Background: We hypothesized that breathing helium-hyperoxia (HeO2) would significantly improve 6-min walking test (6MWT) distance in COPD subjects.
Methods: This was a blinded, randomized crossover study. At visit 1, we assessed pulmonary function, exercise capacity, and 6MWT distance. Visits 2 and 3 consisted of four 6MWTs in which the following different inspired gases were used: room air (RA) by mask; 100% O2 by mask (mask O2); 100% O2 by nasal prongs (nasal O2); and 70% He/30% O2 by mask (HeO2). Walking distance, shortness of breath, leg fatigue, O2 saturation, and heart rate (HR) were assessed.
Results: Sixteen COPD subjects participated (mean FEV(1)/FVC ratio [+/- SD], 48 +/- 8%; mean FEV1, 55 +/- 13% predicted). Subjects walked farther when breathing HeO2 (564 m) compared to RA (497 m; p < 0.001), mask O2 (520 m; p < 0.001), or nasal O2 (528 m; p < 0.001). Despite the increased distance walked while breathing HeO2, there was no increase in shortness of breath or leg fatigue. There was desaturation when breathing RA (8%; p < 0.001) and nasal O2 (5%; p < 0.001), which was reduced when breathing HeO2 (3%; difference not significant) and mask O(2) (0%; difference not significant). There were no significant differences in HR in the four 6MWTs.
Conclusions: The use of HeO2 increased 6MWT distance in COPD subjects more than either mask O2 or nasal O2 compared to RA. The increased walking distance was not associated with increased shortness of breath or leg fatigue. The results suggest that clinical benefit would be obtained by administering HeO2 during exercise, which may have significant clinical implications for the management of COPD patients.