Intraoperative Hydroxyethyl Starch and its Effects on Different Fibrinogen Measurements

Abstract

Background: Intravenous fluids with synthetic colloids such as hydroxyethyl starch (HES) are known to interfere with plasma fibrinogen concentration measurements. The aim of this study was to evaluate the effects of an HES solution on fibrinogen measurements in a clinical setting. Methods: The study was performed in patients who received at least 1 L of HES during intracranial tumor resection surgery. Blood samples were drawn before the start of surgery (baseline), after infusion of 1 L of HES, and at later time points. The fibrinogen concentration was measured using 3 different methods: (a) enzyme-linked immunosorbent assay (ELISA), (b) Clauss method with a photometric readout, and (c) Clauss method with an electromechanical readout. In addition, the fibrin-based clot quality was evaluated with the thromboelastometric FIBTEM test. Results: Forty patients were enrolled, and 25 patients were included in the analysis. The fibrinogen concentrations at baseline were 2.2, 2.3, and 2.6 g/L and after 1 L of HES 1.6, 1.7, and 1.9 g/L as measured by ELISA, the photometric test, and the electromechanical test, respectively. The electromechanical Clauss test measured significantly higher concentrations at these time points. The relative decrease, however, was comparable between methods (31%, 29%, and 25%, respectively) but significantly lower than the 44% relative decrease with FIBTEM maximum clot firmness. Conclusion: Despite providing different fibrinogen concentration values at baseline, the relative decrease in fibrinogen concentration after HES infusion was comparable among the 3 tests. In contrast, fibrin-based clot quality was more affected than fibrinogen concentration tests by HES infusion.