Processing small volumes in blood salvage: Characterization of ELECTA, CATS and OrthoPAT

Background: New technical developments such as a small Latham-bowl, a continuous autotransfusion system and a handy device with dynamic disc designed for postoperative autotransfusion raise hopes for a possible application of blood salvage in young children. However, the minimal blood volume for effective processing under clinically relevant conditions has yet to be determined. Methods: Fresh blood from volunteer donations with a haematocrit of 10% was used to test ELECTA (Sorin) equipped with a 55ml bowl, CATS (Fresenius) in the paediatric program mode, and OrthoPAT (Haemonetics). 20 ml portions of RBC were added and processed under various conditions, including clinically relevant first filling and intermittent emptying. RBC recovery and plasma elimination were calculated from the haematocrit and free haemoglobin and total protein. Results: The main impediment to recovery and availability is the first filling. There, RBC recovery was significantly reduced, while it subsequently varied between 86 and 96%. To produce the first 30ml of RBC ELECTA required 42ml, CATS and OrthoPAT 62ml owing to the dead space of the separation chamber or the reservoir, respectively. RBC availability was much higher in the subsequent processes, with only minimal differences between the three devices. They all consistently provided high plasma elimination rates. Conclusions: A loss of 30-40% of the estimated blood volume must be tolerated by a young child or infant before enough autologous blood for a relevant transfusion (10% of its blood volume) can be made available. All three devices are suitable for the processing of small volumes, but all three have the scope for further optimization.