BackgroundGuideline recommendations state oxygen should be administered to acutely unwell patients to achieve a target oxygen saturation (SpO₂) range. The current practice of manual oxygen titration frequently results in SpO₂ outside of a prescribed range. The aim of this study was to assess the efficacy of automatic oxygen titration using a closed-loop feedback system to achieve SpO₂ within a prescribed target rangeMethodsAn open-label randomised parallel group trial was undertaken comparing automatic oxygen titration using a novel nasal high-flow device to manual oxygen titration using nasal high flow. Medical inpatients requiring oxygen therapy in Wellington Regional Hospital, New Zealand with a prescribed target SpO₂ range of 88%–92% or 92%–96% were recruited and randomised equally between the interventions for a period of 24 hours. The primary outcome was the proportion of time spent with SpO₂ within the prescribed range.Results20 patients were included in the analysis. Automatic oxygen titration resulted in a median (IQR) 96.2% (95.2–97.8) of time within the target range compared with 71% (59.4–88.3) with manual titration; difference (95% CI) 24.2% (7.9% to 35%), p<0.001. There was a reduction in the time spent with SpO₂ ≥2% above and ≥2% below range in the automatic titration group, although the point estimate for the differences were small; −1% (−8.2% to −0.04%), p=0.017 and −2.4% (−11.5% to 0.3%), p=0.05 respectively.ConclusionsNasal high-flow with automatic oxygen titration resulted in a greater proportion of time spent with SpO₂ in target range compared with manual titration.Trial registrationThe trial was registered with the Australian and New Zealand Clinical Trials Registry (ACTRN12619000901101).