Measurement Of Diffusing Capacity Research Articles

Resting diffusing capacity and severity of radiographic disease predict gas exchange abnormalities with exercise in former US coal miners.

The US Department of Labor (DOL) does not fund diffusing capacity (DLCO) or metabolic measurements from cardiopulmonary exercise testing (CPET) for coal miners' disability evaluations. Although exercise arterial blood gas testing is covered, many miners are unable to perform maximal tests, and sampling at peak exercise can be challenging. We explored the relationship between resting DLCO, radiographic disease severity, and CPET abnormalities in former US coal miners. We analyzed data from miners evaluated between 2005 and 2015. Multivariable linear and logistic regression analyses were used to examine relationships between percent predicted (pp) forced expiratory volume in 1 s (FEV1pp), DLCOpp, VO2maxpp, A-a oxygen gradient (A-a)pp, dead space fraction (Vd/Vt), disabling oxygen tension (PO2), and radiographic findings of pneumoconiosis. Data from 2015 male coal miners was analyzed. Mean tenure was 28 years (SD 8.6). Thirty-twopercent had an abnormal A-a gradient (>150 pp), 20% had elevated Vd/Vt (>0.33), and 34% a VO2max < 60 pp. DLCOpp strongly predicted a disabling PO2, with an odds ratio (OR) of 2.33 [2.09-2.60], compared to 1.18 [1.08-1.29] for FEV1. Each increase in subcategory of small opacity (simple) pneumoconiosis increased the odds of a disabling PO2 by 42% [1.29-1.57], controlling for age, body mass index, pack-years of tobacco smoke exposure, and years of coal mine employment. DLCO is the best resting pulmonary function test predictor of CPET abnormalities. Radiographic severity of pneumoconiosis was also associated with CPET abnormalities. These findings support funding DLCO testing for impairment and suggest the term "small opacity" should replace "simple" pneumoconiosis to reflect significant associations with impairment.

Dual Test Gas Pulmonary Diffusing Capacity Measurement During Exercise in Humans Using the Single-Breath Method.

The combined single-breath measurement of the diffusing capacity of carbon monoxide (DL,CO) and nitric oxide (DL,NO) is a useful technique to measure pulmonary alveolar-capillary reserve in both healthy and patient populations. The measurement provides an estimate of the participant's ability to recruit and distend pulmonary capillaries. The method has recently been reported to exhibit a high test-retest reliability in healthy volunteers during exercise of light to moderate intensity. Of note, this technique permits up to 12 repeated maneuvers and only requires a single breath with a relatively short breath-hold time of 5 s. Representative data are provided showing the gradual changes in DL,NO and DL,CO from rest to exercise at increasing intensitiesof up to 60% of maximal workload. The measurement of diffusing capacity and evaluation of alveolar-capillary reserve is a useful tool to evaluate the lung's ability to respond to exercise both in the healthy population as well as in patient populations such as those with chronic lung disease.

Lung function deficits and bronchodilator responsiveness at 12 years of age in children born very preterm compared with controls born at term.

Very preterm birth is associated with lung function impairment later in life, but several aspects have not been studied. We aimed to comprehensively assess lung function at school age in very preterm infants and term controls, with special emphasis on bronchopulmonary dysplasia (BPD), sex, and bronchodilator response. At 12 years of age, 136 children born very preterm (85 with and 51 without BPD) and 56 children born at term performed spirometry, body plethysmography, impulse oscillometry, measurement of diffusion capacity, and multiple breath washout, before and after bronchodilator inhalation. Airway symptoms and a diagnosis of asthma were more common in children born very preterm. These children had more airflow limitation, seen as lower forced expiratory volume in 1 s (FEV1 ) (p < .001), FEV1 /forced vital capacity (FVC) (p = .011), and mean forced expiratory flow between 25% and 75% of FVC (p < .001), and a higher total and peripheral airway resistance compared with term-born controls. There was no difference in total lung capacity but air trapping and lung clearance index were higher in children born very preterm. Diffusion capacity was lower in children born very preterm, especially in those with a diagnosis of BPD. In most other tests, the differences between preterm-born children with or without BPD were smaller than between children born preterm versus at term. Boys born preterm had more lung function deficits than preterm-born girls. In children born very preterm, airway obstruction was to a large extent reversible. At 12 years of age, children born very preterm had lower lung function than children born at term in most aspects and there was only little difference between children with or without BPD. Airway obstruction improved markedly after bronchodilator inhalation.

Functional diagnostics of the respiratory system in patients with Long COVID

Given the considerable number of people with persistent respiratory symptoms more than 4 weeks after COVID-19, it is important to determine which examinations are most informative for assessing respiratory function, prognosis, and monitoring the effectiveness of treatment in such patients. The purpose of this study is to cover the functional diagnosis of the respiratory system in patients who survived Long COVID. Bibliosemantic and analytical research methods were applied. According to the world guidelines for patients with persistent respiratory symptoms after COVID-19, all of them should undergo respiratory system examinations: chest X-rays, spirometry, blood saturation measurements, lung diffusion capacity for carbon monoxide, walk tests, and others. The study confirmed that people who have had COVID-19, even after 1-6 months, show a decrease in diffusing capacity of the lung for carbon monoxide, which has a direct correlation with total lung capacity, the severity of clinical manifestations, and the results of rapid tests. Changes in spirometric parameters are observed much less frequently, mainly in patients hospitalised with severe pneumonia, which subsequently leads to post-cystic pulmonary fibrosis. Gradual improvement in functional respiratory tests occurs 3 months, 6 months, and 12 months after acute infection. The most informative tests for assessing respiratory function include the measurement of carbon monoxide diffusion capacity, total lung capacity, and blood gas composition. In conditions of limited access to the aforementioned diagnostic tests, and as a screening tool, quick tests such as the 3-minute/6-minute walk test (3MWT/6MWT) or the 1-minute sit-to-stand test (1-MSTST) can be utilised based on the patient's capabilities

Assessment of small airway dysfunction by impulse oscillometry (IOS) in COPD and IPF patients.

Small airway dysfunction is a pathological component of chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF), and impulse oscillometry is an easy-to-administer, effort-independent non-invasive test reflecting small airway dysfunction. We aimed to compare the impulse oscillometry (IOS) measurements between COPD and IPF patients and investigate their correlation with severity of both diseases and other conventional parameters. This was a prospective, longitudinal study. We longitudinally evaluated the baseline demographic characteristics, COPD Assessment Test (CAT) and modified Medical Research Council (mMRC) dyspnea scale, Pulmonary Function Test (PFT), Carbon Monoxide Diffusing Capacity (DLCO), Hemogram and Impulse Oscillometry measurements of the patients diagnosed with COPD and IPF. The study included 60 IPF patients and 48 COPD patients. The CAT and mMRC scores were higher in COPD patients. The majority of COPD patients were classified into Category B (46%), while 68% of IPF patients had Stage 1 GAP. The mean FEF 25-75%, which is typically considered to reflect small airway disease, was 93% in IPF patients, while it was significantly lower in COPD patients (29%). Impulse oscillometry measurements were consistent with spirometry parameters. IOS resistance and reactance values were significantly higher in COPD patients than in IPF patients. IOS is advantageous in COPD and IPF patients who cannot exhale due to severe dyspnea, as it is easy to administer and reflects small airway resistance better. Diagnosis of small airway dysfunction may be beneficial in the management of patients with IPF and COPD.

Respiratory function in uncomplicated type 1 diabetes: Blunted during exercise even though normal at rest!

Type 1 diabetes is associated with a substantially increased risk of impaired lung function, which may impair aerobic fitness. We therefore aimed to examine the ventilatory response during maximal exercise and the pulmonary diffusion capacity function at rest in individuals with uncomplicated type 1 diabetes. In all, 17 adults with type 1 diabetes free from micro-macrovascular complications (glycated haemoglobin: 8.0 ± 1.3%), and 17 non-diabetic adults, carefully matched to the type 1 diabetes group according to gender, age, level of physical activity and body composition, participated in our study. Lung function was assessed by spirometry and measurements of the combined diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) at rest. Subjects performed a maximal exercise test during which the respiratory parameters were measured. At rest, DLCO (30.4 ± 6.1ml min-1 mmHg-1 vs. 31.4 ± 5.7ml min-1 mmHg-1 , respectively, p=0.2), its determinants Dm (membrane diffusion capacity) and Vc (pulmonary capillary volume) were comparable among type 1 diabetes and control groups, respectively. Nevertheless, spirometry parameters (forced vital capacity=4.9 ± 1.0L vs. 5.5 ± 1.0L, p < 0.05; forced expiratory volume 1=4.0 ± 0.7L vs. 4.3 ± 0.7L, p < 0.05) were lower in individuals with type 1 diabetes, although in the predicted normal range. During exercise, ventilatory response to exercise was different between the two groups: tidal volume was lower in type 1 diabetes vs. individuals without diabetes (p < 0.05). Type 1 diabetes showed a reduced VO2max (34.7 ± 6.8 vs. 37.9 ± 6.3, respectively, p=0.04) in comparison to healthy subjects. Individuals with uncomplicated type 1 diabetes display normal alveolar-capillary diffusion capacity and at rest, while their forced vital capacity, tidal volumes and VO2 are reduced during maximal exercise.

Залежність рівня ендотеліну-1 у осіб, що перенесли негоспітальну пневмонію на тлі коронавірусної хвороби (COVID-19), від особливостей перебігу гострого й постгострого періодів

Abstract. The impairment of endothelial function is one of the mechanisms contributing to the increased risk of cardiovascular and cerebrovascular events in patients who have experienced community-acquired pneumonia associated with COVID-19. The aim of the study was to establish the connection between the level of endothelin-1 in peripheral blood of individuals who have experienced community-acquired pneumonia associated with COVID-19, with clinical-anamnestic, demographic, laboratory, and functional indicators in both the acute and post-acute periods. Materials and methods. 39 patients (age — 57.0 (48.5; 64.0) years, male — 18 (46.2 %), female — 21 (53.8 %)) survived COVID-19-associated community-acquired pneumonia were investigated. They were investigated on the 45.0 (40.0; 60.0) day from the onset of COVID-19 and had the dyspnea at the moment of the investigation. The examination included analyzing complaints, medical history and documentation, physical examination, pulse oximetry (SpO2 ), a 6-minute walk test (6MWT), measurement of lung diffusion capacity (DLco), laboratory methods (C-reactive protein (CRP), D-dimer, platelet count, endothelin-1 measurements). Results. Since it was found that patients, on one hand, had varying degrees of respiratory failure, different laboratory parameters during the acute period of COVID-19, and varying severity of dyspnea in the post-acute period of the disease, and on the other hand, exhibited wide fluctuations in endothelin-1 levels, a cluster analysis was conducted. Two clusters of patients were identified. Cluster 1 comprised 15 individuals with higher body mass index, lower SpO2 levels at the time of examination, and poorer results in the 6MWT and DLco compared to Cluster 2, which included 24 individuals. The level of endothelin-1 in Cluster 1 was significantly higher than that in Cluster 2. Clusters 1 and 2 were comparable in terms of age and gender but differed in terms of treatment conditions (outpatient or inpatient), duration of hospitalization, minimum SpO2 levels, CRP, and D-dimer levels in the acute period, and severity of the acute phase of COVID-19. Conclusion. A high level of endothelin-1 in patients who have experienced severe or critical COVID-19, accompanied by elevated levels of CRP and D-dimer, overweight or obesity, significant dyspnea, low tolerance to physical exertion, and poor DLco in post-acute period of COVID-19, indicates the necessity of careful monitoring of these individuals to prevent the development of adverse events in post-acute period of COVID-19.

Indicaciones e interpretación de la espirometría y de la prueba de difusión

Spirometry and the measurement of carbon monoxide diffusion capacity are two basic tests in the diagnostic algorithm of most lung diseases given their widespread availability, simplicity, and low cost. They are also important in presurgical evaluations and the evaluation of disability, as well as in the fields of legal and occupational medicine. They are fundamental tests for establishing the prognosis of certain illnesses, such as interstitial lung diseases. They require trained nursing department staff to conduct them and they must be performed in lung function laboratories that meet a series of technical requirements. The current SARS-CoV-2 pandemic has made it necessary for scientific societies to create specific documents and protocols in order to safely conduct these tests.

Forced expiratory flows and diffusion capacity in infants born from mothers with pre-eclampsia.

Animal models suggest pre-eclampsia (Pre-E) affects alveolar development, but data from humans are lacking. Assess the impact of Pre-E on airway function, diffusion capacity, and respiratory morbidity in preterm and term infants born from mothers with Pre-E. Infants born from mothers with and without Pre-E were recruited for this study; term and preterm infants were included in both cohorts. Respiratory morbidity in the first 12 months of life was assessed through monthly phone surveys. Raised volume rapid thoracoabdominal compression and measurement of diffusion capacity of the lung to carbon monoxide (DLCO) were performed at 6 months corrected age. There were 146 infants in the Pre-E cohort and 143 in the control cohort. The Pre-E cohort was further divided into nonsevere (N = 41) and severe (N = 105) groups. There was no significant difference in DLCO and DLCO/alveolar volume amongthe three groups. Forced vital capacity was similar amongthe three groups, but the nonsevere Pre-E group had significantly higher forced expiratory flows than the other two groups. After adjusting for multiple covariates including prematurity, the severe Pre-E group had a lower risk for wheezing in the first year of life compared to the other two groups. Pre-E is not associated with reduced DLCO, lower forced expiratory flows, or increased wheezing in the first year of life. These results differ from animal models and highlight the complex relationships between Pre-E and lung function and respiratory morbidity in human infants.

Persistent dyspnea after COVID-19 is not related to cardiopulmonary impairment; a cross-sectional study of persistently dyspneic COVID-19, non-dyspneic COVID-19 and controls.

Background: Up to 53% of individuals who had mild COVID-19 experience symptoms for >3-month following infection (Long-CoV). Dyspnea is reported in 60% of Long-CoV cases and may be secondary to impaired exercise capacity (VO2peak) as a result of pulmonary, pulmonary vascular, or cardiac insult. This study examined whether cardiopulmonary mechanisms could explain exertional dyspnea in Long-CoV. Methods: A cross-sectional study of participants with Long-CoV (n = 28, age 40 ± 11 years, 214 ± 85 days post-infection) and age- sex- and body mass index-matched COVID-19 naïve controls (Con, n = 24, age 41 ± 12 years) and participants fully recovered from COVID-19 (ns-CoV, n = 14, age 37 ± 9 years, 198 ± 89 days post-infection) was conducted. Participants self-reported symptoms and baseline dyspnea (modified Medical Research Council, mMRC, dyspnea grade), then underwent a comprehensive pulmonary function test, cardiopulmonary exercise test, exercise pulmonary diffusing capacity measurement, and rest and exercise echocardiography. Results: VO2peak, pulmonary function and cardiac/pulmonary vascular parameters were not impaired in Long- or ns-CoV compared to normative values (VO2peak: 106 ± 25 and 107 ± 25%predicted, respectively) and cardiopulmonary responses to exercise were otherwise normal. When Long-CoV were stratified by clinical dyspnea severity (mMRC = 0 vs mMRC≥1), there were no between-group differences in VO2peak. During submaximal exercise, dyspnea and ventilation were increased in the mMRC≥1 group, despite normal operating lung volumes, arterial saturation, diffusing capacity and indicators of pulmonary vascular pressures. Interpretation: Persistent dyspnea after COVID-19 was not associated with overt cardiopulmonary impairment or exercise intolerance. Interventions focusing on dyspnea management may be appropriate for Long-CoV patients who report dyspnea without cardiopulmonary impairment.

Restrictions of VC and DLCO in relation to asbestos-related computed tomographic findings quantified by ICOERD-based parameters

BackgroundEven almost 30 years after the ban on the use of asbestos in Germany, the effects of asbestos are still highly relevant in everyday clinical practice in occupational medicine. The aim of this study was to further investigate the significance of essential parameters of both pulmonary function diagnostics and imaging techniques (low-dose HR-TCT) for the prevention and early detection of asbestos-related morphological and functional lung changes.MethodsData from spirometry, body plethysmography and diffusion capacity, as well as CT images of the thorax, were retrospectively studied from 72 patients examined between 2017 and 2019 at the Institute for Occupational and Maritime Medicine (ZfAM), Hamburg, Germany. The subjects were divided into four subgroups according to the presence of comorbidities (concomitant cardiac diseases, obstructive ventilatory disorder, pulmonary function pattern consistent with emphysema, and no other pulmonary or cardiac diseases). These subgroups were analysed in addition to the overall collective. The CT images were evaluated according to the International Classification of Occupational and Environmental Respiratory Diseases (ICOERD) with radiological expertise. In addition, some asbestos-related parameters were newly quantified, and corresponding scores were defined based on ICOERD. Statistical analysis included the use of correlations and fourfold tables with calculation of Spearman's rho (ρ), Cohen’s κ, and accuracy.ResultsVital capacity (VC) is slightly reduced in the total collective compared to the normal population (mean 92% of predicted value), while diffusion capacity for CO (DLCO) shows predominantly pathological values, mean 70% of the respective predicted value. The CO transfer coefficient (DLCO/VA), which refers to alveolar volume (VA), also shows slightly decreased values (mean 87% pred.). Seventy-nine percent of patients (n = 57) had signs of pulmonary fibrosis on CT scans, and pleural plaques appeared in 58 of 72 patients (81%). Of the newly quantified additional parameters, particularly frequently described findings are subpleural curvilinear lines (SC, n = 39) and parenchymal bands (PB, n = 29). VC correlates well with the expression of pleural plaques (ρ = − 0.273, P < 0.05), and DLCO measures show a better correlation with fibrosis score (ρ = − 0.315, P < 0.01). A third, newly developed score, which includes the extent of pleural plaques and additional subpleural parameters instead of fibrosis parameters, shows significant correlations for both VC and DLCO (ρ = − 0.283, − 0.274, resp.; both P < 0.05).DiscussionThe importance of spirometry (VC) and diffusion capacity measurement (DLCO) as essential diagnostic procedures for the early detection of asbestos-related changes ‒ also including patients with relevant concomitant cardiac or pulmonary diseases ‒ was confirmed. Significant and better correlations between lung function changes (VC and DLCO) and abnormal CT findings are seen when parenchymal bands (PB), subpleural curvilinear lines (SC), and rounded atelectasis (RA) are quantitatively included into the evaluation, in addition to assessing the extent of pleural plaques alone. Therefore, when assessing CT images according to ICOERD, these parameters should also be quantified.

Older age at Fontan completion is associated with reduced lung volumes and increased lung reactance

BackgroundFontan patients have abnormal lung function, in particular restrictive lung disease and low diffusing capacity of carbon monoxide (DLCO). We sought to further characterise these abnormalities with detailed pulmonary function testing and examine associations with clinical parameters. Methods132 Fontan patients across Australia and New Zealand underwent spirometry, with 126 subjects included in final analyses. Measurement of diffusion capacity (DLCO) including its components (alveolar volume (VA) and rate of uptake of CO (KCO)) and oscillometry (reactance (X5) and resistance (R5)) were assessed in a subset of Fontan patients (n = 44) and healthy controls (n = 12). Double diffusion (to assess diffusing capacity of nitric oxide (DLNO), capillary blood volume (Vc), alveolar capillary membrane function (DmCO)) was performed in Fontan patients (n = 18) and healthy controls (n = 12). ResultsFEV1 and FVC z-scores were low in Fontan subjects (mean − 1.67 ± 1.24 and − 1.61 ± 1.29, respectively) and correlated with exercise capacity. Compared to controls, z-scores for X5, DLCO, KCO, VA and DLNO were significantly lower in Fontan patients. R5, Vc and DmCO z-scores were preserved. X5 was associated with VA (r = 0.41,p = 0.009) and DmCO (r = 0.61,p = 0.008). Older age at Fontan completion was associated with lower z-scores for FEV1 (r = −0.46,p = 0.002), FVC (r = −0.47,p = 0.002), X5 (r = −0.32,p = 0.033) and VA (r = −0.36,p = 0.022). ConclusionFontan patients have a reduced DLCO which is largely driven by low VA. Lung stiffness (X5) is increased which is associated with VA and DmCO. These parameters negatively correlate with older age of Fontan completion suggesting that earlier Fontan completion may have a beneficial effect on lung function.

Evaluation of Functional Operability Prior to Lung Surgery

Cardiac and pulmonary physiologic assessment is necessary for risk stratification before any lung resection. It may uncover hidden health issues, which can be addressed first to make patients fit for surgery. It allows for the surgeon to estimate the patient's risk for major complications and at the same time for the patient to understand the procedural risks and give informed consent or even reject surgery. Recommended work-up for both to cardiac risk evaluation and preoperative pulmonary function test algorithms are based on guidelines formulated by the ERS/ESTS and ACCP 1 3 4.Basic pulmonary function tests consist of spirometry, blood gas analysis and measurement of diffusion capacity (DLCO); followed by cardiopulmonary exercise testing (CPET) which estimates or measures the patient's oxygen consumption, and split function tests such as perfusion scintigraphy. Clinical assessment of both the patient's overall status and pulmonary function allows for an adequate assessment of overall operative risk. Pulmonary function tests are affected by multiple variables and as such prone to error. It is advisable to always question the validity of every work-up and to repeat any test if necessary.

Comparison of pulmonary function test, diffusion capacity, blood gas analysis and CT scan in patients with and without persistent respiratory symptoms following COVID-19

BackgroundLong-lasting symptoms following SARS-CoV2-infection have been described in several studies. However, there is only limited knowledge about the ongoing pathophysiology and the association with pathological findings in medical examinations.MethodsIn this post hoc analysis of a prospective trial, 135 patients following COVID-19 were enrolled and grouped with respect to the presence or absence of respiratory ongoing symptoms following COVID-19. Pulmonary function test (PFT), diffusion capacity measurement (TLCO SB and TLCO/VA), blood gas analysis (BGA), laboratory tests and high-resolution computed tomography (HRCT) of patients with persistent respiratory symptoms were compared to those of asymptomatic patients.ResultsIn this analysis, 71% (96/135) of all patients (mean age 49 years; range 20–91 years) reported long-lasting symptoms after a median (IQR) of 85 days (60–116) following COVID-19 whereby 57.8% (78/135) complained about persistent pulmonary symptoms. Pathological findings in blood test, PFT, TLCO, BGA and/or HRCT were found in 71.8% and 64.1% of patients with and without long-lasting respiratory symptoms respectively. Patients with persistent respiratory symptoms were significantly younger and presented a significant lower FVC (%), TLC (L), and TLCO SB compared to asymptomatic patients (p < 0.05). The multiple logistic regression results in a significant effect of age (p = 0.004) and TLCO SB (p = 0.042).ConclusionFollowing COVID-19, a large proportion of patients experience ongoing symptoms, whereby the respiratory symptoms are the predominant complaints. Compared to asymptomatic patients, patients with ongoing symptoms were younger and presented a significant lower FVC, TLC and TLCO SB. The multiple logistic regression demonstrated only a significant association between the TLCO SB as the only PFT parameter and the perceived symptoms.

Dyspnea and Pulmonary Function Among Participants in the Multicenter AIDS Cohort Study Using Protease Inhibitors: A Cross-Sectional Study.

People living with HIV (PLWH) have a higher prevalence of respiratory symptoms than people without human immunodeficiency virus (HIV). Antiretroviral therapy has been associated with worsened airflow limitation. This cross-sectional study assessed respiratory health impairment among PLWH and its association with protease inhibitor use using data from Multicenter AIDS Cohort Study visits between April 1, 2017 and March 31, 2018. Participants completed the St. George's Respiratory Questionnaire (SGRQ), modified Medical Research Council (mMRC) dyspnea scale, spirometry, and diffusion capacity measurement. Visit data were compared among PI users, non-PI users, and men without HIV. Binary and ordinal logistic models were used to determine the associations between HIV status, PI use, and covariates with primary outcomes of dichotomized SGRQ and mMRC dyspnea scores. Of PI users, 57/177 (32.2%) self-reported pulmonary disease compared with 132/501 (26.4%) of non-PI users and 105/547 (19.2%) men without HIV. Of PI users, 77/177 (45.3%) had SGRQ scores ≥10, while 171/501 (34.7%) of non-PI users and 162/549 (29.9%) of people living without HIV had SGRQ scores ≥10 (p = .001). Adjusted models found an association between PI use and SGRQ score ≥10 [odds ratio (OR) 1.91 (95% confidence interval [CI] 1.29-2.82), ref: HIV negative and OR 1.50 (95% CI 1.01-2.22) ref: non-PI users]. A similar association was found with mMRC scores and PI use [OR 1.79 (95% CI 1.21-2.64), ref: HIV negative and OR 1.53 (95% CI 1.04-2.25), ref: non-PI users]. PI use is associated with worse respiratory health status, increased dyspnea, and an increased prevalence of self-reported pulmonary disease.

Correlation between Measurement of Lung Diffusion Capacity Using Single Breath Methods (DLCO-SB) and COPD Group in Persahabatan Hospital Jakarta

Background: This was a preliminary study to measure DLCO-SB on COPD patients in Persahabatan Hospital to understand the prevalence of DLCO reduction among COPD patients.Methods: This was a cross sectional study of COPD patients who attended COPD-Asthma clinic in Persahabatan Hospital Jakarta. Spirometry and DLCO-SB were performed consecutively during May–July 2015. Comorbidities were also recorded.Results: Spirometry and DLCO-SB measurements were conducted on 65 COPD subjects of which 10.8% subjects were in COPD Group A, 29.2% Group B, 32.3% Group C and 27.7% Group D. The mean age was 64.15; mean FEV1% was 46.05%, mean DLCO measured was 19.42 ml/min/mmHg and the mean DLCO% was 72.00%. The proportion of DLCO decline among COPD patients was 56.92%. There were significant correlations between COPD group, GOLD COPD grade, FEV1, BMI and comorbidities with the DLCO value results. There were no significant correlation between DLCO value with sex, age, smoking history, Brinkmann Index, obstructive-restrictive criteria, comorbidities and length of COPD period. Conclusion: The proportion of DLCO decline among COPD patients was 56.92%. There were significant correlations between COPD group, GOLD COPD grade, FEV1, BMI and previous TB history with the results of DLCO.

Impact of persistent D-dimer elevation following recovery from COVID-19.

BackgroundElevated D-dimer is known as predictor for severity of SARS-CoV2-infection. Increased D-dimer is associated with thromboembolic complications, but it is also a direct consequence of the acute lung injury seen in COVID-19 pneumonia.ObjectivesTo evaluate the rate of persistent elevated D-dimer and its association with thromboembolic complications and persistent ground glass opacities (GGO) after recovery from COVID-19.MethodsIn this post hoc analysis of a prospective multicenter trial, patients underwent blood sampling, measurement of diffusion capacity, blood gas analysis, and multidetector computed tomography (MDCT) scan following COVID-19. In case of increased D-dimer (>0,5 μg/ml), an additional contrast medium-enhanced CT was performed in absence of contraindications. Results were compared between patients with persistent D-dimer elevation and patients with normal D-dimer level.Results129 patients (median age 48.8 years; range 19–91 years) underwent D-Dimer assessment after a median (IQR) of 94 days (64–130) following COVID-19. D-dimer elevation was found in 15% (19/129) and was significantly more common in patients who had experienced a severe SARS-CoV2 infection that had required hospitalisation compared to patients with mild disease (p = 0.049). Contrast-medium CT (n = 15) revealed an acute pulmonary embolism in one patient and CTEPH in another patient. A significant lower mean pO2 (p = 0.015) and AaDO2 (p = 0.043) were observed in patients with persistent D-Dimer elevation, but the rate of GGO were similar in both patient groups (p = 0.33).ConclusionIn 15% of the patients recovered from COVID-19, persistent D-dimer elevation was observed after a median of 3 months following COVID-19. These patients had experienced a more severe COVID and still presented more frequently a lower mean pO2 and AaDO2.

X-ray dark-field chest imaging for detection and quantification of emphysema in patients with chronic obstructive pulmonary disease: a diagnostic accuracy study

SummaryBackgroundAlthough advanced medical imaging technologies give detailed diagnostic information, a low-dose, fast, and inexpensive option for early detection of respiratory diseases and follow-ups is still lacking. The novel method of x-ray dark-field chest imaging might fill this gap but has not yet been studied in living humans. Enabling the assessment of microstructural changes in lung parenchyma, this technique presents a more sensitive alternative to conventional chest x-rays, and yet requires only a fraction of the dose applied in CT. We studied the application of this technique to assess pulmonary emphysema in patients with chronic obstructive pulmonary disease (COPD).MethodsIn this diagnostic accuracy study, we designed and built a novel dark-field chest x-ray system (Technical University of Munich, Munich, Germany)—which is also capable of simultaneously acquiring a conventional thorax radiograph (7 s, 0·035 mSv effective dose). Patients who had undergone a medically indicated chest CT were recruited from the department of Radiology and Pneumology of our site (Klinikum rechts der Isar, Technical University of Munich, Munich, Germany). Patients with pulmonary pathologies, or conditions other than COPD, that might influence lung parenchyma were excluded. For patients with different disease stages of pulmonary emphysema, x-ray dark-field images and CT images were acquired and visually assessed by five readers. Pulmonary function tests (spirometry and body plethysmography) were performed for every patient and for a subgroup of patients the measurement of diffusion capacity was performed. Individual patient datasets were statistically evaluated using correlation testing, rank-based analysis of variance, and pair-wise post-hoc comparison.FindingsBetween October, 2018 and December, 2019 we enrolled 77 patients. Compared with CT-based parameters (quantitative emphysema ρ=–0·27, p=0·089 and visual emphysema ρ=–0·45, p=0·0028), the dark-field signal (ρ=0·62, p<0·0001) yields a stronger correlation with lung diffusion capacity in the evaluated cohort. Emphysema assessment based on dark-field chest x-ray features yields consistent conclusions with findings from visual CT image interpretation and shows improved diagnostic performance than conventional clinical tests characterising emphysema. Pair-wise comparison of corresponding test parameters between adjacent visual emphysema severity groups (CT-based, reference standard) showed higher effect sizes. The mean effect size over the group comparisons (absent–trace, trace–mild, mild–moderate, and moderate–confluent or advanced destructive visual emphysema grades) for the COPD assessment test score is 0·21, for forced expiratory volume in 1 s (FEV1)/functional vital capacity is 0·25, for FEV1% of predicted is 0·23, for residual volume % of predicted is 0·24, for CT emphysema index is 0·35, for dark-field signal homogeneity within lungs is 0·38, for dark-field signal texture within lungs is 0·38, and for dark-field-based emphysema severity is 0·42.InterpretationX-ray dark-field chest imaging allows the diagnosis of pulmonary emphysema in patients with COPD because this technique provides relevant information representing the structural condition of lung parenchyma. This technique might offer a low radiation dose alternative to CT in COPD and potentially other lung disorders.FundingEuropean Research Council, Deutsche Forschungsgemeinschaft, Royal Philips, and Karlsruhe Nano Micro Facility.

Lung function declines more rapidly in treated HIV-positive people than in HIV-negative people

As ever greater numbers of people living with HIV now have access to antiretroviral therapy and achieve sustained viral suppression,1 the focus of HIV care turns toward optimising long-term outcomes of age-associated non-communicable comorbidities that are common in people living with HIV, including obstructive pulmonary disease.2 Cohort and cross-sectional studies demonstrate higher prevalence of respiratory symptoms, diagnoses (eg, COPD or emphysema), abnormal lung imaging (eg, emphysema), and impairments on spirometry and diffusion capacity measurements in people living with HIV.

Ventilation Heterogeneity in Asthma and COPD: The Value of the Poorly Communicating Fraction as the Ratio of Total Lung Capacity to Alveolar Volume

Background: The ventilation heterogeneity (VH) is reliably assessed by the multiple-breath nitrogen washout (MBNW), which provides indices of conductive (S_cond) and acinar (S_acin) VH as well as the lung clearance index (LCI), an index of global VH. VH can be alternatively measured by the poorly communicating fraction (PCF), that is, the ratio of total lung capacity by body plethysmography to alveolar volume from the single-breath lung diffusing capacity measurement. Objectives: Our objective was to assess VH by PCF and MBNW in patients with asthma and with COPD and to compare PCF and MBNW parameters in both patient groups. Method: We studied 35 asthmatic patients and 45 patients with COPD. Each patient performed spirometry, body plethysmography, diffusing capacity, and MBNW test. Results: Compared to COPD patients, asthmatics showed a significantly lesser degree of airflow obstruction and lung hyperinflation. In asthmatic patients, both PCF and LCI and S_acin values were significantly lower than the corresponding ones of COPD patients. In addition, in both patient groups, PCF showed a positive correlation with LCI (p < 0.05) and S_acin (p < 0.05), but not with S_cond. Lastly, COPD patients with PCF >30% were highly likely to have a value ≥2 of the mMRC dyspnea scale. Conclusions: These results showed that PCF, a readily measure derived from routine pulmonary function testing, can provide a comprehensive measure of both global and acinar VH in asthma and in COPD patients and can be considered as a comparable tool to the well-established MBNW technique.