Aim: The prevalence of airway obstruction varies widely with the definition used. Objectives: To study differences in the prevalence of airway obstruction when applying four international guidelines to three population samples using four regression equations. Methods: We collected predicted values for forced expiratory volume in 1 s/forced vital capacity (FEV 1 /FVC) and its lower limit of normal (LLN) from the literature. FEV 1 /FVC from 40 646 adults (including 13 136 asymptomatic never smokers) aged 17-90+years were available from American, English and Dutch population based surveys. The prevalence of airway obstruction was determined by the LLN for FEV 1 /FVC, and by using the Global Initiative for Chronic Obstructive Lung Disease (GOLD), American Thoracic Society/European Respiratory Society (ATS/ERS) or British Thoracic Society (BTS) guidelines, initially in the healthy subgroup and then in the entire population. Results: The LLN for FEV 1 /FVC varied between prediction equations (57 available for men and 55 for women), and demonstrated marked negative age dependency. Median age at which the LLN fell below 0.70 in healthy subjects was 42 and 48 years in men and women, respectively. When applying the reference equations (Health Survey for England 1995-1996, National Health and Nutrition Examination Survey (NHANES) III, European Community for Coal and Steel (ECCS)/ERS and a Dutch population study) to the selected population samples, the prevalence of airway obstruction in healthy never smokers aged over 60 years varied for each guideline: 17-45% of men and 7-26% of women for GOLD; 0-18% of men and 0-16% of women for ATS/ERS; and 0-9% of men and 0-11% of women for BTS. GOLD guidelines caused false positive rates of up to 60% when applied to entire populations. Conclusions: Airway obstruction should be defined by FEV 1 /FVC and FEV 1 being below the LLN using appropriate reference equations.Chronic obstructive pulmonary disease (COPD) is a major public health concern as a cause of chronic morbidity and mortality.

BackgroundMeasurement of lung volumes across the life course is critical to the diagnosis and management of lung disease. The aim of the study was to use the Global Lung Function Initiative methodology to develop all-age multi-ethnic reference equations for lung volume indices determined using body plethysmography and gas dilution techniques.MethodsStatic lung volume data from body plethysmography and gas dilution techniques from individual, healthy participants were collated. Reference equations were derived using the LMS (lambda-mu-sigma) method and the generalised additive models of location shape and scale programme in R. The impact of measurement technique, equipment type and being overweight or obese on the derived lung volume reference ranges was assessed.ResultsData from 17 centres were submitted and reference equations were derived from 7190 observations from participants of European ancestry between the ages of 5 and 80 years. Data from non-European ancestry populations were insufficient to develop multi-ethnic equations. Measurements of functional residual capacity (FRC) collected using plethysmography and dilution techniques showed physiologically insignificant differences and were combined. Sex-specific reference equations including height and age were developed for total lung capacity (TLC), FRC, residual volume (RV), inspiratory capacity, vital capacity, expiratory reserve volume and RV/TLC. The derived equations were similar to previously published equations for FRC and TLC, with closer agreement during childhood and adolescence than in adulthood.ConclusionsGlobal Lung Function Initiative reference equations for lung volumes provide a generalisable standard for reporting and interpretation of lung volumes measurements in individuals of European ancestry.

No abstract

The Global Lung Function Initiative (GLI) Network has become the largest resource for reference values for routine lung function testing ever assembled. This article addresses how the GLI Network came about, why it is important, and its current challenges and future directions. It is an extension of an article published in Breathe in 2013 [1], and summarises recent developments and the future of the GLI Network.Key pointsThe Global Lung Function Initiative (GLI) Network was established as a result of international collaboration, and altruism between researchers, clinicians and industry partners. The ongoing success of the GLI relies on network members continuing to work together to further improve how lung function is reported and interpreted across all age groups around the world.The GLI Network has produced standardised lung function reference values for spirometry and gas transfer tests.GLI reference equations should be adopted immediately for spirometry and gas transfer by clinicians and physiologists worldwide.The recently established GLI data repository will allow ongoing development and evaluation of reference values, and will offer opportunities for novel research.Educational aimsTo highlight the advances made by the GLI Network during the past 5 years.To highlight the importance of using GLI reference values for routine lung function testing (e.g. spirometry and gas transfer tests).To discuss the challenges that remain for developing and improving reference values for lung function tests.

Pulmonary function testing is often considered the basis for diagnosis in many categories of pulmonary disease. Although most of the testing methodologies are well established and widely employed, there are still many questions regarding how tests should be performed, how to ensure that reliable data are produced, what reference values and rules should be used, and how pulmonary function tests (PFTs) should be interpreted to best support clinical decision making. This conference was organized around a set of questions aimed at many of these issues. Each presenter was asked to address a specific topic regarding what tests should be done, how those test should be performed to answer a particular clinical question, and to relate test results to an accurate diagnosis and appropriate treatment of the patient. These topics included testing of adults and children, with concentration on important disease entities such as COPD, asthma, and unexplained dyspnea. Special emphasis was given to discussing reference values, lower limits of normal, interpretive strategies to optimize disease classification, and those factors directly affecting data quality. Established techniques for spirometry, lung volumes, diffusing capacity, exercise testing, and bronchial challenges were compared and contrasted with new technologies, and with technologies that might be part of pulmonary function laboratories in the near future.

No abstract

No abstract

Improved ventilation and exercise capacity follows thoracoscopic lung volume reduction surgery (TLVRS) in patients with severe emphysema. This improvement could be related to changes in inspiratory and expiratory flows following surgery, with consequent improvement in dyspnea indices. Changes in inspiratory/expiratory flows at rest and exercise and their relation to subjective improvement in dyspnea after TLVRS are not well known. We studied 25 patients with severe emphysema who underwent unilateral TLVRS performed in well-defined zones with decreased perfusion in nuclear medicine lung scans. Early follow-up after surgery (4.2 +/- 0.8 mo) showed significant improvements in exercise tolerance: The distance covered over a 6 min walk test increased from 934 +/- 297 to 1,071 +/- 241 ft (p = 0.01). Exercise tolerance using a bicycle ergometer showed increased exercise endurance from 4.43 +/- 1.7 to 5.71 +/- 1.8 min (p < 0.001). The maximum workload tolerated increased from 37 +/- 19 to 52 +/- 21 W (p < 0.01) and VO2 max changed from 9.7 +/- 2 to 11.8 +/- 3 (ml.kg)/min (p < 0.01). This increment was achieved by generating significantly larger minute ventilation (VE), from 24 +/- 11 to 29 +/- 10 L/min, reached through larger tidal volumes (increasing from 951 +/- 330 to 1,145 +/- 367 ml), while maintaining the same maximum respiratory rates. Increased VE was also accompanied by significant increases in both average inspiratory and expiratory flows measured during exercise: from 0.89 +/- 0.41 L/s to 1.06 +/- 0.08 L/s, and from 0.77 +/- 0.37 to 0.90 +/- 0.32 L/s respectively (p < 0.01). The parallel increment in flows resulted in constant T1/Ttot relationship. These functional changes correlated with increased inspiratory flows at rest measured with pulmonary function tests (forced inspiratory volume in one s [FIV1], expiratory flows [FVC, FEV1], and increased maximum voluntary ventilation [MVV]) following the surgically induced reduction in residual volume (RV). These objective changes occurred parallel to improved dyspnea indices. The Baseline Focal Score was 3.36 +/- 1.47 and the Transition Focal Score was 6.12 +/- 0.7. The objectively measured variables at rest that best correlated with subjective improvement in dyspnea were the change in MVV, change in resting arterial PaO2, and change in FEV1 following TLVRS. Exercise variables did not have significant correlation with subjective markers indicating improvement in dyspnea, with the exception of the change in Dyspneic Index [(VE/MVV)100] at maximum exercise.