Fernandez 2017.

Study characteristics
Methods	RCT, parallel‐group design. Multicentre study
Participants	Total number of randomized participants: 155 Setting: 4 ICUs; Spain Inclusion criteria: adults receiving MV for > 12 hours and ready for scheduled extubation after a SBT; at high risk for extubation failure Exclusion criteria: tracheotomy; inability to follow commands; do‐not‐reintubate order; hypercapnia during SBT Baseline characteristics: Intervention group (HFNC): Age, mean (SD): 67.3 (± 12.1) years Gender, M/F: 46/32 BMI, > 30 kg/m2, n: 14 APACHE II, mean (SD) : 21 (± 8.8) PaCO2, mean (SD): not reported PaO2/FiO2, mean (SD): not reported Control group (conventional oxygen therapy): Age, mean (SD): 69.7 (± 13.0) years Gender, M/F: 55/22 BMI, > 30 kg/m2, n: 18 APACHE II, mean (SD): 21 (± 8.2) PaCO2, mean (SD): not reported PaO2/FiO2, mean (SD): not reported
Interventions	Intervention group: Randomized, n = 78; losses, n = 0; analysed, n = 78 Details: HFNC via Optiflow, flow initiated at 40 L/min, humidifier temperature at 37 ºC, but switched to noninvasive mode (34 ºC) if participant felt excessive warmth. Oxygen titrated to achieve SpO2 at 92 to 95%. After 24 hours, received conventional therapy Control group: Randomized, n = 77; losses, n = 0; analysed, n = 77 Details: oxygen after extubation via nasal prongs or facemask, regulated by Venturi. Oxygen titrated to achieve SpO2 at 92 to 95%. After 24 hours, continued to receive conventional therapy
Outcomes	Respiratory failure within 72 hours post‐extubation (NIV as rescue treatment was discouraged but given at discretion of attending team); reintubation; ICU and hospital lengths of stay; hospital mortality
Notes	Funding/declarations of interest: funding not reported. Two authors received conference fees or postdoctoral grant from Fisher & Paykel Healthcare Ltd. Study dates: 2013 to 2014 Note: study terminated early owing to low recruitment
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “Randomization was performed via a computerized random‐number table in blocks of four for each hospital”.
Allocation concealment (selection bias)	Low risk	Quote: "“allocation was concealed through numbered opaque envelopes”.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Blinding was not possible. Although we expected that this would not influence outcome data, we could not be certain of this.
Blinding of outcome assessors (objective outcomes)	Low risk	Blinding of outcome assessors is not described; we did not anticipate that this would influence the assessment of objective outcome measures
Incomplete outcome data (attrition bias) All outcomes	Low risk	No apparent losses
Selective reporting (reporting bias)	High risk	Study was prospectively registered with a clinical trials register (NCT01820507). We noted that some outcomes were reported in the published report but not listed in the trials register documents (hospital and ICU lengths of stay); this could indicate risk of selective reporting bias for these outcomes.
Other bias	Low risk	We identified no other sources of bias.