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

The question addressed by the study: 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 hypoxemia and exercise-induced oxygen desaturation.

Materials and Methods: 30 patients with PAH/CTEPH, mean age (±sd) 60±15 y, pulmonary artery pressure 39±11 mmHg, resting pulse oximetry (SpO₂) ≥90%, SpO₂ drop during a 6MWD ≥4%, on PH-targeted medication, were randomised in a double-blind cross-over protocol to DOXT and placebo (ambient air) treatment, each during 5 weeks, at 3 L·min⁻¹ via nasal cannula during nights and daytime when resting. Treatment periods were separated by 2 weeks wash-out. Co-primary outcomes were changes in 6-min walk distance (6MWD, breathing ambient air) and physical functioning scale (PF) of the short form medical outcome questionnaire (SF-36) during treatment periods.

Results: DOXT increased the 6MWD from baseline 478±113 m by a mean (95%CI) of 19 m (6 to 32), and PF from 52±29 by 4 points (0 to 8). Corresponding changes with placebo were 1 m (−11 to 13) in 6MWD and −2 points (−6 to 2) in PF. Between-treatment differences in changes were 6MWD 18 m (1 to 35, p=0.042) and PF 6 points (1 to 11, p=0.029). DOXT significantly improved the NYHA functional class versus placebo.

Answer to the question: This first randomised trial in PAH/CTEPH patients with exercise-induced hypoxemia demonstrates that DOXT improves exercise capacity, quality of life and functional class. The results support large long-term randomised-trial of DOXT in PAH/CTPEH.

Trial registration: clinicaltrials.gov NCT01884012.