A double (exchange transfusion-carbon clearance) model for testing post-resuscitation reticuloendothelial function

A double exchange transfusion-double carbon clearance method was evaluated for assessing reticuloendothelial (RE) function following exchange transfusion with hemoglobin solutions. Fifty percent of estimated blood volume (3% body weight) was withdrawn from anesthetized Sprague-Dawley rats and isovolumically replaced with shed blood (SB, control), lysed shed blood (LB, pos. control), human stroma-free hemoglobin solution (SFH), or polyhemoglobin solution (PHS). Thirty minutes after the exchange transfusion, colloidal carbon was injected intravenously and its vascular clearance followed for 1 hour. Then, the 50% exchange transfusion was repeated and the second carbon clearance measured. The intravascular carbon clearance constants, K, and clearance half-times, T1/2, were calculated and compared. No apparent differences in RE function were seen among the groups after the initial exchange transfusion. However, following the second exchange transfusion significant (P less than 0.05) slowing of carbon clearance was observed in lysed blood treated animals. The RE function of SFH or PHS treated animals were not different (P less than 0.05) from that of SB animals. A double exchange transfusion-double carbon clearance method seems to reveal changes in RE function that are not apparent after a single exchange transfusion and clearance test.