Unsworth 1996.

Study characteristics
Methods	Design: RCT, parallel three‐arm, single‐centre study Setting: university teaching hospital, London, UK Recruitment: recruitment and study dates not reported Maximum follow‐up: not reported
Participants	105 participants undergoing primary elective coronary artery bypass graft surgery were randomised to one of three groups: Group 1 (No autotransfusion) (Control/no cell salvage group): N = 34. M:F 30:4. Median (range) age 63 (58 to 67) Group 2 (Autotransfusion group ‐ uncoated circuit) (cell salvage/intervention group): N = 36. M:F 30:6. Median (range) age 64 (58 to 67) Group 3 (Autotransfusion group ‐ heparin‐coated circuit) (cell salvage/intervention group): N = 35. M:F 31:4. Median (range) age 62 (55 to 67) years The groups were comparable at baseline assessment.
Interventions	Group 1 (No autotransfusion) (Control/no cell salvage group): control group had their chest drains connected to underwater sealed drainage bottles with suction applied at 10 kilopascal (kPa). Autotransfusion was not performed. Group 2 (Autotransfusion group ‐ uncoated circuit) (cell salvage/intervention group): autotransfusion group (uncoated circuit) had their chest drains connected to a cardiotomy reservoir (CATR 3500) to which suction at 10 kPa was applied. This reservoir contained a 20 µm filter which removed debris and clots from the drained blood. From there, blood was carried via an infusion pump which incorporated an air‐in‐line detector to a peripheral line. Autotransfusion commenced when there was > 100 mL in the cardiotomy reservoir and continued thereafter for 10 hours. Infusion was in hourly pulses according to the previous hour's drainage. Group 3 (Autotransfusion group ‐ heparin‐coated circuit) (cell salvage/intervention group): autotransfusion group (heparin‐coated circuit) had the autotransfusion circuit bonded with heparin. The heparin‐bonded circuit comprised an identical system of drains and tubes except that all surfaces, including the cardiotomy reservoir and connector but excluding the piston chamber of the infusion pump and the intravenous cannula, were coated with heparin by the Duraflow II methodology.
Outcomes	Outcomes reported: amount of blood re‐transfused from the cell saver, amount of allogeneic blood transfused, number of participants receiving allogeneic blood, adverse events, re‐exploration for bleeding, blood loss, mortality
Notes	Transfusion protocol: allogeneic blood was transfused to maintain the haematocrit level > 25%. Prospective registration status: the study was published prior to 2010. Ethical approval: the study was approved by the Ethics Committee of St George's Hospital. Language of publication: English Trial funding: British Heart Foundation, British Cardiac Society Conflicts of interest: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A computer randomisation program. This program minimised differences between groups in age, sex, body surface area, aspirin ingestion within a week of surgery, and surgeon.
Allocation concealment (selection bias)	Unclear risk	Method used to conceal treatment allocation was unclear.
Blinding of participants and personnel (performance bias) Objective outcome: mortality	Low risk	Objective outcome (mortality) unlikely to be influenced by blinding
Blinding of participants and personnel (performance bias) Subjective: transfusion protocol	Low risk	Transfusion protocol in place: homologous blood was transfused to maintain the haematocrit > 25%.
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	Low risk	No blinding mentioned, but appears that all outcomes measured had protocols or were objectively measured
Blinding of outcome assessment (detection bias) Objective outcomes: mortality and transfusions	Low risk	Objective outcome (mortality) unlikely to be influenced by blinding
Blinding of outcome assessment (detection bias) Subjective outcomes	High risk	The blinding status of outcome assessors was not described. Outcome measures not clearly defined
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants randomised are accounted for in the reported outcomes, appears to be ITT
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Low risk	No baseline imbalance. Funding reported (non‐pharmaceutical)