title: Influence of red blood cell aggregation on perfusion of an artificial microvascular network.
abstract: RBCs suspended in plasma form multicellular aggregates under low-flow conditions, increasing apparent blood viscosity at low shear rates. It has previously been unclear, however, if RBC aggregation affects microvascular perfusion. Here, we analyzed the impact of RBC aggregation on perfusion and 'capillary' hematocrit in an AMVN at driving pressures ranging from 5 to 60 cm H2O to determine if aggregation could improve tissue oxygenation.
  
  
  
  RBCs were suspended at 30% hematocrit in either 46.5 g/L dextran 40 (D40, non-aggregating medium) or 35 g/L dextran 70 (D70, aggregating medium) solutions with equal viscosity.
  
  
  
  Aggregation was readily observed in the AMVN for RBCs suspended in D70 at driving pressures ≤40 cm H2O. The AMVN perfusion rate was the same for RBCs suspended in aggregating and non-aggregating medium, at both 'venular' and 'capillary' level. Estimated 'capillary' hematocrit was higher for D70 suspensions than for D40 suspensions at intermediate driving pressures (5-40 cm H2O).
  
  
  
  We conclude that although RBC aggregation did not affect the AMVN perfusion rate independently of the driving pressure, a higher hematocrit in the 'capillaries' of the network for D70 suspensions suggested a better oxygen transport capacity in the presence of RBC aggregation.
authors.affiliation: Department of Internal Medicine, Kantonsspital Graubünden, Chur, Switzerland.
authors.forename: Walter H
authors.initials: WH
authors.lastname: Reinhart
authors.affiliation: Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, Texas, USA.
authors.forename: Nathaniel Z
authors.initials: NZ
authors.lastname: Piety
authors.affiliation: Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, Texas, USA.
authors.forename: Sergey S
authors.initials: SS
authors.lastname: Shevkoplyas
mesh_terms: D001809:Blood Viscosity; D004903:Erythrocyte Aggregation; D006400:Hematocrit; D006801:Humans; D055806:Microvessels / Q000502:physiology*; D008955:Models, Cardiovascular; D010100:Oxygen / Q000378:metabolism; D010477:Perfusion
chemical_list: D010100:Oxygen
keywords: artificial microvascular network; dextran; hematocrit; microvascular perfusion; red blood cell aggregation