The use of inspiratory muscle resistive loading training plus nonventilatory muscle exercise (particularly walking) while breathing oxygen improves exercise performance and endurance in COPD patients during ten-week outpatient therapy.
We found that the classic parameters of a training response (increased Vo2 max and decreased heart rate) did not significantly improve after pulmonary rehabilitation. This is consistent with the reports that patients with COPD cannot exercise at an intensity high enough to induce an aerobic training response. Nor do their resting pulmonary function tests (spirometry) or arterial blood gas levels improve after pulmonary rehabilitation.
Endurance time while breathing either room air or oxygen improved after pulmonary rehabilitation. The results shown in Figure 2 tend to underestimate thedegree of improvement, since the examiner terminated testing after the patient could perform the task for 20 min. Similarly, very significant improvement was noted in 12 min walk distances after rehabilitation while breathing either room air or oxygen. Maximum inspiratory force increased (became more negative) after rehabilitation in all patients. It is not clear whether this represents the beneficial effects of hyperventilation (from whole-body exercise or IMT, or both) or what part this improved inspiratory strength plays in the overall performance results. This improvement in inspiratory muscle strength is probably mediated by selective training of inspiratory muscles, however, since we and others have seen such improvement in patients who have received only IMT.
Oxygen desaturation with exercise is not uncommon in COPD patients (21 percent of our population studied). When it occurs before rehabilitation, it will usually be present after rehabilitation. However, we found no correlation between oxygen desaturation with exercise and FEVb exercise-induced bron-chospasm, Vo2 maximum, or ultimate performance. This emphasizes the predictive insensitivity of resting physiologic measurements (FEVb 02 saturation) to exercise performance. Because of this inability to predict which patient will develop exercise-induced hypoxemia, and because of its prevalence in this population, we feel that oximetry monitoring should be performed during all exercise testing of COPD patients, if possible. Hypoxemia may be a limiting factor for exercise and can also induce ECG changes whose cause might otherwise remain obscure.
Oxygen resulted in a reduction in Ve during sub-maximal work (25 W). This has also been reported by others. Furthermore, we found that breathing oxygen significantly improved performance over values while breathing room air in the same patient, both before and after rehabilitation. These observations may be physiologically linked. By reducing Ve with supplementary oxygen and therefore reducing the oxygen cost for additional ventilation, more oxygen becomes available for energizing nonrespiratory muscles, and the subject consequently may be able to exercise at a higher workload, where the effects of training may be more meaningful. This can have a significant therapeutic impact, since the oxygen cost of breathing during exercise is much greater in patients with COPD than in healthy subjects. We feel that oxygen supplementation is useful during exercise in all COPD patients, whether or not they desaturate with exercise. The website of Canadian Neighbor Pharmacy may represent to you the main ideas about diseases and their ways of treatment.
Patients who breathe oxygen during training subsequently improve their performance while breathing room air. Thus, we were able to reassure our patients that supplemental oxygen was just a training device and not a treatment that would need to be perpetuated after completing rehabilitation.
These physiologic changes translated, for most of our patients, into a substantial improvement in the quality of life. Many were now able to get out of the house and reenter social, vocational and recreational experiences that previously they could not perform. Many have sustained these improvements with home exercise and inspiratory muscle training programs. Psychologically, these patients as a whole are much less depressed and their outlook on life has improved significantly. Our patients are told that this is the beginning of a life-long process. The benefits that they derive from such a program can be expected to be sustained over the years, as long as they continue the principles of ongoing training. We feel, as do others, that a high degree of patient motivation is necessary for optimal results, and do not regard severity of lung disease as precluding successful outcome. Motivation is particularly necessary for the patient to continue after the formal three-month program is over. Early on, we noticed that many patients failed to continue exercise after the program terminated. We currently supplement the program with a monthly return to the pulmonary rehabilitation coordinator after the formal program has concluded. In addition, we have set up a maintenance “phase 3”-type program at the local YMCA for graduates, and a monthly support group at our hospital. We have no data as to the efficacy of these post-rehabilitation services, but sense that they are quite effective in preventing what otherwise frequently turns out to be lack of continuing exercise after formal rehabilitation.
Many unresolved questions remain, such as what is the proper initial exercise level, intensity, duration, and frequency of exercise in COPD? Is walking better than bicycling or arm-ergometry for these patients? How should work-load be incremented (eg, grade vs speed on treadmill) and when? What is the optimal oxygen concentration to administer during exercise in these patients, if indeed oxygen is beneficial at all? Which patients, with which types of lung disease, benefit most from such a program and which patients benefit the least? Is inspiratory resistive loading a better modality than eucapnic hyperventilation for training the inspiratory muscles in these patients? What are the ideal target goals in IMT and what parameters should be used to advance the IMT task? Should smokers be denied access to entering or staying in pulmonary rehabilitation programs?
We feel that an outpatient program of pulmonary rehabilitation concentrating only on those modalities that have been proven effective (exercise, inspiratory muscle training, and the use of supplemental oxygen) is within the capabilities of a community hospital, where most patients with obstructive lung diseases have the greatest access to health care. Moreover, such a program can demonstrably improve patients’ status, both subjectively and objectively.