Brodsky 2005.

Methods	Single‐centre RCT
Participants	Setting: Stanford University Medical Center, USA Inclusion criteria: patients undergoing either laparoscopic Roux‐en‐Y gastric bypass or gastric banding operations Participant numbers: 50 randomly assigned; 50 analysed
Interventions	Intervention: the lungs of patients were ventilated with the volatile anaesthetic, oxygen (50%) and nitrous oxide (50%). Control: the lungs of patients were ventilated with the volatile anaesthetic, oxygen (50%) and air.
Outcomes	Other outcomes: Quality of recovery
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "A randomization table was used to assign each patient to one of two groups."
Allocation concealment (selection bias)	Unclear risk	No details given.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	This was not reported.
Blinding of outcome assessment (detection bias) Inhospital case fatality rate/length of stay	Unclear risk	—
Blinding of outcome assessment (detection bias) Complications	Low risk	Quote: "The surgeon was blinded as to whether the patient was receiving air or nitrous oxide, was asked whether nitrous oxide was being used."
Incomplete outcome data (attrition bias) All outcomes	Low risk	No missing data.
Selective reporting (reporting bias)	Low risk	All outcomes described in methods section reported.
Other bias	Low risk	No other potential sources of bias were detected.