Perceptual and physiologic responses during treadmill and cycle exercise in patients with COPD

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.

Effect of neuromuscular electrical stimulation on exercise capacity in patients with severe chronic obstructive pulmonary disease: A randomised controlled trial

OBJECTIVE

To compare strengthening by neuromuscular electrical stimulation versus cycle ergometer training during a pulmonary rehabilitation program, in patients with severe to very severe chronic obstructive pulmonary disease.

DESIGN

A prospective randomized controlled study.

SETTING

Two inpatient pulmonary rehabilitation centers.

SUBJECTS

Patients with severe to very severe chronic obstructive pulmonary disease and multidimensional index to predict risk of death ≥5, were randomly assigned to receive neuromuscular electrical stimulation or cycle ergometer training during pulmonary rehabilitation.

MAIN MEASURES

The primary endpoint was the change in exercise capacity using 1-min sit-to-stand test Secondary endpoints were the changes in exercise capacity using 6-min walk test, quadriceps strength, quality of life and dyspnea.

RESULTS

102 patients were included. After 3 weeks, 47 patients in the neuromuscular electrical stimulation group, and 45 in the cycle ergometer training group were able to be analyzed. No significant difference was seen in the evolution of exercise capacity using 1-min sit-to-stand test (3.3 ± 3.8 and 2.6 ± 4.1) and 6-min walk test (37.8 ± 58.4 and 33.1 ± 46.7), in the evolution of quadriceps strength and endurance (9.2 ± 12.9 and 6.6 ± 16.1; 9.0 ± 13.2 and 6.2 ± 17.0), in the evolution of quality of life (St George's Respiratory Questionnaire: -11.3 ± 11.7 and -8.1 ± 11.6; COPD Assessment Test: -5.7 ± 7.1 and -4.7 ± 7.0), or in the evolution of dyspnea using Dyspnea 12 (-5.5 ± 10.2 and -5.9 ± 8.5) except using modified medical research council scale (95% confidence interval: 0.48 [0.05; 0.91], p = 0.027).

CONCLUSION

We found no significant difference between the two programs on exercise capacity, quadriceps strength and quality of life.

ERS statement on standardisation of cardiopulmonary exercise testing in chronic lung diseases

The objective of this document was to standardise published cardiopulmonary exercise testing (CPET) protocols for improved interpretation in clinical settings and multicentre research projects. This document: 1) summarises the protocols and procedures used in published studies focusing on incremental CPET in chronic lung conditions; 2) presents standard incremental protocols for CPET on a stationary cycle ergometer and a treadmill; and 3) provides patients' perspectives on CPET obtained through an online survey supported by the European Lung Foundation. We systematically reviewed published studies obtained from EMBASE, Medline, Scopus, Web of Science and the Cochrane Library from inception to January 2017. Of 7914 identified studies, 595 studies with 26 523 subjects were included. The literature supports a test protocol with a resting phase lasting at least 3 min, a 3-min unloaded phase, and an 8- to 12-min incremental phase with work rate increased linearly at least every minute, followed by a recovery phase of at least 2–3 min. Patients responding to the survey (n=295) perceived CPET as highly beneficial for their diagnostic assessment and informed the Task Force consensus. Future research should focus on the individualised estimation of optimal work rate increments across different lung diseases, and the collection of robust normative data.

The document facilitates standardisation of conducting, reporting and interpreting cardiopulmonary exercise tests in chronic lung diseases for comparison of reference data, multi-centre studies and assessment of interventional efficacy.http://bit.ly/31SXeB5

Incremental step test in patients with pulmonary hypertension

Cardiopulmonary exercise testing (CPET) on a treadmill or cycle ergometer provides an integrated assessment of the cardiorespiratory system during exertion and is widely used in clinical practice. An incremental step test (IST) can be an alternative for eliciting maximal exercise responses. Therefore, 20 patients with pre-capillary PH (65% female, 41 ± 15 yrs) randomly performed a symptom-limited CPET on a cycle ergometer and IST. Metabolic, cardiovascular, ventilatory and gas exchange variables were recorded during both tests. There was a greater desaturation and higher V̇O_2PEAK in IST compared to CPET. The V̇O_2GET, HR _PEAK (% pred), ΔV̇E/ΔV̇CO₂ and ΔHR/ΔV̇O₂ were similar in both IST and CPET. By linear regression analyses, the work performed on IST [W = (mass × 9,8 m/s2 x vertical distance)] was a predictor of peak V̇O₂ independent of the gender and age (r² = 077, p = 0001). In conclusion, IST elicited higher peak cardiopulmonary responses and has a good agreement with known severity markers in patients with pre-capillary PH.

[Follow-up and evaluation of plans developed during pulmonary rehabilitation]

BACKGROUND

Pulmonary rehabilitation inevitably contains two essential components: therapeutic education and exercise training. The principal aim of this study was to evaluate the evolution over a year of the realization of plans determined during a pulmonary rehabilitation program (PRP).

METHODS

At the end of a PRP the patient made plans in accordance with his health condition. A telephone enquiry was undertaken at 3, 7 and 12 months to evaluate the progress of the plans, the motivation to perform them, dyspnoea and quality of life.

RESULTS

The data of 65 patients were analyzed (87 inclusions). Fifty-seven percent of the plans continued for one year. Walking had an adherence rating of 71%. Loss of motivation appeared to be the main cause for stopping (20%). Quality of life remained stable (p=0.39) and an increase in dyspnoea, though statistically significant (p<0.01), was of no clinical relevance.

CONCLUSION

The majority of plans were maintained but without clinical effect on the quality of life or the level of dyspnoea. Decreased motivation was the major limitation to realization or continuation of the plans. New studies will have to be implemented to analyze the factors which lead to this decrease.

Cardiorespiratory Response to Different Exercise Tests in Interstitial Lung Disease

INTRODUCTION

The 6-min stepper test (6MST) has been used as an alternative to the 6-min walk test (6MWT) to assess exercise tolerance in patients with interstitial lung disease (ILD). Recent data suggest that the tests may involve different energy pathways and cardiorespiratory responses. We thus aimed to compare the cardiorespiratory responses of ILD patients during the 6MWT and the 6MST.

METHODS

Thirty-one patients with ILD were randomized to perform both tests in the order 6MST → 6MWT (n = 16) or 6MWT → 6MST (n = 15). Gas exchange, HR, and pulse O2 saturation (SpO2) were measured continuously, and dyspnoea, leg discomfort, and blood lactate concentration were assessed before and immediately after each test.

RESULTS

Oxygen uptake (V˙O2) was lower (P = 0.002) and respiratory equivalent ratio for O2 (V˙E/V˙O2) and RER were higher (both P < 0.001) during the 6MST compared with the 6MWT. The 6MST was also associated with higher blood lactate concentrations (6MST, 4.16 ± 1.95 mmol·L; 6MWT, 2.84 ± 1.17 mmol·L; P = 0.01), higher leg discomfort scores (6MST 5 ± 3 points, 6MWT 3 ± 2 points; P < 0.001), and smaller decreases in SpO2 (6MST -5% ± 5%, 6MWT -9% ± 6%; P < 0.001).

CONCLUSIONS

ILD patients exhibited greater ventilatory responses and lower arterial O2 desaturation during the 6MST compared with the 6MWT. The higher lactate concentrations and perceived muscle fatigue observed during the 6MST may indicate the presence of intertest differences in active muscle metabolism that could contribute to the distinct cardiorespiratory responses.

Comparing Various Exercise Tests for Assessing the Response to Pulmonary Rehabilitation in Patients With COPD

PURPOSE

Various exercise tests have been used to assess the response to pulmonary rehabilitation (PR) in patients with chronic obstructive pulmonary disease (COPD). Few studies have compared exercise tests in the same subjects to determine the relative responsiveness of various tests. The goal of this pilot study was to examine the responsiveness of different exercise tests in patients with COPD completing PR.

METHODS

Fifteen male patients with COPD underwent PR. All subjects completed 6-minute walk test (6MWT), incremental shuttle walk test (ISWT), endurance shuttle walk test (ESWT), maximal incremental exercise test (MIET), constant workload exercise test (CWET), and maximal arm ergometry tests before and after PR. The Chronic Respiratory Disease Questionnaire was also completed before and after PR.

RESULTS

The number of participants who exceeded the minimal clinically important difference was similar for each of the different exercise tests. Effect sizes for the MIET and CWET were slightly higher, 0.82 and 0.97, respectively, than for the 6MWT, ISWT, and ESWT, 0.72, 0.65, and 0.60, respectively. Effect sizes were not significantly different between the 6MWT and the ESWT. The changes in exercise test results were not significantly correlated with the changes in quality of life. The improvement in laboratory cycling tests did not significantly correlate with the improvement in shuttle walk tests.

CONCLUSIONS

On the basis of these data, all exercise measures were responsive to PR. Indices derived from cycling in the laboratory appeared more responsive than indices derived from walking in the field when assessed by effect size, but this finding and its possible clinical significance requires confirmation in a larger study.

Is the six-minute walk test a useful tool to prescribe high-intensity exercise in patients with chronic obstructive pulmonary disease?

BACKGROUND

It is not yet completely known whether the 6MWT can be used to prescribe high-intensity exercise for patients with COPD.

OBJECTIVE

To evaluate the ability of the six-minute walk test (6MWT) to prescribe high-intensity exercise for patients with chronic obstructive pulmonary disease (COPD).

METHODS

Lung function, maximal inspiratory strength, symptoms and exercise capacity were evaluated in patients with COPD (n = 27) before and after a 12-week high-intensity exercise program. Criteria for high-intensity training were: 1) ≥75% of the 6MWT average speed; 2) American Thoracic Society/European Respiratory Society (ATS/ERS) criteria (≥60% of the maximal incremental shuttle walk test speed).

RESULTS

The 6MWT showed good positive and negative predictive values (0.69 and 0.71, respectively), and accuracy (0.70), good reliability (ICC 0.70 [95%CI 0.45-0.85]) and moderate agreement (k 0.41 [95%CI 0.13-0.67]) with the ATS/ERS criteria.

CONCLUSION

The 6MWT has good predictive ability and accuracy in relation to high-intensity exercise for patients with COPD.

Effect of combination treatment on lung volumes and exercise endurance time in COPD

BACKGROUND

Data comparing two bronchodilators vs. one bronchodilator plus inhaled corticosteroid (ICS) on hyperinflation and exercise endurance in chronic obstructive pulmonary disease (COPD) are scarce, though these therapeutic strategies are widely used in clinical practice.

METHODS

We performed a randomized, crossover clinical trial of two × 8 weeks comparing tiotropium (18 μg once daily) + salmeterol (50 μg twice daily) (T + S) to salmeterol + fluticasone (50/500 μg twice daily) (S + F) in COPD (forced expiratory volume in 1 s (FEV(1)) ≤65% predicted, and thoracic gas volume (TGV) ≥120% predicted). Coprimary endpoints were postbronchodilator TGV and exercise endurance time (EET).

RESULTS

In 309 patients, at baseline, prebronchodilator FEV(1) was 1.36 L (46% predicted), TGV was 5.42 L (165% predicted), and EET = 458 s. Relative to S + F, T + S lowered postdose TGV by 182 ± 44 ml after 4 weeks (p < 0.0001) and 87 ± 44 ml after 8 weeks (p < 0.05). EET was nonsignificantly increased following T + S treatment (20 ± 15 s at 4 weeks, 15 ± 13 s at 8 weeks) vs. S + F. BORG dyspnea score at exercise isotime was reduced in favor of T + S.

CONCLUSION

The two bronchodilators decreased hyperinflation significantly more than one bronchodilator and ICS. This difference was not reflected in EET. (ClinicalTrials.gov number, NCT00530842).

Mechanism of greater oxygen desaturation during walking compared with cycling in patients with COPD

BACKGROUND

Patients with COPD exhibit greater oxyhemoglobin desaturation during walking than with cycling. The purpose of this investigation was to investigate differences in ventilatory responses and gas exchange as proposed mechanisms for this observation.

METHODS

Arterial blood gas and lactate levels were measured in 12 patients with COPD (aged 68 ± 6 years) during incremental treadmill and cycle exercise. The primary outcome to assess the ventilatory response to exercise was Pao₂. The primary outcome to assess impairment in exercise gas exchange was the difference between partial pressures of alveolar and arterial oxygen (Pao₂ - Pao₂).

RESULTS

Pao₂ in patients was significantly lower at peak exercise for treadmill walking (51.4 ± 6.8 mm Hg) compared with cycling (60.4 ± 10.7 mm Hg) (P = .002). The initial increase in Pao₂ with cycling occurred prior to the onset of the anaerobic threshold. At peak exercise, Pao₂ was significantly higher with cycling compared with walking (P = .004). The anaerobic threshold occurred at a lower oxygen consumption during cycling than walking (P = .001), and peak lactate levels were higher with cycling (P = .019). With progressive exercise, Pao₂ - Pao₂ increased similarly during treadmill and cycle exercise.

CONCLUSIONS

The higher Pao₂ during cycling minimized the magnitude of oxyhemoglobin desaturation compared with walking. The enhanced respiratory stimulation during cycling appears due to an initial neurogenic process, possibly originating in receptors of exercising muscles, and a subsequent earlier onset of anaerobic metabolism with higher lactate levels during cycling.

Outcome measures in chronic obstructive pulmonary disease (COPD): strengths and limitations

Current methods for assessing clinical outcomes in COPD mainly rely on physiological tests combined with the use of questionnaires. The present review considers commonly used outcome measures such as lung function, health status, exercise capacity and physical activity, dyspnoea, exacerbations, the multi-dimensional BODE score, and mortality. Based on current published data, we provide a concise overview of the principles, strengths and weaknesses, and discuss open questions related to each methodology. Reviewed is the current set of markers for measuring clinically relevant outcomes with particular emphasis on their limitations and opportunities that should be recognized when assessing and interpreting their use in clinical trials of COPD.

Impact of bronchodilator therapy on exercise tolerance in COPD

Exercise tolerance is an important parameter in patients with COPD and a primary goal of treatment is to reduce dyspnea to facilitate physical activities and improve health-related quality of life. This review examines the link between expiratory flow limitation and dyspnea to explain the rationale for the use of bronchodilators and review the characteristics of different types of exercise tests, with specific focus on which tests are likely to show a response to bronchodilators. An earlier literature search of studies published up to 1999 assessed the effects of bronchodilatort therapy on dypsnea and exercise tolerance among patients with COPD. This current review examines the clinical evidence published since 1999. Thirty-one randomized studies of exercise tolerance associated with short- and long-acting beta(2)-agonists and anticholinergics were identified. Evidence for the efficacy of bronchodilators in enhancing exercise capacity is often contradictory and possibly depends on the exercise test and study methodology. However, further studies should confirm the benefit of long-acting bronchodilators in improving spontaneous everyday physical activities.

Advantages of endurance treadmill walking compared with cycling to assess bronchodilator therapy

BACKGROUND

Walking is a familiar daily activity that is generally limited by breathlessness, whereas cycling is an uncommon physical effort typically limited by leg discomfort. The hypothesis was that patients with COPD would exhibit greater improvements in exercise endurance and relief of breathlessness with bronchodilator therapy during treadmill walking compared with cycling.

METHODS

In this randomized, 2 x 2, double-blind, placebo-controlled, crossover trial, 20 patients with COPD (age, 64 +/- 7 years; FEV(1), 56 +/- 14% predicted) performed constant-load endurance exercise on the treadmill and cycle ergometer at 85% of capacity after inhaling normal saline (NS) or arformoterol (ARF) (15 microg).

RESULTS

Increases in endurance times and consistency of responses were greater with treadmill walking (Delta: 157 +/- 286 s; P = .024; 80% improved) than with cycle exercise (Delta: 110 +/- 219 s; P = .038; 65% improved) with ARF compared with NS. However, these changes were not significantly different. The slope of breathlessness-time (mean Delta = -29%; P = .007) and the magnitude of oxygen desaturation were significantly lower with ARF compared with NS during treadmill, but not cycle, exercise. Inspiratory capacity values were similar between modes of exercise when comparing the same study medication.

CONCLUSIONS

Improved endurance times support both constant-load treadmill and cycle exercise to assess the efficacy of bronchodilator therapy in patients with COPD. Unique differences in physiologic and perceptual responses with bronchodilation demonstrate advantages of treadmill walking as an exercise stimulus.

TRIAL REGISTRATION

clinicaltrials.gov; Identifier: NCT00754546.