Special Libraries, October 1922

Volume 13, Issue 8https://scholarworks.sjsu.edu/sla_sl_1922/1007/thumbnail.jp

A Systematic Approach to Multiple Breath Nitrogen Washout Test Quality

Background: Accurate estimates of multiple breath washout (MBW) outcomes require correct operation of the device, appropriate distraction of the subject to ensure they breathe in a manner representative of their relaxed tidal breathing pattern, and appropriate interpretation of the acquired data. Based on available recommendations for an acceptable MBW test, we aimed to develop a protocol to systematically evaluate MBW measurements based on these criteria. Methods: 50MBWtest occasions were systematically reviewed for technical elements and whether the breathing pattern was representative of relaxed tidal breathing by an experienced MBW operator. The impact of qualitative and quantitative criteria on inter-observer agreement was assessed across eight MBW operators (n = 20 test occasions, compared using a Kappa statistic). Results: Using qualitative criteria, 46/168 trials were rejected: 16.6%were technically unacceptable and 10.7% were excluded due to inappropriate breathing pattern. Reviewer agreement was good using qualitative criteria and further improved with quantitative criteria from (κ = 0.53– 0.83%) to (κ 0.73–0.97%), but at the cost of exclusion of further test occasions in this retrospective data analysis. Conclusions: The application of the systematic review improved inter-observer agreement but did not affect reported MBW outcomes

Association of respiratory symptoms and lung function with occupation in the multinational Burden of Obstructive Lung Disease (BOLD) study

Background Chronic obstructive pulmonary disease has been associated with exposures in the workplace. We aimed to assess the association of respiratory symptoms and lung function with occupation in the Burden of Obstructive Lung Disease study. Methods We analysed cross-sectional data from 28 823 adults (≥40 years) in 34 countries. We considered 11 occupations and grouped them by likelihood of exposure to organic dusts, inorganic dusts and fumes. The association of chronic cough, chronic phlegm, wheeze, dyspnoea, forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1)/FVC with occupation was assessed, per study site, using multivariable regression. These estimates were then meta-analysed. Sensitivity analyses explored differences between sexes and gross national income. Results Overall, working in settings with potentially high exposure to dusts or fumes was associated with respiratory symptoms but not lung function differences. The most common occupation was farming. Compared to people not working in any of the 11 considered occupations, those who were farmers for ≥20 years were more likely to have chronic cough (OR 1.52, 95% CI 1.19–1.94), wheeze (OR 1.37, 95% CI 1.16–1.63) and dyspnoea (OR 1.83, 95% CI 1.53–2.20), but not lower FVC (β=0.02 L, 95% CI −0.02–0.06 L) or lower FEV1/FVC (β=0.04%, 95% CI −0.49–0.58%). Some findings differed by sex and gross national income. Conclusion At a population level, the occupational exposures considered in this study do not appear to be major determinants of differences in lung function, although they are associated with more respiratory symptoms. Because not all work settings were included in this study, respiratory surveillance should still be encouraged among high-risk dusty and fume job workers, especially in low- and middle-income countries.publishedVersio

Cohort Profile: Burden of Obstructive Lung Disease (BOLD) study

The Burden of Obstructive Lung Disease (BOLD) study was established to assess the prevalence of chronic airflow obstruction, a key characteristic of chronic obstructive pulmonary disease, and its risk factors in adults (≥40 years) from general populations across the world. The baseline study was conducted between 2003 and 2016, in 41 sites across Africa, Asia, Europe, North America, the Caribbean and Oceania, and collected high-quality pre- and post-bronchodilator spirometry from 28 828 participants. The follow-up study was conducted between 2019 and 2021, in 18 sites across Africa, Asia, Europe and the Caribbean. At baseline, there were in these sites 12 502 participants with high-quality spirometry. A total of 6452 were followed up, with 5936 completing the study core questionnaire. Of these, 4044 also provided high-quality pre- and post-bronchodilator spirometry. On both occasions, the core questionnaire covered information on respiratory symptoms, doctor diagnoses, health care use, medication use and ealth status, as well as potential risk factors. Information on occupation, environmental exposures and diet was also collected

The physiological determinants of airway hyperresponsiveness in elderly asthma

Asthma in the elderly is associated with worse outcomes when compared with asthma in younger populations. It is often underdiagnosed and undertreated, and as a result, elderly asthmatics suffer worse health outcomes from asthma. The primary aim of this thesis was to determine if asthma in the elderly is physiologically different to asthma in younger subjects. Airway hyperresponsiveness (AHR) was used as a physiological marker of asthma. Firstly, we found that the severity of AHR in older asthmatics is predicted by residual volume and peripheral airway ventilation heterogeneity. These predictors are different to those which predict the severity of AHR in younger asthmatics. Secondly, we found that the predictors of AHR severity are different in age matched asthmatics and COPD subjects, indicating that there is a disease-specific abnormality. Thirdly, we found that excessive airway closure with bronchoconstriction increases with disease duration and is predicted by baseline conducting airway ventilation heterogeneity and gas trapping. Finally, we found that increased peripheral airway ventilation heterogeneity in elderly asthmatics is related to lung volumes and not to increases in lung compliance. Thus, these studies provide strong evidence that asthma in the elderly is physiologically different to asthma in young people. Furthermore, they provide new information about the site and nature of the physiological determinants of AHR in the elderly

The physiological determinants of airway hyperresponsiveness in elderly asthma

Asthma in the elderly is associated with worse outcomes when compared with asthma in younger populations. It is often underdiagnosed and undertreated, and as a result, elderly asthmatics suffer worse health outcomes from asthma. The primary aim of this thesis was to determine if asthma in the elderly is physiologically different to asthma in younger subjects. Airway hyperresponsiveness (AHR) was used as a physiological marker of asthma. Firstly, we found that the severity of AHR in older asthmatics is predicted by residual volume and peripheral airway ventilation heterogeneity. These predictors are different to those which predict the severity of AHR in younger asthmatics. Secondly, we found that the predictors of AHR severity are different in age matched asthmatics and COPD subjects, indicating that there is a disease-specific abnormality. Thirdly, we found that excessive airway closure with bronchoconstriction increases with disease duration and is predicted by baseline conducting airway ventilation heterogeneity and gas trapping. Finally, we found that increased peripheral airway ventilation heterogeneity in elderly asthmatics is related to lung volumes and not to increases in lung compliance. Thus, these studies provide strong evidence that asthma in the elderly is physiologically different to asthma in young people. Furthermore, they provide new information about the site and nature of the physiological determinants of AHR in the elderly

Ventilation heterogeneity is associated with airway responsiveness in asthma but not COPD

Airway hyperresponsiveness (AHR) occurs in both asthma and COPD. In older people with asthma, AHR is associated with increased acinar ventilation heterogeneity, but it is unknown if this association exists in COPD.Thirty one COPD and 19 age-matched asthmatic subjects had measures of spirometry, lung volumes, exhaled nitric oxide, ventilation heterogeneity, and methacholine challenge. Indices of acinar (Sacin) and conducting (Scond) airway ventilation heterogeneity were calculated from the multiple breath nitrogen washout. Predictors of AHR were then determined.In COPD, AHR was predicted by lower Sacin and lower FVC (model r 2 =0.35, p=0.001). In asthma, AHR was predicted by higher Sacin and higher residual volume (model r 2 =0.62, p \u3c 0.001).These findings suggest that airway responsiveness in COPD and asthma is determined by underlying disease-specific processes, rather than a common pattern of physiological abnormality. 2013 Elsevier Ltd.V

The role of the small airways in the clinical expression of asthma in adults

Background: The clinical relevance of increased ventilation heterogeneity, a marker of small-airways disease, in asthmatic patients is unclear. Ventilation heterogeneity is an independent determinant of airway hyperresponsiveness (AHR), improves with bronchodilators and inhaled corticosteroids (ICSs), and worsens during exacerbations, but its relationship to asthma control is unknown. Objective: We sought to determine the association between ventilation heterogeneity and current asthma control before and after ICS treatment. Methods: Adult subjects with asthma had lung function and asthma control (5-item Asthma Control Questionnaire [ACQ-5 score] ≥1.5 = poorly controlled, ACQ-5 score ≤0.75 = well controlled) measured at baseline. A subgroup with AHR had repeat measurements after 3 months of high-dose ICS treatment. The indices of ventilation heterogeneity in the regions of the lung where gas transport occurs predominantly through convection (ventilation heterogeneity in convection-dependent airways [Scond] ) and through diffusion (ventilation heterogeneity in diffusion-dependent airways [Sacin]) were derived by using the multiple-breath nitrogen washout technique. Results: At baseline (n = 105), subjects with poorly controlled asthma had worse FEV 1 , fraction of exhaled nitric oxide measured at 200 mL/s (Feno), Scond, and Sacin values. In the treatment group (n = 50) spirometric, Feno, residual volume (RV)/total lung capacity (TLC), AHR, and Scond values significantly improved. Asthma control also improved (mean ACQ-5 score, 1.3-0.7; P \u3c .0001). The change in ACQ-5 score correlated with changes in Feno (r s = 0.31, P =.03), Sacin (r s = 0.32, P =.02), and Scond (r s = 0.41, P =.003) values. The independent predictors of a change in asthma control were changes in Scond and Sacin values (model r 2 = 0.20, P =.005). Conclusions: Current asthma control is associated with markers of small-airways disease. Improvements in ventilation heterogeneity with anti-inflammatory therapy are associated with improvements in symptoms. Sensitive measures of small-airway function might be useful in monitoring the response to therapy in asthmatic subjects. 2012 American Academy of Allergy, Asthma & Immunology

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Background: Age-related increases in morbidity and mortality due to asthma may be due to changes in pathophysiology as patients with asthma get older. There is limited knowledge about the effects of age on the predictors of airway hyperresponsiveness (AHR), a key feature of asthma. The aim of this study was to determine if the pathophysiologic predictors of AHR, including inflammation, ventilation heterogeneity, and airway closure, differed between young and old patients with asthma. Methods: Sixty-one young (18-46 years) and 43 old (50-80 years) patients with asthma had lung function, lung volumes, fraction of exhaled nitric oxide, ventilation heterogeneity, and airway responsiveness to methacholine measured. Airway response to methacholine was measured by the dose-response slope, as the percent fall in FEV per micromole of methacholine. Indices of ventilation heterogeneity were calculated for convection-dependent and diffusion-dependent airways. Results: In young patients with asthma, the independent predictors of AHR were convection-dependent ventilation heterogeneity, exhaled nitric oxide, and % predicted FEV /FVC (model r=0.51,

Association between peripheral airway function and neutrophilic inflammation in asthma

Background and objectiveSmall airway dysfunction is associated with asthma severity and control, but its association with airway inflammation is unknown. The aim was to determine the association between sputum inflammatory cells and the site of small airway dysfunction, measured by multiple breath nitrogen washout in convection-dependent (Scond) and more peripheral diffusion-dependent (Sacin) airways. MethodsFifty-three (20-67 years) subjects with asthma on inhaled corticosteroid (ICS) treatment were characterized by spirometry, Scond, Sacin and induced sputum differential counts. %Predicted values for Scond and Sacin were calculated from published reference equations to adjust for the effects of age. Univariate correlations were assessed using the Spearman test. Multivariate linear regressions were performed to account for potential confounders, including age, gender, disease duration, body mass index and ICS dose. ResultsSacin (%predicted) correlated significantly with neutrophil% (r(s)=0.33, P=0.02), ICS dose (r(s)=-0.28, P=0.04) and age (r(s)=0.27, P=0.05). In multivariate analysis, Sacin related only to neutrophil% (adjusted R-2=0.18, P=0.001). Scond (%predicted) correlated significantly only with eosinophil% (r(s)=0.39, P=0.004). There was a trend for a negative relationship with ICS dose (r(s)=-0.26, P=0.06). In multivariate analysis, Scond related to eosinophil% and ICS dose independently (adjusted R-2=0.12, P=0.02). ConclusionsAcinar and conductive airway dysfunction is associated with different inflammatory profiles in asthmatic airways, independently of the effects of age and disease duration. The association between acinar airway dysfunction and neutrophilic airway inflammation may have implications for asthma treatment. The aim of this cross-sectional study was to determine the association between sputum inflammatory cells and small airway dysfunction in asthma. This is the first report of an association between small airway dysfunction and neutrophilic airway inflammation. The results may have implications for asthma treatment