Pulmonary Rehabilitation* Joint ACCP/AACVPR Evidence-Based Clinical Practice Guidelines

Andrew L. Ries, MD, MPH, FCCP (Chair); Gerene S. Bauldoff, RN, PhD, FCCP; Brian W. Carlin, MD, FCCP; Richard Casaburi, PhD, MD, FCCP; Charles F. Emery, PhD; Donald A. Mahler, MD, FCCP; Barry Make, MD, FCCP; Carolyn L. Rochester, MD; Richard ZuWallack, MD, FCCP; Carla Herrerias, MPH


CHEST. 2007;131(5):4S-42S. 

In This Article

Oxygen Supplementation as an Adjunct to Pulmonary Rehabilitation

It was demonstrated > 25 years ago that long-term oxygen supplementation prolongs survival in patients with COPD and severe resting hypoxemia.[159,160] More recently, the usefulness of oxygen therapy in improving outcomes from pulmonary rehabilitation in patients with COPD has been evaluated in several RCTs. A distinction must be made between the immediate effect of oxygen on exercise performance and its usefulness in the exercise-training component of pulmonary rehabilitation.[161] This section will review the latter.

As an adjunct to exercise training, supplemental oxygen therapy has been studied in the following two situations: (1) patients who are severely hypoxemic at rest or with exercise; and (2) patients who do not have severe hypoxemia. The rationale for these studies is that supplemental oxygen therapy improves dyspnea and exercise capacity in patients with COPD and hypoxemia,[162,163] and even in those without exercise-induced hypoxemia,[164] possibly allowing them to train at higher intensities. These studies, which evaluated exercise performance and, in some instances, HRQOL, are summarized in Table 10 .

Rooyackers and colleagues[165] randomized 24 patients with severe COPD who were referred to pulmonary rehabilitation and who experienced hypoxemia during exercise testing (arterial oxygen saturation [SaO 2] at maximum exercise, < 90%) into the following two groups: (1) exercise training with room air; and (2) exercise training with supplemental oxygen administered at a rate of 4 L/min. The exercise-training intensity was increased as tolerated, but the work rate was adjusted to keep SaO 2 at > 90% in all patients. Health status was measured using the CRDQ. In prerehabilitation testing, compared with breathing room air, the use of supplemental oxygen was associated with greater maximal cycle exercise performance and 6-min walk distances. However, exercise training with supplemental oxygen did not enhance the benefits of exercise training with respect to exercise performance measured while breathing room air or on health status measurements. These negative results might be explained by the fact that the mean work rate during interval cycle exercise training during the last 6 weeks was not significantly different between the two groups (p = 0.12).

Garrod and Wedzicha[166] randomized 25 patients with severe COPD and exercise-hypoxemia into 18 sessions of exercise training breathing room air or supplemental oxygen (4 L/min) over 6 weeks. Patients were instructed to exercise as long as possible at a high intensity. In the short term, supplemental oxygen therapy improved the shuttle walk distance and symptoms of dyspnea in test results before rehabilitation. However, supplemental oxygen therapy with exercise training did not enhance the postrehabilitation gains in exercise performance, health status, or questionnaire-measured functional status. These results might be explained by the fact that the group receiving oxygen supplementation did not have significantly higher oxygen saturation levels than the nonsupplemented group. There was a small improvement in exertional dyspnea following rehabilitation with oxygen therapy.

Wadell and colleagues[167] randomized 20 patients with COPD and exercise-induced hypoxemia into training with or without supplemental oxygen (at a rate of 5 L/min). Training involved 30-min sessions on a treadmill three times weekly for 8 weeks. Training intensity was individualized to target dyspnea and perceived exertion ratings and to maintain SaO 2 at > 90%. Oxygen supplementation led to longer walk test distances before and after rehabilitation. However, there were no significant between-group differences in exercise-training effects at the end of the rehabilitation period, when patients were tested either while breathing room air or supplemental oxygen. In fact, there was a trend for greater improvement in those patients who trained while breathing room air.

The studies described above evaluated the effect of oxygen in patients who experienced hypoxemia during exercise. More recently, Emtner and colleagues[168] evaluated the use of supplemental oxygen as an adjunct to exercise training in patients with COPD who did not meet the standard criteria for oxygen supplementation. Unlike previous studies, this randomized trial was double-blinded. Twenty-nine patients without significant exercise-induced oxygen desaturation were randomized to receive compressed air or oxygen (at a rate of 3 L/min) during high-intensity exercise training. Patients were trained in 21 sessions over a 7-week period with a target intensity of 75% of the baseline peak work rate on a cycle ergometer, which was progressively adjusted according to the patient's perceived level of dyspnea and fatigue. The results indicated that patients receiving oxygen were able to train at higher intensities. After exercise training, endurance time at a constant work rate improved more in the group receiving supplemental oxygen therapy (14.5 min) compared with the group breathing room air (10.5 min; p < 0.05). This improvement in exercise performance was accompanied by a reduction in respiratory rate at isotime during the tests. A recent metaanalysis[169] of these trials concluded that there was a trend toward greater improvement in constant-work-rate test results and health status with oxygen supplementation, but the opposite effect was present with the 6-min walk test distance.

In summary, the use of continuous supplemental oxygen for patients with COPD and severe resting hypoxemia is clearly indicated and recommended as a part of routine clinical practice. From a safety perspective, there is a strong rationale to administer supplemental oxygen during exercise training for patients with severe resting or exercise hypoxemia. However, while oxygen use improves maximal exercise performance acutely in the laboratory, studies testing its effect in enhancing the exercise-training effect have produced inconsistent results. This may reflect differences in methodology among the studies, especially with respect to intensity targets for training. Of note, most of the studies reviewed evaluated supplemental oxygen administered at a rate of 3 to 5 L/min, which is higher than that used in the typical clinical setting. As described above, one well-designed study[168] of supplemental oxygen therapy for nonhypoxemic patients with COPD who trained at high intensity showed greater improvement in exercise capacity with oxygen therapy. The long-term benefit when supplemental oxygen is discontinued and the effect on other outcomes such as HRQOL remain to be determined.

20. Supplemental oxygen should be used during rehabilitative exercise training in patients with severe exercise-induced hypoxemia. Grade of recommendation, 1C

21. Administering supplemental oxygen during high-intensity exercise programs in patients without exercise-induced hypoxemia may improve gains in exercise endurance. Grade of recommendation, 2C


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