Oxygen supplementation in ambulatory patients with heart failure: a randomized proof-of-concept study.

Aims: The aims of this study were to describe the short-term effects of oxygen therapy on the physiological response and symptoms during ambulation in patients with chronic heart failure (HF).

Methods and results: In this pilot, cross-over, randomized study, subjects with chronic HF underwent two 6-min walk tests (6MWTs) on the same day. They were randomized to either receive oxygen through a portable oxygen concentrator (POC ON) during the first test and no oxygen (POC OFF) during the second test, or vice versa. Endpoints included (i) peripheral oxygen saturation, (ii) heart rate, and (iii) modified BORG scale. A linear mixed model for repeated measures was used for comparisons. A total of 20 participants were included, aged 70 ± 10 years, with the mean left ventricular ejection fraction 33% ± 10% and N-terminal pro-B-type natriuretic peptide 1115 ± 1625 pg/mL. There was no difference in distance walked with or without oxygen supplementation. Oxygen saturation during 6MWT was higher with POC ON [3 min, SpO₂ + 3.4%, 95% confidence interval (CI) 1.8-5.0%; 6 min, + 2.8%, 95% CI 2.2-3.3%]. Heart rate recovery tended to be better in patients with POC ON (difference 7.4 b.p.m., 95% CI -2.4 to 17.2). Perceived exertion and fatigue were significantly lower with POC ON during exercise (3 min, -0.7, 95% CI -1.2 to -0.2; 6 min, -0.75, 95% CI -1.1 to -0.4; and 3 min into recovery, -0.5, 95% CI -0.8 to -0.2).

Conclusion: Our results suggest that for a same amount of physical activity, supplemental oxygen can improve peripheral oxygen saturation and breathlessness in symptomatic patients with chronic HF.