Klein 2008.

Study characteristics
Methods	Design: RCT, parallel two‐arm, single‐centre study Setting: specialist cardiothoracic hospital, Papworth, Cambridgeshire, UK Recruitment: recruitment and study dates not specified Maximum follow‐up: 5 days postoperatively
Participants	213 participants undergoing first‐time CABG and/or cardiac valve surgery were randomised to one of two groups: Cell salvage group: N = 102. M:F 78:24. Mean (SD) age 68.6 (9.6) Control group: N = 111. M:F 84:27. Mean (SD) age 67.4 (10.2). There were no differences between the groups with regard to demographic and preoperative variables.
Interventions	Cell salvage group: the cell salvage group (C.A.T.S. Fresenius Hemocare system) had their suctioned blood processed before and after CPB with the cell salvage apparatus. After weaning from CPB, blood remaining in the CPB circuit was processed by the cell saver device. All recovered blood, with no minimum volume due to the design of the cell salvage device, was transfused to the patient. Postoperatively, the cell saver was transferred with the patient to the intensive care unit (ICU) and connected to the chest tubes. All blood lost during the first 6 hours was processed and autotransfused. Cell salvage was disconnected after 6 hours. Control group: in the control group, blood suctioned before and after CPB discarded. After CPB, any remaining blood in the bypass machine tubing and reservoir was collected in the bag and transfused directly to the patient.
Outcomes	Primary outcome: number of participants transfused allogeneic blood Secondary outcomes: amount of allogeneic blood transfused, number of participants transfused fresh frozen plasma, number of participants transfused platelets, blood loss, adverse events, re‐operation for bleeding
Notes	Transfusion protocol: during surgery, allogeneic RBCs were transfused for a haemoglobin 7.0 g/dL. Postoperatively, allogeneic RBCs were transfused for haemoglobin 8.0 g/dL. In the cell salvage group, allogeneic blood was only transfused if there were no available RBCs from the cell salvage processing. Prospective registration status: the study was published prior to 2010. Ethical approval: the study was approved by a research ethics committee (05/Q0106/19). Language of publication: English Trial funding: funded in part by autotransfusion device manufacturer (Fresenius, C.A.T.S. manufacturer) via unrestricted educational grant and in part by anaesthetic research unit at Papworth Hospital. Conflicts of interest: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were allocated to intervention or control by simple randomisation generated by an independent statistician using a computer random number function, stratified by type of surgery.
Allocation concealment (selection bias)	Low risk	The randomised allocation was performed on admission to hospital the day before surgery and held in the hospital research unit until the participant had consented and was registered.
Blinding of participants and personnel (performance bias) Objective outcome: mortality	Low risk	No objective outcomes reported (mortality unlikely to be affected by blinding if reported in future publications)
Blinding of participants and personnel (performance bias) Subjective: transfusion protocol	Low risk	Transfusion protocol in place: during surgery, allogeneic RBCs were transfused for haemoglobin 7 g/dL. Postoperatively, allogeneic RBCs were transfused for haemoglobin 8.0 g/dL. In the cell salvage group (see below), allogeneic blood was only transfused if there were no available RBCs from the cell salvage processing.
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	High risk	No blinding: due to the nature of the intervention, group allocations were necessarily made available to operating room and intensive care unit (ICU) staff managing the participants.
Blinding of outcome assessment (detection bias) Objective outcomes: mortality and transfusions	Low risk	No objective outcomes reported (mortality unlikely to be affected by blinding if reported in future publications)
Blinding of outcome assessment (detection bias) Subjective outcomes	High risk	No blinding: due to the nature of the intervention, group allocations were necessarily made available to operating room and intensive care unit (ICU) staff managing the participants.
Incomplete outcome data (attrition bias) All outcomes	Low risk	The total number of participants contributing to the outcome measures is not reported, but an intention‐to‐treat analysis was performed.
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Unclear risk	Funded in part by autotransfusion device manufacturer via unrestricted educational grant. No baseline imbalance