Dramis 2006.

Methods	Patients undergoing primary unilateral total knee arthroplasty over a consecutive 30‐day period were studied to assess the efficacy and financial cost of post‐operative reperfusion of drained blood.
Participants	49 patients undergoing primary unilateral total knee arthroplasty were randomly allocated to one of two groups: Group 1 (Autotransfusion group): n=32; M/F=11/21; mean (range) age = 69 (49‐83) years Group 2 (Control group): n=17; M/F=4/13; mean (range) age = 72 (62‐91) years
Interventions	Group 1: Autotranfusion group (CellTrans system) had their drained blood filtered through a 40um filter before being reinfused. Before closure of the wound two drainage tubes were inserted. The tubes were connected through a Y‐connector to the CellTrans assembly which contains two transfusion bags. The clamps remained closed for 20 minutes after the wound had been closed off. The drainage was started in the recovery room and collected for 6 hours or until 600mls of blood had accumulated at which point reinfusion took place. Collection up to a maximum of 12 hours ‐ thereafter the blood collected in the drains was discarded. Group 2: Control group received a standard vacuum drain (Redivac high vacuum drainage system). Drains were removed routinely at 48 hours. Contents were discarded.
Outcomes	Outcomes reported: number of patients transfused allogeneic blood, amount of allogeneic blood transfused, Hb levels, cost.
Notes	Transfusion threshold: the trigger for transfusing allogeneic blood was a post‐operative haemoglobin level of less than 9.0g/dL or clinical symptoms of anaemia.
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