ADVERSE-EFFECTS OF POSTOPERATIVE INFUSION OF SHED MEDIASTINAL BLOOD

Background. Postoperative infusion of shed mediastinal blood has been used in an effort to decrease blood usage after cardiac operations. Re cent experience has suggested that this practice may actually lead to a delayed increase in bleeding. Methods. In a prospective, randomized study, 40 patients undergoing coronary artery bypass grafting with she d mediastinal blood collected in a cardiotomy reservoir were divided i nto two equal groups and studied during their first 4 hours in the int ensive care unit. Shed mediastinal blood was directly infused in group I (n = 20), whereas in group II (n = 20), it was not. In group II, if a sufficient volume of red cells was present to allow processing (n = 5), washed red cells were infused. Variables studied before and after infusion were the amount of blood lost and infused, homologous blood transfused, complete blood count and differential, serum fibrinogen, f ibrin split products, D-dimers, clotting factors, prothrombin time, ac tivated partial thromboplastin time, thromboelastograms, plasma-free h emoglobin, complement factors C3 and C4, creatine kinase and its MB is oenzyme, and body temperature. Results. After infusion of shed mediast inal blood, elevated levels of fibrin split products and D-dimers were found in significantly more patients in group I. The thromboelastogra m index was normal in 76% of patients in group II but in only 12.5% in group I. Group I also had an increase in band neutrophils, a greater number of febrile patients, higher serum levels of creatine kinase, it s MB isoenzyme, and plasma-free hemoglobin, and greater blood loss dur ing hours 3, 4, and 5 in the intensive care unit. The volume of red ce lls in shed mediastinal blood (hematocrit, 9% to 10%) was small, resul ting in clinically insignificant autotransfusion when infused directly , and insufficient for cell processing in most patients. Conclusions. These data support those in previous studies that direct infusion of s hed mediastinal blood does not save substantial amounts of autologous red cells and can cause a delayed coagulopathy and other adverse effec ts that may be harmful to patients postoperatively.