Hu 2020.

Study characteristics
Methods	RCT, parallel‐group design. Single‐centre study
Participants	Total number of randomized participants: 56 Setting: medical ICU; Taiwan Inclusion criteria: adults admitted to the ICU with acute respiratory failure and mechanically ventilated for > 48 hours, successfully passed a SBT; meeting at least one risk factor for high‐risk extubation failure Exclusion criteria: < 20 years of age; tracheostomy; pregnancy; facial trauma with intolerable post‐extubation facial mask or HFNC use; acute gastrointestinal bleeding; planning to use NIV after extubation Baseline characteristics: Intervention group (HFNC): Age, mean (SD): 72.9 (± 13.1) years Gender, M/F: 22/7 BMI, > 30 kg/m2, n: 3 APACHE II, median IQR: 27 (23 to 29) PaCO2, mean (SD): 42 (± 7.9) mmHg PaO2/FiO2, mean (SD): 320 (± 89.6) mmHg Control group (conventional oxygen therapy): Age, mean (SD): 74.9 (± 11.4) years Gender, M/F: 17/10 BMI, > 30 kg/m2, n: 3 APACHE II, median (IQR): 25 (22‐30) PaCO2, mean (SD): 38 (± 7.4) mmHg PaO2/FiO2, mean (SD): 279 (± 90.6) mmHg
Interventions	Intervention group: Randomized, n = 29; losses, n = 0; analysed, n = 29 Details: HFNC using Optiflow, immediately after extubation, humidified temperature initially set to 37 ºC, flow rate initially at 40 L/min with adjustments of 5 to 10 L/min (to maximum of 60 L/min). FiO2 titrated to maintain SpO2 > 92% (or 88‐95% for compensated hypercapnia). Applied for at least 72 hours, then maintained or given conventional therapy Control group: Randomized, n = 27; losses, n = 0; analysed, n = 27 Details: post‐extubation, conventional oxygen therapy delivered continuously through nasal prongs with flow rate 1 to 4 L/min, or via Venturi facemask with oxygen and flow titrated to deliver FiO2 between 35% and 100% and to maintain SpO2 > 92% (or 88 to 95% for compensated hypercapnia). Applied for at least 72 hours, then maintained if required
Outcomes	Respiratory failure within 72 hours (requiring rescue management with oxygen therapy, NIV, or reintubation); time to post‐extubation failure within 72 hours; multiple organ failure; ICU length of stay; 28‐day all‐cause mortality (in‐hospital); 48‐hour respiratory and haemodynamic variables (heart rate, MAP, PaO2, PaCO2); causes of respiratory failure (dyspnoea or hypoxia, respiratory acidosis, decreased levels of consciousness, stridor or upper airway problems)
Notes	Funding/declarations of interest: funding not reported. Study authors declared no competing interests. Study dates: September 2014 to December 2016
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	1:1 block randomization used
Allocation concealment (selection bias)	Unclear risk	No details
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Blinding was not possible and we did not expect it to influence outcome data. However, the influence on RoB remains unclear.
Blinding of outcome assessors (objective outcomes)	Low risk	Blinding of outcome assessors. Although we expected that this would not influence outcome data, we could not be certain of this.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No participant losses
Selective reporting (reporting bias)	High risk	Study was prospectively registered with a clinical trials register (NCT 02290548). Whilst most review outcomes were reported according to these trial register documents, we noted that study authors did not report data for hospital length of stay and for pneumonia; this may indicate selective reporting bias for these outcomes.
Other bias	Low risk	We identified no other sources of bias.