High flow oxygen therapy during exercise training in COPD patients with chronic respiratory failure: a multicenter randomised trial.

Background. High-flow oxygen therapy (HFOT) improves exercise capacity, oxygen saturation and symptoms in severe COPD. We wondered whether additional HFOT during training was more effective than oxygen through a Venturi Mask (V-mask) in improving exercise capacity in people with COPD and chronic respiratory failure (CRF). Methods. Patients (n=171) were randomized to receive either HFOT or oxygen through a V-mask at iso inspiratory oxygen fraction during the same intensity exercise training program. Pre- and post-training endurance time (Tlim), six minutes walking distance (6MWD), respiratory and limb muscle strength, arterial blood gases, Barthel and Barthel Dyspnea Indices, COPD Assessment Test, Maugeri Respiratory Failure questionnaire and patient satisfaction were evaluated. Results. Due to 15.4% and 24.1% dropout rates, 71 and 66 patients were analyzed in the HFOT and V-mask groups, respectively. Exercise capacity significantly improved after training in both groups with similar patients’ satisfaction. The improvement in 6MWD, (with 18 meters as mean difference between groups) but not in Tlim, was significantly higher in the HFOT group (p=0.029). The minimal clinically important difference (MCID) of Tlim was reached by 44% of V-mask and 56% of HFOT patients (p=0.867), whereas the MCID of 6MWD post-training was reached by 51% of V-mask and 69% of HFOT patients respectively (p= 0.036).