Comparison of transfusion requirements for conventional and miniaturized extracorporeal circuits

Hemodilution is a well-recognized phenomenon of cardiopulmonary bypass (CPB). The degree of hemodilution has attendant risks. As the degree of hemodilution increases, red blood cell transfusions may be necessary, and the risks of blood transfusions are becoming very well recognized. Blood-conservation programs are being developed worldwide to establish strategies to reduce transfusions. Miniaturized extracorporeal circuits (MECs) are associated with less hemodilution than conventional CPB circuits. The use of MECs can be expected to be associated with fewer red blood cell transfusions.

The first 250 patients who underwent coronary artery bypass grafting, aortic valve replacement, or both with the use of a MEC were compared with 200 consecutive patients who had similar comorbidities and types of surgery but underwent their operations on a conventional bypass circuit. These surgeries were completed between April 2004 and September 2005 under the care of the same surgical team. The minimum acceptable hematocrit on bypass was 22%. Intra- and postoperative transfusion rates were measured and compared.

For conventional bypass, the intraoperative transfusion rate was 36.5%, whereas the rate for the MEC was 23.3%. The postoperative transfusion rate was 55% for operations performed with conventional bypass and 26% for the MEC. The overall in-hospital transfusion rate for conventional bypass was 63% and 36% for the MEC.

The data indicate that use of MECs leads to a lower transfusion rate than in surgeries in which conventional CPB is used.