Utility of the 52-Gene Risk Score to Identify Patients with Idiopathic Pulmonary Fibrosis at Greater Risk of Mortality in the Era of Antifibrotic Therapy.

PURPOSE: We investigated whether a 52-gene signature was associated with transplant-free survival and other clinically meaningful outcomes in patients with idiopathic pulmonary fibrosis (IPF) in the IPF-PRO Registry, which enrolled patients who were and were not taking antifibrotic therapy. METHODS: The 52-gene risk signature was implemented to classify patients as being at "high risk" or "low risk" of disease progression and mortality. Transplant-free survival and other outcomes were compared between patients with a low-risk versus high-risk signature. RESULTS: The 52-gene signature classified 159 patients as at low risk and 86 as at high risk; in these groups, respectively, 56.6% and 51.2% used antifibrotic therapy at enrollment. Among those taking antifibrotic therapy, patients with a low-risk versus high-risk signature were at decreased risk of death, a composite of lung transplant or death, and a composite of decline in DLco % predicted > 15%, lung transplant, or death. Similar results were observed in the overall cohort. CONCLUSIONS: These data suggest that the 52-gene signature can be used in patients with IPF treated with antifibrotic therapy to distinguish patients at higher risk of disease progression and mortality.

Quantitative CT analysis of idiopathic pulmonary fibrosis and correlation with lung function study.

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% (R2 = 0.301, 0.301, 0.300, and 0.302, respectively, all P-values < 0.001), and GGO% was the best predictor of DLCO% (R2 = 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.

Clinical implications of six-minute walk test in patients with idiopathic pulmonary fibrosis: a retrospective cohort study.

BACKGROUND: A six-minute walk test (6MWT) is a reproducible, easily performed test, and is widely used to determine functional exercise capacity in patients with idiopathic pulmonary fibrosis (IPF). However, there is currently a paucity of data on the clinical significance of baseline and serial 6-minute walk tests in patients with IPF, especially in Asian patients. OBJECTIVES: We aimed to investigate the clinical significance of serial 6MWT in patients with IPF, especially in Asian patients. DESIGN: This is a single-center retrospective cohort study. METHODS: Clinical data of patients diagnosed with IPF at a tertiary center in Korea were retrospectively analyzed. IPF diagnosis was defined according to the clinical guidelines of the American Thoracic Society (ATS)/European Respiratory Society (ERS)/Japanese Respiratory Society/Latin American Thoracic Association. RESULTS: There were 216 patients diagnosed with IPF from December 2012 to January 2022, of whom 198 had a baseline of 6MWT data. The mean age of the cohort was 66.9 ± 8.6, and 89% were male. The non-survivors showed significantly lower six-minute walk distance (6MWD), minimum saturation of peripheral oxygen (SpO2) during 6MWT, forced vital capacity, and diffusing capacity of the lung for carbon monoxide than survivors at baseline. A multivariate Cox analysis demonstrated that lower minimum SpO2 was independently associated with increased mortality rates (Hazard ratio (HR): 1.081, 95% confidence interval (CI): 1.024-1.142, p = 0.005). Higher mortality rates were also associated with echocardiographic-determined pulmonary hypertension (HR: 2.466, 95% CI: 1.149-5.296, p = 0.021) at diagnosis. Among 144 patients with 6MWT results at 12 months, patients with a decline of 50 m or more in the 6MWD showed poorer overall survival than others (median survival: 45.0 months vs 58.0 months, p < 0.001). CONCLUSIONS: Baseline lower minimum SpO2 during 6MWT was an independent prognostic factor in patients with IPF, and a decline in 6MWD in serial follow-up was also associated with a poorer prognosis. These findings suggest that both baseline 6MWT and follow-up data are important in the prognostication of patients with IPF.

Differential effects of balloon pulmonary angioplasty on chronic thromboembolic pulmonary disease.

BACKGROUND: Decreased diffusing capacity of the lungs for carbon monoxide (DLco) is associated with microvascular damage in chronic thromboembolic pulmonary hypertension (CTEPH). Balloon pulmonary angioplasty (BPA) is an effective treatment for CTEPH, but the efficacy of BPA in patients with CTEPH with low DLco remains unclear because BPA does not directly address microvascular damage. This study investigates the influence of microvasculopathy on BPA in CTEPH according to DLco. METHODS: We retrospectively analysed data from patients with inoperable CTEPH who underwent BPA at the University of Tokyo Hospital from July 2011 to August 2023. The patients were classified into two groups based on their preprocedural DLco (normal DLco (ND) and low DLco (LD) groups), with a DLco cut-off value of 80%. We compared the patient characteristics and effectiveness of BPA between the groups. RESULTS: Among the 75 patients, 36 were in the LD group. The LD group had a shorter 6-minute walking distance (324±91 vs 427±114 m) than the ND group but the mean pulmonary artery pressure (mPAP) was similar (38.9±7.3 vs 41.1±9.2 mm Hg) before BPA. BPA improved the haemodynamic status and exercise tolerance in both groups. The LD group exhibited a higher mPAP (25.1±7.4 vs 21.5±5.6 mm Hg) and required more sessions of BPA (median 6 vs 4). Based on the analysis of covariance adjusted for baseline values, low DLco significantly correlated with mPAP (sß=-0.304, 95% CI -7.015 to -1.132, p=0.007) and pulmonary vascular resistance (sß=-0.324, 95% CI -141.0 to -29.81, p=0.003). CONCLUSIONS: BPA was associated with an improvement in the haemodynamic status and exercise tolerance in patients with CTEPH even with low DLco. However, low DLco may attenuate the effect of BPA on mPAP and pulmonary vascular resistance and require more treatment sessions.

Pulmonary function trajectories in COVID-19 survivors with and without pre-existing respiratory disease.

A significant proportion of COVID-19 survivors still experience a reduced diffusion capacity three and twelve months after discharge. We aimed to compare pulmonary function trajectories between hospitalized COVID-19 patients with pre-existing respiratory disease (PRD) and patients without pre-existing respiratory disease (Non-PRD) at three and twelve months after hospital discharge. This single-centre retrospective cohort study included COVID-19 patients admitted to the VieCuri Medical Centre (Venlo, the Netherlands) between February and December 2020 that were invited to the outpatient clinic at three and twelve months after discharge. During this visit, pulmonary function tests were performed and impairments were based on lower limit of normal. Data of 239 patients were analysed (65% male, 66 ± 10 years, and 26% with a history of respiratory disease). Three months after discharge, 49% and 64% of the Non-PRD patients (n = 177) and PRD patients (n = 62) had a low diffusion capacity, respectively. This improved over time in Non-PRD patients (p = 0.003), but not in PRD patients (p = 0.250). A low diffusion capacity was still observed in 34% and 57% of the Non-PRD and PRD group, respectively, twelve months after discharge. Pulmonary function impairments, mainly a reduced diffusion capacity, are observed among hospitalized COVID-19 patients with PRD and Non-PRD, at three and twelve months follow-up. Although diffusion capacity impairments restore over time in Non-PRD patients, poor recovery was observed among PRD patients.

Using the phase III slope of exhaled methane during a single breath DLCO test to assess ventilation heterogeneity.

BACKGROUND: The Phase III slope from a single breath nitrogen washout test provides information about ventilation heterogeneity (VH) in the lungs. PURPOSE: To determine if the Phase III slope from the exhaled tracer gas concentration during a standard, single breath DLCO test using rapid gas analysis provides similar information about VH. BASIC PROCEDURES: Retrospective analysis of clinical pulmonary function laboratory data including spirometry, lung volumes, and DLCO. The normalized Phase III slope from the exhaled CH4 concentration (SnCH4) was compared among different patterns of physiologic abnormality and with VA/TLC as an indicator of VH. MAIN FINDINGS: SnCH4 was the steepest in the group with "Obstruction and Low DLCO", with significant differences between this group and the "Normal", "Obstruction with Normal DLCO", "Mixed Obstruction and Restriction" and "Isolated Low DLCO" groups. SnCH4 was steeper in current and former smokers compared to non-smokers. Among the entire study sample, SnCH4 correlated with VA/TLC (Spearman rho = -0.56, p < 0.01) and remained a significant determinant of VA/TLC by regression modeling. PRINCIPAL CONCLUSIONS: The SnCH4 derived from a standard, single breath DLCO test using rapid gas analysis varied among distinct patterns of physiologic abnormalities and was associated with VA/TLC as a measure of VH.

Comprehensive appraisal of lung function in young COPD patients: a single center observational study.

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 FEV1) (1.4 vs.1.2 L, P = 0.019), diffusing capacity of the lung for carbon monoxide (DLCO) (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 DLCO 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 DLCO. These results underscore the importance of a comprehensive assessment of lung function in young COPD patients.

Measuring lung diffusing capacity: an opportunity for improved medical surveillance and disability evaluation of coal miners.

OBJECTIVES: Spirometry is the primary lung function test utilised for medical surveillance and disability examination for coal mine dust lung disease. However, spirometry likely underestimates physiologic impairment. We sought to characterise abnormalities of single-breath diffusing capacity for carbon monoxide (DLCO) among a population of former coal miners. METHODS: Data from 3115 former coal miners evaluated at a West Virginia black lung clinic between 2006 and 2015 were retrospectively analysed to study the association between diffusion impairment (abnormally low DLCO), resting spirometry and the presence and severity of coal workers' pneumoconiosis on chest radiography. We developed ordinary least squares linear regression models to evaluate factors associated with per cent predicted DLCO (DLCOpp). RESULTS: Diffusion impairment was identified in 20.2% of subjects. Ten per cent of all miners with normal spirometry had diffusion impairment including 7.4% of never smokers. The prevalence of diffusion impairment increased with worsening radiographic category of pneumoconiosis. Mean DLCOpp decreased with increasing small opacity profusion subcategory in miners without progressive massive fibrosis. Linear regression analysis also showed significant decreases in DLCOpp with increasing small opacity profusion and presence of large opacities. CONCLUSIONS: Diffusion impairment is common among former coal miners, including among never smokers, miners without radiographic pneumoconiosis and miners with normal spirometry. These findings demonstrate the value of including DLCO testing in disability examinations of former coal miners and an important role for its use in medical surveillance of working miners to detect early chronic lung disease.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

The Impact of Different Smoking Behavior on Pulmonary Function and Pulmonary Hypertension Among Chinese Male Patients with Chronic Obstructive Pulmonary Disease.

Purpose: Cigarette smoking is the most recognized risk factor of chronic obstructive pulmonary disease (COPD) in China. However, there are no studies analyzing the impact of different smoking behaviors on pulmonary function and pulmonary hypertension (PH) among Chinese male patients with COPD. Patients and Methods: Chinese male smokers with COPD performed pulmonary function tests. Clinical characteristics, smoking behavior features, spirometry and echocardiographic results were compared between the two groups stratified by initial smoking age (18 years old) or complicated PH. Results: The early-smoking group had more respiratory symptoms, more severe smoking behavior, worse pulmonary function with lower FEV1%pre (38.5% vs 70.2%) and FEV1/FVC% (47.5% vs 63.8%), and higher systolic pulmonary artery pressure (sPAP: 38.6 vs 33.9 mmHg) than the late-smoking group. Initiating smoking before adulthood was an independently contributing factor of ventilatory dysfunction and Global Initiative for Obstructive Lung Disease (GOLD) stage escalation. It also had a significant interaction with long smoking duration (≥30 years), characterized by markedly decreased lung volumes (VC%pre: 64.0% vs 84.5%), impaired diffusing capacity (DLCO%pre: 58.0% vs 76.8%) and severe emphysema (RV/TLC%pre: 145.2% vs 130.2%). COPD patients complicated with PH exhibited worse ventilatory function (FEV1%pre: 43.2% vs 56.2%), impaired diffusion capacity (DLCO%pre: 56.7% vs 77.1%) and decreased lung volume (VC%pre: 67.67% vs 75.38%). Both severe smoking behaviors and impaired pulmonary function had close correlations with sPAP. Conclusion: The early-smoking group exhibited predominantly ventilation dysfunction and had complex interactions with long smoking duration to further affect lung volume and diffusion capacity. Different smoking behaviors influenced variations of pulmonary dysfunction and comorbid PH in patients with COPD.

Impact on pulmonary, cardiac, and renal function and long-term quality of life after hospitalization for acute respiratory distress syndrome due to COVID-19: Protocol of the Post-COVID Brazil 3 study.

RATIONALE: Evidence about long-term sequelae after hospitalization for acute respiratory distress syndrome due to COVID-19 is still scarce. PURPOSE: To evaluate changes in pulmonary, cardiac, and renal function and in quality of life after hospitalization for acute respiratory distress syndrome secondary to COVID-19. METHODS: This will be a multicenter case-control study of 220 participants. Eligible are patients who are hospitalized for acute respiratory distress syndrome due to COVID-19. In the control group, individuals with no history of hospitalization in the last 12 months or long-term symptoms of COVID-19 will be selected. All individuals will be subjected to pulmonary spirometry with a carbon monoxide diffusion test, chest tomography, cardiac and renal magnetic resonance imaging with gadolinium, ergospirometry, serum and urinary creatinine, total protein, and urinary microalbuminuria, in addition to quality-of-life questionnaires. Patients will be evaluated 12 months after hospital discharge, and controls will be evaluated within 90 days of inclusion in the study. For all the statistical analyses, p < 0.05 is the threshold for significance. RESULTS: The primary outcome of the study will be the pulmonary diffusing capacity for carbon monoxide measured after 12 months. The other parameters of pulmonary, cardiac, and renal function and quality of life are secondary outcomes. CONCLUSION: This study aims to determine the long-term sequelae of pulmonary, cardiac, and renal function and the quality of life of patients hospitalized for acute respiratory distress syndrome due to COVID-19 in the Brazilian population.

Prognostic value of pulmonary diffusing capacity for carbon monoxide and ventilation-perfusion SPECT findings in pulmonary arterial hypertension.

Reduced pulmonary diffusing capacity for carbon monoxide (DLCO) can be observed in pulmonary arterial hypertension (PAH) and associates with increased mortality. However, the prognostic value of DLCO when corrected for haemoglobin (DLCOc), an independent modifier of DLCO, remains understudied. Additionally, the prognostic role of ventilation (V)-perfusion (Q) emission computed tomography (V/Q SPECT) findings in patients with PAH, which may concurrently be performed to rule out chronic thromboembolic pulmonary hypertension, is uncertain. A retrospective cohort study was conducted on 152 patients with PAH referred to a tertiary hospital for evaluation from January 2011 to January 2020. Lung function tests, clinical data and V/Q SPECT were ascertained. Cox regression analysis was performed to evaluate the association between DLCOc, DLCO and V/Q SPECT defects at referral with all-cause mortality. In equally adjusted Cox regression analysis, each percentage increase in DLCOc % predicted (%pred) (hazard ratio (HR) 0.97; 95% CI: 0.94-0.99) and DLCO%pred (HR 0.97; 95% CI: 0.94-0.99) was similarly associated with all-cause mortality. There was no detectable difference in area under the curve for prediction of all-cause mortality by DLCOc%pred and DLCO%pred (C-index 0.71 and 0.72, respectively, P = 0.85 for difference). None of the defects noted on V/Q SPECT were significantly associated with mortality, but mismatched defects were associated with lower values of DLCOc%pred and DLCO%pred. DLCOc%pred and DLCO%pred perform equally as prognostic markers in PAH, supporting the use of either metric when available for prognostic stratification.

Interferon-signaling pathways are upregulated in people with HIV with abnormal pulmonary diffusing capacity (DL CO ).

OBJECTIVE: People with HIV (PWH) are at greater risk of developing lung diseases even when they are antiretroviral therapy (ART)-adherent and virally suppressed. The most common pulmonary function abnormality in PWH is that of impaired diffusing capacity of the lungs for carbon monoxide (DL CO ), which is an independent risk factor for increased mortality in PWH. Earlier work has identified several plasma biomarkers of inflammation and immune activation to be associated with decreased DL CO . However, the underpinning molecular mechanisms of HIV-associated impaired DL CO are largely unknown. DESIGN: Cross-sectional pilot study with PWH with normal DL CO (values greater than or equal to the lower limit of normal, DL CO  ≥ LLN, N = 9) or abnormal DL CO (DL CO  < LLN, N = 9). METHODS: We compared the gene expression levels of over 900 inflammation and immune exhaustion genes in PBMCs from PWH with normal vs. abnormal DL CO using the NanoString technology. RESULTS: We found that 26 genes were differentially expressed in the impaired DL CO group. These genes belong to 4 categories: 1. Nine genes in inflammation and immune activation pathways, 2. seven upregulated genes that are direct targets of the interferon signaling pathway, 3. seven B-cell specific genes that are downregulated, and 4. three miscellaneous genes. These results were corroborated using the bioinformatics tools DAVID (Database for Annotation, Visualization and Integrated Discovery) and GSEA (Gene Sets Enrichment Analysis). CONCLUSION: The data provides preliminary evidence for the involvement of sustained interferon signaling as a molecular mechanism for impaired DL CO in PWH.

Preoperative DLCO predicts severe early complications after liver transplantation.

BACKGROUND: Severe early complications are common after liver transplantation (LT) and are a key determinant of LT-related morbidity and mortality. The aim of this study was to assess whether lung function measured in the pre-operative period predicted complicated outcomes in the first month after LT. MATERIAL AND METHODS: Patients with mild-to-moderate liver disease (Model for End stage Liver Disease-MELD score≤30) who underwent LT between October 2015 and May 2020 in a single centre were retrospectively included. The primary endpoint was the occurrence of severe early complications after LT defined by mechanical ventilation duration > 2 days or length of ICU stay > 7 days or reintubation or death < 1 month after LT. RESULTS: One hundred and twenty patients were included (age 59 [53-64] years, 72 % men). Forty patients (33 %) had early complications after LT. Measured and%predicted hemoglobin-corrected lung transfer capacity for carbon monoxide (DLCOc) were significantly lower in patients with severe early complications after LT. DLCOc was the only variable that associated independently with severe early complications by multivariate analysis. DLCOc under 16.3 ml.min-1.mmHg-1 predicted respiratory complications with a sensitivity of 67.5 % and a specificity of 62.9 %. DLCOc%pred under 61.5 % had a sensitivity of 56.8 % and a specificity of 72 %. DLCOc independently associated with forced vital capacity (FVC), pulmonary emphysema, and the muscle mass index. CONCLUSION: A decrease in DLCOc indicated an increased risk of severe early complications after LT.

Effect of Ultramarathon Trail Running at Sea Level and Altitude on Alveolar-Capillary Function and Lung Diffusion.

INTRODUCTION: Endurance exercise at altitude can increase cardiac output and pulmonary vascular pressure to levels that may exceed the stress tolerability of the alveolar-capillary unit. This study examined the effect of ultramarathon trail racing at different altitudes (ranging from <1000 m to between 1500 and 2700 m) on alveolar-capillary recruitment and lung diffusion. METHODS: Cardiac and lung function were examined before and after an ultramarathon in 67 runners (age: 41 ± 9 yr, body mass index: 23 ± 2 kg·m -2 , 10 females), and following 12-24 h of recovery in a subset ( n = 27). Cardiac biomarkers (cTnI and BNP) were assessed from whole blood, whereas lung fluid accumulation (comet tails), stroke volume (SV), and cardiac output ( Q ) were quantified via echocardiography. Lung diffusing capacity for carbon monoxide (DLco) and its components, alveolar membrane conductance (Dm) and capillary blood volume (Vc), were determined via a single-breath method at rest and during three stages of submaximal semirecumbent cycling (20, 30, and 40 W). RESULTS: Average race time was 25 ± 12 h. From pre- to post-race, there was an increase in cardiac biomarkers (cTnI: 0.04 ± 0.02 vs 0.13 ± 0.03 ng·mL -1 , BNP: 20 ± 2 vs 112 ± 21 pg·mL -1 ; P < 0.01) and lung comet tails (2 ± 1 vs 7 ± 6, P < 0.01), a decrease in resting and exercise SV (76 ± 2 vs 69 ± 2 mL, 40 W: 93 ± 2 vs 88 ± 2 mL; P < 0.01), and an elevation in Q at rest (4.1 ± 0.1 vs 4.6 ± 0.2 L·min -1 , P < 0.01; 40 W: 7.3 ± 0.2 vs 7.4 ± 0.3 L·min -1 , P = 0.899). Resting DLco and Vc decreased after the race ( P < 0.01), whereas Dm was unchanged ( P = 0.465); however, during the three stages of exercise, DLco, Vc, and Dm were all reduced from pre- to post-race (40 W: 36.3 ± 0.9 vs 33.0 ± 0.8 mL·min -1 ·mm Hg -1 , 83 ± 3 vs 73 ± 2 mL, 186 ± 6 vs 170 ± 7 mL·min -1 ·mm Hg -1 , respectively; P < 0.01). When corrected for alveolar volume and Q , DLco decreased from pre- to post-race ( P < 0.01), and changes in DLco were similar for all ultramarathon events ( P > 0.05). CONCLUSIONS: Competing in an ultramarathon leads to a transient increase in cardiac injury biomarkers, mild lung-fluid accumulation, and impairments in lung diffusion. Reductions in DLco are predominantly caused by a reduced Vc and possible pulmonary capillary de-recruitment at rest. However, impairments in alveolar-capillary recruitment and Dm both contribute to a fall in exertional DLco following an ultramarathon. Perturbations in lung diffusion were evident across a range of event distances and varying environmental exposures.

Pulmonary diffusing capacity for carbon monoxide and nitric oxide after COVID-19: A prospective cohort study (the SECURe study).

Many patients exhibit persistently reduced pulmonary diffusing capacity after coronavirus disease 2019 (COVID-19). In this study, dual test gas diffusing capacity for carbon monoxide and nitric oxide (DL,CO,NO) metrics and their relationship to disease severity and physical performance were examined in patients who previously had COVID-19. An initial cohort of 148 patients diagnosed with COVID-19 of all severities between March 2020 and March 2021 had a DL,CO,NO measurement performed using the single-breath method at 5.7 months follow-up. All patients with at least one abnormal DL,CO,NO metric (n = 87) were revaluated at 12.5 months follow-up. The DL,CO,NO was used to provide the pulmonary diffusing capacity for nitric oxide (DL,NO), the pulmonary diffusing capacity for carbon monoxide (DL,CO,5s), the alveolar-capillary membrane diffusing capacity and the pulmonary capillary blood volume. At both 5.7 and 12.5 months, physical performance was assessed using a 30 s sit-to-stand test and the 6 min walk test. Approximately 60% of patients exhibited a severity-dependent decline in at least one DL,CO,NO metric at 5.7 months follow-up. At 12.5 months, both DL,NO and DL,CO,5s had returned towards normal but still remained abnormal in two-thirds of the patients. Concurrently, improvements in physical performance were observed, but with no apparent relationship to any DL,CO,NO metric. The severity-dependent decline in DL,NO and DL,CO observed at 5.7 months after COVID-19 appears to be reduced consistently at 12.5 months follow-up in the majority of patients, despite marked improvements in physical performance.

Influence of Impaired Diffusing Capacity and Sleep-disordered Breathing on Nocturnal Hypoxemia and Health Outcomes in Men with and without Human Immunodeficiency Virus.

Rationale: Nocturnal hypoxemia is common in sleep-disordered breathing (SDB) and is associated with increased morbidity and mortality. Although impaired diffusing capacity of the lung for carbon monoxide (DlCO) is associated with daytime hypoxemia, its influence on SDB-related nocturnal hypoxemia is not known. Objectives: To characterize the effects of DlCO impairment on SDB-related nocturnal hypoxemia and associated health outcomes. Methods: Data from a multicenter cohort of men with and without human immunodeficiency virus (HIV) infection, with concomitant measures of DlCO and home-based polysomnography (n = 544), were analyzed. Multivariable quantile regression models characterized associations between DlCO and several measures of SDB-related hypoxemia (e.g., total sleep time with oxygen saturation as measured by pulse oximetry [SpO2] < 90% [T90]). Structural equation models were used to assess associations of impaired DlCO and SDB-related hypoxemia measures with prevalent hypertension and type 2 diabetes. Results: DlCO impairment (<80% predicted) was associated with sleep-related hypoxemia. Participants with severe SDB (apnea-hypopnea index ⩾ 30 events/h) and impaired DlCO had higher T90 (median difference, 15.0% [95% confidence interval (CI), 10.3% to 19.7%]) and average SDB-related desaturation (median difference, 1.0 [95% CI, 0.5 to 1.5]) and lower nadir SpO2 (median difference, -8.2% [95% CI, -11.4% to -4.9%]) and average SpO2 during sleep (median difference, -1.1% [95% CI, -2.1% to -0.01%]) than those with severe SDB and preserved DlCO. Higher T90 was associated with higher adjusted odds of prevalent hypertension (odds ratio, 1.39 [95% CI, 1.14 to 1.70]) and type 2 diabetes (odds ratio, 1.25 [95% CI, 1.07 to 1.46]). Conclusions: DlCO impairment in severe SDB was associated with sleep-related hypoxemia, prevalent hypertension, and type 2 diabetes. Assessment of SDB should be considered in those with impaired DlCO to guide testing and risk stratification strategies.