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Introduction Whole-body plethysmography is the preferred method for measuring the static lung volumes: total lung capacity (TLC), functional residual capacity (FRC) and residual volume (RV), as it also incorporates trapped gas – a common finding in chronic obstructive pulmonary disease (COPD). Quantitative computed tomography (CT) is a promising alternative to plethysmography, which can be challenging to perform for patients with severely impaired lung function. The present systematic review explores the agreement between lung volumes measured by plethysmography and CT, as well as the attempts being made to optimize alignment between these two methods.Methods A literature search was performed on the PubMed database using the block search strategy. Articles were included if they provided both CT based and plethysmography based TLC. Risk of bias was evaluated using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) checklist.Results 22 articles were included. On average, CT-derived TLC (CT-TLC) was 709 mL lower compared to plethysmography TLC (p-TLC) with a 12.1% deviation from the reference standard, p-TLC. This discrepancy (ΔTLC) appeared slightly larger in obstructive patients (obstructive: 781 mL, non-obstructive: 609 mL), whereas percent deviation was slightly smaller (obstructive: 11.4%, non-obstructive: 13.5%). CT-based RV analyses primarily based on COPD patients measured 603 mL higher than plethysmography (p-RV) with 17.8% deviation from p-RV. Studies utilizing spirometry-gating for CT acquisition reported good agreement between modalities (ΔTLC: 70–280 mL), and one study demonstrated noticeable improvements compared to conventional breath-hold instructions in an otherwise identical study setting.Conclusion CT quantifications routinely underestimate TLC and overestimate RV in comparison to plethysmography. Spirometry gating reduces the level of disagreement and can be of assistance when patients are already undergoing CT. However, further studies are needed to confirm these results.

Physiological methods for measuring total lung capacity (TLC), including body-box plethysmography (BBP), are costly and require specialized expertise. Computed tomography (CT)-based TLC assessment is essential in clinical practice for candidates of lung transplantation and those unable to undergo standard lung function testing. While CT-based algorithms were studied to estimate TLC, their accuracy should be further evaluated. This study aimed to compare the BBP measurement of TLC (TLCpleth) with three CT-based methods for measuring TLC, one of them is an innovative virtual reality (VR)-based method. Additionally, we aimed to develop an adjustment factor that will allow a new, non-invasive, cost-effective estimation of the TLCpleth. TLC was calculated for 24 adult patients using three different CT-based volumetric assessment methods: an older region-growing algorithm (TLCrg), a more recent convolutional neural network-based algorithm (TLCcnn), and a VR-based method (TLCvr). Agreement between each method and TLCpleth was evaluated, and an adjustment factor was developed using linear regression. The correlation between the three CT-based methods and TLCpleth ranged from 0.91 to 0.92 (p < 0.001). TLCvr measurements were 80.13% (CI:75.08–85.18%, P < 0.001) of TLCpleth measures, whereas TLCcnn and TLCrg estimates were 71.3% and 77.1% of TLCpleth, respectively. An adjustment factor is proposed to estimate TLCpleth based on the three CT-based methods. This study is the first to evaluate the correlation between BBP, VR volumetric analysis, and two iterations of CT volumetric software for measuring total lung capacity (TLC). After being corrected by an adjustment factor, VR- and CT-based assessments provide accurate estimates of TLCpleth. [ABSTRACT FROM AUTHOR]

We measured resting metabolic rate (RMR), tidal volume (VT), breathing frequency (fR), respiratory flow, and end‐expired gases in rough‐toothed dolphins (Steno bredanensis) housed in managed care after an overnight fast and 1–2 hr following a meal. The measured average (± standard deviation) VT (4.0 ± 1.3 L) and fR (1.9 ± 1.0 breaths/min) were higher and lower, respectively, as compared with estimated values from both terrestrial and aquatic mammals, and the average VT was 43% of the estimated total lung capacity. The end‐expired gas levels suggested that this species keep alveolar O2 (10.6% or 80 mmHg) and CO2 (7.6% or 57 mmHg), and likely arterial gas tensions, low and high, respectively, to maximize efficiency of gas exchange. We show that following an overnight fast, the RMR (566 ± 158 ml O2/min) was 1.8 times the estimated value predicted by Kleiber for terrestrial mammals of the same size. We also show that between 1 and 2 hr after ingestion of a meal, the metabolic rate increases an average of 29% (709 ± 126 ml O2/min). Both body mass (Mb) and fR significantly altered the measured RMR and we propose that both these variables should be measured when estimating energy use in cetaceans. [ABSTRACT FROM AUTHOR]

Background: Total lung capacity (TLC) is the volume of air in the lungs at the end of a maximal inhalation. TLC mainly depends on various factors/predictors such as height, age, gender, and ethnicity, and therefore, population-specific reference equations should be used. Currently, in India, we use the (European committee for coal and steel [ECCS], published in the year 1993) reference equation with no correction factor for TLC. It is recommended that the reference equation should be tested on a sample of local healthy participants, differences between the measured values and the predicted values are determined to see if the reference equation is a suitable/good fit for the population. Aim: The aim of this study was to compare the actual values of TLC from the healthy male and female volunteers from Pune city with the reference values obtained from the ECCS equations in these participants and determine the correction factor/percent differences between the mean values for different age and height groups. Design and Setting: A prospective, cross-sectional study of lung function measurements (TLC) by body plethysmography was carried out in a research center. Methodology: TLC was measured by Jaeger's Body Plethysmograph (model: Master scope) according to the recommendation of the American Thoracic Society's/European Respiratory Society's standards 2005 in a sample of 241 healthy nonsmoking volunteers (150 men and 82 women) aged 20-70 years, living in Pune city of Maharashtra, India. Statistical Analysis: The mean of actual TLC and the reference TLC were plotted against the different age groups and height groups and percentage difference was determined. Multiple linear regression was carried out to find the predictive equations for TLC parameter measured by the body plethysmography. Age, height, and weight were used as the predictors (independent variables) in the multiple regression analysis. Since sex is also a predictor of TLC, separate models were run for men and women. Results: There were statistically significant differences between the measured TLC and the reference TLC obtained from the ECCS equation in both males (5.05 L ± 0.69 vs. 6.3 L ± 0.50) and females (3.69 L ± 0.54 vs. 4.39 L ± 0.36), respectively. Males have higher TLC as compared to females of the same age and height. The mean of actual TLC and the reference TLC was plotted against different age groups and height groups, and percentage difference was determined. The percentage differences ranged from 17% to 21% in males and 13%-17% in females. Conclusion: The ECCS equation is not suitable for Pune population and may lead to misinterpretation of restrictive lung diseases and hyperinflation. A correction factor of 18.5% in males and 15% in females may be used for the ECCS equation for TLC in Pune population. [ABSTRACT FROM AUTHOR]

Background: Total lung capacity (TLC) is the volume of air in the lungs at the end of a maximal inhalation. TLC mainly depends on various factors/predictors such as height, age, gender, and ethnicity, and therefore, population-specific reference equations should be used. Currently, in India, we use the (European committee for coal and steel [ECCS], published in the year 1993) reference equation with no correction factor for TLC. It is recommended that the reference equation should be tested on a sample of local healthy participants, differences between the measured values and the predicted values are determined to see if the reference equation is a suitable/good fit for the population. Aim: The aim of this study was to compare the actual values of TLC from the healthy male and female volunteers from Pune city with the reference values obtained from the ECCS equations in these participants and determine the correction factor/percent differences between the mean values for different age and height groups. Design and Setting: A prospective, cross-sectional study of lung function measurements (TLC) by body plethysmography was carried out in a research center. Methodology: TLC was measured by Jaeger's Body Plethysmograph (model: Master scope) according to the recommendation of the American Thoracic Society's/European Respiratory Society's standards 2005 in a sample of 241 healthy nonsmoking volunteers (150 men and 82 women) aged 20–70 years, living in Pune city of Maharashtra, India. Statistical Analysis: The mean of actual TLC and the reference TLC were plotted against the different age groups and height groups and percentage difference was determined. Multiple linear regression was carried out to find the predictive equations for TLC parameter measured by the body plethysmography. Age, height, and weight were used as the predictors (independent variables) in the multiple regression analysis. Since sex is also a predictor of TLC, separate models were run for men and women. Results: There were statistically significant differences between the measured TLC and the reference TLC obtained from the ECCS equation in both males (5.05 L ± 0.69 vs. 6.3 L ± 0.50) and females (3.69 L ± 0.54 vs. 4.39 L ± 0.36), respectively. Males have higher TLC as compared to females of the same age and height. The mean of actual TLC and the reference TLC was plotted against different age groups and height groups, and percentage difference was determined. The percentage differences ranged from 17% to 21% in males and 13%–17% in females. Conclusion: The ECCS equation is not suitable for Pune population and may lead to misinterpretation of restrictive lung diseases and hyperinflation. A correction factor of 18.5% in males and 15% in females may be used for the ECCS equation for TLC in Pune population.

Abstract Background Some evidences have shown the association between air pollution exposure and the development of interstitial lung diseases. However, the effect of air pollution on the progression of restrictive ventilatory impairment and diffusion capacity reduction is unknown. This study aimed to evaluate the effects of long-term exposure to ambient air pollution on the change rates of total lung capacity, residual volume, and diffusion capacity among the elderly. Methods From 2016 to 2018, single-breath helium dilution with the diffusion capacity of carbon monoxide was performed once per year on 543 elderly individuals. Monthly concentrations of ambient fine particulate matters (PM2.5) and nitric dioxide (NO2) at the individual residential address were estimated using a hybrid Kriging/Land-use regression model. Linear mixed models were used to evaluate the association between long-term (12 months) exposure to air pollution and lung function with adjustment for potential covariates, including basic characteristics, indoor air pollution (second-hand smoke, cooking fume, and incense burning), physician diagnosed diseases (asthma and chronic airway diseases), dusty job history, and short-term (lag one month) air pollution exposure. Results An interquartile range (5.37 ppb) increase in long-term exposure to NO2 was associated with an additional rate of decline in total lung volume (− 1.8% per year, 95% CI: − 2.8 to − 0.9%), residual volume (− 3.3% per year, 95% CI: − 5.0 to − 1.6%), ratio of residual volume to total lung volume (− 1.6% per year, 95% CI: − 2.6 to − 0.5%), and diffusion capacity (− 1.1% per year, 95% CI: − 2.0 to − 0.2%). There is no effect on the transfer factor (ratio of diffusion capacity to alveolar volume). The effect of NO2 remained robust after adjustment for PM2.5 exposure. Conclusions Long-term exposure to ambient NO2 is associated with an accelerated decline in static lung volume and diffusion capacity in the elderly. NO2 related air pollution may be a risk factor for restrictive lung disorders.

Background: The evaluation of COVID‐19 systemic consequences is a wide research field in which respiratory function assessment has a pivotal role. However, the available data in the literature are still sparse and need further strengthening. Aim: To assess respiratory function 4–6 months after hospital discharge based on lung disease severity in patients who overcome COVID‐19 pneumonia. Methods: Patients hospitalised either in the Internal Medicine Department (IMD) for moderate to severe disease or in the Intensive Care Unit (ICU) for critical disease underwent spirometry with maximal flow‐volume curve, lung volumes, lung diffusion capacity (DLCO) and six‐minute walking test (6‐MWT). Results: Eighty‐eight patients were analysed: 40 from the IMD and 48 from the ICU. In both cohorts, there was a greater prevalence of male patients. In the IMD cohort, 38% of patients showed at least one altered respiratory parameter, while 62% in the ICU cohort did so (P < 0.05). Total lung capacity (TLC) and DLCO were the most frequently altered parameters: 15% and 33% from IMD versus 33% and 56% from ICU, respectively (P < 0.05). In IMD patients, 5% had only restrictive deficit, 22% had only lung diffusion impairment and 10% had both. In ICU patients, 6% had only restrictive deficit, 29% had only lung diffusion impairment and 27% had both (P < 0.05). ICU patients showed a higher frequency of abnormal 6‐MWT (P < 0.05). Conclusion: Lung function tests and 6‐MWT are highly informative tools for monitoring the negative consequences of COVID‐19 pneumonia, which were more frequent and more complex in patients discharged from ICU. [ABSTRACT FROM AUTHOR]

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Background and objectiveSpirometry patterns can suggest that a patient has a restrictive ventilatory impairment; however, lung volume measurements such as total lung capacity (TLC) are required to confirm the diagnosis. The aim of the study was to train a supervised machine learning model that can accurately estimate TLC values from spirometry and subsequently identify which patients would most benefit from undergoing a complete pulmonary function test.MethodsWe trained three tree-based machine learning models on 51,761 spirometry data points with corresponding TLC measurements. We then compared model performance using an independent test set consisting of 1,402 patients. The best-performing model was used to retrospectively identify restrictive ventilatory impairment in the same test set. The algorithm was compared against different spirometry patterns commonly used to predict restriction.ResultsThe prevalence of restrictive ventilatory impairment in the test set is 16.7% (234/1402). CatBoost was the best-performing machine learning model. It predicted TLC with a mean squared error (MSE) of 560.1 mL. The sensitivity, specificity, and F1-score of the optimal algorithm for predicting restrictive ventilatory impairment was 83, 92, and 75%, respectively.ConclusionA machine learning model trained on spirometry data can estimate TLC to a high degree of accuracy. This approach could be used to develop future smart home-based spirometry solutions, which could aid decision making and self-monitoring in patients with restrictive lung diseases.

Introduction: Gaseous air pollutants can cause oxidative stress, which can lead to lung damage by inducing inflammation. Polymorphisms in the glutathione S-transferase (GST) gene are involved in the pathogenesis of many diseases, including lung disease. Two glutathione S-transferase Mu 1 (GSTM1) and glutathione S-transferase theta 1 (GSTT1) genes belong to this family, in which deletions occur and the resulting alleles are unable to produce active enzymes. Materials and Methods: In this study, 41 steel plant workers with impaired lung function were selected. Multiplex PCR technique was used to identify the genotyping of GST M1 and T1. Results: The results of the frequency of gene deletion among 41 patients showed that there were 10 individuals (17.2%) with deletion of GSTM1 gene, 4 individuals (11.8%) with deletion of GSTT1 gene. The results of the frequency of gene deletion among 50 healthy individuals (control group) also showed that there were 8 individuals (8.5%) with deletion of GSTM1 gene, and 12 individuals (8.3%) with deletion of GSTT1 gene. There were 7 individuals (14%) without deletion of GSTM1 and GSTT1 removal. The results of Chi-square test between healthy and sick groups showed no significance at the level of p < 0.05. Conclusion: According to the results, it can be concluded that the sensitivity to lung function abnormalities in steel workers is directly related to the duration of employment.

Purpose To examine the effect of lung volume on the size and volume of pulmonary subsolid nodules (SSNs) measured on CT. Materials and Methods A total of 42 SSNs from 31 patients were included. CT examination was first performed at total lung capacity (TLC), and a section containing the nodule was additionally scanned at tidal volume (TV). The diameter and volume of each SSN, as well as the crosssectional lung area containing the nodule, were measured. The significance of the changes in measurements between TLC and TV within the same individuals was evaluated. Results The lung area and the diameter and volume of SSNs decreased significantly at TV by 12.7 cm2, 0.5 mm, and 46.4 mm3 on average, respectively (p < 0.001), compared to those at TLC. Changes in lung area between TV and TLC were positively correlated with the change in SSN diameter (p = 0.027) and volume (p = 0.014). However, after correction (by considering the change in lung area), the changes in SSN diameter (p = 0.124) and volume (p = 0.062) were not significantly different. Conclusion SSN size and volume can be significantly affected by lung volume during CT scans of the same individuals.

Background: Some evidences have shown the association between air pollution exposure and the development of interstitial lung diseases. However, the effect of air pollution on the progression of restrictive ventilatory impairment and diffusion capacity reduction is unknown. This study aimed to evaluate the effects of long-term exposure to ambient air pollution on the change rates of total lung capacity, residual volume, and diffusion capacity among the elderly.Methods: From 2016 to 2018, single-breath helium dilution with the diffusion capacity of carbon monoxide was performed once per year on 543 elderly individuals. Monthly concentrations of ambient fine particulate matters (PM2.5) and nitric dioxide (NO2) at the individual residential address were estimated using a hybrid Kriging/Land-use regression model. Linear mixed models were used to evaluate the association between long-term (12 months) exposure to air pollution and lung function with adjustment for potential covariates, including basic characteristics, indoor air pollution (second-hand smoke, cooking fume, and incense burning), physician diagnosed diseases (asthma and chronic airway diseases), dusty job history, and short-term (lag one month) air pollution exposure.Results: An interquartile range (5.37 ppb) increase in long-term exposure to NO2 was associated with an additional rate of decline in total lung volume (- 1.8% per year, 95% CI: - 2.8 to - 0.9%), residual volume (- 3.3% per year, 95% CI: - 5.0 to - 1.6%), ratio of residual volume to total lung volume (- 1.6% per year, 95% CI: - 2.6 to - 0.5%), and diffusion capacity (- 1.1% per year, 95% CI: - 2.0 to - 0.2%). There is no effect on the transfer factor (ratio of diffusion capacity to alveolar volume). The effect of NO2 remained robust after adjustment for PM2.5 exposure.Conclusions: Long-term exposure to ambient NO2 is associated with an accelerated decline in static lung volume and diffusion capacity in the elderly. NO2 related air pollution may be a risk factor for restrictive lung disorders. [ABSTRACT FROM AUTHOR]

Background: Idiopathic Pulmonary Fibrosis (IPF) is a progressive fibrotic lung disease. However, the field of quantitative CT scan analysis in conjunction with pulmonary function test for IPF patients remains relatively understudied. In this study, we evaluated the diagnostic value of features derived high-resolution computed tomography (HRCT) for patients with IPF and correlated them with pulmonary function tests., Methods: We retrospectively analyzed the chest HRCT images and pulmonary function test results of 52 patients with IPF during the same period (1 week) and selected 52 healthy individuals, matched for sex, age, and body mass index (BMI) and with normal chest HRCT as controls. HRCT scans were performed using a Philips 256-row Brilliance iCT scanner with standardized parameters. Lung function tests were performed using a Jaeger volumetric tracer for forced vital capacity (FVC), total lung capacity (TLC), forced expiratory volume in first second (FEV1), FEV1/FVC, carbon monoxide diffusing capacity (DLCO), and maximum ventilation volume (MVV) metrics. CT quantitative analysis, including tissue segmentation and threshold-based quantification of lung abnormalities, was performed using 3D-Slicer software to calculate the percentage of normal lung areas (NL%), percentage of ground-glass opacity areas (GGO%), percentage of fibrotic area (F%) and abnormal lesion area percentage (AA%). Semi-quantitative analyses were performed by two experienced radiologists to assess disease progression. The aortic-to-sternal distance (ASD) was measured on axial images as a standardized parameter. Spearman or Pearson correlation analysis and multivariate stepwise linear regression were used to analyze the relationship between the data in each group, and the ROC curve was used to determine the optimal quantitative CT metrics for identifying IPF and controls., Results: ROC curve analysis showed that F% distinguished the IPF patient group from the control group with the largest area under the curve (AUC) of 0.962 (95% confidence interval: 0.85-0.96). Additionally, with F% = 4.05% as the threshold, the Youden's J statistic was 0.827, with a sensitivity of 92.3% and a specificity of 90.4%. The ASD was significantly lower in the late stage of progression than in the early stage (t = 5.691, P < 0.001), with a mean reduction of 2.45% per month. Quantitative CT indices correlated with all pulmonary function parameters except FEV1/FVC, with the highest correlation coefficients observed for F% and TLC%, FEV1%, FVC%, MVV% (r = - 0.571, - 0.520, - 0.521, - 0.555, respectively, all P-values < 0.001), and GGO% was significantly correlated with DLCO% (r = - 0.600, P < 0.001). Multiple stepwise linear regression analysis showed that F% was the best predictor of TLC%, FEV1%, FVC%, and MVV% (R 2  = 0.301, 0.301, 0.300, and 0.302, respectively, all P-values < 0.001), and GGO% was the best predictor of DLCO% (R 2  = 0.360, P < 0.001)., Conclusions: Quantitative CT analysis can be used to diagnose IPF and assess lung function impairment. A decrease in the ASD may indicate disease progression., (© 2024. The Author(s).)

Introduction: Whole-body plethysmography is the preferred method for measuring the static lung volumes: total lung capacity (TLC), functional residual capacity (FRC) and residual volume (RV), as it also incorporates trapped gas - a common finding in chronic obstructive pulmonary disease (COPD). Quantitative computed tomography (CT) is a promising alternative to plethysmography, which can be challenging to perform for patients with severely impaired lung function. The present systematic review explores the agreement between lung volumes measured by plethysmography and CT, as well as the attempts being made to optimize alignment between these two methods., Methods: A literature search was performed on the PubMed database using the block search strategy. Articles were included if they provided both CT based and plethysmography based TLC. Risk of bias was evaluated using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) checklist., Results: 22 articles were included. On average, CT-derived TLC (CT-TLC) was 709 mL lower compared to plethysmography TLC (p-TLC) with a 12.1% deviation from the reference standard, p-TLC. This discrepancy (ΔTLC) appeared slightly larger in obstructive patients (obstructive: 781 mL, non-obstructive: 609 mL), whereas percent deviation was slightly smaller (obstructive: 11.4%, non-obstructive: 13.5%). CT-based RV analyses primarily based on COPD patients measured 603 mL higher than plethysmography (p-RV) with 17.8% deviation from p-RV. Studies utilizing spirometry-gating for CT acquisition reported good agreement between modalities (ΔTLC: 70-280 mL), and one study demonstrated noticeable improvements compared to conventional breath-hold instructions in an otherwise identical study setting., Conclusion: CT quantifications routinely underestimate TLC and overestimate RV in comparison to plethysmography. Spirometry gating reduces the level of disagreement and can be of assistance when patients are already undergoing CT. However, further studies are needed to confirm these results., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Purpose: The present study aimed to investigate the clinical characteristics and lung function impairment in young people diagnosed with chronic obstructive pulmonary disease (COPD)., Patients and Methods: We retrospectively enrolled patients with COPD who underwent symptom assessment and comprehensive pulmonary function tests at the First Affiliated Hospital of Guangzhou Medical University between August 2017 and March 2022. The patients were categorized into two groups based on age: a young COPD group (aged 20-50 years) and an old COPD group (aged > 50 years)., Results: A total of 1282 patients with COPD were included in the study, with 76 young COPD patients and 1206 old COPD patients. Young COPD patients exhibited a higher likelihood of being asymptomatic, lower rates of smoking, and a lower smoking index compared to old COPD patients. Although young COPD patients had higher median post-bronchodilator forced expiratory volume in 1 s (post-BD FEV 1 ) (1.4 vs.1.2 L, P = 0.019), diffusing capacity of the lung for carbon monoxide (D L CO) (7.2 vs. 4.6, P<0.001), and a lower median residual volume to total lung capacity ratio (RV/TLC) compared to their older counterparts, there were no differences observed in severity distribution by GOLD categories or the proportion of lung hyperinflation (RV/TLC%pred > 120%) between two groups. Surprisingly, the prevalence of reduced D L CO was found to be 71.1% in young COPD, although lower than in old COPD (85.2%)., Conclusion: Young COPD showed fewer respiratory symptoms, yet displayed a similar severity distribution by GOLD categories. Furthermore, a majority of them demonstrated lung hyperinflation and reduced D L CO. These results underscore the importance of a comprehensive assessment of lung function in young COPD patients., (© 2024. The Author(s).)

Background: In advanced chronic obstructive pulmonary disease (COPD), hypercapnia may occur due to severe bronchial obstruction with lung hyperinflation. Non-invasive ventilation (NIV) provides the standard of care intended to achieve physiological PCO 2 levels, thereby reducing overall mortality. The present study aimed to evaluate pulmonary function parameters derived from spirometry (forced vital capacity [FVC], forced expiratory volume in 1 s [FEV1]), body plethysmography (residual volume [RV], total lung capacity [TLC]), and lung diffusion capacity for carbon monoxide (single-breath method [DCO-SB], alveolar-volume corrected values [DCO-VA]) as predictors of chronic hypercapnia in patients with advanced COPD., Methods: This monocentric, retrospective observational study included 423 COPD patients. Receiver operating characteristic (ROC) curve analysis and cross-validation were used to assess lung function parameters' diagnostic accuracy for predicting chronic hypercapnia, with the resulting performance expressed as area under the ROC curve (AUROC). We performed univariable and multivariable binary logistic regression analysis to determine if these parameters were independently associated with chronic hypercapnia, with probabilities reported as odds ratios [OR] with 95% confidence intervals [95%CI]., Results: FVC% (AUROC 0.77 [95%CI 0.72-0.81], P < 0.01) and FEV1% (AURIC 0.75 [95%CI 0.70-0.79], P < 0.01) exhibited reasonable accuracy in the prediction of chronic hypercapnia, whereas lung diffusion capacity performed poorly (AUROC 0.64 [95%CI 0.58-0.71] for DCO-SB%, P < 0.01). FVC% (OR 0.95 [95%CI 0.93-0.97], P < 0.01) and FEV1% (OR 0.97 [95%CI 0.94-0.99], P = 0.029) were the only parameters associated independently with chronic hypercapnia in logistic regression analysis. FVC and FEV1 thresholds that best separated hypercapnic from normocapnic subjects reached 56% and 33% of predicted values., Conclusions: Routinely collected pulmonary function parameters, particularly FVC% and FEV1%, may predict chronic hypercapnia during COPD progression., (© 2024. The Author(s).)

Background: Restrictive lung function may indicate various underlying diseases. The aim of this study was to evaluate the accuracy of different restrictive spirometry patterns (RSPs) to identify restrictive lung function (total lung capacity [TLC] < lower limit of normal [LLN]) according to reference values by the Global Lung Function Initiative (GLI) in a wide age‐ranged, general population sample. Methods: A general population sample (n = 607, age 23–72 years, smokers 18.8%) with proper dynamic spirometry and TLC measurements, was included. Accuracy of two main categories of RSP to identify TLC < LLN were evaluated: traditional RSPs (definition 1: FVC < 80% of predicted and FEV1/FVC ≥ 0.7 and definition 2: FVC < LLN and FEV1/FVC ≥ LLN) and RSPs defined by Youden's method (definition 3: FVC < 85.5% of predicted and FEV1/FVC ≥ LLN and definition 4: FVC Z‐score < −1.0 and FEV1/FVC ≥ LLN). Results: The prevalence of restrictive lung function (TLC < LLN) was 5.3%. The most accurate cut‐offs for FVC to identify TLC < LLN were 85.5% for FVC% of predicted, and −1.0 for FVC Z‐score. The traditional RSP definitions 1 and 2 had higher specificity (95.0% and 96.9%) but substantially lower sensitivity compared to RSP definitions 3 and 4. Conclusion: Based on the GLI reference values, the RSP definition FVC < LLN and FEV1/FVC ≥ LLN yielded the highest specificity and may appropriately be used to rule out restrictive lung function. The RSP definition with the most favourable trade‐off between sensitivity and specificity, FVC < 85.5% of predicted and FEV1/FVC ≥ LLN, may serve as an alternative with higher sensitivity for screening. [ABSTRACT FROM AUTHOR]

Background/Aims Air trapping is associated with unfavorable outcomes in chronic obstructive pulmonary disease (COPD). The present study evaluated the association between longitudinal changes in air trapping with pulmonary function, computed tomography (CT) parameters and exacerbation. Methods Patients enrolled in the Korean Obstructive Lung Disease (KOLD) study cohort from June 2005 to October 2015 were included. The study patients were categorized into four groups according to the change in residual volume to total lung capacity ratio (RV/TLC) over 3 years. The RV/TLC was considered abnormal when it was ≥ 40% and normal when it was < 40%. Results A total of 279 patients were categorized into four groups: 76 in the “normal to normal” (N→N) group, 34 in the “abnormal to normal” (A→N) group, 33 in the “normal to abnormal” (N→A) group, and 136 in the “abnormal to abnormal” (A→A) group. For forced expiratory volume in 1 second and forced vital capacity (FVC), respectively, group A→N showed a large increase of 266 mL (p < 0.001) and 381 mL (p < 0.001), group N→A showed a marked decrease of 216 mL (p < 0.001) and 332 mL(p = 0.029), and group A→A showed a decrease of 16 mL (p = 0.426) and 6 mL (p = 0.011) compared to group N→N. Group A→N showed a significant decrease of −0.013 in expiratory to inspiratory ratio of the mean lung density (p < 0.001), while group A→N showed an increase of 0.005 (p < 0.001). Conclusions Patients with COPD whose RV/TLC changed from normal to abnormal showed deterioration of pulmonary function and worsening of CT parameters simultaneously.

Abstract Introduction: The aim of this study was to evaluate the delayed chest closure (DCC) results in patients who underwent lung transplantation. Methods: Sixty patients were evaluated retrospectively. Only bilateral lung transplantations and DCC for oversized lung allograft (OLA) were included in the study. Six patients who underwent single lung transplantation, four patients who underwent lobar transplantation, two patients who underwent retransplantation, and four patients who underwent DCC due to bleeding risk were excluded from the study. Forty-four patients were divided into groups as primary chest closure (PCC) (n=28) and DCC (n=16). Demographics, donor characteristics, and operative features and outcomes of the patients were compared. Results: The mean age was 44.5 years. There was no significant difference between the demographics of the groups (P>0.05). The donor/recipient predicted total lung capacity ratio was significantly higher in the DCC group than in the PCC group (1.06 vs. 0.96, P=0.008). Extubation time (4.3 vs. 3.1 days, P=0.002) and intensive care unit length of stay (7.6 vs. 5.2 days, P=0.016) were significantly higher in the DCC group than in the PCC group. In the DCC group, postoperative wound infection was significantly higher than in the PCC group (18.6% vs. 0%, P=0.19). Median survival was 14 months in all patients and there was no significant difference in survival between the groups (16 vs. 13 months, P=0.300). Conclusion: DCC is a safe and effective method for the management of OLA in lung transplantation.

Background and AimsAir trapping is a predictive index for a decline in lung function and mortality in patients with chronic obstructive pulmonary disease (COPD). However, the role of air trapping in COPD exacerbation has rarely been studied. Therefore, this study aimed to investigate the impact of air trapping as a continuous parameter on COPD exacerbation.Materials and MethodsTo evaluate air trapping, we identified the ratio of residual volume (RV) to total lung capacity (TLC) of patients with COPD from the Korean COPD Subgroup Study (KOCOSS) cohort, which is a multicenter-based, prospective, consecutive cohort in Korea. The primary outcome was a development of COPD exacerbation during 3 years of follow-up.ResultsOf 2,181 participants, 902 patients measured the RV/TLC ratio in the baseline enrollment, and 410 were evaluated for assessing the development of COPD exacerbation. Of 410 patients, the rate of moderate to severe exacerbation and severe exacerbation was 70.7% and 25.9%. A 10% increase of RV/TLC ratio increased the risk of the moderate to severe exacerbation by 35% and severe exacerbation by 36%. In subgroup analysis, an interaction effect between triple inhaled therapy and the RV/TLC ratio for severe exacerbation nullified the association between the RV/TLC ratio and severe exacerbation (p for interaction = 0.002).ConclusionsIn this prospective cohort study, we found that air trapping (representing RV/TLC ratio as a continuous parameter) showed an association with an increased risk of COPD exacerbation, particularly in patients who have not undergone triple inhaler therapy.

Introduction: The aim of this study was to evaluate the delayed chest closure (DCC) results in patients who underwent lung transplantation. Methods: Sixty patients were evaluated retrospectively. Only bilateral lung transplantations and DCC for oversized lung allograft (OLA) were included in the study. Six patients who underwent single lung transplantation, four patients who underwent lobar transplantation, two patients who underwent retransplantation, and four patients who underwent DCC due to bleeding risk were excluded from the study. Forty-four patients were divided into groups as primary chest closure (PCC) (n=28) and DCC (n=16). Demographics, donor characteristics, and operative features and outcomes of the patients were compared. Results: The mean age was 44.5 years. There was no significant difference between the demographics of the groups (P>0.05). The donor/recipient predicted total lung capacity ratio was significantly higher in the DCC group than in the PCC group (1.06 vs. 0.96, P=0.008). Extubation time (4.3 vs. 3.1 days, P=0.002) and intensive care unit length of stay (7.6 vs. 5.2 days, P=0.016) were significantly higher in the DCC group than in the PCC group. In the DCC group, postoperative wound infection was significantly higher than in the PCC group (18.6% vs. 0%, P=0.19). Median survival was 14 months in all patients and there was no significant difference in survival between the groups (16 vs. 13 months, P=0.300). Conclusion: DCC is a safe and effective method for the management of OLA in lung transplantation. [ABSTRACT FROM AUTHOR]

Total lung capacity is usually measured by a body plethysmograph or helium dilution methods. In this study an alternative approach to obtain total lung capacity of spontaneous breathing subjects is introduced. The device utilises an optoelectronic plethysmograph and a small tube, which measures mouth pressure and allows total lung capacity to be obtained, which differs less than 0.4 L from the total lung capacity of the body plethysmograph. The method shows potential to be a less burdensome method to estimate total lung capacity determination than the body plethysmograph.

Abstract Objective: To verify the concurrent validity between the inspiratory muscle strength (IMS) values obtained in static (maximal inspiratory pressure [MIP]) and dynamic (S-Index) assessments. Methods: Healthy individuals were submitted to two periods of evaluation: i) MIP, static maneuver to obtain IMS, determined by the Mueller’s maneuver from residual volume (RV) until total lung capacity (TLC); ii) and S-Index, inspiration against open airway starting from RV until TLC. Both measures were performed by the same evaluator and the subjects received the same instructions. Isolated maneuvers with differences < 10% were considered as reproducible measures. Results: Data from 45 subjects (21 males) were analyzed and that showed statistical difference between MIP and S-Index values (133.5 ± 33.3 and 125.6 ± 32.2 in cmH2O, respectively), with P=0.014. Linear regression showed r2=0.54 and S-Index prediction formula = 39.8+(0.75×MIP). Pearson’s correlation demonstrated a strong and significant association between the measures with r=0.74. The measurements showed good concordance evidenced by the Bland-Altman test. Conclusion: S-Index and MIP do not present similar values since they are evaluations of different events of the muscular contraction. However, they have a strong correlation and good agreement, which indicate that both are able to evaluate the IMS of healthy individuals.

Size-matching donors to recipients in lung transplantation continues to be a clinical challenge. Predicted total lung capacity equations, or more simply, donor and recipient heights, while widely used, are imprecise and may not be representative of the pool of donors and recipients. These inherent limitations may result in size discrepancies. The advent of easily accessible software and the widespread availability of computed tomography (CT) imaging in donor assessments have made it possible to directly measure lung volumes in donors and recipients. As a result, there is a growing interest in adopting personalized CT volumetry as an alternative. This article explores both methods and underscores the potential benefits and precision offered by CT., Competing Interests: Declaration of competing interest The authors of this manuscript have no conflicts of interest to disclose, as described by the American Journal of Transplantation., (Copyright © 2024 American Society of Transplantation & American Society of Transplant Surgeons. Published by Elsevier Inc. All rights reserved.)

Back Ground: Knowledge concerning pulmonary function in adult patients with onset of idiopathic scoliosis before age 10 is sparse. A long-term follow-up (FU, mean 26 years, > 12 years after treatment) of pulmonary function (PF) in patients treated with brace or surgery due to idiopathic scoliosis with onset before the age of 10 was earlier performed. To evaluate whether a more severe reduction in pulmonary function leads to more rapid deterioration within a four-year period, this study was performed., Methods: Twenty patients with the most reduced pulmonary function and 19 out of those with normal PF found at the long-term FU were reexamined 4 years later to evaluate further changes in pulmonary function. Patients underwent spirometry and arterial blood gas analysis and answered pulmonary symptom questionnaires., Results: 70% of the reduced pulmonary function group had undergone surgery vs. 26% of the normal group. The mean age (47 vs. 43 years) at this FU and curve size (37° vs. 35°) at the 26-year FU were similar. The decline in forced vital capacity (FVC) % of predicted was similar in both groups over the four-year period, from 67 to 65% in the reduced PF group vs. 96 to 94% in the normal PF group. The total lung capacity (TLC) % of predicted did not change over time in either group. No patient reported worsening dyspnea symptoms. Only one patient in the reduced PF group showed low arterial oxygen tension, 8.4 kPa, not signifying respiratory insufficiency., Conclusion: The age-related decline in FVC and TLC % of predicted did not differ between those with reduced and those with normal pulmonary function at the 26-year follow-up. Thus, these data do not infer increased rate of decline in the most deteriorated patients., (© 2024. The Author(s).)

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)., (© 2024. The Author(s).)

Background: Whole-body plethysmography (WBP) is the gold standard for measuring lung volume, but its clinical application is limited as it requires expensive equipment and is not simple to use. Studies have shown that the single-breath helium dilution (SBHD) method, which is commonly used in clinical practice, significantly underestimates lung volume in patients with obstructive lung disease (OLD). By comparing the differences in lung volume measured using SBHD and WBP, we aimed to establish a correction equation for the SBHD method to determine the total lung volume in patients with OLD of different severities.Methods: From 628 patients with OLD simultaneously subjected to SBHD and WBP, 407 patients enrolled between January 2018 and November 2019 were in the training group and 221 enrolled between December 2019 and December 2020 were in the prospective verification cohort. The multiple linear regression equation was used for data in the training group to establish a correction equation for SBHD to determine the total lung volume, and this was validated in the prospective validation cohort.Results: There was a moderate positive correlation between total lung capacity (TLC) determined using the SBHD [TLC (SBHD)] and WBP methods [TLC (WBP)] (r = 0.701; P < 0.05), and the differences between TLC (SBHD) and TLC (WBP) (ΔTLC) were related to the severity of obstruction. As the severity of obstruction increased, the TLC was underestimated by the SBHD method. We established the following correction equation: TLC (adjusted SBHD) (L) = −0.669 + 0.756*TLC(SBHD)(L) – 0.047*FEV1FVC+0.039*height (cm)–0.009*weight(kg)(r2 = 0.753 and adjusted r2 = 0.751). Next, we validated this equation in the validation cohort. With the correction equation, no statistical difference was observed between TLC (adjusted SBHD) and TLC (WBP) among the obstruction degree groups (P > 0.05).Conclusions: The SBHD method is correlated with WBP to measure the total lung volume, but the SBHD method presents limitations in determining the total lung volume in patients with obstructive lung disease. Here, we established an effective and reliable correction equation in order to accurately assess the total lung volume of patients with OLD using the SBHD method.

Background: Current techniques for measuring absolute lung volumes rely on bulky and expensive equipment and are complicated to use for the operator and the patient. A novel method for measurement of absolute lung volumes, the MiniBox method, is presented.Research Question: Across a population of patients and healthy participants, do values for total lung capacity (TLC) determined by the novel compact device (MiniBox, PulmOne Advanced Medical Devices, Ltd.) compare favorably with measurements determined by traditional whole body plethysmography?Study Design and Methods: A total of 266 participants (130 men) and respiratory patients were recruited from five global centers (three in Europe and two in the United States). The study population comprised individuals with obstructive (n = 197) and restrictive (n = 33) disorders as well as healthy participants (n = 36). TLC measured by conventional plethysmography (TLCPleth) was compared with TLC measured by the MiniBox (TLCMB).Results: TLC values ranged between 2.7 and 10.9 L. The normalized root mean square difference (NSD) between TLCPleth and TLCMB was 7.0% in healthy participants. In obstructed patients, the NSD was 7.9% in mild obstruction and 9.1% in severe obstruction. In restricted patients, the NSD was 7.8% in mild restriction and 13.9% in moderate and severe restriction. No significant differences were found between TLC values obtained by the two measurement techniques. Also no significant differences were found in results obtained among the five centers.Interpretation: TLC as measured by the novel MiniBox system is not significantly different from TLC measured by conventional whole body plethysmography, thus validating the MiniBox method as a reliable method to measure absolute lung volumes. [ABSTRACT FROM AUTHOR]

The coronavirus disease (COVID-19) pandemic has already affected millions of individuals, with increasing numbers of survivors. These data suggest that the pulmonary sequelae of the infection may have an effect on a wide range of individuals. The aim of the present study was to evaluate pulmonary function in patients hospitalized due to COVID-19 three months after hospital discharge. A total of 116 patients, 34 females and 82 males, with a mean age of 57.77±11.45 years, who were hospitalized due to COVID-19, underwent pulmonary function testing three months after their hospital discharge. Of these, 83 (71.6%) patients were hospitalized in the period of alpha variant predominance, 16 (13.8%) in the period of delta variant predominance and 17 (14.6%) in the omicron variant predominance period. The mean value of diffusion capacity for carbon monoxide (DLCO)% predicted (pred) was statistically higher in patients affected by the omicron variant (P=0.028). Abnormal values (<80% pred) of DLCO and total lung capacity (TLC) were observed in 28.4 and 20.7% of the patients, respectively. Active smoking was an independent predictor of abnormal values of forced expiratory volume in 1 sec % pred and TLC% pred [P=0.038; odds ratio (OR): 8.574, confidence interval (CI) 1.124-65.424 and P=0.004, OR: 14.733, CI 2.323-93.429, respectively], age was an independent predictor of abnormal values of forced vital capacity % pred and DLCO% pred (P=0.027, OR: 1.124, CI 1.014-1.246 and P=0.011, OR:1.054, CI 1.012-1.098, respectively); and female sex was an independent predictor of abnormal values of DLCO% pred (P=0.009, OR: 1.124, CI 1.014-1.246). Α significant percentage of hospitalized patients due to COVID-19 pneumonia will develop abnormal pulmonary function, regardless of the SARS-CoV-2 variant. [ABSTRACT FROM AUTHOR]

Background: The 2017 ATS/ERS technical standard for measuring the single-breath diffusing capacity (DLCO) proposed the "rapid-gas-analyzer" (RGA) or, equivalently, "total-breath" (TB) method for the determination of total lung capacity (TLC). In this study, we compared DLCO and TLC values estimated using the TB and conventional method, and how estimated TLC using these two methods compared to that determined by body plethysmography., Method: A total of 95 people with COPD (GOLD grades 1-4) and 23 healthy subjects were studied using the EasyOne Pro (ndd Medical Technologies, Switzerland) and Master Screen Body (Vyaire Medical, Höchberg, Germany)., Results: On average the TB method resulted in higher values of DLCO (mean ± SD Δ = 0.469 ± 0.267; 95%CI: 0.420; 0.517 mmol*min-1*kPa-1) and TLC (Δ = 0.495 ± 0.371; 95%CI: 0.427; 0.562 L) compared with the conventional method. In healthy subjects the ratio between TB and conventional DLCO was close to one. TLC estimated using both methods was lower than that determined by plethysmography. The difference was smaller for the TB method (Δ = 1.064 ± 0.740; 95%CI: 0.929; 1.199 L) compared with the conventional method (Δ = 1.558 ± 0.940; 95%CI: 1.387; 1.739 L). TLC from body plethysmography could be estimated as a function of TB TLC and FEV 1 Z-Score with an accuracy (normalized root mean square difference) of 9.1%., Conclusion: The total-breath method yielded higher values of DLCO and TLC than the conventional analysis, especially in subjects with COPD. TLC from the total-breath method can also be used to estimate plethysmographic TLC with better accuracy than the conventional method. The study is registered under clinicaltrial.gov NCT04531293., (© 2024. The Author(s).)

Background: Lung hyperinflation is a typical clinical feature of patients with COPD. Given the association between breathing at elevated lung volumes and the manifestation of severe debilitating symptoms, therapeutic interventions such as positive expiratory pressure (PEP) therapy and its variations (temporary, oscillatory) have been devised to mitigate lung hyperinflation. However, the efficacy of these interventions remains to be conclusively demonstrated., Methods: A systematic review with meta-analysis of randomized trials was conducted following the PRISMA guidelines. Seven databases were screened with no date or language restriction. Two authors independently applied eligibility criteria and assessed the risk of bias of included studies using the Cochrane risk-of-bias tool. Outcomes were lung hyperinflation measures detected through changes in inspiratory capacity (IC), functional residual capacity (FRC), total lung capacity (TLC), and residual volume (RV), as well as FEV 1 , FVC, dyspnea, and physical capacity. Pooled standardized mean differences (SMDs) or mean differences (MDs) and 95% CI were calculated using a random-effects model., Results: Seven trials, all with a high risk of bias, were included. Compared to control group, RV significantly decreased (4 studies, n = 231; SMD -0.42 [95% CI -0.77 to -0.08], P = .02), dyspnea improved ( n = 321, SMD -1.17 [95% CI -1.68 to -0.66], P < .001), and physical capacity increased (5 studies, n = 311; MD 30.1 [95% CI 19.2-41.0] m, P < .001) with PEP therapy. There was no significant difference between PEP therapy and the control group in TLC, FVC, or FEV 1 . Only one study reported changes in inspiratory capacity as well as FRC., Conclusions: In patients with COPD, the effect of PEP therapy on lung hyperinflation is unclear owing to the non-consistent change in lung hyperinflation outcomes, insufficient data, and lack of high-quality trials. Dyspnea and physical capacity might improve with PEP therapy., Competing Interests: The authors have disclosed no conflicts of interest., (Copyright © 2024 by Daedalus Enterprises.)

Background: Previous studies have shown that the ratio between alveolar volume (V A ) and total lung capacity (TLC) reflects ventilation heterogeneity in subjects with chronic obstructive pulmonary disease (COPD). However, the ratio and its correlation to respiratory symptoms had to our knowledge not previously been investigated in subjects with mild chronic airflow obstruction or without airflow obstruction (normal ratio FEV 1 /VC). The purpose of this study was to investigate potential connection between V A /TLC and respiratory symptoms, smoking habits and lung function parameters in subjects with normal spirometry and with mild chronic airflow obstruction., Methods: We examined 450 subjects (82 non-smokers with normal spirometry, 298 subjects who smoked or had smoked earlier but had a normal spirometry and 70 subjects with chronical airflow obstruction) with routine lung function tests and a questionnaire regarding respiratory symptoms., Results: This study showed 31 out of 54 subjects with a low V A /TLC had a normal ratio FEV 1 /VC. Of these subjects, 58.1 % had respiratory symptoms, compared to the group with normal ratio for both V A /TLC and FEV 1/ VC where 35.8 % had respiratory symptoms (p-value 0.02)., Conclusion: This study has shown that within the group of subjects with a normal ratio FEV 1 /VC, those with a decreased ratio V A /TLC had a higher prevalence of respiratory symptoms compared to subjects with a normal V A /TLC ratio. These findings indicate that including the ratio V A /TLC in the evaluation of a pulmonary function test assessment might increase the possibility to identify subjects with early or at risk of lung disease., Competing Interests: Declaration of competing interest The authors declare the following financial interests/ personal relationships which may be considered as potential competing interests: P Wollmer reports a relationship with Chiesi Pharma that includes consulting or advisory. P Wollmer has patent issued to Method and device for pulmonary function measurement., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: To evaluate the degree of lung hyperinflation (LH) in patients with stable chronic obstructive pulmonary disease (COPD) by lung ultrasound score (LUS) and assess its value., Patients and Methods: We conducted a study of 149 patients with stable COPD and 100 healthy controls recruited by the Second Affiliated Hospital of Fujian Medical University. The pleural sliding displacement (PSD) was measured, the sliding of the pleura in different areas was observed, and LUS was calculated from both of them. The diaphragm excursion (DE), residual capacity (RV), total lung capacity (TLC), inspiratory capacity (IC) and functional residual capacity (FRC) were measured. We described the correlation between ultrasound indicators and pulmonary function indicators reflecting LH. Multiple linear regression analysis was used. The ROC curves of LUS and DE were drawn to evaluate their diagnostic efficacy, and De Long method was used for comparison., Results: (1) The LUS of patients with stable COPD were positively correlated with RV, TLC, RV/TLC and FRC and negatively correlated with IC and IC/TLC ( r 1 =0.72, r 2 =0.41, r 3 =0.72, r 4 =0.70, r 5 =-0.56, r 6 =-0.65, P < 0.001). The correlation was stronger than that between DE at maximal deep inspiration and the corresponding pulmonary function indices ( r 1 =-0.41, r 2 =-0.26, r 3 =-0.40, r 4 =-0.43, r 5 =0.30, r 6 =0.37, P < 0.001). (2) Multiple linear regression analysis showed that LUS were significantly correlated with IC/TLC and RV/TLC. (3) With IC/TLC<25% and RV/TLC>60% as the diagnostic criterion of severe LH, the areas under the ROC curves of LUS and DE at maximal deep inspiration for diagnosing severe LH were 0.914 and 0.385, 0.845 and 0.543, respectively ( P < 0.001)., Conclusion: The lung ultrasound score is an important parameter for evaluating LH. LUS is better than DE at maximal deep inspiration for diagnosing severe LH and is expected to become an effective auxiliary tool for evaluating LH., Competing Interests: The authors declare that they have no competing interests in this work., (© 2024 Chen et al.)

Background: Effective use of lung volume data measured on computed tomography (CT) requires reference values for specific populations. This study examined whether an equation previously generated for multiple ethnic groups in the United States, including Asians predominantly composed of Chinese people, in the Multi-Ethnic Study of Atherosclerosis (MESA) could be used for Japanese people and, if necessary, to optimize this equation. Moreover, the equation was used to characterize patients with chronic obstructive pulmonary disease (COPD) and lung hyperexpansion., Methods: This study included a lung cancer screening CT cohort of asymptomatic never smokers aged ≥40 years from two institutions (n = 364 and 419) to validate and optimize the MESA equation and a COPD cohort (n = 199) to test its applicability., Results: In all asymptomatic never smokers, the variance explained by the predicted values (R 2 ) based on the original MESA equation was 0.60. The original equation was optimized to minimize the root mean squared error (RMSE) by adjusting the scaling factor but not the age, sex, height, or body mass index terms of the equation. The RMSE changed from 714 ml in the original equation to 637 ml in the optimized equation. In the COPD cohort, lung hyperexpansion, defined based on the 95th percentile of the ratio of measured lung volume to predicted lung volume in never smokers (122 %), was observed in 60 (30 %) patients and was associated with centrilobular emphysema and air trapping on inspiratory/expiratory CT., Conclusions: The MESA equation was optimized for Japanese middle-aged and elderly adults., Competing Interests: Declaration of competing interest N.T. and T.H. received research grants from Daiichi Sankyo and FUJIFILM Co., Ltd., outside of the submitted work. S.S. received grants from Nippon Boehringer Ingelheim, Philips-Respironics, Fukuda Denshi, Fukuda Lifetec Keiji, and ResMed outside of the submitted work. None of these companies played a role in the design or analysis of the study or the writing of the manuscript. The other authors have no conflicts of interest., (Copyright © 2023. Published by Elsevier B.V.)

Objective: To verify the concurrent validity between the inspiratory muscle strength (IMS) values obtained in static (maximal inspiratory pressure [MIP]) and dynamic (S-Index) assessments. Methods: Healthy individuals were submitted to two periods of evaluation: i) MIP, static maneuver to obtain IMS, determined by the Mueller’s maneuver from residual volume (RV) until total lung capacity (TLC); ii) and S-Index, inspiration against open airway starting from RV until TLC. Both measures were performed by the same evaluator and the subjects received the same instructions. Isolated maneuvers with differences < 10% were considered as reproducible measures. Results: Data from 45 subjects (21 males) were analyzed and that showed statistical difference between MIP and S-Index values (133.5 ± 33.3 and 125.6 ± 32.2 in cmH2O, respectively), with P=0.014. Linear regression showed r² =0.54 and S-Index prediction formula = 39.8+(0.75×MIP). Pearson’s correlation demonstrated a strong and significant association between the measures with r=0.74. The measurements showed good concordance evidenced by the Bland-Altman test. Conclusion: S-Index and MIP do not present similar values since they are evaluations of different events of the muscular contraction. However, they have a strong correlation and good agreement, which indicate that both are able to evaluate the IMS of healthy individuals. [ABSTRACT FROM AUTHOR]

Introduction: Pulmonary hypertension (PH) is a well-recognised complication of interstitial lung diseases (ILD), which worsens prognosis and impairs exercise capacity. Echocardiography is the most widely used, non-invasive method for PH assessment. The aim of our study was to identify the factors predictive for echocardiographic signs of PH in newly recognised ILD patients. Methods: Ninety-three consecutive patients (28F/65M) with different ILD were prospectively evaluated from January 2009 to March 2014. Pulmonary function testing, 6-min walk distance (6MWD), initial and sixth minute room air oxygen saturation, NT-proBNP and echocardiography were assessed in each patient. Echocardiographic PH probability was determined according to the 2009 ESC/ERS guidelines. Results: In 41 patients (Group B) increased PH possibility has been diagnosed on echocardiography, in 52 patients (Group A)—low PH probability. Most pronounced differences (p ≤ 0.0005) between groups B and A concerned: age, 6MWD, room air oxygen saturation at 6 min, DLCO and TLC/DLCO index (57.6 vs 43.8 years; 478 vs 583 m; 89.1% vs 93.4%; 54.8% predicted vs 70.5% predicted and 1.86 vs 1.44; respectively). Univariate analysis showed four-fold increased probability of PH when TLC/DLCO exceeded 1.67. A scoring system incorporating age, TLC/DLCO index, 6MWD and room air oxygen saturation at 6 min provided high diagnostic utility, AUC 0.867 (95% CI 0.792–0.867). Conclusion: ILD patients with TLC/DLCO index > 1.67 have a high likelihood of PH and should undergo further evaluation. The composite model of PH prediction, including age, 6-min walk test and TLC/DLCO was highly specific for recognition of PH on echocardiography. [ABSTRACT FROM AUTHOR]

CONTEXT: Lung hyperinflation is defined as an abnormal increase in the volume of air remaining in the lungs at the end of normal expiration caused by the permanently destructive changes of emphysema and expiratory flow limitation. All the rehabilitation exercise programs have some reinforcement on hyperinflation mechanism directly or indirectly without any associated feedback. AIMS: This study aims to study the effect of visual biofeedback training on lung hyperinflation in chronic obstructive pulmonary disease (COPD) patients. SUBJECTS AND METHODS: 104 mild to moderate (global initiative for chronic obstructive lung disease) COPD patient of age group 40-60 years were recruited and randomly allocated to control and experimental group using random reviewer software 3.3 versions. The baseline and postoutcomes were analyzed by an external observer who is blinded. The visual training group receives biofeedback training on expiratory flow limitation. Both experimental and control group receives aerobic exercise training of 50%-60% of maximum heart rate intensity where all received cycling as a mode for 20-40 min with a warm and cool-down period. All the patients were trained for 4 days a week for 8 weeks. STATISTICAL ANALYSIS USED: Descriptive statistics, independent sample t-test, and repeated measures of analysis of variance. RESULTS: Residual volume and total lung capacity significantly reduced statistics F = 12.23 with P < 0.001 between the group. Breath hold time and maximum expiratory pressure showed increase response with significant statistics of F = 8.53 with P < 0.05 between the group. CONCLUSION: Visual feedback exercise training is one of the effective training methods to relieve the hyperinflation in stable COPD patients thereby improves exercise tolerance and quality of life. [ABSTRACT FROM AUTHOR]

The aim was to evaluate the impact of multiple high-resolution computed tomography (HRCT) features on pulmonary function test (PFT) biomarkers in fibrotic interstitial lung disease (FILD) patients. HRCT of subsequently ILD-board-discussed FILD patients were semi-quantitatively evaluated in a standardized approach: 18 distinct lung regions were scored for noduli, reticulation, honeycombing, consolidations, ground glass opacities (GGO), traction bronchiectasis (BRK) and emphysema. Total lung capacity (TLC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC, diffusion capacity for carbon monoxide (DLCO) and transfer coefficient (KCO) were assessed. Interactions between each PFT biomarker and all HRCT scores were visualized by network analyses, modeled according to the Schwarz Bayesian Information Criterion and incorporated in uni- and multivariate stepwise regression analyses. Among 108 FILD patients (mean age 67 years, 77% male), BRK extent was a major significant uni- or multivariate determinant of all PFT analyzed. Besides that, diffusion-based variables DLCO and KCO showed a larger dependency on reticulation, emphysema and GGO, while forced expiratory volume-based measures FEV1, FVC and FEV1/FVC were more closely associated with consolidations. For TLC, the only significant multivariate determinant was reticulation. In conclusion, PFT biomarkers derived from spirometry, body plethysmography and diffusion capacity in FILD patients are differentially influenced by semi-quantified HRCT findings. [ABSTRACT FROM AUTHOR]

Abstract The small airways of the lungs are commonly affected in pediatric and adult asthma. Small airways disease has been related to asthma control, severity, and risk of exacerbation. Diagnosis of small airways disease can be best made through evaluation of surgical lung specimens. Noninvasive techniques including spirometry, plethysmography, nitrogen washout, impulse oscillometry, and cross-sectional imaging have been utilized to assess and infer the extent of small airways disease in asthma and can be used longitudinally to assess response to treatment. Patients with small airways disease seem to benefit from inhaled asthma medications that have improved capacity to reach the distal lung compartment. This is especially important for patients with severe asthma, who rely upon high doses of inhaled corticosteroid and bronchodilators for asthma control. This review will describe the techniques which may be utilized to assess small airways disease, discuss the prevalence and characteristics of small airways disease in severe asthma, and highlight how small airway disease may complicate severe asthma treatment.

Background: Current measures of tidal volume/forced vital capacity (VT/FVC) and VT/inspiratory capacity (VT/IC) at peak exercise cannot differentiate restrictive from obstructive ventilation patterns. This study aimed to investigate the utility of VT/total lung capacity (VT/TLC) as a marker for dynamic lung hyperinflation (DH) in patients with chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD)., Methods: 267 subjects were screened: 23 ILD, 126 COPD, and 33 healthy individuals were enrolled. Lung function tests and cardiopulmonary exercise tests with repeated IC maneuver were conducted and compared at three exercise efforts: unloaded, middle of exercise, and peak exercise., Results: During exercise, ILD patients demonstrated normal end-expiratory lung volume/TLC (EELV/TLC) ratios, but elevated end-inspiratory lung volume/TLC (EILV/TLC) ratios, except for peak exercise. COPD patients exhibited elevated ratios for both EELV/TLC and EILV/TLC during exercise with a larger EELV/TLC ratio compared to ILD patients at peak exercise (p < 0.05). The VT/TLC ratio distinguished ILD, COPD, and healthy controls at peak exercise (p < 0.05). A VT/TLC ratio of ≤ 0.22 or ≥ 0.30 indicated airflow obstruction with hyperinflation or normal lung expansion, respectively (AUC: 0.74 or 0.88). Furthermore, VT/TLC outperformed VT/FVC and VT/IC in differentiating lung expansion between ILD and COPD during exercise (all p < 0.05)., Conclusion: Exercise-induced DH was absent in ILD patients but observed in COPD patients. Excessive lung expansion occurred in all patients during exercise, except for limited expansion in ILD at peak exercise probably due to specific lung properties. VT/TLC can distinguish between restrictive, obstructive, and normal ventilatory patterns., Competing Interests: Declaration of Competing Interest The authors declare no competing interests., (Copyright © 2023. Published by Elsevier B.V.)

Purpose: Glucocorticoids are used to prevent chronic lung allograft dysfunction (CLAD) after lung transplantation (LT). Our study was aimed at assessing the association between the glucocorticoid-induced transcript 1 gene (GLCCI1) variant, which modulates glucocorticoid sensitivity, and the postoperative lung function and development of CLAD after LT.Methods: A total of 71 recipients of LT were genotyped for the GLCCI1 variant (rs37972) and divided into three groups: the homozygous mutant allele (TT) group, the heterozygous mutant allele (CT) group, and the wild-type allele (CC) group. The results of pulmonary function tests were compared with the postoperative baseline values.Results: The total lung capacity (TLC) in the TT group was significantly lower than that in the CC group at 3 years after LT (P = 0.029). In the recipients of cadaveric LT, the TLC and forced expiratory volume in 1 s in the TT group were significantly lower than those in the CC groups, resulting in a significant worse CLAD-free survival at 3 years after LT (P = 0.016).Conclusion: The GLCCI1 variant was associated with a significant decrease of the TLC at 3 years after LT and the development of CLAD at 3 years, especially in patients undergoing cadaveric LT. [ABSTRACT FROM AUTHOR]

The aim of the study was to investigate the relationship between slow and forced vital capacity (SVC-FVC) difference with dynamic lung hyperinflation (DH) during the 6-min walking test (6MWT) in subjects with chronic obstructive pulmonary disease (COPD). Twenty-four subjects with COPD (12 males; 67 ± 6 years; forced expiratory volume in first second [FEV1] 56 ± 18% predicted) performed lung function tests by spirometry and plethysmography. DH was assessed by serial measurements of inspiratory capacity (IC) performed during the 6MWT and defined as ∆IC ≥ 150 mL or 10%. IC decrease significantly during the 6MWT (ΔCI: − 0.48 ± − 0.40 L; P < 0.0001), and 18 individuals (75%) presented DH. There was significant difference when comparing IC measured at rest with the other serial IC measurements (P < 0.0001). Correlation between the SVC-FVC difference and DH during the 6MWT was r = − 0.38; P = 0.06. The SVC-FVC difference presented only weak correlation with the development of DH during the 6MWT in patients with COPD. [ABSTRACT FROM AUTHOR]

PURPOSE: To describe pulmonary function and determine the impact of neurological level, scoliosis, and obesity on pulmonary function in people with spina bifida (SB). METHODS: Participants with SB (N = 29) (15 females; age, 30 ± 12 years) completed spirometry and body plethysmographic lung volume testing. Univariate and multivariate regression analyses were used to describe the factors associated with pulmonary function in people with SB. RESULTS: Distribution of category of impairment in pulmonary function was: 55% (n = 16) restricted, 6.9% (n = 2) spirometric restricted, 1 combined obstructed and restricted, and 35.5% (n = 10) normal. In univariate analyses, neurological level was negatively associated with pulmonary function parameters, i.e., forced vital capacity (FVC) (p = 0.005), forced expiratory volume in 1 second (FEV 1) (p = 0.008), total lung capacity (TLC) (p = 0.001), and degree of scoliosis were inversely associated with FVC (p = 0.005), FEV 1 (p = 0.003), and TLC (p = 0.004). In multivariate models, level of lesion and degree of scoliosis independently contributed to the degree of lung function impairment. Restrictive pulmonary function was observed in 9/10 (90%) of those with thoracic neurological levels and was associated with decreased inspiratory capacity (IC) and expiratory reserve volume (ERV). Lumbar level lesions were associated with either normal lung function or an isolated reduction in FVC due to reduction in only ERV and preserved TLC representing spirometric restriction. CONCLUSIONS: High prevalence of restrictive pulmonary physiology is present in people with SB, with more rostral neurological levels and greater degree of scoliosis associated with a higher degree of pulmonary function impairment. [ABSTRACT FROM AUTHOR]

Diving mammals have evolved a suite of physiological adaptations to manage respiratory gases during extended breath-hold dives. To test the hypothesis that offshore bottlenose dolphins have evolved physiological adaptations to improve their ability for extended deep dives and as protection for lung barotrauma, we investigated the lung function and respiratory physiology of four wild common bottlenose dolphins (Tursiops truncatus) near the island of Bermuda. We measured blood hematocrit (Hct, %), resting metabolic rate (RMR, l O2 ⋅ min-1), tidal volume (VT, l), respiratory frequency (fR, breaths ⋅ min-1), respiratory flow (l ⋅ min-1), and dynamic lung compliance (CL, l ⋅ cmH2O-1) in air and in water, and compared measurements with published results from coastal, shallow-diving dolphins. We found that offshore dolphins had greater Hct (56 ± 2%) compared to shallow-diving bottlenose dolphins (range: 30–49%), thus resulting in a greater O2 storage capacity and longer aerobic diving duration. Contrary to our hypothesis, the specific CL (sCL, 0.30 ± 0.12 cmH2O-1) was not different between populations. Neither the mass-specific RMR (3.0 ± 1.7 ml O2 ⋅ min-1 ⋅ kg-1) nor VT (23.0 ± 3.7 ml ⋅ kg-1) were different from coastal ecotype bottlenose dolphins, both in the wild and under managed care, suggesting that deep-diving dolphins do not have metabolic or respiratory adaptations that differ from the shallow-diving ecotypes. The lack of respiratory adaptations for deep diving further support the recently developed hypothesis that gas management in cetaceans is not entirely passive but governed by alteration in the ventilation-perfusion matching, which allows for selective gas exchange to protect against diving related problems such as decompression sickness.

Sliding between lung lobes along lobar fissures is a poorly understood aspect of lung mechanics. The objective of this study was to test the hypothesis that lobar sliding helps reduce distortion in the lung parenchyma during breathing. Finite element models of left lungs with geometries and boundary conditions derived from medical images of human subjects were developed. Effect of lobar sliding was studied by comparing nonlinear finite elastic contact mechanics simulations that allowed and disallowed lobar sliding. Lung parenchymal distortion during simulated breath-holds and tidal breathing was quantified with the model's spatial mean anisotropic deformation index (ADI), a measure of directional preference in volume change that varies spatially in the lung. Models that allowed lobar sliding had significantly lower mean ADI (i.e., lesser parenchymal distortion) than models that disallowed lobar sliding under simulations of both tidal breathing (5.3% median difference, P = 0.008, n = 8) and lung deformation between breath-holds at total lung capacity and functional residual capacity (3.2% median difference, P = 0.03, n = 6). This effect was most pronounced in the lower lobe where lobar sliding reduced parenchymal distortion with statistical significance, but not in the upper lobe. In addition, more lobar sliding was correlated with greater reduction in distortion between sliding and nonsliding models in our study cohorts (Pearson's correlation coefficient of 0.95 for tidal breathing, 0.87 for breath-holds, and 0.91 for the combined dataset). These findings are consistent with the hypothesis that lung lobar sliding reduces parenchymal distortion during breathing. NEW & NOTEWORTHY The role of lobar sliding in lung mechanics is poorly understood. Delineating this role could help explain how breathing is affected by anatomical differences between subjects such as incomplete and missing lobar fissures. We used computational contact mechanics models of lungs from human subjects to delineate the effect of lobar sliding by comparing simulations that allowed and disallowed sliding. We found evidence consistent with the hypothesis that lung lobar sliding reduces parenchymal distortion during breathing.