Viscoelastic Coagulation Testing Research Articles

Evolution of the Use of Therapeutic Fibrinogen Concentrate in the Massive Bleeding Guidelines

Fibrinogen concentrate was approved for the first time in the European Union by the German Federal Ministry of Health on January 4th, 1966. Since then, its use has been shown to be effective and well-tolerated in numerous clinical studies with congenital or acquired fibrinogen deficiency. In this review, we analyze the evolution of the indications for the use of fibrinogen concentrate in massive bleeding guidelines in three main clinical scenarios of acquired hypofibrinogenemia, such as cardiac, obstetric, and polytrauma patients. In cardiac surgery, the administration of fibrinogen has become a noteworthy tool in the management of perioperative haemostasis. The implementation of therapeutic algorithms, together with the use of viscoelastic coagulation tests, has allowed a faster and more personalized diagnosis and treatment of perioperative bleeding. In obstetrics, fibrinogen administration has evolved significantly over the years to a part of the management of massive obstetric haemorrhage, with early administration of fibrinogen now considered important in cases of hypofibrinogenemia during haemorrhage, helping to effectively correct coagulopathy and improve maternal outcomes. Currently, the implementation of protocols based on point-of-care viscoelastic testing has proven to be useful in the management of obstetric haemorrhage. In polytrauma patients with severe bleeding, fibrinogen administration is recommended based on clinical criteria and prior to laboratory test outcomes. After this first approach, guidelines recommend goal-directed coagulation management based on the results of viscoelastic tests and, in their absence, classical laboratory tests are recommended.

Paying attention to the value of thrombelastography and the impact of postreperfusion syndrome on outcomes of liver transplantation.

Only limited information is available about the connection between massive blood transfusion and postoperative survival rates in pediatric liver transplantation. The aim of Gordon's study was to examine the potential impact of perioperative transfusion on postoperative complications and death in young children receiving pediatric living-donor liver transplantation (PLDLT). The authors concluded that transfusion of a red blood cell volume higher than 27.5 mL/kg during the perioperative period is associated with a significant increase in short- and long-term postoperative morbidity and mortality after PLDLT. However, viscoelastic coagulation monitoring was not utilized in the study; instead, only conventional coagulation monitoring was conducted. Overall, the choice of blood coagulation monitoring method during blood transfusion can have a significant impact on patient prognosis. Several studies have shown that the viscoelastic coagulation testing such as thrombelastography (TEG) is highly sensitive and accurate for diagnosing coagulation dysfunction. Indeed, a TEG-guided blood transfusion strategy can improve prognosis. Moreover, postreperfusion syndrome is one of the most common complications of liver transplantation and an important factor affecting the prognosis of patients and should also be included in regression analysis.

Evaluation of hemostatic derangements associated with canine anaphylaxis and the relationship to syndrome severity.

To describe hemostatic derangements associated with canine anaphylaxis and to assess for association with syndrome severity. Prospective observational study. University teaching hospital. Twenty-seven client-owned dogs, recruited from November 2018 to January 2022, diagnosed with anaphylaxis of varying severity were included. Study inclusion required presentation <6hours after initiation of clinical signs, no medications or history of illness within the prior 2weeks, lack of comorbidities expected to affect hemostasis, and lack of a disease state that could alternatively explain the clinical presentation. Blood samples were collected within the first hour of presentation for CBC, serum biochemistry, prothrombin time (PT), activated partial thromboplastin time (aPTT), and viscoelastic coagulation testing for use with a cartridge-based point-of-care device. Clotting time and clot formation time were prolonged, alpha angle and maximum clot firmness were decreased, PT and aPTT were prolonged, and platelet counts were lower in severe cases compared to mild and moderate cases. There were no differences for any parameter between mild and moderate cases. The presence or absence of abdominal effusion was not associated with hemostatic status. Global hemostatic derangements consistent with hypocoagulability are a prominent feature of severe anaphylaxis in dogs and should be considered for routine evaluation.

THU-369 - Effect of fibrinogen substitution in hypofibrinogenaemic CTP class C patients on viscoelastic coagulation tests

THU-369 - Effect of fibrinogen substitution in hypofibrinogenaemic CTP class C patients on viscoelastic coagulation tests

Thromboelastography in the Perioperative Period: A Literature Review.

Assessing coagulation status is essential for prompt intervention to reduce morbidity and mortality related to bleeding and thrombotic complications during the perioperative period. Traditional coagulation tests such as platelet count,activated partial thromboplastin time (aPTT), prothrombin time (PT), international normalized ratio (INR), and activated clotting time (ACT) provide only static evaluation. These tests are not designed for assessment of dynamically changing coagulation conditions during the perioperative time. However, viscoelastic coagulation testing such as thromboelastography (TEG) produces a rapid numerical and graphical representation that helps to detect and direct targeted hemostatic therapy. Searching the literature through PubMed, Medline, Ovid, CINAHL, and ClinicalTrials.gov we retrieved 210 studies, which represent the use of TEG in the perioperative period. The included studies were categorized under various settings such as trauma, obstetrics, orthopedics, intensive care unit (ICU), cardiovascular, transplant, and miscellaneous scenarios. TEG showed promising results in trauma surgeries in predicting mortality, hypercoagulability, and bleeding even when it was compared to conventional methods. TEG was also useful in monitoring anticoagulant therapy in orthopedic and obstetric surgeries; however, its role in predicting thrombotic events, hypercoagulability, or complications was questionable. In ICU patients, it showed promising results, especially in the prediction or improvement of sepsis, coagulopathy, thrombotic events, ICU duration, hospital stay, and ventilator duration. TEG parameters effectively predicted hypercoagulation in transplant surgeries. Regarding cardiovascular surgeries, they were effective in the prediction of the need for blood products, coagulopathy, thrombotic events, and monitoring anticoagulation therapy. More randomized clinical trials comparing TEG parameters with standardized tools are needed to produce robust results to standardize its use in different perioperative settings.

Factor VIII: A Dynamic Modulator of Hemostasis and Thrombosis in Trauma.

A trace amount of thrombin cleaves factor VIII (FVIII) into an active form (FVIIIa), which catalyzes FIXa-mediated activation of FX on the activated platelet surface. FVIII rapidly binds to von Willebrand factor (VWF) after secretion and becomes highly concentrated via VWF-platelet interaction at a site of endothelial inflammation or injury. Circulating levels of FVIII and VWF are influenced by age, blood type (nontype O > type O), and metabolic syndromes. In the latter, hypercoagulability is associated with chronic inflammation (known as thrombo-inflammation). In acute stress including trauma, releasable pools of FVIII/VWF are secreted from the Weibel-Palade bodies in the endothelium and then augment local platelet accumulation, thrombin generation, and leukocyte recruitment. Early systemic increases of FVIII/VWF (>200% of normal) levels in trauma result in a lower sensitivity of contact-activated clotting time (activated partial thromboplastin time [aPTT] or viscoelastic coagulation test [VCT]). However, in severely injured patients, multiple serine proteases (FXa plasmin and activated protein C [APC]) are locally activated and may be systemically released. Severity of traumatic injury correlates with prolonged aPTT and elevated activation markers of FXa, plasmin, and APC, culminating in a poor prognosis. In a subset of acute trauma patients, cryoprecipitate that contains fibrinogen, FVIII/VWF, and FXIII is theoretically advantageous over purified fibrinogen concentrate to promote stable clot formation, but comparative efficacy data are lacking. In chronic inflammation or subacute phase of trauma, elevated FVIII/VWF contributes to the pathogenesis of venous thrombosis by enhancing not only thrombin generation but also augmenting inflammatory functions. Future developments in coagulation monitoring specific to trauma patients, and targeted to enhancement or inhibition of FVIII/VWF, are likely to help clinicians gain better control of hemostasis and thromboprophylaxis. The main goal of this narrative is to review the physiological functions and regulations of FVIII and implications of FVIII in coagulation monitoring and thromboembolic complications in major trauma patients.

Viscoelastic coagulation testing in Neonatal Intensive Care Units: advantages and pitfalls in clinical practice.

The expression "developmental hemostasis" indicates the age-related physiological changes occurring during the maturational process of the hemostatic system. Despite the quantitative and qualitative alterations, the neonatal hemostatic system is competent and well-balanced. Conventional coagulation tests do not provide reliable information as they only explore the procoagulants during the neonatal period. In contrast, viscoelastic coagulation tests (VCTs), such as viscoelastic coagulation monitoring (VCM), thromboelastography (TEG or ClotPro), and rotational thromboelastometry (ROTEM), are point-of-care assays that provide a quick, dynamic and global view of the hemostatic process, allowing prompt and individualized therapeutic intervention when necessary. Their use in neonatal care is on the increase and they could help monitor patients at risk of hemostatic derangement. In addition, they are crucial for anticoagulation monitoring during extracorporeal membrane oxygenation. Moreover, implementing VCT-based monitoring could optimize blood product use.

“TEG” talks: technology worth spreading?

“TEG” talks: technology worth spreading?

A comparison of the ClotPro system with rotational thromboelastometry in cardiac surgery: a prospective observational study

Viscoelastic coagulation tests have been increasingly used for hemostasis management in cardiac surgery. The ClotPro system is a novel viscoelastic device based on principles of rotational thromboelastometry. We aimed to compare ClotPro with ROTEM and plasma coagulation assays in cardiopulmonary bypass (CPB) patients. Blood samples were collected from 25 CPB patients at (1) baseline, (2) start of CPB, (3) end of CPB, and (4) end of surgery. The EX-test, IN-test, HI-test, FIB-test parameters on ClotPro were compared with corresponding ROTEM assay (EXTEM, INTEM, HEPTEM, and FIBTEM). Standard plasma coagulation assays and endogenous thrombin generation (TG) were simultaneously evaluated. Pearson correlation analyses showed moderate correlations between clotting times (CTs) (r = 0.63–0.67; p < 0.001, respectively), and strong correlations with maximal clot firmness (MCF) (r = 0.93–0.98; p < 0.001, respectively) between ClotPro and ROTEM. EX-test and IN-test MCF parameters were interchangeable with acceptable percentage errors (EX-test MCF: 7.3%, IN-test MCF: 8.3%), but FIB-test MCF (27.0%) and CT results were not (EX-test CT: 44.7%, IN-test CT: 31.4%). The correlations of PT/INR or peak TG with EX-test CTs were higher than with EXTEM CTs (PT/INR: r = 0.80 and 0.41, peak TG: 0.43 and 0.18, respectively). FIB-test MCF has strong correlation with plasma fibrinogen and factor XIII level (r = 0.84 and 0.66, respectively). ROC analyses showed that ClotPro was capable of emulating well-established ROTEM thresholds (area under curves: 0.83–1.00). ClotPro demonstrated strong correlations in MCF parameters of ROTEM in CPB patients. It may be reasonable to modify ROTEM-based transfusion algorithm pertaining to MCF parameters to establish cut-off values for ClotPro device.

The Supply Side of Coagulation: Fibrinogen and Bleeding in Liver Disease and Transplantation.

In this issue of Transplantation, Carrier et al1 describe a study that assesses the effect of preoperative fibrinogen levels on perioperative bleeding and outcomes. In 613 patients with end-stage liver disease who underwent liver transplantation between 2008 and 2019, preoperative low fibrinogen levels were associated with more blood loss but not worse 1-y survival in univariate and multivariate statistical models. This effect was most prominent when fibrinogen levels were below 3 g/L before surgery. In any model of coagulation, fibrinogen is the substrate required to create an effective clot and provide hemostasis. Like most components of hemostasis, fibrinogen is synthesized by the liver and reduced in severe liver disease. Additionally, and maybe more commonly‚ dysfibrinogenemia occurs in liver disease resulting in defects of the fibrinogen structure with undetermined effects on hemostasis.2 The coagulation abnormalities associated with liver disease result in dysbalanced hemostasis that can cause impaired clot formation or excessive thrombosis. Conventional coagulation tests cannot detect this dysbalanced hemostasis‚ as they measure only (a part of) the procoagulant side of hemostasis. Viscoelastic testing, now routinely used in many transplant centers‚ may provide a better assessment of all aspects of clot formation by creating a visual representation of changes in the viscosity of blood when a clot forms. Viscoelastic testing can guide transfusion management in many clinical scenarios‚ including liver transplantation‚ but possibly, more importantly, allows us to identify patients who are hypercoagulable even when the conventional coagulation tests are abnormally high. The results of Carrier et al suggest that low preoperative fibrinogen levels may be an indicator that a patient is at risk for increased intraoperative bleeding. This may be particularly useful if perioperative viscoelastic testing is not used or available as with the study center. This risk of bleeding increased when fibrinogen levels were below 3 g/L before surgery, a level that is far higher than what has traditionally been considered a concerning threshold. Most experts and societies, for example, the review on perioperative coagulation management in liver transplant recipients by Bezinover et al here in Transplantation in 2018,3 recommend fibrinogen concentrate and/or cryoprecipitate transfusion for fibrinogen levels below 1.5 to 2 g/L. Although raising new questions, the present study does not provide enough evidence to change this recommendation at this time. An association with bleeding (even in a multivariate model) does not necessarily mean that replacing fibrinogen with levels over 3 g/L will reduce the risk of bleeding. The assumption is that fibrinogen levels that are below 3 g/L before surgery may decrease more during transplantation to a level that actually impairs hemostasis. Excessive transfusion of cryoprecipitate (and, to a lesser degree, fibrinogen concentrates) is not without risk and may increase the risk of thromboembolic complications.4 The results by Carrier et al are raising new questions about fibrinogen thresholds and may provide the impetus for future (prospective) studies but should not necessarily change our current management. The Centre Hospitalier de L’Universite de Montreal (CHUM) has demonstrated for many years with great success what can be achieved with a concerted effort to reduce blood transfusion5: More than 70% of the patients in the present study did not receive any red blood cell transfusion at all! The center undertakes a number of interventions to achieve these remarkable results. For example, over 50% of the patients in this study underwent phlebotomy at the beginning of surgery. I am not aware of any other center that implemented such a vigorous and successful program to reduce blood transplantation. Unfortunately, this also limits the generalizability of the present study (and reduces the statistical power of the study). Furthermore, because viscoelastic testing was not used in this study, we do not know if lower preoperative fibrinogen levels result in deficient fibrinogen contribution to clot strength later during surgery (assessed, for example, using fibrinogen assays such as FIBTEM with rotational thromboelastometry, ROTEM). In summary, Carrier et al provide important insight into the role of fibrinogen in achieving hemostasis during and good outcomes after liver transplantation. Their data encourage us to check for fibrinogen levels whenever we measure conventional or viscoelastic coagulation tests and design future randomized trials of fibrinogen replacement in liver transplantation.

Predictive ability of viscoelastic testing using ClotPro® for short-term outcome in patients with severe Covid-19 ARDS with or without ECMO therapy: a retrospective study

BackgroundSARS-CoV-2 infections are suspected to trigger the coagulation system through various pathways leading to a high incidence of thromboembolic complications, hypercoagulation and impaired fibrinolytic capacity were previously identified as potentially mechanisms. A reliable diagnostic tool for detecting both is still under discussion. This retrospective study is aimed to examine the prognostic relevance of early viscoelastic testing compared to conventional laboratory tests in COVID-19 patients with acute respiratory distress syndrome (ARDS).MethodsAll mechanically ventilated patients with COVID-19 related ARDS treated in our intensive care unit (ICU) between January and March 2021 were included in this study. Viscoelastic testing (VET) was performed using the ClotPro® system after admission to our ICU. Prevalence of thromboembolic events was observed by standardized screening for venous and pulmonary thromboembolism using complete compression ultrasound and thoracic computed tomography pulmonary angiography at ICU admission, respectively. We examined associations between the severity of ARDS at admission to our ICU, in-hospital mortality and the incidence of thromboembolic events comparing conventional laboratory analysis and VET. ECMO related coagulopathy was investigated in a subgroup analysis. The data were analyzed using the Mann–Whitney U test.ResultsOf 55 patients enrolled in this study, 22 patients required treatment with ECMO. Thromboembolic complications occurred in 51% of all patients. Overall hospital mortality was 55%. In patients with thromboembolic complications, signs of reduced fibrinolytic capacity could be detected in the TPA assay with prolonged lysis time, median 460 s (IQR 350–560) vs 359 s (IQR 287–521, p = 0.073). Patients with moderate to severe ARDS at admission to our ICU showed increased maximum clot firmness as a sign of hypercoagulation in the EX-test (70 vs 67 mm, p < 0.05), FIB-test (35 vs 24 mm, p < 0.05) and TPA-test (52 vs 36 mm, p < 0.05) as well as higher values of inflammatory markers (CRP, PCT and IL6). ECMO patients suffered more frequently from bleeding complications (32% vs 15%).ConclusionAlthough, the predictive value for thromboembolic complications or mortality seems limited, point-of-care viscoelastic coagulation testing might be useful in detecting hypercoagulable states and impaired fibrinolysis in critically ill COVID-19 ARDS patients and could be helpful in identifying patients with a potentially very severe course of the disease.

Aspirin Administration Mitigates Platelet Hyperaggregability After Splenectomy in a Murine Model

IntroductionPatients who undergo splenectomy (SPLN) have an estimated 10%-35% risk of venous thromboembolic events; however, the underlying mechanism and strategy for prevention have yet to be identified. The goals of this study were to 1) investigate platelet aggregation after SPLN, 2) examine if aspirin administration could mitigate this effect, and 3) determine if concomitant hemorrhage would affect post-SPLN platelet function and response to aspirin. MethodsMurine models of operative SPLN and submandibular bleed (SMB) were utilized. Mice were randomized to eight groups as follows: untouched, SPLN, sham (laparotomy only), SMB, SPLN + SMB, SPLN + aspirin (ASA), SMB + ASA, and SPLN + SMB + ASA. Aspirin (50 mg/kg) was administered on postoperative days (PODs) one and two via oral gavage. Mice were euthanized on POD 3, platelet counts were obtained, and blood samples were analyzed via rotational thromboelastometry and impedance aggregometry with adenosine diphosphate (ADP) and arachidonic acid (AA) as agonists. ResultsBy POD 3, SPLN mice displayed a significant thrombocytosis compared to untouched, SMB, and sham SPLN mice. Clotting time and clot formation time were significantly decreased in SPLN and SPLN + SMB cohorts compared to untouched and sham controls with elevated mean clot firmness. SPLN mice also displayed a significant increase in ADP- and AA-mediated platelet aggregability compared to untouched controls, SMB, and SPLN + SMB. ASA significantly decreased platelet aggregation via both ADP and AA signaling in SPLN and SPLN + SMB cohorts without affecting viscoelastic coagulation testing. ConclusionsPlatelet hyperaggregability after SPLN is mediated by both ADP and AA signaling. Early aspirin administration may prevent increased platelet aggregation exacerbated after polytrauma.

Faster Time to Treatment Decision of Viscoelastic Coagulation Test Results through Improved Perception with the Animated Visual Clot: A Multicenter Comparative Eye-Tracking Study.

As the interpretation of viscoelastic coagulation test results remains challenging, we created Visual Clot, an animated blood clot aiming to facilitate raw rotational thromboelastometry (ROTEM) parameters. This study investigated anesthesia personnel’s cognitive processing in managing simulated bleeding scenarios using eye-tracking technology. This multicenter, international, computer-based study across five large, central European hospitals included 35 participants with minimal to no prior experience interpreting viscoelastic test results. Using eye-tracking technology and an iPad tagged with quick response codes, we defined the time to treatment decision and the time on screen surface in seconds of correctly solved scenarios as our outcomes. The median time to treatment decision was 52 s for Visual Clot and 205 s for ROTEM (p < 0.0001). The probability of solving the scenario correctly was more than 8 times higher when using Visual Clot than when using ROTEM (Hazard ratio [HR] 8.54, 95% CI from 6.5 to 11.21; p < 0.0001). Out of 194 correctly answered scenarios of participants with the eye-tracker, 154 (79.4%) were solved with Visual Clot and 40 (20.6%) with ROTEM. Participants spent on average 30 s less looking at the screen surface with Visual Clot compared to ROTEM (Coefficient −30.74 s, 95% CI from −39.27 to −22.27; p < 0.0001). For a comparison of the two modalities in terms of information transfer, we calculated the percentage of time on the screen surface of the overall time to treatment decision, which with Visual Clot was 14 percentage points shorter than with ROTEM (Coefficient −14.55, 95% CI from −20.05 to −9.12; p < 0.0001). Visual Clot seems to improve perception and detection of coagulopathies and leads to earlier initiation of the appropriate treatment. In a high-pressure working environment such as the operating and the resuscitation room, correct and timely decisions regarding bleeding management may have a relevant impact on patients’ outcomes.

Use of Citrated Whole Blood for Point-of-Care Viscoelastic Coagulation Testing in Dogs.

BackgroundA new, portable bedside coagulation monitor (VCM Vet) has provided a user-friendly, cartridge-based method to perform viscoelastic testing. However, the use of native whole blood limits the time to analyze the sample to minutes. The objective of this study is to assess whether citrated whole blood can be utilized with the cartridge-based system and whether the results are comparable to those of native whole blood. A secondary objective is to assess the viability of citrated whole blood results after up to 4 hours of resting.MethodsThe study population consisted of 10 healthy mixed breed dogs. Whole blood samples were collected via jugular venipuncture. Blood was immediately transferred to the VCM test cartridge for native whole blood control group analysis per the manufacturer's instructions, and the remainder was used to fill two 3.2% sodium citrate vacutainer tubes. Test group analysis was performed on samples from each tube concurrently after a rest period of 30 min (baseline), 2 h, and 4 h. Citrated whole blood samples were recalcified for analysis immediately prior to introduction into the test cartridge. Data was recorded for all reported parameters. Results from the citrate groups were compared to the control group and to the citrated baseline to assess for differences. Overall results were compared using mixed ANOVA models. Where found, specific differences were evaluated using Tukey's test. Within-sample variation was investigated and reported as median (range). A p < 0.05 was considered significant.ResultsSamples were obtained for a total of 10 control runs and 20 citrated whole blood runs. Comparison of controls to the citrated test groups revealed significant differences in CT (p < 0.001) and MCF (p < 0.002). There were no significant differences between test groups compared to citrated baselines for any parameter. Selected median coefficients of variation were 6.8% (0–68.8%) for CT, 2.4% (0–19.46%) for alpha angle, 3.2% (0–27.4%) for MCF, and 0% (0–16.3%) for 45-min LY45.ConclusionCitrated whole blood samples can be used with the VCM Vet device; however, new reference intervals for use with citrated whole blood will be required. Results using citrated whole blood samples are not significantly different from baseline after up to 4 h of resting.

Perioperative coagulation management during liver transplantation

ObjectivesThe aim was to make a systematic review of perioperative coagulation management during liver transplantation (LT).Data sourcesMedline databases (PubMed and Medscape) and all materials available on the Internet were searched., The search was performed on January 2022.Study selectionThe initial search presented 120 articles. The number of studies that met the inclusion criteria was 23. The articles included both sexes, diagnosed patients who needed LT.Data extractionIf the studies did not fulfill the inclusion criteria, they were excluded. Data from each eligible study were independently abstracted in duplicate using a data collection form to capture information on study characteristics, interventions, and quantitative results reported for each outcome of interest.Data synthesisSignificant data were collected. Then a structured review was performed.FindingIn total, 23 potentially relevant publications were included; it was found that early identification with clinical coagulation tests led to better understanding of coagulopathy using point-of-care viscoelastic coagulation tests as rotational thromboelastometry and thromboelastogram may improve outcomes of cirrhotic patients.ConclusionCirrhotic patients have unstable balance of coagulation. This results in a challenge to prevent risk of bleeding or thrombosis during LT. Recently, clinical coagulation tests have led to better understanding of coagulopathy using point-of-care viscoelastic coagulation tests such as rotational thromboelastometry and thromboelastogram. Future research is needed to better understand the complex coagulation balances and to improve goal-directed transfusion and factor concentrate treatment.

Comparison of the New Viscoelastic Coagulation Analyzer ClotPro® With ROTEM® Delta and Conventional Coagulation Tests in Critically Ill Patients With COVID-19.

Background: Viscoelastic coagulation testing has been suggested to help manage coagulopathy in critically ill patients with COVID-19. However, results from different viscoelastic devices are not readily comparable. ClotPro® is a novel thromboelastometry analyzer offering a wider range of commercially available assays.Methods: We compared the results from ClotPro with results from the well-established ROTEM® Delta device and conventional coagulation tests in critically ill patients with COVID-19.Results: Viscoelastic parameters indicated the presence of a potentially hypercoagulable state in the majority of patients. In up to 95 paired measurements, we found strong correlations between several parameters routinely used in clinical practice: (i) EX test vs. EXTEM CT, A5, A10, MCF, (ii) IN test vs. INTEM A5, A10, MCF, and (iii) FIB test vs. FIBTEM A5, A10, MCF (all R > 0.7 and p < 0.001). In contrast, IN test CT vs. INTEM CT showed only a moderate correlation (R = 0.53 and p < 0.001). Clot strength parameters of both devices exhibited strong correlations with platelet counts and fibrinogen levels (all R > 0.7 and p < 0.001). Divergent correlations of intrinsically activated assays with aPTT and anti-factor Xa activity were visible. Regarding absolute differences of test results, considerable delta occurred in CT, CFT, and clot strength parameters (all p < 0.001) between both devices.Conclusions: Several parameters obtained by ClotPro show strong correlations with ROTEM Delta. Due to weak correlations of intrinsically activated clotting times and considerable absolute differences in a number of parameters, our findings underline the need for device-specific algorithms in this patient cohort.

Point-of-care viscoelastic coagulation assessment in healthy dogs during the peri-anesthetic period

Introduction: Point-of-care viscoelastic coagulation testing has the potential to improve clinical management of anesthetized patients. The study aims were to evaluate serial viscoelastic coagulation monitor (VCM-Vet) analysis during the peri-anesthetic period in healthy dogs and compare the agreement between two VCM-Vet devices.

Impact of blood sampling technique on reproducibility of viscoelastic coagulation monitor (VCM™) system test results in the neonate

Purpose: To evaluate the reproducibility of the results of the viscoelastic coagulation test (VCT) performed with a new viscoelastic coagulation monitor (VCM™ – Entegrion) on native blood obtained by heel prick blood sampling with two different techniques compared to the standard blood collection in the newborn. Methods: Three blood samples were tested with the VCM analyzer in each of the 67 study subjects admitted to our level 3 neonatal intensive care unit. Standard blood collection (S) was performed by direct puncture of a peripheral vessel or by drawing of blood in a syringe connected to an arterial or venous catheter. Then, two more blood samples were drawn through a single heel prick. The first heel prick blood sample (HP1) was collected in the sample well through the attached metal capillary while the second (HP2) was poured directly into the sample well. Blood samples were automatically drawn into their pre-warmed cartridges and inserted into the VCM analyzers set up for analyses, which ran for one hour. VCT blood variables included clotting time (CT), clot formation time (CFT), angle alpha (α), amplitude at 10 and 20 min (A10 and A20), maximum clot firmness (MCF), and lysis indexes at 30 and 45 min (LY30 – LY45). Agreement was quantified by calculating the mean difference and SD between measurements of VCT blood variables from S, HP1 and HP2 blood samples. The 95% limits of agreement were calculated by the Bland & Altman method, using the upper or lower limit of agreement to interpret the variability of the measurements. The Kendall’s τ correlation coefficient evaluated the interdependence between SD and intra-measurement mean. Results: S blood samples were easily obtained in all the study subjects, while mild difficulties were recorded in 3/67 infants (4.5%) with the HP1 blood sampling and in 5/67 infants (7%) with the HP2 blood sampling. Pairwise comparison of test results performed on blood samples drawn with HP1 and HP2 techniques showed moderate agreement for CT and α-angle, strong agreement for CFT, LY30 and LY45 and almost perfect agreement for A10, A20 and MCF. In pairwise comparison of VCM analyses performed on blood samples drawn with S technique vs HP1 and HP2 techniques, Kendall’s τ correlation coefficient was significant for CT (S vs HP1 and HP1 vs HP2), CFT (S vs HP1 and S vs HP2), α-angle (S vs HP1) and MCF (S vs HP1). This suggests that the measurement error depends on the extent of the measurement. The overall ICC for blood sampling techniques ranged from 0.289 to 0.879 with best agreement observed for CFT (strong) and for A10, A20 and MCF (almost perfect). The LY30 index was the least repeatable measurement (poor agreement). The VCM analysis performed on the blood sample drawn with the HP1 technique showed the best repeatability compared with that performed with the S blood-sampling technique. Conclusion. VCT test results performed with the VCM analyzer on native blood drawn by heel prick in neonates are comparable to those obtained from standard blood samples. This could allow for a widespread, real-time assessment of the overall bedside haemostasis of these small patients.

Viscoelastic Coagulation Monitor (VCMVet) Reference Intervals and Sex Differences in Mature Adult Mice

Introduction: Viscoelastic coagulation tests are useful to assess coagulation status in the clinical setting and to aid in understanding underlying pathophysiological mechanisms that affect coagulation status. Such tests also are useful for coagulation research. Because mouse models are widely used to study molecular mechanisms in fine detail, a simple viscoelastic coagulation test requiring small blood volumes would be convenient for such studies in mice. Methods: We tested viscoelastic coagulation properties of normal healthy adult mice using a novel veterinary clinical point-of-care device, Viscoelastic Coagulation Monitor (VCM Vet™; Entegrion Corp.). Fresh whole blood was collected from 63 healthy mature adult C57 black 6N mice, with ultimately 54 mice, equal numbers of male and females, used to determine reference intervals (RIs) for VCM test parameters. Results: RIs were determined for equal numbers of male and female mice: clot time: 43.0–353.0 s; clot formation time: 49.4–137.6 s; alpha angle: 54.4–62.2°; A10: 25.0–49.6 VCM units; A20: 31.0–56.5 VCM units; maximum clot firmness: 37.6–62.8 VCM units; Lysis Index 30 (Li30): 99.8–100.0%; and Li45: 99.7–100.0%. Significant differences were found between male and female subgroups, where females had higher mean A10 and A20 and median MCF values, indicating greater clot firmness in female versus male mice. Conclusion: VCM Vet is a feasible viscoelastic coagulation test device for studies with mature adult mice, including studying inherent sex differences in coagulation parameters. Inherent differences in coagulability of male and female mice warrant further investigation to determine if such differences underlie greater coagulopathic, hemorrhagic, or thromboembolic risk during trauma or other pathophysiologic conditions.

Viscoelastic Coagulation Testing: Use and Current Limitations in Perioperative Decision-making.

Viscoelastic coagulation testing is increasingly used for clinical decision-making for targeted treatment of coagulopathy. Nevertheless, additional assays and studies are needed to define its role in coagulopathy management.