There is no true substitute for the many functions of human red blood cells, and synthetic products will not replace the need for blood donation in the foreseeable future. Hemoglobin-based oxygen carriers have many characteristics that would serve as a useful adjunct to red cells in clinical settings. Over time, these technologies have the potential to dramatically reshape the practice of transfusion medicine.
To review the characteristics and potential utility of hemoglobin-based oxygen carriers and perfluorocarbon-based oxygen carriers. Several hemoglobin-based oxygen carriers are under study in phase III clinical trials. Novel uses for synthetic oxygen therapeutics are emphasized.
All published reports with the key words oxygen therapeutics, blood substitutes, and red cell substitutes from 1933 until March 2006 were searched through Medline. Significant findings were synthesized.
Recognition of the true impact of red cell substitutes is still several years away. The most compelling products, hemoglobin-based oxygen carriers, have potential use in trauma, providing immediate oxygen-carrying support in the face of alloantibodies or autoantibodies, and in other clinical situations in which long-term survival of red cells is not essential. In the interim, efforts should be focused on enhancing the current blood supply system while supporting ongoing and planned blood substitute research efforts, including trials assessing novel clinical indications for these products.