Hemoglobin solutions as red cell substitutes.

Hemoglobin solutions have potential as temporary red cell substitutes. Their efficacy has been demonstrated by their ability to maintain life-supporting levels of O2 consumption and CO2 production in animals virtually free of red cells. They do not exhibit major toxic effects, but transient alterations in renal function remain a concern. Cardiac output does not increase in the face of acute anemia associated with isovolemic exchange transfusion with hemoglobin solution. However, cardiac reserve does not diminish significantly after infusion of hemoglobin solution. Alterations in production techniques may lead to a polymerized hemoglobin solution that has a hemoglobin concentration and P50 close to fresh whole blood. Though this development is encouraging, it is clear that no perfect red cell substitute currently is available.