Abstract: Methods and systems for capturing capnography data during high-flow oxygen therapy (HFOT) are disclosed. An example method includes delivering HFOT by delivering breathing gases at an operational flow rate and an operational oxygen concentration level; initiating a temporary flow-reduction function for a set duration, wherein breathing gases are delivered at a temporary flow rate for the set duration, the temporary flow rate being less than the operational flow rate; capturing capnography data for exhaled air during the set duration; and upon expiration of the set duration, resuming HFOT delivery.