Schmidt 1996.

Methods	Between November 1992 and October 1993, adult patients undergoing primary elective coronary artery bypass grafting entered the prospective, randomised, controlled study. Method of randomisation was not described. Allocation concealment was by means of sealed envelopes.
Participants	120 adult patients undergoing primary elective coronary artery bypass grafting were randomly allocated to one of two groups: Group 1 (Autotransfusion group): n=53; M/F=46/7; mean (sd) age = 58.5 (7.4) years Group 2 (Control group): n=56; M/F=51/5; mean (sd) age = 57.5 (8.9) years
Interventions	Group 1: Autotransfusion group had at the end of the operation, the mediastinal and pleural tubes attached to the inlet port of the Bard cardiotomy/autotransfusion reservoir. Shed mediastinal blood from the cardiotomy reservoir was transfused every hour for the first 18 post‐operative hours if more than 20mls of blood had accumulated. Prior to transfusion the shed mediastinal blood was filtered through a 40um filter in the cardiotomy reservoir. Group 2: 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 patients transfused allogeneic blood, adverse events, sternal infections, myocardial infarction, sepsis, mortality, blood loss.
Notes	Transfusion threshold: patients were transfused allogeneic blood if the haemoglobin concentration was less than 5.0mmol/L in the intensive care unit and less than 5.5mmol/L during the rest of the hospital stay.
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)	High risk	Method used to conceal treatment allocation was inadequate.
Blinding (performance bias and detection bias) All outcomes	High risk