The Prognostic Value of Residual Volume/Total Lung Capacity in Patients with Chronic Obstructive Pulmonary Disease

Residual Volume and Total Lung Capacity at Diagnosis Predict Overall Survival in Non-Small Cell Lung Cancer Patients

BACKGROUND

Residual volume (RV) / total lung capacity (TLC) ratio has been found to better predict functional impairments than spirometry and is associated with mortality in chronic obstructive pulmonary disease; however, it is rarely studied in lung cancer. Our previous work established spirometry as a prognostic factor for lung cancer, and we aimed to further investigate the prognostic value of TLC and RV in lung cancer patients.

METHODS

We identified newly diagnosed non-small cell lung cancer (NSCLC) patients who underwent static lung function tests prior to any cancer therapy between 1992 and 2020 in a longitudinal cohort of lung cancer patients: the Boston Lung Cancer Study. Cox proportional-hazards model was used to estimate the association between each lung volume test with overall survival.

RESULTS

Among 2348 NSCLC patients, 57.2% were diagnosed at stage I and 63.8% underwent surgery, with 1352 deaths observed over a median survival of 66.9 months. Higher RV, RV%, and lower TLC, TLC% were associated with worse overall survival marginally; RV/TLC was associated with overall survival as a quantitative trait, with one standard deviation (11.24%) increase in RV/TLC associated with 19.2% higher risk of mortality (HR = 1.192 [95% CI: 1.114, 1.277]) after covariate adjustment. Statistically significant interactions were found between RV/TLC and spirometry, and higher mortality risks were found with higher RV/TLC in patients across spirometry status and cancer stages.

CONCLUSION

NSCLC patients with higher RV/TLC ratios at diagnosis had worse overall survival, even when spirometry was within the predicted range. These findings suggest that lung volume measurements provide prognostic information beyond standard spirometry, supporting the need for further mechanistic and interventional studies to determine their clinical utility.

Comparison of GLI-2021 standards with ECSC standards for static lung volume interpretation in patients with respiratory diseases

BACKGROUND

In 2021, the Global Lung Function Initiative (GLI) has published new reference equations for static lung volumes (GLI-2021). Many learned societies recommend the use of GLI reference values for interpreting pulmonary function tests (PFT), while pointing out the need for clinicians to be aware of the consequences for their routine practice. We aimed to compare the GLI-2021 reference values and the 1993 European Coal and Steel Community (ECSC) standards on the interpretation of static lung volume data in patients with a probable static hyperinflation or a probable restrictive ventilatory disorder.

METHODS

We analyzed plethysmographic PFT data from 2 groups of patients: a group of patients with symptoms compatible with chronic bronchitis (CB) and a group of patients with symptoms compatible with interstitial lung disease (ILD). We investigated discrepancies in the evaluations of static lung volumes when using the ECSC vs. the GLI-2021 reference values.

RESULTS

2897 sets of PFT results (including 1598 in men) were included. In the CB group, the proportion of hyperinflation was higher for both sexes with the GLI-2021 standards. In the ILD group, the proportion of restrictive ventilatory disorders was higher in women but lower in men with the GLI-2021 standards.

CONCLUSION

A move from use of the ECSC standards for static lung volumes to the GLI-2021 standards might lead to a higher estimated proportion of hyperinflation (particularly in participants with CB), together with changes in the proportion of restrictive ventilatory disorders (a lower value in men and a higher value in women with ILD).

Air trapping in patients with idiopathic pulmonary fibrosis: a retrospective case-control study

Idiopathic pulmonary fibrosis (IPF) is characterised by progressive worsening of lung function. In some cases, IPF is accompanied by air-trapping and emphysema. This study aimed to evaluate air trapping quantified with RV/TLC in patients with IPF. This retrospective study included 122 patients diagnosed with IPF in South Korea between January 2011 and December 2020. Air trapping was defined as RV/TLC ≥ 0.40. Increased RV/TLC was found in 34.4% of all patients. The RV/TLC negatively correlated with lung function (forced expiratory volume in 1 s and functional vital capacity [FVC]) and showed consistent results after 1 year of follow-up. After propensity score matching, FVC and diffusion capacity between the groups showed no statistical difference. No difference in lung function decline was found between the increased and not increased RV/TLC groups. Regarding univariable analysis, the patients in the increased RV/TLC group had a lower risk of all-cause mortality (hazard ratio 1.753, P = 0.034). Using multivariable analysis, age, pirfenidone treatment, and FVC were significant factors for survival but not increased RV/TLC. Increased RV/TLC was related to emphysema and demonstrated a negative relationship with lung function. Although increased RV/TLC might relate to poor clinical outcome, it was not independent prognostic factor for IPF.

Utility of exhaled nitric oxide to guide mild asthma treatment in atopic patients and its correlation with asthma control test score: a randomized controlled trial

BACKGROUND

Fractional exhaled nitric oxide (FeNO) is used for the diagnosis and monitoring of asthma, although its utility to guide treatment and its correlation with other tools is still under discussion. We study the possibility to withdraw inhaled corticosteroid treatment in atopic patients with mild asthma based on the FeNO level, as well as to study its correlation with other clinical control tools.

METHODS

Prospective and randomized study including atopic patients aged 18 to 65 with mild asthma, stable, on low-dose inhaled corticosteroid (ICS) treatment, who had their treatment withdrawn based on a FeNO level of 40 ppb. Patients were randomized into two groups: control group (treatment with ICS was withdrawn regardless of FeNO level) and experimental group (according to the FeNO levels, patients were assigned to one of two groups: FeNO > 40 ppb on treatment with budesonide 200 mcg every 12 h and SABA on demand; FeNO ≤ 40 ppb only with SABA on demand). Follow-up was conducted for one year, during which medical assessment was performed with FeNO measurements, asthma control test (ACT), lung function tests (FEV1, FEV1/FVC, PEF, and RV/TLC), and recording of the number of exacerbations.

RESULTS

Ninety-two patients were included, with a mean age of 39.92 years (SD 13.99); 46 patients were assigned to the control group, and 46 patients to the experimental group. The number of exacerbations was similar between the groups (p = 0.301), while the time to the first exacerbation was significantly shorter in the control group (30.86 vs. 99.00 days), p < 0.001, 95% CI (43.332-92.954). Lung function tests (FEV1, FEV1/FVC, PEF, and RV/TLC) showed no differences between the groups (p > 0.05). Both FeNO and ACT showed significant changes in the groups in which ICS was withdrawn (p < 0.05 for both parameters). A significant negative correlation was observed between FeNO and ACT (r = -0.139, p = 0.008).

CONCLUSIONS

In atopic patients with mild asthma, withdrawal of ICS based on an FeNO of 40 ppb led to worsened symptoms but without changes in lung function tests or an increase in exacerbations. There was a negative correlation between FeNO values and symptomatic control measured by the ACT.

TRIAL REGISTRATION

Clinical Trial Number: 2012-000372-42. Start Date: 2012-07-23. Trial registered prospectively ( https://www.clinicaltrialsregister.eu/ctr-search/search?query=2012-000372-42 ). This study adheres to CONSORT guidelines of randomised control trials.

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.

Lung Hyperinflation as Treatable Trait in Chronic Obstructive Pulmonary Disease: A Narrative Review

Lung hyperinflation (LH) is a common clinical feature in patients with chronic obstructive pulmonary disease (COPD). It results from a combination of reduced elastic lung recoil as a consequence of irreversible destruction of lung parenchyma and expiratory airflow limitation. LH is an important determinant of morbidity and mortality in COPD, partially independent of the degree of airflow limitation. Therefore, reducing LH has become a major target in the treatment of COPD over the last decades. Advances were made in the diagnostics of LH and several effective interventions became available. Moreover, there is increasing evidence suggesting that LH is not only an isolated feature in COPD but rather part of a distinct clinical phenotype that may require a more integrated management. This narrative review focuses on the pathophysiology and adverse consequences of LH, the assessment of LH with lung function measurements and imaging techniques and highlights LH as a treatable trait in COPD. Finally, several suggestions regarding future studies in this field are made.

Ventilation Management in a Patient with Ventilation-Perfusion Mismatch in the Early Phase of Lung Injury and during the Recovery

Chest trauma is one of the most serious and difficult injuries, with various complications that can lead to ventilation-perfusion (V/Q) mismatch and systemic hypoxia. We are presenting a case of a 53-year-old male with no chronic therapy who was admitted to the Intensive Care Unit due to severe respiratory failure after chest trauma. He developed a right-sided pneumothorax, and then a thoracic drain was placed. On admission, the patient was hemodynamically unstable and tachypneic. He was intubated and mechanically ventilated, febrile (38.9 °C) and unconscious. A lung CT showed massive non-ventilated areas, predominantly in the right lung, guiding repeated therapeutic and diagnostic bronchoalveolar lavages. He was ventilated with PEEP of 10 cmH2O with a FiO2 of 0.6-0.8. Empirical broad-spectrum antimicrobial therapy was immediately initiated. Both high FiO2 and moderate PEEP were maintained and adjusted according to the current blood gas values and oxygen saturation. He was weaned from mechanical ventilation, and non-invasive oxygenation was continued. After Stenotrophomonas maltophilia was identified and treated with sulfamethoxazole/trimethoprim, a regression of lung infiltrates was observed. In conclusion, both ventilatory and antibiotic therapy were needed to improve the oxygenation and outcome of the patient with S. maltophilia pneumonia and V/Q mismatch.

Assessment of lung hyperinflation in occupational chronic obstructive pulmonary disease: a multicentric cross-sectional study

Occupational exposure is associated with elevated morbidity and lower quality of life in patients with chronic obstructive pulmonary disease (COPD). Static hyperinflation is an independent risk factor for all-cause mortality in COPD and for COPD exacerbation. In a multicentre, cross-sectional study (BPROFETIO), we sought to analyse the relationship between static hyperinflation and occupational exposure in patients with COPD with or without occupational exposure.

MATERIAL AND METHODS

An overall 'whole working life' cumulative exposure index was calculated for occupational patients with COPD. Spirometry indices and lung volumes were measured according to the 2005 American Thoracic Society/European Respiratory Society guidelines.

RESULTS

After adjustment for age, sex, height, body mass index, smoking and coexposure, the analysis for each occupational hazard showed a higher risk for hyperinflation and FEV1 decline or progression of COPD or GOLD stage for patients with COPD exposed to non-metallic inorganic dusts.

CONCLUSION

Occupational exposures should be more investigated in clinical practice and studies as they contribute to the COPD heterogeneity and are associated for some with the development of a static hyperinflation; a condition that is known to have a negative impact on quality of life and survival.

Severe Air Pollution Exposure and Long-Term Health Outcomes

BACKGROUND

There is a large literature that documents the negative health implications of exposure to air pollution, particularly PM2.5. Much of this literature, however, relies on short-term cross-sectional data, which cannot establish a true causal link between pollution and health. There are also very few studies that document long- and very long-term effects.

PURPOSE

This study intends to estimate a causal relationship between exposure to severe air pollution and negative health outcomes that persist over long periods of time.

METHODS

We use a large longitudinal dataset that spans almost 2 decades and that allows us to not only document the persistence of negative health effects, but also a pattern of recovery from a severe pollution episode. We use multivariate regression methods to estimate a causal link between air pollution and health over time. A large pollution shock that occurred in 1997 in Indonesia is used as a natural experiment to pinpoint the true causal effects of pollution exposure and not mere correlations.

RESULTS

Exposure to an additional unit of pollution in 1997 leads to a loss of roughly six units of lung capacity and to an increase of 4.3% in the probability of being in poor general health, as measured ten years after the pollution exposure. These effects somewhat diminish over time, to a loss of roughly three units of lung capacity and to an increase of only about 3% in the probability of being in poor general health, as measured 17 years after exposure.

CONCLUSIONS

Our study finds significant health consequences of exposure to air pollution, which persist over long periods of time, with some patterns of recovery. Policymakers should pay special attention to such massive sources of pollution and try to mitigate these negative health consequences.

FVC, but not FEV1, is associated with clinical outcomes of asthma-COPD overlap

The effects of forced vital capacity (FVC) on clinical outcomes of asthma-chronic obstructive pulmonary diseases overlap (ACO) are still unknown. We conducted this study to examine the association of FVC on clinical outcomes in ACO. Data from the Korean COPD Subgroup Study cohort were analyzed. Patients who fulfilled the ACO criteria were included and grouped according to FVC changes, such as FVC-incline and FVC-decline. No significant differences were observed between the FVC-incline and FVC-decline groups in baseline clinical characteristics. In a year after, FVC-decline group experienced more moderate (47.1% vs. 36.8%, p = 0.02) and moderate-to-severe (49.8% vs. 39.6%, p = 0.03) acute exacerbations (AEs), compared to FVC-incline group. The frequency of moderate AEs (1.3 ± 2.1 vs. 0.9 ± 1.7, p = 0.03) and moderate-to-severe AEs (1.5 ± 2.5 vs. 1.1 ± 1.9, p = 0.04) were higher in the FVC-decline group than in the FVC-incline groups. After adjusting for confounding factors, FVC-decline group was associated with moderate AEs (odds ratio [OR] = 1.58; 95% confidence interval [CI] 1.02-2.44; p = 0.04), and moderate-to-severe AEs (OR = 1.56; 95% CI 1.01-2.41; p < 0.05) in ACO patients, which was not seen in FEV₁ changes. FVC changes are associated with clinical outcomes in ACO.

Role of pulmonary function testing in inflammatory bowel diseases (Review)

Inflammatory bowel disease (IBD) is a term used to describe chronic inflammatory entities of the gastrointestinal system with an unclear etiology. Extra-intestinal manifestations beyond the involvement of the gastrointestinal tract can also occur. Several studies have investigated the alterations of pulmonary function tests (PFTs) in patients with IBD. To the best of our knowledge, the present review article is the first to summarize all the types of PFTs that have been performed in patients with IBD. Contradictory data exist regarding the association of PFT alterations with disease activity. PFT abnormalities can develop in individuals with IBD who have no clear clinical signs or radiological evidence, suggesting that PFTs may be useful in detecting latent respiratory involvement. The most prevalent finding in the PFTs of adults and children with IBD is an impairment in the diffusing capacity for carbon monoxide, although evidence on the other tests, particularly spirometric values, and their connection with disease activity is inconsistent.

Air pollution enhance the progression of restrictive lung function impairment and diffusion capacity reduction: an elderly cohort study

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 (PM_2.5) 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 PM_2.5 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.

Isolated Elevation in Lung Residual Volume Is Associated With Airway Diseases

BACKGROUND

Residual volume (RV) is a derived lung compartment that correlates with air trapping in the context of air flow obstruction on spirometry. The significance of an isolated elevation in RV in the absence of other pulmonary function test (PFT) abnormalities is not well defined. We sought to assess the clinical and radiologic findings associated with isolated elevation in RV.

METHODS

We searched our out-patient PFT database at Mayo Clinic (Rochester, Minnesota) from 2016-2018 for adult patients with isolated elevation in RV. We defined isolated elevation in RV as RV ≥ upper limit of normal or ≥ 130% predicted with normal total lung capacity (TLC), spirometry, and diffusion capacity of the lung for carbon monoxide (D_LCO). We then matched this high-RV group by age and sex to an equal number of individuals with normal RV, TLC, spirometry, and D_LCO (normal-RV group).

RESULTS

We identified 169 subjects with isolated elevation in RV on PFTs, with a median age of 73 y; 55.6% were female, and median body mass index was 26.8 (vs 29.8 in the normal-RV group). The median RV was 3.08 L (134% predicted, interquartile range [IQR] 130-141) in the high-RV group and 2.26 L (99% predicted, IQR 90-109) in the normal-RV group (P < .001). Subjects with high RV were more likely to have smoked (54% vs 40%, P = .01) and almost twice as likely to have a maximum voluntary ventilation < 30 times the FEV₁ (21% vs 12%, P = .02). Clinically, asthma (21% vs 11%, P = .01) and non-tuberculous mycobacterial lung infections (12% vs 2%, P = .001) were more prevalent in the high-RV group. On chest computed tomography, bronchiectasis (31% vs 15%, P = .008), bronchial thickening or mucus plugging (46% vs 22%, P < .001), and emphysema (13% vs 5%, P = .046) were more common in the high-RV group.

CONCLUSIONS

Isolated elevation in RV on PFTs is a clinically relevant abnormality associated with airway-centered diseases.

Air Trapping and the Risk of COPD Exacerbation: Analysis From Prospective KOCOSS Cohort

Background and Aims

Air 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 Methods

To 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.

Results

Of 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).

Conclusions

In 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.

Impaired Spontaneous Baroreceptor Reflex Sensitivity in Patients With COPD Compared to Healthy Controls: The Role of Lung Hyperinflation

Background and Objectives: Patients with chronic obstructive pulmonary disease (COPD) are at increased risk for cardiovascular disease. This study aimed to investigate the relationship between pulmonary hyperinflation and baroreceptor reflex sensitivity (BRS), a surrogate for cardiovascular risk. Methods: 33 patients with COPD, free from clinical cardiovascular disease, and 12 healthy controls were studied. Participants underwent pulmonary function and non-invasive hemodynamic measurements. BRS was evaluated using the sequence method during resting conditions and mental arithmetic stress testing. Results: Patients with COPD had evidence of airflow obstruction [forced expiratory volume in 1 s predicted (FEV₁%) 26.5 (23.3-29.1) vs. 91.5 (82.8-100.8); P < 0.001; geometric means (GM) with 95% confidence interval (CI)] and lung hyperinflation [residual volume/total lung capacity (RV/TLC) 67.7 (64.3-71.3) vs. 41.0 (38.8-44.3); P < 0.001; GM with 95% CI] compared to controls. Spontaneous mean BRS (BRSmean) was significantly lower in COPD, both during rest [5.6 (4.2-6.9) vs. 12.0 (9.1-17.6); P = 0.003; GM with 95% CI] and stress testing [4.4 (3.7-5.3) vs. 9.6 (7.7-12.2); P < 0.001; GM with 95% CI]. Stroke volume (SV) was significantly lower in the patient group [-21.0 ml (-29.4 to -12.6); P < 0.001; difference of the means with 95% CI]. RV/TLC was found to be a predictor of BRS and SV (P < 0.05 for both), independent of resting heart rate. Conclusion: We herewith provide evidence of impaired BRS in patients with COPD. Hyperinflation may influence BRS through alteration of mechanosensitive vagal nerve activity.

Evaluation of spirometry-gated computed tomography to measure lung volumes in emphysema patients

Introduction

In emphysema patient being evaluated for bronchoscopic lung volume reduction (BLVR), accurate measurement of lung volumes is important. Total lung capacity (TLC) and residual volume (RV) are commonly measured by body plethysmography but can also be derived from chest computed tomography (CT). Spirometry-gated CT scanning potentially improves the agreement of CT and body plethysmography. The aim of this study was to compare lung volumes derived from spirometry-gated CT and “breath-hold-coached” CT to the reference standard: body plethysmography.

Methods

In this single-centre retrospective cohort study, emphysema patients being evaluated for BLVR underwent body plethysmography, inspiration (TLC) and expiration (RV) CT scan with spirometer guidance (“gated group”) or with breath-hold-coaching (“non-gated group”). Quantitative analysis was used to calculate lung volumes from the CT.

Results

200 patients were included in the study (mean±sd age 62±8 years, forced expiratory flow in 1 s 29.2±8.7%, TLC 7.50±1.46 L, RV 4.54±1.07 L). The mean±sd CT-derived TLC was 280±340 mL lower compared to body plethysmography in the gated group (n=100), and 590±430 mL lower for the non-gated group (n=100) (both p<0.001). The mean±sd CT-derived RV was 300±470 mL higher in the gated group and 700±720 mL higher in the non-gated group (both p<0.001). Pearson correlation factors were 0.947 for TLC gated, 0.917 for TLC non-gated, 0.823 for RV gated, 0.693 for RV non-gated, 0.539 for %RV/TLC gated and 0.204 for %RV/TLC non-gated. The differences between the gated and non-gated CT results for TLC and RV were significant for all measurements (p<0.001).

Conclusion

In severe COPD patients with emphysema, CT-derived lung volumes are strongly correlated to body plethysmography lung volumes, and especially for RV, more accurate when using spirometry gating.

Instructional Training Compared with Self-Study for Pulmonary Function Test Interpretation

Background

Pulmonary diseases have considerable prognostic relevance for all-cause mortality. Most patients with lung diseases such as chronic obstructive pulmonary disease are treated by general practitioners. Understanding the clinical consequences such as pulmonary hyperinflation or reduced diffusion capacity is important for the management and prognosis of patients with chronic respiratory disorders. Therefore, the interpretation of pulmonary function testing (PFT) results needs to see more emphasis in the medical education curriculum.

Objective

To develop PFT training for final-year medical students and to compare the efficacy of instructional training to self-reliant textbook study.

Methods

A two-armed randomized control trial compares learning outcomes in PFT interpretation. A total of 25 final-year medical students were selected at random into the 1) instructional training group or 2) self-reliant textbook study group on PFT interpretation. The learning time for both groups was 2 hours. The duration of the written pre- and post-training examinations was 60 minutes each. Both exams had a knowledge section (30 questions, maximum 120 points) and a skills section (11 case studies, maximum 75 points).

Results

The instructional training group acquired significantly more knowledge and, in particular, higher skill levels when compared with the self-reliant reading group. In the reading group, knowledge scores increased from 48 to 60% (12%) and skills scores increased from 14 to 22% (8%), whereas in the instructional group, knowledge increased from 47 to 71% (24%) and skills from 18 to 58% (40%). A multivariate analysis (Pillai’s Trace: 0.633; P < 0.001) as well as follow-up univariate analyses reveal that these differences are statistically significant (knowledge: F = 8.811, df = 1, P = 0.007; skills F = 33.965, df = 1, P < 0.001). Interestingly, there was no significant group effect in the pure knowledge gain about respiratory disorders per se.

Conclusion

The self-reliant study group was less able to translate their newly acquired knowledge into interpretation of comprehensive PFT reports. A mandatory 2-hour instructional training greatly enhances the students’ knowledge and skills about PFT interpretation. Obligatory PFT instructional training should therefore be included in the students’ curriculum.

The Value of Residual Volume/Total Lung Capacity as an Indicator for Predicting Postoperative Lung Function in Non-Small Lung Cancer

Chronic obstructive pulmonary disease (COPD) is one of the most frequently occurring concomitant diseases in patients with non-small cell lung cancer (NSCLC). It is characterized by small airways and the hyperinflation of the lung. Patients with hyperinflated lung tend to have more reserved lung function than conventionally predicted after lung cancer surgery. The aim of this study was to identify other indicators in predicting postoperative lung function after lung resection for lung cancer. Patients with NSCLC who underwent curative lobectomy with mediastinal lymph node dissection from 2017 to 2019 were included. Predicted postoperative FEV₁ (ppoFEV₁) was calculated using the formula: preoperative FEV₁ × (19 segments-the number of segments to be removed) ÷ 19. The difference between the measured postoperative FEV₁ and ppoFEV₁ was defined as an outcome. Patients were categorized into two groups: preserved FEV₁ if the difference was positive and non-preserved FEV₁, if otherwise. In total, 238 patients were included: 74 (31.1%) in the FEV₁ non-preserved group and 164 (68.9%) in the FEV₁ preserved group. The proportion of preoperative residual volume (RV)/total lung capacity (TLC) ≥ 40% in the FEV₁ non-preserved group (21.4%) was lower than in the preserved group (36.1%) (p = 0.03). In logistic regression analysis, preoperative RV/TLC ≥ 40% was related to postoperative FEV1 preservation. (adjusted OR, 2.02, p = 0.041). Linear regression analysis suggested that preoperative RV/TLC was positively correlated with a significant difference. (p = 0.004) Preoperative RV/TLC ≥ 40% was an independent predictor of preserved lung function in patients undergoing curative lobectomy with mediastinal lymph node dissection. Preoperative RV/TLC is positively correlated with postoperative lung function.

Clinical impact of long-term change in air trapping on pulmonary function and computed tomography parameters in chronic obstructive pulmonary disease

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).

CONCLUSION

Patients with COPD whose RV/TLC changed from normal to abnormal showed deterioration of pulmonary function and worsening of CT parameters simultaneously.

Quantitative Computed Tomography Assessment of Pectoralis and Erector Spinae Muscle Area and Disease Severity in Chronic Obstructive Pulmonary Disease Referred for Lung Volume Reduction

Patients with advanced chronic obstructive pulmonary disease (COPD) develop skeletal muscle loss (sarcopenia) that is associated with adverse clinical outcomes including mortality. We evaluated if thoracic muscle area is associated with clinical outcomes in patients with severe COPD. We analyzed consecutive patients with severe COPD undergoing evaluation for lung volume reduction from 2015 to 2019 (n = 117) compared to current and former smoking controls undergoing lung cancer screening with normal lung function (n = 41). Quantitative assessments of pectoralis muscle (PM) and erector spinae muscle (ESM) cross sectional area (CSA) were related to clinical outcomes including composite endpoints. Our results showed a reduction in PM CSA but not ESM CSA was associated with the severity of GOLD stage of COPD. Current smokers demonstrated reduced PM CSA which was similar to that in COPD patients who were GOLD stages 3 and 4. PM CSA was associated positively with FEV1, FEV₁% predicted, FVC, DLCO, and FEV₁/FVC ratio, and was associated negatively with the degree of radiologic emphysema. ESM correlated positively with DLCO, RV/TLC (a marker of hyperinflation), and correlated negatively with radiologic severity of emphysema. Kaplan-Meier analysis showed that reductions in PM but not ESM CSA was associated with the composite end point of mortality, need for lung volume reduction, or lung transplant. In conclusion, in well-characterized patients with severe COPD referred for lung volume reduction, PM CSA correlated with severity of lung disease, mortality, and need for advanced therapies. In addition to predicting clinical outcomes, targeting sarcopenia is a potential therapeutic approach in patients with severe COPD.

The determinants of dyspnoea evaluated by the mMRC scale: The French Palomb cohort

INTRODUCTION AND OBJECTIVE

Dyspnoea is a major symptom in COPD patients, but the determinants that could be associated with a higher dyspnoea mMRC score in COPD patients remain unclear. Our research aimed to study the determinants of dyspnoea at the threshold of 1, 2, 3 and 4 mMRC.

PATIENTS AND METHODS

Diagnosis of COPD was made using spirometry with post-bronchodilator FEV₁FVC<70%. An online questionnaire has been employed by pulmonologists to recruit COPD patients. The following variables were collected: age, gender, BMI, FEV₁, RV, IC, TLC, FRC, mMRC, frequency of exacerbations and comorbidities. The LASSO was used to select the variables associated with the mMRC dyspnoea scale in a subgroup (who had no missing IC, RV and FRC values) of 421 COPD patients defined by the previously mentioned variables.

RESULTS

One thousand nine hundred and sevety-three patients (65.3% males, average age=66±10, 38% current smokers) were included. Dyspnoea was correlated with a low FEV₁ and with the number of exacerbations in the past 12 months. Multivariate analysis showed that the determinants of dyspnoea(mMRC≥2) are: FEV₁: OR=3.71[2.86-4.82]; anxiety: OR=2.52[1.82-3.47]; cough: OR=1.94[1.57-2.40]; bronchiectasis: OR=1.84[1.03-3.29]; age: OR=1.80[1.45-2.24]; hyperinflation (RV/TLC): OR=1.68[1.34-2.11]; ischemic cardiopathy: OR=1.63[1.22-2.18]; hypertension: OR=1.52[1.21-1.91]; exacerbations (≥2): OR=1.41[1.10-1.81]; women: OR=1.39[1.10-1.74] and overweight: OR=1.33[1.06-1.67]. The subgroup analysis showed that: FEV₁: OR=3.47[1.96-6.12]; exacerbations (≥2) OR=2.31[1.33-4.17] and hyperinflation (IC/TLC) OR=0.57[0.35-0.85] were associated with higher dyspnoea (mMRC≥2).

CONCLUSION

Our results showed that dyspnoea is related to the severity of airflow limitation, gender, exacerbations, comorbidities and hyperinflation.

Assessing Static Lung Hyperinflation by Whole-Body Plethysmography, Helium Dilution, and Impulse Oscillometry System (IOS) in Patients with COPD

Purpose

Lung hyperinflation is a feature of chronic obstructive pulmonary disease (COPD) and can determine pivotal consequence on symptoms, exercise tolerance and quality of life. Despite the relevance of assessing lung hyperinflation, there is still no single consensus as to what volume should be taken into account. We investigate which spirometric measurement is more reliable in assessing static lung hyperinflation and which is more related with impulse oscillometry system (IOS) measurements in COPD.

Patients and Methods

Fifty-five COPD patients were enrolled. TLC, RV and RV:TLC ratio were obtained both with helium and plethysmography techniques. IOS measurements (X5, Fres and R5-R20) were performed. Pearson and Spearman correlation determined the relationships between the functional parameters that evaluate static hyperinflation (RV: TLC, TLC, RV) and IOS measurements.

Results

As expected, we reported a statistically significant difference between these two techniques in terms of mean percentage values of TLC (7.57 ± 3.26 L; p= 0.02) and RV (15.24 ± 7.51 L; p=0.04), while RV:TLC measured with the two methods was similar (5.21 ± 4.69%; p=0.27). The correlation analysis showed that IOS parameters, such as difference in resistance between 5 Hz and 20 Hz (R(5–20)) and resonant frequency (Fres), were positively correlated with RV:TLC ratio, while reactance at 5 Hz (X(5)) was negatively correlated with it. In particular, we pointed out a weak correlation between RV:TLC (%) (Pleth) and R(5–20) (r=0.3, p=0.04), Fres (r=0.3; p=0.03), while X5 had a mild correlation with RV:TLC (%) (r=−0.5;p<0.0001). Moreover, we noticed a strong relationship between RV:TLC (%)(He) and X5 (r=−0.7; p=0.0001) and a mild correlation between RV:TLC (%) (He) and Fres (r=0.4; p=0.003). Between R5-R20 and RV:TLC, there was a weak correlation (r=0.3; p=0.001). No correlation between TLC, RV (L,%) (both helium and Pleth derived) and IOS parameters (R(5–20), X5, Fres) was found.

Conclusion

RV:TLC can represent the most reliable parameter in the assessment of hyperinflation, considering the absence of significant difference in its measurement between the two techniques. IOS provides supplementary information in the assessment of static hyperinflation.

Prediction of air trapping or pulmonary hyperinflation by forced spirometry in COPD patients: results from COSYCONET

Background

Air trapping and lung hyperinflation are major determinants of prognosis and response to therapy in chronic obstructive pulmonary disease (COPD). They are often determined by body plethysmography, which has limited availability, and so the question arises as to what extent they can be estimated via spirometry.

Methods

We used data from visits 1–5 of the COPD cohort COSYCONET. Predictive parameters were derived from visit 1 data, while visit 2–5 data was used to assess reproducibility. Pooled data then yielded prediction models including sex, age, height, and body mass index as covariates. Hyperinflation was defined as ratio of residual volume (RV) to total lung capacity (TLC) above the upper limit of normal. (ClinicalTrials.gov identifier: NCT01245933).

Results

Visit 1 data from 1988 patients (Global Initiative for Chronic Obstructive Lung Disease grades 1–4, n=187, 847, 766, 188, respectively) were available for analysis (n=1231 males, 757 females; mean±sd age 65.1±8.4 years; forced expiratory volume in 1 s (FEV₁) 53.1±18.4 % predicted (% pred); forced vital capacity (FVC) 78.8±18.8 % pred; RV/TLC 0.547±0.107). In total, 7157 datasets were analysed. Among measures of hyperinflation, RV/TLC showed the closest relationship to FEV₁ % pred and FVC % pred, which were sufficient for prediction. Their relationship to RV/TLC could be depicted in nomograms. Even when neglecting covariates, hyperinflation was predicted by FEV₁ % pred, FVC % pred or their combination with an area under the curve of 0.870, 0.864 and 0.889, respectively.

Conclusions

The degree of air trapping/hyperinflation in terms of RV/TLC can be estimated in a simple manner from forced spirometry, with an accuracy sufficient for inferring the presence of hyperinflation. This may be useful for clinical settings, where body plethysmography is not available.

This proposed method allows estimation of hyperinflation in COPD by spirometry, obviating the need for body plethysmography or further techniques. Results are depicted in easily applicable nomograms that can be used in clinical practice.https://bit.ly/3c0tUNL

Multiple Stressor Effects of Radon and Phthalates in Children: Background Information and Future Research

The present paper reviews available background information for studying multiple stressor effects of radon (222Rn) and phthalates in children and provides insights on future directions. In realistic situations, living organisms are collectively subjected to many environmental stressors, with the resultant effects being referred to as multiple stressor effects. Radon is a naturally occurring radioactive gas that can lead to lung cancers. On the other hand, phthalates are semi-volatile organic compounds widely applied as plasticizers to provide flexibility to plastic in consumer products. Links of phthalates to various health effects have been reported, including allergy and asthma. In the present review, the focus on indoor contaminants was due to their higher concentrations and to the higher indoor occupancy factor, while the focus on the pediatric population was due to their inherent sensitivity and their spending more time close to the floor. Two main future directions in studying multiple stressor effects of radon and phthalates in children were proposed. The first one was on computational modeling and micro-dosimetric studies, and the second one was on biological studies. In particular, dose-response relationship and effect-specific models for combined exposures to radon and phthalates would be necessary. The ideas and methodology behind such proposed research work are also applicable to studies on multiple stressor effects of collective exposures to other significant airborne contaminants, and to population groups other than children.

Mixed Phenotype of Emphysema and Airway Wall Thickening Is Associated with Frequent Exacerbation in Chronic Obstructive Pulmonary Disease Patients

Objective

The presence of both emphysema and airway wall thickening determined via volumetric computed tomography (CT) is defined as mixed phenotype. The long-term clinical course of this phenotype has not been studied in depth. This study compared the mixed phenotype to other phenotypes of chronic obstructive pulmonary disease (COPD) patients.

Methods

COPD patients enrolled in the Korean Obstructive Lung Disease (KOLD) study from June 2005 to October 2015 were evaluated. The emphysema index and the percentage of bronchial mean wall area were calculated from volumetric CT scans. Patients with COPD were classified into four phenotypes using two cutoffs: emphysema index of 15% and median value of mean wall area (MWA%).

Results

Of 435 patients with COPD, 99 (22.8%) were defined as CT-normal type, 119 (27.4%) as emphysema-dominant type, 113 (26.0%) as airway-dominant type, and 104 (23.9%) as mixed type. The mixed phenotype showed the highest baseline total COPD Assessment Test (CAT) and St. George’s Respiratory Questionnaire (SGRQ) scores. Moreover, it had the highest proportion of patients experiencing exacerbation of COPD (50.0%), and had the lowest baseline FEV1. Lower BMI, GOLD stages III–IV, and mixed phenotype were significant factors associated with severe exacerbation frequency in univariate analyses. Multivariate analyses showed that lower BMI and CT phenotype were significant factors associated with severe exacerbation frequency. Compared to the CT-normal phenotype, the mixed phenotype was significantly associated with more frequent severe exacerbation (IRR 4.134, 95% CI: 1.135–15.057, P=0.031).

Conclusion

Patients with mixed phenotype are more symptomatic, have poorer pulmonary function, and are associated with more frequent severe exacerbation.

Lung air trapping lowers respiratory arousal threshold and contributes to sleep apnea pathogenesis in COPD patients with overlap syndrome

STUDY OBJECTIVES

Overlap syndrome occurs when obstructive sleep apnea (OSA) and chronic obstructive pulmonary disorder (COPD) coexist in the same patient. Although several studies highlighted the importance of clinical phenotyping in OSA, the trait contribution to OSA pathogenesis in overlap syndrome has not been investigated. With this pilot study, we aimed to measure OSA determinants and their relationship with functional respiratory parameters in a sample of patients with overlap syndrome. In particular, we hypothesize that patients with COPD have in the low arousal threshold a major contributor for the development of OSA.

METHODS

Ten consecutive non-hypercapnic COPD patients (body mass index<35 kg/m²) suffering from overlap syndrome with no other relevant comorbidities underwent a phenotyping polysomnography. Traits were measured with CPAP dial-downs.

RESULTS

Arousal threshold was found to be inversely associated to functional measures of lung air trapping and static hyperinflation. Particularly, correlations with residual volume (r² = 0.49, p =  0.024) and residual volume to total lung capacity ratio (r² = 0.48, p =  0.026) were evident. Only 20% of patients showed a high upper airway passive collapsibility as single pathological trait. In contrast, among those patients with multiple altered traits (6 out of 10), all had an elevated loop gain and 4 (∼65%) a low arousal threshold.

CONCLUSIONS

High loop gain and particularly low arousal threshold seem important contributors to OSA pathogenesis and severity in patients with COPD. Recognizing in COPD patients these features as key traits may open avenues for personalized medicine in the field of overlap syndrome.

Investigating the relationships among lung function variables in chronic obstructive pulmonary disease in men

Background

In patients with chronic obstructive pulmonary disease (COPD), the independent contributions of individual lung function variables to outcomes may be lower when they are modelled together if they are collinear. In addition, lung volume measurements may not be necessary after spirometry data have been obtained. However, these hypotheses depend on whether forced vital capacity (FVC) can predict total lung capacity (TLC). Moreover, the definitions of hyperinflation and air trapping according to lung function variables overlap and need be clarified. Therefore, the aim of this study was to evaluate the relationships among various lung function parameters to elucidate these issues.

Methods

Demographic data and 26 parameters of full lung function were measured in 94 men with COPD and analyzed using factor and correlation analyses.

Results

Factor analysis revealed five latent factors. Inspiratory capacity (IC)/TLC and residual volume (RV)/TLC were most strongly correlated with all other lung volumes. IC/TLC, RV/TLC, and functional residual capacity (FRC)/TLC were collinear and were potential markers of air trapping, whereas TLC%, FRC%, and RV% were collinear and were potential markers of hyperinflation. RV/TLC >0.4 (or IC/TLC <0.4) was comparable with the ratio of forced expiratory volume in one second (FEV₁) and FVC <0.7. FVC% and FEV₁% were poorly correlated with TLC%. The correlation study showed that TLC%, RV/TLC, and FEV₁% could be used to represent individual latent factors for hyperinflation, air trapping, inspiration, expiration, and obstruction. Combined with diffusion capacity%, these four factors could be used to represent comprehensive lung function.

Conclusions

This study identified collinear relationships among individual lung function variables and thus selecting variables with close relationships for correlation studies should be performed with caution. This study also differentiated variables for air trapping and lung hyperinflation. Lung volume measurements are still required even when spirometry data are available. Four out of 26 lung function variables from individual latent factors could be used to concisely represent lung function.

Chronic Obstructive Pulmonary Disease and the Optimal Timing of Lung Transplantation

Chronic obstructive pulmonary disease (COPD) accounts for the largest proportion of respiratory deaths worldwide and was historically the leading indication for lung transplantation. The success of lung transplantation procedures is measured as survival benefit, calculated as survival with transplantation minus predicted survival without transplantation. In chronic obstructive pulmonary disease, it is difficult to show a clear and consistent survival benefit. Increasing knowledge of the risk factors, phenotypical heterogeneity, systemic manifestations, and their management helps improve our ability to select candidates and list those that will benefit the most from the procedure.

The impact of low forced vital capacity on behavior restrictions in a population with airflow obstruction

Background

Recent studies have suggested that low forced vital capacity (FVC) is related to respiratory symptoms with various comorbid conditions that eventually lead to physical inactivity and may be applied to subjects with airflow obstruction (AO). Therefore, this study aimed to evaluate the association between low FVC and behavior restrictions in subjects with AO.

Methods

A cross-sectional study was performed using data from the Korea National Health and Nutrition Survey conducted between 2007 and 2015. Participants aged 40 to 79 years with spirometry-defined AO (pre-bronchodilator forced expiratory volume in one second/FVC <70%) were analyzed to evaluate the association between low FVC (defined as FVC <80% predicted) and behavior restrictions.

Results

A total of 3,345 participants with AO were included. The proportion of subjects with low FVC varied widely according to severity of airflow limitation (0.9%, 35.5%, and 85.1% in the mild, moderate, and severe-to-very-severe AO groups, respectively). Compared to the moderate AO group with normal FVC, those with low FVC were more likely to be older, to be never- or ex-smokers, to have larger waist size with higher body mass index, and to have comorbidities such as diabetes, hypertension, dyslipidemia, and osteoporosis. Low FVC was independently associated with behavior restrictions [adjusted prevalence ratio (aPR), 1.72; 95% confidence interval (CI), 1.43-2.06] among all participants with AO, and this was most prominent in those with moderate AO (aPR, 1.65; 95% CI, 1.27-2.13).

Conclusions

In subjects with moderate AO, low FVC was independently associated with behavior restrictions even after adjusting for confounding factors.

Resting hyperinflation and emphysema on the clinical course of COPD

The aim of this study is to clarify whether the combined evaluation of resting hyperinflation and emphysema confers any additional advantages in terms of predicting clinical outcomes in chronic obstructive pulmonary disease (COPD) patients. We included COPD patients from the Korean Obstructive Lung Disease (KOLD) cohort. Patients with a residual volume/total lung capacity (RV/TLC) over the upper limit of normal were defined as having resting hyperinflation, and those with an emphysema index >10% were defined as having emphysema. We investigated the impacts of resting hyperinflation and emphysema on exacerbations and mortality. A total of 310 COPD patients were analyzed over a mean of 61.1 months. After adjustment for covariates, resting hyperinflation was an independent predictor of earlier exacerbation (HR = 1.66, CI = 1.24–2.22), more frequent exacerbation (IRR = 1.35, CI = 1.01–1.81), and higher mortality (HR = 2.45, CI = 1.16–5.17) risk. Emphysema was also significantly associated with earlier exacerbation (HR = 1.64, CI = 1.15–2.35), and higher mortality (HR = 3.13, CI = 1.06–9.27) risk. Participants with both resting hyperinflation and emphysema had an additively higher risk of earlier exacerbations (HR = 1.71, 95% CI = 1.26–2.33) and mortality (HR = 3.75, 95% CI = 1.81–7.73) compared with those in other groups. In conclusion, resting hyperinflation and emphysema had additional worse impacts on exacerbations and mortality in COPD patients.

Automated MR-based lung volume segmentation in population-based whole-body MR imaging: correlation with clinical characteristics, pulmonary function testing and obstructive lung disease

OBJECTIVES

Whole-body MR imaging is increasingly utilised; although for lung dedicated sequences are often not included, the chest is typically imaged. Our objective was to determine the clinical utility of lung volumes derived from non-dedicated MRI sequences in the population-based KORA-FF4 cohort study.

METHODS

400 subjects (56.4 ± 9.2 years, 57.6% males) underwent whole-body MRI including a coronal T1-DIXON-VIBE sequence in inspiration breath-hold, originally acquired for fat quantification. Based on MRI, lung volumes were derived using an automated framework and related to common predictors, pulmonary function tests (PFT; spirometry and pulmonary gas exchange, n = 214) and obstructive lung disease.

RESULTS

MRI-based lung volume was 4.0 ± 1.1 L, which was 64.8 ± 14.9% of predicted total lung capacity (TLC) and 124.4 ± 27.9% of functional residual capacity. In multivariate analysis, it was positively associated with age, male, current smoking and height. Among PFT indices, MRI-based lung volume correlated best with TLC, alveolar volume and residual volume (RV; r = 0.57 each), while it was negatively correlated to FEV₁/FVC (r = 0.36) and transfer factor for carbon monoxide (r = 0.16). Combining the strongest PFT parameters, RV and FEV₁/FVC remained independently and incrementally associated with MRI-based lung volume (β = 0.50, p = 0.04 and β = - 0.02, p = 0.02, respectively) explaining 32% of the variability. For the identification of subjects with obstructive lung disease, height-indexed MRI-based lung volume yielded an AUC of 0.673-0.654.

CONCLUSION

Lung volume derived from non-dedicated whole-body MRI is independently associated with RV and FEV₁/FVC. Furthermore, its moderate accuracy for obstructive lung disease indicates that it may be a promising tool to assess pulmonary health in whole-body imaging when PFT is not available.

KEY POINTS

• Although whole-body MRI often does not include dedicated lung sequences, lung volume can be automatically derived using dedicated segmentation algorithms • Lung volume derived from whole-body MRI correlates with typical predictors and risk factors of respiratory function including smoking and represents about 65% of total lung capacity and 125% of the functional residual capacity • Lung volume derived from whole-body MRI is independently associated with residual volume and the ratio of forced expiratory volume in 1 s to forced vital capacity and may allow detection of obstructive lung disease.

Static hyperinflation is associated with ventilatory limitation and exercise tolerance in adult cystic fibrosis

INTRODUCTION

Lung hyperinflation is a potential mechanism limiting exercise tolerance. However, available data on the impact of static hyperinflation on exercise performance in adult cystic fibrosis are lacking. Furthermore, the relative contribution of both static and dynamic hyperinflation to exercise performance is unknown.

OBJECTIVES

The aim of this study was to determine the impact of static hyperinflation on exercise tolerance and lung dynamics in adult cystic fibrosis.

METHODS

Clinical data of 107 adult patients with cystic fibrosis, including pulmonary function, lung volumes and cardiopulmonary exercise from the Toronto Cystic Fibrosis database, were collected and analyzed. Patients were classified as having static hyperinflation with a residual volume to total lung capacity (RV/TLC) ratio of 30% or greater.

RESULTS

Patients with static hyperinflation demonstrated a significant reduction in exercise performance [peak oxygen uptake (% predicted) 70 ± 17 vs 80 ± 17; P = .006] and were more likely to experience ventilatory limitation when exercising (Fisher's exact test P < .001). Correlation analysis showed significant relationships between measures of static hyperinflation [RV/TLC ratio (%)] and exercise performance [peak oxygen uptake (% predicted); r = -.38, P < .001] and dynamic hyperinflation (r = -.35, P < .001). Multiple linear regression showed that the contribution of static hyperinflation to exercise performance [peak oxygen uptake (% predicted)] was greater than that of airway obstruction (forced expiratory volume in 1 second).

CONCLUSION

Clinicians working with this patient group in a pulmonary rehabilitation or health care setting may wish to consider using measures of static hyperinflation as end points to determine program or treatment efficacy.

Relationship between exercise endurance and static hyperinflation in a post hoc analysis of two clinical trials in patients with COPD

Background

Lung hyperinflation and exercise intolerance are hallmarks of chronic obstructive pulmonary disease (COPD). However, their relationship remains uncertain. A combined analysis of two placebo-controlled, randomized studies examined the effects of the long-acting muscarinic antagonist umeclidinium (UMEC) and long-acting β₂-agonist vilanterol (VI) separately and in combination on static hyperinflation, exercise endurance time (EET), and their relationship in patients with COPD.

Methods

Patients with moderate-to-severe stable COPD and resting functional residual capacity >120% predicted were randomized to UMEC/VI 62.5/25 μg, UMEC 62.5 μg, VI 25 μg, or placebo for 12 weeks. Inspiratory capacity (IC), residual volume (RV), total lung capacity (TLC), and EET in an endurance shuttle-walk test were measured. In this post hoc analysis, IC/TLC, RV/TLC, and IC were used as hyperinflation markers.

Results

After 12 weeks, UMEC/VI and UMEC and VI showed significant improvements in hyperinflation versus placebo when measured by absolute change from baseline in IC/TLC (trough and 3 hours postdose [P≤0.011]). UMEC/VI showed significant improvements versus UMEC and VI in absolute changes in IC/TLC (trough and 3 hours postdose [P≤0.001]). Statistical significance for comparisons with placebo and between treatments for absolute changes in IC and percentage changes in RV/TLC followed similar patterns to those for absolute changes in IC/TLC. UMEC/VI showed significant improvements in EET versus placebo at day 2 and week 12, measured as change from baseline in seconds (P≤0.002) and as a percentage from baseline (P≤0.005). There was a lack of evidence to suggest a correlation between improvements in static hyperinflation and EET at any time point.

Conclusion

Although the dual bronchodilator UMEC/VI demonstrated greater improvements in static hyperinflation markers than UMEC or VI and significant improvements in exercise endurance, no direct relationship was observed between static hyperinflation and exercise endurance.

The physiological basis and clinical significance of lung volume measurements

From a physiological standpoint, the lung volumes are either dynamic or static. Both subclasses are measured at different degrees of inspiration or expiration; however, dynamic lung volumes are characteristically dependent on the rate of air flow. The static lung volumes/capacities are further subdivided into four standard volumes (tidal, inspiratory reserve, expiratory reserve, and residual volumes) and four standard capacities (inspiratory, functional residual, vital and total lung capacities). The dynamic lung volumes are mostly derived from vital capacity. While dynamic lung volumes are essential for diagnosis and follow up of obstructive lung diseases, static lung volumes are equally important for evaluation of obstructive as well as restrictive ventilatory defects. This review intends to update the reader with the physiological basis, clinical significance and interpretative approaches of the standard static lung volumes and capacities.

Oxygen therapy in COPD patients with isolated nocturnal hypoxemia; comparison of quality of life and sleep between bronchitis and emphysema phenotype: A prospective observational study

BACKGROUND

COPD is a heterogeneous disease composed by two main phenotypes: bronchitis (COPDb) and emphysema (COPDe) with different clinical presentation, physiology, imaging, response to therapy and decline in lung function. The aim of this study is to evaluate whether nocturnal hypoxemic COPDb and COPDe have a different behaviour during sleep and the effect of nocturnal oxygen supplementation (nO₂LT).

MATERIALS AND METHODS

75 COPDb and 120 COPDe were enrolled. All patients performed polysomnography, Pittsburgh and Maugeri Foundation Respiratory Failure questionnaire, and pulmonary function before and after six months of nO₂LT.

RESULTS

At baseline, compared to COPDb, COPDe have decreased sleep efficiency (SE) (67.5±6% vs. 76.9±3% p<0.05) and higher arousals (A/I) (18.1±3 event/h vs. 8.7±1 event/h p<0.05). Oxygen desaturation index (ODI) was increased during REM (7.1±1 event/h vs. 2.3±0.5 event/h p<0.05). nO₂LT in COPDe improves SE (77±4% vs. 67.5±6% p<0.05) and decreases A/I (9±5 event/h vs. 18.1±3 event/h p<0.05). ODI during REM (3.5±2 event/h vs. 7.1±1 p<0.05) decreases and quality of life (QoL) improves (MFR-28 total 56±22 vs 45±20 p<0.05), due to an improvement in cognitive abilities (45±30 vs 33±31 p<0.05) and daily activities (61±29 vs 53±21 p>0.05). In COPDb nO₂LT reduces ST90 (15±6% vs. 43±8% p<0.05) less than in COPDe (15±6% vs. 8±4% p<0.05); improves A/I (10±2 event/h vs. 8.7±1 p<0.05) and there is no evidence of an improvement in QoL.

CONCLUSIONS

Six months of nO₂LT improve quality of life in COPDe, not in COPDb. We found a difference in sleep quality between COPDe and COPDb.

Plasma Inflammatory Cytokine IL-4, IL-8, IL-10, and TNF-α Levels Correlate with Pulmonary Function in Patients with Asthma-Chronic Obstructive Pulmonary Disease (COPD) Overlap Syndrome

Background

The aim of this study was to investigate the plasma inflammatory cytokine levels and their correlations with pulmonary function in patients with asthma-chronic obstructive pulmonary disease overlap syndrome (ACOS).

Material/Methods

Between January 2013 and December 2014, a total of 96 patients with asthma, acute exacerbation of chronic obstructive pulmonary disease (AECOPD), or ACOS were enrolled, and 35 healthy people were included as a control group. Fasting plasma interleukin (IL)-4, IL-8, IL-10, and tumor necrosis factor alpha (TNF-α) levels were detected using enzyme-linked immunosorbent assay (ELISA). Correlations between the plasma inflammatory cytokine levels and forced expiratory volume in 1 second (FEV1), FEV1/predicted value ratio (FEV1%pred), and FEV1/forced vital capacity (FVC) were analyzed.

Results

IL-4 and IL-8 levels showed statistically significant differences among the 3 groups of patients (both P<0.001); IL-4 level was significantly lower, while IL-8 level was significantly higher in the AECOPD group and ACOS group than those in the asthma group (all P<0.05). IL-10 level and TNF-α level were significantly different among the 3 patient groups (both P<0.001). IL-10 level was significantly different between each of the 2 groups (all P<0.001). TNF-α level in the asthma group was higher than in the AECOPD group and ACOS group (both P<0.001). IL-4 and IL-10 were positively and IL-8 and TNF-α were negatively related with FEV1, FEV1%pred, and FEV1/FVC.

Conclusions

Plasma levels of inflammatory cytokines IL-4, IL-8, IL-10, and TNF-α are related with severity of airway diseases and could be potential markers for the evaluation of asthma, COPD, and ACOS.