Updated reference values for static lung volumes from a healthy population in Austria.

BACKGROUND: Reference values for lung volumes are necessary to identify and diagnose restrictive lung diseases and hyperinflation, but the values have to be validated in the relevant population. Our aim was to investigate the Global Lung Function Initiative (GLI) reference equations in a representative healthy Austrian population and create population-derived reference equations if poor fit was observed. METHODS: We analysed spirometry and body plethysmography data from 5371 respiratory healthy subjects (6-80 years) from the Austrian LEAD Study. Fit with the GLI equations was examined using z-scores and distributions within the limits of normality. LEAD reference equations were then created using the LMS method and the generalized additive model of location shape and scale package according to GLI models. RESULTS: Good fit, defined as mean z-scores between + 0.5 and -0.5,was not observed for the GLI static lung volume equations, with mean z-scores > 0.5 for residual volume (RV), RV/TLC (total lung capacity) and TLC in both sexes, and for expiratory reserve volume (ERV) and inspiratory capacity in females. Distribution within the limits of normality were shifted to the upper limit except for ERV. Population-derived reference equations from the LEAD cohort showed superior fit for lung volumes and provided reproducible results. CONCLUSION: GLI lung volume reference equations demonstrated a poor fit for our cohort, especially in females. Therefore a new set of Austrian reference equations for static lung volumes was developed, that can be applied to both children and adults (6-80 years of age).

Using the gli spirographic prediction equations to revisit the allometric relationships between lung volumes, height and age in adults.

The determination the forced vital capacity (FVC) and the forced expiratory volume in 1 second (FEV1) during spirometry studies, is at the core of the evaluation of the pulmonary function of patients with respiratory diseases. The Global Lung Function Initiative (GLI) offers the most extensive data set of normal lung functions available, which is currently used to determine the average expected/predicted FEV1 and FVC (predV), and their lower limit of normal (LLN, 5th percentile) at any given height and age for women and men. These prediction equations are currently expressed in a rather complex form: predV = exp [p+ (a x Ln (height) + (n x Ln (age)) + spline] and LLN = exp(Ln (predV) + Ln (1 - 1.645 x S x CV)/S); and are currently used to generate interpretations in commercialized spinographic system. However, as shown in this paper, these equations contain physiological and fundamental allometric information on lung volumes that become obvious when rewriting mean predicted values as a "simple" power function of height and LLN as a percentage of the mean predicted values. We therefore propose to present the equations of prediction obtained from the GLI data using simplified expressions in adults (18-95 years old) to reveal some of their physiological and allometric meaning. Indeed, when predicted FEV1 and FVC (predV) were expressed under the form predV= αx heightax b(age), the resulting exponent (a) ranges between 2 and 3, transforming the one dimension of a length (size) into a volume, akin to the third-order power (cubic) function of height historically used to predict lung volumes. Only one function, b (age), is necessary to replace all the factors related to age, including the tables of discrete data of spline functions original equations. Similarly, LLN can be expressed as LLN = c (age) xpredV to become a simple percentage of the predicted values, as a function of age. The equations with their respective new polynomial functions were validated in 52,764 consecutive spirometry tests performed in 2022 in 22,612 men and 30,152 women at the Cleveland Clinic. Using these equations, it become obvious that for both women and men, FEV1/FVC ratio decreases with the size as the exponent of the power function of height is lower for FEV1 than FVC. We conclude that rewriting the GLI predicted equations with simpler formulations restitutes to the GLI data some of their original allometric meaning, without altering the accuracy of their prediction.

Preserved Ratio Impaired Spirometry (PRISm): A Global Epidemiological Overview, Radiographic Characteristics, Comorbid Associations, and Differentiation from Chronic Obstructive Pulmonary Disease.

Preserved Ratio Impaired Spirometry (PRISm) manifests notable epidemiological disparities across the globe, with its prevalence and influential factors showcasing pronounced diversities among various geographical territories and demographics. The prevalence of PRISm fluctuates considerably among regions such as Latin America, the United States, and Asian nations, potentially correlating with a myriad of determinants, including socioeconomic status, environmental factors, and lifestyle modalities. Concurrently, the link between PRISm and health risks and other disorders, especially its distinction and interrelation with chronic obstructive pulmonary disease (COPD), has become a pivotal subject of scientific enquiry. Radiographic anomalies, such as perturbations in the pulmonary parenchyma and structural alterations, are posited as salient characteristics of PRISm. Furthermore, PRISm unveils intricate associations with multiple comorbidities, inclusive of hypertension and type 2 diabetes, thereby amplifying the intricacy in comprehending and managing this condition. In this review, we aim to holistically elucidate the epidemiological peculiarities of PRISm, its potential aetiological contributors, its nexus with COPD, and its association with radiographic aberrations and other comorbidities. An integrative understanding of these dimensions will provide pivotal insights for the formulation of more precise and personalised preventative and therapeutic strategies.

Lung Function Evaluated By Structured Light Plethysmography in Children After Lung Surgery: A Preliminary Analysis.

Background: Structured light plethysmography (SLP) is a novel light-based method that captures chest wall movements to evaluate tidal breathing. Methods: Thirty-two children who underwent lung surgery were enrolled. Their clinical history was collected along with spirometry and SLP. Results: Median age of surgery was 9 months (interquartile range 4-30). Most frequent diagnosis was congenital pulmonary airway malformation (14/32), then pulmonary sequestration (9/32), tumor (5/32), and bronchogenic cyst (4/32). The most frequent surgical approach was lobectomy (59%), segmentectomy (38%), and complete resection (3%). More than 80% had surgery when younger than 3 years of age. Eight patients had short-term complications (pleural effusion was the most frequent), while long-term effects were reported in 15 patients (19% recurrent cough, 13% thoracic deformities, 13% airway infections, 9% wheezing, 6% reduced exercise tolerance, and 3% columnar deformities). Spirometry was normal in 9/22 patients. Nine patients had a restrictive pattern, while 4 showed a mild bronco-reactivity. Ten patients did not perform spirometry because of young age. SLP revealed the presence of obstructive pattern in 10% of patients (IE50 > 1.88) and showed a significant difference between the two hemithorax in 29% of patients. Discussion: SLP may be a new method to evaluate lung function, without collaboration and radiation exposure, in children who underwent lung resection, also in preschool age.

FEV1Q: a race-neutral approach to assessing lung function.

BACKGROUND: Forced expiratory volume in 1 s quotient (FEV1Q) is a simple approach to spirometry interpretation that compares measured lung function to a lower boundary. This study evaluated how well FEV1Q predicts survival compared with current interpretation methods and whether race impacts FEV1Q. METHODS: White and Black adults with complete spirometry and mortality data from the National Health and Nutrition Examination Survey (NHANES) III and the United Network for Organ Sharing (UNOS) database for lung transplant referrals were included. FEV1Q was calculated as FEV1 divided by 0.4 L for females or 0.5 L for males. Cumulative distributions of FEV1 were compared across races. Cox proportional hazards models tested mortality risk from FEV1Q adjusting for age, sex, height, smoking, income and among UNOS individuals, referral diagnosis. Harrell's C-statistics were compared between absolute FEV1, FEV1Q, FEV1/height2, FEV1 z-scores and FEV1 % predicted. Analyses were stratified by race. RESULTS: Among 7182 individuals from NHANES III and 7149 from UNOS, 1907 (27%) and 991 (14%), respectively, were Black. The lower boundary FEV1 values did not differ between Black and White individuals in either population (FEV1 first percentile difference ≤0.01 L; p>0.05). Decreasing FEV1Q was associated with increasing hazard ratio (HR) for mortality (NHANES III HR 1.33 (95% CI 1.28-1.39) and UNOS HR 1.18 (95% CI 1.12-1.23)). The associations were not confounded nor modified by race. Discriminative power was highest for FEV1Q compared with alternative FEV1 approaches in both Black and White individuals. CONCLUSIONS: FEV1Q is an intuitive and simple race-neutral approach to interpreting FEV1 that predicts survival better than current alternative methods.

Acute Exacerbation and Longitudinal Lung Function Change of Preserved Ratio Impaired Spirometry.

Background: Preserved ratio impaired spirometry (PRISm) is a heterogeneous disease entity. Limited data are available regarding its prevalence, clinical course, or prognosis. We aimed to evaluate the longitudinal clinical course of patients with PRISm compared with chronic obstructive pulmonary disease (COPD). Methods: A retrospective study enrolled PRISm and COPD patients who underwent chest computed tomography and longitudinal pulmonary function tests between January 2013 and December 2020. We compared the incidence of acute exacerbations and lung function changes between PRISm and COPD patients. Results: Of the 623 patients, 40 and 583 had PRISm and COPD, respectively. Compared to COPD patients, PRISm patients were younger, more likely to be female and have a history of tuberculosis, and less likely to be smokers. They also had less severe comorbidities, lower forced vital capacity (FVC) and diffusing capacity of the lungs for carbon monoxide (DLCO). The clinical course was not significantly different between the PRISm and COPD patients in terms of the risk of moderate-to-severe acute exacerbations or proportion of frequent exacerbators. During follow-up, PRISm patients had a significantly slower annual decline of forced expiratory volume in 1 second, FVC, and DLCO than COPD patients. Conclusion: PRISm patients had no significant difference in the risk of acute exacerbations, but a significantly slower decline of lung function during longitudinal follow-up, compared with COPD patients.

The effect of incentive spirometry in perioperative patients with lung cancer-a systematic review and meta-analysis.

BACKGROUND: Incentive spirometry (IS) as a routine respiratory therapy during the perioperative period has been widely used in clinical practice. However, the impact of IS on patients with perioperative lung cancer remains controversial. This review aimed to evaluate the efficacy of IS in perioperative pulmonary rehabilitation for patients with lung cancer. METHODS: Cochrane Library, PubMed, Web of Science, Ovid, CINAHL, Chinese National Knowledge Infrastructure, Weipu, and Wanfang Databases were searched from inception to 30 November 2023. Only randomized controlled trials were included in this systematic review. The PRISMA checklist served as the guidance for conducting this review. The quality assessment of the included studies was assessed by the Cochrane risk-of-bias tool. The meta-analysis was carried out utilizing Review Manager 5.4. Furthermore, sensitivity analysis and subgroup analysis were also performed. RESULTS: Nine studies recruited 1209 patients met our inclusion criteria. IS combined with other respiratory therapy techniques was observed to reduce the incidence of postoperative pulmonary complications, enhance pulmonary function, curtail the length of hospital stay, and lower the Borg score. Nevertheless, no improvements were found in the six-minute walk distance or quality of life score. CONCLUSIONS: Although IS demonstrates benefits as a component of comprehensive intervention measures for perioperative patients with lung cancer, it proves challenging to determine the precise impact of IS as a standalone component within the comprehensive intervention measures. Therefore, further researches are required to better understand the effectiveness of IS isolation and its interactions when integrated with additional respiratory therapies for these patients. CLINICAL TRIAL REGISTRATION: PROSPERO, https://www.crd.york.ac.uk/prospero/ , registry number: CRD42022321044.

Prevalence and Associated Factors of Chronic Obstructive Pulmonary Disease Among Adults in Neno District, Malawi: A Cross-Sectional Analytical Study.

Introduction: Chronic obstructive pulmonary disease (COPD) continues to pose a global public health challenge. However, literature is scarce on the burden of COPD in Malawi. We assessed the prevalence and risk factors for COPD among adults in Neno, Malawi. Methodology: We conducted a population-based analytical cross-sectional study in Neno District between December 2021 and November 2022. Using a multi-stage sampling technique, we included 525 adults aged≥40 years. All participants underwent spirometry according to the American Thoracic Society (ATS) guidelines and were interviewed using the IMPALA questionnaire. For this study, we utilized the definition of COPD as a post-bronchodilator FEV1/FVC <0.70. We collected data using Kobo collect, exported to Microsoft Excel, and analysed using R software. We used descriptive statistics and logistic regression analysis; a p-value of <0.05 was considered statistically significant. Results: Out of 525 participants, 510 participants were included in the final analysis. Fifty-eight percent of the participants were females (n=296), and 62.2% (n=317) were between 40 and 49 years with a median (IQR) age of 46 (40-86). For patient characteristics, 15.1% (n=77) were current smokers, and 4.1% (n=21) had a history of pulmonary tuberculosis (PTB). Cough was the most commonly reported respiratory symptom (n=249, 48.8%). The prevalence of COPD was 10.0% (n=51) and higher (15.0%) among males compared to females (6.4%). Factors significantly associated with COPD were age 60 years and above (adjusted odds ratio [aOR] = 3.27, 95% CI: 1.48-7.34, p<0.004), ever smoked (aOR = 6.17, 95% CI:1.89-18.7, p<0.002), current smoker (aOR = 17.6, 95% CI: 8.47-38.4, p<0.001), and previous PTB (aOR = 4.42, 95% CI: 1.16-15.5, p<0.023). Conclusion: The cross-sectional prevalence of COPD in rural Malawi is high, especially among males. Factors significantly associated were older age (60 years and above), cigarette smoking, and previous PTB. Longitudinal studies are needed to better understand disease etiology and progression in this setting.

Comparison of particles in exhaled air and multiple breath washout for assessment of small airway function in children with cystic fibrosis.

BACKGROUND: The introduction of modulator therapy for cystic fibrosis (CF) has led to an increased interest in the detection of small airway disease (SAD) as sensitive marker of treatment response. The particles in exhaled air (PExA) method, which records exhaled particle mass (PEx ng/L) and number (PExNR), detects SAD in adult patients. Our primary aim was to investigate if PExA outcomes in children with CF are different when compared to controls and associated with more severe disease. Secondary aims were to assess feasibility and repeatability of PExA in children with CF and to correlate PExA to multiple breath nitrogen washout (MBNW) as an established marker of SAD. METHODS: Thirteen healthy children (HC), 17 children with CF with normal lung function (CF-N) (FEV1 z-score ≥ -1.64) and six with airway obstruction (CF-AO) (FEV1 z-score < -1.64) between 8 and 18 years performed MBNW followed by PExA and spirometry. Children with CF repeated the measurements after 3 months. RESULTS: PEx ng/L and PExNR/L per liter of exhaled breath were similar between the three groups. The lung clearance index (LCI) was significantly higher in both CF-N and CF-AO compared to HC. All participants, except one, were able to perform PExA. Coefficient of variation for PEx ng/l was (median) 0.38, range 0-1.25 and PExNR/l 0.38, 0-1.09. Correlation between LCI and PEx ng/l was low, rs 0.32 (p = .07). CONCLUSION: PExA is feasible in children. In contrast to LCI, PExA did not differentiate healthy children from children with CF suggesting it to be a less sensitive tool to detect SAD.

Small airways in asthma: From inflammation and pathophysiology to treatment response.

Small airways are characterized as those with an inner diameter less than 2 mm and constitute a major site of pathology and inflammation in asthma disease. It is estimated that small airways dysfunction may occur before the emergence of noticeable symptoms, spirometric abnormalities and imaging findings, thus characterizing them as "the quiet or silent zone" of the lungs. Despite their importance, measuring and quantifying small airways dysfunction presents a considerable challenge due to their inaccessibility in usual functional measurements, primarily due to their size and peripheral localization. Several pulmonary function tests have been proposed for the assessment of the small airways, including impulse oscillometry, nitrogen washout, body plethysmography, as well as imaging methods. Nevertheless, none of these methods has been established as the definitive "gold standard," thus, a combination of them should be used for an effective assessment of the small airways. Widely used asthma treatments seem to also affect several parameters of the small airways. Emerging biologic treatments show promising results in reducing small airways inflammation and remodelling, providing evidence for potential alterations in the disease's progression and outcomes. These novel therapies have implications not only in the clinical aspects of asthma but also in its inflammatory and functional aspects.

Effect of twice daily inhaled albuterol on cardiopulmonary exercise outcomes, dynamic hyperinflation, and symptoms in secondhand tobacco-exposed persons with preserved spirometry and air trapping: a randomized controlled trial.

BACKGROUND: In tobacco-exposed persons with preserved spirometry (active smoking or secondhand smoke [SHS] exposure), air trapping can identify a subset with worse symptoms and exercise capacity. The physiologic nature of air trapping in the absence of spirometric airflow obstruction remains unclear. The aim of this study was to examine the underlying pathophysiology of air trapping in the context of preserved spirometry and to determine the utility of bronchodilators in SHS tobacco-exposed persons with preserved spirometry and air trapping. METHODS: We performed a double-blinded placebo-controlled crossover randomized clinical trial in nonsmoking individuals at risk for COPD due to exposure to occupational SHS who had preserved spirometry and air trapping defined as either a residual volume-to-total lung capacity ratio (RV/TLC) > 0.35 or presence of expiratory flow limitation (EFL, overlap of tidal breathing on maximum expiratory flow-volume loop) on spirometry at rest or during cardiopulmonary exercise testing (CPET). Those with asthma or obesity were excluded. Participants underwent CPET at baseline and after 4-week trials of twice daily inhalation of 180 mcg of albuterol or placebo separated by a 2-week washout period. The primary outcome was peak oxygen consumption (VO2) on CPET. Data was analyzed by both intention-to-treat and per-protocol based on adherence to treatment prescribed. RESULTS: Overall, 42 participants completed the entire study (66 ± 8 years old, 91% female; forced expiratory volume in 1 s [FEV1] = 103 ± 16% predicted; FEV1 to forced vital capacity [FVC] ratio = 0.75 ± 0.05; RV/TLC = 0.39 ± 0.07; 85.7% with EFL). Adherence was high with 87% and 93% of prescribed doses taken in the treatment and placebo arms of the study, respectively (P = 0.349 for comparison between the two arms). There was no significant improvement in the primary or secondary outcomes by intention-to-treat or per-protocol analysis. In per-protocol subgroup analysis of those with RV/TLC > 0.35 and ≥ 90% adherence (n = 27), albuterol caused an improvement in peak VO2 (parameter estimate [95% confidence interval] = 0.108 [0.014, 0.202]; P = 0.037), tidal volume, minute ventilation, dynamic hyperinflation, and oxygen-pulse (all P < 0.05), but no change in symptoms or physical activity. CONCLUSIONS: Albuterol may improve exercise capacity in the subgroup of SHS tobacco-exposed persons with preserved spirometry and substantial air trapping. These findings suggest that air trapping in pre-COPD may be related to small airway disease that is not considered significant by spirometric indices of airflow obstruction.

Estimating the global prevalence of chronic obstructive pulmonary disease (COPD): a systematic review and meta-analysis.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a major public health problem. The present study aims to provide a global and regional estimate of the prevalence of COPD based on spirometry according to the two most widely used diagnostic criteria of COPD: fixed ratio (FR) and lower limit of normal (LLN). METHODS: We conducted a systematic review of the literature according to PRISMA guidelines. MEDLINE, Web of Sciences, and Scopus databases were searched to identify studies on the spirometry-based prevalence of COPD in individuals aged 40 years and older. The meta-analysis was performed using MedCalc 19 software. RESULTS: In total, 42 of the 3393 studies reviewed were eligible for inclusion. The overall prevalence of COPD in people aged 40 years and older was 12.64% (95% CI 10.75%-14.65%) and 7.38% (95% CI 5.47% - 9.55%) based on FR and LLN criteria, respectively. By gender, men had a higher prevalence of COPD compared to women (15.47%; 95% CI 12.22%-19.02% for men versus 8.79%; 95% CI 6.94%-10.82% for women). Using the LLN criteria, the prevalence of COPD in both sexes was almost identical (8.67%; 95% CI 8.44%- 8.90% for men and 8.00%; 95% CI 6.42% - 9.73% for women). We reported a high prevalence of COPD among smokers and the elderly by both definitions of airway obstruction. Regional prevalence estimates using the FR definition indicate that the highest COPD prevalence was recorded in the Americas and the lowest was recorded in the Eastern Mediterranean region. Using the LLN definition, the highest prevalence was recorded in the Southeast Asian region and the lowest prevalence was recorded in the American region. The most common COPD stage was stage II, with a prevalence of 50.46%. The results indicate a huge lack of prevalence data in the African and Eastern Mediterranean region. The results were given using a random-effect model due to the high heterogeneity between studies. CONCLUSION: Results show that the prevalence of COPD differs according to the diagnostic criteria used. In addition, management and prevention strategies targeting risk factors for COPD are certainly needed to reduce the global burden of this chronic respiratory disease.

Quality of spirometry tests in the field of occupational health.

BACKGROUND: The spirometry test is a valuable test to evaluate the performance of the respiratory system. The interpretation of the results is highly dependent on the quality of its performance, while the inappropriate quality results in unwanted consequences for individuals and the healthcare system. This study investigated the quality of spirometry tests performed in occupational health. METHODS: In this cross-sectional study, the quality of 776 spirometry tests in different occupational centers by the specialists in Rasht, Iran, in 2020, based on the guidelines of the American Thoracic Society (ATS), was investigated. The quality and success rate of the test and the demographical characteristics of the operators and the participants were collected. All data was analyzed using SPSS software version 20. RESULTS: Out of 776 spirometry tests, about 69.7% were unacceptable. Among the unacceptable tests, a pause error between inhalation and exhalation was identified in 7.4% of tests. Additionally, 4.6% of the unacceptable tests exhibited a cough error within the first second, while an exhalation error of less than six was observed in 85%. Repeatability errors were found in 60.9% of the tests. Furthermore, among some errors, the communication error between the characteristics of the technicians and the test performance errors were evident. CONCLUSION: According to the results, most of the performed tests were unacceptable with no repeatability, which indicated that the validity and quality of spirometry tests and their interpretation were inappropriate in the field of occupational health in Rasht, Iran.

Remotely supervised spirometry versus laboratory-based spirometry during the COVID-19 pandemic: a retrospective analysis.

BACKGROUND: The COVID-19 pandemic has constrained access to spirometry, and the inherent risk of infectious transmission during aerosol-generating procedures has necessitated the rapid development of Remotely Supervised Spirometry (RSS). This innovative approach enables patients to perform spirometry tests at home, using a mobile connected spirometer, all under the real-time supervision of a technician through an online audio or video call. METHODS: In this retrospective study, we examined the quality of RSS in comparison to conventional Laboratory-based Spirometry (LS), using the same device and technician. Our sample included 242 patients, with 129 undergoing RSS and 113 participating in LS. The RSS group comprised 51 females (39.5%) with a median age of 37 years (range: 13-76 years). The LS group included 63 females (55.8%) with a median age of 36 years (range: 12-80 years). RESULTS: When comparing the RSS group to the LS group, the percentage of accurate Forced Expiratory Volume in one second (FEV1) measurements was 78% (n = 101) vs. 86% (n = 97), p = 0.177; for Forced Vital Capacity (FVC) it was 77% (n = 99) vs. 82% (n = 93), p = 0.365; and for both FEV1 and FVC, it was 75% (n = 97) vs. 81% (n = 92), p = 0.312, respectively. CONCLUSIONS: Our findings demonstrate no significant difference in the quality of spirometry testing between RSS and LS, a result that held true across all age groups, including patients aged over 65 years. The principal advantages of remote spirometry include improved access to pulmonary function tests, reduced infectious risk to curtail disease spread, and enhanced convenience for patients.

Adding oscillometry to spirometry in guidelines better identifies uncontrolled asthma, future exacerbations, and potential targeted therapy.

The objective of this review is to provide new advances in our understanding of the clinical importance of establishing peripheral airway impairment (PAI) by impulse oscillometry (IOS) and targeted therapy, which could result in better asthma outcomes. Data sources include PubMed and Google search, limited to English language and human disease, with key words IOS and asthma. Key findings include PAI being consistently associated with uncontrolled asthma across ethnicities, using IOS reference equations factoring Hispanic and White reference algorithms. It is noted that PAI is common even in patients considered well-controlled by asthma guidelines. In a large longitudinal analysis (Assessment of Small Airways Involved in Asthma or ATLANTIS study), a composite of R5-R20, AX, and X5 ordinal scores were independently predictive of asthma control and exacerbation in a multivariate analysis, but forced expiratory volume in 1 second was not significantly predictive of morbidities. However, combining forced expiratory volume in 1 second less than 80% with PAI resulted in greater odds of identifying uncontrolled asthma and exacerbations, than either alone. Applying an external validation method in children with asthma offers the clinician the IOS reference equations best fit for their own specific population. Several clinical phenotypes can also identify PAI with high probability, useful when IOS is not available. Poor asthma outcomes for obese patients with asthma are associated with dysanapsis and PAI, not obesity alone. Extrafine inhaled corticosteroids achieve better asthma control and improve peripheral airway function with fewer exacerbations at lower dosages than nonextrafine inhaled corticosteroid aerosols. In conclusion, these data support the benefit of adding IOS to spirometry in future asthma guidelines and suggest the potential benefit from targeted therapy.

Application of Global Lung Function Initiative Global Spirometry Reference Equations across a Large, Multicenter Pulmonary Function Lab Population.

Rationale: Global Lung Function Initiative (GLI) Global spirometry reference equations were recently derived to offer a "race-neutral" interpretation option. The impact of transitioning from the race-specific GLI-2012 to the GLI Global reference equations is unknown. Objectives: Describe the direction and magnitude of changes in predicted lung function measurements in a population of diverse race and ethnicity using GLI Global in place of GLI-2012 reference equations. Methods: In this multicenter cross-sectional study using a large pulmonary function laboratory database, 109,447 spirometry tests were reanalyzed using GLI Global reference equations and compared with the existing GLI-2012 standard, stratified by self-reported race and ethnicity. Measurements and Main Results: Mean FEV1 and FVC percent predicted increased in the White and Northeast Asian groups and decreased in the Black, Southeast Asian, and mixed/other race groups. The prevalence of obstruction increased by 9.7% in the White group, and prevalences of possible restriction increased by 51.1% and 37.1% in the Black and Southeast Asian groups, respectively. Using GLI Global in a population with equal representation of all five race and ethnicity groups altered the interpretation category for 10.2% of spirometry tests. Subjects who self-identified as Black were the only group with a relative increase in the frequency of abnormal spirometry test results (32.9%). Conclusions: The use of GLI Global reference equations will significantly impact spirometry interpretation. Although GLI Global offers an innovative approach to transition from race-specific reference equations, it is important to recognize the continued need to place these data within an appropriate clinical context.

Enhancing respiratory physiology education: innovative wet spirometer modifications for hands-on learning.

The use of wet spirometers, although once common, has greatly declined because these devices measure only static lung volumes and students often face technical issues in their use. In this study, the wet spirometer has been modified to investigate the fundamental laws of flow and different types of lung disease. This modification was achieved by changing the dimensions of the device, printing a scale on the bell, and attaching an airflow control system (ACS) between the corrugated tube and hollow tube of the inner cylinder. The ACS allowed for flow control during the exercises. Two exercises were performed: exercise I compared the parameters measured by the wet spirometer, modified spirometer, and computerized spirometer to determine the suitability of the modification, while exercise II tested the variables affecting flow. These exercises introduce students to data collection, analysis, and the use of statistical tests as they compare various spirometers. Additionally, students gain valuable experience in experimental design by conducting diverse experiments that investigate factors influencing flow dynamics. By plotting the results and participating in small group discussions, students can apply flow principles in respiratory and circulatory systems, offering a hands-on experience that integrates physics and physiology. The modified spirometer facilitated multifaceted topic exploration, surpassing the traditional wet spirometer's capabilities.NEW & NOTEWORTHY This activity involves cost-effective modifications to the wet spirometer, broadening its applicability. These modifications effectively address student challenges associated with wet spirometer handling and enhance comprehension of fluid dynamics, all without the need for costly simulations, wet experiments, or fragile instruments. By offering a hands-on experience without traditional limitations, our modified spirometer provides an accessible and engaging approach to respiratory physiology education.

Pattern recognition of forced oscillation technique measurement results using deep learning can identify asthmatic patients more accurately than setting reference ranges.

No official clinical reference values have been established for MostGraph, which measures total respiratory resistance and reactance using the forced oscillation technique, complicating result interpretation. This study aimed to establish a reference range for MostGraph measurements and examine its usefulness in discriminating participants with asthma from controls (participants without any respiratory diseases). The study also aimed to investigate the effectiveness of deep learning in discriminating between the two aforementioned groups. To establish reference ranges, the MostGraph measurements of healthy controls (n = 215) were power-transformed to distribute the data more normally. After inverse transformation, the mean ± standard deviation × 2 of the transformed values were used to establish the reference ranges. The number of measured items outside the reference ranges was evaluated to discriminate patients with asthma (n = 941) from controls. Additionally, MostGraph measurements were evaluated using deep learning. Although reference ranges were established, patients with asthma could not be discriminated from controls. However, with deep learning, we could discriminate between the two groups with 78% accuracy. Therefore, deep learning, which considers multiple measurements as a whole, was more effective in interpreting MostGraph measurement results than use of reference ranges, which considers each result individually.

Does Mild Coronavirus Disease 2019 Pneumonia in Healthy Adults Cause Permanent Small Airway Injury?

OBJECTIVES: Impulse oscillometry (IOS) is a type of oscillation technique that measures the input impedance (Z) of the respiratory system and can be used to detect pathological changes in the small airways at an early stage. Although coronavirus disease 2019 (COVID-19) affects the vascular and parenchymal structures in the lung, chronic postinfection coughs also may be attributed to small airway pathologies. Our research aimed to use IOS for the assessment of the presence of small airway resistance (R) in patients who have had COVID-19. METHODS: Thirty-eight patients with past COVID-19 infections and without any presence or medical treatment of an airway disease who presented to the post-COVID outpatient clinic with coughing symptoms were included in the study. The control group consisted of 17 patients with no past COVID-19 infection and without an airway disease. IOS and spirometry were performed twice in the case group, at 3 and 6 months after COVID-19. RESULTS: The mean age of the case group was 44.7 ± 12.3 years, whereas the mean age of the control group was 49.4 ± 11.8 years. The case group consisted of 38 patients, whereas 17 patients constituted the control group. No statistically significant difference was found between the two groups in the first and second test measurements, performed 3 months apart (P > 0.05). CONCLUSIONS: The fact that there was no difference between respiratory system impedance, airway resistance, and spirometry values between groups with and without past COVID-19 infections supported the hypothesis that small airways were not affected 3 months after COVID-19.

Comparison of the Diagnostic Performance of Five Clinical Questionnaires for Chronic Obstructive Pulmonary Disease.

Background: Chronic obstructive pulmonary disease (COPD) remains one of the most prevalent pathologies in the world and is among the leading causes of mortality and morbidity, partially due to underdiagnosis. The use of clinical questionnaires to identify high-risk individuals to take them to further diagnostic procedures has emerged as a strategy to address this problem. Objective: To compare the performance of the COULD IT BE COPD, CDQ, COPD-PS, LFQ, and PUMA questionnaires for COPD diagnosis. Methods: A cross-sectional study was carried out on subjects who underwent spirometry in the third-level center. Data were collected between January 2015 and March 2020. Bivariate analysis was performed between the study variables and the presence of COPD. The area under the receiver operating characteristics curve (AUC-ROC), sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), and negative likelihood ratio (LR-) for each questionnaire were calculated. The AUC-ROCs were compared with the DeLong test, considering a p value <0.05 statistically significant. Results: 681 subjects met the inclusion criteria and were taken to the final analysis. The prevalence of COPD was 27.5% (187/681). The mean age of the subjects was 65.9 years (SD ± 11.79); 46.3% (315/681) were female, and 83.6% (569/681) reported respiratory symptoms. Statistically significant relationship was found for COPD diagnosis with male sex, older age, respiratory symptoms, and exposure to wood smoke (p value <0.05). The AUC-ROCs of the questionnaires were between 0.581 and 0.681. The COULD IT BE COPD questionnaire had a lower discriminatory capacity AUC-ROC of 0.581, concerning the other scores (DeLong test, p = 0.0002). Conclusion: The CDQ, COPD-PS, LFQ, PUMA, and COULD IT BE COPD questionnaires have acceptable performance for the diagnosis of COPD together with low sensitivity and specificity. Therefore, its use must be complemented with other diagnostic tests or techniques such as pulmonary function tests.