Hydroxyethyl Starch, a Synthetic Colloid Used to Restore Blood Volume, Attenuates Shear-Induced Distortion but Accelerates the Convection of Sodium Hyaluronic Acid

Hyaluronic acid (HA) plays important roles in tissue hydration and the transport of fluid and solutes through the interstitium. Hydroxyethyl starch (HES) solution is a synthetic colloid solution used during surgery. As HES leaks into the interstitium under inflammatory conditions during surgery, the effects of HES on HA’s structure and distribution are of clinical relevance. To examine these under fluid shear stress, dynamic shear moduli of 0.1% sodium hyaluronic acid (NaHA) solution with or without HES during shear stress loading were measured using a rotational rheometer for 8 h. The loss shear modulus of NaHA in 0.15 M NaCl solution decreased over time by 30% relative to that before shear stress loading. The presence of 1% and 2% HES reduced the decrease in loss shear modulus of NaHA solution to 20% and 4%, respectively. To investigate the convective transport of 0.1% fluorescein-labeled hyaluronic acid (FHA) by infusion of 0.15 M NaCl or HES solution, the absorbance of FHA in a UV flow cell was continuously measured. HES solution of 0.5% increased transported FHA quantities by 120% compared to 0.15 M NaCl solution. HES-induced attenuation of shear-induced distortion of HA and acceleration of convective transport of HA should be considered during surgery.