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Abstract
BACKGROUND: Oxygen administration is recommended for patients with hypoxemia to achieve a target 
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 
≥ 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 
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 
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 
outside a target saturation range using a model of exercise-induced desaturation and subsequent recovery.
Footnotes
- Correspondence: James CP Harper MBChB MRCP. Medical Research Institute of New Zealand, Private Bag 7902, Newtown, Wellington 6242, New Zealand. E-mail: james.harper{at}mrinz.ac.nz
This work was supported by Fisher and Paykel Healthcare and the MRINZ receives funding from the Health Research Council of New Zealand as an Independent Research Organisation grant. The authors have disclosed no conflicts of interest.
Supplementary material related to this paper is available at http://www.rcjournal.com.
- Copyright © 2021 by Daedalus Enterprises
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