Lee 2018.

Study characteristics
Methods	RCT, cross‐over design. Single‐centre study
Participants	Total number of randomized participants: 26 Setting: ICU; South Korea Inclusion criteria: age > 20 years; subjective dyspnoea in room air; SpO2 < 90% in room air; oxygen requirement for nasal cannula < 6 L/min Exclusion criteria: unstable vital signs; severe hypoxia; unable to co‐operate; symptomatic Ischaemic heart disease; use of accessory muscle heart disease; use of accessory muscle under oxygen therapy using nasal cannula; impracticality of HFNC or NC application; facial deformity Baseline characteristics (overall): Age, mean (SD): 67.9 (± 13.4) years Gender, M/F: 15/9 BMI, mean (SD): 24.0 (± 2.9) kg/m2 APACHE II: not reported PaCO2, mean (SD): 38.2 (± 7.8) mmHg PaO2/FiO2, mean (SD): 332.9 (± 112.9) mmHg
Interventions	Cross‐over study design, participants received each of two therapies for 20 minutes each: HFNC: oxygen delivered using OmniOx System, initial gas flow rate at 35 L/min with FiO2 at 35% mmHg, then adjusted at discretion of the physician. One participant only received 15 L/min. Oxygen via conventional nasal cannula: no additional details Randomized, n = 26; losses, n = 2 (withdrew consent); analysed, n = 24
Outcomes	Flow rates; tidal volumes; comfort (10‐point scale) Note: we did not report outcome data in the review because study authors did not include outcome data from the first period.
Notes	Funding/declarations of interest: Draeger provided EIT monitor. Study author declared no potential conflict of interest, and funder had no role in the design, collection, analysis or interpretation of the study. Study dates: 1 October 2014 to 28 February 2015 Note: we did not conduct 'Risk of bias' assessments for this study because we did not report outcome data in the review.