Thromboelastography does not predict outcome in different etiologies of cirrhosis

Predictors of membrane oxygenator failure in pediatric extracorporeal membrane oxygenation

BACKGROUND

Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is increasingly utilized in pediatric patients. Failure to recognize membrane oxygenator failure can lead to critical complications due to rapid deterioration of membrane oxygenator function. Therefore, identifying the predictors for membrane oxygenator exchange is crucial. However, risk factors for membrane oxygenator exchange in pediatric V-A ECMO remain unclear; therefore, this study aimed to evaluate these risk factors.

METHODS

This retrospective cohort study enrolled all pediatric patients aged <18 years who received V-A ECMO between August 2018 and July 2023 at a tertiary-care pediatric hospital in Japan. The Cox proportional hazards model was used to evaluate the predictors of membrane oxygenator failure within 72 h after initiation.

RESULTS

During the study period, membrane oxygenator failure occurred in 18/55 (32.7%) children within 72 h; membrane oxygenator failure within 72 h occurred in 4/29 (13.8%) and 14/26 (53.8%) in the groups with ratio of blood flow divided by the blood flow limit of the membrane oxygenator (B/L) of <0.5 and ≥0.5, respectively (adjusted hazards ratio, 4.97 [95% confidence interval, 1.33-18.5]; p = 0.017). After adjusting for delta pressure of the oxygenator, an increase in body weight and aspartate aminotransferase levels were associated with an increase in early membrane oxygenator failure.

CONCLUSIONS

This retrospective study demonstrated that a B/L ratio >0.5, an increase in body weight, and elevated aspartate aminotransferase were independent risk factors for early membrane oxygenator failure in pediatric V-A ECMO. However, a prospective multicenter study with an appropriate sample size is warranted to mitigate potential bias, and enhance generalizability for further investigation of the association between a B/L ratio and early membrane oxygenator failure.

Does the Use of Viscoelastic Hemostatic Assays for Periprocedural Hemostasis Management in Liver Disease Improve Clinical Outcomes?

Routine hemostasis parameters such as prothrombin time and fibrinogen are frequently abnormal in patients with chronic liver disease and have been demonstrated to be poor predictors for periprocedural bleeding. Alterations in procoagulant and anticoagulant factors in this population result in a state of rebalanced hemostasis, which is not reflected by routine hemostatic measures. Viscoelastic hemostatic assays (VHA) present a point of care measure of global hemostasis with an emerging role in guiding transfusion in the liver transplant setting. The potential role for VHA in guiding periprocedural transfusion is unknown. Here we critically appraise the available limited evidence on the use of VHA to guide prophylactic treatment in patients with cirrhosis undergoing procedures. We assess whether the impact of a VHA-guided approach improves clinical outcomes. Suggested areas for future research with a focus on clinically relevant outcomes, particularly periprocedural bleeding, are highlighted.

The Role of Viscoelastic Testing in Assessing Hemostasis: A Challenge to Standard Laboratory Assays?

Viscoelastic testing is increasingly being used in clinical and research settings to assess hemostasis. Indeed, there are potential situations in which viscoelastic testing is reportedly superior to standard routine laboratory testing for hemostasis. We report the current testing platforms and terminology, as well as providing a concise narrative review of the published evidence to guide its use in various clinical settings. Notably, there is increasing evidence of the potential utility of viscoelastic testing for assessment of direct oral anticoagulants, and bleeding associated with chronic liver disease, orthotopic liver transplantation, cardiac surgery, trauma, obstetrics and pediatrics.

Hypocoagulability in severe yellow fever infection is associated with bleeding: results from a cohort study

Background

Severe yellow fever infection (YFI) may be complicated by a hemorrhagic diathesis. However, the hemostasis profile of YFI has rarely been reported.

Objectives

The aim of this study was to characterize the hemostatic features of YFI by using a rotational thromboelastometry (ROTEM).

Methods

We evaluated clinical, laboratory, and ROTEM parameters in adults with severe YFI and their correlation with hemostatic variables according to bleeding and death.

Results

A total of 35 patients were included (median age, 49 years). ROTEM was performed in 22 patients, of whom 21 (96%) presented bleeding and 4 (18%) died. All patients who died had major bleeding. Patients who died presented prolonged clotting time (CT; median, 2326 seconds; IQR, 1898-2986 seconds) and reduced alpha angle (median, 12°; IQR, 12°-15°) in comparison with patients who had minor (median CT, 644 seconds; IQR, 552-845 seconds and alpha angle, 47°; IQR, 28°-65°) and major (median CT, 719 seconds; IQR, 368-1114 seconds and alpha angle, 43°; IQR, 32°-64°) bleeding who survived. In patients who had bleeding, CT showed a strong negative correlation with factor (F)V (r = -.68), FIX (r = -.84), and FX (r = -.63) as well as alpha angle showed a strong negative correlation with FIX (r = -.92). In patients who died, the correlations were even stronger. A total of 19/21 (90%) patients presented hypocoagulability assessed by ROTEM.

Conclusion

Hypocoagulabitity is the hallmark of the bleeding diathesis of severe YFI. Abnormal CT and alpha angle associated with death and could be used as potential predictors of adverse outcome in severe YFI.

A combination of clot formation abnormalities in thromboelastometry has a high prognostic value in patients with acute-on-chronic liver failure

BACKGROUND

Global coagulation tests offer a better tool to assess procoagulant and anticoagulant pathways, fibrinolysis and clot firmness and evaluate more accurately coagulation defects compared to conventional coagulation tests. Their prognostic role in acute-on-chronic liver disease (ACLF) or acute decompensation (AD) has not been well established.

AIMS

To assess the properties and prognostic value of the coagulation profile measured by rotational thromboelastometry (ROTEM) in ACLF and AD.

METHODS

84 consecutive patients (35 ACLF and 49 AD) were prospectively studied. Twenty healthy persons matched for age and gender were used as controls. 'Hypocoagulable' or 'hypercoagulable' profiles on admission were assessed based on nine ROTEM parameters and mortality was recorded at 30 and 90 days.

RESULTS

Individual ROTEM parameters denoted significantly more hypocoagulability in patients compared to controls. 'Hypocoagulable' profile (defined as a composite of 4 or more ROTEM parameters outside the range) was associated with more severe liver disease assessed either as MELD or Child-Pugh scores ( P  < 0.001 for both) and higher 30-day mortality (Log-rank P  = 0.012). 'Hypocoagulable' profile (HR 3.160, 95% CI 1.003-9.957, P  = 0.049) and ACLF status (HR 23.786, 95% CI 3.115-181.614, P  = 0.002) were independent predictors of 30-day mortality, in multivariate model. A higher early mortality rate was shown in ACLF patients with 'hypocoagulable' phenotype compared to those without (Log-rank P  = 0.017). 'Hypocoagulable' profile was not associated with mortality in AD.

CONCLUSION

'Hypocoagulable' profile was associated with more advanced liver disease and higher short-term mortality in patients with ACLF.

Serial rotational thromboelastometry measurements show worsening hypocoagulability in acute-on-chronic liver failure and are associated with the severity of liver disease

Background

Viscoelastic tests are used to better understand the complex picture of hemostasis in cirrhosis. Limited data exist regarding the clinical relevance of rotational thromboelastometry (ROTEM) in acute-on-chronic liver failure (ACLF) or acute decompensation (AD). We examined the pattern and role of sequential observations of 9 ROTEM components in both ACLF and AD groups.

Method

ROTEM measurements were compared within and between groups at 3 time points: on admission (T1), at 24 h (T2) and 48 h post-admission (T3).

Results

Forty-two consecutive patients (22 ACLF, 20 AD) were included. ROTEM determinants exhibited significant hypocoagulable deterioration in ACLF but not in AD over the 3 time points in clot formation time (CFT)EXTEM (P=0.01), maximum clot firmnessEXTEM (P=0.014), CFTINTEM (P<0.001), and alphaINTEM (P=0.028). The sum of hypocoagulable determinants increased from T1 to T3 in ACLF (P=0.029), but remained stable in AD. Five ROTEM variables showed significant differences towards hypocoagulability in ACLF compared to AD at T3. A "hypocoagulable" profile was associated with more severe liver disease (P<0.001 for model for end-stage liver disease [MELD] or Child-Pugh scores) and higher 30- and 90-day mortality (log-rank P=0.001 and P=0.013, respectively) but no more bleeding episodes or transfusions. Two ROTEM variables displayed strong correlations with MELD at T1 and 7 at T3 (|r coefficient|>0.5).

Conclusions

ROTEM measurements indicated worsening hypocoagulability shortly post-admission compared to baseline in ACLF, but remained stable in AD. The hypocoagulable derangement was mostly correlated with the severity of liver disease and higher short-term mortality, but not more bleeding episodes.

Viscoelastic Testing Methods

Viscoelastic testing methods examine the real-time formation of a clot in a whole blood sample, and include thromboelastography (TEG), rotational thromboelastometry (ROTEM), and several other testing platforms. They allow for concurrent assessment of multiple aspects of clotting, including plasmatic coagulation factors, platelets, fibrinogen, and the fibrinolytic pathway. This testing is rapid and may be performed at the point-of-care, allowing for prompt identification of coagulopathies to guide focused and rational administration of blood products as well as the identification of anticoagulant effect. With recent industry progression towards user-friendly, cartridge-based, portable instruments, viscoelastic testing has emerged in the 21st century as a powerful tool to guide blood transfusions in the bleeding patient, and to identify and treat both bleeding and thrombotic conditions in many operative settings, including trauma surgery, liver transplant surgery, cardiac surgery, and obstetrics. In these settings, the use of transfusion algorithms guided by viscoelastic testing data has resulted in widespread improvements in patient blood management as well as modest improvements in select patient outcomes. To address the increasingly wide adoption of viscoelastic methods and the growing number of medical and laboratory personnel tasked with implementing, performing, and interpreting these methods, this chapter provides an overview of the history, physiology, and technology behind viscoelastic testing, as well as a practical review of its clinical utility and current evidence supporting its use. Also included is a review of testing limitations and the contextual role played by viscoelastic methods among all coagulation laboratory testing.

Fibrin clot properties and thrombus composition in cirrhosis

Patients with cirrhosis frequently acquire profound hemostatic alterations, which may affect thrombus quality and composition-factors that determine the susceptibility to embolization and fibrinolysis. In this narrative review, we describe in vitro studies on fibrin clot formation and quantitative and qualitative changes in fibrinogen in patients with cirrhosis, and describe recent findings on the composition of portal vein thrombi in patients with cirrhosis. Patients with mild cirrhosis have increased thrombin generation capacity and plasma fibrinogen levels, which may be balanced by delayed fibrin polymerization and decreased factor XIII levels. With progressing illness, plasma fibrinogen levels decrease, but thrombin generation capacity remains elevated. Fibrinogen is susceptible to posttranslational protein modifications and is, for example, hypersialylated and carbonylated in patients with cirrhosis. Despite changes in thrombin generation, factor XIII levels and the fibrinogen molecule, fibrin fiber thickness, and density are normal in patients with cirrhosis. Paradoxically, fibrin clot permeability in patients with cirrhosis is decreased, possibly because of posttranslational protein modifications. Most patients have normal fibrinolytic potential. We have recently demonstrated that portal vein thrombosis is likely a misnomer as the material that may obstruct the cirrhotic portal vein frequently consists of a thickened portal vein wall, rather than a true thrombus. Patients with cirrhosis often have thrombocytopenia and anemia, which may also affect clot stability and composition, but the role of cellular components in clot quality in cirrhosis has not been extensively studied. Finally, we summarize abstracts on fibrin formation and clot quality that were presented at the ISTH 2022 meeting in London.

Review article: thromboelastography in liver diseases

BACKGROUND

Patients with liver diseases have complicated haemostatic alternations, resulting in both bleeding and thromboembolic complications, which cannot be sufficiently evaluated by conventional coagulation tests (CCTs), such as platelet count or prothrombin time. Thromboelastography (TEG) is a whole blood viscoelastic test which globally reflects changes in the haemostatic system, and its utility in evaluating patients with liver disease is increasingly recognised.

AIMS

To review the current evidence and clinical significance of TEG in liver diseases.

METHODS

Literature regarding TEG and liver diseases was comprehensively searched.

RESULTS

TEG is associated closely with the severity and aetiology of liver disease, the course of infection and the risk of bleeding and death, but not the risk of portal venous system thrombosis. Additionally, TEG-guided transfusion protocols can significantly decrease the requirement for blood products compared to those guided by CCTs.

CONCLUSION

TEG can reflect the haemostatic status of liver diseases more comprehensively than CCTs. It has the potential to assess the severity of liver diseases, predict the risk of bleeding and death in patients with liver disease and guide blood product transfusion. Future studies should standardise the use of TEG for assessing disease severity and development of clinical events and guiding blood product transfusion in patients with liver diseases.

Pathophysiology and management of bleeding and thrombosis in patients with liver disease

Patients with liver disease often develop complex changes in their haemostatic system. Frequently observed changes include thrombocytopaenia and altered plasma levels of most of the proteins involved in haemostasis. Although liver disease was historically classified as a haemostasis‐related bleeding disorder, it has now been well established that the antihaemostatic changes that promote bleeding are compensated for by prohaemostatic changes. Conventional coagulation tests however do not accurately reflect these prohaemostatic changes, resulting in an underestimation of haemostatic potential. Novel coagulation tests, such as viscoelastic tests (VETs) and thrombin generation assays (TGAs) better reflect the net result of the haemostatic changes in patients with liver disease, and demonstrate a new, “rebalanced” haemostatic status. Although rebalanced, this haemostatic status is more fragile than in patients without liver disease. Patients with liver disease are therefore not only at risk of bleeding but also at risk of thrombosis. Notably, however, many haemostatic complications in liver disease are not related to the haemostatic failure. It is, therefore, crucial to identify the cause of the bleed or thrombotic complication in order to provide adequate treatment. In this paper, we will elaborate on the haemostatic changes that occur in liver disease, reflect on laboratory and clinical studies over the last few years, and explore the pathophysiologies of bleeding and thrombosis in this specific patient group.

Effects of Inflammation on Hemostasis in Acutely Ill Patients with Liver Disease

Patients with liver diseases are in a rebalanced state of hemostasis, due to simultaneous decline in pro- and anticoagulant factors. This balance seems to remain even in the sickest patients, but is less stable and might destabilize when patients develop disease complications. Patients with acute decompensation of cirrhosis, acute-on-chronic liver failure, or acute liver failure often develop complications associated with changes in the hemostatic system, such as systemic inflammation. Systemic inflammation causes hemostatic alterations by adhesion and aggregation of platelets, release of von Willebrand factor (VWF), enhanced expression of tissue factor, inhibition of natural anticoagulant pathways, and inhibition of fibrinolysis. Laboratory tests of hemostasis in acutely-ill liver patients may indicate a hypocoagulable state (decreased platelet count, prolongations in prothrombin time and activated partial thromboplastin time, decreased fibrinogen levels) due to decreased synthetic liver capacity or consumption, or a hypercoagulable state (increased VWF levels, hypofibrinolysis in global tests). Whether these changes are clinically relevant and should be corrected with antithrombotic drugs or blood products is incompletely understood. Inflammation and activation of coagulation may cause local ischemia, progression of liver disease, and multiorgan failure. Anti-inflammatory treatment in acutely-ill liver patients may be of potential interest to prevent thrombotic or bleeding complications and halt progression of liver disease.

Hemostasis testing in patients with liver dysfunction: Advantages and caveats

Due to concomitant changes in pro- and anti-coagulant mechanisms, patients with liver dysfunction have a “rebalanced hemostasis”, which can easily be tipped toward either a hypo- or a hypercoagulable phenotype. Clinicians are often faced with the question whether patients with chronic liver disease undergoing invasive procedures or surgery and those having active bleeding require correction of the hemostasis abnormalities. Conventional coagulation screening tests, such as the prothrombin time/international normalized ratio and the activated partial thromboplastin time have been demonstrated to have numerous limitations in these patients and do not predict the risk of bleeding prior to high-risk procedures. The introduction of global coagulation assays, such as viscoelastic testing (VET), has been an important step forward in the assessment of the overall hemostasis profile. A growing body of evidence now suggests that the use of VET might be of significant clinical utility to prevent unnecessary infusion of blood products and to improve outcomes in numerous settings. The present review discusses the advantages and caveats of both conventional and global coagulation assays to assess the risk of bleeding in patients with chronic liver disease as well as the current role of transfusion and hemostatic agents to prevent or manage bleeding.

The strengths and weaknesses of viscoelastic testing compared to traditional coagulation testing

Optimized acute bleeding management requires timely and reliable laboratory testing to detect and diagnose coagulopathies and guide transfusion therapy. Conventional coagulation tests (CCT) are inexpensive with minimal labor requirements, but CCTs may have delayed turnaround times. In addition, abnormal CCT values may not reflect in vivo coagulopathies that require treatment and may lead to overtransfusion. The use of viscoelastic testing (VET) has been rapidly expanding and is recommended by several recent bleeding guidelines. This review is intended to compare CCT to VET, review the strengths and weaknesses of both approaches, and evaluate and summarize the clinical studies that compared CCT-based and VET-based transfusion algorithms. Most studies of CCT vs VET transfusion algorithms favor the use of VET in the management of massively bleeding patients due to reductions in blood product utilization, bleeding, costs, and lengths of stay.

Viscoelastic tests in liver disease: where do we stand now?

Hemostasis is a complex physiological process based on the balance between pro-coagulant and anticoagulant systems to avoid pathological bleeding or thrombosis. The changes in standard coagulation tests in liver disease were assumed to reflect an acquired bleeding disorder, and cirrhotic patients were considered naturally anticoagulated. In the light of the new evidence, the theory of rebalanced hemostasis replaced the old concept. According to this model, the hemostatic alteration leads to a unique balance between pro-coagulant, anticoagulant, and fibrinolytic systems. But the balance is fragile and may prone to bleeding or thrombosis depending on various risk factors. The standard coagulation tests [INR (international normalized ratio), platelet count and fibrinogen] only explore parts of the hemostasis, not offering an entire image of the process. Rotational thromboelastometry (ROTEM) and thromboelastography (TEG) are both point of care viscoelastic tests (VET) that provide real-time and dynamic information about the entire hemostasis process, including clot initiation (thrombin generation), clot kinetics, clot strength, and clot stability (lysis). Despite prolonged PT/INR (international normalized ratio of prothrombin time) and low platelet counts, VET is within the normal range in many patients with both acute and chronic liver disease. However, bleeding remains the dominant clinical issue in patients with liver diseases, especially when invasive interventions are required. VET has been shown to asses more appropriately the risk of bleeding than conventional laboratory tests, leading to decrial use of blood products transfusion. Inappropriate clotting is common but often subtle and may be challenging to predict even with the help of VET. Although VET has shown its benefit, more studies are needed to establish cut-off values for TEG and ROTEM in these populations and standardization of transfusion guidelines before invasive interventions in cirrhotic patients/orthotopic liver transplantation.

Reduced Clot Stability by Thromboelastography as a Potential Indicator of Procedure-Related Bleeding in Decompensated Cirrhosis

In patients with decompensated cirrhosis, procedure-related bleeding is a potentially lethal complication. Routine coagulation tests such as international normalized ratio and platelet count do not predict bleeding risk. We investigated whether thromboelastography (TEG) can identify patients with cirrhosis who are at risk of procedure-related bleeding. As a part of a prospective study on hemostasis in decompensated cirrhosis, patients had TEG performed on admission and were followed prospectively during hospitalization for the development of procedure-related bleeding. Eighty patients with cirrhosis were included. Among the 72 who had procedures performed, 7 had procedure-related bleeding, which was major in three cases (two following paracentesis and one following thoracentesis). Conventional coagulation tests were comparable between bleeding and nonbleeding patients, whereas TEG parameters of k-time (4.5 minutes vs. 2.2 minutes; P = 0.02), α-angle (34° vs. 59°; P = 0.003), and maximum amplitude (37 mm vs. 50 mm; P = 0.004) were significantly different (all indicative of hypocoagulability). TEG maximum amplitude (MA), a marker of overall clot stability, accurately discriminated between patients who had major, life-threatening bleeding (all with MA < 30 mm) and those who had mild or no bleeding (all with MA > 30 mm), whereas a platelet count < 50 × 109/L could not discriminate between bleeding (minor or major) and nonbleeding patients. Conclusion: In a prospective cohort of hospitalized patients with decompensated cirrhosis, TEG parameters associated with hypocoagulability appeared to predict procedure-related bleeding, particularly a TEG MA < 30 mm. If results are validated in a larger cohort, this could be a threshold to identify patients with decompensated cirrhosis at higher risk for procedure-related bleeding, in whom to consider preprocedural prophylaxis.

Features of Blood Clotting on Thromboelastography in Hospitalized Patients With Cirrhosis

INTRODUCTION

Thromboelastography (TEG) provides a global assessment of hemostasis and may have value for patients with cirrhosis who have multiple hemostatic defects. We sought to examine the characteristics of TEG in hospitalized patients with cirrhosis and its relationship with outcomes.

METHODS

We performed a cohort study of all adults with cirrhosis hospitalized at Indiana University Hospital between November 2015 and October 2018 with a TEG. We examined the relationships among TEG, traditional measures of hemostasis, liver disease severity, and outcomes, including mortality, discharge to hospice, length of stay, and 30-day readmission.

RESULTS

A total of 344 patients met inclusion and exclusion criteria. R-value was elevated (≥10 min) in 4.5%, alpha angle was low (<45°) in 9.3%, and maximum amplitude (maximum amplitude) was low (<55 mm) in 72.1%. K-value, alpha angle, and maximum amplitude were all correlated with both platelet count and fibrinogen (absolute rho range 0.52-0.67); R-value and international normalized ratio (INR) were not strongly correlated with traditional measures or TEG, respectively. Patients with bleeding had hypercoagulable profiles, and patients with infection had increased R-value and decreased alpha angle. A total of 35.8% died or were discharged to hospice, and these patients had a greater R-value and smaller alpha angle. However, after adjustment for model for end-stage liver disease (MELD), neither R-value nor alpha angle were associated with discharge outcomes.

CONCLUSIONS

TEG provides insight into the hemostatic state of patients with cirrhosis beyond that of standard measures of hemostasis. It is associated with liver disease severity and outcomes and may play a role complementary to standard measures of hemostasis in this population.

Thromboelastometry in patients with advanced chronic liver disease stratified by severity of portal hypertension

Background

Rotational thromboelastometry (ROTEM) has been studied in patients with advanced chronic liver disease (ACLD) without considering the impact of portal hypertension. We evaluated the influence of the hepatic venous pressure gradient (HVPG) on ROTEM results in patients with ACLD.

Methods

Cross-sectional study; ACLD patients undergoing HVPG measurement within the prospective Vienna Cirrhosis Study (NCT03267615) underwent concomitant ROTEM testing.

Results

Among 159 patients (68% male; Child–Pugh-A: 53%, Child–Pugh-B: 34%, Child–Pugh-C: 13%), 21 patients (13%) had a HVPG between 6 and 10 mmHg, 84 patients (53%) between 10 and 19 mmHg, and 54 patients (34%) ≥ 20 mmHg. Child–Pugh-C patients (vs. Child–Pugh-A and vs. Child–Pugh-B patients, respectively) showed longer clot formation time (CFT: median 187 s vs. 122 s vs. 122 s, p = 0.007) and lower maximum clot firmness (MCF: median: 45 mm vs. 56 mm vs. 56 mm, p = 0.002) in extrinsic thromboelastometry (EXTEM), while platelet counts were similar across Child–Pugh stages. In the overall cohort, ROTEM parameters did not differ by severity of portal hypertension. However, among compensated Child–Pugh-A patients, MCF decreased with increasing portal pressure, i.e. in higher HVPG strata (HVPG 9–10 mmHg: median MCF: 59 mm vs. HVPG 10–19 mmHg: 56 mm vs HVPG ≥ 20 mmHg: 54 mm, p = 0.023). Furthermore, patients with short CFT and high MCF in EXTEM had higher levels of lipopolysaccharide-binding protein, C-reactive protein, and procalcitonin, as well as higher leukocyte counts (all p < 0.05).

Conclusions

Portal hypertension seems to impact ROTEM results only in compensated Child–Pugh-A patients. Bacterial translocation and systemic inflammation may trigger a procoagulant state in patients with ACLD.

Electronic supplementary material

The online version of this article (10.1007/s12072-020-10093-3) contains supplementary material, which is available to authorized users.

New Uses for Thromboelastography and Other Forms of Viscoelastic Monitoring in the Emergency Department: A Narrative Review

Patients frequently visit the emergency department with conditions that place them at risk of worse outcomes when accompanied by coagulopathy. Routine tests of coagulation-prothrombin time, partial thromboplastin time, platelets, and fibrinogen-have shortcomings that limit their use in providing emergency care. One alternative is to investigate coagulation disturbance with viscoelastic monitoring (VEM), a coagulation test that measures the timing and strength of blood clot development in real time. VEM is widely used and studied in cardiac surgery, liver transplant surgery, anesthesia, and trauma. In this article, we review the technique of VEM and the biologic rationale of using it in addition to routine tests of coagulation in emergency clinical situations. Then, we review the evidence (or lack thereof) for using VEM in the diagnosis and treatment of specific conditions. Finally, we describe the limitations of the test and future directions for clinical use and research in emergency medicine.

Viscoelastic Tests as Point-of-Care Tests in the Assessment and Management of Bleeding and Thrombosis in Liver Disease

Viscoelastic point-of-care (VET POC) tests provide a global assessment of hemostasis and have an increasing role in the management of bleeding and blood component delivery across several clinical settings. VET POC tests have a rapid turnaround time, provide a better overall picture of hemostasis, predict bleeding more accurately than conventional coagulation tests, and reduce blood component usage and health care costs. Despite commonly having abnormal conventional coagulation tests, most patients with chronic liver disease have a "rebalanced" hemostasis. However, this hemostatic balance is delicate and these patients are predisposed to both bleeding and thromboembolic events. Over recent years, VET POC tests have been increasingly studied for their potential as better functional tests of hemostasis in liver disease patients. This review provides a background on the most common VET POC tests (thromboelastography and rotational thromboelastometry) and discusses the current evidence for these tests in the prediction and management of bleeding and thrombosis in patients with chronic liver disease, and in liver resection and transplant. With the recent publication of several randomized controlled trials, there is growing evidence that VET POC tests may be used to improve bleeding risk assessment and reduce blood product use in liver disease patients outside of the transplant setting. However, consensus is still lacking regarding the VET POC tests' thresholds that should be used to trigger blood product transfusion. VET POC tests also show promise in predicting thrombosis in patients with liver disease, but further research is needed before they can be used to guide anticoagulant therapy.

Standard coagulation tests are superior to thromboelastometry in predicting outcome of patients with liver cirrhosis

Background and aims

Thromboelastometry (TEM) is superior to standard coagulation tests in the management of bleedings / invasive procedures in patients with liver cirrhosis. In contrast, the role of TEM as a prognostic parameter in liver cirrhosis is not well established. We therefore aimed to assess the role of TEM in predicting survival of outpatients with liver cirrhosis.

Methods

TEM was performed in consecutive outpatients with liver cirrhosis admitted in 2018 and 2019 to the University Hospital Essen. Associations with transplant-free survival were assessed in regression models.

Results

A number of 145 outpatients with liver cirrhosis were included, of whom 27 received a liver transplant (N = 7) or died (N = 20) within 6 months of follow-up. None of the TEM values was associated with transplant-free survival in this cohort. However, as expected, the classical coagulation tests INR (OR = 8.69 (95% CI 1.63–46.48), P = 0.01), PTT (OR = 1.15 (95% CI 1.04–1.27), P<0.01), as well as antithrombin (OR = 0.96 (95% CI 0.94–0.99), P<0.01), and protein C (OR = 0.96 (95% CI 0.92–0.99), P<0.01) were significantly associated with transplant-free survival.

Conclusion

In contrast to the superiority of TEM over classical coagulation tests to guide transfusion of blood products in patients with liver cirrhosis, TEM has no relevance in predicting mortality in outpatients with liver cirrhosis.

Tracing the Lines: A Review of Viscoelastography for Emergency Medicine Clinicians

BACKGROUND

Viscoelastography (VE) is an established method to identify coagulopathies in various disease processes. Clinical decisions can be made with real-time tracings and quantitative values at the bedside. Thromboelastography (TEG®) and rotational thromboelastometry (ROTEM®) have been utilized in several disease states with clinical varying success.

OBJECTIVES

This review will summarize the literature and provide recommendations pertaining to major disease processes where VE may be beneficial, including trauma, anticoagulation reversal, liver disease, acute ischemic stroke, and acquired brain injuries.

DISCUSSION

VE has a role in many emergency medicine patients encountered by clinicians. Reduced mortality, decreased blood product utilization, and prognostication ability makes VE an intriguing tool that can be utilized by providers to improve patient care.

CONCLUSION

This review serves as a way for emergency medicine clinicians to utilize VE in their practice and provides an insightful literature overview.

Primary Hemostasis in Chronic Liver Disease and Cirrhosis: What Did We Learn over the Past Decade?

Changes in primary hemostasis have been described in patients with chronic liver disease (CLD) and cirrhosis and are still subject to ongoing debate. Thrombocytopenia is common and multifactorial. Numerous studies also reported platelet dysfunction. In spite of these changes, primary hemostasis seems to be balanced. Patients with CLD and cirrhosis can suffer from both hemorrhagic and thrombotic complications. Variceal bleeding is the major hemorrhagic complication and is mainly determined by high portal pressure. Non portal hypertension-related bleeding due to hemostatic failure is uncommon. Thrombocytopenia can complicate management of invasive procedures in CLD patients. Recently, oral thrombopoietin agonists have been approved to raise platelets before invasive procedures. In this review we aim to bundle literature, published over the past decade, discussing primary hemostasis in CLD and cirrhosis including (1) platelet count and the role of thrombopoietin (TPO) agonists, (2) platelet function tests and markers of platelet activation, (3) von Willebrand factor and (4) global hemostasis tests.

Whole blood thrombin generation profiles of patients with cirrhosis explored with a near patient assay

BACKGROUND AND AIMS

Patients with cirrhosis have a rebalanced hemostasis, often with normal or elevated thrombin-generating (TG) capacity in plasma. Whole blood (WB) TG allows faster determination and, importantly, includes the influence of all circulating blood cells. We aimed to study the TG profile of patients with cirrhosis in WB and in platelet poor plasma.

METHODS

Thrombin-generating capacity in WB and plasma were assessed with a near-patient WB-TG assay and the calibrated automated thrombinography assay, respectively. TG assays were tested in presence and absence of thrombomodulin. Conventional coagulation tests were also performed.

RESULTS

Thirty-four patients with cirrhosis and twenty-two controls were analyzed. Compared with controls, patients had substantially deranged results in conventional coagulation tests. Comparable WB-TG capacity (endogenous thrombin potential until peak, ETPp) but significantly lower peak thrombin were found in patients, and these results persisted when thrombomodulin was present. TG of the patients was more resistant to thrombomodulin than controls in both WB and plasma, although the inhibitory effect of thrombomodulin was drastically weaker in WB than in plasma. The peak of WB-TG in patients correlated moderately with their hematocrit and platelet count. Significant correlations were found between TG results in WB and plasma.

CONCLUSIONS

The WB-TG assay shows a normal to hypocoagulable state in patients with cirrhosis with a decreased anticoagulant activity of TM compared to plasma-TG. The clinical value of this assay needs further validation.

Relationship of thromboelastography and conventional clotting test values with severe bleeding in critically ill patients with coagulopathy: A prospective study

INTRODUCTION

This study aimed to ascertain the associations of thromboelastography (TEG^® ) and standard laboratory test (SLTs) values with the presence of bleeding in critically ill patients with known coagulopathy.

METHODS

Three groups of coagulopathic patients with (a) hepatic failure, (b) postoperative period after prolonged cardiac surgery, and (c) complex abdominal surgery with sepsis were prospectively included in this study. On intensive care unit (ICU) admission, patients were stratified into two groups according to whether they had major bleeding (MB) (evident overt bleeding, important bleeding apparent on imaging studies, and/or need for moderate-massive blood transfusion and hemodynamic instability). Blood samples were drawn for the SLTs (international normalized ratio [INR], activated partial thromboplastin time [aPTT], platelet count, and fibrinogen level [Clauss]) and TEG whole blood coagulation assays. Receiver operating characteristic (ROC) curves were generated to determine the efficiency of TEG and SLTs for detecting bleeding. The correlations between SLTs and TEG parameters with similar coagulation profiles were evaluated by Spearman rank-order analysis.

RESULTS

Eighty-three patients were included, and bleeding was confirmed in 45 (54%). The fibrinogen level demonstrated the best accuracy for detecting bleeding with an area under the curve and 95% confidence intervals [AUC (95% CI)] of 0.74 (0.63-0.85) with the best cutoff value of ≤ 2 g/L. Regarding TEG-MA, the AUC (CI) obtained with the optimal cutoff value of ≤ 51 mm was 0.68 (0.56-0.80).

CONCLUSIONS

Both conventional clotting tests and TEG values were poorly associated with bleeding in this critically ill cohort of patients with coagulopathy.

Successful management of refractory bleeding in liver failure with tranexamic acid: Case report and literature review

A 50-year-old woman with advanced cirrhosis presented with spontaneous subdural hematoma. She had a worsening clinical course following craniotomy despite administration of multiple blood products. With elevation in D-dimer, persistently low fibrinogen and poor response to factor/fibrinogen replacement therapies, we had a suspicion for uncontrolled fibrinolysis. A literature review was conducted on treatment of hyperfibrinolysis in cirrhosis, finding 4 reports in which antifibrinolytics were used to control bleeding with different outcomes. The dose of tranexamic acid used in our patient was employed from previous experience in trauma patients. We transitioned from intravenous to oral administration based on expected pharmacokinetics. Our patient had a successful outcome with resolution of bleeding.

The Misunderstood Coagulopathy of Liver Disease: A Review for the Acute Setting

The international normalized ratio (INR) represents a clinical tool to assess the effectiveness of vitamin-K antagonist therapy. However, it is often used in the acute setting to assess the degree of coagulopathy in patients with hepatic cirrhosis or acute liver failure. This often influences therapeutic decisions about invasive procedures or the need for potentially harmful and unnecessary transfusions of blood product. This may not represent a best-practice or evidence-based approach to patient care. The author performed a review of the literature related to the utility of INR in cirrhotic patients using several scientific search engines. Despite the commonly accepted dogma that an elevated INR in a cirrhotic patient corresponds with an increased hemorrhagic risk during the performance of invasive procedures, the literature does not support this belief. Furthermore, the need for blood-product transfusion prior to an invasive intervention is not supported by the literature, as this practice increases the risk of complications associated with a patient's hospital course. Many publications ranging from case studies to meta-analyses refute this evidence and provide examples of thrombotic events despite elevated INR values. Alternative methods, such as thromboelastogram, represent alternate means of assessing in vivo risk of hemorrhage in patients with acute or chronic liver disease in real-time in the acute setting.