Closed-loop oxygen control using a novel nasal high-flow device: a randomized crossover trial

Abstract

BACKGROUND: Oxygen administration is recommended for patients with hypoxemia to achieve a target SpO2 range. Strategies to achieve this in clinical practice are suboptimal. We investigated automatic oxygen titration using a novel nasal high-flow device with closed-loop oxygen control. The objective of this proof-of-concept study was to determine whether closed-loop control was able to respond to desaturation and subsequent recovery in a controlled laboratory-based environment. METHODS: We conducted a single-blind randomized crossover trial in adults with chronic respiratory disease who had a resting SpO2 ≥ 92% and desaturated to < 90% during a 6-min walk test (6MWT). Nasal high-flow was administered during a 6MWT and a subsequent 10-min rest period with either room air, a fixed concentration of 28% oxygen, or oxygen titrated automatically using closed-loop control. RESULTS: The study involved 42 subjects. Closed-loop control maintained SpO2 within the target range of 92–96% for a mean (SD) duration of 54.4 ± 30.1% of the 6MWT and 67.3 ± 26.8% of the recovery period. The proportion of time spent with an SpO2 in the target range during the 6MWT was significantly greater for closed-loop control compared to room air, with a difference of 26.0% (95% CI 17.7–34.2, P < .001); this proportion of time was not significantly different compared to the fixed concentration of 28% oxygen, with a difference of –8.2% (95% CI –16.5 to 0.1, P = .052). The proportion of time spent in the target range during the rest period was significantly greater compared to 28% oxygen, with a difference of 19.3% (95% CI 8.9–29.7, P < .001); this proportion of time was not significantly different compared to room air, with a difference of –9.3% (95% CI –19.7 to 1.0, P = .08). CONCLUSIONS: This study provides proof-of-concept evidence that the novel nasal high-flow device with closed-loop control can respond to changes in SpO2 outside a target saturation range using a model of exercise-induced desaturation and subsequent recovery.