Organ Blood Supply and Tissue Oxygenation after Limited Normovolemic Hemodilution with 3% versus 6% Dextran-60

Background: The use of dextran solutions (DX) for hemodilution (HD) is considered being detrimental due to their effects on plasma viscosity. Methods: 14 splenectomized beagles (12.7+1.3 kg) were anesthetized and randomly assigned to HD to 20 vol% hematocrit (hct) with either 3 or 6% DX-60. The effects of HD upon nutritional organ blood flow (radioisotope-labelled microspheres, O 15 µm), local tissue oxygenation (pO2 multiwire surface electrode), plasma and blood volume (131I-labelled dog albumin distribution), and macrohemodynamics were evaluated with regard to actual changes in hct and plasma viscosity, respectively. Results: Normovolemic HD with either solution resulted in equivalent changes in macrohemodynamics, and plasma and blood volume. Despite the increase in plasma viscosity associated with HD using 6% DX-60 (up to 1.45+0.10 mPa-s), blood flow rose in all organs studied (p Conclusion: In comparison to 6% DX-60, the solution of 3% DX-60 is of equivalent efficacy as volume substitute and in the induction of normovolemic HD. The main advantage of 3% DX-60 solution, however, is the fact that twice as much volume can be administered before the recommended maximal daily dose of 1.5 g/kg DX is reached. Of the rheological factors influencing oxygen delivery, hematocrit thus plays the predominant role, while plasma viscosity is of minor importance.