Methods	A prospective randomised clinical trial was undertaken to compare the current approach of mediastinal drainage without reinfusion to a system specifically designed for reinfusion. From September 1998 to January 1999, patients admitted for coronary artery bypass grafting operations, valvular replacement, or both procedures under cardiopulmonary bypass (CPB) were offered the option to participate in the study. Method of randomisation and allocation concealment were not described
Participants	198 patients undergoing cardiac surgery were randomised to one of two groups: Group 1 (Autotransfusion group): n=98; M//F= 75//23; mean (sd) age = 62 (19.8) years Group 2 (Control group): n=100; M//F=70/30; mean (sd) age = 66 (20.0) years
Interventions	Group 1: Autotransfusion group were treated with an autotransfusion system (Atrium Medical Corporation) consisting of 28F thoracic tubes connected to a three chamber system. All collected blood was filtered and autotransfused until no drainage was present or for a maximum period of 12 hours. Transfusion began one hour after the patient arrived in the Intensive Care Unit (ICU). Group 2: Control group had their post-operative mediastinal drainage discarded.
Outcomes	Outcomes reported: number of patients transfused allogeneic blood, amount of allogeneic blood transfused, blood loss, adverse events
Notes	Transfusion threshold: during CPB allogeneic red blood cells were transfused for haemoglobin concentrations below 6.0g/dL. In the post-operative period the threshold for allogeneic red blood cell transfusion was Hb<8.0g/dL
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 was unclear.
Blinding (performance bias and detection bias) All outcomes	High risk