Transfusion medicine

The era of modern transfusion medicine dates to the early twentieth century, with the identification of the blood groups A, B, and O by Landsteiner in 1901. Subsequent use of this technique for compatibility testing improved blood safety dramatically, although recognition of the immunologic diversity of red blood cells and sophisticated crossmatching had to await the discovery of the direct antiglobulin test for almost 50 years. The impact of a blood substitute in the developed world was initially in cases where red blood cells were not immediately available, such as in certain trauma cases and in patients for whom alloimmunization precludes location of adequately cross-matched blood. Blood substitutes could offer further advantages in added safety in regard to infection risk and more efficient delivery of oxygen to tissue. The potential for benefit in developing countries is especially promising, as many of these countries lack the sophisticated blood banking systems of the developed world, not to mention a reduced number of qualified donors. The full impact of a red blood substitute cannot be fully assessed until one or more products are available for clinical use, because any benefit will be balanced against any shortcomings such as side effects and limited intravascular persistence.