Schmidt 1996.

Study characteristics
Methods	Design: RCT, parallel two‐arm, single‐centre study Setting: university teaching hospital, Copenhagen, Denmark Recruitment: November 1992 to October 1993 Maximum follow‐up: not reported
Participants	120 adult participants undergoing primary elective coronary artery bypass grafting were randomly allocated to one of two groups: Autotransfusion group (Cell salvage/intervention group): N = 53. M:F 46:7. Mean (SD) age 58.5 (7.4). Mean (SD) weight 82.5 (10.2) kg Control group: N = 56. M:F 51:5. Mean (SD) age 57.5 (8.9). Mean (SD) weight 85.0 (12.7) kg There was no difference between the groups with regard to baseline demographic variables.
Interventions	Autotransfusion group: cell salvage group had the mediastinal and pleural tubes attached to the inlet port of the Bard cardiotomy/autotransfusion reservoir at the end of the operation. Blood collected in the CPB circuit at the conclusion of CPB was collected for later transfusion. Shed mediastinal blood from the cardiotomy reservoir was transfused every hour for the first 18 postoperative hours if > 20 mL of blood had accumulated. Prior to transfusion, the shed mediastinal blood was filtered through a 40 µm filter in the cardiotomy reservoir. Control group: control group had the cardiotomy reservoir used for mediastinal drainage only. Autotransfusion was not performed.
Outcomes	Outcomes reported: amount of blood re‐transfused from the cell saver, amount of allogeneic blood transfused, number of participants transfused allogeneic blood, adverse events, sternal infections, myocardial infarction, sepsis, mortality, blood loss
Notes	Transfusion protocol: participants were transfused allogeneic blood if the haemoglobin concentration was < 5.0 mmol/L in the intensive care unit and < 5.5 mmol/L during the rest of the hospital stay. Prospective registration status: the study was published prior to 2010. Ethical approval: the study was approved by the regional ethics committee. Language of publication: English Trial funding: not reported Conflicts of interest: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method used to generate allocation sequences was not described.
Allocation concealment (selection bias)	Unclear risk	Method used to conceal treatment allocation is unclear.
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: Hb < 5 mmol/L in ICU, or Hb < 5.5 mmol/L in surgical ward
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	Low risk	Randomisation in ICU (postoperatively), therefore no performance bias likely
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	Unclear risk	The blinding status of outcome assessors was not described, and some outcome variables are not defined
Incomplete outcome data (attrition bias) All outcomes	High risk	Five participants with significant postoperative events were excluded from the study following randomisation. 120 randomised, 109 analysed. 11 reasons given for exclusion (only 3 were valid for technical failures)
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Unclear risk	No baseline imbalance. No funding or conflicts reported