title: The viscous behaviour of HES 130/0.4 (Voluven®) and HES 260/0.45 (Pentaspan®).
abstract: OBJECTIVE
  Several fluids are available for volume therapy to address hypovolemia. We focus on two hydroxyethyl starches (HES) available for volume expansion in Canada, HES 130/0.4 (Voluven®) and HES 260/0.45 (Pentaspan®). Although information is available regarding their pharmacokinetic and risk/benefit profiles, this paper examines their viscous properties.
  
  
  METHODS
  Dynamic viscosities of HES 130/0.4 and HES 260/0.45 were measured through capillary viscometry at 21°C and 37°C. The viscosities of the solutions were then measured through a closed flow loop at room temperature across physiologically relevant flow rates that maintained a laminar flow regime.
  
  
  RESULTS
  Measured dynamic viscosity through capillary viscometry for HES 130/0.4 and HES 260/0.45 was 2.76 centipoises (cP) and 7.62 cP, respectively, at 21°C decreasing to 1.74 cP and 4.25 cP, respectively, at 37°C. Pipe flow analysis found that HES 130/0.4 (expiry 02/13) and HES 260/0.45 (expiry 10/10) displayed marginal variation in viscosity suggesting Newtonian behaviour. However, a sample of HES 130/0.4 (expiry 10/10) displayed an appreciable increase in viscosity (13%) at higher flow rates suggesting shear thickening behaviour.
  
  
  CONCLUSIONS
  This study represents an innovative characterization of not only the viscosity of two commonly utilized HES solutions but also their viscous behaviour across physiologically relevant flow rates. The shear thickening behaviour of a sample of HES 130/0.40 (expiry 10/10) at high flow rates was not expected, and the effect this result may have on endothelial cell function is unknown.
authors.affiliation: Department of Mechanical and Manufacturing Engineering, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada. walkeram@ucalgary.ca
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Walker
authors.forename: Kogan
authors.initials: K
authors.lastname: Lee
authors.forename: Gary M
authors.initials: GM
authors.lastname: Dobson
authors.forename: Clifton R
authors.initials: CR
authors.lastname: Johnston
mesh_terms: D006895:Hydroxyethyl Starch Derivatives / Q000737:chemistry*; D010952:Plasma Substitutes / Q000737:chemistry*; D033081:Shear Strength; D014783:Viscosity
chemical_list: C485123:HES 130-0.4; D006895:Hydroxyethyl Starch Derivatives; D010952:Plasma Substitutes