Rotation thromboelastometry detects thrombocytopenia and hypofibrinogenaemia during orthotopic liver transplantation

The role of viscoelastic hemostatic assays for postpartum hemorrhage management and bedside intrapartum care

Viscoelastic hemostatic assays are point-of-care devices that assess coagulation and fibrinolysis in whole blood samples. These technologies provide numeric and visual information of clot initiation, clot strength, and clot lysis under low-shear conditions, and have been used in a variety of clinical settings and subpopulations, including trauma, cardiac surgery, and obstetrics. Emerging data indicate that these devices are useful for detecting important coagulation defects during major postpartum hemorrhage (especially low plasma fibrinogen concentration [hypofibrinogenemia]) and informing clinical decision-making for blood product use. Data from observational studies suggest that, compared with traditional formulaic approaches to transfusion management, targeted or goal-directed transfusion approaches using data from viscoelastic hemostatic assays are associated with reduced hemorrhage-related morbidity and lower blood product requirement. Viscoelastic hemostatic assays can also be used to identify and treat coagulation defects in patients with inherited or acquired coagulation disorders, such as factor XI deficiency or immune-mediated thrombocytopenia, and to assess hemostatic profiles of patients prescribed anticoagulant medications to mitigate the risk of epidural hematoma after neuraxial anesthesia and postpartum hemorrhage after delivery.

Coagulation management during liver transplantation: monitoring and decision making for hemostatic interventions

PURPOSE OF REVIEW

Rebalanced hemostasis describes the precarious balance of procoagulant and antithrombotic proteins in patients with severe liver failure. This review is aimed to discuss currently available coagulation monitoring tests and pertinent decision-making process for plasma coagulation factor replacements during liver transplantation (LT).

RECENT FINDINGS

Contemporary viscoelastic coagulation monitoring systems have demonstrated advantages over conventional coagulation tests in assessing the patient's coagulation status and tailoring hemostatic interventions. There is increasing interest in the use of prothrombin complex and fibrinogen concentrates, but it remains to be proven if purified factor concentrates are more efficacious and safer than allogeneic hemostatic components. Furthermore, the decision to use antifibrinolytic therapy necessitates careful considerations given the risks of venous thromboembolism in severe liver failure.

SUMMARY

Perioperative hemostatic management and thromboprophylaxis for LT patients is likely to be more precise and patient-specific through a better understanding and monitoring of rebalanced coagulation. Further research is needed to refine the application of these tools and develop more standardized protocols for coagulation management in LT.

A look into hemostatic characteristics during pediatric liver transplantation using the thromboelastometry (ROTEM® ) test

There is a paucity of evidence about the coagulation profile regarding the complexity of children undergoing liver transplantation (LT). This study aimed to investigate intraoperative hemostatic changes during pediatric LT according to the etiology for LT and examine the ability of rotational thromboelastometry (ROTEM^® , TEM International GmbH, Munich, Germany) as a point-of-care monitoring method. We evaluated 106 patients aged 3 months to 17 years undergoing LT for acute liver failure (ALF) and chronic liver disease, which consists of patients with cholestatic disease, metabolic/genetic disease, and cancer. A total of 731 ROTEM^® measurements, including 301 ellagic acid to initiate clotting via the intrinsic pathway, 172 tissue factor to initiate the extrinsic clotting cascade (EXTEM), and 258 cytochalasin D to inhibit platelet activity reflecting fibrinogen (FIBTEM), were analyzed at predetermined time points (the preanhepatic, anhepatic, and postreperfusion phases). We simultaneously conducted conventional coagulation tests. In children with ALF, preanhepatic measurements of conventional coagulation tests and ROTEM^® showed a more hypocoagulable state than other diseases. During LT, the coagulation profile was deranged, with a prolonged clotting time and reduced clot firmness, changes that were more profound in the cholestatic disease group. Maximum clot firmness (MCF) on EXTEM and FIBTEM were well correlated with the platelet count and fibrinogen concentration (r = 0.830, p < 0.001 and r = 0.739, p < 0.001, respectively). On the EXTEM, MCF with 30 mm predicted a platelet count <30,000/mm³ (area under the curve, 0.985), and 6 mm predicted a fibrinogen concentration <100 mg/dl on the FIBTEM (area under the curve, 0.876). However, the activated partial thromboplastin time and prothrombin time were significant but only weakly correlated with the clotting time on the ROTEM^® . In children undergoing LT, coagulation profiles depend on the etiology for LT. During LT, ROTEM^® parameters could help detect thrombocytopenia and hypofibrinogenemia and guide transfusion therapy as a point-of-care monitoring method.

Evaluation of novel coagulation and platelet function assays in patients with chronic kidney disease

BACKGROUND

Hemostasis evaluation in chronic kidney disease (CKD) is critical for optimal management of thrombotic and bleeding events. Standard coagulation screens are inadequate for predicting coagulopathy in CKD.

OBJECTIVE

To evaluate hemostasis parameters in patients with different stages of CKD using novel coagulation assays.

PATIENTS/METHODS

Cross-sectional study of 30 healthy controls (HC) and 120 CKD patients (10 Stage 2, 20 Stage 3, 20 Stage 4, 20 Stage 5 not requiring renal replacement therapy, 20 transplant, 10 newly started on hemodialysis [HD], 20 established on HD). Standard laboratory tests were performed in addition to rotational thromboelastometry (ROTEM), multiple electrode aggregometry (MEA), thrombin generation assays, D-dimer, and markers of thrombogenesis (thrombin-antithrombin [TAT]), fibrinolysis, and endothelial activation (intercellular adhesion molecule-1 [ICAM-1]).

RESULTS

D-dimer, TAT, and ICAM-1 concentrations were significantly higher in patients with CKD than HC (P < .01). ROTEM maximum clot firmness was significantly higher in patients than in HC (P < .01). In CKD Stage 5 patients (pre-HD and started HD) adenosine diphosphate and thrombin receptor activating peptide MEA tests were significantly lower than HC indicating platelet aggregation defect (P < .05). Multivariate analysis confirmed the direct effect of estimated glomerular filtration rate (eGFR) in the variance of ROTEM and MEA tests. Endogenous thrombin potential and peak thrombin were not statistically different between groups, but Stage 5 CKD patients had prolonged lag time (7.91 vs. 6.33, P < .001) and time to thrombin peak (10.8 vs. 9.5, P < .05) compared to HC.

CONCLUSIONS

Patients with CKD exhibit features of concomitant hypercoagulability measured by ROTEM and platelet dysfunction measured with MEA. eGFR was an independent determinant of platelet dysfunction and hypercoagulability.

Do all cardiac surgery patients benefit from antifibrinolytic therapy?

BACKGROUND

In trauma patients, the recognition of fibrinolysis phenotypes has led to a re-evaluation of the risks and benefits of antifibrinolytic therapy (AF). Many cardiac patients also receive AF, but the distribution of fibrinolytic phenotypes in that population is unknown. The purpose of this hypothesis-generating study was to fill that gap.

METHODS

Seventy-eight cardiac surgery patients were retrospectively reviewed. Phenotypes were defined as hypofibrinolytic (LY30 <0.8%), physiologic (0.8%-3.0%), and hyperfibrinolytic (>3%) based on thromboelastogram.

RESULTS

The population was 65 ± 10-years old, 74% male, average body mass index of 29 ± 5 kg/m² . Fibrinolytic phenotypes were distributed as physiologic = 45% (35 of 78), hypo = 32% (25 of 78), and hyper = 23% (18 of 78). There was no obvious effect of age, gender, race, or ethnicity on this distribution; 47% received AF. For AF versus no AF, the time with chest tube was longer (4 [1] vs. 3 [1] days, p = .037), and all-cause morbidity was more prevalent (51% vs. 25%, p = .017). However, when these two groups were further stratified by phenotypes, there were within-group differences in the percentage of patients with congestive heart failure (p = .022), valve disease (p = .024), on-pump surgery (p < .0001), estimated blood loss during surgery (p = .015), transfusion requirement (p = .015), and chest tube output (p = .008), which highlight other factors along with AF that might have affected all-cause morbidity.

CONCLUSION

This is the first description of the prevalence of three different fibrinolytic phenotypes and their potential influence on cardiac surgery patients. The use of AF was associated with increased morbidity, but because of the small sample size and treatment allocation bias, additional confirmatory studies are necessary. We hope these present findings open the dialog on whether it is safe to administer AFs to cardiac surgery patients who are normo- or hypofibrinolytic.

Rotational thromboelastometry (ROTEM) profiling of COVID-19 patients

We evaluated coagulation abnormalities via traditional tests and rotational thromboelastometry (ROTEM) in a group of 94 patients with confirmed SARS-CoV-2 infection and different severity of pneumonia (34 moderate, 25 severe, 35 critical) with the hypothesis that ROTEM parameters differed by coronavirus disease 2019 (COVID-19) severity. Shorter than normal clotting time (CT) and higher than normal maximum clot firmness (MCF) in extrinsic rotational thromboelastometry (EXTEM) and fibrinogen rotational thromboelastometry (FIBTEM), shorter than normal EXTEM clot formation time (CFT), and higher than normal α-angle were classified as markers of hypercoagulable state. Increment in the number of patients with ≥2 hypercoagulable parameters, higher EXTEM (P = .0001), FIBTEM MCF (P = .0001) and maximum lysis decrement (P = .002) with increment in disease severity was observed (P = .0001). Significant positive correlations between IL6 and CT EXTEM (P = .003), MCF EXTEM (P = .033), MCF FIBTEM (P = .01), and negative with ML EXTEM (P = .006) were seen. Our findings based on analysis of different disease severity groups confirmed that a hypercoagulable ROTEM pattern characterized by clot formation acceleration, high clot strength, and reduced fibrinolysis was more frequent in advanced disease groups and patients with high IL6. These results supported the need for different thromboprophylaxis approaches for different severity groups.

Analysis of the hemostatic therapy in liver transplantation guided by rotational thromboelastometry or conventional laboratory tests

BACKGROUND

Coagulopathy is quite common in chronic liver disease patients undergoing orthotopic liver transplantation (OLT). Diagnosis of intraoperative bleeding disorders is based on conventional laboratory tests (CLTs), and thus, the patients are frequently exposed to unnecessary transfusions of blood products. The present study aimed to analyze the intraoperative administration of blood products in patients undergoing OLT, using rotational thromboelastometry (ROTEM) or CLTs.

PATIENTS AND METHODS

A cohort comprising 153 patients undergoing OLT, of whom 82 were evaluated with ROTEM and 71 by CLTs. Both groups were analyzed intraoperatively: the transfusion of blood products.

RESULTS

The incidence of patients transfused with cryoprecipitate (CRYO) and/or fibrinogen concentrate (54.9 vs. 19.7%; P < 0.001) and prothrombin complex concentrate (PCC) (32.9 vs. 9.9%; P = 0.008) increased significantly in the ROTEM group than in CLT group, respectively. The amount of transfused patient with CRYO (7.6 vs. 1.2; P < 0.001), fibrinogen concentrate (0.8 vs. 0.2; P = 0.004) and PCC (1.4 vs. 0.2; P = 0.002) increased significantly in the ROTEM group than in the CLT group, respectively. In the analysis of fresh-frozen plasma (FFP), the incidence of transfused patients was significantly higher in the CLT group than in the ROTEM group (46.5 vs. 30.5%; P = 0.047, respectively), with a moderate correlation with red blood cells transfusion (r = 0.67, P < 0.001). The incidence of patients receiving antifibrinolytics was significantly higher in the CLT group than in the ROTEM group (85.9 vs. 47.6%; P < 0.001, respectively).

CONCLUSION

Transfusion protocol-based thromboelastometry was able to guide administration of hemostatic factors and reduced administration of FFP and antifibrinolytics.

The role of ROTEM variables based on clot elasticity and platelet component in predicting bleeding risk in thrombocytopenic critically ill neonates

BACKGROUND

Our aim was to investigate the role of thromboelastometry (ROTEM) parameters, including maximum clot elasticity (MCE) and platelet component (PLTEM MCE and PLTEM MCF), in early prediction of bleeding events in thrombocytopenic critically ill neonates.

MATERIAL AND METHODS

This single-center, prospective cohort study included 110 consecutive thrombocytopenic neonates with sepsis, suspected sepsis, or hypoxia. On the first day of disease onset, ROTEM EXTEM and FIBTEM assays were performed and the neonatal bleeding assessment tool was used for the evaluation of bleeding events.

RESULTS

Most EXTEM and FIBTEM ROTEM parameters significantly differed between neonates with (n = 77) and without bleeding events (n = 33). Neonates with bleeding events had significantly lower PLTEM MCE and PLTEM MCF values compared to those without bleeding events (P < .001). Platelet count was found to be strongly positively correlated with EXTEM A5 (Spearman's rho = 0.61, P < .001) and A10 (rho = 0.64, P < .001). EXTEM A10 demonstrated the best prognostic performance (AUC = 0.853) with an optimal cutoff value (≤37 mm) (sensitivity = 91%, specificity = 76%) for prediction of bleeding events in thrombocytopenic neonates.

CONCLUSIONS

EXTEM A5 and EXTEM A10 were found to be strong predictors of hemorrhage, compared to most ROTEM variables quantifying clot elasticity and platelet component in thrombocytopenic critically ill neonates.

Association between intraoperative rotational thromboelastometry or conventional coagulation tests and bleeding in liver transplantation: an observational exploratory study

INTRODUCTION

Liver transplantation is associated with major blood loss and transfusions. Our objective was to evaluate the association between coagulation results (rotational thromboelastometry (ROTEM) and conventional coagulation tests) and intraoperative bleeding or perioperative red blood cell (RBC) transfusions in liver transplantation.

METHODS

We measured ROTEM values and conventional coagulation tests at the beginning of surgery, after graft reperfusion and at the end of surgery. We did bivariate correlation and multivariable regression analyses to explore the association between test results and either intraoperative bleeding or perioperative RBC transfusions.

RESULTS

We enrolled 75 consecutive patients. Median [Q1-Q3] intraoperative blood loss was 1400 mL [675-2300] and 59% of patients did not receive any RBC transfusion either intraoperatively or postoperatively. In multivariable analyses, FIBTEM maximal clot firmness (MCF) measured at the beginning of surgery was associated with lower intraoperative blood loss (ß = -106 mL for each mm; 95% CI, -203 to -9 mL). Both a higher haemoglobin concentration (multiplicative factor = 0.89 for each g/L; 95% CI, 0.84 to 0.95) and FIBTEM MCF measured at the end of surgery (multiplicative factor = 0.68 for each mm; 95% CI, 0.48 to 0.95) were associated with fewer postoperative RBC transfusions.

CONCLUSION

FIBTEM MCF was strongly associated with intraoperative blood loss and postoperative transfusions while other coagulation results were not. This study might inform future clinical trials on ROTEM-based interventions in liver transplantation.

STUDY REGISTRATION

Clinical Trials.gov: NCT02356068.

Comparison of Coagulation Conditions in Patients With Liver Cirrhosis Due to Primary Sclerosing Cholangitis and Nonbiliary Causes of Cirrhosis Before Orthotopic Liver Transplant

OBJECTIVES

Orthotopic liver transplant can be accompanied by an obscure bleeding pattern in patients with severe hepatic malfunction. In the present study, coagulation conditions of patients with cirrhosis of the liver due to primary sclerosing cholangitis and nonbiliary causes of cirrhosis were compared using rotational thromboelastometry assays obtained before orthotopic liver transplant.

MATERIALS AND METHODS

This case control study analyzed patients who were candidates for orthotopic liver transplant from 2010 to 2016. Eighty patients with cirrhosis of the liver (40 patients with primary sclerosing cholangitis and 40 with nonbiliary causes of cirrhosis) were randomly selected and enrolled into the study. Patients received rotational thromboelastometry assays under anesthesia just before the start of the operation, and results were compared between the 2 patient groups.

RESULTS

Of 80 patients, 52 were men and 28 were women. In the assays, we found that maximum amplitudes in 10 and in 20 minutes and maximum clot firmness parameters were higher in patients with primary sclerosing cholangitis. The alpha angle and clot formation time were different in the intrinsic and extrinsic assay panels. In the intrinsic assay, we found clotting time to be shorter (P < .05). The average of all parameters in all 3 assays (intrinsic, extrinsic, and fibrinogen contribution) was lower in patients with nonbiliary causes of cirrhosis than in those with primary sclerosing cholangitis.

CONCLUSIONS

In contrast with previous studies that found that patients with primary sclerosing cholangitis are hypercoagulable, our study observed that they have normal coagulable results. Furthermore, we found that, although mean coagulation indexes in patients with primary sclerosing cholangitis were within normal ranges, in patients with nonbiliary causes of cirrhosis, these indexes were generally lower.

Correlation between thromboelastography and rotational thromboelastometry values in adult liver transplant recipients

Background and Aims:

Viscoelastic haemostatic assays (VHA) namely Thromboelastogram (TEG) and Rotational thromboelastometry (ROTEM) are used for global assessment of coagulopathy and guiding transfusion during living donor liver transplant (LDLT).We conducted a study to compare the interchangeability of the values obtained from these devices in patients with End stage liver disease (ESLD) undergoing LDLT.

Methods:

In 76 patients undergoing LDLT, ROTEM and TEG were performed and assessed for interchangeability using Spearman Correlation. The direction and strength of correlation between equivalent parameters was calculated using Inter Class Correlation (ICC) and Bland Altman analysis.

Results:

The correlation ρ between CT (clotting time) of ROTEM and R of TEG was 0.16 (P = 0.19).The ICC was 0.15, with 95% confidence interval (CI) of -0.38-0.48 (P = 0.25).The ρ of CFT (ROTEM) with K (TEG) was 0.425 (P=<0.001). The ICC was0.49 with 95% CI of 0.17-0.69, P = 0.003.Alpha of ROTEM correlated with Angle of TEG with ρ of 0.475 (P=<0.001). The ICC was 0.61, with 95% CI of 0.36-0.76, P=<0.001.Maximum Clot firmness (MCF) correlated with maximum amplitude (MA) with ρ=0.76 (P=<0.001).The ICC was 0.86, with 95% CI of 0.77-0.92, P=<0.001. Lysis index (L30) of ROTEM correlated clot lysis (CL30) of TEG with ρ of 0.16 (P = 0.18).However, the ICC was 0.45, with 95% CI of 0.11-0.66, P = 0.08. The correlation between CT of ROTEM and R of TEG as well as L30 of ROTEM and CL30 of TEG was not significant.The strongest correlation was found between MCF and MA (P < 0.001). However the MCF/MA showed an agreement of only 86% (ICC = 0.86).

Conclusion:

Values from ROTEM and TEG were not found to be interchangeable.

A prospective study on the correlation between thromboelastometry and standard laboratory tests - influence of type of surgery and perioperative sampling times

This prospective study aimed at investigating the influence of surgery type and perioperative sampling times on the correlations between rotational thromboelastometry (ROTEM) parameters and standard laboratory coagulation tests assessing comparable coagulation phases. Patients undergoing glioblastoma multiforme resection (GBR group, n = 60) or laparoscopic colon cancer resection (CCR group, n = 40) were prospectively included. Blood samples for ROTEM and laboratory assessments were consecutively drawn within 24-hours prior to surgery (baseline), and at 2, 24 and 48-hours after surgery. Correlations between perioperative ExTEM clotting-time (CT-exTEM) and prothrombin time (PT), and between FibTEM maximum clot firmness (MCF-fibTEM) with and plasma fibrinogen (pFB) concentration (Clauss method), were evaluated using the Spearman's rho test. The efficiency of recommended cut-offs of CT-exTEM (>75 s) and MCF-fibTEM (<10 mm) for predicting a prolonged PT (>15 s) or a low pFB (<2 g/L), respectively, was assessed using Receiver-Operator Characteristic curves. Correlations between CT-exTEM and PT were weak in GBR (rho = 0.25 [0.12-0.38], p < .01), and very weak in CCR (rho = 0.06 [-0.12-0.27]). Those between MCF-fibTEM and pFB, were strong in both GBR (rho = 0.69 [0.61-0.76], p < .01) and CCR (rho = 0.70 [0.60-0.78], p < .01). These correlations remained largely unchanged over the studied perioperative period in both groups. Recommended CT-exTEM and MCF-fibTEM cut-offs had poor sensitivity for predicting a prolonged PT (17% [8-31]) or a low pFB (46% [32-62]), without group-related differences. Neither the type of surgery nor the perioperative sampling times had a significant influence on the correlations between ROTEM parameters and standard laboratory tests. ClinicalTrials.gov ID: NCT02652897.

Predictive value of thromboelastography parameters combined with antithrombin III and D-Dimer in patients with recurrent spontaneous abortion

PROBLEM

To investigate the value of thromboelastography (TEG) combined with antithrombin III (AT-III) and D-Dimer in predicting the occurrence of recurrent spontaneous abortion (RSA).

METHOD OF STUDY

One hundred and five RSA patients and 40 fertile women were enrolled. The subjects were subjected into four groups: group 1 (40 fertile women), group 2 (58 women with 2 abortions), group 3 (30 women with 3 abortions), and group 4 (17 women with four abortions). TEG was conducted on all subjects. Clotting time, reaction time, angle degree, coagulation index, and maximum amplitude were measured. The levels AT-III, D-Dimer, platelet counts, and fibrinogen concentration were determined. The ROC curve analysis was done using MedCalc software to analyse the diagnosis accuracy of the parameters of interest and the combined approach.

RESULTS

The AT-III level in all group 4 was significantly lower than in fertile women. The D-Dimer concentration, platelet count, and MA in patients with four prior abortions were significantly higher than the other three groups. CI and fibrinogen concentration in patients with four prior pregnancy losses were significantly higher than group 1. The ROC curves suggested that combined use of CI, MA, AT-III, and D-Dimer was with the highest accuracy 92.8%, thus predicting the most accurate diagnosis for RSA.

CONCLUSION

Recurrent spontaneous abortion is associated with abnormal coagulation and anticoagulation. TEG combined with detection of AT-III and D-Dimer levels can distinguish patient with RSA from those with normal fertility and highly possibly predict the occurrence of RSA.

Safety of coagulation factor concentrates guided by ROTEM™-analyses in liver transplantation: results from 372 procedures

Background

Most centres use fresh frozen plasma (FFP) based protocols to prevent or treat haemostatic disturbances during liver transplantation. In the present study, we used a rotational thrombelastometry (ROTEM™, TEM, Munich, Germany) guided haemostasis management with fibrinogen concentrates, prothrombin complex concentrates (PCC), platelet concentrates and tranexamic acid without FFP usage and determined the effect on 30 day mortality.

Methods

Retrospective data analysis with 372 consecutive adult liver transplant patients performed between 2007 and 2011.

Results

Thrombelastometry guided coagulation management resulted in a transfusion rate for fibrinogen concentrates in 50.2%, PCC in 18.8%, platelet concentrates in 21.2%, tranexamic acid in 4.5%, and red blood cell concentrates in 59.4%. 30 day mortality for the whole cohort was 14.2%. The univariate analyses indicated that nonsurvivors received significantly more fibrinogen concentrates, PCC, red blood cell concentrates, platelet concentrates, and infusion volume, and had a higher MELD score. However, association with mortality was weak as evidenced by receiver operating characteristic curve analyses. Further univariate analyses demonstrated, that up to 8 g of fibrinogen did not increase mortality compared to patients not receiving the coagulation factor. Multivariate analysis demonstrated that platelet concentrates (p = 0.0002, OR 1.87 per unit), infused volume (p = 0.0004, OR = 1.13 per litre), and MELD score (p = 0.024; OR 1.039) are independent predictors for mortality. Fibrinogen concentrates, PCC, and red blood cell concentrates were ruled out as independent risk factors.

Conclusions

ROTEM™ guided substitution with fibrinogen concentrates and PCC does not negatively affect mortality after liver transplantation, while the well-known deleterious effect associated with platelet concentrates was confirmed.

Point-of-care haemostasis monitoring during liver transplantation is cost effective

Background Optimal haemostasis management in orthotropic liver transplant (OLT) could reduce blood loss and transfusion volume, improve patient outcomes and reduce cost. Methods We performed a study including 336 OLTs to evaluate the clinical and cost effectiveness of a new point-of-care (POC)-based haemostatic management approach in OLT patients. Results In terms of health benefit we found that the new approach showed a significant reduction in transfusion requirements (red blood cell transfusion units were reduced from 5.3±4.6 to 2.8±2.9 [p<0.001], free frozen plasma from 3.1±3.3 to 0.4±1.0 [p<0.001] and platelets from 2.9±3.9 to 0.4±0.9 [p<0.001], transfusion avoidance, 9.7% vs. 29.1% [p<0.001] and massive transfusion, 14.5% vs. 3.8% [p=0.001]); we also found a significant improvement in patient outcomes, such, reoperation for bleeding or acute-kidney-failure (8.3% vs. 2.4%, p=0.015; 33.6% vs. 5.4%, p<0.001), with a significant reduction in the length of the hospital total stay (40.6±13.8 days vs. 38.2±14.4 days, p=0.001). The lowest cost incurred was observed with the new approach (€73,038.80 vs. €158,912.90) with significant patient saving associated to transfusion avoidance (€1278.36), ICU-stay (€3037.26), total-stay (€3800.76) and reoperation for bleeding (€80,899.64). Conclusions POC haemostatic monitoring during OLT is cost effective.

Correlation of early ROTEM parameters with conventional coagulation tests in patients with chronic liver disease undergoing liver transplant

Background and Aims:

Viscoelastic tests such as rotational thromboelastometry (ROTEM) provide a quick and holistic assessment of coagulation status to guide transfusion during liver transplant (LT). Conventional coagulation tests (CCTs) measure single parameters in isolation, and also the results are delayed hampering management of patients during surgery. We evaluated the correlation of early ROTEM-derived parameters with CCTs and also assessed the ability of ROTEM-derived parameters to predict thrombocytopaenia and hypofibrinogenaemia during LT in patients with end-stage liver disease (ESLD).

Methods:

This retrospective study was carried out in 100 patients with decompensated ESLD undergoing LT. Correlation between CCTs and ROTEM parameters was analyzed. Receiver operating characteristic curves with area under the curve were used to determine the cut-off values of A5 andA10 on EXTEM and FIBTEM.

Results:

The values of A5_EXTEM and A10_EXTEM highly correlated with fibrinogen levels and platelet count, whereas A5_FIBTEM and A10_FIBTEM correlated well with fibrinogen levels. A5_EXTEM<21 mm and A10_EXTEM<28 mm correlated with a platelet count <75,000 mm⁻³, whereas A5_EXTEM<18 mm and A10_EXTEM<25 mm correlated with a platelet count <50,000 mm⁻³. Fibrinogen levels <100 mg/dL better correlated with A5_FIBTEM<5 mm, A10_FIBTEM<6 mm, A5_EXTEM<21 mm and A10_EXTEM<30 mm.

Conclusion:

Early ROTEM parameters A5 and A10 of both EXTEM and FIBTEM had an excellent correlation with thrombocytopaenia and hypofibrinogenaemia and may potentially guide early transfusion of relevant blood products during LT.

Thromboelastography-Guided Therapy of Hemorrhagic Complications after Craniopharyngioma Resection: Case-Based Update

PURPOSE

Thromboelastography (TEG) is a point-of-care test that evaluates the entire hemostatic process. The use of TEG is expanding in multiple pediatric surgical disciplines. However, there is very little literature regarding its application in pediatric neurosurgical patients.

METHODS

The authors provide a case-based update and literature review regarding potential applications of TEG to pediatric neurosurgical patients.

RESULTS

The authors describe a 12-year-old female who experienced a number of complications after a craniopharyngioma resection. The patient suffered multiple new intraventricular hemorrhages with removal of external ventricular drains. Standard coagulopathy tests did not reveal any abnormalities. However, an abnormal TEG value suggested primary hyperfibrinolysis, which led to a change in medical management. The patient did not suffer any further bleeding episodes after the change in treatment.

CONCLUSIONS

The authors discuss a case where TEG influenced patient management and identified a problem despite normal values of standard laboratory tests. Neurosurgeons should be aware of the potential benefits for TEG testing in pediatric patients.

Association between viscoelastic tests-guided therapy with synthetic factor concentrates and allogenic blood transfusion in liver transplantation: a before-after study

Background

Perioperative bleeding and transfusion are important causes of morbidity and mortality in patients undergoing liver transplantation. The aim of this study is to assess whether viscoelastic tests-guided therapy with the use of synthetic factor concentrates impact transfusion rates of hemocomponents in adult patients undergoing liver transplantation.

Methods

This is an interventional before-after comparative study. Patients undergoing liver transplantation before the implementation of a protocol using thromboelastometry and synthetic factor concentrates were compared to patients after the implementation. Primary outcome was transfusion of any hemocomponents. Secondary outcomes included: transfusion of red blood cells (RBC), fresh frozen plasma (FFP), cryoprecipitate or platelets, clinical complications, length of stay and in-hospital mortality.

Results

A total of 183 patients were included in the control and 54 in the intervention phase. After propensity score matching, the proportion of patients receiving any transfusion of hemocomponents was lower in the intervention phase (37.0 vs 58.4%; OR, 0.42; 95% CI, 0.20–0.87; p = 0.019). Patients in the intervention phase received less RBC (30.2 vs 52.5%; OR, 0.21; 95% CI, 0.08–0.56; p = 0.002) and FFP (5.7 vs 27.3%; OR, 0.11; 95% CI, 0.03–0.43; p = 0.002). There was no difference regarding transfusion of cryoprecipitate and platelets, complications related to the procedure, hospital length of stay and mortality.

Conclusions

Use of a viscoelastic test-guided transfusion algorithm with the use of synthetic factor concentrates reduces the transfusion rates of allogenic blood in patients submitted to liver transplantation.

Trial registration

This trial was registered retrospectively on November 15th, 2018 – clinicaltrials.gov – Identifier: NCT03756948.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0664-8) contains supplementary material, which is available to authorized users.

Correlation Between ROTEM FIBTEM Maximum Clot Firmness and Fibrinogen Levels in Pediatric Cardiac Surgery Patients

This study evaluated whether rotational thromboelastometry (ROTEM; Tem International GmbH, Munich, Germany) FIBTEM maximum clot firmness (MCF) can be used to predict plasma fibrinogen level in pediatric patients undergoing cardiac surgery. Linear regression was conducted to predict plasma fibrinogen level using FIBTEM MCF (0.05 level of significance). Scatter plot with the regression line for the model fit was created. Fifty charts were retrospectively reviewed, and 87 independent measurements of FIBTEM MCF paired with plasma fibrinogen levels were identified for analysis. Linear regression analysis suggested a significant positive linear relationship (P < .0001) between plasma fibrinogen levels and MCF. Both MCF intercept and slope were significantly correlated with fibrinogen level (P < .0001). The estimated regression equation (predicted fibrinogen = 78.6 + 12.4 × MCF) indicates that a 1-mm increase in MCF raises plasma fibrinogen level by an average of 12.4 mg/dL. The statistically significant positive linear relationship observed between MCF and fibrinogen levels (P < .001) suggests that MCF can be used as a surrogate for fibrinogen level. This relationship is of clinical relevance in the calculation of patient-specific dosing of fibrinogen supplementation in this setting.

Thromboelastography and Thromboelastometry in Assessment of Fibrinogen Deficiency and Prediction for Transfusion Requirement: A Descriptive Review

Fibrinogen is crucial for the formation of blood clot and clinical outcomes in major bleeding. Both Thromboelastography (TEG) and Rotational Thromboelastometry (ROTEM) have been increasingly used to diagnose fibrinogen deficiency and guide fibrinogen transfusion in trauma and surgical bleeding patients. We conducted a comprehensive and comparative review on the technologies and clinical applications of two typical functional fibrinogen assays using TEG (FF TEG) and ROTEM (FIBTEM) for assessment of fibrinogen level and deficiency, and prediction of transfusion requirement. Clot strength and firmness of FF TEG and ROTEM FIBTEM were the most used parameters, and their associations with fibrinogen levels as measured by Clauss method ranged from 0 to 0.9 for FF TEG and 0.27 to 0.94 for FIBTEM. A comparison of the interchangeability and clinical performance of the functional fibrinogen assays using the two systems showed that the results were correlated, but are not interchangeable between the two systems. It appears that ROTEM FIBTEM showed better associations with the Clauss method and more clinical use for monitoring fibrinogen deficiency and predicting transfusion requirements including fibrinogen replacement than FF TEG. TEG and ROTEM functional fibrinogen tests play important roles in the diagnosis of fibrinogen-related coagulopathy and guidance of transfusion requirements. Despite the fact that high-quality evidence is still needed, the two systems are likely to remain popular for the hemostatic management of bleeding patients.

The velocity curve of the clotting waveform of rotational thromboelastometry predicts bleeding after cardiac surgery but conventional rotational thromboelastometric parameters do not

BACKGROUND

Early detection of a risk of postoperative bleeding is essential in cardiac surgery patients. The aim of the present study was to evaluate the utility of the first derivative curve (the V-curve) of the clotting waveform of rotational thromboelastometry (ROTEM) in terms of predicting bleeding after cardiac surgery.

METHODS

We retrospectively analysed 534 cardiac surgery patients. We used the chest tube output during the stay in the intensive care unit to divide patients into a higher blood loss group (HBL group; the fourth quartile) and a lower blood loss group (LBL group; the lower quartiles). We performed multivariable logistic regression using the V-curve parameters and potential confounders including conventional ROTEM parameters.

RESULTS

In the multivariable model, the adjusted odds ratios for HBL of patients with a lower maximum clotting velocity (MaxVel ≤9 mm*100 s-1) as revealed by extrinsically activated ROTEM (EXTEM), and the area under the velocity curve (AUC ≤988 mm*100) of the fibrin-based extrinsically activated ROTEM (FIBTEM), both measured at skin closure in the end of surgery, were 1.78 (95% CI 1.03 to 3.07) and 2.14 (95% CI 1.20 to 3.82), respectively. However, conventional ROTEM parameters were not included in the final model. Additionally, lower EXTEM MaxVel and FIBTEM AUC values were associated with the need for a higher transfusion volume, longer postoperative intensive care unit and hospital stays, and more frequent re-exploration to control bleeding.

CONCLUSIONS

The ROTEM V-curve parameters can predict postoperative bleeding and clinical outcomes after cardiac surgery.

Lysis Timer: a new sensitive tool to diagnose hyperfibrinolysis in liver transplantation

Aims

Diagnosis of hyperfibrinolysis in orthotopic liver transplantation (OLT) remains challenging. Euglobulin clot lysis time (ECLT) is not adapted to clinical situations. ROTEM is specific but seldom sensitive to hyperfibrinolysis. The Lysis Timer assesses ‘Global Fibrinolytic Capacity’ in citrated plasma (GFC/LT). GFC/LT associates reagents for in vitro triggering of the clot (thrombin and calcium) and its lysis (tissue-plasminogenactivator (t-PA)), turbidity signal acquisition by the Lysis Timer, and dedicated software converting the digital signal into an optical curve. A visual check of the curves was systematic to ascertain the lysis time values calculated by the software. The primary aim of this prospective observational study was to evaluate the ability of GFC/LT to recognise hyperfibrinolysis during OLT. The secondary aim was to compare its results with ROTEM maximum lysis (EXTEM ML) and with standard laboratory tests.

Methods

Thirty consecutive adult patients undergoing OLT were included (NCT03012633). Standard laboratory tests, ROTEM, GFC/LT, ECLT and fibrinolysis parameters were assayed at five sample times.

Results

GFC/LT was correlated with ECLT, plasmin activator inhibitor 1 antigen and activity and t-PA activity (r=0.490, 0.681, 0.643 and –0.359, respectively). Hyperfibrinolysis was defined as ECLT ≤60 min. Receiver operating characteristic curve analysis showed that GFC/LT with a threshold of 31 min detected hyperfibrinolysis with a sensitivity of 0.88 (95% CI 0.73 to 0.96), a specificity of 0.68 (95% CI 0.56 to 0.78) and an area under the curve (AUC) of 0.85 (95% CI 0.74 to 0.94). EXTEM ML >12% did not detect hyperfibrinolysis (sensitivity 0.38 (95% CI 0.24 to 0.55), specificity 0.95 (95% CI 0.86 to 0.99) and AUC 0.60 (95% CI 0.46 to 0.75)).

Conclusions

GFC/LT recognised hyperfibrinolysis during OLT with a significant agreement with the other tests of fibrinolysis.

Trial registration number

NCT03012633.

Viscoelastic Testing in Liver Disease

Long thought to be hypocoagulable, new evidence suggests cirrhosis patients have "rebalanced" coagulation in the setting of decreased synthesis of both pro- and anti-coagulant factors. Traditional testing like PT/INR reflects only the decreased synthesis of pro-coagulant factors and thus does not correspond to bleeding or clotting risk in this population. In this review, we discuss the use of viscoelastic testing (VET), an assay of global hemostasis in cirrhosis patients. We describe the technique and interpretation of commercially available VET and assess the application of VET in both transplant and non-transplant cirrhosis populations. VET largely correlates well with traditional testing including platelet count and fibrinogen level, however, is potentially less accurate in patients with low fibrinogen levels. VET may be useful in identifying patients at higher risk of hypercoagulable complications post-transplant and reflects changes in hemostasis in decompensated patients. While VET has been associated with decreased transfusión support in multiple studies, the lack of bleeding in patients who avoided prophylactic transfusion suggests a "rescue" rather than prophylactic approach to transfusion may be ideal and further studies with a "rescue" arm are needed. Additional prospective studies of VET should include clinically relevant endpoints of bleeding and thrombosis.

Antifibrinolytic Therapy and Perioperative Considerations

Fibrinolysis is a physiologic component of hemostasis that functions to limit clot formation. However, after trauma or surgery, excessive fibrinolysis may contribute to coagulopathy, bleeding, and inflammatory responses. Antifibrinolytic agents are increasingly used to reduce bleeding, allogeneic blood administration, and adverse clinical outcomes. Tranexamic acid is the agent most extensively studied and used in most countries. This review will explore the role of fibrinolysis as a pathologic mechanism, review the different pharmacologic agents used to inhibit fibrinolysis, and focus on the role of tranexamic acid as a therapeutic agent to reduce bleeding in patients after surgery and trauma.

Position of the French Working Group on Perioperative Haemostasis (GIHP) on viscoelastic tests: What role for which indication in bleeding situations?

PURPOSE

Viscoelastic tests (VETs), thromboelastography (TEG^®) and thromboelastometry (ROTEM^®) are global tests of coagulation performed on whole blood. They evaluate the mechanical strength of a clot as it builds and develops after coagulation itself. The time required to obtain haemostasis results remains a major problem for clinicians dealing with bleeding, although some teams have developed a rapid laboratory response strategy. Indeed, the value of rapid point-of-care diagnostic devices such as VETs has increased over the years. However, VETs are not standardised and there are few recommendations from the learned societies regarding their use. In 2014, the recommendations of the International Society of Thrombosis and Haemostasis (ISTH) only concerned haemophilia. The French Working Group on Perioperative haemostasis (GIHP) therefore proposes to summarise knowledge on the clinical use of these techniques in the setting of emergency and perioperative medicine.

METHODS

A review of the literature.

PRINCIPAL FINDINGS

The role of the VETs seems established in the management of severe trauma and in cardiac surgery, both adult and paediatric. In other situations, their role remains to be defined: hepatic transplantation, postpartum haemorrhage, and non-cardiac surgery. They must be part of the global management of haemostasis based on algorithms defined in each centre and for each population of patients. Their position at the bedside or in the laboratory is a matter of discussion between clinicians and biologists.

CONCLUSION

VETs must be included in algorithms. In consultation with the biology laboratory, these devices should be situated according to the way each centre functions.

Effects of Tranexamic Acid Based on its Population Pharmacokinetics in Pediatric Patients Undergoing Distraction Osteogenesis for Craniosynostosis: Rotational Thromboelastometry (ROTEMTM) Analysis

Background: Distraction osteogenesis for craniosynostosis is associated with significant hemorrhage. Additionally, patients usually require several transfusions. Tranexamic acid (TXA) is effective for reducing blood loss and the need for transfusions during surgeries. However, the significance of TXA infusion has not been thoroughly described yet. Methods: Forty-eight children undergoing distraction osteogenesis for craniosynostosis were administered intraoperative TXA infusion (loading dose of 10 mg/kg for 15 min, followed by continuous infusion at 5 mg/kg/h throughout surgery; n = 23) or normal saline (control, n = 25). Rotational thromboelastometry (ROTEM^TM) was conducted to monitor changes in coagulation perioperatively. Results: Blood loss during surgery was significantly lower in the TXA-treated group than it was in the control group (81 vs. 116 mL/kg, P = 0.003). Furthermore, significantly fewer transfusions of red blood cells and fresh frozen plasma were required in the TXA group. In the control group, clotting time during the postoperative period was longer than it was during the preoperative period. Similarly, clot strength was weaker during the postoperative period. D-dimer levels dramatically increased in the control group compared with the TXA group after surgery. The duration of mechanical ventilation and the number of postoperative respiratory-related complications were significantly greater in the control group than they were in the TXA group. Conclusions: TXA infusion based on population pharmacokinetic analysis is effective in reducing blood loss and the need for transfusions during the surgical treatment of craniosynostosis. It can also prevent the increase in D-dimer levels without affecting systemic hemostasis.

Viscoelastic Monitoring to Guide Hemostatic Resuscitation in Liver Transplantation Surgery

Coagulopathic bleeding must be anticipated during liver transplantation (LT) surgery. Patients with end-stage liver disease (ESLD) often present with disease-related hematologic disturbances, including the loss of hepatic procoagulant and anticoagulant clotting factors and thrombocytopenia. Transplantation surgery itself presents additional hemostatic changes, including hyperfibrinolysis. Viscoelastic monitoring (VEM) is often used to provide targeted, personalized hemostatic therapies for complex bleeding states including cardiac surgery and major trauma. The use in these coagulopathic conditions led to its application to LT, although the mechanisms of coagulopathy in these patients are quite different. While VEM is often used during transplant surgeries in Europe and North America, evidence supporting its use is limited to a few small clinical studies. The theoretical and clinical applications of the standard and specialized VEM assays are discussed in the setting of LT and ESLD.

Coagulation Management During Liver Transplantation: Use of Fibrinogen Concentrate, Recombinant Activated Factor VII, Prothrombin Complex Concentrate, and Antifibrinolytics

Coagulation management, and transfusion practice in liver transplantation (LT) have been evolving in the recent years due to better understanding of coagulation abnormalities in end-stage liver disease, and clinical management of LT patients. Avoidance of allogeneic blood components is feasible in some patients, but multi-modal coagulation therapies may be necessary in others who develop complex coagulopathy due to hemorrhage, hemodilution, hypothermia, and acid-base disturbances. Transfusions of plasma and cryoprecipitate remain to be the mainstay therapy for procoagulant factor replacement during LT. Clinical efficacy and safety of these products are limited by logistic issues (eg, thawing), and mostly noninfectious complications. Considering potential alternatives to conventional transfusion is thus important to improve hemostatic resuscitation in complex LT cases. The present review is mainly focused on procoagulant properties of plasma and platelet transfusion, and currently available plasma-derived and recombinant factor concentrates, and antifibrinolytic agents in LT patients. The role of viscoelastic coagulation tests to guide specific component therapies will be also discussed.

Rotational Thromboelastometry or Conventional Coagulation Tests in Liver Transplantation: Comparing Blood Loss, Transfusions, and Cost

INTRODUCTION

Orthotopic liver transplantation (OLT) can be associated with significant bleeding requiring multiple blood product transfusions. Rotational thromboelastometry (ROTEM) is a point-of-care device that has been used to monitor coagulation during OLT. Whether it reduces blood loss/transfusions during OLT remains controversial.

MATERIALS AND METHODS

We aim to compare ROTEM with conventional coagulation tests (aPTT, PT, INR, platelet count, fibrinogen) to guide transfusion of platelets, cryoprecipitate, and fresh frozen plasma (FFP) during OLT over 3 years. Thirty-four patients who had transfusions guided by ROTEM were compared to 34 controls who received transfusions guided by conventional coagulation tests (CCT). Intraoperative blood loss, type/ amount of blood products transfused, and direct costs were compared between the two groups.

RESULTS

The ROTEM group had significantly less intra-operative blood loss (2.0 vs. 3.0 L, p = 0.04) and fresh frozen plasma (FFP) transfusion (4 units vs. 6.5 units, p = 0.015) compared to the CCT group (2.0L vs. 3.0L, p = 0.04). However, total number of patients transfused cryoprecipitate was increased in ROTEM (n = 25;73%) as compared to CCT (n = 19; 56%), p = 0.033. The direct cost of blood products plus testing was reduced in the ROTEM group ($113,142.89 vs. $127,814.77).

CONCLUSION

In conclusion implementation of a ROTEM-guided transfusion algorithm resulted in a reduction in intra-operative blood loss, FFP transfusion and a decrease in direct cost during OLT. ROTEM is a useful and safe point of care device in OLT setting.

Transfusion Medicine and Coagulation Management in Organ Transplantation

Organ transplantation recipients present unusual challenges with regard to blood transfusion. Although this patient population requires a larger proportion of blood product resources, liberal transfusion of allogeneic blood products can lead to a plethora of complications. Recent trends suggest that efforts to minimize bleeding, conserve products, and target transfusion to specific deficits and needs are increasingly becoming the standard practice; these must all occur with optimization of graft function and preservation in mind. With newer monitoring modalities and factor concentrates, the approach toward transfusion and bleeding in organ transplantation has rapidly improved in recent years.

Thromboelastometry and Thrombelastography Analysis under Normal Physiological Conditions - Systematic Review

BACKGROUND

Studies investigating thromboelastometry or thrombelastography analyses in a physiological context are scattered and not easy to access.

OBJECTIVE

To systematically retrieve and describe published reports studying healthy subjects and targeting at the correlation of ROTEM® and TEG® measurements with conventional parameters of hemostasis.

METHODS

Systematic Review: Papers were searched in Medline, Scopus and the Science Citation Index database. Reference lists of included studies and of reviews were screened. To be included papers had to report ROTEM or TEG data on healthy subjects. Two reviewers screened papers for inclusion, read full texts of potentially relevant papers, and extracted data of included papers.

RESULTS

Searches identified 1,721 records of which 1,713 were either excluded immediately or after reading the full text. The remaining 8 studies enrolled 632 subjects. The association of conventional parameters of hemostasis with ROTEM and with TEG was investigated in one and two studies, respectively. Overall correlation was limited and ranged from 0.0 to 0.40 (total thrombus generation vs. fibrinogen; clotting time INTEM vs. activated partial thromboplastin time).

CONCLUSIONS

Studies assessing the relationship between thromboelastometry or thromboelastography analyses and conventional parameters of hemostasis in healthy subjects remains scarce, and correlations are limited. Further research is needed to understand the physiology of thromboelastometry and thromboelastography parameters.

Fibrinogen in traumatic haemorrhage: A narrative review

Haemorrhage in the setting of severe trauma is associated with significant morbidity and mortality. There is increasing awareness of the important role fibrinogen plays in traumatic haemorrhage. Fibrinogen levels fall precipitously in severe trauma and the resultant hypofibrinogenaemia is associated with poor outcomes. Hence, it has been postulated that early fibrinogen replacement in severe traumatic haemorrhage may improve outcomes, although, to date there is a paucity of high quality evidence to support this hypothesis. In addition there is controversy regarding the optimal method for fibrinogen supplementation. We review the current evidence regarding the role of fibrinogen in trauma, the rationale behind fibrinogen supplementation and discuss current research.

The thromboelastometric discrepancy between septic and trauma induced disseminated intravascular coagulation diagnosed by the scoring system from the Japanese association for acute medicine

The aim of this study is to evaluate the hematological differences between septic and traumatic disseminated intravascular coagulation (DIC) using the rotational thromboelastometry (ROTEM).This retrospective study includes all sepsis or severe trauma patients transported to our emergency department who underwent ROTEM from 2013 to 2014. All patients were divided into 2 groups based on the presence of DIC diagnosed by the Japanese Association for Acute Medicine (JAAM) DIC score. We statistically analyzed the demographics, clinical characteristics, laboratory data, ROTEM findings (EXTEM and FIBTEM), and outcome.Fifty-seven patients (30 sepsis and 27 severe trauma) were included in primary analysis. Sepsis cases were significantly older and had higher systemic inflammatory response syndrome (SIRS) scores, whereas there were no significant differences in other parameters including Acute Physiology and Chronic Health Evaluation (APACHE) II score, sequential organ failure assessment (SOFA) score. Twenty-six patients (14 sepsis and 12 severe trauma) were diagnosed with DIC. The Septic DIC (S-DIC) group was significantly older and had higher DIC scores than the traumatic DIC (T-DIC) group. Hematologic examination revealed significantly higher CRP, fibrinogen, lower FDP, DD, and higher FDP/DD ratio were found in the S-DIC group in comparison with the T-DIC group. ROTEM findings showed that the A10, A20, and MCF in the FIBTEM test were significantly higher in the S-DIC group. However, no statistical differences were confirmed in the LI30, LI45, and ML in EXTEM test.The plasma fibrinogen level and fibrinogen based clot firmness in whole-blood test revealed statistical significance between septic and traumatic DIC patients.

The utility of thromboelastography in inherited and acquired bleeding disorders

Thromboelastography (TEG) was first described by Hartert in 1948, and was designed to monitor viscoelastic clot strength in whole blood in real time. The current TEG method and Rotational Thromboelastometry (ROTEM) were subsequently developed from the original principles. Both of the modern methods provide data by measuring changes in the viscoelastic strength of a small sample of clotting blood in response to a constant rotational force. The important advantage of these techniques is to visually observe and quantify blood coagulation including the propagation, stabilization and dissolution phases of clot formation under low shear conditions. Analysis of the results provides detailed kinetic data on fibrin generation, clot strength and fibrinolysis. These TEG/ROTEM analyses therefore enable evaluation of global clotting function and the monitoring of haemostatic treatment in various clinical situations, not only in patients with genetic bleeding disorders, such as haemophilia, but also in patients undergoing cardiac surgery, liver transplantation or suffering from traumatic injury. Some evidence suggests that haemostatic management using TEG/ROTEM leads to a reduction in total transfusions of whole blood or clotting factors. Wider clinical application of this technology seems likely.

Ex vivo evaluation of 4 different viscoelastic assays for detecting moderate to severe coagulopathy during liver transplantation

Prolonged prothrombin time (PT) and its ratio are routinely used for the assessment of candidates for liver transplantation (LT), but intraoperative coagulation management of transfusion is hindered by its long turnaround time. Abnormal reaction time (R time) on thromboelastography (TEG) or clotting time (CT) of rotational thromboelastometry (ROTEM) are presumably an alternative, but there is a paucity of clinical data on abnormal R time/CT values compared to PT during LT. After receiving institutional review board approval and informed consent, we obtained blood samples from 36 LT patients for international normalized ratio (INR), factor (F) X level, and viscoelastic tests (EXTEM/INTEM and kaolin/rapid TEG) at baseline and 30 minutes after graft reperfusion. Receiver operating characteristic (ROC) curves were calculated for INR > 1.5 and viscoelastic R time/CT thresholds to assess the ability to diagnose FX deficiency at the moderate (<50%) or severe (<35%) level. The FX deficiency data were calculated using cutoff values of INR (>1.5) and abnormal R time/CT for TEG and ROTEM. Tissue factor (TF)-activated INR and EXTEM-CT performed well in diagnosing FX below 50%, but rapid TEG with combined TF and kaolin activators failed. Improved performance of INTEM-CT in diagnosing FX below 35% underlies multifactorial deficiency involving both intrinsic and common pathways. In conclusion, the differences among different viscoelastic tests and clinical situations should be carefully considered when they are used to guide transfusion during LT.