Inhibition of platelet function by hydroxyethyl starch solutions in chronic pain patients undergoing peridural anesthesia.

The use of hydroxyethyl starch (HES) solutions as a fluid replacement before peridural blockade may compromise blood coagulation, thus increasing the risk of neuraxial bleeding. In this prospective, double-blind, placebo-controlled, crossover study, we compared the influence of HES 130 (molecular weight in kilodalton), HES 200, and lactated Ringer's solution on platelet function and hemodynamics in chronic low back pain patients scheduled for peridural blockades. Patients received 3 test infusions of 10 mL/kg each administered IV for 30 min. Collagen/epinephrine and collagen/adenosine diphosphate were used as agonists for assessment of platelet function analyzer-closure times. Arterial blood pressure, heart rate, platelet counts, and hemoglobin levels were documented. Platelet function analyzer-closure times remained stable after lactated Ringer's solution but were significantly prolonged after HES. The platelet-inhibiting effect of HES 200 was more than that of HES 130. Hemodynamic stability was sufficiently maintained by all test infusions. In contrast to previous observations, a relevant antiplatelet effect of both low and medium molecular weight HES solutions was found in this study in chronic pain patients undergoing peridural anesthesia. Because hemostasiological competence is a prerequisite for safe neuraxial blockade, the decision of HES for intravascular fluid administration before blockade should be critically made.