Effects of plasma viscosity modulation on cardiac function during moderate hemodilution

BACKGROUND: Previous studies have found that increasing plasma viscosity as whole blood viscosity decrease has beneficial effects in microvascular hemodynamics. As the heart couples with systemic vascular network, changes in plasma and blood viscosity during hemodilution determine vascular pressure drop and flow rate, which influence cardiac function. This study aimed to investigate how changes in plasma viscosity affect on cardiac function during acute isovolemic hemodilution. MATERIALS AND METHODS: Plasma viscosity was modulated by hemodilution of 40% of blood volume with three different plasma expanders (PEs). Dextran 2000 kDa (Dx2M, 6.3 cP) and dextran 70 kDa (Dx70, 3.0 cP) were used as high and moderate viscogenic PEs, respectively. Polyethylene glycol conjugated with human serum albumin (PEG-HSA, 2.2 cP) was used as low viscogenic PE. The cardiac function was assessed using a miniaturized pressure-volume conductance catheter. RESULTS: After hemodilution, pressure dropped to 84%, 79%, and 78% of baseline for Dx2M, Dx70 and PEG-HSA, respectively. Cardiac output markedly increased for Dx2M and PEG-HSA. Dx2M significantly produced higher stroke work relative to baseline and compared to Dx70. CONCLUSION: Acute hemodilution with PEG-HSA without increasing plasma viscosity provided beneficial effects on cardiac function compared to Dx70, and similar to those measured with Dx2M. Potentially negative effects of increasing peripheral vascular resistance due to the increase in plasma viscosity were prevented.