Dextran and hydroxyethyl starch do not interfere with fibrinogen measurement if Clauss method with mechanical clot detection is used

Abstract

In an updated European guideline for the management of bleeding following major trauma, published in a recent issue of Critical Care, Rossaint and colleagues [1] recommended that thrombelastometry instead of other laboratory methods be used to measure fi brinogen. Th e authors stated that the Clauss method [2] overestimates fi brino gen concentration when colloids are given. Th is claim is supported by studies of patients receiving colloids in which fi brinogen was measured by an automated Clauss assay performed on an ACL-300R coagulometer (Instrumentation Laboratory, Bedford, MA, USA), which detects clot formation photo-optically [3]. Automated coagulometers use diff erent technologies to detect fi brin clot endpoints. Some coagulometers employ mechanical principles involving the movement of a metal hook or the clot impedance of a ball bearing in a magnetic fi eld; others use photo-optical devices to measure changes in light transmission [2]. Recently, Adam and colleagues [4] analyzed plasma diluted with diff erent proportions of saline or hydroxyethyl starch (HES). Fibrinogen concentration was overestimated if the clotting time was measured photooptically in samples diluted with HES. But fi brinogen measurements in analyzers that used mechanical clot detection endpoints were accurate. Fenger-Eriksen and colleagues [5] assessed the accuracy of fi brinogen measure ments in diff erent analyzers and diff erent methods in plasma diluted in diff erent proportions with saline, HES, and albumin. Th e authors found that the photo-optical measurement overestimated fi brinogen concentration but that mechanical detection did not. Th romboelastometry seems to be a rapid and accurate estimation of the level and function of fi brinogen but is not available in most centers. However, most laboratories can easily measure fi brinogen by the Clauss method using mechanical detection. We recommend that the European guidelines specifying the use of thromboelastometry over the Clauss method be revised and qualifi ed accordingly.