Systematic evaluation of evidence on veterinary viscoelastic testing Part 4: Definitions and data reporting

Abstract

Objective To systematically examine evidence surrounding definitions and reporting of data for viscoelastic testing in veterinary medicine. Design Standardized, systematic evaluation of the literature, categorization of relevant articles according to level of evidence and quality, and development of consensus on conclusions for application of the concepts to clinical practice. Setting Academic and referral veterinary medical centers. Results Databases searched included Medline, CAB abstracts, and Google Scholar. Conclusions All 4 standard thromboelastography (TEG) and rotational thromboelastometry (ROTEM) variables should be universally reported, and the reporting of shear elastic modulus in addition to maximum amplitude (MA) is encouraged. There is insufficient evidence to support universal usage of the coagulation index at this time. The K value and clot formation time are the most variable of the 4 parameters, with alpha angle, MA, and maximum clot firmness generally the least variable. Individual studies should report sufficient data on patients and institutional controls to enable definitions of hypo‐ and hypercoagulability to be evaluated post‐hoc, and it is recommended that all studies specifically report how these conditions were defined. In reporting data relating to fibrinolysis, the TEG variables LY30, LY60, CL30, CL60, and the ROTEM variables LI30, LI60, ML, LOT, and LT should be documented. Studies should report sufficient data on patients and controls to enable definitions of hyper‐ and hypofibrinolysis to be evaluated post‐hoc, and we suggest that standard TEG/ROTEM assays may be unable to detect hypofibrinolysis in companion animals. We recommend that every center establish reference intervals, which are specific to either TEG or ROTEM. These reference intervals should be established using veterinary clinical pathology guidelines, standardized protocols, and a minimum of 40 healthy animals. There are currently insufficient data in companion animals to suggest a utility for Vcurve variables beyond that of standard TEG variables.

Hemorrhagic, Hemostatic, and Thromboelastometric Disorders in 35 Dogs with a Clinical Diagnosis of Leptospirosis: A Prospective Study

“…In this previous study, the 4 measured parameters and 5 calculated indices (maximal clot elasticity, G, TPI, global index, and coagulation index) were evaluated to establish their sensitivity and specificity for identifying an exTEM hypocoagulable or hypercoagulable profile. An exTEM profile was arbitrarily considered abnormal if ≥2 of the measured parameters changed in the same direction (e.g, a shortened CT or CFT or an increased α‐angle or MCF to identify a hypercoagulable profile; or a prolonged CT or CFT or decreased α‐angle or MCF to identify a hypocoagulable profile) . According to the results of this previous study, G and TPI appeared to be the best indices for identifying hypercoagulable (AUC = 0.998 and AUC = 0.991, respectively) and hypocoagulable profiles (AUC = 0.987 and AUC = 0.999, respectively).…”

“…A model‐based scoring system was developed in veterinary medicine, but the application of this scoring system was not possible in this study, because it used reference intervals for tests performed at 1 specific laboratory. Finally, no discard tube was used to collect the blood samples, unlike the recommended standard . It is possible that this method of blood collection led to preanalytical bias.…”

Characteristics of hemostasis during experimentalEhrlichia canisinfection

“…The results from TF‐TEG and TF + tPA‐TEG showed that experimentally inoculated dogs appeared hypercoagulable as compared with baseline as defined by a higher MA value and hypofibrinolytic as defined by a lower LY30 and LY60 and a higher CL30 and CL60 . Additional analyses were performed to compare week 3 results to those from subsequent time points, because it was unknown if doxycycline administration would affect TEG parameters.…”

“…The velocity curve variables are generated from the TEG tracing and represent the first derivative of the associated waveform. These variables provide information regarding clot formation and clot breakdown . The MRTG reflects the maximal velocity of increase in clot strength and observed clot growth whereas TMRTG reflects the time interval required to reach maximal rate of clot formation .…”

Veterinary Pathology – A Path Forward with New Directions and Opportunities

“…Nevertheless, many laboratories voluntarily participate in external proficiency testing, with recommendations for this testing being established by the American Society of Veterinary Clinical Pathology (23). Guidelines and consensus statements have been generated for several diagnostic activities, including reference interval establishment (24), prognostic markers in cancer (25), flow cytometric reporting in canine hematopoietic neoplasia (26), immunocytochemical staining (27), and viscoelastic-based hemostasis testing (28), to name a few examples. Similarly, cytologic (29) and histologic (30, 31) grading schemes have been proposed for various tumors.…”