Thromboelastography and thromboelastometry and the management of intra-operative transfusion therapy in massively bleeding patients.

Abstract

Dear Sir, I have read with interest the letter “Intra-operative transfusion management: the usefulness of point-of-care coagulation monitoring” by Feltracco et al1. Severe bleeding and coagulopathy as a result of massive transfusion are serious clinical conditions that are associated with high mortality. Since the first description in 1948, thromboelastography (TEG) and thromboelastometry (ROTEM) have been successfully used as a point-of-care tests as they are capable of providing a robust and cheap snapshot of haemostasis at the bedside. The study of visco-elastic properties of clots carried out through TEG and ROTEM is being increasingly used to guide transfusion strategies in patients with massively bleeding. TEG and ROTEM are easy to use by non-laboratory personnel as point-of-care tests in peri-operative and emergency settings. They produce rapid graphical and numerical results of the haemostatic status and are able to detect the anticoagulant effect of acidosis, hypothermia or hyperthermia, as they can be performed at temperatures between 22 °C and 42 °C. Finally, they are able to detect and quantify the underlying cause of coagulopathy, such as thrombocytopenia, clotting factor deficiency, heparin effect, hypofibrinogenaemia, and hyperfibrinolysis2. The test is carried out on a sample of whole blood and helps the clinicians to assess the cause of bleeding so that they can initiate the relevant transfusion or pharmacological therapy for coagulation problems resulting from clinical conditions such as trauma, surgery or potential disseminated intravascular coagulation. Notwithstanding their increased use to guide transfusion therapy the role of TEG and ROTEM remain controversial, and the role of the Sonoclot analyser currently seems even more limited, at least for managing transfusion therapy. A recently published Cochrane review had the objective of systematically assessing the benefits and harm of a TEG- or ROTEM-guided transfusion strategy in randomised trials involving patients with severe bleeding3. There is a lack of evidence that a TEG- or ROTEM-guided strategy improves, compared with standard treatment, morbidity or mortality in patients with severe bleeding. A statistically significant effect on the amount of bleeding was detected but the “analyses on the proportion of patients transfused with red blood cells, fresh-frozen plasma (FFP) and platelets did not show a statistically significant reduction”. However, the “analyses on the proportion of patients receiving both FFP and platelets did show a statistically beneficial reduction (RR 0.39, 95% CI 0.27 to 0.57, I2=0) when applying TEG or ROTEM. The true value of these analyses is unclear due to limited amounts of data and lack of a significant reduction in the amount of transfused FFP or platelets when examined separately”. These results call for further studies that are well designed and correctly powered to increase the level of evidence on the efficacy of these point-of-care devices in increasing the appropriate use of blood products. Furthermore, these devices can be really advantageous only when appropriately trained personnel are available, also in peri-operative and emergency settings. In fact, adequate and continuous training of non-laboratory personnel in charge of carrying out the tests and a thorough knowledge of good laboratory practice are really the essential requirements for producing reliable results, regardless of where the test is performed. In addition, an accredited external quality assessment programme and internal quality control system must be established4. For the above reasons the recently issued SIMTI guidelines did not include any recommendations on the routine use of TEG or ROTEM5. Despite the non-inclusion of TEG/ROTEM in the SIMTI guidelines, there is a more than reasonable expectation that, in the near future, the study of visco-elastic properties of clot will provide a higher level of evidence showing that TEG/TOGEM is a suitable method for guiding appropriate transfusion management of patients with massive bleeding. However, these point-of-care tests will express all their potential and be really cost-effective and efficacious in providing reliable results to guide transfusion strategy only in skilled hands and provided that validation of the technique, periodic competency assessments and good laboratory practice are ensured4, also outside the laboratory setting.