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

RationaleIn patients with COPD, oxygen (O2)-supplementation via a constant flow oxygen system (CFOS) can result in insufficient oxygen saturation (SpO22-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.MethodsFifty participants completed this prospective randomised controlled, double-blind, crossover trial. Participants performed two endurance shuttle walk tests (ESWTs) with: (1) exercise titrated CFOS (ESWTCFOS) and (2) ATOS targeting an SpO2of 92% (ESWTATOS). 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.ResultsParticipants (median (IQR): age 66 (59, 70) years, FEV128.8 (24.8, 35.1) % predicted, PO254.7 (51.0, 57.7) mm Hg, PCO244.2 (38.2, 47.8) mm Hg) walked significantly longer with ESWTATOSin comparison to ESWTCFOS(median effect (95% CI) +144.5 (54 to 241.5) s, p2was significantly higher (+3 (95% CI 1 to 4) %, p2, 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 p2was comparable.ConclusionIn patients with hypoxaemia with severe COPD the use of ATOS leads to significant, clinically relevant improvements in walking endurance time, SpO2, PO2and dyspnoea with no impact on PCO2.Trial registration numberNCT03803384.