The effects of hydroxyethyl starches of varying molecular weights on platelet function

We evaluated the effect of various hydroxyethyl starch (HES) solutions on p latelet function. Blood was obtained before and after the IV infusion (10 m L/kg) of saline tit = 10), HES 70/0.5-0.55 (molecular weight in kD/degree o f substitution; n = 10), HES 130/0.38-0.45 (n = 10), HES 200/0.6-0.66 (n = 10), or HES 450/0.7-0.8 (n = 10) in otherwise healthy patients scheduled fo r elective surgery. Collagen and epinephrine were used as agonists for asse ssment of platelet function analyzer closure times. Flow cytometry was used to assess agonist-induced expression of activated glycoprotein IIb/IIIa co mplex and P-selectin. infusion of HES 450/0.7-0.8, HES 200/0.6-0.66, and HE S 70/0.5-0.55 prolonged closure times and reduced glycoprotein IIb/IIIa exp ression, whereas saline and HES 130/0.38-0.45 had no significant effect on platelet variables. P selectin expression was not affected by any solution tested. In vitro experiments demonstrated a less inhibiting Effect of HES 1 30/0.38-0.45 on closure times when compared with other HES solutions. This study shows that HES 450/0.7-0.8, HES 200/0.6-0.66, and HES 70/0.5-0.55 inh ibit platelet function by reducing the availability of the functional recep tor for fibrinogen on the platelet surface. Our data indicate that fluid re suscitation with HES 130/0.38-0.45 may reduce the risk of bleeding associat ed with synthetic colloids of higher molecular weight and degree of substit ution.