Exertional dyspnoea in COPD: the clinical utility of cardiopulmonary exercise testing

Physiological effects of nasal high flow therapy during exercise in patients with chronic obstructive pulmonary disease: A crossover randomised controlled trial

BACKGROUND

Nasal high flow (NHF) has been proposed to sustain high intensity exercise in people with COPD, but we have a poor understanding of its physiological effects in this clinical setting.

RESEARCH QUESTION

What is the effect of NHF during exercise on dynamic respiratory muscle function and activation, cardiorespiratory parameters, endurance capacity, dyspnoea and leg fatigue as compared to control intervention.

STUDY DESIGN AND METHODS

Randomized single-blind crossover trial including COPD patients. Two constant workload exercise testing were performed at 75% of peak power with NHF (30L/min, 34°C) or with control intervention. Pressure time product of the transdiaphragmatic pressure (PTPdi/min) and other physiological measurements were continuously monitored. Dyspnoea and lower limb fatigue were assessed using the 10-Borg scale.

RESULTS

14 patients with severe obstruction (median FEV1: 40 (IQR 28 to 52) %) were included. Their median age was 70 (IQR 57 to 72) years. At isotime, NHF had little to no effect on PTPdi/min (MD -15cmH2O.s/min, 95% CI -62 to 33) but increased tidal volume (MD 77mL, 95% CI 21 to 133). NHF also improved endurance capacity (MD 20s, 95% CI 2 to 40) and dyspnoea at isotime (MD -1.1, 95% CI -2.1 to -0.1). NHF had no or uncertain effect on other outcomes.

CONCLUSION

NHF has little to no effect on dynamic respiratory muscle function and activation but improves Vt. It leads to a trivially small increase in endurance capacity but a worthwhile improvement in dyspnoea. NHF may be beneficial for individuals experiencing critical inspiratory constraints and significant dyspnoea.

Transitioning from stress electrocardiogram to cardiopulmonary exercise testing: a paradigm shift toward comprehensive medical evaluation of exercise function

Cardiopulmonary exercise testing (CPET) has emerged as a powerful diagnostic tool, providing comprehensive physiological insights into the integrated function of cardiovascular, respiratory, and metabolic systems. Exploiting physiological interactions, CPET allows in-depth diagnostic insights. CPET performance entrains several complexities. Interpreting CPET data can be challenging, requiring significant physiological expertise. The advent of artificial intelligence (AI) has introduced a transformative approach to CPET interpretation, enhancing accuracy, efficiency, and clinical decision-making. This review article explores the current state of AI applications in CPET, highlighting AI's potential to replace the traditional stress electrocardiogram (ECG) test as the preferred diagnostic tool in preventive medicine and medical screening. The article discusses the underlying principles of AI, its integration into CPET interpretation, and the associated benefits, including improved diagnostic accuracy, reduced interobserver variability, and expedited decision-making. Additionally, it addresses the challenges and considerations surrounding the implementation of AI in CPET such as data quality, model interpretability, and ethical concerns. The review concludes by emphasizing the significant promise of AI-assisted CPET interpretation in revolutionizing preventive medicine and medical screening settings and enhancing patient care.

[Cardiopulmonary exercise testing: Key practical aspects]

Functional exercise testing (FET) assesses an individual's capacity to adapt to effort and identifies limiting factors, particularly dyspnea. It orients therapeutic choices, predicts the progression of chronic pathologies, and estimates preoperative risks, at times contraindicating surgery. The aim of this article is to provide a summary of the specific indications for functional exercise testing, test protocol selection, test equipment, appropriate personnel, and patient and test safety. This article is intended for healthcare professionals conducting or considering functional exercise testing.

Cardiopulmonary Exercise Testing, Rehabilitation, and Exercise Training in Postpulmonary Embolism

Long-term exercise intolerance and functional limitations are common after an episode of acute pulmonary embolism (PE), despite 3 to 6 months of anticoagulation. These persistent symptoms are reported in more than half of the patients with acute PE and are referred as "post-PE syndrome." Although these functional limitations can occur from persistent pulmonary vascular occlusion or pulmonary vascular remodeling, significant deconditioning can be a major contributing factor. Herein, the authors review the role of exercise testing to elucidate the mechanisms of exercise limitations to guide next steps in management and exercise training for musculoskeletal deconditioning.

Clinical features and associated factors of impaired ventilatory efficiency: findings from the ECOPD study in China

BACKGROUND

Impaired ventilatory efficiency during exercise is a predictor of mortality in chronic obstructive pulmonary disease. However, little is known about the clinical features and associated factors of impaired ventilatory efficiency in China.

METHODS

We conducted a cross-sectional community-based study in China and collected demographic and clinical information, cardiopulmonary exercise testing, spirometry, and CT data. Impaired ventilatory efficiency was defined by a nadir ventilatory equivalent for CO2 production above the upper limit of normal. Multivariable linear and logistic regression models were used to explore the clinical features and associated factors of impaired ventilatory efficiency.

RESULTS

The final analyses included 941 subjects, 702 (74.6%) of whom had normal ventilatory efficiency and 239 (25.4%) had impaired ventilatory efficiency. Participants with impaired ventilatory efficiency had more chronic respiratory symptoms, poorer lung function and exercise capacity, and more severe emphysema (natural logarithm transformation of the low-attenuation area of the lung with attenuation values below -950 Hounsfield units, logLAA-950: 0.19±0.65 vs -0.28±0.63, p<0.001) and air trapping (logLAA-856: 1.03±0.65 vs 0.68±0.70, p<0.001) than those with normal ventilatory efficiency. Older age (60-69 years, OR 3.10 (95% CI 1.33 to 7.21), p=0.009 and 70-80 years, OR 6.48 (95% CI 2.56 to 16.43), p<0.001 vs 40-49 years) and smoking (former, OR 3.19 (95% CI 1.29 to 7.86), p=0.012; current, OR 4.27 (95% CI 1.78 to 10.24), p=0.001 vs never) were identified as high risk factors of impaired ventilatory efficiency.

CONCLUSIONS

Impaired ventilatory efficiency was associated with poorer respiratory characteristics. Longitudinal studies are warranted to explore the progression of individuals with impaired ventilatory efficiency.

Identifying limitations to exercise with incremental cardiopulmonary exercise testing: a scoping review

Cardiopulmonary exercise testing (CPET) is a comprehensive and invaluable assessment used to identify the mechanisms that limit exercise capacity. However, its interpretation remains poorly standardised. This scoping review aims to investigate which limitations to exercise are differentiated by the use of incremental CPET in literature and which criteria are used to identify them. We performed a systematic, electronic literature search of PubMed, Embase, Cochrane CENTRAL, Web of Science and Scopus. All types of publications that reported identification criteria for at least one limitation to exercise based on clinical parameters and CPET variables were eligible for inclusion. 86 publications were included, of which 57 were primary literature and 29 were secondary literature. In general, at the level of the cardiovascular system, a distinction was often made between a normal physiological limitation and a pathological one. Within the respiratory system, ventilatory limitation, commonly identified by a low breathing reserve, and gas exchange limitation, mostly identified by a high minute ventilation/carbon dioxide production slope and/or oxygen desaturation, were often described. Multiple terms were used to describe a limitation in the peripheral muscle, but all variables used to identify this limitation lacked specificity. Deconditioning was a frequently mentioned exercise limiting factor, but there was no consensus on how to identify it through CPET. There is large heterogeneity in the terminology, the classification and the identification criteria of limitations to exercise that are distinguished using incremental CPET. Standardising the interpretation of CPET is essential to establish an objective and consistent framework.

Comparable Ventilatory Inefficiency at Maximal and Submaximal Performance in COPD vs. CHF subjects: An Innovative Approach

BACKGROUND

Currently, excess ventilation has been grounded under the relationship between minute-ventilation/carbon dioxide output ( V ˙ E - V ˙ CO 2 ). Alternatively, a new approach for ventilatory efficiency ( η E V ˙ ) has been published.

OBJECTIVE

Our main hypothesis is that comparatively low levels of η E V ˙ between chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD) are attainable for a similar level of maximum and submaximal aerobic performance, conversely to long-established methods ( V ˙ E - V ˙ CO 2 slope and intercept).

METHODS

Both groups performed lung function tests, echocardiography, and cardiopulmonary exercise testing. The significance level adopted in the statistical analysis was 5%. Thus, nineteen COPD and nineteen CHF-eligible subjects completed the study. With the aim of contrasting full values of V ˙ E - V ˙ CO 2 and η V ˙ E for the exercise period (100%), correlations were made with smaller fractions, such as 90% and 75% of the maximum values.

RESULTS

The two groups attained matched characteristics for age (62±6 vs. 59±9 yrs, p>.05), sex (10/9 vs. 14/5, p>0.05), BMI (26±4 vs. 27±3 Kg m2, p>0.05), and peak V ˙ O 2 (72±19 vs. 74±20 %pred, p>0.05), respectively. The V ˙ E - V ˙ CO 2 slope and intercept were significantly different for COPD and CHF (27.2±1.4 vs. 33.1±5.7 and 5.3±1.9 vs. 1.7±3.6, p<0.05 for both), but η V ˙ E average values were similar between-groups (10.2±3.4 vs. 10.9±2.3%, p=0.462). The correlations between 100% of the exercise period with 90% and 75% of it were stronger for η V ˙ E (r>0.850 for both).

CONCLUSION

The η V ˙ E is a valuable method for comparison between cardiopulmonary diseases, with so far distinct physiopathological mechanisms, including ventilatory constraints in COPD.

Effect of internet-based pulmonary rehabilitation on physical capacity and health-related life quality in patients with chronic obstructive pulmonary disease-a systematic review and meta-analysis

PURPOSE

Pulmonary rehabilitation (PR) is now recognized as the most effective treatments for individuals with chronic obstructive pulmonary disease (COPD), internet-based PR arises a promising method. The aim of this study was to conduct a systematic review and meta-analysis for assessing the effect of internet-based PR programs on physical capacity and health-related quality of life in patients with COPD.

MATERIALS AND METHODS

Randomized controlled trials were identified through systematically searches in PubMed, EMBASE, web of science, CENTRAL, Cochrane Library, and Google Scholar databases.

RESULTS

Twelve studies (1433 patients) were included. For physical capacity, there was no significant difference between groups was found according to the 6-min walk test (6MWT) (MD10.42, 95% CI -2.92 to 23.77, p = 0.13, I2 = 0%). For the health-related quality of life, no significant difference between groups was found regarding the St George's Respiratory Questionnaire (SGRQ) (MD -0.64, 95% CI -3.52 to 2.23, p = 0.66), COPD assessment test (CAT)(MD -0.34, 95% CI -1.62 to 0.94, p = 0.60), modified Medical Research Council scale (mMRC)(MD 0.17, 95% CI -0.06 to 0.39, p = 0.15) and Chronic Respiratory Questionnaire (CRQ)(MD 1.32 95% CI -5.88 to 8.53, p = 0.72).

CONCLUSIONS

This study has established the potential for delivery of PR via the internet in demonstrating non-inferiority of physical capacity and health-related quality of life (HRQoL) compared with conventional PR.IMPLICATIONS FOR REHABILITATIONLong-term rehabilitation training for patients with chronic obstructive pulmonary disease needs a more convenient and feasible way.In this study, internet-based rehabilitation showed similar effects as conventional rehabilitation on physical activity and health-related quality of life.Internet-based rehabilitation strategies would be helpful for this population.All internet-based rehabilitation strategies should be simple and sustainable.

How to interpret a cardiorespiratory fitness assessment - Key measures that provide the best picture of health, disease status and prognosis

Graded exercise testing is a widely accepted tool for revealing cardiac ischemia and/or arrhythmias in clinical settings. Cardiopulmonary exercise testing (CPET) measures expired gases during a graded exercise test making it a versatile tool that helps reveal underlying physiologic abnormalities that are in many cases only present with exertion. It also characterizes one's health status and clinical trajectory, informs the therapeutic plan, evaluates the efficacy of therapy, and provides submaximal and maximal information that can be used to tailor an exercise intervention. Practitioners can also modify the mode and protocol to allow individuals of all ages, fitness levels, and most disease states to perform a CPET. When used to its full potential, CPET can be a key tool used to optimize care in primary and secondary prevention settings.

Cardiopulmonary exercise testing criteria for advanced therapies in patients with heart failure

Many cardiology associations endorse the role of the cardiopulmonary exercise test (CPET) to define the severity of impairment of functional capacity in individuals with heart failure with reduced ejection fraction (HFrEF) and when evaluating the need for advanced therapies for these patients. The focus of the CPET within the cardiology community has been on peak volume of oxygen uptake (VO2). However, several CPET variables are associated with outcomes in individuals with and without chronic disease and can inform clinical decisions in individuals with HFrEF. In this manuscript, we will review the normal cardiopulmonary response to a graded exercise test and review current guideline recommendations relative to CPET in patients with HFrEF.

Effect of maximum exercise on left ventricular deformation and its correlation with cardiopulmonary exercise capacity in competitive athletes

BACKGROUND

Global longitudinal strain (GLS) and global myocardial work index (GWI) allow early detection of subclinical changes in left ventricular (LV) systolic function. The aim of the study was to investigate the immediate effects of maximum physical exercise by different exercise testing methods on early post exercise LV deformation parameters in competitive athletes and to analyze their correlation with cardiopulmonary exercise capacity.

METHODS

To reach maximum physical exercise, cardiopulmonary exercise testing (CPET) was performed by semi-recumbent ergometer in competitive handball players (n = 13) and by treadmill testing in competitive football players (n = 19). Maximum oxygen uptake (VO2max) indexed to body weight (relative VO2max) was measured in all athletes. Transthoracic echocardiography and blood pressure measurements were performed at rest and 5 min after CPET in all athletes. GLS, GWI and their changes before and after CPET (ΔGLS, ΔGWI) were correlated with (relative) VO2max.

RESULTS

In handball and football players, GLS and GWI did not differ significantly before and after CPET. There were no significant correlations between GLS and relative VO2max, but moderate correlations were found between ΔGWI and relative VO2max in handball (r = 0.631; P = 0.021) and football players (r = 0.592; P = 0.008). Furthermore, handball (46.7 ml/min*kg ± 4.7 ml/min*kg vs. 37.4 ml/min*kg ± 4.2; P = 0.004) and football players (58.3 ml/min*kg ± 3.7 ml/min*kg vs. 49.7 ml/min*kg ± 6.8; P = 0.002) with an increased ΔGWI after CPET showed a significant higher relative VO2max.

CONCLUSION

Maximum physical exercise has an immediate effect on LV deformation, irrespective of the used testing method. The correlation of relative VO2max with ΔGWI in the early post exercise period, identifies ΔGWI as an echocardiographic parameter for characterizing the current individual training status of athletes.

Dynamic Ventilatory Reserve During Incremental Exercise: Reference Values and Clinical Validation in Chronic Obstructive Pulmonary Disease

Rationale: Ventilatory demand-capacity imbalance, as inferred based on a low ventilatory reserve, is currently assessed only at peak cardiopulmonary exercise testing (CPET). Peak ventilatory reserve, however, is poorly sensitive to the submaximal, dynamic mechanical ventilatory abnormalities that are key to dyspnea genesis and exercise intolerance. Objectives: After establishing sex- and age-corrected norms for dynamic ventilatory reserve at progressively higher work rates, we compared peak and dynamic ventilatory reserve for their ability to expose increased exertional dyspnea and poor exercise tolerance in mild to very severe chronic obstructive pulmonary disease (COPD). Methods: We analyzed resting functional and incremental CPET data from 275 controls (130 men, aged 19-85 yr) and 359 Global Initiative for Chronic Obstructive Lung Disease patients with stage 1-4 obstruction (203 men) who were prospectively recruited for previous ethically approved studies in three research centers. In addition to peak and dynamic ventilatory reserve (1 - [ventilation / estimated maximal voluntary ventilation] × 100), operating lung volumes and dyspnea scores (0-10 on the Borg scale) were obtained. Results: Dynamic ventilatory reserve was asymmetrically distributed in controls; thus, we calculated its centile distribution at every 20 W. The lower limit of normal (lower than the fifth centile) was consistently lower in women and older subjects. Peak and dynamic ventilatory reserve disagreed significantly in indicating an abnormally low test result in patients: whereas approximately 50% of those with a normal peak ventilatory reserve showed a reduced dynamic ventilatory reserve, the opposite was found in approximately 15% (P < 0.001). Irrespective of peak ventilatory reserve and COPD severity, patients who had a dynamic ventilatory reserve below the lower limit of normal at an isowork rate of 40 W had greater ventilatory requirements, prompting earlier attainment of critically low inspiratory reserve. Consequently, they reported higher dyspnea scores, showing poorer exercise tolerance compared with those with preserved dynamic ventilatory reserve. Conversely, patients with preserved dynamic ventilatory reserve but reduced peak ventilatory reserve reported the lowest dyspnea scores, showing the best exercise tolerance. Conclusions: Reduced submaximal dynamic ventilatory reserve, even in the setting of preserved peak ventilatory reserve, is a powerful predictor of exertional dyspnea and exercise intolerance in COPD. This new parameter of ventilatory demand-capacity mismatch may enhance the yield of clinical CPET in the investigation of activity-related breathlessness in individual patients with COPD and other prevalent cardiopulmonary diseases.

Laboratory and free-living gait performance in adults with COPD and healthy controls

Background

Gait characteristics are important risk factors for falls, hospitalisations and mortality in older adults, but the impact of COPD on gait performance remains unclear. We aimed to identify differences in gait characteristics between adults with COPD and healthy age-matched controls during 1) laboratory tests that included complex movements and obstacles, 2) simulated daily-life activities (supervised) and 3) free-living daily-life activities (unsupervised).

Methods

This case-control study used a multi-sensor wearable system (INDIP) to obtain seven gait characteristics for each walking bout performed by adults with mild-to-severe COPD (n=17; forced expiratory volume in 1 s 57±19% predicted) and controls (n=20) during laboratory tests, and during simulated and free-living daily-life activities. Gait characteristics were compared between adults with COPD and healthy controls for all walking bouts combined, and for shorter (≤30 s) and longer (>30 s) walking bouts separately.

Results

Slower walking speed (-11 cm·s-1, 95% CI: -20 to -3) and lower cadence (-6.6 steps·min-1, 95% CI: -12.3 to -0.9) were recorded in adults with COPD compared to healthy controls during longer (>30 s) free-living walking bouts, but not during shorter (≤30 s) walking bouts in either laboratory or free-living settings. Double support duration and gait variability measures were generally comparable between the two groups.

Conclusion

Gait impairment of adults with mild-to-severe COPD mainly manifests during relatively long walking bouts (>30 s) in free-living conditions. Future research should determine the underlying mechanism(s) of this impairment to facilitate the development of interventions that can improve free-living gait performance in adults with COPD.

Cardiopulmonary Exercise Testing, Rehabilitation, and Exercise Training in Postpulmonary Embolism

Long-term exercise intolerance and functional limitations are common after an episode of acute pulmonary embolism (PE), despite 3 to 6 months of anticoagulation. These persistent symptoms are reported in more than half of the patients with acute PE and are referred as "post-PE syndrome." Although these functional limitations can occur from persistent pulmonary vascular occlusion or pulmonary vascular remodeling, significant deconditioning can be a major contributing factor. Herein, the authors review the role of exercise testing to elucidate the mechanisms of exercise limitations to guide next steps in management and exercise training for musculoskeletal deconditioning.

Questionnaire for diagnosing asthma-COPD overlap in COPD: Development of ACO screening questionnaire (ACO-Q)

BACKGROUND

The considerable prevalence and worse outcomes of asthma-COPD overlap (ACO) in COPD have been reported, and optimal introduction of ICS is essential for ACO. However, diagnostic criteria for ACO consist of multiple laboratory tests, which is challenging during this COVID-19 era. The purpose of this study was to create a simple questionnaire to diagnose ACO in patients with COPD.

METHODS

Among 100 COPD patients, 53 were diagnosed with ACO based on the Japanese Respiratory Society Guidelines for ACO. Firstly, 10 candidate questionnaire items were generated and further selected by a logistic regression model. An integer-based scoring system was generated based on the scaled estimates of items.

RESULTS

Five items, namely a history of asthma, wheezing, dyspnea at rest, nocturnal awakening, and weather- or season-dependent symptoms, contributed significantly to the diagnosis of ACO in COPD. History of asthma was related to FeNO >35 ppb. Two points were assigned to history of asthma and 1 point to other items in the ACO screening questionnaire (ACO-Q), and the area under the receiver operating characteristic curve was 0.883 (95% CI: 0.806-0.933). The best cutoff point was 1 point, and the positive predictive value was 100% at a cutoff of 3 points or higher. The result was reproducible in the validation cohort of 53 patients with COPD.

CONCLUSIONS

A simple questionnaire, ACO-Q, was developed. Patients with scores ≥3 could be reasonably recommended to be treated as ACO, and additional laboratory testing would be recommended for patients with 1 and 2 points.

The fully engaged inspiratory muscle training reduces postoperative pulmonary complications rate and increased respiratory muscle function in patients with upper abdominal surgery: a randomized controlled trial

BACKGROUND

Upper abdominal surgical treatment may reduce respiratory muscle function and mucociliary clearance, which might be a cause of postoperative pulmonary complications (PPCs). Threshold inspiratory muscle training (IMT) may serve as an effective modality to improve respiratory muscle strength and endurance in patients. However, whether this training could help patients with upper abdominal surgery remains to be determined. The aim of the present investigation was to determine the effect of a fully engaged IMT on PPCs and respiratory function in patients undergoing upper abdominal surgery. We hypothesized that the fully engaged IMT could reduce PPCs and improve respiratory muscle function in patients with upper abdominal surgery.

METHODS

This is a randomized controlled trial (RCT) with 28 patients who underwent upper abdominal surgery. Patients were randomly assigned to the control (CLT) group or the IMT group. The CTL group received regular health care. The IMT group received 3 weeks of IMT with 50% of MIP as the initial intensity before the operation. The intensity of MIP increased by 5-10% per week. The IMT was continued for 4 weeks after the operation. The study investigated the outcomes including PPCs, respiratory muscle strength, diaphragmatic function, cardiopulmonary function, and quality of life (QoL).

RESULTS

We found that IMT improved respiratory muscle strength and diaphragmatic excursion. IMT also had a beneficial effect on the incidence of postoperative pulmonary complications (PPCs) compared to CLT care.

CONCLUSION

The results from this study revealed that IMT provided positive effects on parameters associated with the respiratory muscle function and reduced the incidence of PPCs. We propose that fully engaged IMT should be a part of clinical management in patients with upper abdominal surgery.KEY MESSAGESThe fully engaged inspiratory muscle training reduces postoperative pulmonary complications rate in patients with upper abdominal surgery.The fully engaged inspiratory muscle training increases maximal inspiratory pressure in patients with upper abdominal surgery.The fully engaged inspiratory muscle training increases diaphragm function in patients with upper abdominal surgery.The fully engaged inspiratory muscle training increases the quality of life in patients with upper abdominal surgery.

Effect of pulmonary hypertension on exercise capacity and gas exchange in patients with chronic obstructive pulmonary disease living at high altitude

Background: Pulmonary hypertension (PH) is associated with decreased exercise tolerance in chronic obstructive pulmonary disease (COPD) patients, but in the altitude the response to exercise in those patients is unknown. Our objective was to compare exercise capacity, gas exchange and ventilatory alterations between COPD patients with PH (COPD-PH) and without PH (COPD-nonPH) residents at high altitude (2640 m). Methods: One hundred thirty-two COPD-nonPH, 82 COPD-PH, and 47 controls were included. Dyspnea by Borg scale, oxygen consumption (VO₂), work rate (WR), ventilatory equivalents (VE/VCO₂), dead space to tidal volume ratio (V_D/V_T), alveolar-arterial oxygen tension gradient (AaPO₂), and arterial-end-tidal carbon dioxide pressure gradient (Pa-ETCO₂) were measurement during a cardiopulmonary exercise test. For comparison of variables between groups, Kruskal-Wallis or one-way ANOVA tests were used, and stepwise regression analysis to test the association between PH and exercise capacity. Results: All COPD patients had a lower exercise capacity and higher PaCO₂, A-aPO₂ and V_D/V_T than controls. The VO₂ % predicted (61.3 ± 20.6 vs 75.3 ± 17.9; p < 0.001) and WR % predicted (65.3 ± 17.9 vs 75.3 ± 17.9; p < 0.001) were lower in COPD-PH than in COPD-nonPH. At peak exercise, dyspnea was higher in COPD-PH (p = 0.011). During exercise, in COPD-PH, the PaO₂ was lower (p < 0.001), and AaPO₂ (p < 0.001), Pa-ETCO₂ (p = 0.033), VE/VCO₂ (p = 0.019), and V_D/V_T (p = 0.007) were higher than in COPD-nonPH. In the multivariate analysis, PH was significantly associated with lower peak VO₂ and WR (p < 0.001). Conclusion: In COPD patients residing at high altitude, the presence of PH was an independent factor related to the exercise capacity. Also, in COPD-PH patients there were more dyspnea and alterations in gas exchange during the exercise than in those without PH.

Different Responses to Pulmonary Rehabilitation in COPD Patients with Different Work Efficiencies

BACKGROUND

Chronic obstructive pulmonary disease (COPD) often involves the cardiopulmonary dysfunction that deteriorates health-related quality of life (HRQL) and exercise capacity. Work efficiency (WE) indicates the efficiency of overall oxygen consumption (VO2) during exercise. This study investigated whether different WEs have different effects on pulmonary rehabilitation (PR).

METHODS

Forty-five patients with stable COPD were scheduled for PR. The PR programs consisted of twice-weekly sessions for three months. These patients were comprehensively evaluated by cardiopulmonary exercise testing and COPD assessment test (CAT) before and after PR. We compared these parameters between patients with a normal versus poor WE.

RESULTS

Twenty-one patients had a normal WE and twenty-four patients had a poor WE (<8.6 mL/min/watt). Patients with a poor WE had earlier anaerobic metabolism, a poorer oxygen pulse, lower exercise capacity, more exertional dyspnea, and a poorer HRQL than those with a normal WE. PR improved exercise capacity, HRQL, anaerobic threshold, exertional dyspnea and leg fatigue in patients with either normal or poor WE. However, significant improvement of WE, oxygen pulse, respiratory frequency (Rf) during exercise, chest tightness, activity and sleepiness by CAT were noted only in patients with a poor WE. Among the patients with a poor WE, 29% patients had WE returned to normal after PR.

CONCLUSION

Patients with different WE had different responses to PR. PR improved exercise capacity and HRQL regardless of a normal or poor WE. However, WE, oxygen pulse, Rf during exercise, chest tightness, activity and sleepiness were only improved in patients with a poor WE.

Responses to incremental exercise and the impact of the coexistence of HF and COPD on exercise capacity: a follow-up study

Our aim was to evaluate: (1) the prevalence of coexistence of heart failure (HF) and chronic obstructive pulmonary disease (COPD) in the studied patients; (2) the impact of HF + COPD on exercise performance and contrasting exercise responses in patients with only a diagnosis of HF or COPD; and (3) the relationship between clinical characteristics and measures of cardiorespiratory fitness; (4) verify the occurrence of cardiopulmonary events in the follow-up period of up to 24 months years. The current study included 124 patients (HF: 46, COPD: 53 and HF + COPD: 25) that performed advanced pulmonary function tests, echocardiography, analysis of body composition by bioimpedance and symptom-limited incremental cardiopulmonary exercise testing (CPET) on a cycle ergometer. Key CPET variables were calculated for all patients as previously described. The [Formula: see text]E/[Formula: see text]CO2 slope was obtained through linear regression analysis. Additionally, the linear relationship between oxygen uptake and the log transformation of [Formula: see text]E (OUES) was calculated using the following equation: [Formula: see text]O2 = a log [Formula: see text]E + b, with the constant 'a' referring to the rate of increase of [Formula: see text]O2. Circulatory power (CP) was obtained through the product of peak [Formula: see text]O2 and peak systolic blood pressure and Ventilatory Power (VP) was calculated by dividing peak systolic blood pressure by the [Formula: see text]E/[Formula: see text]CO2 slope. After the CPET, all patients were contacted by telephone every 6 months (6, 12, 18, 24) and questioned about exacerbations, hospitalizations for cardiopulmonary causes and death. We found a 20% prevalence of HF + COPD overlap in the studied patients. The COPD and HF + COPD groups were older (HF: 60 ± 8, COPD: 65 ± 7, HF + COPD: 68 ± 7). In relation to cardiac function, as expected, patients with COPD presented preserved ejection fraction (HF: 40 ± 7, COPD: 70 ± 8, HF + COPD: 38 ± 8) while in the HF and HF + COPD demonstrated similar levels of systolic dysfunction. The COPD and HF + COPD patients showed evidence of an obstructive ventilatory disorder confirmed by the value of %FEV1 (HF: 84 ± 20, COPD: 54 ± 21, HF + COPD: 65 ± 25). Patients with HF + COPD demonstrated a lower work rate (WR), peak oxygen uptake ([Formula: see text]O2), rate pressure product (RPP), CP and VP compared to those only diagnosed with HF and COPD. In addition, significant correlations were observed between lean mass and peak [Formula: see text]O2 (r: 0.56 p < 0.001), OUES (r: 0.42 p < 0.001), and O2 pulse (r: 0.58 p < 0.001), lung diffusing factor for carbon monoxide (DLCO) and WR (r: 0.51 p < 0.001), DLCO and VP (r: 0.40 p: 0.002), forced expiratory volume in first second (FEV1) and peak [Formula: see text]O2 (r: 0.52; p < 0.001), and FEV1 and WR (r: 0.62; p < 0.001). There were no significant differences in the occurrence of events and deaths contrasting both groups. The coexistence of HF + COPD induces greater impairment on exercise performance when compared to patients without overlapping diseases, however the overlap of the two diseases did not increase the probability of the occurrence of cardiopulmonary events and deaths when compared to groups with isolated diseases in the period studied. CPET provides important information to guide effective strategies for these patients with the goal of improving exercise performance and functional capacity. Moreover, given our findings related to pulmonary function, body composition and exercise responses, evidenced that the lean mass, FEV1 and DLCO influence important responses to exercise.

Practical guide to cardiopulmonary exercise testing in adults

Unexplained exertional dyspnoea or fatigue can arise from a number of underlying disorders and shows only a weak correlation with resting functional or imaging tests. Noninvasive cardiopulmonary exercise testing (CPET) offers a unique, but still under-utilised and unrecognised, opportunity to study cardiopulmonary and metabolic changes simultaneously. CPET can distinguish between a normal and an abnormal exercise response and usually identifies which of multiple pathophysiological conditions alone or in combination is the leading cause of exercise intolerance. Therefore, it improves diagnostic accuracy and patient health care by directing more targeted diagnostics and facilitating treatment decisions. Consequently, CPET should be one of the early tests used to assess exercise intolerance. However, this test requires specific knowledge and there is still a major information gap for those physicians primarily interested in learning how to systematically analyse and interpret CPET findings. This article describes the underlying principles of exercise physiology and provides a practical guide to performing CPET and interpreting the results in adults.

The role of inspiratory capacity and tidal flow in diagnosing exercise ventilatory limitation in Cystic Fibrosis

BACKGROUND

Exercise ventilatory limitation conventionally defined by reduced breathing reserve (BR) may underestimate the effect of lung disease on exercise capacity in patients with mild to moderate obstructive lung diseases.

OBJECTIVE

To investigate whether ventilatory limitation may be present despite a normal BR in Cystic Fibrosis (CF).

METHODS

Twenty adult CF patients (age 16-58y) with a wide range of pulmonary obstruction severity completed a symptom-limited incremental exercise test on a cycle ergometer. Operating lung volumes were derived from inspiratory capacity (IC) measurement during exercise and exercise tidal flow volume loop analysis.

RESULTS

six patients had a severe airway obstruction (FEV₁<45% predicted) and conventional evidence of ventilatory limitation (low BR). Fourteen patients had mild to moderate-severe airway obstructive (FEV₁ 46-103% predicted), and a normal BR [12-62 L/min, BR% (17-40)]. However, dynamic respiratory mechanics demonstrated that even CF patients with mild to moderate-severe lung disease had clear evidence of ventilatory limitation during exercise. IC was decreased by (median) 580 ml (range 90-1180 ml) during exercise, indicating dynamic hyperinflation. Inspiratory reserve volume at peak exercise was 445 ml (241-1350 ml) indicating mechanical constraint on the respiratory system. The exercise tidal flow met or exceeded the expiratory boundary of the maximal flow volume loop over 72% of the expiratory volume (range 40-90%), indicating expiratory flow limitation.

CONCLUSION

Reduced BR as a sole criterion underestimates ventilatory limitation during exercise in mild to moderate-severe CF patients. Assessment of dynamic respiratory mechanics during exercise revealed ventilatory limitation, present even in patients with mild obstruction.

Value of Cardiopulmonary Exercise Testing in the Prognosis Assessment of Chronic Obstructive Pulmonary Disease Patients: A Retrospective, Multicentre Cohort Study

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is one of the most common chronic diseases associated with high mortality. Previous studies suggested a prognostic role for peak oxygen uptake (VO2peak) assessed during cardiopulmonary exercise testing (CPET) in patients with COPD. However, most of these studies had small sample sizes or short follow-up periods, and despite their relevance, CPET parameters are not included in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) tool for assessment of severity.

OBJECTIVES

We therefore aimed to assess the prognostic value of CPET parameters in a large cohort of outpatients with COPD.

METHODS

In this retrospective, multicentre cohort study, medical records of patients with COPD who underwent CPET during 2004-2017 were reviewed and demographics, smoking habits, GOLD grade and category, exacerbation frequency, dyspnoea score, lung function measurements, and CPET parameters were documented. Relationships with survival were evaluated using Kaplan-Meier analysis, Cox regression, and receiver operating characteristic (ROC) curves.

RESULTS

Of a total of 347 patients, 312 patients were included. Five-year and 10-year survival probability was 75% and 57%, respectively. VO2peak significantly predicted survival (hazard ratio: 0.886 [95% confidence interval: 0.830; 0.946]). The optimal VO2peak threshold for discrimination of 5-year survival was 14.6 mL/kg/min (area under ROC curve: 0.713). Five-year survival in patients with VO2peak <14.6 mL/kg/min versus ≥ 14.6 mL/kg/min was 60% versus 86% in GOLD categories A/B and 64% versus 90% in GOLD categories C/D.

CONCLUSIONS

We confirm that VO2peak is a highly significant predictor of survival in COPD patients and recommend the incorporation of VO2peak into the assessment of COPD severity.

Exercise-Based Rehabilitation Delivery Models in Comorbid Chronic Pulmonary Disease and Chronic Heart Failure

Among the most prevalent multimorbidities that accompany the aging process, chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF) stand out, representing the main causes of hospital admissions in the world. The prevalence of COPD coexistence in patients with CHF is higher than in control subjects, given the common risk factors associated with a complex process of chronic diseases developing in the aging process. COPD-CHF coexistence confers a marked negative impact on mechanical-ventilatory, cardiocirculatory, autonomic, gas exchange, muscular, ventilatory, and cerebral blood flow, further impairing the reduced exercise capacity and health status of either condition alone. In this context, integrated approach to the cardiopulmonary based on pharmacological optimization and non-pharmacological treatment (i.e., exercise-based cardiopulmonary and metabolic rehabilitation) can be emphatically encouraged by health professionals as they are safe and well-tolerated, reducing hospital readmissions, morbidity, and mortality. This review aims to explore aerobic exercise, the cornerstone of cardiopulmonary and metabolic rehabilitation, resistance and inspiratory muscle training and exercise-based rehabilitation delivery models in patients with COPD-CHF multimorbidities across the continuum of the disease. In addition, the review address the importance of adjuncts to enhance exercise capacity in these patients, which may be used to optimize the gains obtained in these programs.

Exertional ventilation/carbon dioxide output relationship in COPD: from physiological mechanisms to clinical applications

There is well established evidence that the minute ventilation (V′_E)/carbon dioxide output (V′_CO2) relationship is relevant to a number of patient-related outcomes in COPD. In most circumstances, an increased V′_E/V′_CO2 reflects an enlarged physiological dead space (“wasted” ventilation), although alveolar hyperventilation (largely due to increased chemosensitivity) may play an adjunct role, particularly in patients with coexistent cardiovascular disease. The V′_E/V′_CO2 nadir, in particular, has been found to be an important predictor of dyspnoea and poor exercise tolerance, even in patients with largely preserved forced expiratory volume in 1 s. As the disease progresses, a high nadir might help to unravel the cause of disproportionate breathlessness. When analysed in association with measurements of dynamic inspiratory constraints, a high V′_E/V′_CO2 is valuable to ascertain a role for the “lungs” in limiting dyspnoeic patients. Regardless of disease severity, cardiocirculatory (heart failure and pulmonary hypertension) and respiratory (lung fibrosis) comorbidities can further increase V′_E/V′_CO2. A high V′_E/V′_CO2 is a predictor of poor outcome in lung resection surgery, adding value to resting lung hyperinflation in predicting all-cause and respiratory mortality across the spectrum of disease severity. Considering its potential usefulness, the V′_E/V′_CO2 should be valued in the clinical management of patients with COPD.

The minute ventilation/carbon dioxide production relationship is relevant to a number of patient-related outcomes in COPD. Minute ventilation/carbon dioxide production, therefore, should be valued in the clinical management of these patients.https://bit.ly/3df2upH

Exercise Capacity, Ventilatory Response, and Gas Exchange in COPD Patients With Mild to Severe Obstruction Residing at High Altitude

Background

Exercise intolerance, desaturation, and dyspnea are common features in patients with chronic obstructive pulmonary disease (COPD). At altitude, the barometric pressure (BP) decreases, and therefore the inspired oxygen pressure and the partial pressure of arterial oxygen (PaO₂) also decrease in healthy subjects and even more in patients with COPD. Most of the studies evaluating ventilation and arterial blood gas (ABG) during exercise in COPD patients have been conducted at sea level and in small populations of people ascending to high altitudes. Our objective was to compare exercise capacity, gas exchange, ventilatory alterations, and symptoms in COPD patients at the altitude of Bogotá (2,640 m), of all degrees of severity.

Methods

Measurement during a cardiopulmonary exercise test of oxygen consumption (VO₂), minute ventilation (VE), tidal volume (VT), heart rate (HR), ventilatory equivalents of CO₂ (VE/VCO₂), inspiratory capacity (IC), end-tidal carbon dioxide tension (PETCO₂), and ABG. For the comparison of the variables between the control subjects and the patients according to the GOLD stages, the non-parametric Kruskal–Wallis test or the one-way analysis of variance test was used.

Results

Eighty-one controls and 525 patients with COPD aged 67.5 ± 9.1 years were included. Compared with controls, COPD patients had lower VO₂ and VE (p < 0.001) and higher VE/VCO₂ (p = 0.001), A-aPO₂, and V_D/V_T (p < 0.001). In COPD patients, PaO₂ and saturation decreased, and delta IC (p = 0.004) and VT/IC increased (p = 0.002). These alterations were also seen in mild COPD and progressed with increasing severity of the obstruction.

Conclusion

The main findings of this study in COPD patients residing at high altitude were a progressive decrease in exercise capacity, increased dyspnea, dynamic hyperinflation, restrictive mechanical constraints, and gas exchange abnormalities during exercise, across GOLD stages 1–4. In patients with mild COPD, there were also lower exercise capacity and gas exchange alterations, with significant differences from controls. Compared with studies at sea level, because of the lower inspired oxygen pressure and the compensatory increase in ventilation, hypoxemia at rest and during exercise was more severe; PaCO₂ and PETCO₂ were lower; and VE/VO₂ was higher.

Clinical Characteristics of COPD Patients According to COPD Assessment Test (CAT) Score Level: Cross-Sectional Study

PURPOSE

The chronic obstructive pulmonary disease (COPD) assessment test (CAT) is widely used to assess the impact of COPD symptoms on health status. Whilst the CAT consists of eight different items, details on the distribution of each item are limited. This study aimed to investigate the distribution and clinical implication of each CAT item, stratified by CAT severity group, in stable COPD patients.

PATIENTS AND METHODS

This was a cross-sectional study at a single referral hospital in South Korea. Spirometry confirmed COPD patients with CAT measured at the first clinical visit were retrospectively identified. Patients were categorized into three groups: low (0 ≤ CAT < 10), medium (10 ≤ CAT < 20), and high (20 ≤ CAT ≤ 40) impact group. For the purpose of this analysis, the first four items (cough, sputum, chest tightness, and dyspnea) and the remaining four items (activities, confidence, sleep and energy) were also grouped as "pulmonary" and "extra-pulmonary", respectively.

RESULTS

A total of 815 patients were included, and mean (SD) forced expiratory volume in 1 s (FEV1) was 62.8 (17.4) % pred. Among them, 300 patients (36.8%) were in the high impact group and had a greater exacerbation history and lower lung function. The proportion of "extra-pulmonary" items score was greater in patients with higher total CAT scores, with the activity and confidence items showing higher scores.

CONCLUSION

In our study, in addition to dyspnea, activity limitation is a particular problem in individual patients with higher CAT total scores, for which physicians need to pay more attention. Our study suggests that whilst CAT total score captures the overall impact of COPD, each item of the CAT contains potentially useful information in understanding the patient's symptom burden.

Chronic obstructive pulmonary disease and atrial fibrillation: an interdisciplinary perspective

Chronic obstructive pulmonary disease (COPD) is highly prevalent among patients with atrial fibrillation (AF), shares common risk factors, and adds to the overall morbidity and mortality in this population. Additionally, it may promote AF and impair treatment efficacy. The prevalence of COPD in AF patients is high and is estimated to be ∼25%. Diagnosis and treatment of COPD in AF patients requires a close interdisciplinary collaboration between the electrophysiologist/cardiologist and pulmonologist. Differential diagnosis may be challenging, especially in elderly and smoking patients complaining of unspecific symptoms such as dyspnoea and fatigue. Routine evaluation of lung function and determination of natriuretic peptides and echocardiography may be reasonable to detect COPD and heart failure as contributing causes of dyspnoea. Acute exacerbation of COPD transiently increases AF risk due to hypoxia-mediated mechanisms, inflammation, increased use of beta-2 agonists, and autonomic changes. Observational data suggest that COPD promotes AF progression, increases AF recurrence after cardioversion, and reduces the efficacy of catheter-based antiarrhythmic therapy. However, it remains unclear whether treatment of COPD improves AF outcomes and which metric should be used to determine COPD severity and guide treatment in AF patients. Data from non-randomized studies suggest that COPD is associated with increased AF recurrence after electrical cardioversion and catheter ablation. Future prospective cohort studies in AF patients are needed to confirm the relationship between COPD and AF, the benefits of treatment of either COPD or AF in this population, and to clarify the need and cost-effectiveness of routine COPD screening.

Pulmonary function testing in COPD: looking beyond the curtain of FEV1

Chronic obstructive pulmonary disease (COPD) management remains challenging due to the high heterogeneity of clinical symptoms and the complex pathophysiological basis of the disease. Airflow limitation, diagnosed by spirometry, remains the cornerstone of the diagnosis. However, the calculation of the forced expiratory volume in the first second (FEV1) alone, has limitations in uncovering the underlying complexity of the disease. Incorporating additional pulmonary function tests (PFTs) in the everyday clinical evaluation of COPD patients, like resting volume, capacity and airway resistance measurements, diffusion capacity measurements, forced oscillation technique, field and cardiopulmonary exercise testing and muscle strength evaluation, may prove essential in tailoring medical management to meet the needs of such a heterogeneous patient population. We aimed to provide a comprehensive overview of the available PFTs, which can be incorporated into the primary care physician's practice to enhance the efficiency of COPD management.

The effect of long-acting dual bronchodilator therapy on exercise tolerance, dynamic hyperinflation, and dead space during constant work rate exercise in COPD

We investigated whether dual bronchodilator therapy (glycopyrrolate/formoterol fumarate; GFF; Bevespi Aerosphere) would increase exercise tolerance during a high-intensity constant work rate exercise test (CWRET) and the relative contributions of dead space ventilation (V_D/V_T) and dynamic hyperinflation (change in inspiratory capacity) to exercise limitation in chronic obstructive pulmonary disease (COPD). In all, 48 patients with COPD (62.9 ± 7.6 yrs; 33 male; GOLD spirometry stage 1/2/3/4, n = 2/35/11/0) performed a randomized, double blind, placebo (PL) controlled, two-period crossover, single-center trial. Gas exchange and inspiratory capacity (IC) were assessed during cycle ergometry at 80% incremental exercise peak work rate. Transcutaneous [Formula: see text] (Tc[Formula: see text]) measurement was used for V_D/V_T estimation. Baseline postalbuterol forced expiratory volume in 1 s (FEV₁) was 1.86 ± 0.58 L (63.6% ± 13.9 predicted). GFF increased FEV₁ by 0.18 ± 0.21 L relative to placebo (PL; P < 0.001). CWRET endurance time was greater after GFF vs. PL (383 ± 184 s vs. 328 ± 115 s; difference 55 ± 125 s; P = 0.013; confidence interval: 20-90 s), a 17% increase. IC on GFF was above placebo IC at all time points and fell less with GFF vs. PL (P ≤ 0.0001). Isotime tidal volume (1.54 ± 0.50 vs. 1.47 ± 0.45 L; P = 0.022) and ventilation (52.9 ± 19.9 vs. 51.0 ± 18.9 L/min; P = 0.011) were greater, and respiratory rate was unchanged (34.9 ± 9.2 vs. 35.1 ± 8.0 br/min, P = 0.865). Isotime V_D/V_T did not differ between groups (GFF 0.28 ± 0.08 vs. PL 0.27 ± 0.09; P = 0.926). GFF increased exercise tolerance in patients with COPD, and the increase was accompanied by attenuated dynamic hyperinflation without altering V_D/V_T.NEW & NOTEWORTHY This study was a randomized clinical trial (NCT03081156) that collected detailed physiology data to investigate the effect of dual bronchodilator therapy on exercise tolerance in COPD, and additionally to determine the relative contributions of changes in dead space ventilation (V_D/V_T) and dynamic hyperinflation to alterations in exercise limitation. We utilized a unique noninvasive method to assess V_D/V_T (transcutaneous carbon dioxide, Tc[Formula: see text]) and found that dual bronchodilators yielded a moderate improvement in exercise tolerance. Importantly, attenuation of dynamic hyperinflation rather than change in dead space ventilation was the most important contributor to exercise tolerance improvement.

Recent Advances in the Physiological Assessment of Dyspneic Patients with Mild COPD

There is growing recognition that a sizable fraction of COPD patients with forced expiratory volume in one second (FEV₁)/forced vital capacity ratio below the lower limit of normal but preserved FEV₁ reports out-of-proportion dyspnea relative to the severity of airflow limitation. Most physicians, however, assume that patients' breathlessness is unlikely to reflect the negative physiological consequences of COPD vis-à-vis FEV₁ normalcy. This concise review integrates the findings of recent studies which uncovered the key pathophysiological features shared by these patients: poor pulmonary gas exchange efficiency (increased "wasted" ventilation) and gas trapping. These abnormalities are associated with two well-known causes of exertional dyspnea: heightened ventilation relative to metabolic demand and critically low inspiratory reserves, respectively. From a clinical standpoint, a low diffusion capacity associated with increased residual volume (RV) and/or RV/total lung capacity ratio might uncover these disturbances, identifying the subset of patients in whom exertional dyspnea is causally related to "mild" COPD.

Poor Work Efficiency is Associated with Poor Exercise Capacity and Health-Related Quality of Life in Patients with Chronic Obstructive Pulmonary Disease

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is a progressive disease with deteriorating cardiopulmonary function that decreases the health-related quality of life (HRQL) and exercise capacity. Patients with COPD often have cardiovascular and muscular problems that hinder oxygen uptake by peripheral tissues, resulting in poor oxygen consumption efficiency. It is important to develop new physiological parameters to evaluate oxygen consumption efficiency during activities and to evaluate its association with exercise capacity and HRQL. Work efficiency (WE) measures oxygen consumption efficiency during exercise. We hypothesize that patients with poor WE should have exercise intolerance and poor HRQL. Therefore, we aimed to evaluate the association between WE and exercise capacity, HRQL and other cardiopulmonary parameters.

PATIENTS AND METHODS

Seventy-eight patients with COPD were evaluated with spirometry, cardiopulmonary exercise testing, and assessment of dyspnea score and HRQL (using the St. George's Respiratory Questionnaire [SGRQ]). Cardiopulmonary exercise testing was performed using a cycle ergometer with an incremental protocol and exhaled breath analysis to assess oxygen consumption. WE was defined as the relationship between oxygen consumption and workload.

RESULTS

There were 31 patients with normal WE (group I) and 47 patients (group II) with poor WE. Patients with poor WE had lower exercise capacity (maximal oxygen consumption, group I vs II as 1050±53 vs 845 ±34 mL/min, p=0.0011), poorer HRQL (SGRQ score 41.1±3.0 vs 55±2.2, p=0.0002), higher exertional dyspnea score (5.1±0.2 vs 6.1±0.2, p= 0.0034) and early anaerobic metabolism during exercise (anaerobic threshold, 672±27 vs 583 ±18 mL/min, p=0.0052).

CONCLUSION

WE is associated with exercise capacity and HRQL. Here, patients with poor WE also had exercise intolerance, poorer HRQL, and more exertional dyspnea.

Transcutaneous PCO2 for Exercise Gas Exchange Efficiency in Chronic Obstructive Pulmonary Disease

Gas exchange inefficiency and dynamic hyperinflation contributes to exercise limitation in chronic obstructive pulmonary disease (COPD). It is also characterized by an elevated fraction of physiological dead space (V_D/V_T). Noninvasive methods for accurate V_D/V_T assessment during exercise in patients are lacking. The current study sought to compare transcutaneous PCO₂ (TcPCO₂) with the gold standard-arterial PCO₂ (PaCO₂)-and other available methods (end tidal CO₂ and the Jones equation) for estimating V_D/V_T during incremental exercise in COPD. Ten COPD patients completed a symptom limited incremental cycle exercise. TcPCO₂ was measured by a heated electrode on the ear-lobe. Radial artery blood was collected at rest, during unloaded cycling (UL) and every minute during exercise and recovery. Ventilation and gas exchange were measured breath-by-breath. Bland-Altman analysis examined agreement of PCO₂ and V_D/V_T calculated using PaCO₂, TcPCO₂, end-tidal PCO₂ (P_ETCO₂) and estimated PaCO₂ by the Jones equation (PaCO₂-Jones). Lin's Concordance Correlation Coefficient (CCC) was assessed. 114 measurements were obtained from the 10 COPD subjects. The bias between TcPCO₂ and PaCO₂ was 0.86 mmHg with upper and lower limit of agreement ranging -2.28 mmHg to 3.99 mmHg. Correlation between TcPCO₂ and PaCO₂ during rest and exercise was r²=0.907 (p < 0.001; CCC = 0.941) and V_D/V_T using TcPCO₂ vs. PaCO₂ was r²=0.958 (p < 0.0001; CCC = 0.967). Correlation between PaCO₂-Jones and P_ETCO₂ vs. PaCO₂ were r²=0.755, 0.755, (p < 0.001; CCC = 0.832, 0.718) and for V_D/V_T calculation (r²=0.793, 0.610; p < 0.0001; CCC = 0.760, 0.448), respectively. The results support the accuracy of TcPCO₂ to reflect PaCO₂ and calculate V_D/V_T during rest and exercise, but not in recovery, in COPD patients, enabling improved accuracy of noninvasive assessment of gas exchange inefficiency during incremental exercise testing.

Ventilatory constraint is more severe in walking than cycling in patients with COPD

Due to its effectivity in assessing functional capacity and adding prognostic information to the staging of chronic obstructive pulmonary disease (COPD) patients, the 6-min walk test (6MWT) is extensively used in clinical evaluation. Currently, there is little information about the physiological response this test elicits in patients, especially when compared to cardiopulmonary exercise test (CPET). The aim of the study was to compare ventilatory and metabolic responses between these tests commonly used for the assessment of clinical outcome. A group of 20 patients with moderate to very severe COPD were tested for their pulmonary function (flow-volume curve, static lung volumes), occlusion mouth pressures and breath-by-breath measurement of flow, volumes, and oxygen (O₂) and carbon dioxide (CO₂) concentration during the 6MWT and CPET. All parameters measured during both exercise tests were assessed over the throughout of the tests and compared between each other at specified time points. Serially measured inspiratory vital capacity (IVC) decreased more rapidly and extensively during the walk-test (p ​< ​0,0001). This was accompanied by a limited increase in tidal volume (V_T) and minute ventilation (V_E), which were significantly lower in the course of the 6MWT (p ​= ​0,0003 and p ​= ​0,0097, respectively). We also noticed a significant decrease in hemoglobin oxygen saturation (SpO₂) during the 6MWT which was correlated to percent decrease in IVC (p ​= ​0,0206). Over the course of the 6MWT, oxygen consumption (VO₂) and V_T reached plateau within 2 ​min, while carbon dioxide production (VCO₂) and V_E within 3 ​min. During CPET, VO₂, VCO₂ and V_E rose continuously, while V_T reached plateau within 4 ​min. The 6MWT seems to be a rather endurance-based test associated with more pronounced dynamic lung hyperinflation and mechanical constraint of ventilation in comparison to cycling.

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Various types of exercise are tolerated differently.

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The 6MWT is, as opposed to ergometry, accompanied by a quicker increase in dynamic lung hyperinflation and desaturation.

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It seems that pedaling, as compared to walking, is the superior way of training movement for rehabilitation purposes.

Lung Function Testing in Chronic Obstructive Pulmonary Disease

Lung function testing has undisputed value in the comprehensive assessment and individualized management of chronic obstructive pulmonary disease, a pathologic condition in which a functional abnormality, poorly reversible expiratory airway obstruction, is at the core of its definition. After an overview of the physiologic underpinnings of the disease, the authors outline the role of lung function testing in this disease, including diagnosis, assessment of severity, and indication for and responses to pharmacologic and nonpharmacologic interventions. They discuss the current controversies surrounding test interpretation with these purposes in mind and provide balanced recommendations to optimize their usefulness in different clinical scenarios.

Evaluating the Benefits of Exercise Training in HFrEF or COPD Patients: ISO-LEVEL COMPARISON CAN ADD VALUABLE INFORMATION TO V˙o2peak

BACKGROUND

Heart failure with reduced ejection fraction (HFrEF) and chronic obstructive pulmonary disease (COPD) are relatively common conditions with similar symptoms of exercise intolerance and dyspnea. The aim of this study was to compare exercise capacity, ventilatory response, and breathing pattern in patient groups with either advanced HFrEF or COPD before and after exercise training.

METHODS

An observational study was conducted with parallel groups of 25 HFrEF and 25 COPD patients who took part in 6 wk of inpatient rehabilitation with exercise training. All patients underwent cardiopulmonary exercise tests at the start and end of the training, with resting arterial blood gas measurements.

RESULTS

The average peak oxygen uptake (V˙o2) was low at the start of the study but increased significantly after training in both groups, or by 2.2 ± 2.1 mL/kg/min in HFrEF patients and 1.2 ± 2.2 mL/kg/min in COPD patients. At ISO-V˙o2 (ie, same level of V˙o2 in pre- and post-exercise tests), carbon dioxide production (V˙co2) decreased after exercise training in both groups. Similarly, at ISO-V˙E (ie, same level of ventilation), breathing frequency (f) decreased and tidal volume (VT) increased, resulting in an improved breathing pattern (lower f/VT ratio) after training.

CONCLUSION

The findings of this study show that exercise training in severely affected patient groups with HFrEF or COPD led to an increase in maximal exercise capacity, a more favorable breathing pattern, and a diminished V˙co2 during exercise. Therefore, comparisons of V˙co2 and breathing pattern at ISO-levels of V˙o2 or V˙E before and after training are valuable and underutilized outcome measures in treatment studies.

Multidimensional breathlessness assessment during cardiopulmonary exercise testing in healthy adults

PURPOSE

This study explored if healthy adults could discriminate between different breathlessness dimensions when rated immediately one after another (successively) during symptom-limited incremental cardiopulmonary cycle exercise testing (CPET) using multiple single-item rating scales.

METHODS

Fifteen apparently healthy adults (60% male) aged 22 ± 2 years performed six incremental cycle CPETs separated by ≥ 48 h. During each CPET (at rest, every 2-min and at end exercise), participants rated different breathlessness sensations using the 0-10 modified Borg scale using one of six assessment protocols, randomized for order: (1) 'BREATHLESS_ALL' = breathlessness sensory intensity (SI), breathlessness unpleasantness (UN), work/effort of breathing (SQ_W/E), and unsatisfied inspiration (SQ_UI) assessed; (2) SI and UN assessed; and (3-6) SI, UN, SQ_W/E, and SQ_UI each assessed alone. Physiological responses to CPET were also evaluated.

RESULTS

Physiological and breathlessness responses to CPET were comparable across the six protocols, with the exception of SI rated lower at the highest submaximal power output (220 ± 56 watts) during the BREATHLESS_ALL protocol (0-10 Borg units 4.2 ± 1.7) compared to SI + UN (5.2 ± 2.1, p = 0.03) and SI alone (5.1 ± 1.9, p = 0.04) protocols. Ratings of SI and SQ_W/E were not significantly different when assessed in the same protocol, and were significantly higher than UN and SQ_UI, which were comparable.

CONCLUSION

In healthy younger adults, use of two separate single-item rating scales to assess breathlessness during CPET is feasible and enables the distinct sensory intensity and affective dimensions of exertional breathlessness to be assessed.

Why treatment efficacy on breathlessness in laboratory but not daily life trials? The importance of standardized exertion

PURPOSE OF REVIEW

Treatments for chronic breathlessness, including opioids and oxygen, have shown efficacy in the controlled laboratory setting, whereas effects have been inconsistent or absent in trials in daily life. This review discusses the lack of standardized exertion as a potential cause of false negative findings for breathlessness in daily life.

RECENT FINDINGS

The level of breathlessness can be modified by patients by changing their level of physical activity. Effects of opioids and oxygen have been shown at standardized level of exertion (iso-time) but not at the end of symptom-limited (peak) exertion. Trials in daily life reporting no effects on breathlessness did not standardize the exertion or employed insensitive methods, such as the 6-min walk test that should not be used for measuring breathlessness. Novel tests - the 3-min walk and stepping tests have been validated in chronic obstructive pulmonary disease and are responsive for measuring change in breathlessness.

SUMMARY

Breathlessness should be measured at standardized exertion, otherwise treatment effects may be biased or overlooked. Tests for valid measurement of breathlessness in clinical practice and daily life are available and emerging.

Managing COPD with expiratory or inspiratory pressure load training based on a prolonged expiration pattern

Background

Exertional prolonged expiration should be identified as a therapeutic target in COPD. The efficacy of expiratory or inspiratory pressure load training (EPT/IPT) based on the degree of prolonged expiration was investigated.

Methods

A total of 21 patients with COPD were divided into two groups according to the exertional change in the inspiratory duty cycle (T_I/Ttot). For 12 weeks, patients whose exertional T_I/Ttot decreased received EPT (EPT group, n=11, mean percentage forced expiratory volume in 1 s (%FEV₁), 32.8%) and those whose exertional T_I/Ttot increased received IPT (IPT group, n=10, mean %FEV₁, 45.1%).

Results

The therapeutic responses were as follows. In both groups, endurance time (EPT, +5.7 min, p<0.0001; IPT, +6.1 min, p=0.0004) on the constant work rate exercise test (WRET) and peak oxygen uptake increased (EPT, p=0.0028; IPT, p=0.0072). In the EPT group the following occurred: 1) soon after commencement of exercise with the constant WRET, the expiratory tidal volume (V_Tex) increased, reducing dyspnoea; 2) V_Tex and mean expiratory flow increased and then prolonged expiration (p=0.0001) improved at peak exercise with the incremental exercise test (ET); and 3) St. George's Respiratory Questionnaire total, activity and impact scores were improved. In the IPT group, on both the constant WRET and incremental ET, breathing frequency increased, which led to greater exercise performance with effort dyspnoea.

Conclusions

This study showed the benefits of EPT/IPT on exercise performance. If the choice of managing COPD with EPT/IPT is appropriate, inexpensive EPT/IPT may become widespread as home-based training.

Expiratory or inspiratory pressure load training (EPT/IPT) based on the degree of prolonged expiration improves exercise performance in COPD patients. If managing COPD with EPT/IPT is chosen appropriately, it could become widespread as home-based training.https://bit.ly/2ZWutWq

Heart, lungs, and muscle interplay in worsening activity-related breathlessness in advanced cardiopulmonary disease

PURPOSE OF REVIEW

Activity-related breathlessness is a key determinant of poor quality of life in patients with advanced cardiorespiratory disease. Accordingly, palliative care has assumed a prominent role in their care. The severity of breathlessness depends on a complex combination of negative cardiopulmonary interactions and increased afferent stimulation from systemic sources. We review recent data exposing the seeds and consequences of these abnormalities in combined heart failure and chronic obstructive pulmonary disease (COPD).

RECENT FINDINGS

The drive to breathe increases ('excessive breathing') secondary to an enlarged dead space and hypoxemia (largely COPD-related) and heightened afferent stimuli, for example, sympathetic overexcitation, muscle ergorreceptor activation, and anaerobic metabolism (largely heart failure-related). Increased ventilatory drive might not be fully translated into the expected lung-chest wall displacement because of the mechanical derangements brought by COPD ('inappropriate breathing'). The latter abnormalities, in turn, negatively affect the central hemodynamics which are already compromised by heart failure. Physical activity then decreases, worsening muscle atrophy and dysfunction.

SUMMARY

Beyond the imperative of optimal pharmacological treatment of each disease, strategies to lessen ventilation (e.g., walking aids, oxygen, opiates and anxiolytics, and cardiopulmonary rehabilitation) and improve mechanics (heliox, noninvasive ventilation, and inspiratory muscle training) might mitigate the burden of this devastating symptom in advanced heart failure-COPD.

Normative Peak Cardiopulmonary Exercise Test Responses in Canadian Adults Aged ≥40 Years

BACKGROUND

Up-to-date normative reference sets for cardiopulmonary exercise testing (CPET) are important to aid in the accurate interpretation of CPET in clinical or research settings.

RESEARCH QUESTION

This study aimed to (1) develop and externally validate a contemporary reference set for peak CPET responses in Canadian adults identified with population-based sampling; and (2) evaluate previously recommended reference equations for predicting peak CPET responses.

STUDY DESIGN AND METHODS

Participants were healthy adults who were ≥40 years old from the Canadian Cohort Obstructive Lung Disease who completed an incremental cycle CPET. Prediction models for peak CPET responses were estimated from readily available participant characteristics (age, sex, height, body mass) with the use of quantile regression. External validation was performed with a second convenience sample of healthy adults. Peak CPET parameters that were measured and predicted in the validation cohort were assessed for equivalence (two one-sided tests of equivalence for paired-samples and level of agreement (Bland-Altman analyses). Two one-sided tests of equivalence for paired samples assessed differences between responses in the derivation cohort using previously recommended reference equations.

RESULTS

Normative reference ranges (5th-95th percentiles) for 28 peak CPET parameters and prediction models for 8 peak CPET parameters were based on 173 participants (47% male) who were 64 ± 10 years old. In the validation cohort (n = 84), peak CPET responses that were predicted with the newly generated models were equivalent to the measured values. Peak cardiac parameters predicted by the previously recommended reference equations by Jones and colleagues and Hansen and colleagues were significantly higher.

INTERPRETATION

This study provides reference ranges and prediction models for peak cardiac, ventilatory, operating lung volume, gas exchange, and symptom responses to incremental CPET and presents the most comprehensive reference set to date in Canadian adults who were ≥40 years old to be identified with population-based sampling.

Evaluation of Exertional Ventilatory Parameters Using Oscillometry in COPD

Background

Oscillometry is a tool to measure respiratory impedance that requires minimal patients’ effort. In patients with chronic obstructive pulmonary disease (COPD), the correlation of respiratory impedance at rest with exertional ventilatory parameters, including exercise tolerance, has scarcely been reported. In addition, the utility of oscillometric parameters might differ between the inspiratory and expiratory phases due to airflow obstruction during expiration, but the hypothesis had not been validated. The aim of the present study was to investigate whether oscillometric parameters are associated with exertional ventilatory parameters in patients with COPD.

Methods

Fifty-five subjects with COPD who attended clinics at the National Hospital Organization Osaka Toneyama Medical Center performed spirometry, oscillometry, and cardiopulmonary exercise testing (CPET) within 2 weeks. The correlations between parameters of spirometry, oscillometry, and CPET were analyzed using Spearman’s rank correlation coefficient, univariate, and multivariate analyses.

Results

Respiratory reactance had better correlations with the CPET parameters than respiratory resistance. Moreover, inspiratory reactance at rest correlated with the CPET parameters stronger than expiratory reactance. In particular, inspiratory resonant frequency (Fres-ins) correlated with peak oxygen uptake (r_S=−0.549, p<0.01) and dead space to tidal volume ratio at peak exercise (r_S=0.677, p<0.01) and the best predicted expiratory tidal volume (V_T ex) at peak exercise of all the oscillometric parameters (r_S=−0.679, p<0.01). However, the correlation between Fres-ins and V_T ex at peak exercise became weak in subjects with severe and very severe COPD during exercise.

Conclusion

Measurement of respiratory reactance is useful for the effortless evaluation of not only exertional ventilatory parameters but exercise tolerance in patients with COPD. The correlation of respiratory impedance with exertional ventilatory parameters can become weak in patients with advanced COPD; thus, the measurement of oscillometry might not be appropriate for evaluating exertional ventilatory parameters of patients with advanced COPD.

Are the “critical” inspiratory constraints actually decisive to limit exercise tolerance in COPD?

Exercise intolerance is characteristically multi-factorial in patients with chronic obstructive pulmonary disease (COPD) [1]. At least in symptomatic patients with moderate-to-severe airflow limitation, higher operating lung volumes assume a relevant role in decreasing patients’ tolerance to sustain “prolonged” exercise. As a consequence of the dynamic increase in the end-expiratory lung volume, tidal volume (VT) occurs close to total lung capacity (TLC), thereby reducing the room for further lung–chest wall expansion. The combination of low dynamic lung compliance and a severely reduced inspiratory reserve volume causes a mismatch between a growing respiratory neural drive and the resulting lung–chest wall displacement [2]. It has been postulated that such critical inspiratory constraints (CIC) lead to a plateau in VT, and a concomitant increase in dyspnoea as a function of ventilation (V′_E) [3]. Accordingly, patients change their perception of the uncomfortable respiratory sensations from “laboured breathing” to “insufficient inspiration”, prompting early exercise termination [4].

The concept of critical inspiratory constraints is key to the modern understanding of exercise pathophysiology in patients with moderate-to-severe COPDhttps://bit.ly/2A6bCxD

Mechanisms of Exercise Limitation and Prevalence of Pulmonary Hypertension in Pulmonary Langerhans Cell Histiocytosis

BACKGROUND

Pulmonary Langerhans cell histiocytosis (PLCH) determines reduced exercise capacity. The speculated mechanisms of exercise impairment in PLCH are ventilatory and cardiocirculatory limitations, including pulmonary hypertension (PH).

RESEARCH QUESTION

What are the mechanisms of exercise limitation, the exercise capacity, and the prevalence of dynamic hyperinflation (DH) and PH in PLCH?

STUDY DESIGN AND METHODS

In a cross-sectional study, patients with PLCH underwent an incremental treadmill cardiopulmonary exercise test with an evaluation of DH, pulmonary function tests, and transthoracic echocardiography. Those patients with lung diffusing capacity for carbon monoxide (Dlco) < 40% predicted and/or transthoracic echocardiogram with tricuspid regurgitation velocity > 2.5 m/s and/or with indirect PH signs underwent right heart catheterization.

RESULTS

Thirty-five patients were included (68% women; mean age, 47 ± 11 years). Ventilatory and cardiocirculatory limitations, impairment suggestive of PH, and impaired gas exchange occurred in 88%, 67%, 29%, and 88% of patients, respectively. The limitation was multifactorial in 71%, exercise capacity was reduced in 71%, and DH occurred in 68% of patients. FEV₁ and Dlco were 64 ± 22% predicted and 56 ± 21% predicted. Reduction in Dlco, an obstructive pattern, and air trapping occurred in 80%, 77%, and 37% of patients. FEV₁ and Dlco were good predictors of exercise capacity. The prevalence of PH was 41%, predominantly with a precapillary pattern, and mean pulmonary artery pressure correlated best with FEV₁ and tricuspid regurgitation velocity.

INTERPRETATION

PH is frequent and exercise impairment is common and multifactorial in PLCH. The most prevalent mechanisms are ventilatory, cardiocirculatory, and suggestive of PH limitations.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; No.: NCT02665546; URL: www.clinicaltrials.gov.

Day and Night Control of COPD and Role of Pharmacotherapy: A Review

The topic of 24-hour management of COPD is related to day-to-night symptoms management, specific follow-up and patients' adherence to therapy. COPD symptoms strongly vary during day and night, being worse in the night and early morning. This variability is not always adequately considered in the trials. Night-time symptoms are predictive of higher mortality and more frequent exacerbations; therefore, they should be a target of therapy. During night-time, in COPD patients the supine position is responsible for a different thoracic physiology; moreover, during some sleep phases the vagal stimulation determines increased bronchial secretions, increased blood flow in the bronchial circulation (enhancing inflammation) and increased airway resistance (broncho-motor tone). Moreover, in COPD patients the circadian rhythm may be impaired. The role of pharmacotherapy in this regard is still poorly investigated. Symptoms can be grossly differentiated according to the different phenotypes of the disease: wheezing recalls asthma, while dyspnea is strongly related to emphysema (dynamic hyperinflation) or obstructive bronchiolitis (secretions). Those symptoms may be different targets of therapy. In this regard, GOLD recommendations for the first time introduced the concept of phenotype distinction suggesting the use of inhaled corticosteroids (ICS) particularly when an asthmatic pattern or eosiophilic inflammations are present, and hypothesized different approaches to target symptoms (ie, dyspnea) or exacerbations. Pharmacotherapy should be evaluated and possibly directed on the basis of circadian variations, for instance, supporting the use of twice-daily rapid-action bronchodilators and evening dose of ICS. Recommendations on day and night symptoms monitoring strategies and choice of the specific drug according to patient's profile are still not systematically investigated or established. This review is the summary of an advisory board on the topic "24-hour control of COPD and role of pharmacotherapy", held by five pulmonologists, experts in respiratory pathophysiology, pharmacology and sleep medicine.

Cardiopulmonary exercise testing in patients with asthma: What is its clinical value?

Asthma is one of the most common respiratory disorders, characterized by fully or largely reversible airflow limitation. Asthma symptoms can be triggered or magnified during exertion, while physical activity limitation is often present among asthmatic patients. Cardiopulmonary exercise testing (CPET) is a dynamic, non-invasive technique which provides a thorough assessment of exercise physiology, involving the integrative assessment of cardiopulmonary, neuromuscular and metabolic responses during exercise. This review summarizes current evidence regarding the utility of CPET in the diagnostic work-up, functional evaluation and therapeutic intervention among patients with asthma, highlighting its potential role for thorough patient assessment and physician clinical desicion-making.

Cardiopulmonary exercise testing in chronic obstructive pulmonary disease: An update on its clinical value and applications

Chronic obstructive pulmonary disease is a debilitating disorder, characterized by airflow limitation, exercise impairment, reduced functional capacity and significant systemic comorbidity, which complicates the course of the disease. The critical inspiratory constraint to tidal volume expansion during exercise (that may be further complicated by the presence of dynamic hyperinflation), abnormalities in oxygen transportation and gas exchange abnormalities are the major pathophysiological mechanisms of exercise intolerance in COPD patients, and thus, exercise testing has been traditionally used for the functional evaluation of these patients. Compared to various laboratory and field exercise tests, cardiopulmonary exercise testing (CPET) provides a thorough assessment of exercise physiology, involving the integrative respiratory, cardiovascular, muscle and metabolic responses to exercise. This review highlights the clinical utility of CPET in COPD patients, as it provides important information for the determination of the major factors that limit exercise among patients with several comorbidities, allows the assessment of the severity of dynamic hyperinflation, provides valuable prognostic information and can be used to evaluate the response to several therapeutic interventions.

Clinical and Physiologic Implications of Negative Cardiopulmonary Interactions in Coexisting Chronic Obstructive Pulmonary Disease-Heart Failure

Chronic obstructive pulmonary disease (COPD) and heart failure with reduced ejection fraction (HF) frequently coexist in the elderly. Expiratory flow limitation and lung hyperinflation due to COPD may adversely affect central hemodynamics in HF. Low lung compliance, increased alveolar-capillary membrane thickness, and abnormalities in pulmonary perfusion because of HF further deteriorates lung function in COPD. We discuss how those negative cardiopulmonary interactions create challenges in clinical interpretation of pulmonary function and cardiopulmonary exercise tests in coexisting COPD-HF. In the light of physiologic concepts, we also discuss the influence of COPD or HF on the current medical treatment of each disease.