Today, rotational thrombelastography as a further development of the classical thrombelastography is increasingly applied to assess haemostasis and to predict complications of coagulation. Due to the improved robustness of the method, RoTEM analyses are now also performed outside specialised coagulation laboratories and applied in emergency settings. Since coagulation testing, particularly when performed with different activators, is very sensitive to artifacts due to variations in the proportion to anticoagulants, temperature and concentration of activators, meticulous quality control is indispensable. For this reason, the German Federal Chamber of Physicians has issued rigorous validity ranges for the classic coagulation tests, such as the prothrombin time (PT/INR) or the activated partial thromboplastin time (aPTT) for variation coefficient acceptance, which are audited 4 times a year by external quality control circles. At present, no comparable quality assurance setup exists for whole blood coagulation testing. Thus, knowledge of the analytical limits, restrictions and caveats of this method is central for critical interpretation of the results and reliable clinical application. This review gives an outline of the practicability and accuracy of the RoTEM methodology and illustrates some pitfalls for the use in detecting and predicting disturbances of haemostasis in a case report.

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The comparability between glucose concentrations measured in various sample systems is still a matter of debate. Decision limits are usually determined in venous plasma and then converted to either blood or to the aqueous compartment (activity). The conversion factors recommended have not yet been generally accepted. In the present study, glucose concentrations were determined in blood and plasma with an Ebio analyser (molarity) and in the aqueous compartment with both an EML 105 and an Omni (molality). All analytical results were referred to the same aqueous standard solution. The Ebio results agreed with reference method values in control materials. Concentrations determined in the various sample systems from patients (molarity) correlated well with the molality values measured either with the EML or the Omni. However, the mean values of the EML were not consistent with those derived theoretically by considering the different water content. With the Omni, only molality values in whole blood appeared plausible, but not in plasma, although the two sample systems should provide identical molality values. The EML results were almost identical in whole blood and plasma. Theoretically, glucose molality would be the ideal diagnostic quantity. However, no diagnostic advantage of molality determined in whole blood with the Omni vs. molarity values could be detected in a group of 40 non-diabetic and 27 diabetic subjects.

The following recommendations are based on the instructions of the “Richtlinie der Bundesärztekammer zur Qualitätssicherung quantitativer laboratoriums-medizinischer Untersuchungen” according to the decision of the executive board of the Bundesärztekammer (RiliBäk) as of August 24th 2001. They have exemplary character for hospitals in which the internal quality control of point-of-care testing is under the responsibility of the central laboratory. The recommendations focus on blood glucose, but are also applicable to other analytes with only slight modifications.

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