The effects of high-flow vs low-flow oxygen on exercise in advanced obstructive airways disease

Study objectives: Current options to enhance exercise performance in patients with COPD are limited. This study compared the effects of high flows of humidified oxygen to conventional low-flow oxygen (LFO) delivery at rest and during exercise in patients with COPD. Design: Prospective, nonrandomized, nonblinded study. Setting: Outpatient exercise laboratory. Patients: Ten patients with COPD, stable with no exacerbation, and advanced airflow obstruction (age, 54 +/- 6 years; FEV1, 23 +/- 6% predicted [mean +/- SD]). Interventions: After a period of rest and baseline recordings, patients were asked to exercise on a cycle ergometer for up to 12 min. Exercising was started on LFO first; after another period of rest, the patients repeated exercising using the high-flow oxygen (HFO) system, set at 20 L/min and matched to deliver the same fraction of inspired oxygen (FIO2) as that of LFO delivery. Measurements and results: Work of breathing and ventilatory parameters (tidal volume, respiratory rate, inspiratory time fraction, rapid shallow breathing index, pressure-time product) were measured and obtained from a pulmonary mechanics monitor. Borg dyspnea scores, pulse oximetry, blood gases, vital signs were also recorded and compared between the two delivery modes. Patients were able to exercise longer on high flows (10.0 +/- 2.4 min vs 8.2 +/- 4.3 min) with less dyspnea, better breathing pattern, and lower arterial pressure compared to LFO delivery. In addition, oxygenation was higher while receiving HFO at rest and exercise despite the matching of FIO2. Conclusion: High flows of humidified oxygen improved exercise performance in patients with COPD and severe oxygen dependency, in part by enhancing oxygenation.