Effects on complement activation of a new continuous autotransfusion system

Allogeneic blood transfusions may subject patients to risks of infection and allergic reactions. Various techniques for transfusion of shed blood have been developed. The aim of this study was to evaluate a new continuous autotransfusion system (Fresenius CATS^®) as regards its impact on the complement system, and on erythrocytes and leucocytes. Eighteen consecutive patients undergoing hip replacement surgery were studied. Complement variables (C4d, factor Bb, C3a and terminal complement complex, SC5b-9) and free haemoglobin, haemoglobin, leucocytes, platelets, albumin and protein were determined in the patient's blood preoperatively, 1 min before the start of transfusion, 15 and 60 min after transfusion; and in the reservoir, in the waste bag and in the retransfusion blood. Increased concentrations of C3a and SC5b-9 were found in the collected reservoir blood ( P  < 0.05). The washing and centrifugation procedure reduced these concentrations (< 0.001). High levels of free haemoglobin were found in the collected blood as well as in the processed product. The median haemoglobin level in the processed blood was 260 g L⁻¹ (range 104–289 g L⁻¹). Inflammatory mediators from the complement cascade are removed by continuous autotransfusion technique. The processed blood contains high levels of free haemoglobin.