Papers in the journal Chronic Respiratory Disease (Page 25) | Read by QxMD
Although the change in end-exercise total chest wall volume under an equivalent workload was no different after PR in the improver group or in the non-improver group Figures 2A and 2B , respectively , a significant post-PR decrease in rib cage operating volume was seen in the former and not in the latter Figures 2C and 2D , respectively. In addition, the end-expiratory volume of the abdominal compartment during submaximal exercise was higher in the improvers than in the non-improvers Figures 2E and 2F , respectively , although the difference did not reach statistical significance.
We saw the same changes in end-expiratory lung volume when the response to rehabilitation was categorized by the ability to increase walking distance by 30 m or more, a recently proposed minimum clinically important difference. Figure 2. Comparison between COPD patients who improved after pulmonary rehabilitation PR and those who did not, in terms of pre- and post-PR changes in the inspiratory operating volume of the chest wall A and B , rib cage C and D , and abdomen E and F during incremental exercise at an equivalent workload, defined as the percentage of the maximum workload achieved during the pre-PR incremental exercise test.
Most patients with COPD report reduced exercise tolerance and show varying degrees of dynamic hyperinflation during exercise. In addition, some of our subjects continued to be limited despite PR, possibly as a consequence of hyperinflation and the accompanying impairment of the extrapulmonary peripheral muscles. Our patients are similar to those with severe COPD evaluated in other studies, save for their more marked degree of resting hyperinflation, with a mean functional residual capacity of 6.
Although we followed an incremental exercise test protocol similar to that described by Georgiadou et al. Our patients exercised with a high fraction of their MVV at peak exercise, and their end-inspiratory lung volume reached their predicted TLC.
After PR, there was a small yet statistically significant increase in peak workload similar to that reported in other studies employing incremental exercise tests, 1 , 8 and that was reflected in a similar improvement in the 6MWD. Like other authors, we observed no relationship between the timing of the change in chest wall volume and the response to PR.
In a recent study, we observed that changes in the EECWV during exercise are associated with the presence of paradoxical movement of the lower rib cage at rest. Although the total EECWV was unaffected by PR, there was a post-PR decrease in the rib cage volumes, with less recruitment of the abdominal compartment during exercise. The end-expiratory abdominal volume remained constant and there was a proportionate decrease in the volume contained within the rib cage compartment at any given workload.
Although the EECWV was unaffected by PR in either subgroup, this new behavior in the rib cage and abdominal compartments after PR, resulting in a more physiological pattern and less distortion of the total chest wall, was seen only in the improvers. However, in the study conducted by Georgiadou et al. These discrepancies might reflect differences in the resting lung volumes, our hyperinflated subjects tending to show a reduction in tidal volume rather than in the respiratory rate.
Another possible explanation is that the exercise regimes employed may have been different, particularly because some of the patients evaluated by Georgiadou et al. In the present study, there was a high level of adherence to treatment. Nevertheless, some patients failed to improve in terms of their response to the incremental exercise test or their 6MWD. In general, the non-improvers exercised to a lower peak workload before PR and tended to have more severe resting hyperinflation than did the improvers, although the small numbers of patients in each of the subgroups precluded any inferences regarding statistical significance.
Previous studies have suggested that there are differences among patients in terms of the ability of peripheral muscles to increase their VO 2 during exercise, 19 which could explain why some COPD patients are limited by peripheral muscle fatigue rather than by ventilatory factors. The changes in regional operating lung volumes were confined to the patients who improved their exercise performance, suggesting that such changes were secondary to the reduced overall metabolic drive to breathing at any given workload. After PR, the improvers had a relatively slower and deeper breathing pattern at any V E , which could explain why these patients were able to exercise for longer without further increasing their reported levels of breathlessness.
However, whether the change in rib cage volume was a result of a reduction in the activation of the muscles acting on that compartment or a consequence of a reduced central respiratory drive cannot be answered on the basis of our findings in the present study. In contrast, the non-improvers reported higher degrees of muscle fatigue before PR, which were still present at lower absolute workloads after PR. The fact that the non-improvers showed no improvement in VO 2 and no decrease in VCO 2 could explain why they also showed no post-PR changes in V E or regional chest wall volumes.
Our study has certain limitations. We used a relatively arbitrary threshold to define improvers and non-improvers in terms of the response to the incremental exercise test, given that there is no established minimum clinically important difference for that test. However, our findings were unchanged when we separated patients according to the ability to achieve a clinically important improvement in the 6MWD after PR. In addition, the protocol involved incremental rather than constant-load exercise, which could have decreased its sensitivity to detect post-PR improvements in exercise capacity.
Nevertheless, the use of incremental exercise allowed us to analyze variables at different exercise intensities over the course of the test. Furthermore, we did not specifically identify peripheral muscle weakness, although that would be a plausible explanation for the differences we observed. Future studies of COPD patients who do not improve after PR, however they are defined, should include objective measurements of peripheral muscle fatigue. The small number of patients who did not improve after our PR is encouraging given our selection of individuals with significant hyperinflation.
1.04 Respiratory disease
Finally, we did not measure ventilatory muscle strength, which could have had some effect on the operating volumes during exercise. In summary, we have shown that in COPD patients with resting hyperinflation the major effect that PR has on exercise capacity is that of improving VO 2 and reducing VCO 2 , with a commensurate decrease in respiratory drive. The changes in operating lung volumes reflect this reduction in respiratory drive for a given workload.
When severe hyperinflation is present, the ability to reduce operating lung volumes with a reduction in respiratory drive is more limited, although subtle changes in the distribution of volume between the rib cage and abdominal compartments could be a useful way to delay the onset of limiting symptoms. Such changes occurred only in patients in whom an objective training effect could be demonstrated.
It is encouraging to see that a majority of patients with severe COPD can improve after completing a conventional non-specific exercise program. However, certain patients those with significant resting hyperinflation might require a different approach to rehabilitation and those in whom breathlessness or leg fatigue is a dominant symptom at low workloads might require specific peripheral muscle training. Effects of rehabilitation on chest wall volume regulation during exercise in COPD patients. Eur Respir J. Exercise training improves exertional dyspnea in patients with COPD: evidence of the role of mechanical factors.
Vogiatzis I, Zakynthinos S. The physiological basis of rehabilitation in chronic heart and lung disease. J Appl Physiol Exercise rehabilitation and chronic obstructive pulmonary disease stage. Exercise training in COPD: how to distinguish responders from nonresponders. J Cardiopulm Rehabil. Reductions in exercise lactic acidosis and ventilation as a result of exercise training in patients with obstructive lung disease.
Am Rev Respir Dis. Vogiatzis I. Strategies of muscle training in very severe COPD patients. Exercise training decreases ventilatory requirements and exercise-induced hyperinflation at submaximal intensities in patients with COPD. A controlled trial of the effects of leg training on breathing pattern and dynamic hyperinflation in severe COPD.
Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: GOLD executive summary. Standardisation of spirometry. Standardisation of the measurement of lung volumes. Recommendations on the use of exercise testing in clinical practice. References values for forced spirometry.
Stocks J, Quanjer PH. Reference values for residual volume, functional residual capacity and total lung capacity. Reference values for a multiple repetition 6-minute walk test in healthy adults older than 20 years.pierreducalvet.ca/15582.php
Borg GA. Psychophysical bases of perceived exertion.
Med Sci Sports Exerc. Chest wall and lung volume estimation by optical reflectance motion analysis. Regional chest wall volumes during exercise in chronic obstructive pulmonary disease. Lower limb activity and its determinants in COPD. Chest wall kinematics and breathlessness during unsupported arm exercise in COPD patients. Respir Physiol Neurobiol. Dynamic hyperinflation and exercise intolerance in chronic obstructive pulmonary disease. Calverley PM. Dynamic hyperinflation: is it worth measuring? Proc Am Thorac Soc. Mechanisms of dyspnea during cycle exercise in symptomatic patients with GOLD stage I chronic obstructive pulmonary disease.
Paradoxical movement of the lower ribcage at rest and during exercise in COPD patients. Contractile leg fatigue after cycle exercise: a factor limiting exercise in patients with chronic obstructive pulmonary disease. Symptoms and quadriceps fatigability after walking and cycling in chronic obstructive pulmonary disease. Aliverti A, Macklem PT. The major limitation to exercise performance in COPD is inadequate energy supply to the respiratory and locomotor muscles. The purpose is to evaluate exercise performance in patients with Chronic Obstructive Pulmonary Disease COPD after supplementing with higher doses of dietary NO3-, compared to previous studies, as beetroot juice for seven days.
The secondary purpose is to evaluate oxygen consumption of submaximal cycling, amendments in blood pressure, and physical activity level. The purpose is to evaluate exercise performance in patients with Chronic Obstructive Pulmonary Disease COPD using the 6-minute walk test 6MWT after supplementing with higher doses of dietary NO3- compared to previous studies, as beetroot juice for seven days.
FDA Resources. Arms and Interventions. Consumed as concentrated beetroot juice from James White Drinks England Beet-it and contained mg dietary nitrate. The intervention beverage Dietary beetroot juice was administrated in the first period of the cross-over trial, while placebo was administrated in the second period of the trail Intervention beverage, Dietary beetroot juice:Consumed as beetroot juice from James White Drinks England Beet-it and contained mg dietary nitrate.
Outcome Measures. Eligibility Criteria. Exclusion Criteria: Smoking, failure to complete physical testing, on-going participation in rehabilitation programs, pacemaker or use of nicotine products, oxygen mask, beta blockers, antibacterial mouthwash, chewing gum or stomach-neutralizing medicine during the intervention. Contacts and Locations. Information from the National Library of Medicine To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
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Please refer to this study by its ClinicalTrials. More Information. Dietary nitrate Physical performance Blood pressure Nitrite Exercise.