Comparison of Continuous and Discrete Measurements of Dyspnea During Exercise in Patients With COPD and Normal Subjects

doi:10.1378/chest.125.1.77

Chest

Volume 125, Issue 1, January 2004, Pages 77-84

https://doi.org/10.1378/chest.125.1.77 Get rights and content

Study objectives

The objectives of this study were as follows: (1) to compare results of the discrete and the continuous methods for measuring breathlessness; (2) to examine test-retest reliability; (3) and to test the hypothesis that patients with COPD have higher slopes and lower x-intercepts and absolute thresholds for power production, oxygen consumption (

o₂), and minute ventilation as independent variables and breathlessness ratings as the dependent variable, as compared with healthy subjects.

Design

Visit 1 (familiarization) and visit 2 and visit 3 (2 days apart) with randomized assignment of the discrete and continuous methods for subjects rating breathlessness during cycle ergometry.

Setting

Cardiopulmonary exercise laboratory in a university medical center.

Participants

Twenty-four patients with COPD (mean age, 66 ± 8 years [± SD]) and 24 healthy subjects (mean age, 66 ± 10 years).

Interventions

None.

Measurements and results

Ratings of breathlessness on the Borg scale on cue with subjects moving and pressing the computer mouse button to indicate a rating (discrete method) or by moving the position of the mouse to adjust a vertical bar to indicate a change in breathlessness (continuous method). There were no significant differences in results between visit 2 and visit 3. Although peak exercise variables were similar with the discrete and continuous methods, both groups provided significantly more ratings of breathlessness with the continuous method. Patients with COPD exhibited higher slopes, lower x-intercepts, and lower absolute thresholds (breathlessness rating ≥ 0.5 [“just noticeable”] on the Borg scale) for power production and

o₂-breathlessness compared with healthy subjects (p < 0.05).

Conclusions

Elderly patients with COPD and healthy subjects are able to use the continuous method successfully. Reliability is excellent for both methods. The continuous method provides a greater number of breathlessness ratings over the course of exercise, and allows the clinician to calculate an absolute threshold and just-noticeable differences. Regression parameters and absolute thresholds discriminate between patients with COPD and healthy subjects.

Section snippets

Subjects

Inclusion criteria for all participants were as follows: age ≥ 45 years, ability to exercise on the cycle ergometer, and no history of clinically important comorbid disease. Patients with COPD were recruited from the outpatient clinics of our institution. The diagnosis of COPD was based on American Thoracic Society criteria,⁸ and each patient complained of exertion breathlessness. All healthy subjects were recruited from family members or friends of the patients, they denied any

Results

A total of 49 subjects were enrolled in the study. One patient was withdrawn from the study after visit 2 because she was unable to use the computer system consistently. Table 1 gives the characteristics of the 24 patients with COPD and 24 age-matched healthy subjects who completed the study. The age and gender distribution of the two groups were similar.

Figure 2 represents exercise data for an individual patient with COPD to illustrate the relationships between the physiologic variables and

Discussion

The major findings of this study were as follows: (1) there was excellent test-retest reliability for all of the parameters of interest; (2) the continuous method yielded significantly more ratings during exercise compared with the discrete method, and enabled calculation of an absolute threshold and JNDs; (3) patients with COPD exhibited significantly higher slopes and lower x-intercepts for power production and

o₂ (as independent variables) with breathlessness (as the dependent variable)

Conclusions

The current study extends our previous report⁷ that elderly individuals, both healthy subjects as well as patients with COPD, can successfully use a computer system to provide spontaneous and continuous ratings of breathlessness during exercise. Furthermore, these results highlight several advantages of the continuous method. The continuous method illustrates clearly how the perception of breathlessness changes throughout the entire course of an exercise test rather than only at arbitrary 1-min

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Cited by (37)

Measuring intensity during free-living physical activities in people with chronic obstructive pulmonary disease: A systematic literature review
2022, Annals of Physical and Rehabilitation Medicine
Citation Excerpt :
The Borg scores were used to assess dyspnoea, fatigue and rate of perceived exertion. Borg scales are valid, reliable, quick, user-friendly, and inexpensive tools and thus, widely used in broad free-living settings [18, 64-66]. These instruments have been recommended to prescribe exercise intensity in people with COPD [10] and to assess symptoms during cardiopulmonary exercise test [67].
Measuring intensity of physical activity (PA) is important to ensure safety and the effectiveness of PA interventions in chronic obstructive pulmonary disease (COPD).
This systematic review identified which outcomes, outcome measures and instruments have been used to assess single free-living PA-related intensity in people with COPD and compared the intensity level (light, moderate, vigorous) obtained by different outcome measures.
PubMed, Scopus, Web of Science, Cochrane Library and EBSCO were searched for original studies of COPD and assessing single free-living PA-related intensity were included. Agreement was calculated as the number of agreements between 2 measures [same intensity level]/ number of comparisons using both measures*100.
We included 43 studies (1282 people with COPD, mean age 66 years, 65% men, 49% FEV_1%pred) and identified 13 outcomes, 46 outcome measures and 22 instruments. The most-reported outcomes, outcome measures and instruments were dyspnoea with the Borg scale 0–10; cardiac function, via heart rate (HR) using HR monitors; and pulmonary gas exchange, namely oxygen consumption (VO₂), using portable gas analysers, respectively. The most frequently assessed PAs were walking and lifting, changing or moving weights/objects. Agreement between the outcome measures ranged from 0 (%VO_2peak vs metabolic equivalent of task [MET];%HR_peak vs Fatigue Borg; MET vs walking speed) to 100% (%HR_reserve vs dyspnoea Borg; fatigue and exertion Borg vs walking speed).%VO_{2peak/reserve} elicited the highest intensity. Hence, Borg scores,%HR_reserve and MET may underestimate PA-related intensity.
Various methodologies are used to assess single free-living PA-related intensity and yield different intensity levels for the same PA. Future studies, further exploring the agreement between the different outcome measures of PA-related intensity and discussing their advantages, disadvantages and applicability in real-world settings, are urgent. These would guide future worldwide recommendations on how to assess single free-living PA-related intensity in COPD, which is essential to optimise PA interventions and ensure patient safety.
Evaluation of Dyspnea in the Elderly
2017, Clinics in Geriatric Medicine
Simple artificial training device for respiratory muscle strength and lung volumes in healthy young male and female subjects: A pilot study
2017, Journal of Bodywork and Movement Therapies
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Dyspnea also is used with precautions from any harmful exercise, especially in the COPD clinic. Although this assessment tool is subjective (ATS, 1999), it can be used to represent the intensity of overload during exercise in either patients with COPD or normal subjects (Fierro-Carrion et al., 2004). Moreover, other hemodynamic parameters in this study, such as heart rate (HR), blood pressure (BP), respiratory rate (RR), and % of oxygen saturation also were evaluated at the end of the training day in the last week, as was the peak dyspnea score, which had no statistical difference.
The aim of this study was to evaluate the efficiency of a simple artificial device for respiratory muscle strength training and lung volumes using either combined or non-combined exercise with elastic bands in healthy young participants.
Forty healthy young participants (20 male and 20 female) aged 19–24 years old were randomized into two main experiments with four sub-groups; (1) artificial device (n = 10) & standard device (n = 10) training, and (2) artificial device training combined with elastic band (EB) exercise (n = 10) & standard device training combined with EB (n = 10) exercise. Respiratory muscle strength with maximal peak inspiratory pressure (PImax), and lung volumes; tidal volume (TV), inspiratory reserve volume (IRV), expiratory reserve volume (ERV) and vital capacity (VC) were evaluated before and after training once daily for 3 weeks. Moreover, the peak dyspnea score and vital sign parameters were compared between the experimental groups after final training.
All parameters had no statistical differences (p > 0.5) between the training devices alone and those combined with EB exercise prior to any experiments. Results from the first experiment showed that training with an artificial device increased all parameters (PImax, VC, IRV, ERV) significantly (p < 0.05), except for TV, when compared to pre training results, which were the same as those in the standard device training group. No statistical difference was shown between these groups after the training period had been performed. Furthermore, results of applying artificial device training combined with EB exercise showed a significant increase in all parameters, except for TV, and they were the same as the increased results in training with the standard device combined with EB exercise. There was no significant difference of data between these groups after the training period. Finally, the results of peak dyspnea score and all vital sign parameters from using the artificial device, with or without EB exercise, showed no statistical difference when compared to use of the standard device.
This study proposed that a simple artificial device can be used to train the respiratory muscle with or without elastic band exercise in healthy young subjects.
Practical Dyspnea Assessment: Relationship between the 0-10 Numerical Rating Scale and the Four-Level Categorical Verbal Descriptor Scale of Dyspnea Intensity
2015, Journal of Pain and Symptom Management
Measurement of dyspnea is important for clinical care and research.
To characterize the relationship between the 0–10 Numerical Rating Scale (NRS) and four-level categorical Verbal Descriptor Scale (VDS) for dyspnea assessment.
This was a substudy of a double-blind randomized controlled trial comparing palliative oxygen to room air for relief of refractory breathlessness in patients with life-limiting illness. Dyspnea was assessed with both a 0–10 NRS and a four-level categorical VDS over the one-week trial. NRS and VDS responses were analyzed in cross section and longitudinally. Relationships between NRS and VDS responses were portrayed using descriptive statistics and visual representations.
Two hundred twenty-six participants contributed responses. At baseline, mild and moderate levels of breathlessness were reported by 41.9% and 44.6% of participants, respectively. NRS scores demonstrated increasing mean and median levels for increasing VDS intensity, from a mean (SD) of 0.6 (±1.04) for VDS none category to 8.2 (1.4) for VDS severe category. The Spearman correlation coefficient was strong at 0.78 (P < 0.0001). Based on the distribution of NRS scores within VDS categories, we calculated test characteristics of two different cutpoint models. Both models yielded 75% correct translations from NRS to VDS; however, Model A was more sensitive for moderate or greater dyspnea, with fewer misses downcoded.
There is strong correlation between VDS and NRS measures for dyspnea. Proposed practical cutpoints for the relationship between the dyspnea VDS and NRS are 0 for none, 1–4 for mild, 5–8 for moderate, and 9–10 for severe.
Mechanism of greater oxygen desaturation during walking compared with cycling in patients with COPD
2011, Chest
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.
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).
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.
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.
Effect of palliative oxygen versus room air in relief of breathlessness in patients with refractory dyspnoea: A double-blind, randomised controlled trial
2010, The Lancet
Palliative oxygen therapy is widely used for treatment of dyspnoea in individuals with life-limiting illness who are ineligible for long-term oxygen therapy. We assessed the effectiveness of oxygen compared with room air delivered by nasal cannula for relief of breathlessness in this population of patients.
Adults from outpatient clinics at nine sites in Australia, the USA, and the UK were eligible for enrolment in this double-blind, randomised controlled trial if they had life-limiting illness, refractory dyspnoea, and partial pressure of oxygen in arterial blood (PaO₂) more than 7·3 kPa. Participants were randomly assigned in a 1:1 ratio by a central computer-generated system to receive oxygen or room air via a concentrator through a nasal cannula at 2 L per min for 7 days. Participants were instructed to use the concentrator for at least 15 h per day. The randomisation sequence was stratified by baseline PaO₂ with balanced blocks of four patients. The primary outcome measure was breathlessness (0–10 numerical rating scale [NRS]), measured twice a day (morning and evening). All randomised patients who completed an assessment were included in the primary analysis for that data point (no data were imputed). This study is registered, numbers NCT00327873 and ISRCTN67448752.
239 participants were randomly assigned to treatment (oxygen, n=120; room air, n=119). 112 (93%) patients assigned to receive oxygen and 99 (83%) assigned to receive room air completed all 7 days of assessments. From baseline to day 6, mean morning breathlessness changed by −0·9 points (95% CI −1·3 to −0·5) in patients assigned to receive oxygen and by −0·7 points (−1·2 to −0·2) in patients assigned to receive room air (p=0·504). Mean evening breathlessness changed by −0·3 points (−0·7 to 0·1) in the oxygen group and by −0·5 (−0·9 to −0·1) in the room air group (p=0·554). The frequency of side-effects did not differ between groups. Extreme drowsiness was reported by 12 (10%) of 116 patients assigned to receive oxygen compared with 14 (13%) of 108 patients assigned to receive room air. Two (2%) patients in the oxygen group reported extreme symptoms of nasal irritation compared with seven (6%) in the room air group. One patient reported an extremely troublesome nose bleed (oxygen group).
Since oxygen delivered by a nasal cannula provides no additional symptomatic benefit for relief of refractory dyspnoea in patients with life-limiting illness compared with room air, less burdensome strategies should be considered after brief assessment of the effect of oxygen therapy on the individual patient.
US National Institutes of Health, Australian National Health and Medical Research Council, Duke Institute for Care at the End of Life, and Doris Duke Charitable Foundation.

View all citing articles on Scopus

: Financial support was provided by the National Institutes of Health, Small Business Innovation Grant No. 1 R43 HL68493-01 (Dr. Baird).

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Chest

Clinical InvestigationsCOPDComparison of Continuous and Discrete Measurements of Dyspnea During Exercise in Patients With COPD and Normal Subjects

Study objectives

Design

Setting

Participants

Interventions

Measurements and results

Conclusions

Section snippets

Subjects

Results

Discussion

Conclusions

Chest

Br J Dis Chest

Chest

Chest

Chest

Fundamentals of scaling and psychophysics

Dyspnea and leg effort during incremental cycle ergometry

Am Rev Respir Dis

Clinical Investigations
COPD
Comparison of Continuous and Discrete Measurements of Dyspnea During Exercise in Patients With COPD and Normal Subjects