Abstract
BACKGROUND: The acute effect of supplemental oxygen during exercise has been shown to differ largely among patients with COPD. It is unknown what factors influence oxygen response.
METHODS: In a randomized, single-blind fashion, 124 patients with COPD underwent one 6-min walk test on supplemental oxygen (6MWT(O2)) and one 6-min walk test on room air after a practice 6-min walk test. Both gases were delivered via standard nasal prongs (2 L/min). For analyses, patients were stratified on the basis of PaO2 values and compared: (1) 34 patients with resting hypoxemia (HYX); (2) 43 patients with exercise-induced hypoxemia (EIH); and (3) 31 patients with normoxemia (NOX).
RESULTS: Oxygen supplementation resulted in an increase in the 6-min walk distance in the total cohort (27 +/- 42 meters; P <.001) and in the subgroups of HYX (37 +/- 40 meters; P <.001) and EIH (28 +/- 44 meters; P <.001) but not in the NOX subgroup (15 +/- 43 meters; P = .065). Forty-two percent of patients with HYX and 47% of patients with EIH improved their 6-min walk distance to a clinically relevant extent (>= 30 meters) by using oxygen. These oxygen responders were characterized by significantly lower 6-min walk distance using room air compared with patients without a relevant response (306 +/- 106 meters vs 358 +/- 113 meters; P <.05). Although oxygen saturation was significantly higher during 6MWT(O2) compared with the 6-min walk test on roomair in all 3 subgroups, it dropped to <88% during 6MWT(O2) in 73.5% of patients with HYX.
CONCLUSIONS: In contrast to patients with NOX, patients with HYX and EIH generally benefit from supplemental oxygen by increasing exercise capacity. However, less than one-half of patients reached the threshold of clinically relevant improvements. These oxygen responders were characterized by significantly lower exercise capacity levels.
Original language | English |
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Pages (from-to) | 795-803 |
Number of pages | 9 |
Journal | Chest |
Volume | 151 |
Issue number | 4 |
DOIs | |
Publication status | Published - Apr 2017 |
Keywords
- 6-min walking distance
- COPD
- exercise-induced hypoxemia
- exercise testing
- supplemental oxygen
- OBSTRUCTIVE PULMONARY-DISEASE
- CHRONIC RESPIRATORY-DISEASE
- EXERCISE
- HYPERINFLATION
- LUNG