Automatic oxygen titration versus constant oxygen flow rates during walking in COPD: a randomised controlled, double-blind, crossover trial.

Abstract

In patients with COPD, oxygen (O₂)-supplementation via a constant flow oxygen system (CFOS) can result in insufficient oxygen saturation (SpO₂ <90%) during exercise. An automatically titrating O₂-system (ATOS) has been shown to be beneficial compared with an untitrated CFOS, however, it is unknown if ATOS is superior to CFOS, titrated during exercise as stipulated by guidelines. The aim was to investigate the effects of ATOS compared with titrated CFOS on walking capacity in people with hypoxaemic COPD. Fifty participants completed this prospective randomised controlled, double-blind, crossover trial. Participants performed two endurance shuttle walk tests (ESWTs) with: (1) exercise titrated CFOS (ESWT_CFOS) and (2) ATOS targeting an SpO₂ of 92% (ESWT_ATOS). Primary outcome measure was walking time. Secondary measures were SpO₂, transcutaneous-PCO₂ (TcPCO₂), respiratory rate (RR), heart rate (HR) at isotime (end of shortest ESWT) with blood gases and dyspnoea at rest and end exercise. Participants (median (IQR): age 66 (59, 70) years, FEV₁ 28.8 (24.8, 35.1) % predicted, PO₂ 54.7 (51.0, 57.7) mm Hg, PCO₂ 44.2 (38.2, 47.8) mm Hg) walked significantly longer with ESWT_ATOS in comparison to ESWT_CFOS (median effect (95% CI) +144.5 (54 to 241.5) s, p<0.001). At isotime, SpO₂ was significantly higher (+3 (95% CI 1 to 4) %, p<0.001) with ATOS while TcPCO₂, RR and HR were comparable. End exercise, PO₂ (+8.85 (95% CI 6.35 to 11.9) mm Hg) and dyspnoea (-0.5 (95% CI -1.0 to -0.5) points) differed significantly in favour of ATOS (each p<0.001) while PCO₂ was comparable. In patients with hypoxaemia with severe COPD the use of ATOS leads to significant, clinically relevant improvements in walking endurance time, SpO₂, PO₂ and dyspnoea with no impact on PCO₂. NCT03803384.