Lindwall 1998.

Methods	Design: RCT Operative phase:intraoperative Withdrawals: 3/28 (11%) Setting: 1 centre (Sweden) Sample size: 25 Funding: not stated
Participants	Age (mean range): 65 ‐ 66 years Gender (M/F): not stated ASA grade: I ‐ IV Surgery type: elective (extensive thoracoabdominal surgery: oesophageal, rectal or bladder carcinoma) Surgery duration (mean range): > 2 hrs (280/287 mins) Anaesthesia type: general and regional
Interventions	Intervention (ABSW): n = 12 Upper or lower forced‐air warming (Bair Hugger®, Model 500, Augustine Medical, USA) Duration: started before induction of anaesthesia and stopped at end of operation Temperature setting at 43°C (SD 2.3) Body area covered: upper or lower body Proportion covered: 30% ‐ 40% Control: n = 13 Standard passive management consisting in insulation with double layers of terry cloth plus operation drapes covering the whole body Duration: not stated Temperature setting at 39°C Co‐interventions: Active fluid warming in both groups (38° – 39°C) Room temperature: 22ºC
Outcomes	Blood loss (ml) Other outcomes reported not included in the review: Continuing thoracic epidural analgesia
Notes	Comparison 1
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not reported
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not reported
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported
Baseline comparability of groups	Low risk	To a high extent according to Table 1
Co‐interventions equal between groups	Unclear risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	3 participants withdrawn from the study because they did not fulfill the inclusion criteria
Selective reporting (reporting bias)	Unclear risk	We did not have access to the protocol, therefore we cannot exclude risk of selective reporting with the information provided
Other bias	Low risk