Effect of domiciliary oxygen therapy on exercise capacity and quality of life in patients with pulmonary arterial or chronic thromboembolic pulmonary hypertension: a randomised, placebo-controlled trial.

Abstract

We investigated whether domiciliary oxygen therapy (DOXT) increases exercise capacity and quality of life in patients with pulmonary arterial or distal chronic thromboembolic pulmonary hypertension (PAH/CTEPH) presenting with mild resting hypoxaemia and exercise-induced oxygen desaturation. 30 patients with PAH/CTEPH, mean±sd age 60±15 years, pulmonary artery pressure 39±11 mmHg, resting arterial oxygen saturation measured by pulse oximetry (S pO2 ) ≥90%, S pO2 drop during a 6-min walk test ≥4%, on pulmonary hypertension-targeted medication, were randomised in a double-blind crossover protocol to DOXT and placebo (ambient air) treatment, each over 5 weeks, at 3 L·min-1 via nasal cannula overnight and when resting during the day. Treatment periods were separated by 2 weeks of washout. Co-primary outcomes were changes in 6-min walk distance (6MWD, breathing ambient air) and physical functioning scale of the 36-item short-form medical outcome questionnaire during treatment periods. DOXT increased the 6MWD from baseline 478±113 m by a mean (95% CI) of 19 (6-32) m, and physical functioning from 52±29 by 4 (0-8) points. Corresponding changes with placebo were 1 (-11-13) m in 6MWD and -2 (-6-2) points in physical functioning. Between-treatment differences in changes were 6MWD 18 (1-35) m (p=0.042) and physical functioning 6 (1-11) points (p=0.029). DOXT significantly improved the NewYork Heart Association functional class versus placebo. This first randomised trial in PAH/CTEPH patients with exercise-induced hypoxaemia demonstrates that DOXT improves exercise capacity, quality of life and functional class. The results support large long-term randomised trials of DOXT in PAH/CTEPH.