Yu 2017.

Study characteristics
Methods	RCT, parallel‐group design. Multicentre study
Participants	Total number of randomized participants: 110 Setting: ICUs in 3 hospitals; China Inclusion criteria: undergoing planned thoracoscopic lobectomy because of lung tumour, and at intermediate or high risk for postoperative pulmonary complications Exclusion criteria: immunocompromised; pregnant; converted to an open thoracotomy because of poor visualization or bleeding; < 18 or > 80 years of age; informed consent could not be obtained Baseline characteristics: Intervention group (HFNC): Age, mean (SD): 56.31 (± 7.03) years Gender, M/F: 30/26 BMI, mean (SD): 26.32 (± 4.73) kg/m2 APACHE II, mean (SD): 26.32 (± 4.73) PaCO2, mean (SD): 41.73 (± 6.33) mmHg PaO2/FiO2, mean (SD): 350.35 (± 33.87) mmHg Respiratory rate, mean (SD): 18.43 (± 3.45) breaths/min Control group (standard oxygen therapy): Age, mean (SD): 55.82 (± 7.92) years Gender, M/F: 28/26 BMI, mean (SD): 25.19 (± 5.02) kg/m2 APACHE II, mean (SD): 25.19 (± 5.02) PaCO2, mean (SD): 43.52 (± 4.93) mmHg PaO2/FiO2, mean (SD): 340.98 (± 40.65) mmHg Respiratory rate, mean (SD): 17.98 (± 3.87) breaths/min
Interventions	Intervention group (HFNC): Randomized, n = 56; losses, n = 0; analysed, n = 56 Details: after extubation, after tolerating SBT, HFNC delivered by Optiflow (using MR850 heated humidifier and RT202 breathing circuit) with flow rate of 35 to 60 L/min, FiO2 titrated by treating clinician to maintain SpO 2 ≥ 95% Control group: Randomized, n = 54; losses, n = 0; analysed, n = 54 Details: after extubation, after tolerating SBT, oxygen delivered via nasal prongs or facemask with oxygen flow titrated by treating clinician to maintain SpO2 ≥ 95%
Outcomes	Incidence of hypoxaemia in first 72 hours after extubation; PaO2; PaO2/FiO2, SpO2/FiO2, and PaCO2; postoperative pulmonary complications (pneumonia and atelectasis); AHRF (for which participants were initially given NIV with BiPAP and, if required, were then reintubated); adverse effects (air leak, throat or nasal pain, abdominal distension); mortality; length of ICU and hospital stay; total hospitalization expenditure Note: we did not include data for arterial gases in the review, because study authors presented these data in figures that we could not clearly interpret as numerical data.
Notes	Funding/declarations of interest: funding not reported. Study authors declared no competing interests. Study dates: January 2015 to June 2016
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomization using STATA statistical package
Allocation concealment (selection bias)	Unclear risk	No details
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 was not described; we did not anticipate that this would influence the assessment of objective outcome measures.
Blinding of outcome assessors (subjective measures)	Low risk	Blinding of outcome assessors was not described; we did not anticipate that this would influence the assessment of subjective outcome measures.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No participant losses
Selective reporting (reporting bias)	Unclear risk	Study authors did not report clinical trials registration or a prepublished protocol. It was not feasible to effectively assess risk of selective reporting bias without these documents.
Other bias	Low risk	We identified no other sources of bias.