Blood replacement in dogs by dextran-hemoglobin.

Exchange transfusions in dogs were performed with a solution of either dextran or a covalent complex between dextran and human hemoglobin. Dogs transfused with dextran alone died when their hematocrit was lowered to 6-10%. Dogs transfused with dextran-hemoglobin complex, however, survived a reduction of their hematocrit to 2% or below. In the latter animals, the dextran-hemoglobin complex disappeared from the circulation with an average half-life of 2.4 days. Correcting for oxidation of the hemoglobin moiety to methemoglobin, the half-life of functional unoxidized dextran-hemoglobin in the circulation was 1.9 days. In compensation for the loss of dextran-hemoglobin, vigorous erythropoiesis was observed at a rate of close to 5% hematocrit per day over the first 2 days following the exchange transfusion. As a result, the total hemoglobin concentration in blood was maintained at 5-6% during this period, and the animals went on to complete recovery in room air without the need for further transfusion with dextran-hemoglobin.