A novel approach to measuring circulating blood volume: The use of a hemoglobin-based oxygen carrier in a rabbit model

Hemoglobin-based oxygen carriers (HBOC) may be ideal for monitoring circula ting plasma volume (CV-P) and circulating blood volume (CV-B). We used an H BOC (Hemoglobin glutamer-200 [bovine], Oxyglobin(R); Biopure, Cambridge, MA ) as an indicator for relative CV-B in the rabbit model. Accuracy of the te chnique was determined by comparison with the Evans blue dye (EBD) dilution technique in 19 anesthetized female New Zealand rabbits weighing 2.0 to 10 .6 kg. The measurements were performed at baseline, after hemorrhage (1/3 o f CV-B), normovolemic hemodilution (replacement of 1/3 CV-B by Hextend(R); Abbot Laboratories, North Chicago, IL), and hypervolemic hemodilution (addi tional infusion of Hextend(R) in a volume equal to 1/3 of CV-B). Hemoglobin concentration was measured by using a HemoCue(R) photometer (HemoCue AB, A ngelholm, Sweden). EBD concentration was analyzed by using linear regressio n to estimate Time 0 concentration; Time 0 was defined as EBD injection tim e. The difference between CV-P values deter mined by EBD and HBOC dilution was independent from the magnitude of the CV-P value. The relative bias was 1.29 mL, and the precision (one so) was 2.82 mL. The difference did not re ach statistical significance.