Additional postoperative cell salvage of shed mediastinal blood in cardiac surgery does not reduce allogeneic blood transfusions: a cohort study

Objectives: Does additional postoperative collection and processing of mediastinal shed blood with a cell salvage device reduce the number of allogeneic blood transfusions compared to intraoperative cell salvage alone? Methods: A single-centre cohort study in which adult patients with coronary artery bypass grafting or aortic valve replacement were allocated to either a C.A.T.S-(R) group with intraoperative blood processing only or a CardioPat((R)) group with both intra- and postoperative blood processing. The primary endpoint was the number of allogeneic blood transfusions during hospital admission. Results: The study included 99 patients; 50 in the C.A.T.S-(R) and 49 in the CardioPat((R)) group. There was no difference in the number of red blood cells (RBC) (C.A.T.S-(R) group 43 units versus CardioPat((R)) 50 units, p=0.74), fresh frozen plasma (C.A.T.S-(R) 8 units versus CardioPat((R)) 8 units, p=1.00) or platelets (C.A.T.S-(R) 5 units versus CardioPat((R)) 4 units, p=1.00) transfused during the hospital stay. Cardiac creatinine kinase (CK-MB) and troponin levels did not differ between the groups although a significant time effect (p<0.001) was present. Creatinine kinase (CK) levels were not different between the groups three hours after arrival in the intensive care unit (ICU) (CardioPat((R)) group versus C.A.T.S-(R) group, p=0.17). But, compared to the C.A.T.S-(R) group on the first (350 [232-469] IU/L) and second postoperative days (325 [201-480] IU/L), the increase in CK levels was more in the CardioPat((R)) group on the first (431 [286-642] IU/L, p=0.02) and second postoperative days (406 [239-760] IU/L, p=0.05), resulting in a difference between the groups (p=0.04) Conclusions: Postoperative cell salvage does not reduce transfusion requirements compared to intraoperative cell salvage alone, but results in elevated total CK levels that suggest haemolysis.