An In Vitro Study Comparing the Effects of Hextend, Hespan, Normal Saline, and Lactated Ringer’s Solution on Thrombelastography and the Activated Partial Thromboplastin Time

Objective: The purpose of this study was to determine if 6% HES 450/0.7 (hydroxyethyl starch 450/0.7) in normal saline (Hespan) and 6% HES 450/0.7 in lactated Ringer’s solution (Hextend) have the same inhibition of the intrinsic coagulation pathway and platelet function. Multiple studies have suggested that 6% Hespan inhibits coagulation and increases chest tube drainage and transfusion requirements in cardiac surgical patients. There have been few studies of the effects of 6% Hextend, a relatively new plasma volume expander, on coagulation and the results thus far have been mixed. Design: A prospective in vitro study. Setting: A large academic medical center. Participants: Blood was collected from 30 healthy volunteers. Interventions: The blood was fractionated and diluted by 30% with Hextend, Hespan, normal saline, and lactated Ringer’s solutions, with a native sample for a control. Measurements and main results: Primary outcome measures were thromboelastography and activated partial thromboplastin time (APTT). For each of the TEG parameters, there was no difference between samples diluted with Hextend compared with Hespan ( p ≥ 0.112 in all cases). APTT did not differ significantly between samples diluted with Hextend compared with Hespan ( p = 0.562). Conclusions: This prospective in vitro study suggests that Hextend and Hespan, hydroxyethyl starch 450/0.7 in different base solutions, exhibit the same effect on platelet function as measured by the TEG.