Theoretical evaluation of expected changes in oxygenation of tumors associated with different hemoglobin levels

A mathematical computer-based model was developed which analyzes the influence of hemoglobin concentration; shape of the oxygen dissociation curve; red cell velocity; capillary network geometry; and oxygen consumption on the oxygen partial pressure (PO2) distribution in tissue. In this study, the influence of acute hemoglobin concentration changes on the oxygen supply to tissue was analyzed. The specific question, whether moderate changes in the hemoglobin concentration of only 20% (e.g., from 15 g/dl to 12 g/dl i.e. baseline is 15 g/dl), as they may often occur clinically, are able to produce a significant change in the tissue oxygenation, was addressed. This is of importance for the estimation of the possible effects of blood transfusions prior to radiation therapy. The model predicts that even a moderate 20% increase in the hemoglobin concentration is able to decrease the anoxic tissue volume by 30%. The results indicate that hemoglobin levels should not be subnormal at the beginning of chemotherapy or radiotherapy. Transfusions or the application of artificial oxygen carriers could be helpful.