquartile range) total test time was 18.7 (16.0–22.5) minutes.

Conclusion

The closed circuit method of LCI measurement can be successfully and reproducibly measured in healthy volunteers, including in out-of-hospital settings. Normal range appears stable up to 39 years. With few subjects older than 40 years, further work is required to define the normal limits above this age.

Lung clearance index in detection of post-transplant bronchiolitis obliterans syndrome

Background

Long-term outcomes after lung transplantation are often limited by the development of obliterative bronchiolitis (OB), which is clinically defined using spirometry as bronchiolitis obliterans syndrome (BOS). Lung clearance index (LCI), derived from multiple breath washout (MBW) testing, is a global measure of ventilation heterogeneity that has previously been shown to be a more sensitive measure of obstructive small airway diseases than spirometry. We aimed to assess the feasibility of LCI in adult lung transplant patients and to compare LCI to BOS grade.

Methods

51 stable adult double-lung transplant recipients performed sulfur hexafluoride MBW in triplicate on a single occasion, using a closed-circuit Innocor device. BOS grades were derived from serial spirometry according to International Society for Heart and Lung Transplantation criteria and, where available, high-resolution computed tomography (HRCT) evidence of OB was recorded.

Results

LCI was successfully performed in 98% of patients. The within-visit coefficient of variation for repeat LCI measurements was 3.1%. Mean LCI increased significantly with BOS grades: no BOS (n=15), LCI 7.6; BOS-0p (n=16), LCI 8.3; BOS-1 (n=11), LCI 9.3; BOS-2-3 (n=9), LCI 13.2 (p<0.001). 27 patients had HRCT within 12 months. LCI in those with HRCT evidence of OB was higher than those without OB (11.1 versus 8.2, p=0.006). 47% patients displayed abnormal LCI (>7) despite a normal forced expiratory volume in 1 s (FEV₁) (>80% of baseline).

Conclusions

LCI measurement in lung transplant recipients is feasible and reproducible. LCI increased with increasing BOS grade. A significant proportion of this cohort had abnormal LCI with preserved FEV₁, suggesting early subclinical small airway dysfunction, and supporting a role for MBW in the early identification of BOS.

[Lung clearance index in cystic fibrosis]

INTRODUCTION

Small airways' involvement in cystic fibrosis (CF) pulmonary disease is a very early event, which can progress sub-clinically and insidiously since it is poorly reflected by commonly used lung function tests.

STATE OF ART

Sensitive and discriminative tools are available to investigate small airways function. However their complexity and/or invasiveness has confined their use to research purposes and to some specialized research teams. By contrast, the multiple breath washout (MBW) test is more affordable and non-invasive. Lung clearance index (LCI), which is the most used derived parameter, is reproducible and much more sensitive than spirometry in detecting small airways disease. However, MBW is operator dependent.

PERSPECTIVES

The recent commercialization of devices assessing LCI launches MBW as a potential tool in routine clinical care, although its use currently remains mostly dedicated to research purposes. However, important differences in LCI between various equipment settings raise a number of theoretical questions. Specific algorithms should be refined and more transparent. Standardization of MBW is still an ongoing process. Whether other MBW derived indices can prove superior over LCI deserves further study.

CONCLUSIONS

In CF, LCI is now a well-established outcome in research settings to detect early lung function abnormalities and new treatment effects, especially in patients with mild lung disease. In these patients, LCI seems an attractive tool for clinicians too. Yet, further investigation is needed to define clinically significant changes in LCI and to which extent this index can be useful in guiding clinical decisions remains to be studied.

Feasibility and challenges of using multiple breath washout in COPD

Background

Lung clearance index (LCI), derived from multiple-breath washout (MBW), is a well-established assessment of ventilation inhomogeneity in cystic fibrosis but has not been widely applied in other conditions characterized by heterogeneous airways disease, such as COPD. The aim of this study was to evaluate the sensitivity, repeatability, and practicality of LCI in patients with COPD.

Methods

Fifty-four COPD patients completed MBW using nitrogen as the washout tracer gas (MBW_N2, measured using an Exhalyzer™ device), spirometry, and plethysmography. Twenty patients repeated MBW_N2, MBW_SF6 (using a separate Innocor™ gas analyzer to measure washout of the exogenous trace sulphur hexafluoride), and spirometry at a second visit ≥24 hours later.

Results

Mean (SD) COPD LCI measured by nitrogen washout (LCI_N2) was 12.1 (2.2); mean (SD) LCI Z-score 5.8 (2.0). LCI_N2 increased across Global Initiative for Obstructive Lung Disease stages 1 to 3 and was abnormal (Z-score >1.65) in all COPD patients, including those with forced expiratory volume in 1 second (FEV₁) ≥80% predicted. LCI was repeatable (median intra-test coefficient of variation 4.1%) and reproducible (limits of agreement -1.8 to 1.6) after mean of 16 days. Functional residual capacity (FRC) measurements were significantly greater using nitrogen than SF₆ or plethysmography: mean FRC measured by nitrogen washout (FRC_N2) 139% predicted versus FRC measured by plethysmography 125% predicted, p<0.0001.

Conclusion

LCI is most suitable as a measure of early airways disease in COPD in those with well-preserved FEV₁, with similar repeatability and limitations to that observed in cystic fibrosis. Using the Exhalyzer system to perform MBW_N2, however, appeared to substantially over-read FRC. This discrepancy needs addressing before FRC_N2 measurements made using this device can be reliably deployed.

Risk factors for lung disease progression in children with cystic fibrosis

To identify potential risk factors for lung disease progression in children with cystic fibrosis (CF), we studied the longitudinal data of all children with CF (aged ≥5 years) registered in the Dutch CF Registry (2009-2014).Lung disease progression was expressed as a decline in lung function (forced expiratory volume in 1 s (FEV₁) % pred) and pulmonary exacerbation rate. Potential risk factors at baseline included sex, age, best FEV₁ % pred, best forced vital capacity % pred, genotype, body mass index z-score, pancreatic insufficiency, medication use (proton pump inhibitors (PPIs), prophylactic antibiotics and inhaled corticosteroids), CF-related diabetes, allergic bronchopulmonary aspergillosis and colonisation with Pseudomonas aeruginosaThe data of 545 children were analysed. PPI use was associated with both annual decline of FEV₁ % pred (p=0.017) and future pulmonary exacerbation rate (p=0.006). Moreover, lower FEV₁ % pred at baseline (p=0.007), prophylactic inhaled antibiotic use (p=0.006) and pulmonary exacerbations in the baseline year (p=0.002) were related to pulmonary exacerbations in subsequent years.In a cohort of Dutch children with CF followed for 5 years, we were able to identify several risk factors for future exacerbations. In particular, the association between PPI use and lung disease progression definitely requires further investigation.

Effect of backpack carrying on forced vital capacity in cystic fibrosis: A randomized crossover-controlled trial

BACKGROUND

Backpack carrying impacts lung function in healthy children but the effect in children with cystic fibrosis (CF) is unknown.

METHODS

Three backpack positions were tested: no backpack (NB), a 12.5% body-weight backpack carried bilaterally (BB) or unilaterally (UB), at rest and during a 10 minute walk. Primary outcome was forced vital capacity (FVC). Secondary outcomes included comparison of cardio-respiratory variables within and between groups.

RESULTS

Nine children with CF (13.3±2.6 years; FEV1 66±22%) and 18 healthy children (13.8±1.8 years; FEV1 107±30%) were included. FVC was reduced with UB compared to NB (68.5±23.3% vs 72.1±24.3%, p = 0.024) in children with CF. FEV1, MIP and MEP decreased more with UB in children with CF than in healthy peers. Increases in VO2, VCO2 and minute ventilation with UB were greater in the CF group during walking.

CONCLUSIONS

Unilateral backpack wearing affects FVC in children with CF and requires greater cardio-respiratory adjustments compared to healthy peers.

Supine posture changes lung volumes and increases ventilation heterogeneity in cystic fibrosis

INTRODUCTION

Lung Clearance Index (LCI) is recognised as an early marker of cystic fibrosis (CF) lung disease. The effect of posture on LCI however is important when considering longitudinal measurements from infancy and when comparing LCI to imaging studies.

METHODS

35 children with CF and 28 healthy controls (HC) were assessed. Multiple breath washout (MBW) was performed both sitting and supine in triplicate and analysed for LCI, Scond, Sacin, and lung volumes. These values were also corrected for the Fowler dead-space to create 'alveolar' indices.

RESULTS

From sitting to supine there was a significant increase in LCI and a significant decrease in FRC for both CF and HC (p<0.01). LCI, when adjusted to estimate 'alveolar' LCI (LCIalv), increased the magnitude of change with posture for both LCIalv and FRCalv in both groups, with a greater effect of change in lung volume in HC compared with children with CF. The % change in LCIalv for all subjects correlated significantly with lung volume % changes, most notably tidal volume/functional residual capacity (Vtalv/FRCalv (r = 0.54,p<0.001)).

CONCLUSION

There is a significant increase in LCI from sitting to supine, which we believe to be in part due to changes in lung volume and also increasing ventilation heterogeneity related to posture. This may have implications in longitudinal measurements from infancy to older childhood and for studies comparing supine imaging methods to LCI.

Developments in multiple breath washout testing in children with cystic fibrosis

BACKGROUND

Lung clearance index (LCI) is becoming recognized as an important addition in the monitoring of pediatric cystic fibrosis (CF). The non-invasive technique is easy to perform in all ages, reproducible and increasingly being used in clinical trials. There is interest in utilizing it within the clinic setting but its current use is mostly as a research tool. The procedure is highly dependent on skilled operators and a relaxed testing environment is key to obtaining good quality measurements.

CONCLUSIONS

Standardization of LCI is part of an ongoing collaborative, multicenter process. This review describes the background to LCI, discusses technical issues and limitations and provides examples of its utility in clinical and research contexts.

Skin Biomarkers for Cystic Fibrosis: A Potential Non-Invasive Approach for Patient Screening

BACKGROUND

Cystic fibrosis (CF) is a disabling genetic disease with an increased prevalence in European heritage populations. Currently, the most used technique for collection of CF samples and diagnosis is provided through uncomfortable tests, with uncertain results, mostly based on chloride concentration in sweat. Since CF mutation induces many metabolic changes in patients, exploring these alterations might be an alternative to visualize potential biomarkers that could be used as interesting tools for further diagnostic upgrade, prioritizing simplicity, low cost, and quickness.

METHODS

This contribution describes an accurate strategy to provide potential biomarkers related to CF, which may be understood as a potential tool for new diagnostic approaches and/or for monitoring disease evolution. Therefore, the present proposal consists of using skin imprints on silica plates as a way of sample collection, followed by direct-infusion high-resolution mass spectrometry and multivariate data analysis, intending to identify metabolic changes in skin composition of CF patients.

RESULTS

Metabolomics analysis allowed identifying chemical markers that can be traced back to CF in patients' skin imprints, differently from control subjects. Seven chemical markers from several molecular classes were elected, represented by bile acids, a glutaric acid derivative, thyrotropin-releasing hormone, an inflammatory mediator, a phosphatidic acid, and diacylglycerol isomers, all reflecting metabolic disturbances that occur due to of CF.

CONCLUSION

The comfortable method of sample collection combined with the identified set of biomarkers represent potential tools that open the range of possibilities to manage CF and follow the disease evolution. This exploratory approach points to new perspectives about the development of diagnostic assay using biomarkers and the management CF.

Functional evaluation of breath: spirometry and body plethysmography comparison in people with cystic fibrosis

[Purpose] The aim of the present study was to establish up-to-date data regarding the lung function of cystic fibrosis (CF) patients. [Subjects and Methods] Forty-eight patients of both genders, with a diagnosis of CF, were recruited. As a result our sample presented, according to the GOLD criteria, 23 patients with mild lung obstruction (FEV_1%pred: 89.86), 16 patients with moderate lung obstruction (FEV_1%pred: 56.1) and 9 patients with severe obstruction (FEV_1%pred: 32.1). [Results] All patients presented normal total lung capacity followed by an important residual volume increase. [Conclusion] Our results were important to illustrate the CF patient’s lung functional status and to improve the health system strategy in treating such individuals.

Metabolomics of pulmonary exacerbations reveals the personalized nature of cystic fibrosis disease

Background. Cystic fibrosis (CF) is a genetic disease that results in chronic infections of the lungs. CF patients experience intermittent pulmonary exacerbations (CFPE) that are associated with poor clinical outcomes. CFPE involves an increase in disease symptoms requiring more aggressive therapy. Methods. Longitudinal sputum samples were collected from 11 patients (n = 44 samples) to assess the effect of exacerbations on the sputum metabolome using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The data was analyzed with MS/MS molecular networking and multivariate statistics. Results. The individual patient source had a larger influence on the metabolome of sputum than the clinical state (exacerbation, treatment, post-treatment, or stable). Of the 4,369 metabolites detected, 12% were unique to CFPE samples; however, the only known metabolites significantly elevated at exacerbation across the dataset were platelet activating factor (PAF) and a related monacylglycerophosphocholine lipid. Due to the personalized nature of the sputum metabolome, a single patient was followed for 4.2 years (capturing four separate exacerbation events) as a case study for the detection of personalized biomarkers with metabolomics. PAF and related lipids were significantly elevated during CFPEs of this patient and ceramide was elevated during CFPE treatment. Correlating the abundance of bacterial 16S rRNA gene amplicons to metabolomics data from the same samples during a CFPE demonstrated that antibiotics were positively correlated to Stenotrophomonas and Pseudomonas, while ceramides and other lipids were correlated with Streptococcus, Rothia, and anaerobes. Conclusions. This study identified PAF and other inflammatory lipids as potential biomarkers of CFPE, but overall, the metabolome of CF sputum was patient specific, supporting a personalized approach to molecular detection of CFPE onset.

Characterizing Lung Disease in Cystic Fibrosis with Magnetic Resonance Imaging and Airway Physiology

Translational investigations in cystic fibrosis (CF) have a need for improved quantitative and longitudinal measures of disease status. To establish a non-invasive quantitative MRI technique to monitor lung health in patients with CF and correlate MR metrics with airway physiology as measured by multiple breath washout (MBW). Data were collected in 12 CF patients and 12 healthy controls. Regional (central and peripheral lung) measures of fractional lung water density (FLD: air to 100% fluid) were acquired both at FRC and TLC on a 1.5T MRI. The median FLD (mFLD) and the FRC-to-TLC mFLD ratio were calculated for each region at both lung volumes. Spirometry and MBW data were also acquired for each subject. Ventilation inhomogeneities were quantified by the lung clearance index (LCI) and by indices S_cond* and S_acin* that assess inhomogeneities in the conducting (central) and acinar (peripheral) lung regions, respectively. MBW indices and mFLD at TLC (both regions) were significantly elevated in CF (p<0.01) compared to controls. The mFLD at TLC (central: R = 0.82) and the FRC-to-TLC mFLD ratio (peripheral: R = -0.77) were strongly correlated with S_cond* and LCI. CF patients had high lung water content at TLC when compared to controls. This is likely due to the presence of retained airway secretions and airway wall edema (more water) and to limited expansions of air trapping areas (less air) in CF subjects. FRC-to-TLC ratios of mFLD strongly correlated with central ventilation inhomogeneities. These combined measures may provide a useful marker of both retained mucus and air trapping in CF lungs.

The Dynamics of Disease Progression in Cystic Fibrosis

In cystic fibrosis, statistical models have been more successful in predicting mortality than the time course of clinical status. We develop a system of partial differential equations that simultaneously track mortality and patient status, with all model parameters estimated from the extensive and carefully maintained database from the Cystic Fibrosis Foundation. Cystic fibrosis is an autosomal recessive disease that leads to loss of lung function, most commonly assessed using the Forced Expiratory Volume in 1 second (FEV1%). This loss results from inflammation secondary to chronic bacterial infections, particularly Pseudomonas aeruginosa, methicillin-sensitive Staphylococcus aureus (MSSA) and members of the virulent Burkholderia complex. The model tracks FEV1% and carriage of these three bacteria over the course of a patient’s life. Analysis of patient state changes from year to year reveals four feedback loops: a damaging positive feedback loop between P. aeruginosa carriage and lower FEV1%, negative feedback loops between P. aeruginosa and MSSA and between P. aeruginosa and Burkholderia, and a protective positive feedback loop between MSSA carriage and higher FEV1%. The partial differential equations built from this data analysis accurately capture the life-long progression of the disease, quantify the key role of high annual FEV1% variability in reducing survivorship, the relative unimportance of short-term bacterial interactions for long-term survival, and the potential benefits of eradicating the most harmful bacteria.

Closed circuit rebreathing to achieve inert gas wash-in for multiple breath wash-out

Multiple breath wash-out (MBW) testing requires prior wash-in of inert tracer gas. Wash-in efficiency can be enhanced by a rebreathing tracer in a closed circuit. Previous attempts to deploy this did not account for the impact of CO₂ accumulation on patients and were unsuccessful. We hypothesised that an effective rebreathe wash-in could be delivered and it would not alter wash-out parameters.

Computer modelling was used to assess the impact of the rebreathe method on wash-in efficiency. Clinical testing of open and closed circuit wash-in–wash-out was performed in healthy controls and adult patients with cystic fibrosis (CF) using a circuit with an effective CO₂ scrubber and a refined wash-in protocol.

Wash-in efficiency was enhanced by rebreathing. There was no difference in mean lung clearance index between the two wash-in methods for controls (6.5 versus 6.4; p=0.2, n=12) or patients with CF (10.9 versus 10.8; p=0.2, n=19). Test time was reduced by rebreathe wash-in (156 versus 230 s for CF patients, p<0.001) and both methods were well tolerated. End wash-in CO₂ was maintained below 2% in most cases.

Rebreathe–wash-in is a promising development that, when correctly deployed, reduces wash-in time and facilitates portable MBW testing. For mild CF, wash-out outcomes are equivalent to an open circuit.

Refinements to wash-in methods permit a faster test and allow use of portable lung clearance index testinghttp://ow.ly/UYHiN

Forced oscillations and respiratory system modeling in adults with cystic fibrosis

Background

The Forced Oscillation Technique (FOT) has the potential to increase our knowledge about the biomechanical changes that occur in Cystic Fibrosis (CF). Thus, the aims of this study were to investigate changes in the resistive and reactive properties of the respiratory systems of adults with CF.

Methods

The study was conducted in a group of 27 adults with CF over 18 years old and a control group of 23 healthy individuals, both of which were assessed by the FOT, plethysmography and spirometry. An equivalent electrical circuit model was also used to quantify biomechanical changes and to gain physiological insight.

Results and discussion

The CF adults presented an increased total respiratory resistance (p < 0.0001), increased resistance curve slope (p < 0.0006) and reduced dynamic compliance (p < 0.0001). In close agreement with the physiology of CF, the model analysis showed increased peripheral resistance (p < 0.0005) and reduced compliance (p < 0.0004) and inertance (p < 0.005). Significant reasonable to good correlations were observed between the resistive parameters and spirometric and plethysmographic indexes. Similar associations were observed for the reactive parameters. Peripheral resistance, obtained by the model analysis, presented reasonable (R = 0.35) to good (R = 0.64) relationships with plethysmographic parameters.

Conclusions

The FOT adequately assessed the biomechanical changes associated with CF. The model used provides sensitive indicators of lung function and has the capacity to differentiate between obstructed and non-obstructed airway conditions. The FOT shows great potential for the clinical assessment of respiratory mechanics in adults with CF.

Discordance between clinical, physiological, and radiological measures in cystic fibrosis

There are several methods available to the clinician to assess severity of lung disease in cystic fibrosis (CF). Here we present a case where several of these modalities appeared to be discordant. As in this case, many assessments of respiratory status may be necessary to fully evaluate patients with CF. Spirometry may be insensitive to significant changes that are apparent both clinically and radiologically, but remains an important marker of short-term change, response to intervention, and prognosis. Chest computed tomography can provide valuable detailed information on the health of the lungs and is more sensitive than spirometry to the changes seen in CF. Longitudinal studies of subjects with disproportionately severe radiological changes may be important to assess whether they are more at risk of precipitous declines in pulmonary function.