Sukhani 1994.

Methods	Single‐centre RCT
Participants	Setting: Loyola University Medical Center, USA Inclusion criteria: nonpregnant patients, 19 to 40 years of age, ASA I‐II, scheduled for ambulatory gynaecologic laparoscopy Exclusion criteria: patients were excluded from the study if they weighed more than 150% of their ideal body weight or had predisposing factors for delayed gastric emptying, such as diabetes, chronic cholecystitis, scleroderma, neuropathies, and neuromuscular disorders. Patients who demonstrated significant anxiety and who, in the anaesthesiologist's judgment, required preoperative anxiolytic therapy were also excluded Participant numbers: 70 randomly assigned; 70 analysed
Interventions	Intervention: patients were ventilated with a mixture of oxygen and nitrous oxide and the inspired oxygen concentration was maintained at 30%. Control: patients were ventilated with a mixture of oxygen and air and the inspired oxygen concentration was maintained at 30%.
Outcomes	Other outcomes: Quality of recovery
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as randomized but no further details.
Allocation concealment (selection bias)	Unclear risk	No details given.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote: "The patients were assigned using a non‐blinded study design."
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: "Intermediate recovery variables were recorded by recovery room nurses and the attending anaesthesiologist blinded to anaesthetic technique."
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.