AHEART June 47/6

Caron, Alexis, Patrick Menu, Béatrice Faivre-Fiorina, Pierre Labrude, Abdu Alayash, and Claude Vigneron. Systemic and renal hemodynamics after moderate hemodilution with HbOCs in anesthetized rabbits. Am J Physiol Heart Circ Physiol 278: H1974–H1983, 2000.—Hbbased O2-carrying solutions (HbOCs) have been developed as red blood cell substitutes for use in patients undergoing hemodilution. Variously modified Hb with diverse solution properties have been shown to produce variable hemodynamic responses. We examined, through pulsed-Doppler velocimetry, the systemic and renal hemodynamic effects of dextran-benzene-tetracarboxylate-conjugated (Hb-Dex-BTC), bis(3,5-dibromosalicyl)fumarate cross-linked (aa-Hb), and oraffinose-polymerized (o-raffinose-Hb) Hb perfused in rabbits after moderate hemodilution (30% hematocrit), and we compared the effects of these Hb solutions with the effects elicited by plasma volume expanders. In addition, vascular hindrance (resistance/blood viscosity at 128.5 s21) was calculated to determine whether a moderate decrease in the viscosity of blood mixed with HbOCs may impair vasoconstriction as a result of autoregulation after infusion of cell-free Hb. No changes were observed in renal hemodynamics after hemodilution with reference or Hb solutions. Increase in blood pressure and vascular resistance was found with Hb-DexBTC and aa-Hb (for 180 min) and, to a lesser extent, with o-raffinose-Hb (for 120 min). Furthermore, Hb-Dex-BTC (high viscosity) and o-raffinose-Hb (medium viscosity) induced comparable increases in vascular hindrance (from 0.091 to 0.159 and from 0.092 to 0.162 cm21, respectively) but far less than that produced by aa-Hb (low viscosity, from 0.092 to 0.200 cm21). These results suggest that maintaining the viscosity of blood by infusing solutions with high viscosity makes it possible to limit vasoconstriction due to autoregulation mechanisms and mainly caused by hemodilution per se.