Nishikawa 2004.

Methods	RCT, parallel design, single‐centre
Participants	Total number of randomized participants: 50 Inclusion criteria ASA I or II, > 65 years of age, scheduled for elective laparoscope‐assisted surgical procedures which would last > 3 hours, under combined GA and epidural anaesthesia Exclusion criteria People with anticoagulation, symptomatic coronary artery disease, cardiac valvular regurgitation or stenosis, central nervous system or neuromuscular disorders Major or minor tranquillizer medication Psychotic symptoms or cognitive impairment as judged by a psychiatrist Type of surgery: laparoscopic surgery (choledocholithotomy, colectomy, sigmoidectomy) Baseline characteristics TIVA group Age, mean (SD): 71 (± 8) years Gender, M/F: 13/12 ASA grade: ASA I: 7; ASA II: 18 Inhalational maintenance group Age, mean (SD): 71 (± 7) years Gender, M/F: 12/13 ASA grade: ASA I: 6; ASA II: 19 Country: Japan Setting: hospital
Interventions	TIVA group Participants: n = 25; 0 losses Induction details: 100% O2 via face mask for 3 minutes prior to induction. Induction with propofol using 4 µg/mL TCI. Use of 2% lidocaine solution for injection pain Maintenance details: 4 µg/mL propofol TCI. Study authors report mean (SD) range of 1.2 (± 0.2) µg/mL to 2.7 (± 0.2) µg/mL propofol. Use of clinical signs to maintain anaesthesia Additional regional anaesthesia: epidural anaesthesia: 6 mL to 8 mL of 1.5% lidocaine, followed by continuous epidural administration at a rate of 4 mL/hour to 6 mL/hour throughout surgery Inhalational maintenance group Participants: n = 25; 0 losses Induction details: 100% oxygen via face mask for 3 minutes prior to induction. 5% sevoflurane and 100% oxygen at 6 L/min until inspired limb‐drug concentration was > 4%. Vecuronium 0.1 mg/kg. Maintenance details: sevoflurane with O2/air mix at total gas flow of 3 L/min. Vecuronium 1 mg to 2 mg IV boluses as required. Study authors report mean (SD) range of 0.9% (± 0.1%) to 1.7% (± 0.4%) sevoflurane
Outcomes	Duration of anaesthesia Duration of surgery Intraoperative complications (hypotension, bradycardia, hypertension, tachycardia, increased salivation) Postoperative delirium (using DRS) Pain (using VAS)
Notes	Funding/declarations of interest: not reported Study dates: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Participants were "randomly assigned by a sealed envelope technique". Insufficient information
Allocation concealment (selection bias)	Unclear risk	Described as "randomly assigned by a sealed envelope technique". Insufficient information
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not feasible to blind anaesthetists to intervention groups
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Delirium was assessed by a psychiatrist blinded to intervention group. Data on emergence times was assessed by a nurse who was blinded to intervention group.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No apparent loss of study participants
Selective reporting (reporting bias)	Unclear risk	Study authors do not report clinical trials registration. Not feasible to judge risk of selective outcome reporting
Other bias	Low risk	No other source of bias identified