Autotransfused shed mediastinal blood has normal erythrocyte survival

Background. Autotransfusion of shed mediastinal blood may reduce the need for homologous blood transfusions in cardiac surgery. In an earlier study we have shown that the red blood cells (RBCs) of shed mediastinal blood have a normal membrane stability (osmotic fragility) compared with circulating RBCs after coronary artery bypass grafting and better than stored RBCs. This indicates that RBCs in shed mediastinal blood are not damaged further during salvage. It remains to be determined how autotransfusion affects the survival of RBCs from shed mediastinal blood. Methods. We performed a prospective, randomized, and controlled study involving 26 patients having elective, uncomplicated coronary artery bypass grafting. Dual-isotope labeling technique (chromium 51 and technetium 99m) was used to investigate the 24-hour survival of RBCs from shed mediastinal blood and RBCs from circulating blood, and to estimate the mean survival time of RBCs. Results. There was no significant difference between the 24-hour survival of shed mediastinal RBCs and circulating RBCs. The estimated mean cell lifespan was 20.5 days (range, 11.6 to 29.0 days) for shed mediastinal RBCs and 22.7 days (range, 14.4 to 36.2 days) for circulating RBCs. Conclusions. The survival of RBCs from shed mediastinal blood after autotransfusion is comparable with the survival of RBCs in the patientsʹ circulating blood.