Design and Evaluation of a Novel Venturi-Based Spirometer for Home Respiratory Monitoring.

The high cost and limited availability of home spirometers pose a significant barrier to effective respiratory disease management and monitoring. To address this challenge, this paper introduces a novel Venturi-based spirometer designed for home use, leveraging the Bernoulli principle. The device features a 3D-printed Venturi tube that narrows to create a pressure differential, which is measured by a differential pressure sensor and converted into airflow rate. The airflow is then integrated over time to calculate parameters such as the Forced Vital Capacity (FVC) and Forced Expiratory Volume in one second (FEV1). The system also includes a bacterial filter for hygienic use and a circuit board for data acquisition and streaming. Evaluation with eight healthy individuals demonstrated excellent test-retest reliability, with intraclass correlation coefficients (ICCs) of 0.955 for FVC and 0.853 for FEV1. Furthermore, when compared to standard Pulmonary Function Test (PFT) equipment, the spirometer exhibited strong correlation, with Pearson correlation coefficients of 0.992 for FVC and 0.968 for FEV1, and high reliability, with ICCs of 0.987 for FVC and 0.907 for FEV1. These findings suggest that the Venturi-based spirometer could significantly enhance access to spirometry at home. However, further large-scale validation and reliability studies are necessary to confirm its efficacy and reliability for widespread use.

Benefits of budesonide/glycopyrronium/formoterol fumarate dihydrate on lung function and exacerbations of COPD: a post-hoc analysis of the KRONOS study by blood eosinophil level and exacerbation history.

BACKGROUND: Japanese guidelines recommend triple inhaled corticosteroid (ICS)/long-acting muscarinic antagonist (LAMA)/long-acting ß2-agonist (LABA) therapy in patients with chronic obstructive pulmonary disease (COPD) and no concurrent asthma diagnosis who experience frequent exacerbations and have blood eosinophil (EOS) count ≥ 300 cells/mm3, and in patients with COPD and asthma with continuing/worsening symptoms despite receiving dual ICS/LABA therapy. These post-hoc analyses of the KRONOS study in patients with COPD and without an asthma diagnosis, examine the effects of fixed-dose triple therapy with budesonide/glycopyrronium/formoterol fumarate dihydrate (BGF) versus dual therapies on lung function and exacerbations based on blood EOS count - focusing on blood EOS count 100 to < 300 cells/mm3 - as a function of exacerbation history and COPD severity. METHODS: In KRONOS, patients were randomized to receive treatments that included BGF 320/14.4/10 µg, glycopyrronium/formoterol fumarate dihydrate (GFF) 14.4/10 µg, or budesonide/formoterol fumarate dihydrate (BFF) 320/10 µg via metered dose inhaler (two inhalations twice-daily for 24 weeks). These post-hoc analyses assessed changes from baseline in morning pre-dose trough forced expiratory volume in 1 s (FEV1) over 12-24 weeks and moderate or severe COPD exacerbations rates over 24 weeks. The KRONOS study was not prospectively powered for these subgroup analyses. RESULTS: Among patients with blood EOS count 100 to < 300 cells/mm3, least squares mean treatment differences for lung function improvement favored BGF over BFF in patients without an exacerbation history in the past year and in patients with moderate and severe COPD, with observed differences ranging from 62 ml to 73 ml across populations. In this same blood EOS population, moderate or severe exacerbation rates were reduced for BGF relative to GFF by 56% in patients without an exacerbation history in the past year, by 47% in patients with moderate COPD, and by 50% in patients with severe COPD. CONCLUSIONS: These post-hoc analyses of patients with moderate-to-very severe COPD from the KRONOS study seem to indicate clinicians may want to consider a step-up to triple therapy in patients with persistent/worsening symptoms with blood EOS count > 100 cells/mm3, even if disease severity is moderate and there is no recent history of exacerbations. TRIAL REGISTRATION: ClinicalTrials.gov registry number NCT02497001 (registration date, 13 July 2015).

Cobalt exposure and pulmonary function reduction in chronic obstructive pulmonary disease patients: the mediating role of club cell secretory protein.

BACKGROUND: Cobalt (Co) is a metal which is widely used in the industrial production. The previous studies found the toxic effects of environmental Co exposure on multiple organs. However, the correlation of blood Co concentration with lung function was inconsistent in patients with chronic obstructive pulmonary disease (COPD). METHODS: All 771 stable COPD patients were recruited. Peripheral blood and clinical information were collected. The levels of blood Co and serum CC16 were measured. RESULTS: Cross-sectional study suggested that the level of blood Co was inversely and dose-dependently related to lung function parameters. Each 1 ppm elevation of blood Co was related to 0.598 L decline in FVC, 0.465 L decline in FEV1, 6.540% decline in FEV1/FVC%, and 14.013% decline in FEV1%, respectively. Moreover, higher age, enrolled in winter, current-smoking, higher smoking amount, and inhaled corticosteroids prominently exacerbated the negative correlation between blood Co and lung function. Besides, serum CC16 content was gradually reduced with blood Co elevation in COPD patients. Besides, serum CC16 was positively correlated with lung function, and inversely related to blood Co. Additionally, decreased CC16 substantially mediated 11.45% and 6.37% Co-triggered downregulations in FEV1 and FEV1%, respectively. CONCLUSION: Blood Co elevation is closely related to the reductions of pulmonary function and serum CC16. CC16 exerts a significantly mediating role of Co-related to pulmonary function decrease among COPD patients.

Effects of increasing tidal volume and end-expiratory lung volume on induced bronchoconstriction in healthy humans.

BACKGROUND: Increasing functional residual capacity (FRC) or tidal volume (VT) reduces airway resistance and attenuates the response to bronchoconstrictor stimuli in animals and humans. What is unknown is which one of the above mechanisms is more effective in modulating airway caliber and whether their combination yields additive or synergistic effects. To address this question, we investigated the effects of increased FRC and increased VT in attenuating the bronchoconstriction induced by inhaled methacholine (MCh) in healthy humans. METHODS: Nineteen healthy volunteers were challenged with a single-dose of MCh and forced oscillation was used to measure inspiratory resistance at 5 and 19 Hz (R5 and R19), their difference (R5-19), and reactance at 5 Hz (X5) during spontaneous breathing and during imposed breathing patterns with increased FRC, or VT, or both. Importantly, in our experimental design we held the product of VT and breathing frequency (BF), i.e, minute ventilation (VE) fixed so as to better isolate the effects of changes in VT alone. RESULTS: Tripling VT from baseline FRC significantly attenuated the effects of MCh on R5, R19, R5-19 and X5. Doubling VT while halving BF had insignificant effects. Increasing FRC by either one or two VT significantly attenuated the effects of MCh on R5, R19, R5-19 and X5. Increasing both VT and FRC had additive effects on R5, R19, R5-19 and X5, but the effect of increasing FRC was more consistent than increasing VT thus suggesting larger bronchodilation. When compared at iso-volume, there were no differences among breathing patterns with the exception of when VT was three times larger than during spontaneous breathing. CONCLUSIONS: These data show that increasing FRC and VT can attenuate induced bronchoconstriction in healthy humans by additive effects that are mainly related to an increase of mean operational lung volume. We suggest that static stretching as with increasing FRC is more effective than tidal stretching at constant VE, possibly through a combination of effects on airway geometry and airway smooth muscle dynamics.

Lung function parameters are associated with acute mountain sickness and are improved at high and extreme altitude.

At altitude, factors such as decreased barometric pressure, low temperatures, and acclimatization might affect lung function. The effects of exposure and acclimatization to high-altitude on lung function were assessed in 39 subjects by repetitive spirometry up to 6022 m during a high-altitude expedition. Subjects were classified depending on the occurrence of acute mountain sickness (AMS) and summit success to evaluate whether lung function relates to successful climb and risk of developing AMS. Peak expiratory flow (PEF), forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) increased with progressive altitude (max. +20.2 %pred, +9.3 %pred, and +6.7 %pred, all p<0.05). Only PEF improved with acclimatization (BC1 vs. BC2, +7.2 %pred, p=0.044). At altitude FEV1 (p=0.008) and PEF (p<0.001) were lower in the AMS group. The risk of developing AMS was associated with lower baseline PEF (p<0.001) and longitudinal changes in PEF (p=0.008) and FEV1 (p<0.001). Lung function was not related to summit success (7126 m). Improvement in PEF after acclimatization might indicate respiratory muscle adaptation.

Prevalence and etiotypes of persistent airflow obstruction in the general population across the lifetime.

BACKGROUND AND OBJECTIVES: Different factors (etiotypes) can lead to persistent airflow obstruction (PAO) across the lifetime, including genetic factors, abnormal lung development, cigarette smoking, traffic pollution exposure, respiratory infections and asthma. Here we explore the prevalence of PAO and associated etiotypes in the general population in different age bins. METHODS: We studied 664 individuals with PAO (FEV1/FVC post bronchodilation (post-BD) below the lower limit of normal (LLN)) and 11,522 with normal lung function (FEV1/FVC, FEV1 and FVC ≥ LLN and ≤ upper limit of normal (ULN) post-BD) included in the LEAD Study (NCT01727518), a general population cohort in Vienna (Austria). For analysis, participants were stratified in three age bins (<25, 25-<50 and ≥ 50 years of age). RESULTS: PAO occurred in 3.8 % in females and 5.6 % in males of the cohort, and it increased with age. Most participants with PAO (57.5 %) reported respiratory symptoms, indicating a high burden of disease. PAO was associated with male sex (25-<50 years), ever smoking (>50 years), increased number of pack years (25-<50 years, >50 years), not being breastfed (<25 years) and ever diagnosis of asthma (in all age bins). Etiotypes varied by age bins with cigarette smoking being the most prevalent one, often in combination with traffic pollution exposure. CONCLUSION: In the general population PAO occurs in about 5 % of participants with a higher prevalence in older individuals. Etiotypes and associated factors for PAO accumulate with age.

Comparison of race-specific and race-neutral GLI spirometric reference equations with an Indian reference equation.

BACKGROUND: Despite the increasing popularity and use of Global Lung Function Initiative (GLI) spirometric reference equations, the appropriateness of the race-specific and race-neutral GLI spirometric reference models among the Indian population has not been systematically investigated. METHODS: In this cross-sectional analysis, we used spirometric measurements of 1123 healthy Indian adults (≥18 years of age). We computed reference values and z-scores for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and FEV1/FVC from race-specific and race-neutral GLI reference equations as well as from a widely used Indian reference equation. We studied heterogeneity between GLI equations and the Indian equations using Bland-Altman analysis, and the differences between the reference and observed values were compared using the Friedman test. RESULTS: In Bland-Altman analysis, significant heterogeneity in FVC and FEV1 between race-specific and Indian equations was observed (bias: 10.4 % and 14.1 %, respectively), with less bias for FEV1/FVC (3.76 %). The race-neutral equations showed almost similar bias (9.8 %, 13.8 %, and 3.8 % for FVC, FEV1, and FEV1/FVC, respectively). Median differences in race-specific reference values from observed values for FVC and FEV1 were 0.49L and 0.44L, respectively, decreasing slightly with race-neutral equations (0.46L and 0.43L) whereas Indian models showed minimal differences (FVC: 0.10L, FEV1: 0.05L). Z-scores for FVC and FEV1 were significantly different between race-specific and race-neutral GLI equations, and both differed from Indian equations. CONCLUSION: Both race-specific and race-neutral GLI reference equations are significantly different from the Indian equations, which underscores the importance of determining the suitability of global reference models before being used indiscriminately.

Association of bronchial disease on CT imaging and clinical definitions of chronic bronchitis in a single-center COPD phenotyping study.

INTRODUCTION: Chronic Bronchitis (CB) represents a phenotype of chronic obstructive pulmonary disease (COPD). While several definitions have been used for diagnosis, the relationship between clinical definitions and radiologic assessment of bronchial disease (BD) has not been well studied. The aim of this study was to evaluate the relationship between three clinical definitions of CB and radiographic findings of BD in spirometry-defined COPD patients. METHODS: A cross-sectional analysis was performed from a COPD phenotyping study. It was a prospective observational cohort. Participants had spirometry-defined COPD and available chest CT imaging. Comparison between CB definitions, Medical Research Council (CBMRC), St. George's Respiratory Questionnaire (CBSGRQ), COPD Assessment Test (CBCAT) and CT findings were performed using Cohen's Kappa, univariate and multivariate logistic regressions. RESULTS: Of 112 participants, 83 met inclusion criteria. Demographics included age of 70.1 ± 7.0 years old, predominantly male (59.0 %), 45.8 ± 30.8 pack-year history, 21.7 % actively smoking, and mean FEV1 61.5 ± 21.1 %. With MRC, SGRQ and CAT definitions, 22.9 %, 36.6 % and 28.0 % had CB, respectively. BD was more often present in CB compared to non-CB patients; however, it did not have a statistically significant relationship between any of the CB definitions. CBSGRQ had better agreement with radiographically assessed BD compared to the other two definitions. CONCLUSION: Identification of BD on CT was associated with the diagnoses of CB. However, agreement between imaging and definitions were not significant, suggesting radiologic findings of BD and criteria defining CB may not identify the same COPD phenotype. Research to standardize imaging and clinical methods is needed for more objective identification of COPD phenotypes.

High-resolution Computed Tomography Thorax Volumetric Assessment in Coronavirus Disease 2019 Patients and Correlation with Pulmonary Function Tests.

INTRODUCTION: Years after SARS coronavirus disease 2019 (COVID-19) recovery, residual pulmonary abnormalities may still exist. This brings on the question of whether or not COVID-19 could have comparable late consequences. Structural changes in the lungs after recovery can be better visualized using computed tomography (CT) thorax. Computed Tomography Lung Parenchymal changes during hospitalization by COVID-19 and after 4 months of follow-up to correlate with the volumetric high-resolution computed tomography thorax indices, Pulmonary function tests (PFTs) indices, SpO2, and 6 min Walking Test (6MWT). MATERIALS AND METHODS: This is a Hospital based cross-sectional study, with a follow-up among 100 Patients from 2020 to 2022. Each patient's different CT parameters and HRCT volumetric indices Normal Lung (NL), Normal Lung Percentage (NL%), Whole Lung (WL) were correlated with the PFT indices (Forced expiratory volume in 1s [FEV1], forced vital capacity [FVC], FEV1/FVC), Oxygen Saturation (SpO2) and 6-Minute Walking Test (6MWT). RESULTS: The mean NL (L) and NL% during COVID were significantly lower than the mean values 4 months post-COVID. Architectural distortion, bronchiolar dilatation, interstitial thickening, and parenchymal bands were reduced considerably after 4 months post-COVID, compared to during COVID. PFTs results, such as PFT indices, were not significantly different after 4 months post-COVID, compared to during COVID. SpO2 (%) and 6 MWT (m) were significantly increased. During COVID and post-COVID, the values of NL (L) and NL (%) had a significant positive correlation with PFT indices, SpO2, and 6MWT (m). CONCLUSION: Hence, the different CT indices (NL and NL%) can be used as a surrogate for functional recovery of COVID patients since it correlates with the PFT indices (FEV1 and FEV1/FVC), SpO2, and 6MWT post-COVID.

Résumé Introduction:Des années après la guérison du SRAS Covid-19, des anomalies pulmonaires résiduelles peuvent encore exister. Cela amène à se demander si le Covid-19 pourrait ou non avoir des conséquences tardives comparables. Les changements structurels dans les poumons après la récupération peuvent être mieux visualisés à l'aide de CT-Thorax. Étudier les changements CT post-Covid pendant l'hospitalisation et après quatre mois de suivi de l'infection, et corréler les indices volumétriques du thorax HRCT avec les indices des tests de la fonction pulmonaire (PFT), la SpO2 et le test de marche de 6 min (6MWT).Matériels et méthodes:Il s'agit d'une étude transversale en milieu hospitalier, avec un suivi de 100 patients de 2020 à 2022. Les différents paramètres CT et indices volumétriques HRCT de chaque patient Poumon normal (NL), Pourcentage pulmonaire normal (NL%), Les poumons entiers (WL) étaient corrélés avec les indices PFT (volume expiratoire forcé en 1 s [FEV1], capacité vitale forcée [FVC], FEV1/FVC), saturation en oxygène (SpO2) et test de marche de 6 minutes (6MWT).Résultats:Les moyennes NL (L) et NL% pendant le Covid étaient significativement inférieures aux valeurs moyennes 4 mois post-covid. La distorsion architecturale, la dilatation bronchiolaire, l'épaississement interstitiel et les bandes parenchymateuses ont été considérablement réduits après 4 mois post-covid, par rapport à pendant Covid. Les résultats des tests de la fonction pulmonaire, tels que les indices PFT, n'étaient pas significativement différents après 4 mois post-covid, par rapport à pendant Covid. SpO2 (%) et 6 MWT (m) ont été significativement augmentés. Pendant Covid et post-covid, les valeurs de NL (L) et NL (%) avaient une corrélation positive significative avec les indices PFT, SpO2 et 6 MWT (m).Conclusion:Ainsi, les différents indices CT (NL, NL %) peuvent être utilisés comme substitut de la récupération fonctionnelle des patients Covid car ils sont corrélés aux indices PFT (FEV1, FEV1/FVC), SpO2, 6-MWT post-covid.

Effects of trunk muscle strength training on lung function in healthy runners.

BACKGROUND: Abdominal pressure is important for athlete performance and conditioning, and lung function is implicated in running performance and economy. We aimed to determine the synergistic effects of trunk muscle strength training on abdominal pressure and lung function in university student runners. METHODS: A total of 18 healthy male runners participated in the study. Abdominal pressure was measured against air pressure applied by a cuff belt wrapped around the trunk. Forced expiratory volume in 1 second (FEV1) and FEV in 6 seconds (FEV6) were measured. Trunk muscle strength training was performed for 8 weeks, and abdominal pressure and lung function were compared preintervention as well as at 8 weeks and 6 months postintervention. Correlations between the preintervention abdominal pressure and FEV1 and FEV6, as well as the rate of change (Δ) of each item at each time point, were examined. RESULTS: Preintervention correlations between abdominal pressure and lung function were significant for abdominal pressure and FEV1 (r=0.475, P=0.047) and abdominal pressure and FEV6 (r=0.473, P=0.047). Significant correlations were found between Δabdominal pressure and ΔFEV1 (r=0.489, P=0.040) and Δabdominal pressure and ΔFEV6 (r=0.478, P=0.045) between preintervention and 8 weeks postintervention. Significant correlations were found between Δabdominal pressure and ΔFEV6 (r=0.557, P=0.016) between 8 weeks and 6 months postintervention. CONCLUSIONS: The trunk muscle strength training intervention improved abdominal pressure and lung function, and the rate of change was also positively correlated, suggesting a synergistic effect between the two.

A Secondary Analysis of Gender Respiratory Features for Ultrasonography Bilateral Diaphragm Thickness, Respiratory Pressures, and Pulmonary Function in Low Back Pain.

The aim of the present study was to determine the gender respiratory differences of bilateral diaphragm thickness, respiratory pressures, and pulmonary function in patients with low back pain (LBP). A sample of 90 participants with nonspecific LBP was recruited and matched paired by sex (45 women and 45 men). Respiratory outcomes included bilateral diaphragm thickness by ultrasonography, respiratory muscle strength by maximum inspiratory (MIP) and expiratory (MEP) pressures, and pulmonary function by forced expiratory volume during 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC spirometry parameters. The comparison of respiratory outcomes presented significant differences (p < 0.001), with a large effect size (d = 1.26-1.58) showing means differences (95% CI) for MIP of -32.26 (-42.99, -21.53) cm H2O, MEP of -50.66 (-64.08, -37.25) cm H2O, FEV1 of -0.92 (-1.18, -0.65) L, and FVC of -1.00 (-1.32, -0.69) L, with lower values for females versus males. Gender-based respiratory differences were presented for maximum respiratory pressures and pulmonary function in patients with nonspecific LBP. Women presented greater inspiratory and expiratory muscle weakness as well as worse lung function, although these differences were not linked to diaphragm thickness during normal breathing.

Spirometry Interpretation After Implementation of Race-Neutral Reference Equations in Children.

Importance: The implications of adopting race-neutral reference equations on spirometry interpretation in children remain unknown. Objective: To examine how spirometry results and patterns change when transitioning from Global Lung Function Initiative (GLI) race-specific reference equations (GLIR, 2012) to GLI race-neutral reference equations (GLIN, 2023). Design, Setting, and Participants: Cross-sectional study of spirometry tests conducted in children aged 6 to 21 years between 2012 and 2022 at 2 large academic pediatric institutions in the US. Data were analyzed from September 2023 to March 2024. Exposures: Data on participant characteristics and raw test measurements were collected. Forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and FEV1/FVC z scores and percent predicted were calculated using both GLIR and GLIN. In addition, test results were categorized into normal, obstructive, suspected restrictive, mixed, suspected dysanapsis, and uncategorized patterns based on z scores calculated using GLIR or GLIN. Main Outcomes: For each spirometry result, the difference between z scores and percent predicted when transitioning from GLIR to GLIN was calculated. The proportion of tests with a normal pattern and individual spirometry patterns changed by GLI reference equation applied were also examined. Results: Data from 24 630 children were analyzed (mean [SD] age, 12.1 [3.8] years). There were 3848 Black children (15.6%), 19 503 White children (79.2%), and 1279 children of other races (5.2%). Following implementation of GLIN, FEV1 and FVC z scores decreased in Black children (mean difference, -0.814; 95% CI, -0.823 to -0.806; P < .001; and -0.911; 95% CI, -0.921 to -0.902; P < .001, respectively), while FEV1 and FVC z scores slightly increased (0.073; 95% CI, 0.069 to 0.076; P < .001). Similar changes were found when using percent predicted. In Black children, the number of tests with a normal pattern decreased from 2642 (68.7%) to 2383 (61.9%) (χ21 = 204.81; P < .001), mostly due to tests with a normal pattern transitioning to a suspected restrictive or uncategorized pattern. Opposite, albeit smaller, changes in spirometry results and patterns were seen in White children. In adjusted models, Black children had approximately 3-fold higher odds than White children of changing spirometry pattern following the implementation of GLIN (adjusted odds ratio, 3.15; 95% CI, 2.86 to 3.48; P < .001). Conclusions: Pronounced differences in spirometry results and patterns were found when switching between GLI reference equations, which markedly differed by race. These findings suggest that the implementation of GLIN is likely to change the treatment of children with chronic lung diseases that are more prevalent in underrepresented minorities, such as asthma.

What constitutes an obstructive ventilatory impairment in a pediatric population? A study design.

INTRODUCTION: There is no clear consensus as to what constitutes an obstructive ventilatory impairment (OVI) in pediatric populations. AIM: To determine the percentage of children/adolescents having an OVI among those addressed for spirometry after taking into account the definitions advanced by some international scholarly societies [British Columbia (BC), British thoracic-society (BTS), Canadian thoracic society (CTS), European respiratory society and American thoracic society (ERS-ATS), global initiative for asthma (GINA), Irish college of general practitioners (ICGP), national asthma council (NAC), national institute of clinical excellence (NICE), Société de pneumologie de langue française, Société pédiatrique de pneumologie et allergologie (SPLF-SP2A), and South African thoracic society (SATS)]. METHODS: This bi-centric cross-sectional study involves two medical structures in Sousse/Tunisia, and will encompass children/adolescents aged 6-18 years. A medical questionnaire will be administered, clinical and anthropometric data will be collected, and the spirometric data will be measured by two spirometers. The following six definitions of OVI will be applied: i) GINA: Forced expiratory volume in 1 second (FEV1) < 80% and a FEV1/forced vital capacity (FVC) ≤ 0.90; ii) ICGP: FEV1/FVC < 0.70; iii) ERS-ATS or BTS or SATS or SPLF-SP2A or NAC: FEV1/FVC z-score < -1.645; iv) NICE: FEV1/FVC < 0.70 or FEV1/FVC z-score < -1.645; v) CTS: FEV1/FVC < 0.80 or a FEV1/FVC z-score < -1.645; and vi) ERS: "FEV1 z-score or FEV1/FVC z-score" < -1.645 or "FEV1 or FEV1/FVC" < 0.80. EXPECTED RESULTS: The percentage of children/adolescents having an OVI will significantly vary between the six definitions. CONCLUSION: The frequency of OVI in a pediatric population will depend on the definition chosen.

Association between bronchiectasis exacerbations and longitudinal changes in FEV1 in patients from the US bronchiectasis and NTM research registry.

BACKGROUND: This study aimed to evaluate the association between the number of non-cystic fibrosis bronchiectasis (bronchiectasis) exacerbations during baseline and follow-up (objective 1) and to identify longitudinal changes in FEV1 associated with exacerbation frequency (objective 2). METHODS: This was a retrospective cohort study of adult patients enrolled in the US Bronchiectasis and Nontuberculous Mycobacteria Research Registry September 2008 to March 2020. Objective 1 outcome was association between exacerbations during baseline (24 months) and 0-to-24 month and 24-to-48 month follow-up windows. Objective 2 outcomes were change in FEV1 and FEV1 % predicted over 24 months stratified by baseline exacerbation frequency. RESULTS: Objective 1 cohort (N = 520) baseline frequency of any exacerbations was 59.2%. Overall, 71.4% and 75.0% of patients with ≥1 baseline exacerbations had ≥1 exacerbations during the 0-to-24 and 24-to-48 month follow-ups. Having ≥1 exacerbation during baseline was significantly associated with ≥1 exacerbation during the 0-to-24 month (P = 0.0085) and 24-to-48 month follow-ups (P=<0.0001). Objective 2 cohort (N = 431) baseline FEV1 was significantly lower in patients who had more exacerbations; however, decline in FEV1 from baseline was not significantly different between patients with 0, 1, and ≥2 exacerbations. In patients with more baseline exacerbations, FEV1 % predicted was significantly lower at baseline (P < 0.0001) and at 12 (P = 0.0002) and 24 month follow-ups (P < 0.0001). CONCLUSIONS: Patients with frequent bronchiectasis exacerbations may be more likely than those with less frequent exacerbations to experience disease progression based on future exacerbation frequency and lower FEV1 at baseline, although FEV1 decline may not differ by baseline exacerbation frequency.

The prevalence and mortality risks of PRISm and COPD in the United States from NHANES 2007-2012.

BACKGROUND: We estimated the prevalence and mortality risks of preserved ratio impaired spirometry (PRISm) and chronic obstructive pulmonary disease (COPD) in the US adult population. METHODS: We linked three waves of pre-bronchodilator spirometry data from the US National Health and Nutritional Examination Survey (2007-2012) with the National Death Index. The analytic sample included adults ages 20 to 79 without missing data on age, sex, height, BMI, race/ethnicity, and smoking status. We defined COPD (GOLD 1, 2, and 3-4) and PRISm using FEV1/FVC cut points by the Global Initiative for Chronic Obstructive Lung Disease (GOLD). We compared the prevalence of GOLD stages and PRISm by covariates across the three waves. We estimated adjusted all-cause and cause-specific mortality risks by COPD stage and PRISm using all three waves combined. RESULTS: Prevalence of COPD and PRISm from 2007-2012 ranged from 13.1%-14.3% and 9.6%-10.2%, respectively. We found significant differences in prevalence by sex, age, smoking status, and race/ethnicity. Males had higher rates of COPD regardless of stage, while females had higher rates of PRISm. COPD prevalence increased with age, but not PRISm, which was highest among middle-aged individuals. Compared to current and never smokers, former smokers showed lower rates of PRISm but higher rates of GOLD 1. COPD prevalence was highest among non-Hispanic White individuals, and PRISm was notably higher among non-Hispanic Black individuals (range 31.4%-37.4%). We found associations between PRISm and all-cause mortality (hazard ratio [HR]: 2.3 95% CI: 1.9-2.9) and various cause-specific deaths (HR ranges: 2.0-5.3). We also found associations between GOLD 2 (HR: 2.1, 95% CI: 1.7-2.6) or higher (HR: 4.2, 95% CI: 2.7-6.5) and all-cause mortality. Cause-specific mortality risk varied within COPD stages but typically increased with higher GOLD stage. CONCLUSIONS: The prevalence of COPD and PRISm remained stable from 2007-2012. Greater attention should be paid to the potential impacts of PRISm due to its higher prevalence in minority groups and its associations with mortality across various causes including cancer.

Long COVID symptoms after 8-month recovery: persistent static lung hyperinflation associated with small airway dysfunction.

BACKGROUND: Limited research has investigated the relationship between small airway dysfunction (SAD) and static lung hyperinflation (SLH) in patients with post-acute sequelae of COVID-19 (PASC) especially dyspnea and fatigue. METHODS: 64 patients with PASC were enrolled between July 2020 and December 2022 in a prospective observational cohort. Pulmonary function tests, impulse oscillometry (IOS), and symptom questionnaires were performed two, five and eight months after acute infection. Multivariable logistic regression models were used to test the association between SLH and patient-reported outcomes. RESULTS: SLH prevalence was 53.1% (34/64), irrespective of COVID-19 severity. IOS parameters and circulating CD4/CD8 T-cell ratio were significantly correlated with residual volume to total lung capacity ratio (RV/TLC). Serum CD8 + T cell count was negatively correlated with forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) with statistical significance. Of the patients who had SLH at baseline, 57% continued to have persistent SLH after eight months of recovery, with these patients tending to be older and having dyspnea and fatigue. Post-COVID dyspnea was significantly associated with SLH and IOS parameters R5-R20, and AX with adjusted odds ratios 12.4, 12.8 and 7.6 respectively. SLH was also significantly associated with fatigue. CONCLUSION: SAD and a decreased serum CD4/CD8 ratio were associated with SLH in patients with PASC. SLH may persist after recovery from infection in a substantial proportion of patients. SAD and dysregulated T-cell immune response correlated with SLH may contribute to the development of dyspnea and fatigue in patients with PASC.

Which reference equation should we use for interpreting spirometry values for First Nations Australians? A cross-sectional study.

OBJECTIVES: To evaluate the suitability of the Global Lung Function Initiative (GLI)-2012 other/mixed and GLI-2022 global reference equations for evaluating the respiratory capacity of First Nations Australians. DESIGN, SETTING: Cross-sectional study; analysis of spirometry data collected by three prospective studies in Queensland, the Northern Territory, and Western Australia between March 2015 and December 2022. PARTICIPANTS: Opportunistically recruited First Nations participants in the Indigenous Respiratory Reference Values study (Queensland, Northern Territory; age, 3-25 years; 18 March 2015 - 24 November 2017), the Healthy Indigenous Lung Function Testing in Adults study (Queensland, Northern Territory; 18 years or older; 14 August 2019 - 15 December 2022) and the Many Healthy Lungs study (Western Australia; five years or older; 10 October 2018 - 7 November 2021). MAIN OUTCOME MEASURES: Goodness of fit to spirometry data for each GLI reference equation, based on mean Z-score and its standard deviation, and proportions of participants with respiratory parameter values within 1.64 Z-scores of the mean value. RESULTS: Acceptable and repeatable forced expiratory volume in the first second (FEV1) values were available for 2700 First Nations participants in the three trials; 1467 were classified as healthy and included in our analysis (1062 children, 405 adults). Their median age was 12 years (interquartile range, 9-19 years; range, 3-91 years), 768 (52%) were female, and 1013 were tested in rural or remote areas (69%). Acceptable and repeatable forced vital capacity (FVC) values were available for 1294 of the healthy participants (88%). The GLI-2012 other/mixed and GLI-2022 global equations provided good fits to the spirometry data; the race-neutral GLI-2022 global equation better accounted for the influence of ageing on FEV1 and FVC, and of height on FVC. Using the GLI-2012 other/mixed reference equation and after adjusting for age, sex, and height, mean FEV1 (estimated difference, -0.34; 95% confidence interval [CI], -0.46 to -0.22) and FVC Z-scores (estimated difference, -0.45; 95% CI, -0.59 to -0.32) were lower for rural or remote than for urban participants, but their mean FEV1/FVC Z-score was higher (estimated difference, 0.14; 95% CI, 0.03-0.25). CONCLUSION: The normal spirometry values of healthy First Nations Australians may be substantially higher than previously reported. Until more spirometry data are available for people in urban areas, the race-neutral GLI-2022 global or the GLI-2012 other/mixed reference equations can be used when assessing the respiratory function of First Nations Australians.

Lung function trajectories from school age to adulthood and their relationship with markers of cardiovascular disease risk.

RATIONALE: Lung function in early adulthood is associated with subsequent adverse health outcomes. OBJECTIVES: To ascertain whether stable and reproducible lung function trajectories can be derived in different populations and investigate their association with objective measures of cardiovascular structure and function. METHODS: Using latent profile modelling, we studied three population-based birth cohorts with repeat spirometry data from childhood into early adulthood to identify trajectories of forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC). We used multinomial logistic regression models to investigate early-life predictors of the derived trajectories. We then ascertained the extent of the association between the derived FEV1/FVC trajectories and blood pressure and echocardiographic markers of increased cardiovascular risk and stroke in ~3200 participants at age 24 years in one of our cohorts. RESULTS: We identified four FEV1/FVC trajectories with strikingly similar latent profiles across cohorts (pooled N=6377): above average (49.5%); average (38.3%); below average (10.6%); and persistently low (1.7%). Male sex, wheeze, asthma diagnosis/medication and allergic sensitisation were associated with trajectories with diminished lung function in all cohorts. We found evidence of an increase in cardiovascular risk markers ascertained by echocardiography (including left ventricular mass indexed to height and carotid intima-media thickness) with decreasing FEV1/FVC (with p values for the mean crude effects per-trajectory ranging from 0.10 to p<0.001). In this analysis, we considered trajectories as a pseudo-continuous variable; we confirmed the assumption of linearity in all the regression models. CONCLUSIONS: Childhood lung function trajectories may serve as predictors in the development of not only future lung disease, but also the cardiovascular disease and multimorbidity in adulthood.