Krogh 1994.

Methods	Single‐centre RCT
Participants	Setting: a hospital in Odense, Denmark Inclusion criteria: ASA I‐II patients scheduled for elective major colonic surgery Participant numbers: 139 randomly assigned; 139 analysed
Interventions	Intervention: premedication comprised diazepam 0.2 mg/kg orally. Anaesthesia was induced with fentanyl 2 to 5 μg/kg intravenous. Propofol was given as a bolus dose of 1 mg/kg. All patients breathed 100% oxygen during induction. The patient's lungs were ventilated with oxygen via a face mask until the trachea had been intubated. Tracheal intubation was facilitated by administration of pancuronium 0.1mg/kg. Anaesthesia was maintained with fentanyl 2 to 4 μg/kg/h and propofol 1 to 2 mg/kg/h. The lungs of the patients were ventilated with nitrous oxide in oxygen. The inspiratory oxygen concentration was maintained at 30%. Neuromuscular block was maintained with pancuronium 1 to 2 mg if train‐of‐four showed one or two twitches. Before induction of anaesthesia, a lumbar extradural catheter was inserted and extradural bupivacaine given. Control: premedication comprised diazepam 0.2 mg/kg orally. Anaesthesia was induced with fentanyl 2 to 5 μg/kg intravenous. Propofol was given as a bolus dose of 1 mg/kg. All patients breathed 100% oxygen during induction. The patient's lungs were ventilated with oxygen via a face mask until the trachea had been intubated. Tracheal intubation was facilitated by administration of pancuronium 0.1mg/kg. Anaesthesia was maintained with fentanyl 2 to 4 μg/kg/h and propofol 4 to 6 mg/kg/h. The lungs of the patients were ventilated with oxygen and air. The inspiratory oxygen concentration was maintained at 30%. Neuromuscular block was maintained with pancuronium 1 to 2 mg if train‐of‐four showed one or two twitches. Before induction of anaesthesia, a lumbar extradural catheter was inserted and extradural bupivacaine given.
Outcomes	Secondary outcomes: Length of hospital stay
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	Unclear risk	This was not reported.
Blinding of outcome assessment (detection bias) Inhospital case fatality rate/length of stay	Low risk	The outcome measurement is not likely to be influenced by lack of blinding.
Blinding of outcome assessment (detection bias) Complications	Unclear risk	—
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.