Reference ranges for spirometry across all ages: a new approach

A Systematic Literature Review of the Natural History of Respiratory, Swallowing, Feeding, and Speech Functions in Spinal Muscular Atrophy (SMA)

Background

Respiratory and bulbar dysfunctions (including swallowing, feeding, and speech functions) are key symptoms of spinal muscular atrophy (SMA), especially in its most severe forms. Demonstrating the long-term efficacy of disease-modifying therapies (DMTs) necessitates an understanding of SMA natural history.

Objective

This study summarizes published natural history data on respiratory, swallowing, feeding, and speech functions in patients with SMA not receiving DMTs.

Methods

Electronic databases (Embase, MEDLINE, and Evidence-Based Medicine Reviews) were searched from database inception to June 27, 2022, for studies reporting data on respiratory and/or bulbar function outcomes in Types 1-3 SMA. Data were extracted into a predefined template and a descriptive summary of these data was provided.

Results

Ninety-one publications were included: 43 reported data on respiratory, swallowing, feeding, and/or speech function outcomes. Data highlighted early loss of respiratory function for patients with Type 1 SMA, with ventilatory support typically required by 12 months of age. Patients with Type 2 or 3 SMA were at risk of losing respiratory function over time, with ventilatory support initiated between the first and fifth decades of life. Swallowing and feeding difficulties, including choking, chewing problems, and aspiration, were reported in patients across the SMA spectrum. Swallowing and feeding difficulties, and a need for non-oral nutritional support, were reported before 1 year of age in Type 1 SMA, and before 10 years of age in Type 2 SMA. Limited data relating to other bulbar functions were collated.

Conclusions

Natural history data demonstrate that untreated patients with SMA experience respiratory and bulbar function deterioration, with a more rapid decline associated with greater disease severity. This study provides a comprehensive repository of natural history data on bulbar function in SMA, and it highlights that consistent assessment of outcomes in this area is necessary to benefit understanding and approval of new treatments.

Normative value of hyperopia reserve and myopic shift in Chinese children and adolescents aged 3-16 years

BACKGROUND

This research aims to generate normative values of hyperopia reserve and refractive progression as effective tools to estimate the risk of myopia.

METHODS

A 1-year follow-up study was conducted among Chinese children and adolescents aged 3-16 years selected from schools and kinder gardens using cluster sampling. All participants underwent examinations including visual acuity, axial length and cycloplegic autorefraction (1% cyclopentolate). Percentiles of spherical equivalent (SE) were calculated using Lambda-Mu-Sigma (LMS) method. Age-specific refractive progression and hyperopia reserve were determined by backward calculation.

RESULTS

Of 3118 participants, 1702 (54.6%) were boys with a mean baseline age of 7.30 years. The 50th percentile of SE estimated by LMS decreased from 1.04 D at 3 years to -2.04 D at 16 years in boys, while from 1.29 D to -2.81 D in girls. The 1-year refractive progression of myopes (0.81 D) was greater than that of non-myopes (0.51 D). The normative value of hyperopia reserve was 2.64 (range: 2.40 D-2.88 D) at 3 years and -0.35 (range: -0.50 to -0.17) D at 16 years, with the maximum progression of 0.35 D at the age of 6 years.

CONCLUSION

Age-specific normative values of hyperopia reserve and yearly myopic shift in children and adolescents aged 3-16 years were provided, helping identify and monitor myopia and giving prevention in advance.

Diagnosis of Post-Hematopoietic Stem Cell Transplantation Bronchiolitis Obliterans Syndrome in Children: Time for a Rethink?

Hematopoietic stem cell transplantation (HSCT) is undertaken in children with the aim of curing a range of malignant and nonmalignant conditions. Unfortunately, pulmonary complications, especially bronchiolitis obliterans syndrome (BOS), are significant sources of morbidity and mortality post-HSCT. Currently, criteria developed by a National Institutes of Health (NIH) working group are used to diagnose BOS in children post-HSCT. Unfortunately, during the development of a recent American Thoracic Society (ATS) Clinical Practice Guideline on this topic, it became apparent that the NIH criteria have significant limitations in the pediatric population, leading to late diagnosis of BOS. Specific limitations include use of an outdated pulmonary function testing reference equation, a reliance on spirometry, use of a fixed forced expiratory volume in 1 second (FEV1) threshold, focus on obstructive defects defined by FEV1/vital capacity, and failure to acknowledge that BOS and infection can coexist. In this review, we summarize the evidence regarding the limitations of the current criteria. We also suggest potential evidence-based ideas for improving these criteria. Finally, we highlight a new proposed criteria for post-HSCT BOS in children that were developed by the authors of the recently published ATS clinical practice guideline, along with a pathway forward for improving timely diagnosis of BOS in children post-HSCT.

Changes in Spirometry Interpretative Strategies: Implications for Classifying COPD and Predicting Exacerbations

BACKGROUND

Recent guidelines for spirometry interpretation recommend both race-neutral reference equations and use of z score thresholds to define severity of airflow obstruction.

RESEARCH QUESTION

How does the transition from race-specific to race-neutral equations impact severity classifications for patients with COPD when using % predicted vs z score thresholds, and do changes in severity correspond to clinical risk?

STUDY DESIGN AND METHODS

This retrospective cohort study included Black and White patients with COPD and available spirometry from the Johns Hopkins Health System. Global Lung Function Initiative (GLI) 2012 (race-specific) equations and GLI Global (race-neutral) equations were used to determine FEV1 % predicted and z score values. Patients were classified as having mild, moderate, or severe disease according to % predicted or z score thresholds. Associations between a change in severity classification from race-specific to race-neutral with COPD exacerbations and all-cause hospitalizations were evaluated using logistic regression.

RESULTS

This cohort included 13,324 patients, of whom 9,232 patients (69.3%) were White (mean age, 65.7 years) and 4,092 patients (30.7%) were Black (mean age, 61.1 years). More Black than White patients showed a change in severity classification between approaches when using % predicted thresholds (20.2% vs 6.1%; P < .001), but not with z score thresholds (12.6% vs 12.3%; P = .68). An increased severity classification with a race-neutral approach was associated with increased risk of exacerbation when using z score thresholds (OR, 2.34; 95% CI, 1.51-3.63), but not when using % predicted thresholds (OR, 1.08; 95% CI, 0.61-1.93). A decreased severity classification with a race-neutral approach was associated with lower risk of exacerbation with both % predicted (OR, 0.49; 95% CI, 0.28-0.87) and z score (OR 0.67; 95% CI, 0.50-0.90) thresholds.

INTERPRETATION

The proportions of Black and White individuals reclassified were similar with z score thresholds, and changes in severity corresponded to clinical risk with z scores. These results support recent recommendations for use of race-neutral equations and z score thresholds for spirometry interpretation.

Lung function decline is mitigated following liver transplantation in people with cystic fibrosis: A retrospective cohort study

There is paucity of literature on the health outcomes following liver transplantation (LT) in people with cystic fibrosis (pwCF). We aim to evaluate changes in lung function following LT in pwCF. We performed a retrospective cohort study of pwCF who underwent LT between 1987 and 2019 in the United States and Canada. Simultaneous lung-liver transplants and individuals who had lung transplant prior to LT were excluded. We analyzed pre-LT and post-LT percent predicted forced expiratory volume in 1 second, body mass index, rates of pulmonary exacerbation, and post-LT overall survival. A total of 402 LT recipients were included. The median age of transplant was 14.9 years and 69.7% of the transplants were performed in children less than 18 years old. The rate of decline in percent predicted forced expiratory volume in 1 second was attenuated after LT from -2.2% to -0.7% predicted per year with a difference of 1.5% predicted per year (95% CI, 0.8, 2.2; p < 0.001). Following LT, the rate of decline in body mass index was reduced, and there were fewer pulmonary exacerbations (0.6 pre vs. 0.4 post; rate ratio 0.7, p < 0.01). The median survival time post-transplant was 13.9 years and the overall probability of survival at 5 years was 77.6%. Those with higher lung function pre-LT had a lower risk of death post-LT, and those with genotypes other than F508 deletion had worse survival. LT in pwCF occurs most often in children and adolescents and is associated with a slower rate of decline in lung function and nutritional status, and a reduction in pulmonary exacerbations.

Relationships between symptoms and lung function in asthma and/or chronic obstructive pulmonary disease in a real-life setting: the NOVEL observational longiTudinal studY

BACKGROUND

The relationships between spirometric assessment of lung function and symptoms (including exacerbations) in patients with asthma and/or chronic obstructive pulmonary disease (COPD) in a real-life setting are uncertain.

OBJECTIVES

To assess the relationships between baseline post-bronchodilator (post-BD) spirometry measures of lung function and symptoms and exacerbations in patients with a physician-assigned diagnosis of asthma and/or COPD.

DESIGN

The NOVEL observational longiTudinal studY (NOVELTY) is a global, prospective, 3-year observational study.

METHODS

Logistic regression analysis was used to evaluate relationships. Spirometry measures were assessed as percent predicted (%pred). Symptoms were assessed at baseline, and exacerbations were assessed at baseline and Year 1.

RESULTS

A total of 11,181 patients in NOVELTY had spirometry data (asthma, n = 5903; COPD, n = 3881; asthma + COPD, n = 1397). A 10% lower post-BD %pred forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) - adjusted for age and sex - were significantly associated with dyspnea (modified Medical Research Council ⩾ grade 2), frequent breathlessness [St George's Respiratory Questionnaire (SGRQ)], frequent wheeze attacks (SGRQ), nocturnal awakening (Respiratory Symptoms Questionnaire; ⩾1 night/week), and frequent productive cough (SGRQ). Lower post-BD %pred FEV1 and, to a lesser extent, lower post-BD %pred FVC were significantly associated with ⩾1 physician-reported exacerbation at baseline or Year 1. This association was stronger in patients with COPD than in those with asthma.

CONCLUSION

In a real-life setting, reduced lung function is consistently associated with symptoms in patients with asthma, COPD, or asthma + COPD. The relationship with exacerbations is stronger in COPD only than in asthma.

TRAIL REGISTRATION

clinicaltrials.gov identifier: NCT02760329 (www.clinicaltrials.gov).

Respiratory System Dynamics

While static mechanical forces govern resting lung volumes, dynamic forces determine tidal breathing, airflow, and changes in airflow and lung volume during normal and abnormal breathing. This section will examine the mechanisms, measurement methodology, and interpretation of the dynamic changes in airflow and lung volume that occur in health and disease. We will first examine how the total work of breathing can be described by the parameters of the equation of motion, which determine the pressure required to move air into and out of the lung. This will include a detailed description of airflow characteristics and airway resistance. Next, we will review the changes in pressure and flow that determine maximal forced inspiration and expiration, which result in the maximal flow-volume loop and the clinically important forced expired volume in 1 second. We will also assess the mechanisms and interpretation of bronchodilator responsiveness, dynamic hyperinflation, and airways hyperresponsiveness.

Inhalation Pharmacodynamics

Pharmacodynamics (PD) is discussed in relation to inhalation exposure to inhaled pharmaceutical and toxic agents. Clearly PD is closely related to pharmacokinetics, and this relation is illustrated with reference to inhaled insulin. PD can be related to pharmacologic responses, and some examples are cited. However, PD can also be thought of as the improvement or deterioration in lung disease state. Some of the major PD endpoints, including histopathology, pulmonary function, and bronchoalveolar lavage are reviewed. Brief reference is also given to other specialty biomarkers of PD response.

Multiple breath washout and oscillometry after allogenic HSCT: a scoping review

Pulmonary chronic graft-versus-host disease (cGVHD) is a substantial cause of pulmonary morbidity and mortality post-haematopoietic stem cell transplantation (HSCT). Current spirometry-based monitoring strategies have significant limitations. Understanding the utility of novel peripheral airway function tests - multiple breath washout (MBW) and oscillometry - is critical in efforts to improve detection, facilitate earlier intervention and improve outcomes. In this scoping review, we identified 17 studies investigating MBW or oscillometry, or both, after allogenic HSCT. Despite small study numbers limiting the ability to draw firm conclusions, several themes were evident. Detectable peripheral airway abnormality in MBW occurred in a substantial proportion prior to HSCT. MBW indices post-HSCT were more frequently abnormal than spirometry when reporting group data and among those with extrapulmonary cGVHD and pulmonary cGVHD. Changes in MBW indices over time may be more indicative of pulmonary complications than absolute values at any given time point. Oscillometry indices were often normal at baseline, but more frequently abnormal in those who developed pulmonary cGVHD. Pooling currently available individual participant data across these studies may improve our ability to formally compare their respective sensitivity and specificity at specific time points and assess the trajectory of MBW and oscillometry indices over time.

Morbidity and treatment costs of cystic fibrosis in a middle-income country

Introduction

: Asian children with cystic fibrosis (CF) managed in Malaysia have significant morbidity with limited access to life-sustaining treatments. We determined the morbidity and treatment cost of CF in a resource-limited country.

Methods

This cross-sectional study included all children diagnosed with CF in our centre. Data on clinical presentation, genetic mutation, serial spirometry results and complications were collected. Out-of-pocket (OOP) and healthcare costs over 1 year were retrieved for patients who were alive. Cohen's d and odds ratio (OR) were used to determine the effect size.

Results

Twenty-four patients were diagnosed with CF. Five patients died at a median (range) age of 18 (0.3-22) years. F508deletion (c. 1521_1523delCTT) was found in 20% of the alleles, while 89% of the variants were detected in nine patients. Body mass index (BMI) Z score was >-1.96 in 70.6% of patients. Two thirds (68%) were colonised with Pseudomonas aeruginosa, and this was associated with lower weight (P = 0.009) and BMI (P = 0.02) Z scores. Only 18% had FEV1 Z scores >-1.96. Early symptom onset (d = 0.74), delayed diagnosis (d = 2.07), a low FEF25-75 Z score (d = 0.82) and a high sweat conductance (d = 1.19) were associated with death. Inpatient cost was mainly from diagnostic tests, while medications contributed to half of the outpatient cost.

Healthcare utilisation cost was catastrophic, amounting to 20% of the total income.

Conclusion

Asian children with CF suffer significant complications such as low weight, low lung function and shortened lifespan. P. aeruginosa colonisation was frequent and associated with poor growth. Healthcare cost to parents was catastrophic.

[The FEV1/VC ratio to define bronchial obstruction: Should we use a fixed ratio or the lower limit of normal?]

INTRODUCTION

While the screening of chronic obstructive lung diseases (COPD, asthma, etc.) constitutes a major public health issue in France and worldwide, simple spirometry appears currently as the key to meeting the challenge. Since description of the forced expiratory maneuver by Robert Tiffeneau in 1947, it has been admitted that the FEV1/VC ratio permits diagnosis obstructive pulmonary diseases. However, the diagnostic criteria for this ratio remain uncertain. The long-lasting debate between advocates of a 0.7 "fixed ratio" (FR) of 0.7 and advocates of the "lower limit of normal" (LLN) remains relevant.

STATE OF THE ARTS

In this general review, we describe the respective advantages of the FR and LLN criteria according to the most recently published studies, and characterize the conditions associated with discrepancies between these criteria.

PERSPECTIVES AND CONCLUSIONS

FR and LLN appear not to share similar diagnosis values and the use of both criteria facilitates proposal of an up-to-date interpretation and diagnosis strategy in the context of first-line spirometry, particularly for patients with FEV1/VC ratio in the "grey zone".

Assessing Asthma Control by Impulse Oscillometry and Fractional Expiratory Nitric Oxide in Children With Normal Spirometry

BACKGROUND

Because spirometric parameters fail to address current status of asthma in some patients, additional tests are required for better evaluation of asthma.

OBJECTIVE

We aimed to test the ability of impulse oscillometry (IOS) and fractional expiratory nitric oxide (FeNO) in identifying inadequately controlled asthma (ICA) that was not uncovered by spirometry.

METHODS

Recruited asthmatic children between ages of 8 and 16 years underwent spirometry, IOS, and FeNO measurements on the same day. Only subjects who had spirometric indices within normal range were included. Asthma Control Questionnaire-6 scores of 0.75 or lower and greater than 0.75 indicated well-controlled asthma (WCA) and ICA. Percent predicted values of IOS parameters and IOS reference values for upper and lower limits of normal (>95th and <5th percentiles, respectively) were calculated on the basis of previously published equations.

RESULTS

There were no significant differences in all spirometric indices between the WCA (n = 59) and the ICA (n = 101) groups. The % predicted values of IOS parameters except resistance at 20 Hz (R20) were significantly different between the 2 groups. Receiver operating characteristic analysis showed that the highest and lowest areas under the curve were 0.81 and 0.67 for the difference between the resistances at 5 Hz and 20 Hz (R5-R20) and R20 in discrimination of ICA versus WCA. The areas under the curve for IOS parameters were improved by combination with FeNO. The better discriminative ability of IOS was also supported by the higher values of the concordance index for the resistance at 5 Hz (R5), R5-R20, the reactance at 5 Hz (X5), and the resonant frequency of reactance than those for spirometric parameters. Compared with those with normal values, subjects with abnormal IOS parameters or high FeNO had significantly higher odds of having ICA.

CONCLUSIONS

The IOS parameters and FeNO were shown to be useful in identifying children with ICA when spirometry was normal.

Comparison of Pulmonary Functions After Induction of Stress Between Post-COVID and Healthy Adults

Since the emergence of COVID in 2019, it has spread worldwide. COVID has affected all the systems of the human body. The present research aimed to assess the effects of COVID-19 on the pulmonary system after stress induction. Healthy and affected individuals between the age of 18 and 40 years were made to perform the 6-minute walk test and their pulmonary functions were compared before and after the stressor. Individuals who were three months post-COVID-19 infection were included as cases. Healthy individuals with no history of COVID were included as controls. The pulmonary functions were performed and noted both at baseline and after the 6-minute walk test. The forced expiratory flow 25 (FEF 25) and peak expiratory flow (PEF) showed statistical significance between both groups (p=0.033 and p=0.007, respectively). FEF 25, 50, and 75, maximum voluntary ventilation (MVV) index, and PEF were positively correlated with all respiratory parameters. Forced expiratory volume % (FEV%) was negatively correlated with vital capacity (VC) and forced vital capacity (FVC). This research helped us establish that the effect on the lungs due to COVID is not due to airway restriction or obstruction but reduced lung volume.

Respiratory features of centronuclear myopathy in the Netherlands

Centronuclear myopathy (CNM) is a heterogeneous group of muscle disorders primarily characterized by muscle weakness and variable degrees of respiratory dysfunction caused by mutations in MTM1, DNM2, RYR1, TTN and BIN1. X-linked myotubular myopathy has been the focus of recent natural history studies and clinical trials. Data on respiratory function for other genotypes is limited. To better understand the respiratory properties of the CNM spectrum, we performed a retrospective study in a non-selective Dutch CNM cohort. Respiratory dysfunction was defined as an FVC below 70% of predicted and/or a daytime pCO2 higher than 6 kPa. We collected results of other pulmonary function values (FEV1/FVC ratio) and treatment data from the home mechanical ventilation centres. Sixty-one CNM patients were included. Symptoms of respiratory weakness were reported by 15/47 (32%) patients. Thirty-three individuals (54%) with different genotypes except autosomal dominant (AD)-BIN1-related CNM showed respiratory dysfunction. Spirometry showed decreased FVC, FEV1 & PEF values in all but two patients. Sixteen patients were using HMV (26%), thirteen of them only during night-time. In conclusion, this study provides insight into the prevalence of respiratory symptoms in four genetic forms of CNM in the Netherlands and offers the basis for future natural history studies.

The Role of Pulmonary Function Testing in the Diagnosis and Management of COPD

Pulmonary function testing (PFT) has a long and rich history in the definition, diagnosis, and management of COPD. For decades, spirometry has been regarded as the standard for diagnosing COPD; however, numerous studies have shown that COPD symptoms, pathology, and associated poor outcomes can occur, despite normal spirometry. Diffusing capacity and imaging studies have called into question the need for spirometry to put the "O" (obstruction) in COPD. The role of exercise testing and the ability of PFTs to phenotype COPD are reviewed. Although PFTs play an important role in diagnosis, treatment decisions are primarily determined by symptom intensity and exacerbation history. Although a seminal study positioned FEV1 as the primary predictor of survival, numerous studies have shown that tests other than spirometry are superior predictors of mortality. In years past, using spirometry to screen for COPD was promulgated; however, this only seems appropriate for individuals who are symptomatic and at risk for developing COPD.

A randomized controlled trial of presatovir for respiratory syncytial virus after lung transplant

BACKGROUND

Respiratory syncytial virus (RSV) infection in lung transplant recipients is associated with high morbidity. This study evaluated the RSV fusion inhibitor presatovir in RSV-infected lung transplant recipients.

METHODS

In this international Phase 2b, randomized, double-blind, placebo-controlled trial (NCT02534350), adult lung transplant recipients with symptomatic confirmed RSV infection for ≤7 days received oral presatovir 200 mg on day 1 and 100 mg daily on days 2 to 14, or placebo (2:1), with follow-up through day 28. There were 2 coprimary endpoints: time-weighted average change in nasal RSV load from day 1 to 7, calculated from nasal swabs, in the full analysis set ([FAS]; all patients who received study drug and had quantifiable baseline nasal RSV load) and time-weighted average change in nasal RSV load from day 1 to 7 in the subset of patients with pretreatment symptom duration at the median or shorter of the FAS. Secondary endpoints were changes in respiratory infection symptoms assessed using the Influenza Patient-Reported Outcomes questionnaire and lung function measured by spirometry.

RESULTS

Sixty-one patients were randomized, 40 received presatovir, 20 placebo, and 54 were included in efficacy analyses. Presatovir did not significantly improve the primary endpoint in the FAS (treatment difference [95% CI], 0.10 [-0.43, 0.63] log10 copies/ml; p = 0.72) or the shorter symptom-duration subgroup (-0.12 [-0.94, 0.69] log10 copies/ml; p = 0.76). Secondary endpoints were not different between presatovir and placebo groups. Presatovir was generally well tolerated.

CONCLUSIONS

Presatovir treatment did not significantly improve change in nasal RSV load, symptoms, or lung function in lung transplant recipients.

Routine FEV1 measurement is essential in diagnosis and monitoring of childhood asthma: myth or maxim?

Childhood asthma is a common condition in children. This review describes the evidence from seven asthma guidelines for using spirometry in the diagnosis and monitoring of childhood asthma. All guidelines recommend spirometry as the primary test to be performed for diagnosing asthma in children aged >5 years. Spirometry is often normal in children with asthma. Guidelines are not consistent with respect to whether forced expiratory volume in 1 s (FEV1) or FEV1/forced vital capacity (FVC) should be measured, or their threshold for "abnormal" spirometry, and we describe the sensitivity and specificity for these different cut-offs. The role of spirometry in monitoring asthma is less clear in the guidelines, and some do not suggest spirometry should be done. There is no consensus on what spirometric measurement should be used, how often it should be measured and what is a minimum clinically important change in spirometry. The role of spirometry in diagnosing asthma is more clearly established when compared to its role in monitoring asthma. The potential of spirometry to aid decision making for asthma diagnosis and monitoring in children remains to be fully evaluated.

Educational aims

To provide knowledge of the commonly used guidelines for asthma diagnosis and management.To give insight into the opportunities and challenges in using spirometry to diagnose and monitor asthma in children.To provide an understanding of the precision of spirometry for diagnosing asthma.

Cough sound-based estimation of vital capacity via cough peak flow using artificial neural network analysis

This study presents a novel approach for estimating vital capacity using cough sounds and proposes a neural network-based model that utilizes the reference vital capacity computed using the lambda-mu-sigma method, a conventional approach, and the cough peak flow computed based on the cough sound pressure level as inputs. Additionally, a simplified cough sound input model is developed, with the cough sound pressure level used directly as the input instead of the computed cough peak flow. A total of 56 samples of cough sounds and vital capacities were collected from 31 young and 25 elderly participants. Model performance was evaluated using squared errors, and statistical tests including the Friedman and Holm tests were conducted to compare the squared errors of the different models. The proposed model achieved a significantly smaller squared error (0.052 L², p < 0.001) than the other models. Subsequently, the proposed model and the cough sound-based estimation model were used to detect whether a participant's vital capacity was lower than the typical lower limit. The proposed model demonstrated a significantly higher area under the receiver operating characteristic curve (0.831, p < 0.001) than the other models. These results highlight the effectiveness of the proposed model for screening decreased vital capacity.

Development and validation of predictive equations for spirometry in Portuguese children

Background

There are no data on lung function reference values for Portuguese children, and the contribution from the Portuguese data set in the Global Lung Function Initiative (GLI) is scant.

Objectives

We aimed to estimate new up-to-date reference values for Portuguese children by fitting a multivariable regression model to a general population sample. Further, we intended to assess the external validity of the obtained reference values and to compare them to the GLI reference values.

Methods

A random sample of 858 children from 20 primary schools were screened by health questionnaire, physical examination, and spirometry. Spirometric parameters recorded were FVC, FEV1, and FEF25-75. Multiple regression models were used to derive reference equations.

Results

Overall, 481 children, aged between 7 and 12 years, 267 boys (55.5%), were included. Boys had higher values for FVC and FEV1 than girls (P < .05). The strongest correlation was found for FVC with height (r = 0.71 for boys and 0.70 for girls), while the lowest correlation was observed in both sexes for FEF25-75 with age (r = 0.23). Height was the most significant predictor of FVC, FEV1, and FEF25-75 in our models. Weight and body mass index were not significant predictors for boys but had a significant effect on girls' equations for all spirometry parameters. Compared to obtained reference equations with GLI, they performed better for FVC in boys, FEV1 in girls, and FEF25-75 in both boys and girls.

Conclusion

We offer up-to-date reference values of spirometry for Portuguese children that can be used in clinical practice and research.

Clinimetric Properties of Outcome Measures in Bronchiectasis

Rationale: There is a lack of outcome measures with robust clinimetric properties in bronchiectasis. Objectives: To determine the clinimetric properties (reliability over 1 year during clinical stability and responsiveness over the course of antibiotics for pulmonary exacerbation) of objective and patient-reported outcome measures. Methods: This multicenter cohort study included adults with bronchiectasis from seven hospitals in the United Kingdom. Participants attended four visits, 4 months apart over 1 year while clinically stable and at the beginning and end of exacerbation and completed lung function (spirometry and multiple breath washout), provided a blood sample for C-reactive protein (CRP) measurement, and completed health-related quality of life (HRQoL) questionnaires (Quality of Life-Bronchiectasis, St. George's Respiratory Questionnaire, and EuroQoL 5-Dimensions 5-Levels). Results: Participants (n = 132) had a mean (standard deviation) age of 66 (11) years, and 64% were female. Lung function parameters (forced expiratory volume in one second [FEV1], standard lung clearance index [LCI2.5]) were reliable over time [coefficient of variation (CV): <10%]). Regarding responsiveness, FEV1 demonstrated better properties than LCI2.5; therefore, a clear justification for the use of LCI2.5 in future trials is needed. CRP was less reliable (CV > 20%) over time than FEV1 and LCI2.5, and whereas CRP had a large mean change between the start and end of an exacerbation, this may have been driven by a small number of patients having a large change in CRP. Reliability of HRQoL questionnaires and questionnaire domains ranged from acceptable (CV: 20-30%) to good (CV: 10-20%), and HRQoL were responsive to treatment of exacerbations. Considering the specific questionnaire domain relevant to the intervention and its associated clinimetric properties is important. Additional statistics will support future power and/or sample size analysis. Conclusions: This information on the clinimetric properties of lung function parameters, CRP, and HRQoL parameters should be used to inform the choice of outcome measures used in future bronchiectasis trials.

Post-TB health and wellbeing

TB affects around 10.6 million people each year and there are now around 155 million TB survivors. TB and its treatments can lead to permanently impaired health and wellbeing. In 2019, representatives of TB affected communities attending the '1st International Post-Tuberculosis Symposium´ called for the development of clinical guidance on these issues. This clinical statement on post-TB health and wellbeing responds to this call and builds on the work of the symposium, which brought together TB survivors, healthcare professionals and researchers. Our document offers expert opinion and, where possible, evidence-based guidance to aid clinicians in the diagnosis and management of post-TB conditions and research in this field. It covers all aspects of post-TB, including economic, social and psychological wellbeing, post TB lung disease (PTLD), cardiovascular and pericardial disease, neurological disability, effects in adolescents and children, and future research needs.

Childhood to adulthood: Accounting for age dependence in healthy-reference distributions in 129 Xe gas-exchange MRI

PURPOSE

Xenon-129 (¹²⁹ Xe) gas-exchange MRI is a pulmonary-imaging technique that provides quantitative metrics for lung structure and function and is often compared to pulmonary-function tests. Unlike such tests, it does not normalize to predictive values based on demographic variables such as age. Many sites have alluded to an age dependence in gas-exchange metrics; however, a procedure for normalizing metrics has not yet been introduced.

THEORY

We model healthy reference values for ¹²⁹ Xe gas-exchange MRI against age using generalized additive models for location, scale, and shape (GAMLSS). GAMLSS takes signal data from an aggregated heathy-reference cohort and fits a distribution with flexible median, variation, skewness, and kurtosis to predict age-dependent centiles. This approach mirrors methods by the Global Lung Function Initiative for modeling pulmonary-function test data and applies it to binning methods widely used by the ¹²⁹ Xe MRI community to interpret and quantify gas-exchange data.

METHODS

Ventilation, membrane-uptake, red blood cell transfer, and red blood cell:membrane gas-exchange metrics were collected on 30 healthy subjects over an age range of 5 to 68 years. A GAMLSS model was fit against age and compared against widely used linear and generalized-linear binning ¹²⁹ Xe MRI analysis schemes.

RESULTS

All 4 gas-exchange metrics had significant skewness, and membrane-uptake had significant kurtosis compared to a normal distribution. Age has significant impact on distribution parameters. GAMLSS-binning produced narrower bins compared to the linear and generalized-linear binning schemes and distributed signal data closer to a normal distribution.

CONCLUSION

The proposed "proof-of-concept" GAMLSS-binning approach can improve diagnostic accuracy of ¹²⁹ Xe gas-exchange MRI by providing a means of modeling voxel distribution data against age.

Developing Fractional Exhaled Nitric Oxide Predicted and Upper Limit of Normal Values for a Disadvantaged Population

BACKGROUND

Fractional exhaled nitric oxide (Feno), used as a biomarker, is influenced by several factors including ethnicity. Normative data are essential for interpretation, and currently single cutoff values are used in children and adults.

RESEARCH QUESTION

Accounting for factors that influence Feno, (1) what are appropriate predicted and upper limit of normal (ULN) Feno values in an underserved population (First Nations Australians), (2) how do these values compare with age-based interpretive guidelines, and (3) what factors influence Feno and what is the size of the effect?

STUDY DESIGN AND METHODS

Feno data of First Nations Australians (age < 16 years, n = 862; age ≥ 16 years, n = 348) were obtained. Medical history using participant questionnaires and medical records were used to define healthy participants. Flexible regression using spline functions, as used by the Global Lung Function Initiative, were used to generate predicted and ULN values.

RESULTS

Look-up tables for predicted and ULN values using age (4-76 years) and height (100-200 cm) were generated and are supplied with a calculator for clinician use. In healthy First Nations children (age < 18 years), ULN values ranged between 25 and 60 parts per billion (ppb) when considering only biologically plausible age and height combinations. For healthy adults, ULN values ranged between 39 and 88 ppb. Neither the current Feno interpretation guidelines, nor the currently recommended cutoff of 50 ppb for First Nations children 16 years of age or younger were appropriate for use in this cohort. Our modelling revealed that predicted and ULN values of healthy participants varied nonlinearly with age and height.

INTERPRETATION

Because single pediatric, adult, or all-age Feno cutoff values used by current interpretive guidelines to define abnormality fail to account for factors that modify Feno values, we propose predicted and ULN values for First Nations Australians 4 to 76 years of age. Creating age- and height-adjusted predicted and ULN values could be considered for other ethnicities.

Spirometry Reference Equations Including Existing and Novel Parameters

Introduction

Spirometry is an essential component of pulmonary function testing, with interpretation dependent upon comparing results to normal. Reference equations for mean and lower limit of normal (LLN) are available for usual parameters, including forced vital capacity (FVC), forced expiratory volume in the first second of an FVC maneuver (FEV1), and FEV1/FVC. However, standard parameters do not fully characterize the flow-volume loop and equations are unavailable for the upper limit of normal (ULN). The aim of this study was to develop reference equations for existing and novel spirometry parameters, which more fully describe the flow-volume loop, and to compare these to previously reported equations.

Methods

Data from healthy participants in NHANES III was used to derive reference equations for existing and novel spirometry parameters accounting for birth sex, age, height, and ethnicity (Caucasian, Mexican American, Black) for ages 8 to 90 years. An iterative process determined %predicted LLN and ULN. Equations were compared to published reported equations.

Results

Reference equations were developed for mean, LLN and ULN for existing and novel spirometry parameters for ages 8 to 90. The derived equations closely match mean values of previously published equations, but more closely fit the LLN. Mexican-American and Caucasian values were similar (within 2%) so they were combined, while Black relative to Caucasian/Mexican-American values were lower for some parameters.

Conclusion

These reference equations, which account for birth sex, age, height, and ethnicity for existing and novel spirometry parameters, provide a more comprehensive and quantitative evaluation of spirometry and the flow-volume curve.

Pulmonary function is associated with frailty, hospitalization and mortality in older people: 5-year follow-up

BACKGROUND

The relationship between pulmonary impairment and frailty has rarely been studied in community-dwelling older adults.

OBJECTIVE

This study aimed to analyze the association between pulmonary function and frailty (prevalent and incident), identifying the best cut-off points to detect frailty and its association with hospitalization and mortality.

METHODS

A longitudinal observational cohort study with 1188 community-dwelling older adults was taken from the Toledo Study for Healthy Aging. The forced expiratory volume in the first second (FEV₁) and the forced vital capacity (FVC) were measured with spirometry. Frailty was evaluated using the Frailty Phenotype and Frailty Trait Scale 5. Associations between pulmonary function and frailty, hospitalization and mortality in a 5-year follow-up and the best cut-off points for FEV₁ and FVC were analyzed.

RESULTS

FEV₁ and FVC were associated with frailty prevalence (OR from 0.25 to 0.60), incidence (OR from 0.26 to 0.53), and hospitalization and mortality (HR from 0.35 to 0.85). The cut-off points of pulmonary function identified in this study: FEV1 (≤1.805 L for male and ≤1.165 L for female) and FVC (≤2.385 L for male and ≤1.585 L for female) were associated with incident frailty (OR: 1.71-4.06), hospitalization (HR: 1.03-1.57) and mortality (HR: 2.64-5.17) in individuals with and without respiratory diseases (P < 0.05 for all).

CONCLUSION

Pulmonary function was inversely associated with the risk of frailty, hospitalization and mortality in community-dwelling older adults. The cut-off points for FEV₁ and FVC to detect frailty were highly associated with hospitalization and mortality in the 5-year follow-up, regardless of the existence of pulmonary diseases.

Abnormalities in pulmonary function and volumes in patients with CHD: a systematic review

BACKGROUND

Lung function and cardiac function are naturally correlated by sharing the thoracic cage and handling the whole cardiac output sequentially. However, lung function studies are rare in patients with CHD, although results worthy of investigation could be expected. This review summarises existing studies with the lung function parameters (spirometry and body plethysmography) in CHD patients during the last decade.

METHODS

A systematic review was performed in the relevant database (PubMed, Cochrane, and Scopus) in studies including paediatric and adult patients with CHD where lung parameters (spirometry, body plethysmography) were investigated from January 2010 to December 2020. Two independent reviewers evaluated the studies according to the Study Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies of the National Heart, Lung, and Blood Institute.

RESULTS

Eight studies investigated patients with Fontan palliation including 704 patients (306 female). Four studies included patients after repaired tetralogy of Fallot examining 219 patients (103 female), with one study using double. Further six studies included 3208 (1324 female) children and adults with various CHDs. Overall, four studies were categorised as "good", ten as "fair", and four as "poor". While the measurements were consistently standardised, references to calculate %predicted differed substantially across all studies. All evaluated studies showed reduced forced vital capacity in the majority of CHD patients.

CONCLUSIONS

Many CHD patients have a reduced forced vital capacity independent of their underlying defect. Spirometry should not only follow a standardised measure according to ATS (update 2019) but also stick to the 2012 GLI reference values.

Potential estimation model in French alpine skiing - Individual evolution curve and progression typology

Estimating the potential of alpine skiers is an unresolved question, especially because of the complexity of sports performance. We developed a potential estimation model based solely on the evolution of performance as a function of age. A bayesian mixed model allowed to estimate the potential curve and the age at peak performance for the population (24.81 ± 0.2) and for each individual as the uncertainty around this curve. With Gaussian mixtures, we identified among all the estimates four types of curves, clustered according to the performance level and the progression per age. Relying on the uncertainty calculated on the progression curve the model created also allow to estimate a score and an uncertainty associated with each cluster for all individuals. The results allows to: i) describe and explain the relationship between age and performance in alpine skiing from a species point of view (at 0.87%) and ii) to provide to sport staffs the estimation of the potential of each individual and her/his typology of progression to better detect sports potential. The entire methodology is based on age and performance data, but the progression identified may depend on parameters specific to alpine skiing.

Understanding the experiences of lung volume recruitment among boys with Duchenne muscular dystrophy: A multicenter qualitative study

BACKGROUND

Despite recommendations for regular lung volume recruitment (LVR) use in clinical practice guidelines for children with neuromuscular disease, adherence to LVR is poor. We aimed to describe the experience of LVR by boys with Duchenne muscular dystrophy (DMD), their families, and healthcare providers (HCPs), as well as to identify the barriers and facilitators to LVR use.

METHODS

This multicenter, qualitative study evaluated boys with DMD (n = 11) who used twice-daily LVR as part of a randomized controlled trial, as well as their parents (n = 11), and HCPs involved in the clinical use of LVR (n = 9). Semistructured interviews were conducted to identify participants' understanding of LVR therapy and their beliefs, barriers and facilitators to its use. Thematic analysis was conducted using an inductive approach. A subanalysis compared adherent and nonadherent children.

RESULTS

Seven themes were identified related to participants' beliefs and experiences with LVR: emotional impact, adaptation to LVR, perceived benefits of LVR, routine, family engagement, clinical resources, and equipment-related factors. Strategies to improve adherence were also identified, including education, reinforcement and demonstration of LVR benefit, as well as clinician support. There were no thematic differences between adherent and nonadherent children.

DISCUSSION

Despite the benefits of LVR and positive experiences with it by many families, there remain barriers to adherence to treatment. HCPs need to balance the need for early introduction to give families time to adapt to LVR while ensuring that the benefit of LVR outweighs the burden. Clinician support is important for family engagement.

Ever and cumulative occupational exposure and lung function decline in longitudinal population-based studies: a systematic review and meta-analysis

OBJECTIVES

Adverse occupational exposures can accelerate age-related lung function decline. Some longitudinal population-based studies have investigated this association. This study aims to examine this association using findings reported by longitudinal population-based studies.

METHODS

Ovid Medline, PubMed, Embase, and Web of Science were searched using keywords and text words related to occupational exposures and lung function and 12 longitudinal population-based studies were identified using predefined inclusion criteria. The quality of the studies was assessed using the Newcastle-Ottawa Scale. Lung function decline was defined as annual loss of forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC) or the ratio (FEV₁/FVC). Fixed and random-effects meta-analyses were conducted to calculate pooled estimates for ever and cumulative exposures. Heterogeneity was assessed using the I² test, and publication bias was evaluated using funnel plots.

RESULTS

Ever exposures to gases/fumes, vapours, gases, dusts, fumes (VGDF) and aromatic solvents were significantly associated with FEV₁ decline in meta-analyses. Cumulative exposures for these three occupational agents observed a similar trend of FEV₁ decline. Ever exposures to fungicides and cumulative exposures to biological dust, fungicides and insecticides were associated with FEV₁ decline in fixed-effect models only. No statistically significant association was observed between mineral dust, herbicides and metals and FEV₁ decline in meta-analyses.

CONCLUSION

Pooled estimates from the longitudinal population-based studies have provided evidence that occupational exposures are associated with FEV₁ decline. Specific exposure control and respiratory health surveillance are required to protect the lung health of the workers.

Pulmonary Function in Post-Infectious Bronchiolitis Obliterans in Children: A Systematic Review and Meta-Analysis

Owing to the rarity of post-infectious bronchiolitis obliterans (PIBO), pulmonary function in children with PIBO has been mainly investigated in small-sample sized studies. This systematic review and meta-analysis investigated pulmonary function in children with PIBO, regardless of age at respiratory insult and PIBO diagnosis. A systematic literature search revealed 16 studies reporting pulmonary function data in 480 children with PIBO. Levels of key pulmonary function parameters were summarized by pooled mean difference (MD) only in children with PIBO, and a random effect model was used. Pooled MDs (95% confidence interval [CI]) for FEV₁, FVC, and FEF_25-75% were 51.4, (44.2 to 58.5), 68.4 (64.4 to 72.3), and 26.5 (19.3 to 33.6) % predicted, respectively, with FEV₁/FVC of 68.8% (62.2 to 75.4). Pooled MDs (95% CI) of the z-scores for FEV₁, FVC, and FEF_25-75% were -2.6 (-4.2 to -0.9), -1.9 (-3.2 to -0.5), and -2.0 (-3.6 to -0.4). Pooled MD (95% CI) for the diffusion capacity of the lungs for carbon monoxide from two studies was 64.9 (45.6 to 84.3) % predicted. The post-bronchodilator use change in the FEV₁ in three studies was 6.1 (4.9 to 7.2). There was considerable heterogeneity across the studies. PIBO is associated with moderately impaired pulmonary function, and this review facilitates an understanding of PIBO pathophysiology in children.

The predictive value of pulmonary function test before transplantation for chronic pulmonary graft-versus-host-disease after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Pulmonary chronic graft-versus-host disease (cGVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a devastating complication and often diagnosed at a late stage when lung dysfunction is irreversible. Identifying patients before transplant who are at risk may offer improved strategies to decrease the mortality. Bronchiolitis obliterans syndrome (BOS) is the typical manifestation of pulmonary cGVHD, which is clinically diagnosed by pulmonary function test (PFT). This study aimed to evaluate the predictive value of PFT pre-HSCT for BOS.

METHODS

A single center cohort of 923 allo-HSCT recipients was analyzed, including 15 patients who developed pulmonary cGVHD. Kaplan-Meier method was used to analyze the 3 year progression free survival and 3 year overall survival (OS). A Cox regression model was applied for univariate and multivariate models.

RESULTS

The 3 year cumulative incidence of pulmonary cGVHD was 2.04% (95% CI 1.00-3.08%). According to the cut-off values determined by receiver operator characteristic curve, higher ratio of forced expiratory volume during one second to forced vital capacity (FEV1/FVC) pre-HSCT was correlated to a lower incidence of pulmonary cGVHD [0.91% (95% CI 0.01-1.81%) vs. 3.61% (95% CI 1.30-5.92%), P < 0.01], and so as peak expiratory flow to predictive value (PEF/pred) [0.72% (95% CI 0-1.54%) vs. 3.74% (95% CI 1.47-6.01%), P < 0.01]. Multivariate analysis showed that FEV1/FVC (HR = 3.383, P = 0.047) and PEF/pred (HR = 4.426, P = 0.027) were independent risk factors for onset of BOS. Higher FEV1/FVC and PEF/pred level were related to a significantly decreased 3 year non-relapse mortality. The 3 year OS was superior in patients with higher PEF/pred [78.17% (95% CI 74.50-81.84%) vs. 71.14% (95% CI 66.08-76.20%), P = 0.01], while FEV1/FVC did not show significance difference.

CONCLUSION

Our results suggested that PFT parameters such as PEF/pred and FEV1/FVC could be predictors for pulmonary cGVHD and even transplant outcomes before HSCT.

Spirometry profiles among pregnant and non-pregnant African women: a cross-sectional study

BACKGROUND

Spirometry is a commonly used lung function test. It assesses respiratory functions by measuring the air volume and the rate at which a person can exhale from lungs filled to their total capacity. The most helpful spirometry parameters are: forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and peak expiratory flow (PEF). Pregnancy derives an altered physiological state due to hormonal and anatomical changes that affect the respiratory system. Despite that, spirometry is less commonly done during pregnancy, and if done, test results are evaluated against non-pregnancy references.

OBJECTIVE

This study aimed to explore spirometry profiles in pregnant and non-pregnant women and describe their differences.

METHODOLOGY

This cross-sectional study involved age-matched pregnant and non-pregnant participants recruited from Mnazi Moja ANC and Muhimbili University (MUHAS). A digital spirometer was used to assess respiratory function. Data were entered and analyzed using SPSS version 23. The mean spirometry values of pregnant participants were compared to those of non-pregnant participants using an independent sample t-test. A p-value of < 0.05 was considered statistically significant.

RESULTS

The study included 92 pregnant and 98 non-pregnant participants subjected to spirometry. Both FVC and FEV1 values were significantly lower in pregnant than in non-pregnant participants (2.7 ± 0.5 L vs. 2.9 ± 0.5 L; p < 0.01 and 2.2 ± 0.4 L vs. 2.5 ± 0.4 L; p < 0.01 respectively). In addition, pregnant participants had significantly lower mean PEF values than their non-pregnant counterparts (303 ± 84 L/min versus 353 ± 64 L/min; p < 0.01).

CONCLUSION

Spirometry test values are lower in pregnancy than in non-pregnant participants.

RECOMMENDATIONS

Interpreting the spirometry test values of pregnant women using references obtained from non-pregnant women may be inappropriate. Future studies should evaluate the appropriateness of predicting spirometry values of pregnant women using reference equations derived from non-pregnant women.

Functional Predictors Discriminating Asthma-COPD Overlap (ACO) from Chronic Obstructive Pulmonary Disease (COPD)

Background

A significant proportion of patients with obstructive lung disease have clinical and functional features of both asthma and chronic obstructive pulmonary disease (COPD), referred to as the asthma–COPD overlap (ACO). The distinction of these phenotypes, however, is not yet well-established due to the lack of defining clinical and/or functional criteria. The aim of our investigations was to assess the discriminating power of various lung function parameters on the assessment of ACO.

Methods

From databases of 4 pulmonary centers, a total of 540 patients (231 males, 309 females), including 372 patients with asthma, 77 patients with ACO and 91 patients with COPD, were retrospectively collected, and gradients among combinations of explanatory variables of spirometric (FEV₁, FEV₁/FVC, FEF_25-75), plethysmographic (sR_eff, sG_eff, the aerodynamic work of breathing at rest; sWOB), static lung volumes, including trapped gases and measurements of the carbon monoxide transfer (DL_CO, K_CO) were explored using multiple factor analysis (MFA). The discriminating power of lung function parameters with respect to ACO was assessed using linear discriminant analysis (LDA).

Results

LDA revealed that parameters of airway dynamics (sWOB, sR_eff, sG_eff) combined with parameters of static lung volumes such as functional residual capacity (FRC_pleth) and trapped gas at FRC (V_TG^FRC) are valuable and potentially important tools discriminating between asthma, ACO and COPD. Moreover, sWOB significantly contributes to the diagnosis of obstructive airway diseases, independent from the state of pulmonary hyperinflation, whilst the diffusion capacity for carbon monoxide (DL_CO) significantly differentiates between the 3 diagnostic classes.

Conclusion

The complexity of COPD with its components of interaction and their heterogeneity, especially in discrimination from ACO, may well be differentiated if patients are explored by a whole set of target parameters evaluating, interactionally, flow limitation, airway dynamics, pulmonary hyperinflation, small airways dysfunction and gas exchange disturbances assessing specific functional deficits.

Pediatric 129 Xe Gas-Transfer MRI-Feasibility and Applicability

BACKGROUND

129 Xe gas-transfer MRI provides regional measures of pulmonary gas exchange in adults and separates xenon in interstitial lung tissue/plasma (barrier) from xenon in red blood cells (RBCs). The technique has yet to be demonstrated in pediatric populations or conditions.

PURPOSE/HYPOTHESIS

To perform an exploratory analysis of 129 Xe gas-transfer MRI in children.

STUDY TYPE

Prospective.

POPULATION

Seventy-seven human volunteers (38 males, age = 17.7 ± 15.1 years, range 5-68 years, 16 healthy). Four pediatric disease cohorts.

FIELD STRENGTH/SEQUENCE

3-T, three-dimensional-radial one-point Dixon Fast Field Echo (FFE) Ultrashort Echo Time (UTE).

ASSESSMENT

Breath hold compliance was assessed by quantitative signal-to-noise and dynamic metrics. Whole-lung means and standard deviations were extracted from gas-transfer maps. Gas-transfer metrics were investigated with respect to age and lung disease. Clinical pulmonary function tests were retrospectively acquired for reference lung disease severity.

STATISTICAL TESTS

Wilcoxon rank-sum tests to compare age and disease cohorts, Wilcoxon signed-rank tests to compare pre- and post-breath hold vitals, Pearson correlations between age and gas-transfer metrics, and limits of normal with a binomial exact test to compare fraction of subjects with abnormal gas-transfer. P ≤ 0.05 was considered significant.

RESULTS

Eighty percentage of pediatric subjects successfully completed 129 Xe gas-transfer MRI. Gas-transfer parameters differed between healthy children and adults, including ventilation (0.75 and 0.67) and RBC:barrier ratio (0.31 and 0.46) which also correlated with age (ρ = -0.76, 0.57, respectively). Bone marrow transplant subjects had impaired ventilation (90% of reference) and increased dissolved 129 Xe standard deviation (242%). Bronchopulmonary dysplasia subjects had decreased barrier-uptake (69%). Cystic fibrosis subjects had impaired ventilation (91%) and increased RBC-transfer (146%). Lastly, childhood interstitial lung disease subjects had increased ventilation heterogeneity (113%). Limits of normal provided detection of abnormalities in additional gas-transfer parameters.

DATA CONCLUSION

Pediatric 129 Xe gas-transfer MRI was adequately successful and gas-transfer metrics correlated with age. Exploratory analysis revealed abnormalities in a variety of pediatric obstructive and restrictive lung diseases.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 2.

Air pollution as an early determinant of COPD

COPD is a progressive and debilitating disease often diagnosed after 50 years of age, but more recent evidence suggests that its onset could originate very early on in life. In this context, exposure to air pollution appears to be a potential contributor. Although the potential role of air pollution as an early determinant of COPD is emerging, knowledge gaps still remain, including an accurate qualification of air pollutants (number of pollutants quantified and exact composition) or the "one exposure-one disease" concept, which might limit the current understanding. To fill these gaps, improvements in the field are needed, such as the use of atmosphere simulation chambers able to realistically reproduce the complexity of air pollution, consideration of the exposome, as well as improving exchanges between paediatricians and adult lung specialists to take advantage of reciprocal expertise. This review should lead to a better understanding of the current knowledge on air pollution as an early determinant of COPD, as well as identify the existing knowledge gaps and opportunities to fill them. Hopefully, this will lead to better prevention strategies to scale down the development of COPD in future generations.

Referential equations for pulmonary diffusing capacity using GAMLSS models derived from Japanese individuals with near-normal lung function

Objective

To generate appropriate reference values for the single-breath diffusing capacity of the lungs for carbon monoxide (D_LCO), alveolar volume (V_A), and the transfer coefficient of the lungs for carbon monoxide (K_CO, often denoted as D_LCO/V_A) in the Japanese population. We also intended to assess the applicability of these values for the Japanese population by comparing them to those published by the Global Lung Function Initiative in 2017 (GLI-2017) and previous values.

Methods

In this retrospective study, we measured the spirometric indices, D_LCO, V_A, and K_CO of the Japanese population aged 16–85 years. The lambda, mu, and sigma (LMS) method and the generalized additive models for the location, scale, and shape program in R were used to generate the reference values.

Results

We conducted a total of 390 tests. The GLI-2017 z-scores of D_LCO were approximately zero, whereas those of K_CO and V_A were far from zero. In the present study, the mean square errors of the D_LCO, V_A, and K_CO reference values were lower than the reference values derived from GLI-2017 and previous linear regression equations.

Conclusions

Reference values obtained in this study were more appropriate for our sample than those reported in GLI-2017. Differences between the two equations were attributed to underestimating K_CO (D_LCO / V_A) and overestimating V_A, respectively, by the GLI-2017 for the Japanese population.

Decline in forced vital capacity in subjects with systemic sclerosis-associated interstitial lung disease in the SENSCIS trial compared with healthy reference subjects

BACKGROUND

The forced vital capacity (FVC) of healthy individuals depends on their age, sex, ethnicity and height. Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is characterised by loss of FVC. We compared FVC values in the subjects with SSc-ILD in the SENSCIS trial of nintedanib versus placebo with values from hypothetical matched healthy references.

METHODS

The SENSCIS trial enrolled subjects with SSc with first non-Raynaud symptom in the prior ≤ 7 years, extent of fibrotic ILD on HRCT ≥ 10%, and FVC ≥ 40% predicted. FVC at baseline and decline in FVC over 52 weeks were compared with FVC values in hypothetical healthy reference subjects matched 1:1 to the subjects in the trial for age, sex, ethnicity and height, determined using equations published by the European Respiratory Society Global Lung Function Initiative.

RESULTS

At baseline, mean (SD) FVC was 2460 (737) mL in the nintedanib group (n = 287) compared with 3403 (787) mL in the hypothetical matched healthy references. Mean (SD) FVC was 2544 (817) mL in the placebo group (n = 286) compared with 3516 (887) mL in the hypothetical matched healthy references. Mean (SE) changes in FVC at week 52, i.e., age-related loss of lung function, in the hypothetical healthy references matched to the nintedanib and placebo groups, respectively, were - 26.3 (0.5) mL and - 25.8 (0.5) mL. The difference in the change in FVC at week 52 between the nintedanib group and the hypothetical healthy references was 26.6 mL (95% CI: 1.2, 52.0; p = 0.04). The difference in the change in FVC at week 52 between the placebo group and the hypothetical healthy references was 77.5 mL (95% CI: 51.4, 103.7; p < 0.0001).

CONCLUSIONS

Subjects with SSc-ILD in the SENSCIS trial had impaired lung function at baseline and experienced further deterioration over 52 weeks. The decline in FVC in the placebo group was four-fold greater than in a hypothetical group of matched healthy references, whereas the decline in FVC in patients who received nintedanib was two-fold greater than in hypothetical healthy references. These data highlight the clinical relevance of the slowing of FVC decline provided by nintedanib. Trial registration Registered 5 November 2015, https://clinicaltrials.gov/ct2/show/NCT02597933 .

ERS/ATS technical standard on interpretive strategies for routine lung function tests

BACKGROUND

Appropriate interpretation of pulmonary function tests (PFTs) involves the classification of observed values as within/outside the normal range based on a reference population of healthy individuals, integrating knowledge of physiological determinants of test results into functional classifications and integrating patterns with other clinical data to estimate prognosis. In 2005, the American Thoracic Society (ATS) and European Respiratory Society (ERS) jointly adopted technical standards for the interpretation of PFTs. We aimed to update the 2005 recommendations and incorporate evidence from recent literature to establish new standards for PFT interpretation.

METHODS

This technical standards document was developed by an international joint Task Force, appointed by the ERS/ATS with multidisciplinary expertise in conducting and interpreting PFTs and developing international standards. A comprehensive literature review was conducted and published evidence was reviewed.

RESULTS

Recommendations for the choice of reference equations and limits of normal of the healthy population to identify individuals with unusually low or high results are discussed. Interpretation strategies for bronchodilator responsiveness testing, limits of natural changes over time and severity are also updated. Interpretation of measurements made by spirometry, lung volumes and gas transfer are described as they relate to underlying pathophysiology with updated classification protocols of common impairments.

CONCLUSIONS

Interpretation of PFTs must be complemented with clinical expertise and consideration of the inherent biological variability of the test and the uncertainty of the test result to ensure appropriate interpretation of an individual's lung function measurements.

Functional, transcriptional, and microbial shifts associated with healthy pulmonary aging in rhesus macaques

Older individuals are at increased risk of developing severe respiratory infections. However, our understanding of the impact of aging on the respiratory tract remains limited as samples from healthy humans are challenging to obtain and results can be confounded by variables such as smoking and diet. Here, we carry out a comprehensive cross-sectional study (n = 34 adult, n = 49 aged) to define the consequences of aging on the lung using the rhesus macaque model. Pulmonary function testing establishes similar age and sex differences as humans. Additionally, we report increased abundance of alveolar and infiltrating macrophages and a concomitant decrease in T cells were in aged animals. scRNAseq reveals shifts from GRZMB to IFN expressing CD8⁺ T cells in the lungs. These data provide insight into age-related changes in the lungs’ functional, microbial, and immunological landscape that explain increased prevalence and severity of respiratory diseases in the elderly.

Rhoades et al. describe age-associated functional, microbial, and immunological changes in the lung using the rhesus macaque model. These data will support further studies aimed at designing and testing interventions to mitigate the impact of age-associated shifts in the lung environment to reduce age-related pulmonary disease in the elderly.

Lung function in young adulthood: differences between males and females with asthma

Background

There are phenotypic differences in asthma in males and females. Differences in lung function between the sexes at the peak lung function level in young adulthood are so far not directly addressed. The aim of the present study was to assess lung function in early adulthood in males and females depending on asthma onset and remission.

Methods

Participants were included from the population-based birth cohort BAMSE and classified as having: never asthma, childhood asthma in remission, adolescent onset asthma or persistent asthma. Pre- and post-bronchodilator lung function (in Z-score) and lung clearance index (LCI) were measured at age 24 years. Lung function was compared stratified for sex between the never asthma and asthma groups univariately and in multiple linear regression analyses adjusted for maternal and paternal asthma, maternal smoking during pregnancy, secondary smoking, daily smoking, early respiratory syncytial virus infection, traffic pollution, childhood allergic sensitisation, and body mass index at age 24 years.

Results

All asthma phenotypes were associated with a lower forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) post-bronchodilation at 24 years. This was most pronounced in males with persistent asthma compared to males with never asthma (regression coefficient: −0.503; 95% CI: −0.708– −0.298). Childhood asthma (in remission or persistent) was associated with a lower FEV₁. After adjustment, the associations remained significant for males. For females, the significant associations with lower FEV₁ and FEV₁/FVC remained only for subjects with asthma in remission. Persistent asthma was associated with higher LCI in females.

Conclusions

In females, in contrast to males, the association between asthma and lower lung function was attenuated after adjustment for known risk factors.

Current or previous asthma is associated with lower lung function in early adulthood. In females, in contrast to males, the association between asthma and lower lung function is attenuated after adjustment for known risk factors.https://bit.ly/37vDzzu

Successfully Managed Respiratory Insufficiency in a Patient with a Novel Pathogenic Variant of the BMPER Gene: A Case Report

Bone morphogenetic protein-binding endothelial cell precursor-derived regulator (BMPER) gene mutation presents a disease spectrum ranging from a mild type of ischiospinal dysostosis (ISD) to a more severe type of diaphanospondylodysostosis (DSD). It is known that BMPER gene mutations are very rare, and their resulting clinical manifestations, including musculoskeletal modifications, appear in a spectrum of various types and severity levels. With the development of genetic diagnosis, case reports of patients with specific mutations in the BMPER gene have been published. The most commonly known clinical features are kidney structural problems, including neuroblastoma and renal cysts. Meanwhile, respiratory failure is a common and fatal symptom for patients with BMPER gene mutation, but it does not appear to have been well evaluated or managed so far. We report a case of a confirmed novel mutation of c.1750delT (p.Cys584fs) in the BMPER gene in a female adolescent patient and highlight the importance of the regular assessment of respiratory failure for successful management of this condition.

Routine lung volume recruitment in boys with Duchenne muscular dystrophy: a randomised clinical trial

BACKGROUND

Impaired cough results in airway secretion retention, atelectasis and pneumonia in individuals with Duchenne muscular dystrophy (DMD). Lung volume recruitment (LVR) stacks breaths to inflate the lungs to greater volumes than spontaneous effort. LVR is recommended in DMD clinical care guidelines but is not well studied. We aimed to determine whether twice-daily LVR, compared with standard of care alone, attenuates the decline in FVC at 2 years in boys with DMD.

METHODS

In this multicentre, assessor-blinded, randomised controlled trial, boys with DMD, aged 6-16 years with FVC >30% predicted, were randomised to receive conventional treatment or conventional treatment plus manual LVR twice daily for 2 years. The primary outcome was FVC % predicted at 2 years, adjusted for baseline FVC % predicted, age and ambulatory status. Secondary outcomes included change in chest wall distensibility (maximal insufflation capacity minus FVC) and peak cough flow.

RESULTS

Sixty-six boys (36 in LVR group, 30 in control) were evaluated (median age (IQR): 11.5 years (9.5-13.5), median baseline FVC (IQR): 85% predicted (73-96)). Adjusted mean difference in FVC between groups at 2 years was 1.9% predicted (95% CI -6.9% to 10.7%; p=0.68) in the direction of treatment benefit. We found no differences in secondary outcomes.

CONCLUSION

There was no difference in decline in FVC % predicted with use of twice-daily LVR for boys with DMD and relatively normal lung function. The burden associated with routine LVR may outweigh the benefit. Benefits of LVR to maintain lung health in boys with worse baseline lung function still need to be clarified.

TRIAL REGISTRATION NUMBER

NCT01999075.

Factors affecting postoperative pulmonary function deterioration in adolescent idiopathic scoliosis: A prospective study using 3-dimensional image reconstruction by biplanar stereoradiography

This study aimed both to evaluate rib cage parameters in patients with adolescent idiopathic scoliosis (AIS) by three-dimensional (3D) image reconstruction using biplanar stereoradiography (EOS) (EOS Imaging, Paris, France) and identify factors associated with postoperative pulmonary function deterioration (PFD). A total of 67 patients with Lenke type 1 or 2 AIS (59 females and 8 males; mean age, 14.4 years) undergoing posterior corrective fusion with a rod rotation maneuver based on segmental pedicle screw fixation were recruited. 3D images and pulmonary function test results were analyzed preoperatively and at 2 years postoperatively. The following parameters were measured: maximum thickness, maximum width, thoracic index, rib hump, rib cage volume (RCV), spinal penetration index (SPI), endothoracic hump ratio (EHR), vertebra-sternum angle (VSA), rib-vertebra angle difference, vertebral lateral decentering (VLD), forced vital capacity (FVC), and percent predicted FVC (%FVC). PFD was defined as a postoperative %FVC decline of 5% or greater. Patients were divided into two groups, namely PFD and non-PFD. FVC increased from 2.62 L to 2.73 L, while %FVC decreased from 88.7% to 82.7%. The maximum width diminished postoperatively in the PFD group. Patients in the PFD group exhibited a significantly smaller increase in RCV and VLD as well as a significantly smaller decrease in SPI, EHR, and VSA than those in the non-PFD group. The rib cage parameters quantified on 3D images reconstructed using EOS are useful in identifying factors affecting PFD in patients with AIS.

Reference equations for pulmonary diffusing capacity using segmented regression show similar predictive accuracy as GAMLSS models

Purpose

To determine whether generalised additive models of location, scale and shape (GAMLSS) developed for pulmonary diffusing capacity are superior to segmented (piecewise) regression models, and to update reference equations for pulmonary diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO), which may be affected by the equipment used for its measurement.

Methods

Data were pooled from five studies that developed reference equations for DLCO and DLNO (n=530 F/546 M; 5–95 years old, body mass index 12.4–39.0 kg/m²). Reference equations were created for DLCO and DLNO using both GAMLSS and segmented linear regression. Cross-validation was applied to compare the prediction accuracy of the two models as follows: 80% of the pooled data were used to create the equations, and the remaining 20% was used to examine the fit. This was repeated 100 times. Then, the root-mean-square error was compared between both models.

Results

In males, GAMLSS models were 7% worse to 3% better compared to segmented regression for DLCO and DLNO. In females, GAMLSS models were 2% worse to 5% better compared to segmented linear regression for DLCO and DLNO. The Hyp'Air Compact measured DLNO and alveolar volume (VA) that was approximately 16–20 mL/min/mm Hg and 0.2–0.4 L higher, respectively, compared to the Jaeger MasterScreen Pro. The measured DLCO was similar between devices after controlling for altitude.

Conclusions

For the development of pulmonary function reference equations, we propose that segmented linear regression can be used instead of GAMLSS due to its simplicity, especially when the predictive accuracy is similar between the two models, overall.

Protracted respiratory findings in children post-SARS-CoV-2 infection

INTRODUCTION

Although prolonged respiratory symptoms following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection have been described in adults, data are emerging that children also experience long-term sequelae of coronavirus disease 2019 (COVID-19). The respiratory sequelae of COVID-19 in children remain poorly characterized. In this study we describe health data and respiratory findings in pediatric patients presenting with persistent respiratory symptoms following COVID-19.

METHODS

This study included patients referred to Pulmonary Clinic at the Children's Hospital of Philadelphia between December 2020 and April 2021 (n = 29). Inclusion criteria included a history of SARS-CoV-2 RNA positivity or confirmed close household contact and suggestive symptoms. A retrospective chart review was performed and demographic, clinical, imaging, and functional test data were collected.

RESULTS

The mean age at presentation to clinic was 13.1 years (range: 4-19 years). Patients had persistent respiratory symptoms ranging from 1.3 to 6.7 months postacute infection. Persistent dyspnea and/or exertional dyspnea were present in nearly all (96.6%) patients at the time of clinic presentation. Other reported chronic symptoms included cough (51.7%) and exercise intolerance (48.3%). Fatigue was reported in 13.8% of subjects. Many subjects were overweight or obese (62.1%) and 11 subjects (37.9%) had a prior history of asthma. Spirometry and plethysmography were normal in most patients. The six-minute walk test (6MWT) revealed exercise intolerance and significant tachycardia in two-thirds of the nine children tested.

CONCLUSION

Exertional dyspnea, cough and exercise intolerance were the most common respiratory symptoms in children with postacute COVID-19 respiratory symptoms seen in an outpatient pulmonary clinic. Spirometry (and plethysmography when available), however, was mostly normal, and exertional intolerance was frequently demonstrated using the 6MWT.

Molecular crosstalk in tracheal development and its recurrence in adult tissue regeneration

The trachea is a rigid air duct with some mobility, which comprises the upper region of the respiratory tract and delivers inhaled air to alveoli for gas exchange. During development, the tracheal primordium is first established at the ventral anterior foregut by interactions between the epithelium and mesenchyme through various signaling pathways, such as Wnt, Bmp, retinoic acid, Shh, and Fgf, and then segregates from digestive organs. Abnormalities in this crosstalk result in lethal congenital diseases, such as tracheal agenesis. Interestingly, these molecular mechanisms also play roles in tissue regeneration in adulthood, although it remains less understood compared with their roles in embryonic development. In this review, we discuss cellular and molecular mechanisms of trachea development that regulate the morphogenesis of this simple tubular structure and identities of individual differentiated cells. We also discuss how the facultative regeneration capacity of the epithelium is established during development and maintained in adulthood.

Uncontrolled asthma from childhood to young adulthood associates with airflow obstruction

Introduction

Lung function development from childhood to young adulthood is important for lung health later in life. We investigated the association between asthma control and lung function from 8 to 24 years of age.

Methods

A total of 668 participants from the population-based BAMSE cohort study, with persistent or incidental asthma and between 8 and 24 years of age, were included. Asthma was defined as controlled or uncontrolled at each examination based on the Global Initiative for Asthma (GINA) criteria. Dynamic spirometry was performed at 8, 16 and 24 years of age. Associations between uncontrolled asthma and pre-bronchodilation forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC) and FEV₁/FVC ratio were evaluated with a generalised estimating equation model, as overall associations and at each examination. Unadjusted and adjusted (for sex, current asthma, allergic sensitisation, body mass index, smoking, smoke exposure, inhaled corticosteroid use) analyses were done; and were thereafter stratified by sex, elevated blood eosinophils (≥0.3×10⁹ cells·µL⁻¹), elevated F_ENO (≥25 ppb), allergic sensitisation and ever/never smoking.

Results

Uncontrolled asthma was associated with a lower overall FEV₁/FVC z-score from 8 to 24 years of age (adjusted regression coefficient −0.11; 95% CI (−0.20 to −0.02; p=0.016). After stratification, this association was primarily seen among females (adjusted regression coefficient −0.170; 95% CI (−0.298 to −0.044; p=0.009) and participants with elevated F_ENO (regression coefficient −0.207; 95% CI −0.342 to −0.073; p=0.002), in contrast to males and participants with normal F_ENO.

Conclusion

Uncontrolled asthma is associated with airflow obstruction from childhood to young adulthood. This highlights the importance of active management of asthma during growth.

Uncontrolled asthma from 8 to 24 years of age is associated with a lower overall FEV₁/FVC z-score. Intensified treatment of symptomatic asthma, especially asthma with elevated F_ENO and in females, could have important implications for future lung health.https://bit.ly/3pHkleN