Comparison of Jugular vs. Saphenous Blood Samples, Intrarater and In-Between Device Reliability of Clinically Used ROTEM S Parameters in Dogs

SIMPLE SUMMARY: Viscoelastic coagulation tests such as rotational Thromboelastometry (ROTEM) have many theoretical advantages compared to traditional coagulation testing. As a point-of-care diagnostic device, ROTEM results are directly part of treatment decisions. Therefore, it is crucial to know its reliability and precision. Most recommendations for ROTEM S analyses originate from Thromboelastography (TEG), another viscoelastic coagulation assay. However, evidence about how preanalytical and analytical factors, such as sample collection technique, sample handling and the analysis itself, influence ROTEM results is scarce. Due to the absence of a gold standard method, we assessed accuracy with the coefficient of variation and intraclass correlation coefficient and examined the influence of blood collection site, as well as intrarater and in-between device variability, on ROTEM S results of clinically healthy dogs. We found significant changes between ROTEM S parameters from different blood collection sites and significant intrarater and in-between device variability. These findings were most prominent in tissue-factor-activated tests. To ensure patient safety, we therefore suggest running duplicate measurements and to interpret results obtained from tissue-factor-activated tests with caution, since some of their coefficients of variation were moderate to high. ABSTRACT: Rotational Thromboelastometry (ROTEM) allows for the global assessment of hemostasis in whole blood samples. Preanalytical and analytical factors may influence test results, and data about the reliability and reproducibility of lyophilized ROTEM tests are scarce. Therefore, the objective of this study was to evaluate the influence of blood collection site on ROTEM S parameters and to assess intrarater and in-between device variability. A total of thirty, healthy, staff-owned dogs were included. Blood collection and ROTEM analysis were performed by trained staff according to a standardized protocol. Extrinsically activated (tissue factor; Ex-TEM S), with the addition of cytochalasin for platelet inhibition (Fib-TEM S), and intrinsically activated (In-TEM) analyses were performed. Analysis of our data showed significant variability for various Ex-TEM S and Fib-TEM S parameters from different collection sites and intrarater and in-between device measurements. We conclude that serial monitoring with ROTEM should be performed on the same device, with blood always taken from the same collection site using a standardized blood sampling technique. While In-TEM S, apart from maximum lysis, showed very stable and reliable results, we suggest interpreting especially clotting and clot formation parameters from Ex-TEM S and Fib-TEM S tests with caution and using duplicate measurements to detect outliers and to prevent initiation of incorrect therapies.