Use of exercise testing in the evaluation of interventional efficacy: an official ERS statement

Effect of Home-Based Pulmonary Rehabilitation on Pulmonary Fibrosis

BACKGROUND

Pulmonary fibrosis is a chronic, progressive lung condition that involves lung tissue scarring and thickening. The effects of home-based pulmonary rehabilitation (PR) in post-covid pulmonary fibrosis (PCPF) and other forms of fibrosis together have not been evaluated. This study aims to evaluate the effectiveness of home-based pulmonary rehabilitation on pulmonary function, functional capacity, and health-related quality of life in people with pulmonary fibrosis (post-COVID pulmonary fibrosis, pulmonary fibrosis secondary to pulmonary tuberculosis (TB), pulmonary fibrosis secondary to interstitial lung disease (ILD), pulmonary fibrosis secondary to bronchiectasis).

METHODS

A single-group pretest-posttest experimental study was performed after recruiting 98 pulmonary fibrosis subjects from K.M.C hospitals. After being screened for the inclusion and exclusion criteria, 45 subjects were analyzed, and 6 subjects were lost to follow-up.  A home-based pulmonary rehabilitation program was carried out for 8 weeks (warm-up, stretching exercises, aerobic exercise, strength training for upper limb and lower limb, breathing exercises mainly involved; others: energy saving techniques, controlled coughing techniques, dyspnea relieving positions). The program was supervised via weekly phone calls. Pulmonary function (Pulmonary function test), exercise capacity (6-minute walk test), dyspnea (modified Borg scale), and health-related quality of life (SF-36) were evaluated before and after the intervention. During the enrollment and after the 6-minute walk test, saturation of peripheral oxygen (SPO2) level was also evaluated pre-intervention and after the 8-weeks program.

RESULTS

Pulmonary function [FVC(L) t = -12.52, p<0.05; FEV1(L) t = -2.56, p<0.05; FEV1/FVC t = 7.98, p<0.05 and DLCO (ml/min/mmHg) t = -5.13, p<0.05], 6MWD [MD 88.66; p<0.05] and HRQOL measured by SF-36 scores (p<0.05) were improved significantly. Both the baseline SPO2 level before the 6MWT [MD 1.07, p<0.05] and the SPO2 level after the 6MWT [MD 1.16, p<0.05] showed a significant improvement. The rating of perceived exertion(dyspnea) [MD 1.30, p<0.05] was reduced significantly after the 8-week program.

CONCLUSION

Our study shows that home-based pulmonary rehabilitation is an effective option for improving lung function and physical functional capacity by reducing dyspnea perception and improving the saturation of peripheral oxygen (SPO2) level, and enhancing the quality of life in people with pulmonary fibrosis.

Clinical utility of the Borg dyspnoea score in 6-minute walk tests in interstitial lung disease: A systematic review

BACKGROUND

Exertional dyspnoea, a cardinal symptom in interstitial lung disease (ILD), can be objectively measured during a 6-min walk test (6MWT) using the Borg Dyspnoea Score (BDS). However, the clinical utility of this measurement is unclear. The purpose of this systematic review was to determine the association between 6MWT BDS and prognosis (mortality and lung transplantation), other 6MWT variables and measures of pulmonary function.

METHODS

MEDLINE, EMBASE, Cochrane and SCOPUS databases were used to identify studies reporting an association between post-6MWT BDS and the relevant outcomes in adults with ILD. Language was limited to English. Study quality was assessed using the Quality in Prognosis Study risk of bias tool. A narrative synthesis for each outcome was performed.

RESULTS

Ten full-text studies (n = 518) were included. Four studies had high overall risk of bias. Two studies (n = 127) reported prognosis and both found that higher 6MWT BDS was associated with increased all-cause mortality. However, the certainty of evidence was very low due to study design and likely publication bias. Higher post-6MWT BDS may be associated with shorter, or no effect on 6MWD; and lower pulmonary function. There was insufficient evidence that BDS correlated with 6MWT oxygen saturation.

CONCLUSIONS

Post-6MWT BDS has a potential role as a predictor of all-cause mortality in ILD, 6MWD and lower pulmonary function. Larger studies designed to confirm these relationships and assess the independent association between the 6MWT BDS and clinical outcomes are required.

Ventilatory efficiency in long-term dyspnoeic patients following COVID-19 pneumonia

BACKGROUND

Long COVID is defined as persistency of symptoms, such as exertional dyspnea, twelve weeks after recovery from SARS-CoV-2 infection.

OBJECTIVES

To investigate ventilatory efficiency by the use of cardiopulmonary exercise testing (CPET) in patients with exertional dyspnea despite normal basal spirometry after 18 (T18) and 36 months (T36) from COVID-19 pneumonia.

METHODS

One hundred patients with moderate-critical COVID-19 were prospectively enrolled in our Long COVID program. Medical history, physical examination and lung high-resolution computed tomography (HRCT) were obtained at hospitalization (T0), 3 (T3) and 15 months (T15). All HRCTs were revised using a semi-quantitative CT severity score (CSS). Pulmonary function tests were obtained at T3 and T15. CPET was performed in a subset of patients with residual dyspnea (mMRC ≥ 1), at T18 and at T36.

RESULTS

Remarkably, at CPET, ventilatory efficiency was reduced both at T18 (V'E/V'CO2 slope = 31.4±3.9 SD) and T36 (V'E/V'CO2 slope = 31.28±3.70 SD). Furthermore, we identified positive correlations between V'E/V'CO2 slope at T18 and T36 and both percentage of involvement and CSS at HRCT at T0, T3 and T15. Also, negative linear correlations were found between V'E/V'CO2 slope at T18 and T36 and DLCO at T3 and T15.

CONCLUSIONS

At eighteen months from COVID-19 pneumonia, 20 % of subjects still complains of exertional dyspnea. At CPET this may be explained by persistently reduced ventilatory efficiency, possibly related to the degree of lung parenchymal involvement in the acute phase of infection, likely reflecting a damage in the pulmonary circulation.

Validation of Constant Work Rate Cycling Endurance Time for Use in Chronic Obstructive Pulmonary Disease Clinical Trials

Rationale: A COPD Foundation working group sought to identify measures of exercise endurance, a meaningful aspect of physical functioning in everyday life among patients with chronic obstructive pulmonary disease (COPD) that is not fully accepted in regulatory decision making, hampering drug development. Objectives: To demonstrate, as we previously asserted (Casaburi COPD 2022;9:252), that constant work rate cycling endurance time is an appropriate exercise endurance measure in patients with COPD. Methods: To validate this assertion, we assembled an integrated database of endurance time responses, including 8 bronchodilator (2,166 subjects) and 15 exercise training (3,488 subjects) studies (Casaburi COPD 2022;9:520). Results: Construct validity was demonstrated: 1) peak physiologic and perceptual responses were similar for constant work rate and incremental cycling; 2) after bronchodilator therapy, there were greater increases in endurance time in patients with more severe airflow limitation; 3) after exercise training, endurance time increases were similar across airflow limitation severities; and 4) there were correlations between changes in endurance time and changes in mechanistically related physiologic and perceptual variables. Test-retest reliability was demonstrated, with consistency of changes in endurance time at two time points after the intervention. Responsiveness was confirmed, with significant increases in endurance time after active (but not placebo) bronchodilator therapy, with greater increases seen with more severe airflow limitation and after exercise training. On the basis of regression analysis using multiple anchor variables, the minimum important difference for endurance time increase is estimated to be approximately 1 minute. Conclusions: Constant work rate cycling endurance time is a valid exercise endurance measure in COPD, suitable for contributing to the evaluation of treatment benefit supporting regulatory decision making and evidence-based therapeutic recommendations.

Effects of Combined Endurance and Resistance Eccentric Training on Muscle Function and Functional Performance in Patients With Chronic Obstructive Pulmonary Disease: Randomized Controlled Trial

OBJECTIVE

To evaluate the adherence to treatment and efficacy of an eccentric-based training (ECC) program on peripheral muscle function and functional exercise capacity in patients with chronic obstructive pulmonary disease (COPD).

DESIGN

Prospective, assessor-blinded, randomized controlled trial.

SETTING

The cardiopulmonary rehabilitation unit of a tertiary subacute referral center.

PARTICIPANTS

Thirty (N=30) stable inpatients (mean age 68±8 years; FEV1 44±18% of predicted) with COPD were included in the study.

INTERVENTIONS

Inpatients were randomly assigned to 4 weeks of a combined endurance and resistance ECC (n=15) or conventional training (CON; n=15).

MAIN OUTCOME MEASURES

Quadriceps peak torque (PT) was the primary outcome measure for muscle function. Rate of force development (RFD), muscle activation and quality (quadriceps PT/leg lean mass), 6-min walk distance (6MWD), 4-meter gait speed (4mGS), 10-meter gait speed, 5-repetition sit-to-stand (5STS), dyspnea rate, and mortality risk were the secondary outcomes. Evaluations were performed at baseline and repeated after 4 weeks and 3 months of follow-up.

RESULTS

Quadriceps PT, RFD, and muscle quality improved by 17±23% (P<.001), 19±24%, and 16±20% (both P<.05) within the ECC group. Besides, a significant between-group difference for RFD (56±94 Nm/s, P=.038) was found after training. Both groups showed clinically relevant improvements in 6MWD, 4mGS, dyspnea rate, and mortality risk, with no significant differences between groups.

CONCLUSION

Combined endurance and resistance ECC improved lower limbs muscle function compared with CON in inpatients with COPD. In contrast, ECC did not further improve functional performance, dyspnea, and mortality risk. ECC may be of particular benefit to effect on skeletal muscle function in patients with COPD.

Feasibility of Constant Work Rate Testing to Detect Exercise-Induced Laryngeal Obstruction

INTRODUCTION

Exercise-induced laryngeal obstruction (EILO) is a condition in which laryngeal structures inappropriately obstruct the upper airway during exercise. The standard diagnostic test for EILO is the continuous laryngoscopy during exercise (CLE) test, usually performed with an incremental work rate protocol regardless of the nature of the triggering event. Typically, laryngeal obstruction occurs only briefly at the end of an incremental test, near peak work capacity. We aimed to investigate constant work rate (CWR) protocols for CLE testing to expand diagnostic test modalities and improve the understanding of EILO.

METHODS

In this prospective, self-controlled feasibility study, 10 patients with EILO performed both an incremental and a CWR CLE test at 70%, 80%, and 90% of maximal exercise capacity. Laryngoscopic video data were recorded and compared, and we evaluated the ability of CWR to reproduce the symptoms and laryngeal obstruction seen in incremental testing.

RESULTS

In 70%-90% of cases, CWR testing induced at least the same severity of obstruction as incremental testing and CLE scores remained comparable across test modalities. CWR at 70% allowed observation of laryngeal obstruction for a significantly longer duration than in incremental testing (158 s; 95% confidence interval, 25-291 s; P = 0.027). Dyspnea intensity appeared higher during CWR testing compared with incremental testing.

CONCLUSIONS

Submaximal CWR CLE testing is feasible and able to induce EILO equivalent to the standard incremental CLE test. This is the first step toward tailored CLE exercise protocols, and further studies are now needed to establish the utility of CWR in clinical and research settings.

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.

Lack of effect of an in-line filter on cardiopulmonary exercise testing variables in healthy subjects

PURPOSE

Pathogen transmission during cardio-pulmonary exercise testing (CPET) is caused by carrier aerosols generated during respiration.

METHODS

Ten healthy volunteers (age range: 34 ± 15; 4 females) were recruited to see if the physiological reactions to ramp-incremental CPET on a cycle ergometer were affected using an in-line filter placed between the mouthpiece and the flow sensor. The tests were in random order with or without an in-line bacterial/viral spirometer filter. The work rate aligned, time interpolated 10 s bin data were compared throughout the exercise period.

RESULTS

From rest to peak exercise, filter use increased only minute ventilation ([Formula: see text]E) (Δ[Formula: see text]E = 1.56 ± 0.70 L/min, P < 0.001) and tidal volume (VT) (ΔVT = 0.10 ± 0.11 L, P = 0.014). Over the entire test, the slope of the residuals for [Formula: see text]CO2 was positive (0.035 ± 0.041 (ΔL/L), P = 0.027). During a ramp-incremental CPET in healthy subjects, an in-line filter increased [Formula: see text]E and VT but not metabolic rate.

CONCLUSION

In conclusion, using an in-line filter is feasible, does not affect appreciably the physiological variables, and may mitigate risk of aerosol dispersion during CPET.

Abnormal Exertional Breathlessness on Cardiopulmonary Cycle Exercise Testing in Relation to Self-Reported and Physiologic Responses in Chronic Airflow Limitation

BACKGROUND

Exertional breathlessness is a cardinal symptom of cardiorespiratory disease.

RESEARCH QUESTION

How does breathlessness abnormality, graded using normative reference equations during cardiopulmonary exercise testing (CPET), relate to self-reported and physiologic responses in people with chronic airflow limitation (CAL)?

STUDY DESIGN AND METHODS

An analysis was done of people aged ≥ 40 years with CAL undergoing CPET in the Canadian Cohort Obstructive Lung Disease study. Breathlessness intensity ratings (Borg CR10 scale [0-10 category-ratio scale for breathlessness intensity rating]) were evaluated in relation to power output, rate of oxygen uptake, and minute ventilation at peak exercise, using normative reference equations as follows: (1) probability of breathlessness normality (probability of having an equal or greater Borg CR10 rating among healthy people; lower probability reflecting more severe breathlessness) and (2) presence of abnormal breathlessness (rating above the upper limit of normal). Associations with relevant participant-reported and physiologic outcomes were evaluated.

RESULTS

We included 330 participants (44% women): mean ± SD age, 64 ± 10 years (range, 40-89 years); FEV1/FVC, 57.3% ± 8.2%; FEV1, 75.6% ± 17.9% predicted. Abnormally low exercise capacity (peak rate of oxygen uptake < lower limit of normal) was present in 26%. Relative to peak power output, rate of oxygen uptake, and minute ventilation, abnormally high breathlessness was present in 26%, 25%, and 18% of participants. For all equations, abnormally high exertional breathlessness was associated with worse lung function, exercise capacity, self-reported symptom burden, physical activity, and health-related quality of life; and greater physiologic abnormalities during CPET.

INTERPRETATION

Abnormal breathlessness graded using CPET normative reference equations was associated with worse clinical, physiological, and functional outcomes in people with CAL, supporting construct validity of abnormal exertional breathlessness.

Comparison of the Effects of Two Different Exercise Programs on Lower Limb Functions, Posture, and Physical Activity in Office Workers Working at Home and in Office Alternately: A Randomized Controlled Trial

OBJECTIVE

The aim of this study was to compare the effects of online functional exercises and posture exercises on lower limb functions, posture, and physical activity in office workers working at home and in office alternately during the COVID-19 pandemic.

DESIGN

Forty individuals were included in the study and were randomized into two groups: group I (functional exercise group, 20 participants) and group II (posture exercise group, 20 participants). The exercises programs were performed online for 2 days/in a week/8 wk. Lower limb functions, posture, and physical activity were evaluated before and after the exercise program.

RESULT

Significant improvement was obtained in lower limb functions (muscular endurance, balance, and functional capacity), posture, and physical activity in group I, while significant improvement was obtained in balance and functional capacity in group II after treatment. The change in scores of lower limb functions, posture, and physical activity after treatment was statistically superior in group I compared with group II ( P < 0.05).

CONCLUSIONS

It was found that both online exercise programs provided effective results in office workers working at home and in office alternately due to the COVID-19 pandemic, but the functional exercise program had superior effects on lower limb functions, posture, and physical activity compared with the posture exercise program.

Perioperative Exercise Testing in Pregnant and Non-Pregnant Women of Reproductive Age: A Systematic Review

BACKGROUND

Women have classically been excluded from the development of normal data and reference ranges, with pregnant women experiencing further neglect. The incidence of Caesarean section in pregnant women, and of general operative management in young women (both pregnant and non-pregnant), necessitates the formal development of healthy baseline data in these cohorts to optimise their perioperative management. This systematic review assesses the representation of young women in existing reference ranges for several functional exercise tests in common use to facilitate functional assessment in this cohort.

METHODS

Existing reference range data for the exercise tests the Six Minute Walk Test (6MWT), the Incremental Shuttle Walk Test (ISWT) and Cardiopulmonary Exercise Testing (CPET) in young women of reproductive age were assessed using the MEDLINE (Ovid) database, last searched December 2023. Results were comparatively tabulated but not statistically analysed given underlying variances in data.

RESULTS

The role of exercise testing in the perioperative period as an assessment tool, as well as its safety during pregnancy, was evaluated using 65 studies which met inclusion criteria.

CONCLUSION

There is a significant lack of baseline data regarding these tests in this population, especially amongst the pregnant cohort, which limits the application of exercise testing clinically.

Normative Reference Equations for Breathlessness Intensity during Incremental Cardiopulmonary Cycle Exercise Testing

Rationale: Cardiopulmonary exercise testing (CPET) is the gold standard to evaluate exertional breathlessness, a common and disabling symptom. However, the interpretation of breathlessness responses to CPET is limited by a scarcity of normative data. Objectives: We aimed to develop normative reference equations for breathlessness intensity (Borg 0-10 category ratio) response in men and women aged ⩾40 years during CPET, in relation to power output (watts), oxygen uptake, and minute ventilation. Methods: Analysis of ostensibly healthy people aged ⩾40 years undergoing symptom-limited incremental cycle CPET (10 W/min) in the CanCOLD (Canadian Cohort Obstructive Lung Disease) study. Participants had smoking histories <5 pack-years and normal lung function and exercise capacity. The probability of each Borg 0-10 category ratio breathlessness intensity rating by power output, oxygen uptake, and minute ventilation (as an absolute or a relative value [percentage of predicted maximum]) was predicted using ordinal multinomial logistic regression. Model performance was evaluated by fit, calibration, and discrimination (C statistic) and externally validated in an independent sample (n = 86) of healthy Canadian adults. Results: We included 156 participants (43% women) from CanCOLD; the mean age was 65 (range, 42-91) years, and the mean body mass index was 26.3 (standard deviation, 3.8) kg/m2. Reference equations were developed for women and men separately, accounting for age and/or body mass. Model performance was high across all equations, including in the validation sample (C statistic for men = 0.81-0.92, C statistic for women = 0.81-0.96). Conclusions: Normative reference equations are provided to compare exertional breathlessness intensity ratings among individuals or groups and to identify and quantify abnormal breathlessness responses (scores greater than the upper limit of normal) during CPET.

Laryngeal widening and adequate ventilation by expiratory pressure load training improve aerobic capacity in COPD: a randomised controlled trial

RATIONALE

Despite strategies acting on peripheral airway obstruction in chronic obstructive pulmonary disease (COPD), exercise intolerance remains inadequately improved. We hypothesised that laryngeal narrowing is a potential treatment target of expiratory pressure load training (EPT) to improve exercise intolerance in COPD.

METHODS

The effect of 3-month EPT was assessed in 47 patients with COPD divided into Global Initiative for Chronic Obstructive Lung Disease (GOLD) mild-to-moderate (I-II) and severe-to-very severe (III-IV), randomly allocating 1:1 to EPT or control groups. The primary outcome was endurance time in the constant work rate exercise test in GOLD III-IV patients.

RESULTS

Compared with controls, EPT increased: (1) endurance time, with estimated treatment effect: +703 (95% CI: 379 to 1031) s, p=0.0008 (GOLD I-II); +390 (95% CI: 205 to 574) s, p=0.0006 (GOLD III-IV); (2) peak oxygen uptake (p=0.0086 in GOLD I-II; p=0.0004 in GOLD III-IV); (3) glottic dilatation ratio at maximum collapse on laryngoscopy in the submaximal exercise (p=0.0062 in GOLD I-II; p=0.0001 in GOLD III-IV); and (4) the inflection point of expiratory tidal volume relative to minute ventilation during the incremental exercise (p=0.0015 in GOLD I-II; p=0.0075 in GOLD III-IV). Across GOLD grades, the responses of glottic dilatation ratio at maximum collapse and the expiratory tidal volume at the inflection point were selected as more influential variables correlating with the improvement in peak oxygen uptake and endurance time, respectively.

CONCLUSION

These results show that EPT improved aerobic capacity and endurance time with larger laryngeal widening and adequate ventilation despite advanced COPD.

TRIAL REGISTRATION NUMBER

UMIN000041250.

Can static hyperinflation predict exercise capacity in COPD?

INTRODUCTION

The diagnosis and severity assessment of COPD relies on spirometry, and in particular the FEV1. However, it has been proposed that hyperinflation and air-trapping are better predictors of exercise capacity and mortality than the FEV1.

RESEARCH

QUESTION: Does static hyperinflation predict exercise capacity?

METHODS

We conducted an observational prospective study. Patients with COPD referred to the lung function laboratory were consecutively recruited. Patients with hyperinflation (the experimental group) were compared to patients without hyperinflation (the control group). The sample sizes were determined assuming an effect size of 0.5 and a power of 0.80.

RESULTS

We recruited 124 participants, of whom 87% were male, the mean age was 66.1 ± 8.8 years. 67% were symptomatic (GOLD B or D). Airflow limitation was moderate to severe in the majority of patients (median FEV1 47%, IQR 38-65%) and 43% of patients had static hyperinflation. The median 6MWD was 479 meters (404-510) and peak workload in CPET was 64 watts (46-88) with peak VO2 1.12 L/min, 0.89-1.31 L/min. Patients with lower FEV1, DLCO and IC/TLC and higher RV/TLC had reduced exercise capacity in both 6MWT and CPET, measured as lower distance, greater desaturation and ∆Borg dyspnoea, and reduced workload, peak VO2 and peak VE and higher desaturation and ventilatory limitation (VE/MVV). An IC/TLC < 0.33 predicted reduced exercise performance (peak O2 <60%). Dyspnoea assessed by mMRC and QoL measured by CAT and CCQ were also worse in the hyperinflation in COPD patients.

CONCLUSION

In COPD patients, IC/TLC and RV/TLC are valuable predictors of exercise performance in both 6MWT and CPET and PRO.

Monitoring Changes in Oxygen Muscle during Exercise with High-Flow Nasal Cannula Using Wearable NIRS Biosensors

Exercise increases the cost of breathing (COB) due to increased lung ventilation (V˙E), inducing respiratory muscles deoxygenation (∇SmO2), while the increase in workload implies ∇SmO2 in locomotor muscles. This phenomenon has been proposed as a leading cause of exercise intolerance, especially in clinical contexts. The use of high-flow nasal cannula (HFNC) during exercise routines in rehabilitation programs has gained significant interest because it is proposed as a therapeutic intervention for reducing symptoms associated with exercise intolerance, such as fatigue and dyspnea, assuming that HFNC could reduce exercise-induced ∇SmO2. SmO2 can be detected using optical wearable devices provided by near-infrared spectroscopy (NIRS) technology, which measures the changes in the amount of oxygen bound to chromophores (e.g., hemoglobin, myoglobin, cytochrome oxidase) at the target tissue level. We tested in a study with a cross-over design whether the muscular desaturation of m.vastus lateralis and m.intercostales during a high-intensity constant-load exercise can be reduced when it was supported with HFNC in non-physically active adults. Eighteen participants (nine women; age: 22 ± 2 years, weight: 65.1 ± 11.2 kg, height: 173.0 ± 5.8 cm, BMI: 21.6 ± 2.8 kg·m-2) were evaluated in a cycle ergometer (15 min, 70% maximum watts achieved in ergospirometry (V˙O2-peak)) breathing spontaneously (control, CTRL) or with HFNC support (HFNC; 50 L·min-1, fiO2: 21%, 30 °C), separated by seven days in randomized order. Two-way ANOVA tests analyzed the ∇SmO2 (m.intercostales and m.vastus lateralis), and changes in V˙E and ∇SmO2·V˙E-1. Dyspnea, leg fatigue, and effort level (RPE) were compared between trials by the Wilcoxon matched-paired signed rank test. We found that the interaction of factors (trial × exercise-time) was significant in ∇SmO2-m.intercostales, V˙E, and (∇SmO2-m.intercostales)/V˙E (p < 0.05, all) but not in ∇SmO2-m.vastus lateralis. ∇SmO2-m.intercostales was more pronounced in CTRL during exercise since 5' (p < 0.05). Hyperventilation was higher in CTRL since 10' (p < 0.05). The ∇SmO2·V˙E-1 decreased during exercise, being lowest in CTRL since 5'. Lower dyspnea was reported in HFNC, with no differences in leg fatigue and RPE. We concluded that wearable optical biosensors documented the beneficial effect of HFNC in COB due to lower respiratory ∇SmO2 induced by exercise. We suggest incorporating NIRS devices in rehabilitation programs to monitor physiological changes that can support the clinical impact of the therapeutic intervention implemented.

Current definitions of the breathing cycle in alveolar breath-by-breath gas exchange analysis

Identification of the breathing cycle forms the basis of any breath-by-breath gas exchange analysis. Classically, the breathing cycle is defined as the time interval between the beginning of two consecutive inspiration phases. Based on this definition, several research groups have developed algorithms designed to estimate the volume and rate of gas transferred across the alveolar membrane ("alveolar gas exchange"); however, most algorithms require measurement of lung volume at the beginning of the ith breath (VLi-1; i.e., the end-expiratory lung volume of the preceding ith breath). The main limitation of these algorithms is that direct measurement of VLi-1 is challenging and often unavailable. Two solutions avoid the requirement to measure VLi-1 by redefining the breathing cycle. One method defines the breathing cycle as the time between two equal fractional concentrations of lung expired oxygen (Fo2) (or carbon dioxide; Fco2), typically in the alveolar phase, whereas the other uses the time between equal values of the Fo2/Fn2 (or Fco2/Fn2) ratios [i.e., the ratio of fractional concentrations of lung expired O2 (or CO2) and nitrogen (N2)]. Thus, these methods identify the breathing cycle by analyzing the gas fraction traces rather than the gas flow signal. In this review, we define the traditional approach and two alternative definitions of the human breathing cycle and present the rationale for redefining this term. We also explore the strengths and limitations of the available approaches and provide implications for future studies.

2023 Canadian Thoracic Society Guideline on Pharmacotherapy in Patients With Stable COPD

Chronic obstructive pulmonary disease patient care must include confirming a diagnosis with postbronchodilator spirometry. Because of the clinical heterogeneity and the reality that airflow obstruction assessed by spirometry only partially reflects disease severity, a thorough clinical evaluation of the patient should include assessment of symptom burden and risk of exacerbations that permits the implementation of evidence-informed pharmacologic and nonpharmacologic interventions. This guideline provides recommendations from a comprehensive systematic review with a meta-analysis and expert-informed clinical remarks to optimize maintenance pharmacologic therapy for individuals with stable COPD, and a revised and practical treatment pathway based on new evidence since the 2019 update of the Canadian Thoracic Society (CTS) Guideline. The key clinical questions were developed using the Patients/Population (P), Intervention(s) (I), Comparison/Comparator (C), and Outcome (O) model for three questions that focuses on the outcomes of symptoms (dyspnea)/health status, acute exacerbations, and mortality. The evidence from this systematic review and meta-analysis leads to the recommendation that all symptomatic patients with spirometry-confirmed COPD should receive long-acting bronchodilator maintenance therapy. Those with moderate to severe dyspnea (modified Medical Research Council ≥ 2) and/or impaired health status (COPD Assessment Test ≥ 10) and a low risk of exacerbations should receive combination therapy with a long-acting muscarinic antagonist/long-acting ẞ2-agonist (LAMA/LABA). For those with a moderate/severe dyspnea and/or impaired health status and a high risk of exacerbations should be prescribed triple combination therapy (LAMA/LABA/inhaled corticosteroids) azithromycin, roflumilast or N-acetylcysteine is recommended for specific populations; a recommendation against the use of theophylline, maintenance systemic oral corticosteroids such as prednisone and inhaled corticosteroid monotherapy is made for all COPD patients.

Exercise Physiology and Cardiopulmonary Exercise Testing

Aerobic, or endurance, exercise is an energy requiring process supported primarily by energy from oxidative adenosine triphosphate synthesis. The consumption of oxygen and production of carbon dioxide in muscle cells are dynamically linked to oxygen uptake (V̇O2) and carbon dioxide output (V̇CO2) at the lung by integrated functions of cardiovascular, pulmonary, hematologic, and neurohumoral systems. Maximum oxygen uptake (V̇O2max) is the standard expression of aerobic capacity and a predictor of outcomes in diverse populations. While commonly limited in young fit individuals by the capacity to deliver oxygen to exercising muscle, (V̇O2max) may become limited by impairment within any of the multiple systems supporting cellular or atmospheric gas exchange. In the range of available power outputs, endurance exercise can be partitioned into different intensity domains representing distinct metabolic profiles and tolerances for sustained activity. Estimates of both V̇O2max and the lactate threshold, which marks the upper limit of moderate-intensity exercise, can be determined from measures of gas exchange from respired breath during whole-body exercise. Cardiopulmonary exercise testing (CPET) includes measurement of V̇O2 and V̇CO2 along with heart rate and other variables reflecting cardiac and pulmonary responses to exercise. Clinical CPET is conducted for persons with known medical conditions to quantify impairment, contribute to prognostic assessments, and help discriminate among proximal causes of symptoms or limitations for an individual. CPET is also conducted in persons without known disease as part of the diagnostic evaluation of unexplained symptoms. Although CPET quantifies a limited sample of the complex functions and interactions underlying exercise performance, both its specific and global findings are uniquely valuable. Some specific findings can aid in individualized diagnosis and treatment decisions. At the same time, CPET provides a holistic summary of an individual's exercise function, including effects not only of the primary diagnosis, but also of secondary and coexisting conditions.

Beyond the Lungs: O 2 Supplementation Improves Cerebral Oxygenation and Fatigue during Exercise in Interstitial Lung Disease

PURPOSE

Cerebral hypoxia may exacerbate the perception of fatigue. We previously demonstrated that exercise-related hypoxemia, a hallmark of fibrotic interstitial lung disease ( f -ILD), dose dependently impairs cerebral oxygenation in these patients. It is unknown whether normalizing cerebral oxygenation with O 2 supplementation would be associated with positive changes in a relevant patient-centered outcome during exercise in f -ILD, such as improved perceived fatigue.

METHODS

Fourteen patients (12 males, 72 ± 8 yr, 8 with idiopathic pulmonary fibrosis, lung diffusing capacity for carbon monoxide = 44% ± 13% predicted) performed a constant-load (60% peak work rate) cycle test to symptom limitation (Tlim) breathing medical air. Fourteen controls cycled up to Tlim of an age- and sex-matched patient. Patients repeated the test on supplemental O 2 (fraction of inspired O 2 = 0.41 ± 0.08) for the same duration. Near-infrared spectroscopy and the rating-of-fatigue (ROF) scale assessed prefrontal cortex oxygenation and perceived fatigue, respectively.

RESULTS

Patients showed severe exertional hypoxemia (Tlim O 2 saturation by pulse oximetry = 80% ± 8%); they had poorer cerebral oxygenation (e.g., oxy-deoxyhemoglobin difference [HbDiff] = -3.5 ± 4.7 [range = -17.6 to +1.9] vs +1.9 ± 1.7 μmol from rest) and greater fatigue (ROF = 6.2 ± 2.0 vs 2.6 ± 2.3) versus controls under air ( P < 0.001). Reversal of exertional hypoxemia with supplemental O 2 led to improved HbDiff (+1.7 ± 2.4 μmol from rest; no longer differing from controls) and lower ROF scores (3.7 ± 1.2, P < 0.001 vs air) in patients. There was a significant correlation between O 2 -induced changes in HbDiff and ROF scores throughout exercise in f -ILD ( rrepeated-measures correlation = -0.51, P < 0.001).

CONCLUSIONS

Supplemental O 2 improved cerebral oxygenation during exercise in f -ILD, which was moderately associated with lower ratings of perceived fatigue. Reversing cerebral hypoxia with O 2 supplementation may thus have positive effects on patients' disablement beyond those expected from lower ventilation and dyspnea in this patient population.

Fixed-intensity exercise tests to measure exertional dyspnoea in chronic heart and lung populations: a systematic review

INTRODUCTION

Exertional dyspnoea is the primary diagnostic symptom for chronic cardiopulmonary disease populations. Whilst a number of exercise tests are used, there remains no gold standard clinical measure of exertional dyspnoea. The aim of this review was to comprehensively describe and evaluate all types of fixed-intensity exercise tests used to assess exertional dyspnoea in chronic cardiopulmonary populations and, where possible, report the reliability and responsiveness of the tests.

METHODS

A systematic search of five electronic databases identified papers that examined 1) fixed-intensity exercise tests and measured exertional dyspnoea, 2) chronic cardiopulmonary populations, 3) exertional dyspnoea reported at isotime or upon completion of fixed-duration exercise tests, and 4) published in English.

RESULTS

Searches identified 8785 papers. 123 papers were included, covering exercise tests using a variety of fixed-intensity protocols. Three modes were identified, as follows: 1) cycling (n=87), 2) walking (n=31) and 3) other (step test (n=8) and arm exercise (n=2)). Most studies (98%) were performed on chronic respiratory disease patients. Nearly all studies (88%) used an incremental exercise test. 34% of studies used a fixed duration for the exercise test, with the remaining 66% using an exhaustion protocol recording exertional dyspnoea at isotime. Exertional dyspnoea was measured using the Borg scale (89%). 7% of studies reported reliability. Most studies (72%) examined the change in exertional dyspnoea in response to different interventions.

CONCLUSION

Considerable methodological variety of fixed-intensity exercise tests exists to assess exertional dyspnoea and most test protocols require incremental exercise tests. There does not appear to be a simple, universal test for measuring exertional dyspnoea in the clinical setting.

The modified Borg/6-min walk distance ratio: a method to assess exertional breathlessness and leg discomfort using the 6-min walk test

Background

The 6-min walk test (6MWT) is widely used to assess exercise capacity across chronic health conditions, but is currently not useful to assess symptoms, as the scores do not account for the 6-min walk distance (6MWD). We aimed to 1) develop normative reference equations for breathlessness and leg discomfort intensity expressed as modified Borg (mBorg)/6MWD ratios; and 2) validate the equations in people with COPD.

Methods

Analysis of people aged ≥40 years who performed two 6MWTs (on a 20-m course) in the Canadian Cohort Obstructive Lung Disease (CanCOLD) study: a healthy cohort (n=291; mean±sd age 67.5±9.4 years; 54% male) with normal 6MWD and lung function, and a COPD cohort (n=156; age 66.2±9.0 years; 56% male; forced expiratory volume in 1 s (FEV1)/forced vital capacity 56.6±8.2%; FEV1 74.4±18.6% pred). The mBorg score was calculated as the Borg 0-10 category ratio intensity rating of breathlessness or leg discomfort recorded at the end of the 6MWT +1 (range 1-11), to avoid zeros and yield ratios proportional to the symptom score and 6MWD-1.

Results

Using data from the healthy cohort, sex-specific normative reference equations for breathlessness and leg discomfort mBorg/6MWD ratios were developed using multivariable linear regression, accounting for age, and body mass or body mass index. In the COPD cohort, abnormal breathlessness and leg discomfort (mBorg/6MWD>upper limit of normal) showed strong concurrent validity with worse airflow limitation, Medical Research Council breathlessness and COPD Assessment Test scores.

Conclusion

Normative references for the mBorg/6MWD ratio are presented to assess breathlessness and leg discomfort responses to the 6MWT in COPD.

An Update on Outcomes for COPD Pharmacological Trials: A COPD Investigators Report - Reassessment of the 2008 American Thoracic Society/European Respiratory Society Statement on Outcomes for COPD Pharmacological Trials

Background: In 2008, a dedicated American Thoracic Society/European Respiratory Society task force published a paper on the possible use and limitations of clinical outcomes and biomarkers to evaluate the impact of pharmacological therapy in patients with chronic obstructive pulmonary disease. Since then, our scientific understanding of chronic obstructive pulmonary disease has increased considerably; there has been a progressive shift from a one-size-fits-all diagnostic and therapeutic approach to a personalized approach; and many new treatments currently in development will require new endpoints to evaluate their efficacy adequately. Objectives: The emergence of several new relevant outcome measures motivated the authors to review advances in the field and highlight the need to update the content of the original report. Methods: The authors separately created search strategies for the literature, primarily based on their opinions and assessments supported by carefully chosen references. No centralized examination of the literature or uniform criteria for including or excluding evidence were used. Measurements and Main Results: Endpoints, outcomes, and biomarkers have been revisited. The limitations of some of those reported in the American Thoracic Society/European Respiratory Society task force document have been highlighted. In addition, new tools that may be useful, especially in evaluating personalized therapy, have been described. Conclusions: Because the "label-free" treatable traits approach is becoming an important step toward precision medicine, future clinical trials should focus on highly prevalent treatable traits, and this will influence the choice of outcomes and markers to be considered. The use of the new tools, particularly combination endpoints, could help better identify the right patients to be treated with the new drugs.

Prognostic Value of Pace Variability, a Novel 6MWT-Derived Feature, in Patients with Chronic Obstructive Pulmonary Disease

Purpose

The 6-minute walk test (6MWT) is often used to evaluate chronic obstructive pulmonary disease (COPD) patients' functional capacity, with 6-minute walk distance (6MWD) and related measures being linked to mortality and hospitalizations. This study investigates the prognostic value of pace variability, a significant indicator in sports medicine, during the 6MWT for COPD patients.

Patients and Methods

We retrospectively screened consecutive COPD patients who had been prospectively enrolled in a pay-for-performance program from January 2019 to May 2020 to determine their eligibility. Patient characteristics, including demographics, exacerbation history, and 6MWT data, were analyzed to investigate their potential associations with prognosis. The primary outcome was a composite of adverse events, including overall mortality or hospitalizations due to exacerbations during a 1-year follow-up period. To analyze the 6MWT data, we divided it into three 2-minute epochs and calculated the average walk speed for each epoch. We defined pace variability as the difference between the maximum and minimum average speed in a single 2-minute epoch, divided by the average speed for the entire 6-minute walk test.

Results

A total of 163 patients with COPD were included in the study, and 19 of them (12%) experienced the composite adverse outcome. Multivariable logistic regression analyses revealed that two predictors were independently associated with the composite outcome: % predicted 6MWD <72 (adjusted odds ratio [aOR] 7.080; 95% confidence interval [CI] 1.481-33.847) and pace variability ≥0.39 (aOR 9.444; 95% CI 2.689-33.170). Patients with either of these adverse prognostic features had significantly worse composite outcome-free survival, with both log-rank P values less than 0.005. Notably, COPD patients with both adverse features experienced an especially poor outcome after 1 year.

Conclusion

Patients with COPD who exhibited greater pace variability during the 6MWT had a significantly higher risk of overall mortality and COPD-related hospitalizations, indicating a worse prognosis.

Cardiopulmonary exercise testing before and after intravenous iron in preoperative patients: a prospective clinical study

BACKGROUND

Anemia is associated with impaired physical performance and adverse perioperative outcomes. Iron-deficiency anemia is increasingly treated with intravenous iron before elective surgery. We explored the relationship between exercise capacity, anemia, and total hemoglobin mass (tHb-mass) and the response to intravenous iron in anemic patients prior to surgery.

METHODS

A prospective clinical study was undertaken in patients having routine cardiopulmonary exercise testing (CPET) with a hemoglobin concentration ([Hb]) < 130 g^.l^-1 and iron deficiency/depletion. Patients underwent CPET and tHb-mass measurements before and a minimum of 14 days after receiving intravenous (i.v.) Ferric derisomaltose (Monofer®) at the baseline visit. Comparative analysis of hematological and CPET variables was performed pre and post-iron treatment.

RESULTS

Twenty-six subjects were recruited, of whom 6 withdrew prior to study completion. The remaining 20 (9 [45%] male; mean ± SD age 68 ± 10 years) were assessed 25 ± 7 days between baseline and the final visit. Following i.v. iron, increases were seen in [Hb] (mean ± SD) from 109 ± 14 to 116 ± 12 g l^-1 (mean rise 6.4% or 7.3 g l^-1, p =  < 0.0001, 95% CI 4.5-10.1); tHb-mass from 497 ± 134 to 546 ± 139 g (mean rise 9.3% or 49 g, p =  < 0.0001, 95% CI 29.4-69.2). Oxygen consumption at anerobic threshold ([Formula: see text] O_{2 AT}) did not change (9.1 ± 1.7 to 9.8 ± 2.5 ml kg^-1 min^-1, p = 0.09, 95% CI - 0.13 - 1.3). Peak oxygen consumption ([Formula: see text] O_{2 peak}) increased from 15.2 ± 4.1 to 16 ± 4.4 ml^.kg^.-1 min^-1, p = 0.02, 95% CI 0.2-1.8) and peak work rate increased from 93 [67-112] watts to 96 [68-122] watts (p = 0.02, 95% CI 1.3-10.8).

CONCLUSION

Preoperative administration of intravenous iron to iron-deficient/deplete anemic patients is associated with increases in [Hb], tHb-mass, peak oxygen consumption, and peak work rate. Further appropriately powered prospective studies are required to ascertain whether improvements in tHb-mass and performance in turn lead to reductions in perioperative morbidity.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT 033 46213.

SARS-CoV-2 infection sequelae on exercise response: persistent or reversible? A 2-year perspective

Post-COVID-19 exercise capacity sequalae on oxygen utilisation and ventilatory efficiency improve over time in most patients. Cardiopulmonary exercise testing is a valuable tool to identify those who may benefit from specific rehabilitative interventions. https://bit.ly/3qFd97x.

Pulmonary rehabilitation and physical interventions

Pulmonary rehabilitation has established a status of evidence-based therapy for patients with symptomatic COPD in the stable phase and after acute exacerbations. Rehabilitation should have the possibility of including different disciplines and be offered in several formats and lines of healthcare. This review focusses on the cornerstone intervention, exercise training, and how training interventions can be adapted to the limitations of patients. These adaptations may lead to altered cardiovascular or muscular training effects and/or may improve movement efficiency. Optimising pharmacotherapy (not the focus of this review) and oxygen supplements, whole-body low- and high-intensity training or interval training, and resistance (or neuromuscular electrical stimulation) training are important training modalities for these patients in order to accommodate cardiovascular and ventilatory impairments. Inspiratory muscle training and whole-body vibration may also be worthwhile interventions in selected patients. Patients with stable but symptomatic COPD, those who have suffered exacerbations and patients waiting for or who have received lung volume reduction or lung transplantation are good candidates. The future surely holds promise to further personalise exercise training interventions and to tailor the format of rehabilitation to the individual patient's needs and preferences.

Risk Stratification in Pulmonary Arterial Hypertension, Update and Perspectives

Risk stratification in pulmonary arterial hypertension (PAH) is crucial in assessing patient prognosis. It serves a prominent role in everyday patient care and can be determined using several validated risk assessment scores worldwide. The recently published 2022 European Society of Cardiology (ESC)/European Respiratory Society (ERS) guidelines underline the importance of risk stratification not only at baseline but also during follow-up. Achieving a low-risk status has now become the therapeutic goal, emphasising the importance of personalised therapy. The application of these guidelines is also important in determining the timing for lung transplantation referral. In this review, we summarise the most relevant prognostic factors of PAH as well as the parameters used in PAH risk scores and their evolution in the guidelines over the last decade. Finally, we describe the central role that risk stratification plays in the current guidelines not only in European countries but also in Asian countries.

Effects of Exercise Training on Circulating Biomarkers of Endothelial Function in Pulmonary Arterial Hypertension

INTRODUCTION

In stable patients with pulmonary arterial hypertension (PAH), pulmonary rehabilitation (PR) is an effective, safe and cost-effective non-pharmacological treatment. However, the effects of PR on vascular function have been poorly explored. This study aimed to compare the amounts of circulating progenitor cells (PCs) and endothelial microvesicles (EMVs) in patients with PAH before and after 8 weeks of endurance exercise training as markers of vascular competence.

METHODS

A prospective study of 10 consecutive patients with PAH that successfully finished a PR program (8 weeks) was carried out before and after this intervention. Levels of circulating PCs defined as CD34+CD45low progenitor cells and levels of EMVs (CD31+ CD42b-) were measured by flow cytometry. The ratio of PCs to EMVs was taken as a measure of the balance between endothelial damage and repair capacity.

RESULTS

All patients showed training-induced increases in endurance time (mean change 287 s). After PR, the number of PCs (CD34+CD45low/total lymphocytes) was increased (p < 0.05). In contrast, after training, the level of EMVs (CD31+ CD42b-/total EMVs) was reduced. The ratio of PCs to EMVs was significantly higher after training (p < 0.05).

CONCLUSION

Our study shows, for the first time, that endurance exercise training in patients with stable PAH has a positive effect, promoting potential mechanisms of damage/repair in favor of repair. This effect could contribute to a positive hemodynamic and clinical response.

Bibliometric Analysis of Exercise and Chronic Obstructive Pulmonary Disease

Background

Chronic Obstructive Pulmonary Disease (COPD) is the leading cause of death in the world. Pulmonary rehabilitation includes, but is not limited to, exercise training and education, which aim to improve the physical and psychological conditions of patients with chronic respiratory diseases through self-management interventions.

Objective

The aim of this study was to perform a bibliometric analysis of studies on exercise and COPD published from 2000 to 2021 using VOSviewer and CiteSpace.

Methods

All included literature was obtained from the Web of Science core collection. VOSviewer was used to analyze country or region, institution, major co-cited journals, and keywords. CiteSpace was used to analyze centrality, author and co-cited authors, journals, the strongest citation bursts of references, and keywords.

Results

A total of 1889 articles meeting the criteria were obtained. The United States has the largest number of publications. The American Journal of Respiratory and Critical Care Medicine is the most influential in this field, and the most published research institution is Queen's University. Denis E. O'Donnell has made significant contributions to exercise and COPD research. Association, impact, and statement are hot spots of research in this field.

Conclusion

A bibliometric analysis of exercise interventions for COPD over the past 22 years provides direction for future research.

The minimal important difference of the constant work rate cycle test in severe COPD

BACKGROUND

The Constant Work Rate Cycle Test (CWRT) is a commonly used and sensitive test to detect treatment success in patients with Chronic Obstructive Pulmonary Disease (COPD). Earlier, the Minimal Important Difference (MID) of the CWRT was estimated at 101 s (or 34%) change from baseline based on one well executed study. However, this study was performed in a population of patients with mild-to-moderate COPD, and we have learned that MIDs might be quite different in patients with severe COPD. Therefore, we aimed to establish the MID of the CWRT in patients with severe COPD.

METHODS

We included 141 patients with severe COPD, who underwent either pulmonary rehabilitation, bronchoscopic lung volume reduction with endobronchial valves, or a sham bronchoscopy as a control group. CWRT workload was set at 75% of the peak work capacity, as determined by an incremental cycle test. We used the change in 6-min walking test (6-MWT), forced expiratory volume in 1s (FEV₁), residual volume (RV), and St. George's Respiratory Questionnaire (SGRQ) total score as anchors to calculate the MID.

RESULTS

All anchors had an association of ≥0.41 with change in CWRT. The MID estimates for the different anchors were: 6-MWT 278 s (95%), FEV₁ 273 s (90%), RV 240 s (84%), and SGRQ 208 s (71%). The average of these four MID estimates resulted in an MID of 250 s (or 85%).

CONCLUSION

We established the MID for CWRT at 250 s (or 85%) change from baseline in patients with severe COPD.

Impact of bronchoscopic lung volume reduction with endobronchial valves on dynamic hyperinflation: Results from the PIERCE study

BACKGROUND AND OBJECTIVE

Dynamic hyperinflation (DH) is a major marker of exertional dyspnoea in severe emphysema. We hypothesized that bronchoscopic lung volume reduction (BLVR) using endobronchial valves (EBVs) decreases DH.

METHODS

In this prospective bi-centre study from both Toulouse and Limoges Hospitals, we assessed DH during an incremental cycle ergometry before and 3 months after EBVs treatment. The primary objective was to observe the change in inspiratory capacity (IC) at isotime. Target lobe volume reduction (TLVR) and changes in residual volume (RV), forced expiratory volume in one-second (FEV₁ ), mMRC, 6 minutes walking distance (6MWD), BODE and other dynamic measures like tele-expiratory volume (EELV) were also analysed.

RESULTS

Thirty-nine patients were included, of whom thirty-eight presented DH. IC and EELV at isotime significantly improved (+214 mL, p = 0.004; -713 mL, p ˂ 0.001, respectively). Mean changes were +177 mL for FEV₁ (+19%, p < 0.001), -600 mL for RV (p < 0.0001), +33 m for 6MWD (p < 0.0001), respectively. Patients who responded on RV (>430 mL decrease) and FEV₁ (>12% gain) had better improvements compared to non-responders (+368 mL vs. +2 mL; +398 mL vs. -40 mL IC isotime, respectively). On the opposite, in patients who responded on DH (>200 mL IC isotime increase), changes in TLV (-1216 mL vs. -576 mL), FEV₁ (+261 mL vs. +101 mL), FVC (+496 mL vs. +128 mL) and RV (-805 mL vs. -418 mL) were greater compared to non-responders.

CONCLUSIONS

DH decreases after EBVs treatment, and this improvement is correlated with static changes.

Prognostic value of cardiopulmonary exercise testing in a European cohort with cardiovascular risk factors absent of a cardiovascular disease diagnosis

INTRODUCTION

Cardiorespiratory fitness (CRF) is now considered a vital sign. Cardiopulmonary exercise testing (CPET) is the gold-standard assessment of CRF; peak oxygen consumption (VO₂) and the minute ventilation/carbon dioxide production (VE/VCO₂) slope are considered primary CPET measures of CRF. More work is needed to determine the role of this exercise assessment in the primary care setting.

METHODS

695 subjects (mean age: 62 ± 13 years, body mass index: 28.9 ± 5.3 kg/m², 375 female and 320 male) underwent CPET using a cycle ergometer. 95% of the cohort had one or more major cardiovascular risk factor (i.e., obesity, smoking, dyslipidemia, hypertension, diabetes); no subject was diagnosed with cardiovascular disease (CVD) at the time of CPET. Subjects were tracked for the composite endpoint of cardiovascular mortality or hospital admission.

RESULTS

Mean peak VO₂, VE/VCO₂ slope and peak respiratory exchange ratio were 17.8 ± 5.8 mlO₂•kg^-1•min^-1, 26.7 ± 4.1, and 1.18 ± 0.13, respectively. There were 42 composite events during the 64 ± 18 month tracking period. Both peak VO₂ (Chi-square 16.3, p < 0.001) and the VE/VCO₂ slope (Chi-square 14.9, p < 0.001) were significant univariate predictors of the composite endpoint. The VE/VCO₂ slope added significant predictive value to peak VO₂ and was retained in the multivariate regression (residual Chi-square 7.0, p = 0.008).

DISCUSSION

These results support the prognostic value of CPET prior to a CVD diagnosis. The prognostic value of the VE/VCO₂ slope, not commonly the focus of CPET trials in patients with one or more major cardiovascular risk factors but without a confirmed CVD diagnosis, is a particularly novel finding in the current study.

Eight weeks of inorganic nitrate/nitrite supplementation improves aerobic exercise capacity and the gas exchange threshold in patients with type 2 diabetes

Patients with type 2 diabetes mellitus (T2DM) have reduced exercise capacity, indexed by lower maximal oxygen consumption (V̇o2max) and achievement of the gas exchange threshold (GET) at a lower % V̇o2max. The ubiquitous signaling molecule nitric oxide (NO) plays a multifaceted role during exercise and, as patients with T2DM have poor endogenous NO production, we investigated if inorganic nitrate/nitrite supplementation (an exogenous source of NO) improves exercise capacity in patients with T2DM. Thirty-six patients with T2DM (10F, 59 ± 9 yr, 32.0 ± 5.1 kg/m2, HbA1c = 7.4 ± 1.4%) consumed beetroot juice containing either inorganic nitrate/nitrite (4.03 mmol/0.29 mmol) or a placebo (0.8 mmol/0.00 mmol) for 8 wk. A maximal exercise test was completed before and after both interventions. V̇o2max was determined by averaging 15-s data, whereas the GET was identified using the V-slope method and breath-by-breath data. Inorganic nitrate/nitrite increased both absolute (1.96 ± 0.67 to 2.07 ± 0.75 L/min) and relative (20.7 ± 7.0 to 21.9 ± 7.4 mL/kg/min, P < 0.05 for both) V̇o2max, whereas no changes were observed following placebo (1.94 ± 0.40 to 1.90 ± 0.39 L/min, P = 0.33; 20.0 ± 4.2 to 19.7 ± 4.6 mL/kg/min, P = 0.39). Maximal workload was also increased following inorganic nitrate/nitrite supplementation (134 ± 47 to 140 ± 51 W, P < 0.05) but not placebo (138 ± 32 to 138 ± 32 W, P = 0.98). V̇o2 at the GET (1.11 ± 0.27 to 1.27 ± 0.38L/min) and the %V̇o2max in which GET occurred (56 ± 8 to 61 ± 7%, P < 0.05 for both) increased following inorganic nitrate/nitrite supplementation but not placebo (1.10 ± 0.23 to 1.08 ± 0.21 L/min, P = 0.60; 57 ± 9 to 57 ± 8%, P = 0.90) although the workload at GET did not achieve statistical significance (group-by-time P = 0.06). Combined inorganic nitrate/nitrite consumption improves exercise capacity, maximal workload, and promotes a rightward shift in the GET in patients with T2DM. This manuscript reports data from a registered Clinical Trial at ClinicalTrials.gov ID: NCT02804932.NEW & NOTEWORTHY We report that increasing nitric oxide bioavailability via 8 wk of inorganic nitrate/nitrite supplementation improves maximal aerobic exercise capacity in patients with type 2 diabetes mellitus. Similarly, we observed a rightward shift in the gas exchange threshold. Taken together, these data indicate inorganic nitrate/nitrite may serve as a means to improve fitness in patients with type 2 diabetes mellitus.

Tests to uncover and assess breathlessness: a proposed framework

PURPOSE OF REVIEW

Breathlessness is a common, distressing, and limiting symptom that many people avoid by reducing their activity. This review discusses exertional tests that can be used for uncovering and assessing breathlessness depending on the person's severity of illness, function, the setting, and aim of the assessment.

RECENT FINDINGS

Standardized exertional tests are useful to uncover 'hidden' breathlessness earlier in people who may have adapted their physical activity to limit their breathing discomfort. In 'more fit' ambulatory people and outpatients, cardiopulmonary exercise testing is the gold standard for assessing symptom severity, underlying conditions, and mechanisms and treatment effects. Among field tests, the 6-min walk test is not useful for assessing breathlessness. Instead, the 3-min step test and walk test are validated for measuring breathlessness change in chronic obstructive pulmonary disease. In people with more severe illness (who are most often not breathless at rest), reported tests include upper limb exercise or counting numbers aloud, but a valid and useful test for this population is lacking.

SUMMARY

A framework for selecting the most appropriate test to assess breathlessness validly is proposed, and research needs are identified.

The Arabic version of the Lower Extremity Functional Scale is a reliable and valid measure of activity limitation in people with chronic obstructive pulmonary disease

PURPOSE

To examine the psychometric properties of the Arabic version of the Lower Extremity Functional Scale (LEFS-Ar) in people with chronic obstructive pulmonary disease (COPD).

MATERIALS AND METHODS

Stable individuals with COPD (N = 70) confirmed by spirometry were asked to complete the LEFS-Ar, St George's Respiratory Questionnaire (SGRQ) and performed the Six-Minute Walk Test (6MWT). Participants were also asked to complete LEFS-Ar for the second time within 10 days. The LEFS-Ar floor and ceiling effects, internal consistency, test-retest reliability, measurement error, and construct validity were examined.

RESULTS

The LEFS-Ar had excellent internal consistency with Cronbach's alpha of 0.95 and excellent test-retest reliability (ICC_agreement=0.91) with no floor and ceiling issues. Standard error of measurement was 4.78 points while the minimal detectable change at 90% confidence was 11.15 points. Consistent with our hypotheses, the LEFS-Ar scores correlated significantly with 6MWT (r= -0.66, p < 0.001), activity domain of the SGRQ (r = 0.55, p < 0.001), and were significantly different according to COPD disease severity (p= 0.02).

CONCLUSIONS

In people with COPD, the LEFS-Ar has excellent reliability with no floor or ceiling effects. The LEFS-Ar demonstrated evidence supporting its validity as a measure of activity limitation that can be used in clinical practice and in research studies.Implications for rehabilitationThe Arabic version of the Lower Extremity Functional Scale (LEFS-Ar) is a reliable measure in people with chronic obstructive pulmonary disease (COPD).Rehabilitation specialists can use the LEFS-Ar to validly measure activity limitation in people with COPD.

The effect of a pressure ventilatory support on quadriceps endurance is maintained after exercise training in severe COPD patients. A longitudinal randomized, cross over study

Purpose: In severe chronic obstructive pulmonary disease (COPD) patients, the application of an inspiratory pressure support (IPS) during exercise increases exercise tolerance and the benefit of exercise training during pulmonary rehabilitation (PR). Moreover, it improves quadriceps endurance after a session of cycling exercise suggesting a reduced muscle fatigue. We looked for the persistence of this effect after PR and sought an association between the improved quadriceps endurance with IPS and the training load during PR.

Patients and methods: We studied 20 patients with severe COPD (6 in stage 3and 14 in stage 4 of GOLD) before and after PR. As part of a PR program, patients completed 16 cycling sessions over 6 weeks with the addition of IPS during exercise. As a surrogate of muscular fatigue, quadriceps endurance was measured at 70% of maximal strength in a control condition, after a constant work rate exercise test (CWR) with IPS (TlimQ IPS) or with a sham ventilation (TlimQsham), in a random order. These tests were repeated similarly at the end of PR.

Results: PR was associated with a significant increase in maximal power output, cycling endurance, quadriceps strength and endurance. Session training load (power output x duration of the session) increased by 142% during the course of the program. Before PR, CWR duration increases with IPS compared to sham ventilation (Δtime = +244s, p = 0.001). Compared to control condition, post-exercise TlimQ reduction was lower with IPS at isotime than at the end of CWR or than with sham ventilation (−9 ± 21%, −18 ± 16% and −23 ± 18%, respectively, p = 0.09, p &lt; 0.0001 and p &lt; 0.0001). After PR, the post-exercise decrease of TlimQ was reduced after IPS compared to sham (−9 ± 18% vs. −21 ± 17%, respectively, p = 0.004). No relationship was found between the prevention of quadriceps fatigue and the training load.

Conclusion: In severe COPD patients, the beneficial effect of a ventilator support on quadriceps endurance persisted after PR with IPS. However, it was not related to the increase in training load, and could not predict the training response to non-invasive ventilation during exercise.

Intravenous Iron Replacement Improves Exercise Tolerance in COPD: A Single-Blind Randomized Trial

INTRODUCTION

Iron deficiency affects exercise capacity because of the critical role iron plays in the optimal functioning of skeletal muscle metabolism. We hypothesized that intravenous iron may improve exercise tolerance, quality of life (QoL), and daily physical activity (DPA) in patients with chronic obstructive pulmonary disease (COPD).

METHODS

This was a placebo-controlled, single-blind, parallel-group, randomized clinical trial. Iron deficiency was defined as a ferritin level<100ng/mL or a ferritin level between 100 and 299ng/mL with a transferrin saturation<20%, with or without mild anaemia. Patients were randomized at a 2:1 ratio to receive intravenous ferric carboxymaltose or placebo. The primary objective was to investigate whether intravenous iron replacement improved endurance time from baseline by at least 33%. The secondary objectives were to evaluate impact on QoL using the COPD Assessment Test (CAT) and on DPA by accelerometry.

RESULTS

We included 66 patients, 44 (66.7%) in the intervention group and 22 (33.3%) in the placebo group. Among patients receiving ferric carboxymaltose, 23 (52.3%) achieved the primary endpoint compared to 4 (18.2%) in the placebo group [p=0.009; relative risk 3.12, (95% CI, 1.19-8.12)]. CAT score decreased -3 (-6.0-1.3) points from baseline in the intervention group (p=0.007), in contrast to placebo group [-1 (-4.0-2.3) points, p=0.236] with no differences in DPA and adverse events in both groups.

CONCLUSIONS

Iron replacement improved exercise capacity and QoL in stable COPD patients with iron deficiency. The treatment was well tolerated.

CLINICAL TRIAL REGISTRATION

EudraCT 2016-001238-89.

Right Ventricular Contractile Reserve: A Key Metric to Identifying when Cardiorespiratory Fitness will Improve with Pulmonary Vasodilators

Cardiorespiratory fitness (CRF) has been proposed as a vital sign for the past several years, supported by a wealth of evidence demonstrating its significance as a predictor of health trajectory, exercise/functional capacity, and quality of life. According to the Fick equation, oxygen consumption (VO₂) is the product of cardiac output (CO) and arterial-venous oxygen difference, with the former being a primary driver of one's aerobic capacity. In terms of the dependence of aerobic capacity on a robust augmentation of CO from rest to maximal exercise, left ventricular (LV) CO has been the historic focal point. Patients with pulmonary arterial hypertension (PAH) or secondary pulmonary hypertension (PH) present with a significantly compromised CRF; as pathophysiology worsens, so too does CRF. Interventions to improve pulmonary hemodynamics continue to emerge and are now a standard of clinical care in several patient populations with increased pulmonary pressures; new pharmacologic options continue to be explored. Improvement in CRF/aerobic capacity has been and continues to be a primary or leading secondary endpoint in clinical trials examining the effectiveness of pulmonary vasodilators. A central premise for including CRF/aerobic capacity as an endpoint is that pulmonary vasodilation will lead to a significant downstream increase in LV CO and therefore peak VO₂. However, the importance of right ventricular (RV) CO to the peak VO₂ response continues to be overlooked. The current review provides an overview of relevant principles of exercise physiology, approaches to assessing RV contractile reserve and proposals for clinical trial design and subject phenotyping.

Technologies for the Instrumental Evaluation of Physical Function in Persons Affected by Chronic Obstructive Pulmonary Disease: A Systematic Review

Several systems, sensors, and devices are now available for the instrumental evaluation of physical function in persons with Chronic Obstructive Pulmonary Disease (COPD). We aimed to systematically review the literature about such technologies. The literature search was conducted in all major scientific databases, including articles published between January 2001 and April 2022. Studies reporting measures derived from the instrumental assessment of physical function in individuals with COPD were included and were divided into application and validation studies. The quality of validation studies was assessed with the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) risk of bias tool. From 8752 articles retrieved, 21 application and 4 validation studies were included in the systematic review. Most application studies employed accelerometers, gait analysis systems, instrumented mattresses, or force plates to evaluate walking. Surface electro-myography or near-infrared spectroscopy were employed in four studies. Validation studies were heterogeneous and presented a risk of bias ranging from inadequate to doubtful. A variety of data regarding physical function can be retrieved from technologies used in COPD studies. However, a general lack of standardization and limitations in study design and sample size hinder the implementation of the instrumental evaluation of function in clinical practice.

Effectiveness of Outpatient Pulmonary Rehabilitation in Patients with Surgically Resected Lung Cancer: A Retrospective Real-World Analysis

Patients with lung cancer frequently suffer from physical deconditioning, low exercise capacity, and reduced quality of life. There is little evidence on the effects of a structured outpatient pulmonary rehabilitation program (OPR) on exercise capacity and symptom load in these patients. We performed a retrospective, single-center analysis of surgically resected lung cancer patients, who underwent a multiprofessional 6-week OPR. The primary endpoint was a change in the six-minute walk test distance (6 MWT). Secondary endpoints included changes in maximal workload and constant work-rate test results during cycle-ergometry, upper and lower extremity strength, and inspiratory muscle strength. The COPD Assessment Test (CAT) was used to assess symptom burden. Fifty-seven patients were included. Of those, fifty-two (91.2%) completed the full 6 weeks of OPR. The mean age was 56.4 (SD 9.2) years, and 58% were female. At completion of OPR, there was a statistically significant mean of a 50 m (95% CI, 29.6−70.7; p < 0.001) increase in 6 MWT. Significant improvements were also seen in all other exercise and strength tests (p < 0.001), accompanied by a significant reduction in the CAT score (mean difference −3.1, p = 0.001). No adverse effects were reported. OPR for surgically resected lung cancer patients was safe and effective and showed high adherence in the current study.

Evaluation of maximal exercise capacity through the incremental shuttle walking test in lymphangioleiomyomatosis

BACKGROUND

The cardiopulmonary exercise test (CPET) is the gold standard for assessing aerobic fitness; however, it is expensive, not widely available, and requires specialized equipment and staff. The incremental shuttle walking test (ISWT) is an exercise field test used to evaluate exercise capacity and may be an alternative to CPET in patients with lymphangioleiomyomatosis (LAM).

OBJECTIVE

To investigate whether the ISWT can be used to assess maximal aerobic capacity in patients with LAM.

METHODS

Forty-five women were evaluated on two days, and they randomly performed the CPET and ISWT. The maximum oxygen uptake (peak VO2) was evaluated using gas analyzers in both tests. The carbon dioxide production (VCO2), respiratory exchange ratio (RER), and heart rate (HR) were compared during peak exercise. Pearson's correlation and Bland-Altman assessed the association and agreement, respectively. The intraclass correlation coefficient (ICC) was used to assess the reliability of the data.

RESULTS

All patients (46.1 ± 10.2 years) presented similar peak VO2, RER, and peak HR during the CPET and ISWT (15.6 ± 4.6 vs. 15.7 ± 4.4 ml·kg-1·min-1; 1.15±0.09 vs. 1.17±0.12; and 142.2 ± 18.6 vs. 141.5 ± 22.2 bpm, respectively; p>0.05). A good linear correlation (r = 0.79; p<0.001) and ICC (0.86; 95%CI 0.74-0.93) were observed between the peak VO2 in both tests. Predictive peak VO2 equations based on the ISWT performance are also presented.

CONCLUSION

Our results suggest that the ISWT can be used to assess maximal exercise performance in patients with LAM, and it is a valuable option to be used as an alternative to the CPET and predict maximal exercise capacity.

Using Cardiopulmonary Exercise Testing to Understand Dyspnea and Exercise Intolerance in Respiratory Disease

A cardiopulmonary exercise test (CPET) is ideally suited to quantify exercise tolerance and evaluate the pathophysiological mechanism(s) of dyspnea and exercise limitation in people with chronic respiratory disease. Although there are several statements on CPET and many outstanding resources detailing the cardiorespiratory and perceptual responses to exercise, limited information is available to support the health care provider in conducting a practical CPET evaluation. This article provides the health care provider with practical and timely information on how to use CPET data to understand dyspnea and exercise intolerance in people with chronic respiratory diseases. Information on CPET protocol, as well as how to evaluate maximal patient effort, peak rate of oxygen consumption, ventilatory demand, pulmonary gas exchange, ventilatory reserve, operating lung volumes, and exertional dyspnea, is presented. Two case examples are also described to highlight how these parameters are evaluated to provide a clinical interpretation of CPET data.

Reply to "Six-minute walking test performance is associated with survival in cirrhotic patients" to the editor

Use of the six-minute walk test has been proposed as a prognostic marker in liver cirrhosis. In the Letter to the Editor presented here, the authors highlight some important points, which were raised after the article was published in the November issue of the World Journal of Hepatology.

Respiratory responses to hypoxia during rest and exercise in individuals born pre-term: a state-of-the-art review

The pre-term birth survival rate has increased considerably in recent decades, and research investigating the long-term effects of premature birth is growing. Moreover, altitude sojourns are increasing in popularity and are often accompanied by various levels of physical activity. Individuals born pre-term appear to exhibit altered acute ventilatory responses to hypoxia, potentially predisposing them to high-altitude illness. These impairments are likely due to the use of perinatal hyperoxia stunting the maturation of carotid body chemoreceptors, but may also be attributed to limited lung diffusion capacity and/or gas exchange inefficiency. Aerobic exercise capacity also appears to be reduced in this population. This may relate to the aforementioned respiratory impairments, or could be due to physiological limitations in pulmonary blood flow or at the exercising muscle (e.g. mitochondrial efficiency). However, surprisingly, the debilitative effects of exercise when performed at altitude do not seem to be exacerbated by premature birth. In fact, it is reasonable to speculate that pre-term birth could protect against the consequences of exercise combined with hypoxia. The mechanisms that underlie this assertion might relate to differences in oxidative stress responses or in cardiopulmonary morphology in pre-term individuals, compared to their full-term counterparts. Further research is required to elucidate the independent effects of neonatal treatment, sex differences and chronic lung disease, and to establish causality in some of the proposed mechanisms that could underlie the differences discussed throughout this review. A more in-depth understanding of the acclimatisation responses to chronic altitude exposures would also help to inform appropriate interventions in this clinical population.