Autologous transfusion of shed mediastinal blood after coronary artery bypass grafting and bacterial contamination

Background. Autologous transfusion of shed mediastinal blood is often used after coronary artery bypass grafting (CABG). Shed blood has in a few studies been cultured during the first postoperative hours. However, autologous transfusion might in some cases be continued for several hours and no study has yet examined the bacterial contamination of shed blood later than 6 hours postoperatively. Methods. Seventy-five patients undergoing electively performed CABG were included. Cultures of shed blood were taken at initiation of the autologous transfusion and the following morning. Infection variables were measured preoperatively and postoperatively. Infectious complications during the first postoperative week were registered. Results. The frequency of patients with bacterial growth in the first culture was 0.22 (95% confidence interval: 0.12 to 0.31) compared with 0.04 (95% confidence interval: −0.044 to 0.087) in the second culture (p < 0.002). We found no significant difference in infection variables between patients with or without bacterial growth in the cultures. No patients suffered from early postoperative infectious complications. Conclusions. There is no further contamination of the shed blood during the period between initiating the autologous transfusion and the following morning.