Clinical application of viscoelastic point-of-care tests of coagulation-shifting paradigms

An Amplitude Analysis-Based Magnetoelastic Biosensing Method for Quantifying Blood Coagulation

Blood coagulation tests are crucial in the clinical management of cardiovascular diseases and preoperative diagnostics. However, the widespread adoption of existing detection devices, such as thromboelastography (TEG) instruments, is hindered by their bulky size, prohibitive cost, and lengthy detection times. In contrast, magnetoelastic sensors, known for their low cost and rapid response, have garnered attention for their potential application in various coagulation tests. These sensors function by detecting resonant frequency shifts in response to changes in blood viscosity during coagulation. Nevertheless, the frequency-based detection approach necessitates continuous and precise frequency scanning, imposing stringent demands on equipment design, processing, and analytical techniques. In contrast, amplitude-based detection methods offer superior applicability in many sensing scenarios. This paper presents a comprehensive study on signal acquisition from magnetoelastic sensors. We elucidate the mathematical relationship between the resonant amplitude of the response signal and liquid viscosity, propose a quantitative viscosity measurement method based on the maximum amplitude of the signal, and construct a corresponding sensing device. The proposed method was validated using glycerol solutions, demonstrating a sensitivity of 13.83 V-1/Pa0.5s0.5Kg0.5m-1.5 and a detection limit of 0.0817 Pa0.5s0.5Kg0.5m-1.5. When applied to real-time monitoring of the coagulation process, the resulting coagulation curves and maximum amplitude (MA) parameters exhibited excellent consistency with standard TEG results (R2 values of 0.9552 and 0.9615, respectively). Additionally, other TEG parameters, such as R-time, K-time, and α-angle, were successfully obtained, effectively reflecting viscosity changes during blood coagulation.

Point-of-care ClotPro thromboelastography to determine bleeding risk in two cats with factor XII deficiency

Case series summary

Factor XII (FXII) deficiency is a rare autosomal recessive genetic disorder in cats, leading to singular prolonged activated partial thromboplastin clotting time (aPTT) without increased bleeding risk. This case series describes two cats diagnosed with FXII deficiency using the ClotPro system, a point-of-care viscoelastic coagulation test. Both cats exhibited significantly prolonged aPTT and intrinsic pathway clotting time but maintained normal clot strength, as indicated by thromboelastography (TEG). FXII deficiency was confirmed through quantitative ELISA measurement. Despite prolonged clotting times, the cats did not demonstrate clinical bleeding, suggesting that FXII deficiency does not increase bleeding risk. However, larger controlled studies are necessary to further investigate the utility of TEG in cats with FXII deficiency or other coagulation disorders.

Relevance and novel information

This study addresses the diagnostic challenges associated with FXII deficiency, a condition that can lead to misinterpretation of coagulation results and unnecessary treatments. It highlights the application of the ClotPro system in feline medicine, providing deeper insights into coagulation dynamics and confirming that FXII deficiency does not inherently increase bleeding risk despite prolonged clotting times.

Impact of coagulopathy assessment with thromboelastography and thromboelastometry on transfusion requirements in critically ill cirrhosis with nonvariceal bleeding: A prospective observational study

Background

Viscoelastic tests are now routinely used for coagulopathy correction in patients with cirrhosis. Thromboelastography (TEG®) and rotational thromboelastometry (RoTEM®) are the most widely studied tests in this population. However, they have not been compared with each other in critically ill patients with liver disease presenting with nonvariceal bleed. Hence, we aimed to compare these tests for coagulopathy correction in patients with liver disease presenting with nonvariceal bleeding.

Methods

Sixty adult patients with liver cirrhosis presented to the liver intensive care unit, presenting with a nonvariceal upper gastrointestinal (GI) bleed (diagnosed by doing upper GI endoscopy which revealed bleeding from a nonvariceal source) oral or nasal bleed were enrolled. The patients were allocated to the TEG® group (Group T) or RoTEM® group (Group R) depending on the immediate availability of the viscoelastic test. Coagulopathy correction was done in each group as per established protocols and the results were compared.

Results

There was a significant difference in the fresh frozen plasma (FFP) transfusion between the groups. The TEG® group received more FFP when compared to the RoTEM® group (P = 0.001).

Conclusion

RoTEM®-based coagulopathy correction leads to lesser use of blood products with similar control of bleeding when compared to TEG, in critically ill patients with cirrhosis.

Anticoagulation Management in V-V ECMO Patients: A Multidisciplinary Pragmatic Protocol

(1) Background: Extracorporeal membrane oxygenation (ECMO) is a complex procedure affecting both the risk of thrombosis and bleeding. High-quality data to personalize anticoagulation management in ECMO are lacking, resulting in a high variability in practice among centers. For this reason, we review coagulation methods and monitoring and share a pragmatic proposal of coagulation management, as performed in our high-volume ECMO Referral Centre; (2) Methods: We revised the anticoagulation options and monitoring methods available for coagulation management in ECMO through PubMed search based on words including "anticoagulation," "coagulation assays," "ECMO," "ELSO," and "ISTH"; (3) Results: Actual revision of the literature was described as our routine practice regarding ECMO anticoagulation and monitoring; (4) Conclusions: No coagulation test is exclusively predictive of bleeding or thrombotic risk in patients undergoing ECMO support. An approach that allows for a tailored regimen of anticoagulation (regardless of agent used) and monitoring is mandatory. To accomplish this, we propose that the titration of anticoagulation therapies should include multiple laboratory tests, including anti-Xa, aPTT, ACT, viscoelastic tests, AT levels, platelet count, fibrinogen, and FXIII levels. Anticoagulation regimens should be tailored to a specific patient and personalized based on this complex array of essays.

Mitral valve replacement in patients of rheumatic heart disease associated with immune thrombocytopenia

Immune thrombocytopenia in association with rheumatic heart disease is not commonly seen. Surgical management of rheumatic heart disease becomes more challenging in the presence of immune thrombocytopenia. The risk of complications increases manifold and judicious medical management before, during, and after surgery is imperative. We discuss two such cases, the complications we faced and the problems we anticipated before, and their prevention. Both patients were managed without using immunoglobulins or doing splenectomy. The literature on valve replacement in patients of immune thrombocytopenia and the implications of immune thrombocytopenia in the management of patients with rheumatic heart disease is also reviewed.

Modified Rotational Thromboelastometry Protocol Using Tissue Plasminogen Activator for Detection of Hypofibrinolysis and Hyperfibrinolysis

Viscoelastic testing includes thromboelastography (TEG^®) and thromboelastometry (ROTEM^®) and is widely used in bleeding patients to detect hypocoagulability and guide transfusion therapy. However, the ability of standard viscoelastic tests to assess fibrinolytic capacity is limited. We here describe a modified ROTEM^® protocol with addition of tissue plasminogen activator that can be used to identify hypofibrinolysis or hyperfibrinolysis.

Evaluation of Blood Coagulation by Optical Vortex Tracking

Blood coagulation is a complicated dynamic process that maintains the blood's fluid state and prevents uncontrollable bleeding. The real-time monitoring of coagulation dynamics is critical for blood transfusion guidance, emergency management of trauma-induced coagulopathy, perioperative bleeding, and targeted hemostatic therapy. Here, we utilize optical vortex dynamics to detect the blood coagulation dynamic process in a rapid and non-contact manner. To characterize the temporal changes in viscoelastic properties of blood during coagulation, we track the stochastic motion of optical vortices in the time-varying speckles reflected from 100 blood samples with varied coagulation profiles. The mean square displacement (MSD) of the vortices increases nonlinearly with time lag during blood coagulation reminiscent of the particles in viscoelastic fluids. The MSD curves with coagulation time are similar to the tracings of thromboelastography (TEG) during the blood coagulation. The retrieved coagulation parameters, such as reaction time and activated clotting time measured using the optical vortex method, exhibit a close correlation to those parameters acquired from TEG. These results demonstrate the feasibility of the optical vortex method for monitoring blood coagulation at the point of care. Our method is also applicable to measuring the viscoelasticity of complex fluids and turbid soft matters.