Effects of replacement fluids on plasma viscosity used for therapeutic plasma exchange

Plasmapheresis is a widely used alternative treatment for several diseases. Recently, synthetic plasma expanders have been used to reduce the cost of therapeutic plasma exchange (TPE). Hydroxyethyl starch (HES) is a polysaccharide colloid. Isohes and Varihes are plasma volume expanders containing 6% HES in 0.9% NaCl solution. In this study, we aimed to compare the effects of several replacement fluids used for TPE on plasma viscosity profile. At the same time, we evaluated the correlation between plasma viscosity and fibrinogen level. Twenty-nine patients were enrolled for this study. Patients were divided into four groups based on replacement fluids used: 3% HES + 4% albumin (group 1), FFP (group 2), 3% Varihes (450000/ 0.7)/Isohes(200000/0.5) (group 3), and 4% albumin (group 4). The choice of replacement fluids used was randomly assigned, as long as there were no contraindications for the patient. Seven samples were collected to determine plasma viscosity and fibrinogen level during TPE cycles. There was a positive exponential correlation between plasma viscosity and fibrinogen levels. At the second plasmapheresis procedure, plasma viscosity and fibrinogen levels decreased by 20% compared with first cycle. The effect of plasmapheresis solutions on hemorheology were roughly the same. Effects of replacement fluids on plasma viscosity were comparable.