Systematic <i>in silico</i> investigation of the blood hyperviscosity syndrome and its biophysical origins

Hyperviscosity syndrome (HVS) is a disease accompanied by an increase in the blood viscosity and is commonly classified with regards to its cause: (a) serum or plasma hyperviscosity due to an increase in immunoglobulins, and (b) whole-blood hyperviscosity associated with abnormalities in properties of red blood cell (RBC) or plasma protein fractions. The main causes of the whole-blood HVS are the aggregation of RBCs due to the increase of proteins especially fibrinogen, overproduction of RBCs called polycythemia, and changing the mechanical properties of RBCs such as loss of deformability. Blood viscosity measurement is an essential need in the process of diagnosis and treatment. The in vitro experimental rheometry techniques are challenging due to the lack of systematic control over all biophysical processes involved while numerical methods are accurate and powerful alternatives. In this work, we implement a Dissipative Particle Dynamic method to study the effects of some important factors like plasma viscosity, RBC volume fraction, aggregation, and RBC deformability on the overall viscosity of blood. Our results indicate that the increase in the fibrinogen concentration, leading to effective attraction to emerge between RBCs plays a major role in increasing blood viscosity.