Short 1985.

Methods	Single‐centre RCT
Participants	Setting: a hospital in London, UK Inclusion criteria: ASA I‐III patients scheduled for either minor gynaecological procedures such as dilatation and curettage, or urological procedures such as cysto‐urethroscopy Exclusion criteria: surgery lasted less than 30 minutes; alternative anaesthetic techniques were required; use of opioids for postoperative pain relief Participant numbers: 60 randomly assigned; 47 analysed
Interventions	Intervention: two anaesthetic protocols were used for induction and maintenance of anaesthesia. In protocol 1, patients received alfentanil 5 μg/kg over 1 minute, followed by methohexitone 1.5 mg/kg. The patients then breathed nitrous oxide and oxygen (FiO2 = 0.3). Supplements of alfentanil 2.5 μg/kg were given every 8 minutes until cessation of surgery, and increments of methohexitone 20 mg were given as clinically required. In protocol 2, patients received methohexitone 1.5 mg/kg as induction, followed by up to 5% isoflurane with 66% nitrous oxide in oxygen via a Magill system. When anaesthesia was satisfactory, the isoflurane concentration was decreased to 1.5 to 2%. Control: patients received methohexitone 1.5 mg/kg as induction, followed by up to 5% isoflurane in oxygen via a Magill system. When anaesthesia was satisfactory, the isoflurane concentration was decreased to 1.5 to 2%.
Outcomes	Secondary outcomes: Severe nausea and vomiting: no specific definition
Notes	The results from 13 patients were excluded from the study because either surgery lasted more than 30 minutes, or alternative anaesthetic techniques were required, such as tracheal intubation or the use of opioids for postoperative pain relief.
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	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	High risk	Quote: "The observer was aware of which anaesthetic had been used."
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Insufficient information.
Selective reporting (reporting bias)	Low risk	All outcomes described in methods section reported.
Other bias	High risk	Fewer than 50 participants per arm.