Influence of albumin concentration in priming solution on blood viscosity under hypothermic conditions

Objective: Albumin is used routinely as a plasma volume expander in cardiopulmonary bypass operations. The effect of two different concentrations of albumin in Ringer's lactate on blood viscosity was explored in this study. Methods: Ten healthy volunteers (all male) were included in the study, based on their haematocrit levels (42.6 +/- 0.96). Using a heparinised 50-ml syringe, 40 cm(3) of blood were drawn from the antecubital veins of fasting volunteers. Six ml of blood were haemodiluted with 2 ml of albumin (20%), 2 ml of Ringer's lactate containing albumin (1.3%), and 2 ml of Ringer's lactate, in order to simulate cardiopulmonary bypass conditions. Test tubes with the solutions were placed in a 15 degrees C water bath for 25 minutes. Viscosity was measured in the haemodiluted blood samples using an Ostwald viscometer. Relative viscosities of samples were assessed with SPSS software and the ANOVA test. Results: The mean relative viscosity of Ringer's lactate was 4.19 (+/- 0.49), that of Ringer's lactate with 1.3% albumin was 4.30 (+/- 0.31), and of 20% albumin was 7.32 (+/- 0.71). The relative viscosity of Ringer's lactate and Ringer's lactate with 1.3% albumin were statistically similar, but that of 20% albumin was higher than the Ringer's lactate and Ringer's lactate with 1.3% albumin. Conclusion: Albumin is used as a plasma volume expander in priming solutions for cardiopulmonary bypass operations, but its effect on blood viscosity depends on the concentration of albumin used.