Summary The aim of this study was to investigate the effects of various gelatin and hydroxyethyl starch solutions on platelet reactivity. Citrated whole blood was obtained from 20 healthy volunteers. Expression of glycoprotein (GP) IIb–IIIa and p‐selectin were determined using whole blood flow cytometry on both resting and agonist‐activated platelets before and after in vitro haemodilution (20% and 40%) using oxypolygelatin, modified gelatin, urea‐linked gelatin, hydroxyethyl starch (HES) 130 (mean molecular weight in kDa), HES 200, HES 450 and HES 550. High degrees of haemodilution using oxypolygelatin had no significant effect, similar to HES 130, whereas modified gelatin inhibited GP IIb–IIIa expression, similar to HES 200 and HES 450. Urea‐linked gelatin significantly increased the expression of GP IIb–IIIa, similar to HES 550. p‐Selectin expression remained unchanged in all samples. The present in vitro study indicates that chemical characteristics of colloidal solutions modulate their influence on platelet reactivity.

Physicochemical characteristics of hydroxyethyl starch (HES) molecules determine their side effects on hemostasis. Our aim in the present experiments was to test the antiplatelet effect of novel high molecular weight HES. Citrated whole blood was hemodiluted in vitro (0% and 20%) with either HES 550 (Hextend), HES 600 (6%Hetastarch-Baxter), HES 200 (Elohäst), or the solvent of Hextend in its commercially available solution. The availability of glycoprotein IIb-IIIa was assessed on nonstimulated and on agonist-induced platelets using flow cytometry. Glycoprotein IIb-IIIa availability increased significantly after hemodilution with Hextend and its solvent by 23% and 24%, respectively, but decreased in the presence of 6% Hetastarch-Baxter and Elohäst by 18% and 15%, respectively, with no significant difference between the latter two colloids. This study shows that Hextend does not inhibit platelet function as anticipated by its high molecular weight and degree of substitution. The unexpected platelet stimulating effect of Hextend is unique among the currently available HES preparations and may, at least in part, be induced by its solvent containing calcium chloride dihydrate (2.5 mmol/L). The platelet-inhibiting effect of 6%Hetastarch-Baxter was not significantly different from that of medium molecular weight HES 200.

† Hydroxyethyl starch colloid solutions can impair both platelet function and fibrinogen polymerization, but the contribution of the carrier solution is unclear. † The effects of normal saline or balanced electrolyte carrier solutions on platelet aggregation and viscoelastic coagulation parameters were tested in healthy volunteers. † The carrier solution itself had only small effects on platelet aggregation or clot formation in healthy subjects at the volumes infused.Background. Hydroxyethyl starch (HES) solutions alter blood coagulation, mainly platelet function and fibrinogen polymerization. Haemostasis can also be impaired by dilutionalhyperchloraemic acidosis induced by the HES carrier solution. We hypothesized that a saline-based tetrastarch carrier solution impairs parameters of blood coagulation more than a balanced carrier solution.Methods. The study was designed as a prospective, double-blinded, randomized, cross-over trial in healthy male volunteers. At intervals of at least 10 days, 13 subjects received 20 ml kg 21 of balanced or saline-based tetrastarch over 2 h. Blood was subjected to blood gas analysis, assessment of platelet function [with multiple electrode aggregometry (MEA)], and clot formation (with rotational thrombelastometry).Results. Maximum aggregation in response to adenosine diphosphate (ADP) decreased after saline-based HES infusion, but not after balanced solution-based HES infusion. ADPinduced platelet aggregation was significantly lower after saline-based HES compared with baseline (21%; P,0.025) and compared with balanced solution-based HES (17%; P,0.025). There were no significant changes in platelet aggregation induced by thrombin receptor-activating peptide and in any parameter of rotational thrombelastometry. Chloride concentrations were significantly higher after saline-based HES compared with balanced solution-based HES.Conclusions. The carrier solution for HES up to 20 ml kg 21 had little impact on platelet aggregation or clot formation as assessed by MEA and rotational thrombelastometry, respectively. Further clinical studies are required to verify this finding in patients and to correlate results of whole blood aggregometry and rotational thrombelastometry with perioperative bleeding and transfusion requirements.

Our results extend the report of Takeyama et al. At clinically relevant PCC concentrations, the heparin effect was significant in thromboelastometry. The heparin content of PCCs should be considered in clinical routine.

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