Oxygen Transport Agents: A New Approach to Red Blood Cell Alternatives

Abstract

Traditional approaches to red cell substitutes, including perfluorocarbon emulsions, modified hemoglobins or encapsulated hemoglobins, have not fulfilled their early promise. However, the vast amount of research performed in pursuit of these products has allowed a new and deeper insight into the details of O 2 transfer at the microscopic level and how red cells, hemoglobin and the vascular system interact to ensure tissue oxygenation. With this understanding in mind, it is now possible to design new O 2 carrier molecules specifically aimed at providing O 2 to hypoxic tissue. In one sense, these products are not “red cell substitutes” because many of their properties are different from those of red cells and simple measurement of hemoglobin concentration may not be the best indicator of their ability to effectively transport O 2 . More properly, these new molecules are “O 2 transport agents” and, as such, can be used in many clinical applications where red cells are administered today.