Coagulation Monitoring: Current Techniques and Clinical Use of Viscoelastic Point-of-Care Coagulation Devices

Abstract

Perioperative monitoring of blood coagulation is critical to better understand causes of hemorrhage, to guide hemostatic therapies, and to predict the risk of bleeding during the consecutive anesthetic or surgical procedures. Point-of-care (POC) coagulation monitoring devices assessing the viscoelastic properties of whole blood, i.e., thrombelastography, rotation thrombelastometry, and Sonoclot analysis, may overcome several limitations of routine coagulation tests in the perioperative setting. The advantage of these techniques is that they have the potential to measure the clotting process, starting with fibrin formation and continue through to clot retraction and fibrinolysis at the bedside, with minimal delays. Furthermore, the coagulation status of patients is assessed in whole blood, allowing the plasmatic coagulation system to interact with platelets and red cells, and thereby providing useful additional information on platelet function. Viscoelastic POC coagulation devices are increasingly being used in clinical practice, especially in the management of patients undergoing cardiac and liver surgery. Furthermore, they provide useful information in a large variety of clinical scenarios, e.g., massive hemorrhage, assessment of hypo- and hypercoagulable states, guiding pro- and anticoagulant therapies, and in diagnosing of a surgical bleeding. A surgical etiology of bleeding has to be considered when viscoelastic test results are normal. In summary, viscoelastic POC coagulation devices may help identify the cause of bleeding and guide pro- and anticoagulant therapies. To ensure optimal accuracy and performance, standardized procedures for blood sampling and handling, strict quality controls and trained personnel are required.

Perioperative coagulopathy monitoring

“…Furthermore, ROTEM not only provides a global picture of the injured patient's hemostatic status, but also permits differential diagnosis of the major underlying pathomechanism of coagulopathy by implementing test modifications. The addition of various coagulation-activating agents and/or platelet-inhibiting agents allows for the detection and quantification of specific coagulation defects, such as defect in clot firmness due to fibrinogen deficiency and thrombocytopenia, prolonged clot generation due to various coagulation factor deficiencies or heparin, and impaired clot stability due to hyperfibrinolysis and factor XIII deficiency [6]. Interpretation of TEG/ROTEM results is simplified by both graphical and numerical presentation of results, quickly highlighting abnormalities.…”

“…Interpretation of TEG/ROTEM results is simplified by both graphical and numerical presentation of results, quickly highlighting abnormalities. TEG/ROTEM measurements can be taken at the patient's actual body core temperature between 22 and 42°C, thus allowing quantitative analysis of the anticoagulant effect of temperature physiology [6,8]. Transfusion requirements before and after the implementation of ROTEM were statistically significantly lower and clinically more accurate [7].…”

“…Critical MCF cut-off values appear within 15 min after test initiation. A low MCF FIB-TEM suggests the administration of fibrinogen concentrates, while a normal MCF FIBTEM (C12 mm) in the presence of a low MCF ExTEM (\50 mm) suggests the need for platelet substitution [6]. Thus, comparing MCF FIBTEM with MCF ExTEM permits the differentiation of coagulopathy secondary to either a low platelet count or dys-or hypofibrinogenemia.…”

“…In the United States, coagulation test results are also obtained after a significant delay and may not reflect the current state of hemostatic physiology, potentially leading to delayed or inappropriate treatment [5][6][7][8][9][10][11][12][13][14][15][16][17]. The use of bedside tests, called point-of-care (POC) tests, may partly compensate for the methodological limitations and diagnostic shortfalls of conventional coagulation testing [6][7][8][9][10][11][12][13][14][15][16][17].…”

“…The use of bedside tests, called point-of-care (POC) tests, may partly compensate for the methodological limitations and diagnostic shortfalls of conventional coagulation testing [6][7][8][9][10][11][12][13][14][15][16][17]. While none of the currently available methods of POC coagulation testing can provide an adequate picture of the entire coagulation spectrum alone, multiple methods used together may allow for a comprehensive diagnostic evaluation.…”