Reference ranges for spirometry across all ages: a new approach

Diffusion kurtosis and quantitative susceptibility mapping MRI are sensitive to structural abnormalities in amyotrophic lateral sclerosis

Objective

To construct a clinical diagnostic biomarker using state-of-the-art microstructural MRI in the motor cortex of people with amyotrophic lateral sclerosis (ALS).

Methods

Clinical and MRI data were obtained from 21 ALS patients (aged 54 ± 14 years, 33% female) and 63 age- and gender-matched controls (aged 48 ± 18 years, 43% female). MRI was acquired at 3T and included T1-weighted scan (for volumetrics), arterial spin labelling (for cerebral blood flow), susceptibility-weighted angiography (for iron deposition) and multiband diffusion kurtosis imaging (for tissue microstructure). Group differences in imaging measures in the motor cortex were tested by general linear model and relationships to clinical variables by linear regression.

Results

The ALS group had mild-to-moderate impairment (disease duration: 1.8 ± 0.8 years; ALS functional rating scale 40.2 ± 6.0; forced vital capacity 83% ± 22%). No age or gender differences were present between groups. We found significant group differences in diffusion kurtosis metrics (apparent, mean, radial and axial kurtosis: p < .01) and iron deposition in the motor cortex (p = .03). Within the ALS group, we found significant relationships between motor cortex volume, apparent diffusion and disease duration (adjusted R² = 0.27, p = .011); and between the apparent and radial kurtosis metrics and ALS functional rating scale (adjusted R² = 0.25, p = .033). A composite imaging biomarker comprising kurtosis and iron deposition measures yielded a maximal diagnostic accuracy of 83% (81% sensitivity, 85% specificity) and an area-under-the-curve of 0.86.

Conclusion

Diffusion kurtosis is sensitive to early changes present in the motor region in ALS. We propose a composite imaging biomarker reflecting tissue microstructural changes in early ALS that may provide clinically valuable diagnostic information.

•

A biomarker based on diffusion kurtosis imaging achieved an accuracy of 83%.

•

Kurtosis-based measures were more abnormal in ALS than tensor-based measures.

•

Motor cortex in the symptomatic hemisphere was smaller and had greater iron concentration.

•

There was a 1 mL volume loss per year in ALS motor cortex.

Effects of elastic band resistance exercises with breathing techniques on pulmonary function in female seniors

The purpose of this study was to investigate the effects of elastic-band resistance exercises combined with breathing techniques on pulmonary function in female seniors. Forty-five female seniors 65 years or older were recruited from a welfare center and assigned to an experimental (n=23) or control (n=22) group. The experimental group used an elastic band with a resistance exercises while concurrently using specific breathing techniques. The control group conducted the same resistance tasks without the respiration exercises. Respiratory function data were collected before and after the 6-week intervention. The experimental group showed a significant increase in forced vital capacity (FVC), forced expiratory volume 1 sec (FEV₁), and in FEV₁ as a percentage of FVC. In addition, there were significant differences in the FVC and FEV₁ levels between groups. The results show that resistance accompanied by breathing techniques positively affects senior respiratory function when an elastic band is used for exercise.

Weighing the evidence for pharmacological treatment interventions in mild COPD; a narrative perspective

There is increasing focus on understanding the nature of chronic obstructive pulmonary disease (COPD) during the earlier stages. Mild COPD (Global Initiative for Chronic Obstructive Lung Disease [GOLD] stage 1 or the now-withdrawn GOLD stage 0) represents an early stage of COPD that may progress to more severe disease. This review summarises the disease burden of patients with mild COPD and discusses the evidence for treatment intervention in this subgroup.

Overall, patients with mild COPD suffer a substantial disease burden that includes persistent or potentially debilitating symptoms, increased risk of exacerbations, increased healthcare utilisation, reduced exercise tolerance and physical activity, and a higher rate of lung function decline versus controls. However, the evidence for treatment efficacy in these patients is limited due to their frequent exclusion from clinical trials. Careful assessment of disease burden and the rate of disease progression in individual patients, rather than a reliance on spirometry data, may identify patients who could benefit from earlier treatment intervention.

Development and validation of models to predict respiratory function in persons with long-term spinal cord injury

STUDY DESIGN

Multicenter, cross-sectional study.

OBJECTIVES

To validate previously developed respiratory function prediction models for persons with long-term spinal cord injury (SCI) and if necessary develop and validate new models.

SETTING

Ten SCI rehabilitation centers.

METHODS

Five respiratory function parameters were measured in adults with chronic, traumatic, motor complete SCI (C4-T12). First, the models published in 2012 were validated using Bland-Altman plots. Then, new models were calculated using 80% of the dataset by multiple regression analysis with the candidate predictors gender, age, height, weight, time post injury (TPI), lesion level, and smoking. In a third step, the new models were validated using the other 20% of the dataset by Bland-Altman plots.

RESULTS

In total 613 participants were included. For persons with long-term SCI, the 2012 models were poorly predictive, especially for respiratory muscle strength (R2 = 0.4). Significant predictors for all respiratory function parameters in the new models (R2 = 0.7-0.8) were lesion level, gender and weight. Small effects on single outcome parameters were observed for TPI and age whereas smoking had no effect. For the new models the mean differences between measured and predicted values for respiratory muscle strength were 4.0 ± 36.0 cm H₂O and for lung function parameters -0.5 ± 1.2 L (FVC), -0.3 ± 0.9 L (FEV1) and -0.5 ± 2.0 L/s (PEF).

CONCLUSION

We did not find better models for lung function in long-term SCI but those for respiratory muscle strength showed better accuracy.

SPONSORSHIP

The content of this publication was developed under grant from Wings for Life, grant number WFL-CH-017/14.

Assessment of lung function in successfully treated tuberculosis reveals high burden of ventilatory defects and COPD

Background

Burden, phenotype and risk-factors of lung function defects in successfully treated tuberculosis cases are unclear.

Methods

We performed spirometry with bronchodilators in new drug-sensitive adult (≥18 years) pulmonary tuberculosis cases during the 12 months following successful treatment in India. Airflow obstruction was defined as pre-bronchodilator FEV1/FVC<5^th percentile of Global Lung Initiative mixed-ethnicity reference (lower limit of normal [LLN]). Chronic obstructive pulmonary disease (COPD) was defined as post-bronchodilator FEV1/FVC<LLN among participants with obstruction. Restrictive spirometry pattern was defined as FVC<LLN among participants without obstruction. Multivariable logistic and linear regression was used to identify risk-factors for obstruction, restriction and low lung function despite successful treatment.

Results

Of the 172 participants included in the analysis, 82 (48%) were female, 22 (13%) had diabetes and 34 (20%) ever-smoked with a median (IQR) exposure of 3.5 (0.2–9.9) pack-years. Median (IQR) age and body-mass index (BMI) at enrollment was 32 (23–39) years and 18.1 (16.0–20.5) kg/m² respectively. Airflow obstruction was detected in 42 (24%) participants; of whom 9 (21%) responded to short-acting bronchodilators and 25 (56%) had COPD; and was associated with duration of illness prior to treatment (aOR = 1.32 per 30-days, 95%CI 1.04–1.68, p = 0.02). A restrictive spirometry pattern was detected in 89 (52%) participants and was associated with female sex (aOR = 3.73, 95%CI 1.51–9.17, p = 0.004) and diabetes (aOR = 4.06, 95%CI 1.14–14.42, p = 0.03). Higher HbA1c at treatment initiation was associated with greater odds of a restrictive spirometry pattern (aOR = 1.29 per unit higher HbA1c, 95%CI 1.04 to 1.60, p = 0.02).

Conclusion

We found a high burden of lung function defects and COPD in tuberculosis cases who successfully completed treatment. Screening for chronic lung diseases following treatment and linkage to respiratory health clinics should be included in the routine management plan of all tuberculosis cases in India, regardless of conventional COPD risk-factors such as older age and smoking.

Asthma medication in children who are overweight/obese: justified treatment?

BACKGROUND

The prevalence of asthma and obesity have increased over the last decades. A possible association between these two chronic illnesses has been suggested, since the prevalence of asthmatic symptoms rises with increasing Body Mass Index (BMI). However, asthma is only one of several possible causes of shortness of breath in obese children. The aim of this study is to evaluate the prevalence of overtreatment with asthma medication in a cohort overweight/obese children with respiratory symptoms visiting a pediatric outpatient clinic.

METHODS

Children referred to a pediatric outpatient clinic aged ≥4- ≤ 18 years with overweight/obesity (defined as BMI-sds > 1.1) and asthmatic symptoms were included. The diagnosis asthma was evaluated and classified in no, unlikely, probable and confirmed asthma, based on clinical parameters and/or spirometry results. Overtreatment was defined as asthma medication prescribed in participants classified as no or unlikely asthma. And undertreatment as probable or confirmed asthma without asthma medication prescribed .

RESULTS

Three hundred thirty-eight participants were included, of which 92.6% (313/338) had a prescription for asthma medication. Overtreatment was observed in 27.2% (92/338) participants. Nine participants were undertreated.

CONCLUSION

More than 25% overtreatment with asthma medication was observed in a cohort overweight/obese children with asthmatic symptoms. This finding emphasizes that the diagnosis of asthma must be confirmed before commencement of medication. The diagnosis of asthma should be based on standard questionnaires evaluating asthmatic symptoms, lung functions test and regular reassessments. Further studies concerning overtreatment with asthma medication in normal weight pediatric populations are warranted, to evaluate whether overtreatment is specific for overweight/obese children.

Incidence and risk factors of paediatric cystic fibrosis-related diabetes

INTRODUCTION

Cystic fibrosis-related diabetes (CFRD) is a common complication of cystic fibrosis (CF) directly linked to increased morbidity and mortality. Both the incidence of type I and type II diabetes has been shown to increase in the general population. In this study, we investigated the incidence and risk factors of CFRD in a paediatric CF population.

METHODS

Prospectively collected data from the Canadian CF Registry (CCFR) from 2000 to 2016 for patients ages 10 to 18 years was used to determine the incidence of CFRD. Risk factors for CFRD in the Canadian population were investigated using a nested case-control design. Conditional logistic regression analysis with a 4:1 control: case matching was used.

RESULTS

From 2000 to 2016, 2326 patients with CF aged between 10 through 18 years were included in the CCFR, during this time the overall incidence rate of CFRD was 2.1 cases per 100 patient-years (95% confidence interval 1.8 to 2.3). Incidence rates were stable in the Canadian cohort over three consecutive time periods 2000-2005, 2006-2010; 2011-2016. Worse lung function, female gender, history of allergic bronchopulmonary aspergillosis, Gastrostomy tube insertion and liver disease were statistically significant risk factors for CFRD.

CONCLUSION

The incidence of CFRD in the Canadian paediatric population has been stable over time, in contrast to the rising rates of Type 1 and Type 2 diabetes in the general paediatric population. The risk factor for CFRD in this contemporary population were consistent with previous studies.

Re-evaluation of combination therapy in chronic obstructive pulmonary disease (COPD)

BACKGROUND

Clinical trials of COPD pharmacotherapy typically involve aging populations with moderate-to-severe COPD, but the latter is often diagnosed by spirometric criteria that are not age-appropriate across the continuum of lung function. We have therefore re-evaluated the clinical effect of combination therapy (salmeterol plus fluticasone) in moderate-to-severe COPD, using more age-appropriate spirometric criteria from the Global Lung Function Initiative (GLI) and trial data from Towards a Revolution in COPD Health (TORCH).

METHODS

Of the 6112 TORCH participants, 5688 (93.1%) had GLI-based moderate-to-severe COPD (mean age 64.8 years). The primary outcome was all-cause mortality and the primary comparison was combination therapy vs. placebo. Secondary outcomes included COPD and cardiovascular (CV) mortality and pneumonia. A modified intention-to-treat analysis evaluated differences in time-to-event over a three-year period, using Cox proportional hazards models with statistical significance at p < 0.010 (acknowledging repeated significance testing).

RESULTS

Relative to placebo, combination therapy yielded a statistically non-significant reduction in all-cause mortality-adjusted hazard ratio [adjHR] 0.78 (95% confidence interval [CI]: 0.64, 0.95), p = 0.012. Relative to placebo, combination therapy also yielded statistically non-significant reductions in COPD and CV mortality-adjHR 0.75 (95% CI: 0.55, 1.02), p = 0.068 and adjHR 0.76 (95% CI: 0.53, 1.09), p = 0.135, respectively. In contrast, combination therapy yielded a statistically significant increased risk of pneumonia, relative to placebo-adjHR 1.80 (95% CI: 1.46, 2.21), p < 0.001.

CONCLUSION

In GLI-based moderate-to-severe COPD, combination therapy yields a statistically significant increased risk of pneumonia but the reductions in mortality are not statistically significant, although could potentially be clinically meaningful.

Difference in Long-Term Trends in COPD Mortality between China and the U.S., 1992⁻2017: An Age⁻Period⁻Cohort Analysis

Complications due to chronic obstructive pulmonary disease (COPD) is a leading cause of death in China and the United States (U.S.). This study aimed to investigate the long-term trends in COPD mortality in China and the U.S. using data from the Global Burden of Disease Study 2017 (GBD 2017) and explore the age, period, and cohort effects independently by sex under the age-period-cohort (APC) framework. Taking the age group 40-44 years old, the period 1992-1996, and the birth cohort 1913-1917 as reference groups, we found that the age relative risks (RRs) of COPD mortality increased exponentially in both China and the U.S., the period RRs increased in the U.S. but decreased in China; and the cohort RRs showed an overall downward trend in both China and the U.S. with the year of birth. From 1992 to 2017, the increased RRs of COPD mortality in the U.S. was mainly attributable to the increased prevalence of smoking before 1965, while the decreased RRs of COPD mortality in China was mainly attributable to reduced air pollution as well as improvements in medical technology and more accessible health services. Reducing tobacco consumption may be the most effective and feasible way to prevent COPD in China. However, we also need to pay more attention to COPD in nonsmokers in the future.

Face Masks and Cough Etiquette Reduce the Cough Aerosol Concentration of Pseudomonas aeruginosa in People with Cystic Fibrosis

RATIONALE

People with cystic fibrosis (CF) generate Pseudomonas aeruginosa in droplet nuclei during coughing. The use of surgical masks has been recommended in healthcare settings to minimize pathogen transmission between patients with CF.

OBJECTIVES

To determine if face masks and cough etiquette reduce viable P. aeruginosa aerosolized during coughing.

METHODS

Twenty-five adults with CF and chronic P. aeruginosa infection were recruited. Participants performed six talking and coughing maneuvers, with or without face masks (surgical and N95) and hand covering the mouth when coughing (cough etiquette) in an aerosol-sampling device. An Andersen Cascade Impactor was used to sample the aerosol at 2 meters from each participant. Quantitative sputum and aerosol bacterial cultures were performed, and participants rated the mask comfort levels during the cough maneuvers.

MEASUREMENTS AND MAIN RESULTS

During uncovered coughing (reference maneuver), 19 of 25 (76%) participants produced aerosols containing P. aeruginosa, with a positive correlation found between sputum P. aeruginosa concentration (measured as cfu/ml) and aerosol P. aeruginosa colony-forming units. There was a reduction in aerosol P. aeruginosa load during coughing with a surgical mask, coughing with an N95 mask, and cough etiquette compared with uncovered coughing (P < 0.001). A similar reduction in total colony-forming units was observed for both masks during coughing; yet, participants rated the surgical masks as more comfortable (P = 0.013). Cough etiquette provided approximately half the reduction of viable aerosols of the mask interventions during voluntary coughing. Talking was a low viable aerosol-producing activity.

CONCLUSIONS

Face masks reduce cough-generated P. aeruginosa aerosols, with the surgical mask providing enhanced comfort. Cough etiquette was less effective at reducing viable aerosols.

Inferring Multidimensional Rates of Aging from Cross-Sectional Data

Modeling how individuals evolve over time is a fundamental problem in the natural and social sciences. However, existing datasets are often cross-sectional with each individual observed only once, making it impossible to apply traditional time-series methods. Motivated by the study of human aging, we present an interpretable latent-variable model that learns temporal dynamics from cross-sectional data. Our model represents each individual's features over time as a nonlinear function of a low-dimensional, linearly-evolving latent state. We prove that when this nonlinear function is constrained to be order-isomorphic, the model family is identifiable solely from cross-sectional data provided the distribution of time-independent variation is known. On the UK Biobank human health dataset, our model reconstructs the observed data while learning interpretable rates of aging associated with diseases, mortality, and aging risk factors.

Joint Indian Chest Society-National College of Chest Physicians (India) guidelines for spirometry

Although a simple and useful pulmonary function test, spirometry remains underutilized in India. The Indian Chest Society and National College of Chest Physicians (India) jointly supported an expert group to provide recommendations for spirometry in India. Based on a scientific grading of available published evidence, as well as other international recommendations, we propose a consensus statement for planning, performing and interpreting spirometry in a systematic manner across all levels of healthcare in India. We stress the use of standard equipment, and the need for quality control, to optimize testing. Important technical requirements for patient selection, and proper conduct of the vital capacity maneuver, are outlined. A brief algorithm to interpret and report spirometric data using minimal and most important variables is presented. The use of statistically valid lower limits of normality during interpretation is emphasized, and a listing of Indian reference equations is provided for this purpose. Other important issues such as peak expiratory flow, bronchodilator reversibility testing, and technician training are also discussed. We hope that this document will improve use of spirometry in a standardized fashion across diverse settings in India.

Clinical pulmonary function testing in Duchenne muscular dystrophy

In Duchenne muscular dystrophy there is a well-established progressive loss of upper and lower extremity muscle function that is evident from the earliest stages of decline and through permanent loss of function. There is not the same visible evidence of decline in respiratory muscle function decline toward respiratory failure; therefore, comprehensive pulmonary function testing provides a critical component of a comprehensive longitudinal respiratory assessment. There are multiple ways of assessing separate inspiratory and expiratory muscle function and also a summative output of each to provide broad information to help identify disease status and guide intervention as appropriate.

Transmission of bacteria in bronchiectasis and chronic obstructive pulmonary disease: Low burden of cough aerosols

BACKGROUND AND OBJECTIVE

Aerosol transmission of Pseudomonas aeruginosa has been suggested as a possible mode of respiratory infection spread in patients with cystic fibrosis (CF); however, whether this occurs in other suppurative lung diseases is unknown. Therefore, we aimed to determine if (i) patients with bronchiectasis (unrelated to CF) or chronic obstructive pulmonary disease (COPD) can aerosolize P. aeruginosa during coughing and (ii) if genetically indistinguishable (shared) P. aeruginosa strains are present in these disease cohorts.

METHODS

People with bronchiectasis or COPD and P. aeruginosa respiratory infection were recruited for two studies. Aerosol study: Participants (n = 20) underwent cough testing using validated cough rigs to determine the survival of P. aeruginosa aerosols in the air over distance and duration. Genotyping study: P. aeruginosa sputum isolates (n = 95) were genotyped using the iPLEX20SNP platform, with a subset subjected to the enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) assay to ascertain their genetic relatedness.

RESULTS

Aerosol study: Overall, 7 of 20 (35%) participants released P. aeruginosa cough aerosols during at least one of the cough aerosol tests. These cough aerosols remained viable for 4 m from the source and for 15 min after coughing. The mean total aerosol count of P. aeruginosa at 2 m was two colony-forming units. Typing study: No shared P. aeruginosa strains were identified.

CONCLUSION

Low viable count of P. aeruginosa cough aerosols and a lack of shared P. aeruginosa strains observed suggest that aerosol transmission of P. aeruginosa is an unlikely mode of respiratory infection spread in patients with bronchiectasis and COPD.

Assessment of stability and fluctuations of cultured lower airway bacterial communities in people with cystic fibrosis

BACKGROUND

Routine clinical culture detects a subset of the cystic fibrosis (CF) airways microbiota based on culture-independent (molecular) methods. This study aimed to determine how extended sputum culture of viable bacteria changes over time in relation to clinical status and predicts exacerbations.

METHODS

Sputa from patients at a baseline stable and up to three subsequent time-points were analysed by extended-quantitative culture; aerobe/anaerobe densities, ecological indexes and community structure were assessed together with clinical outcomes.

RESULTS

Eighty patients were prospectively recruited. Sputa were successfully collected and cultured at 199/267 (74.5%) study visits. Eighty-two sputa from 25 patients comprised a complete sample-set for longitudinal analyses. Bacterial density, ecological indexes and clinical outcomes were unchanged in 18 patients with three sequential stable visits. Conversely, in 7 patients who had an exacerbation, total bacterial and aerobe densities differed over four study visits (P < .001) with this difference particularly apparent between the baseline visit and completion of acute antibiotic treatment where a decrease in density was observed. Bacterial communities were more similar within than between patients but stable patients had the least variation in community structure over time. Using logistic regression in a further analysis, baseline features in 37 patients without compared to 15 patients with a subsequent exacerbation showed that clinical measures rather than bacterial density or ecological indexes were independent predictors of an exacerbation.

CONCLUSIONS

Greater fluctuation in the viable bacterial community during treatment of an exacerbation than between stable visits was observed. Extended-quantitative culture did not provide prognostic information of a future exacerbation.

Comparison of hypothesis- and data-driven asthma phenotypes in NHANES 2007-2012: the importance of comprehensive data availability

Background

Half of the adults with current asthma among the US National Health and Nutrition Examination Survey (NHANES) participants could be classified in more than one hypothesis-driven phenotype. A data-driven approach applied to the same subjects may allow a more useful classification compared to the hypothesis-driven one.

Aim

To compare previously defined hypothesis-driven with newly derived data-driven asthma phenotypes, identified by latent class analysis (LCA), in adults with current asthma from NHANES 2007–2012.

Methods

Adults (≥ 18 years) with current asthma from the NHANES were included (n = 1059). LCA included variables commonly used to subdivide asthma. LCA models were derived independently according to age groups: < 40 and ≥ 40 years old.

Results

Two data-driven phenotypes were identified among adults with current asthma, for both age groups. The proportions of the hypothesis-driven phenotypes were similar among the two data-driven phenotypes (p > 0.05). Class A < 40 years (n = 285; 75%) and Class A ≥ 40 years (n = 462; 73%), respectively, were characterized by a predominance of highly symptomatic asthma subjects with poor lung function, compared to Class B < 40 years (n = 94; 25%) and Class B ≥ 40 years (n = 170; 27%). Inflammatory biomarkers, smoking status, presence of obesity and hay fever did not markedly differ between the phenotypes.

Conclusion

Both data- and hypothesis-driven approaches using clinical and physiological variables commonly used to characterize asthma are suboptimal to identify asthma phenotypes among adults from the general population. Further studies based on more comprehensive disease features are required to identify asthma phenotypes in population-based studies.

Electronic supplementary material

The online version of this article (10.1186/s13601-019-0258-7) contains supplementary material, which is available to authorized users.

Evaluation of Indian Prediction Models for Lung Function Parameters: A Statistical Approach

BACKGROUND

Interpretation of lung function test parameters is usually based on comparisons of data with reference (predicted) values based on healthy subjects. Predicted values are obtained from studies of "normal" or "healthy" subjects with similar anthropometric and ethnic characteristics. Regression models are generally used to obtain the reference values from measurements observed in a representative sample of healthy subjects.

OBJECTIVES

The study aims to carry out a statistical evaluation of the Indian prediction models of lung function parameters and critically evaluate the reference values for the same in an Indian context.

METHODS

The screening and inclusion of the articles for the study was done using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Evaluation of the prediction models has been done with respect to modeling approach, regression diagnostics and methodology protocol. The suitability of the models has also been evaluated using a checklist comprising of 8 criteria developed using the American Thoracic Society (ATS) guidelines.

RESULTS

Using the PRISMA guidelines 32 articles with a total sample size of 25,289 subjects were included in the final synthesis. Multiple linear regression models were used in 27 articles, with one additionally using weighted least squares technique and 4 using step-wise regression method. Regression diagnostics as per the ATS guidelines were performed and reported by 22 articles. The prediction models were traditionally developed using ordinary least squares method (OLS) without examining the homoskedasticity of residuals. The quality assessment using the checklist developed revealed that only 5 articles satisfied more than 7 out of 8 criteria, and a further 8 articles satisfied less than 3 criteria of suitability of prediction models.

CONCLUSIONS

Indian prediction models for lung function models are traditionally based on linear regression models, however with more advancement in computational power for sophisticated statistical techniques, more robust prediction models are required in the Indian context.

Results of Phrenic Nerve Transfer to the Musculocutaneous Nerve Using Video-Assisted Thoracoscopy in Patients with Traumatic Brachial Plexus Injury: Series of 28 Cases

BACKGROUND

The phrenic nerve can be transferred to the musculocutaneous nerve using video-assisted thoracoscopy, aiming at the recovery of elbow flexion in patients with traumatic brachial plexus injuries. There are few scientific papers in the literature that evaluate the results of this operative technique.

OBJECTIVE

To evaluate biceps strength and pulmonary function after the transfer of the phrenic nerve to the musculocutaneous nerve using video-assisted thoracoscopy.

METHODS

A retrospective study was carried out in a sample composed of 28 patients who were victims of traumatic injury to the brachial plexus from 2008 to 2013. Muscle strength was graded using the British Medical Research Council (BMRC) scale and pulmonary function through spirometry. Statistical tests, with significance level of 5%, were used.

RESULTS

In total, 74.1% of the patients had biceps strength greater than or equal to M3. All patients had a decrease in forced vital capacity and forced expiratory volume in 1 s, with no evidence of recovery over time.

CONCLUSION

Transferring the phrenic nerve to the musculocutaneous nerve using video-assisted thoracoscopy may lead to an increase in biceps strength to BMRC M3 or greater in most patients. Considering the deterioration in the parameters of spirometry observed in our patients and the future effects of aging in the respiratory system, it is not possible at the moment to guarantee the safety of this operative technique in the long term.

Comparison of ERS'93 to the newly published GLI'17 reference values for carbon monoxide transfer factor

BACKGROUND

The new predicted values for the carbon monoxide transfer factor (TL,CO) for Caucasians by the Global Lung Function Initiative are available since September 2017. Several authors have previously shown that the predicted values of Cotes et al. (ERS'93), overestimated TL,CO. However, the GLI'17 authors omitted to compare their predicted values with the ERS'93 equations, still in use throughout Europe. We present the differences between the two sets of predicted values, and in an attempt to improve the readability, used the contour plots instead of the classical 2-dimensional representations.

METHODS

Predicted values were computed for males and females for ages between 18 and 70 years and heights between 155 and 180 cm using Matlab software with increments of one unit (1 yr, 1 cm).

RESULTS

We demonstrate that GLI-'17 predicted values of TL,CO are systematically lower than those of ERS-'93, but also that the magnitude of the differences varies according to age, height and sex. More specifically, differences increase in both males and females by decreasing age and height, reaching up to 16% in males and 24% in females.

CONCLUSION

The predicted values of TL,CO by Cotes at al. are systematically larger than the new GLI'17 values. Plotting all the possible differences between predicted variables using contour graphs allows to identify the groups of subjects in whom significant changes in their predicted values will occur. Our findings should prompt physicians to investigate how switching to GLI-17 equations affects the clinical interpretation of TL,CO measurements in a real-live setting.

Evaluation of Food Insecurity in Adults and Children With Cystic Fibrosis: Community Case Study

Advances in the care and treatment of cystic fibrosis (CF) have led to improved mortality rates; therefore, considerably more individuals with CF are living into adulthood. With an increased number of CF patients advancing into adulthood, there is the need for more research that surrounds the aging adult CF patient. It is important to conduct research and collect results on the aging CF population to help better prepare the CF patient, who is dealing with the heavy treatment and financial burden of their disease, build autonomy and increase their quality of life. Of note, research has found that social, behavioral, and physical factors influence the ability of those with CF to follow dietary recommendations. A primary treatment goal in CF is a high calorie, high protein, and high fat diet. A socio-economic factor that has not been adequately investigated with regards to dietary compliance of individuals with CF is food insecurity. The aim of this community case study was to document the experiences and estimate the prevalence of food insecurity among CF patients residing in Idaho. The correlation between food insecurity and health outcomes (lung function and body mass index) was also examined. Participants included adult patients and parents of pediatric patients with CF. Food insecurity rates among CF patients of all ages were found to be significantly higher than that seen in the overall community; however, no specific correlation between food insecurity and body mass index (BMI) or lung function emerged. This case study highlights the need for continued research around food access issues in this patient population. The data resulting from this study shows the value of CF advocacy organizations promoting efforts to build resources and provide education around food insecurity issues.

Classical regression equations of spirometric parameters are not applicable for diagnosing spirometric abnormalities in adipotic adults

The prevalence of overweighing and obese adults (defined as “adipotic” adults), has markedly increased over the world. A remarkable increase in the adipotic population urgently needs developing the regression equations for predicting spirometric parameters (SPs), which are specifically applicable to adipotic adults. Unfortunately, however, the reliable equations suitable for adipotic adults have not been reported to date. Recently, Yamaguchi et al have proposed the quantitative method to estimate the effects of adiposity on deciding the SPs incorporating with age-specific contributions of various explanatory, independent variables such as age (A), standing height (H), body weight (BW), and fat fraction of body mass (F). Extending the method proposed by Yamaguchi et al, we attempted to elaborate the novel regression equations applicable for diagnosing the spirometric abnormality in adipotic adults. For accomplishing this purpose, never-smoking, adipotic adults with body mass index (BMI) over 25 kg/m² and no respiratory illness were recruited from the general population in Japan (n = 3696, including men: 1890 and women: 1806). Introducing the four explanatory variables of A, H, BW, and F, gender-specific and age-dependent regression equations that allowed for prescribing the SPs in adipotic adults were constructed. Comparing the results obtained for non-adipotic adults (i.e., those with normal BMI), the negative or positive impact of height on SPs was preserved in adipotic adults, as well. However, the negative impact of age on SPs was blunted in adipotic men and the positive effect of BW on SPs was impeded in adipotic men and women. The fat fraction of body mass-elicited negative impact on SPs vanished in adipotic women. These results indicate that the regression equations of SPs for adipotic adults differ significantly from those for non-adipotic adults, leading to the conclusion that the regression equations for non-adipotic adults should not be used while judging the spirometric abnormalities in adipotic adults.

Pulmonary Function Testing in Elderly Patients Treated for a Myasthenia Gravis Exacerbation

Background and Purpose

Pulmonary function testing is a standard part of care for patients admitted to hospital with a myasthenia gravis exacerbation. It may inform clinicians' decisions to intubate patients. It is known that pulmonary function declines with age in healthy adults. We studied the effect of age on pulmonary function and serious respiratory events, including intubation, in patients admitted to hospital for a myasthenia gravis exacerbation.

Methods

Single center, retrospective cohort of consecutive patients treated for a myasthenia gravis exacerbation. Demographics, pulmonary function tests (PFTs), and respiratory events requiring intubation or emergency respiratory therapy were recorded for each encounter. Relationship of PFTs to age was analyzed using age as a continuous and as a dichotomous (cut-value 70 years) variable.

Results

Forty-nine encounters from 39 patients were included. Slow vital capacity (SVC) was negatively correlated with age (R 0.46, P value .002). Maximum inspiratory pressure (MIP) and SVC were significantly reduced in elderly versus nonelderly patients (MIP-20.0 vs -30.0 cm H₂O, P value .004; SVC 16.5 vs 23.4 mL/kg, P value .013). The incidence of respiratory events did not significantly differ between elderly and nonelderly patients (χ² P value .08).

Conclusions

In patients treated for a myasthenia gravis exacerbation, pulmonary function values are significantly reduced in elderly patients compared to nonelderly patients. Despite very low SVC and MIP values most elderly patients do not require intubation however they do require intensive monitoring for serious respiratory complications.

Association of food allergy and decreased lung function in children and young adults with asthma

BACKGROUND

Food allergy (FA) appears early in the atopic march, a progression that may lead to the development of asthma. The association between FA and pulmonary function in children with and without asthma remains unknown.

OBJECTIVE

To investigate the association between FA and lung function in children with and without asthma.

METHODS

We enrolled 1,068 children as a part of a family-based FA cohort. We then categorized children as having FA by physician diagnosis, evidence of specific IgE, and typical symptoms within 2 hours of food ingestion. We categorized asthma by physician diagnosis. We used American Thoracic Society criteria for spirometry measurements. We assessed the effects of asthma classification and FA number on lung function using mixed-effect models.

RESULTS

We enrolled 1,068 children: 417 (39%) had asthma, 402 (38%) had at least 1 FA, and 162 (15%) had 2 or more FAs. Unstratified analyses found no significant association between FA number and lung function. In children with asthma, we detected statistically significant differences in predicted forced expiratory flow at 25% to 75% between children with 2 or more FAs compared with those with none (mean [SE] β = -7.5 [3.6]; P = .04). This effect lost significance after adjusting for aeroallergen sensitization. We detected no significant associations between FA number and predicted forced expiratory volume in 1 second, forced vital capacity, and ratio of forced expiratory volume in 1 second to forced vital capacity.

CONCLUSION

Having 2 or more FAs is a potential risk factor for greater small airway airflow obstruction among children with asthma, highlighting the need for close clinical follow-up and improved intervention strategies for these patients.

Change in FEV1 and Feno Measurements as Predictors of Future Asthma Outcomes in Children

BACKGROUND

Repeated measurements of spirometry and fractional exhaled nitric oxide (Feno) are recommended as part of the management of childhood asthma, but the evidence base for such recommendations is small. We tested the hypothesis that reducing spirometric indices or increasing Feno will predict poor future asthma outcomes.

METHODS

A one-stage individual patient data meta-analysis used data from seven randomized controlled trials in which Feno was used to guide asthma treatment; spirometric indices were also measured. Change in %FEV₁ and % change in Feno between baseline and 3 months were related to having poor asthma control and to having an asthma exacerbation between 3 and 6 months after baseline.

RESULTS

Data were available from 1,112 children (mean age, 12.6 years; mean %FEV₁, 94%). A 10% reduction in %FEV₁ between baseline and 3 months was associated with 28% increased odds for asthma exacerbation (95% CI, 3-58) and with 21% increased odds for having poor asthma control (95% CI, 0-45) 6 months after baseline. A 50% increase in Feno between baseline and 3 months was associated with 11% increase in odds for poor asthma control 6 months after baseline (95% CI, 0-16). Baseline Feno and %FEV₁ were not related to asthma outcomes at 3 months.

CONCLUSIONS

Repeated measurements of %FEV₁ that are typically within the "normal" range add to clinical risk assessment of future asthma outcomes in children. The role of repeated Feno measurements is less certain because large changes were associated with small changes in outcome risk.

Spirometric Reference Equations for Elderly Chinese in Jinan Aged 60-84 Years

Background:

The interpretation of spirometry varies on different reference values. Older people are usually underrepresented in published predictive values. This study aimed at developing spirometric reference equations for elderly Chinese in Jinan aged 60–84 years and to compare them to previous equations.

Methods:

The project covered all of Jinan city, and the recruitment period lasted 9 months from January 1, 2017 to September 30, 2017, 434 healthy people aged 60–84 years who had never smoked (226 females and 208 males) were recruited to undergo spirometry. Vital capacity (VC), forced VC (FVC), forced expiratory volume in 1 s (FEV₁), FEV₁/FVC, FEV₁/VC, FEV₆, peak expiratory flow, and forced expiratory flow at 25%, 50%, 75%, and 25–75% of FVC exhaled (FEF_25%, FEF_50%, FEF_75%, and FEF_25–75%) were analyzed. Reference equations for mean and the lower limit of normal (LLN) were derived using the lambda-mu-sigma method. Comparisons between new and previous equations were performed by paired t-test.

Results:

New reference equations were developed from the sample. The LLN of FEV₁/FVC, FEF_25–75% computed using the 2012-Global Lung Function Initiative (GLI) and 2006-Hong Kong equations were both lower than the new equations. The biggest degree of difference for FEV₁/FVC was 19% (70.46% vs. 59.29%, t = 33.954, P < 0.01) and for maximal midexpiratory flow (MMEF, equals to FEF_25–75%) was 22% (0.82 vs. 0.67, t = 21.303, P < 0.01). The 1990-North China and 2009-North China equations predicted higher mean values of FEV₁/FVC and FEF_25–75% than the present model. The biggest degrees of difference were −4% (78.31% vs. 81.27%, t = −85.359, P < 0.01) and −60% (2.11 vs. 4.68, t = −170.287, P < 0.01), respectively.

Conclusions:

The newly developed spirometric reference equations are applicable to elderly Chinese in Jinan. The 2012-GLI and 2006-Hong Kong equations may lead to missed diagnoses of obstructive ventilatory defects and the small airway dysfunction, while traditional linear equations for all ages may lead to overdiagnosis.

The multi-ethnic global lung initiative 2012 (GLI-2012) norms reflect contemporary adult's Algerian spirometry

Background

The validation of the multi-ethnic GLI-2012 spirometric norms has been debated in several countries. However, its applicability in Algeria has not been verified.

Aim

To ascertain how well the GLI-2012 norms fit contemporary adult Algerian spirometric data.

Methods

This was a cross-sectional study of a convenience sample of 300 healthy non-smoker adults (50% men, age range: 18–85 years) recruited from the Algiers region general population. All participants underwent a clinical examination and a plethysmography measurement. Z-scores for some spirometric data [FEV₁, FVC, FEV₁/FVC and forced expiratory flow at 25–75% of FVC (FEF_25-75%)] were calculated. If the average Z-score deviated by “< ± 0.5” from the overall mean, the GLI-2012 norms would be considered as reflective of contemporary Algerian spirometry.

Results

The means±SDs of age, height, weight, FVC, FEV₁, FEV₁/FVC and FEF_25-75% of the participants were, respectively, 48±17 years, 1.65±0.10 m, 73±14 kg, 4.04±1.04 L, 3.18±0.82 L, 0.79±0.05 and 4.09±1.09 L/s. Almost the quarter of participants were obese. The total sample means±SDs Z-scores were 0.22±0.87 for FVC, 0.04±0.88 for FEV₁, -0.34±0.67 for FEV₁/FVC and 0.93±0.79 for FEF_25-75%. For men and women, only the means±SDs of the FEF_25-75% Z-scores exceeded the threshold of “± 0.5”, respectively, 1.13±0.77 and 0.73±0.76.

Conclusion

Results of the present study, performed in an Algerian population of healthy non-smoking adults, supported the applicability of the GLI-2012 norms to interpret FEV₁, FVC and FEV₁/FVC but not the FEF_25-75%.

Spirometric Values of Greek People and Comparison with ECSC and GLI Values in COPD People

Background:

During the past few years, the use of criteria introduced by Global Initiative for Chronic Obstructive Lung Disease (GOLD) is recommended for the diagnosis and classification of Chronic Obstructive Pulmonary Disease(COPD),taking into account the values of a Forced Expiratory Volume In 1 second (FEV1) and a Forced Expiratory Volume In 1 second (FEV1) to Forced Vital Capacity (FVC) ratio. In Europe, the reference values of the European Coal and Steel Community (ECSC), that were originally developed in 1993 are still used.

Aim of the Study:

The study aimed to carry out measurement of spirometric values in a healthy, non smoking Greek population, development of local equations and comparison with ECSC and Global Lung Initiative(GLI) equations, in order to see if there is a need for separate ones in everyday use.

Methods:

Normal predicted values for FEV1 and FEV1/FVC% were obtained from a group of 500 healthy subjects, aged 18-89 years. In addition, a group of 124 COPD patients, with no other comorbidities was studied. Patients were classified according to GOLD criteria in four groups with ECSC, GLI predicted values or with our own predicted values.

Results:

The statistical analysis has revealed that there is no significant difference among the three sets of predicted values and no statistical difference was detected among the classification of COPD patients.

Conclusion:

It is shown that the 3 sets of predicted values are almost identical, despite the fact that they have been collected from different study populations.Αccording to the study, there is no need in recalculating values for Greek population.

Exhaled NO reference limits in a large population-based sample using the Lambda-Mu-Sigma method

Absolute values are used in the interpretation of the fraction of exhaled nitric oxide (FeNO), but it has been suggested that equations to calculate reference values may be a practical and clinically useful approach. We hypothesize that the application of the Lambda-Mu-Sigma (LMS) method may improve FeNO reference equations and their interpretation. Our aims were to develop FeNO reference equations with the LMS method and to describe the difference between this method and the absolute fixed cut-offs of the current recommendations. We utilized the United States National Health and Nutrition Examination Surveys 2007-2012 and included healthy individuals with no respiratory diseases and blood eosinophils <300/mm³ ( n = 8,340). Natural log-transformed FeNO was modeled using the LMS method, imbedded in the generalized additive models for location, scale, and shape models. A set of FeNO reference equations was developed. The explanatory variables were sex, age, height, smoking habits, and race/ethnicity. A significant proportion of individuals with normal FeNO given by the equations were classified as having intermediate levels by the current recommendations. Further lower predicted FeNO compared with previous linear models was seen. In conclusion, we suggest a novel model for the prediction of reference FeNO values that can contribute to the interpretation of FeNO in clinical practice. This approach should be further validated in large samples with an objective measurement of atopy and a medical diagnosis of asthma and rhinitis. NEW & NOTEWORTHY Novel reference equations and fraction of exhaled nitric oxide (FeNO)-predicted values to improve interpretation of FeNO in clinical practice are presented. These may increase the accuracy of ruling out airway inflammation in patients with asthma or suspected asthma.

Reference values for lung function screening in 10- to 81-year-old, healthy, never-smoking residents of Southeast China

No official spirometry reference values for Chinese are available.To establish new Chinese reference values and prediction equations for lung parameters in Chinese individuals of 10 to 81 years of age.Pulmonary functions were measured according to the American Thoracic Society criteria in 1457 subjects from the Zhejiang coastal province (China). The subjects were 10 to 81 years of age, nonsmokers, and without chronic or acute diseases. Multiple stepwise linear regression analysis was performed for each parameter against age, height, weight, and body mass index (BMI; kg/m) for males and females separately.Most lung function variables were nonlinear with age and showed a plateau in younger adults, with a decline after 31 to 35 years. All spirometric data of men were higher than those of women except breathing frequency and forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC). All measured lung function parameters were strongly correlated to age, height, weight, and BMI. The highest correlation being to height in both men and women except for tidal volume and expiratory reserve volume among women. Based on previous studies, Caucasians men from the USA and Switzerland had higher FVC and FEV1 than in the present study, but only slightly higher than American blacks, British, Pakistani, and Singapore; an inverse trend was observed for Malay and Indians. Similar relationships were observed for women. The relationship between height and lung function parameters was nonlinear, with the variance of lung function parameters increasing with increasing height. For each sex, the z scores differed significantly by BMI (P < .001).This study provides spirometry equations that can be used for Chinese individuals.

Respiratory Diagnostic Tools in Neuromuscular Disease

Children with neuromuscular disease (NMD) are at risk of acquiring respiratory complications. Both clinical assessments and respiratory diagnostic tests are important to optimize the respiratory health and care of such children. The following respiratory diagnostic tools and their utility for evaluating children with NMD are discussed in this article: lung function testing (spirometry and lung volumes), peak cough flow (PCF), respiratory muscle strength testing, oximetry, capnography, and polysomnography.

Global lung function initiative 2012 reference values for spirometry in Asian Americans

Background

Spirometry reference values specifically designed for Asian Americans are currently unavailable. The performance of Global Lung Function Initiative 2012 (GLI-2012) equations on assessing spirometry in Asian Americans has not been evaluated. This study aimed to assess the fitness of relevant GLI-2012 equations for spirometry in Asian Americans.

Methods

Asian subjects who never smoked and had qualified spirometry data were extracted from the National Health and Nutrition Examination Survey (NHANES) 2011–2012. Z-scores of forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), and FEV₁/FVC were separately constructed with GLI-2012 equations for North East (NE) Asians, South East (SE) Asians, and individuals of mixed ethnic origin (Mixed). In addition, Proportions of subjects with observed spirometry data below the lower limit of normal (LLN) were also evaluated on each GLI-2012 equation of interest.

Results

This study included 567 subjects (250 men and 317 women) aged 6–79 years. Spirometry z-scores (z-FEV₁, z-FVC, and z-FEV₁/FVC) based on GLI-2012 Mixed equations had mean values close to zero (− 0.278 to − 0.057) and standard deviations close to one (1.001 to 1.128); additionally, 6.0% (95% confidence interval (CI) 3.1–8.9%) and 6.4% (95% CI 3.7–9.1%) of subjects were with observed data below LLN for FEV₁/FVC in men and women, respectively. In contrast, for NE Asian equations, all mean values of z-FEV₁ and z-FVC were smaller than − 0.5; for SE Asian equations, mean values of z-FEV₁/FVC were significantly smaller than zero in men (− 0.333) and women (− 0.440).

Conclusions

GLI-2012 equations for individuals of mixed ethnic origin adequately fitted spirometry data in this sample of Asian Americans. Future studies with larger sample sizes are needed to confirm these findings.

Electronic supplementary material

The online version of this article (10.1186/s12890-018-0658-9) contains supplementary material, which is available to authorized users.

Aging-related trajectories of lung function in the general population-The Doetinchem Cohort Study

The objective of this study was to explore trajectories of lung function decline with age in the general population, and to study the effect of sociodemographic and life style related risk factors, in particular smoking and BMI. For this purpose, we used data from the Doetinchem Cohort Study (DCS) of men and women, selected randomly from the general population and aged 20–59 years at inclusion in 1987–1991, and followed until the present. Participants in the DCS are assessed every five years. Spirometry has been performed as part of this assessment from 1994 onwards. Participants were included in this study if spirometric measurement of FEV₁, which in this study was the main parameter of interest, was acceptable and reproducible on at least one measurement round, leading to the inclusion of 5727 individuals (3008 females). Statistical analysis revealed three typical trajectories. The majority of participants followed a trajectory that closely adhered to the Global Lung Initiative Reference values (94.9% of men and 96.4% of women). Two other trajectories showed a more pronounced decline. Smoking and the presence of respiratory complaints were the best predictors of a trajectory with stronger decline. A greater BMI over the follow-up period was associated with a more unfavorable FEV₁ course both in men (β = -0.027 (SD = 0.002); P < 0.001) and in women (β = -0.008 (SD = 0.001); P < 0.001). Smokers at baseline who quit the habit during follow-up, showed smaller decline in FEV₁ in comparison to persistent smokers, independent of BMI change (In men β = -0.074 (SD = 0.020); P < 0.001. In women β = -0.277 (SD = 0.068); P < 0.001). In conclusion, three typical trajectories of age-related FEV1 decline could be distinguished. Change in the lifestyle related risk factors, BMI and smoking, significantly impact aging-related decline of lung function. Identifying deviant trajectories may help in early recognition of those at risk of a diagnosis of lung disease later in life.

Prevalence and determinants of airflow limitation in urban and rural children exposed to cooking fuels in South-East Nigeria

Background Biofuels and other cooking fuels are used in households in low- and middle-income countries. Aim To investigate the impact of cooking fuels on lung function in children in urban and rural households in South-East Nigeria. Methods The multi-stage sampling method was used to enroll children exposed to cooking fuel in the communities. Lung function values FEV1, FVC and the FEV1/FVC ratio, were measured with ndd EasyOne^R spirometer. Airflow limitation was determined with FEV1/FVC Z-score values at -1.64 as the lower limit of normal (LLN5). The Global Lung Function Initiative 2012 software was used to calculate the lung function indices. Results The median age (range) of the 912 children enrolled was 10.6 years (6-18). Altogether, 468 (51.6%) children lived in rural areas. Seven hundred and thirty-seven (80.7%) were directly exposed to cooking fuels (418/737, 56.5% in rural areas). Wood and kerosene were the dominant fuels in rural and urban households. The respective mean Z-scores of the exposed children in rural and urban were zFEV1 -0.62, FVC -0.21, FEV1/FVC -0.83 and zFEV1 -0.57, zFVC -0.14, FEV1/FVC -0.75. Few (5.2%, 38/737) of the children had airflow limitation. Most of them (60.5%, 25/38) lived in the rural community; the lowest FEV1/FVC Z-scores were those of exposed to a combination of fuels. Conclusion Exposure to cooking fuels affects lung function in children with airway limitation in a small proportion, Control measures are advocated to reduce the morbidity related to cooking fuels exposure.

Does Size Matter When Calculating the "Correct" Tidal Volume for Pediatric Mechanical Ventilation?: A Hypothesis Based on FVC

BACKGROUND

Tidal volumes standardized to predicted body weight are recommended for adult mechanical ventilation, but children are frequently ventilated by using measured body weight. The goal of this study was to examine the difference in FVC (in milliliters per kilogram [mL/kg]) by using measured body weight compared with predicted body weight in children.

METHODS

This retrospective analysis included outpatient pulmonary function tests (PFTs) from two datasets. Dataset one included 6- to 19-year-old patients undergoing PFTs from the nationally representative Canadian Health Measures Survey. Dataset two included 6- to 20-year-old patients undergoing PFTs at a freestanding children's hospital. FVC mL/kg values were analyzed against BMI z scores to show changes in FVC vs BMI between measured and predicted weight.

RESULTS

Dataset one included 5,394 PFTs from the Canadian survey. FVC from measured weight decreased as the BMI z score group increased. The median FVC from measured weight was 81.4 mL/kg in the lowest BMI z score group and 51.7 mL/kg in the highest BMI z score group. FVC from predicted weight increased slightly with increasing BMI z score group. Dataset two included 8,472 patient PFTs from clinical measurement. A decline in median FVC from measured weight (from 69.4 to 37.6 mL/kg) as BMI z score group increased was also seen.

CONCLUSIONS

FVC differs significantly when standardizing to measured weight vs predicted weight. Obese children have lung volumes reflecting their predicted body weight from height. Children with low or normal BMI have lung volumes reflecting measured body weight. These findings suggest that targeting tidal volume by using the lower of measured and predicted body weights would be the most lung-protective strategy.

Clinical impact of the lower limit of normal of FEV1/FVC on detecting chronic obstructive pulmonary disease: A follow-up study based on cross-sectional data

BACKGROUND

Criteria of obstruction that establish a diagnosis of COPD have been debated in recent years. We carried out a follow-up study to assess the impact of the new LLN reference equation for Chinese on detecting COPD compared with the traditional 0.7fixed criteria.

METHODS

We examined the prevalence and characteristics of airflow limitation for a non-child population using post-bronchodilator airflow with both age-dependent predicted lower limit of the normal value and fixed-ratio spirometric criterion. Questionnaires and spirometry were completed for all eligible subjects during the baseline examination. Participants with inconsistent diagnosis according to the two criteria, normal participants (controls) and COPD patients in stages I or II, were invited to take a cardiopulmonary exercise testing (CPET) examination and follow up for 2-4 years.

RESULTS

A total of 5448 (mean age 50.51 ± 13.2 yr) study subjects with acceptable spirometry and complete questionnaire data were included in our final analyses. COPD detection based on LLN was consistent with the GOLD 0.7 fixed-ratio in general, as 51 subjects (0.9%) were underdiagnosed, and 61 subjects (1.1%) were overdiagnosed when using LLN as the reference diagnostic criterion. The underdiagnosed subjects were younger, had more symptoms, more exposure to biofuels and worse FEV₁ than the normal group; they also demonstrated a damaged cardiopulmonary reserve capacity and significant FEV₁ decline. Except for being older, the overdiagnosed subjects differed little from the normal group.

CONCLUSIONS

Individual-dependent LLN appears to better reveal impacts on detecting airflow limitation. Participants underdiagnosed by GOLD criterion should be paid more attention.

CLINICAL TRIAL REGISTRATION

ChiCTR-ECS-13004110.

Reference values for spirometric variables for allegedly healthy workers

Introducción. La espirometría permite identificar de forma precoz el deterioro pulmonar en trabajadores expuestos a contaminantes laborales. No se tienen valores de referencia (VR) para variables espirométricas (VE) en trabajadores cubanos (TC).Objetivo. Obtener VR para VE en TC supuestamente sanos.Materiales y métodos. Estudio retrospectivo-analítico. Se obtuvo la capacidad vital forzada (CVF), el volumen espiratorio forzado en el primer segundo (VEF1), el cociente VEF1/CVF y la fracción de la espiración forzada al 25-75% de la CVF (FEF25-75) de 1 086 TC supuestamente sanos, no fumadores, de ambos sexos, con edades entre 20 y 65 años y atendidos en el Instituto Nacional de la Salud de los Trabajadores de La Habana, Cuba, entre 2009 y 2015. Los VR se obtuvieron para cada sexo de las funciones de regresión Y=α+β x Edad+χ x Talla+ε (Y=CVF, VEF1, VEF1/CVF, FEF25-75).Resultados. Edades avanzadas se asociaron con CVF y VEF1 disminuidos; la talla elevada se asoció con mayores CVF y VEF1; una FR construida se asoció con la edad, y la talla implicó un coeficiente r2 de determinación superior y un error menor. El comportamiento de la VE predicho con la ecuación desarrollada fue menos sesgado que el observado con otras importadas.Conclusiones. Los VR construidos localmente pueden ser más efectivos en el diagnóstico de las afecciones pulmonares de los TC.

Comparison of the fixed ratio and the Z-score of FEV1/FVC in the elderly population: a long-term mortality analysis from the Third National Health and Nutritional Examination Survey

Background and objective

Despite the ongoing intense debate on the definition of airflow limitation by spirometry in the elderly population, there have only been few studies comparing the fixed ratio and the Z-score of forced expiratory volume in 1 second (FEV₁)/forced vital capacity (FVC) in terms of long-term mortalities. In this study, we aimed to identify the proper method for accurately defining the airflow limitation in terms of long-term mortality prediction in the elderly population.

Methods

Data were collected from the Third National Health and Nutrition Examination Survey in the US. Non-Hispanic Caucasians aged 65–80 years were included. The receiver operating characteristic (ROC) curves of both methods were plotted and compared for 10-year all-cause, respiratory, and COPD mortalities.

Results

Of 1,331 subjects, the mean age was 71.7 years and 805 (60.5%) were males. For the 10-year all-cause mortality, the area under the curve (AUC) of the fixed ratio was significantly greater than that of the Z-score of FEV₁/FVC, but both showed poor prediction performance (0.633 vs 0.616, p<0.001). For the 10-year respiratory and COPD mortalities, both the fixed ratio and the Z-score of FEV₁/FVC showed comparable prediction performance with greater AUCs (0.784 vs 0.778, p=0.160, and 0.896 vs 0.896, p=0.971, respectively). Interestingly, the conventional cutoff of 0.7 in the fixed ratio was consistently higher than the optimal for the 10-year all-cause, respiratory, and COPD mortalities (0.70 vs 0.69, 0.62, and 0.61, respectively), whereas that of −1.64 in the Z-score of FEV₁/FVC was consistently lower than the optimal cutoff (−1.64 vs −1.31, −1.47, and −1.41, respectively).

Conclusion

In the elderly population, both the fixed ratio and the Z-score of FEV₁/FVC showed comparable prediction performance for the 10-year respiratory and COPD mortalities. However, the conventional cutoff of neither 0.70 in the fixed ratio nor −1.64 in the Z-score of FEV₁/FVC was optimal for predicting the long-term mortalities.

Collating Spirometry reference values in Asian children and Adolescents; puzzle out the reasons for variations

Lung function tests are essential for the diagnosis and management of different respiratory tract diseases; among them the spirometry is the gold standard technique. The accurate diagnosis, management and monitoring require proper interpretation of the results which depends upon the availability of spirometry reference data for that particular region to differentiate the diseased condition from the normal ones. Multiple studies had been done to find out their own area specific reference ranges but it is still lacking. This need was fulfilled by the Global Lung Function Initiative (GLI) in 2012, which reported the first global spirometry equation for all of the age groups. But some of the studies reported difference among GLI reference range and the measured range for that particular region. So here is the review of the reference ranges among 35,603 Asian children and adolescents from the 32 studies done specifically in Asia. The aim was to compare them with the study done by GLI team, along with these, tried to rule out the causal factor that are responsible for the variations in the reference ranges among the children and adolescents of different population. The literature was searched by using Google scholar and PubMed during the month of March up to July 2017. The review of all the articles published in Asia, specifically accounting for normal reference ranges in children and adolescent exhibit a wide variation among the reference ranges. This also suggest involvement of multiple modifiable and non-modifiable risk factors. So it's necessary to update the reference ranges for spirometry and its prediction equation as well.

Spirometric impairments, cardiovascular outcomes, and noncardiovascular death in older persons

BACKGROUND

In prior work involving older persons, the reported associations of spirometric impairments with cardiovascular outcomes may have been confounded by age-related changes in lung function. Hence, using more age-appropriate spirometric criteria from the Global Lung Function Initiative (GLI), we have evaluated the associations of spirometric impairments, specifically restrictive-pattern and airflow-obstruction, with cardiovascular death (CV-death) and hospitalization (CV-hospitalization). In these analyses, we also evaluated the competing outcome of noncardiovascular death (nonCV-death) and calculated measures of relative and absolute risk.

METHODS

Our study sample was drawn from the Cardiovascular Health Study (CHS), including 4232 community-dwelling white persons aged ≥65 years. Multivariable regression models included the following baseline predictors: GLI-defined restrictive-pattern and airflow-obstruction, age, male gender, obesity, waist circumference, current smoker status, ≥10 pack-years of smoking, hypertension, dyslipidemia, diabetes, and cardiovascular and cerebrovascular disease. Outcomes included adjudicated CV-death, CV-hospitalization, and nonCV-death, ascertained over 10 years of follow-up. Measures of association included hazard ratios (HRs), rate ratios (RRs), and average attributable fraction (AAF), each with 95% confidence intervals.

RESULTS

Restrictive-pattern and airflow-obstruction were associated with CV-death (adjusted HRs: 1.57 [1.18, 2.09] and 1.29 [1.04, 1.60]) and with nonCV-death (adjusted HRs: 2.10 [1.63, 2.69] and 1.79 [1.51, 2.12]), respectively. Airflow-obstruction, but not restrictive-pattern, was also associated with CV-hospitalization (adjusted RRs: 1.18 [1.02, 1.36] and 1.20 [0.96, 1.50], respectively). The adjusted AAFs of restrictive-pattern and airflow-obstruction were 1.68% (0.46, 3.06) and 2.35% (0.22, 4.72) for CV-death, and 3.44% (1.97, 5.08) and 7.77% (5.15, 10.60) for nonCV-death, respectively.

CONCLUSION

Assessment of GLI-defined spirometric impairments contributes to broad geriatric risk stratifications for both cardiovascular and non-cardiovascular outcomes.

Spirometric Criteria for Chronic Obstructive Pulmonary Disease in Clinical Trials of Pharmacotherapy

Clinical trials of pharmacotherapy in chronic obstructive pulmonary disease (COPD) often include older persons with moderate-to-severe airflow-obstruction, as defined by the Global Initiative for chronic Obstructive Lung Disease (GOLD). In this context, spirometric airflow-obstruction establishes COPD. Because GOLD misidentifies COPD and its severity in older persons, we set out to apply more age-appropriate spirometric criteria from the Global Lung function Initiative (GLI) in a prior clinical trial of COPD pharmacotherapy, specifically the Towards a Revolution in COPD Health (TORCH) trial - N = 6,112, mean age 65 years. In the TORCH trial, which enrolled GOLD-defined moderate COPD (26.2%, n = 1,200) and GOLD-defined severe COPD (73.8%, n = 4,511), the GLI reclassification yielded a higher frequency of severe COPD (89.6%, n = 5,474), the inclusion of restrictive-pattern (6.9%, n = 420) and, in turn, a very low frequency of moderate COPD (3.5%, n = 212). These GLI reclassification results suggest that GOLD-based enrollment criteria for the TORCH trial may have assembled a cohort that was: 1) less likely to respond to COPD pharmacotherapy, given the greater representation of severe COPD, very minor representation of moderate COPD, and inclusion of a non-obstructive spirometric impairment (restrictive-pattern); and 2) more likely to have medication-related adverse events, given the inappropriate use of COPD pharmacotherapy in misidentified COPD (restrictive-pattern). We therefore propose that future clinical trials of COPD pharmacotherapy should consider GLI criteria for defining COPD, including a greater representation of GLI-defined moderate COPD.

Association of generic health-related quality of life (EQ-5D dimensions) and inactivity with lung function in lung-healthy German adults: results from the KORA studies F4L and Age

PURPOSE

Among patients with lung disease, decreased lung function is associated with lower health-related quality of life. However, whether this association is detectable within the physiological variability of respiratory function in lung-healthy populations is unknown. We analyzed the association of each EQ-5D-3L dimension (mobility, self-care, usual activities, pain/discomfort, anxiety/depression) and self-reported physical inactivity with spirometric indices in lung-healthy adults. Modulating effects between inactivity and EQ-5D dimensions were considered.

METHODS

1132 non-smoking, apparently lung-healthy participants (48% male, aged 64 ± 12 years) from the population-based KORA F4L and Age surveys in Southern Germany were analyzed. Associations of each EQ-5D dimension and inactivity with spirometric indices serving as outcomes (forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), FEV₁/FVC, and mid-expiratory flow) were examined by linear regression, considering possible confounders. Interactions between EQ-5D dimensions (no problems/any problems) and inactivity (four categories of time spent engaging in exercise: inactive to most active) were assessed.

RESULTS

Among all participants 42% reported no problems in any EQ-5D dimension, 24% were inactive and 32% exercised > 2 h/week. After adjustment, FEV₁ was - 99 ml (95% CI - 166; - 32) and FVC was - 109 ml (95% CI - 195; - 24) lower among subjects with mobility problems. Comparable estimates were observed for usual activities. Inactivity was negatively associated with FVC (β-coefficient: - 83 ml, 95% CI - 166; 0), but showed no interactions with EQ-5D.

CONCLUSIONS

Problems with mobility or usual activities, and inactivity were associated with slightly lower spirometric parameters in lung-healthy adults, suggesting a relationship between perceived physical functioning and volumetric lung function.

Reference percentiles of FEV1 for the Canadian cystic fibrosis population: comparisons across time and countries

BACKGROUND

Forced expiratory volume in 1 s (FEV1) indicates lung health in cystic fibrosis (CF). FEV1 is commonly communicated as a per cent predicted of a healthy individual sharing the same age, sex, race and height. CF-specific reference equations are complementary and calibrate a patient's FEV1 to that of their CF peers.

OBJECTIVES

(1) To derive Canadian CF-specific FEV1 reference percentiles (FEV1%iles), (2) characterize how they have changed over time and (3) compare the Canadian FEV1%iles to those for USA and European CF populations.

METHOD

CF FEV1%iles are calculated using the Canadian CF Registry and quantile regression.

RESULTS

The Canadian FEV1%iles demonstrated better lung function in more recent time periods within Canada, especially below the 50% percentile and in males. When compared to USA and European FEV1%iles for the same time period, Canadian FEV1%iles were higher.

CONCLUSION

CF-specific FEV1%iles can provide useful information about changes in lung health. An online calculator (available at cfpercentile.

RESEARCH

sickkids.ca) makes these FEV1%iles accessible.

Reference Values for Spirometry Derived Using Lambda, Mu, Sigma (LMS) Method in Korean Adults: in Comparison with Previous References

BACKGROUND

The present study aimed to update the prediction equations for spirometry and their lower limits of normal (LLN) by using the lambda, mu, sigma (LMS) method and to compare the outcomes with the values of previous spirometric reference equations.

METHODS

Spirometric data of 10,249 healthy non-smokers (8,776 females) were extracted from the fourth and fifth versions of the Korea National Health and Nutrition Examination Survey (KNHANES IV, 2007-2009; V, 2010-2012). Reference equations were derived using the LMS method which allows modeling skewness (lambda [L]), mean (mu [M]), and coefficient of variation (sigma [S]). The outcome equations were compared with previous reference values.

RESULTS

Prediction equations were presented in the following form: predicted value = e{a + b × ln(height) + c × ln(age) + M - spline}. The new predicted values for spirometry and their LLN derived using the LMS method were shown to more accurately reflect transitions in pulmonary function in young adults than previous prediction equations derived using conventional regression analysis in 2013. There were partial discrepancies between the new reference values and the reference values from the Global Lung Function Initiative in 2012.

CONCLUSION

The results should be interpreted with caution for young adults and elderly males, particularly in terms of the LLN for forced expiratory volume in one second/forced vital capacity in elderly males. Serial spirometry follow-up, together with correlations with other clinical findings, should be emphasized in evaluating the pulmonary function of individuals. Future studies are needed to improve the accuracy of reference data and to develop continuous reference values for spirometry across all ages.