The impact of a medium molecular weight, low molar substitution hydroxyethyl starch dissolved in a physiologically balanced electrolyte solution on blood coagulation and platelet function in vitro

Hydroxyethyl starches (HES) may have the potential to impact negatively on haemostasis. Recent findings suggest that side-effects on haemostasis stem not only from the physicochemical differences between HES, but also from the composition of the solvent. We compared the effects of a newly developed medium molecular weight (MW) and low molar substitution (MS) HES dissolved in a physiologically balanced electrolyte solution (MW 130, MS 0.42; B-HES) with a commercially available non-balanced HES (MW 130, MS 0.4; NB-HES), and with Ringer's lactate (RL) solution in vitro. Activated partial thromboplastin time (APTT), factor VIII clotting activity (F VIII:C) and von Willebrand factor (vWF) activity were investigated in 48 healthy individuals. Platelet function as measured by turbidimetric platelet aggregometry and whole blood impedance aggregometry induced by adenosine diphosphate (ADP), collagen and thrombin receptor activating peptide (TRAP), and by ADP and TRAP-induced expression of activated platelet fibrinogen receptor glycoprotein (GP) IIb/IIIa was determined in 24 participants. Haemodilution (25% and 50%, v/v for blood coagulation analyses and 20% and 40%, v/v for platelet function studies) was performed using the two HES preparations and RL. APTT was significantly longer and F VIII and vWF significantly lower at 25% and 50% dilutions with NB-HES compared to B-HES and RL. At 20% and 40% dilutions, ADP and TRAP-induced expression of activated platelet surface GP IIb/IIIa was significantly increased by B-HES compared to NB-HES and RL. Percentages of platelet GP IIb/IIIa expression were also significantly greater in samples diluted with B-HES than in undiluted blood. Neither the diluent (B-HES, NB-HES and RL) nor the degree of dilution (undiluted, 20% and 40% dilution) had any significant influence on ADP, collagen or TRAP-induced turbidimetric platelet aggregation or impedance platelet aggregation. In contrast to a non-balanced 130 kDa, MS 0.4 HES (NB-HES), a 130 kDa, MS 0.42 HES preparation dissolved in a physiologically balanced electrolyte solution (B-HES) does not affect APTT, F VIII:C and vWF in vitro. Both types of HES do not affect platelet aggregation induced by ADP, collagen or TRAP. B-HES but not NB-HES increases the expression of activated platelet GP IIb/IIIa induced by ADP or TRAP.