Does thromboelastography predict postoperative thromboembolic events? A systematic review of the literature

Standard tests of haemostasis do not predict elevated thromboelastographic maximum amplitude, an index of hypercoagulability, in sick dogs

OBJECTIVES

To compare standard tests of haemostasis in hypercoagulable and normocoagulable sick dogs as identified by thromboelastography.

MATERIALS AND METHODS

We compared prothrombin time, activated partial thromboplastin time, D-dimers, packed red blood cell volume and platelet counts in client-owned sick dogs with hypercoagulable (n = 36) and normocoagulable (n = 35) states as identified by thromboelastography maximum amplitude above or within the established reference interval, respectively.

RESULTS

Seventy-one dogs were included. Thirty-six dogs were hypercoagulable and 35 were normocoagulable on thromboelastography. Using multivariable linear models, prothrombin time, activated partial thromboplastin time and D-dimers were not associated with hypercoagulability. Platelet counts and packed red blood cell volume were significantly associated with hypercoagulability.

CLINICAL SIGNIFICANCE

Prothrombin time, activated partial thromboplastin time and D-dimers were not useful in the identification of hypercoagulability in dogs as defined by thromboelastography.

Changes in Coagulation in Cancer Patients Undergoing Cytoreductive Surgery with Hyperthermic Intraperitoneal Chemotherapy Treatment (HIPEC)-A Systematic Review

Venous thromboembolism and postoperative bleeding are complications of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC). The aim of this systematic review was to summarize current knowledge on the effect of cytoreductive surgery with HIPEC on coagulation and fibrinolysis within 10 days after surgery. Studies were identified in PubMed, Embase, and Web of Science on December 12, 2022. Data on biomarkers of coagulation and fibrinolysis measured preoperatively up to the 10th postoperative day were extracted. Among 15 included studies, 13 studies reported markers of primary hemostasis. Eleven studies found reduced platelet count following cytoreductive surgery with HIPEC and two studies reported reduced platelet function. Twelve studies reported impaired secondary hemostasis until postoperative day 10 indicated by prolonged international normalized ratio, prothrombin time, and activated partial thromboplastin time. Fibrinogen was decreased in three studies from preoperative to postoperative day 3 switching to increased levels until postoperative day 10. In accordance, three studies found reduced maximum amplitude and maximum clot firmness by thromboelastography/thromboelastometry (ROTEM/TEG) on the first postoperative day indicating impaired clot strength. Four studies demonstrated increased d-dimer, factor (F) VIII, and thrombin generation during the 10 postoperative days. Four studies investigated fibrinolysis by ROTEM/TEG and plasminogen activator inhibitor-1 (PAI-1) after cytoreductive surgery with HIPEC reporting contradictive results. In conclusion, a decrease in platelet count and subtle changes in secondary hemostasis were found following cytoreductive surgery with HIPEC. Data on the effect of cytoreductive surgery with HIPEC on fibrinolysis are sparse and this needs to be further investigated.

Thromboelastographic results and hypercoagulability in dogs with surgically treated hepatocellular adenoma and carcinoma: A Veterinary Society of Surgical Oncology prospective study

BACKGROUND

The most common haemostatic abnormality in dogs with cancer is hypercoagulability. A transient hypercoagulability has been documented in people with hepatocellular carcinoma (HCC) that resolves within weeks following hepatic tumour resection.

OBJECTIVE

The objective was to compare the haemostatic status of dogs with liver tumours and healthy control dogs, by comparing coagulation and thromboelastography (TEG) measurements at three time points.

METHODS

Liver tumour and healthy control dogs receiving surgery for liver lobectomy and ovariohysterectomy, respectively, were prospectively enrolled. All dogs had blood collected at three time points: pre-operative, 24 h post-operative and ~2 weeks post-operative. Haematological and haemostatic values were compared across time points in each group using repeated measures ANOVA tests.

RESULTS

Ten and eight dogs were enrolled for the liver and control groups, respectively. Platelet count was significantly higher in the liver group than the control group at all time points, but within the normal range (pre-operative: 438.7 vs. 300.9 × 109 /L, p = .0078; 24 h post-operative: 416.2 vs. 283.9 × 109 /L, p = .0123; 10-14 days post-operative: 524.6 vs. 317.3 × 109 /L, p = .0072). The measure of the overall coagulant state (G-value) was significantly increased for the liver group compared to the control group at all time points (pre-operative: 15.6 vs. 8.6 d/sc, p = .0003; 24 h post-operative: 18.3 vs. 11.2 d/sc, p = .039; 10-14 days post-operative: 15.1 vs. 9.6 d/sc, p = .015).

CONCLUSION

The liver group was hypercoagulable based on elevated G-values at all time points compared to the control group. This hypercoagulability was attributed to the effect of hepatic tumours alone, and not secondary to surgery and anaesthesia.

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.

Comparison of a viscoelastic point-of-care coagulation monitor with thromboelastography in sick dogs with hemostatic abnormalities

BACKGROUND

Viscoelastic coagulation monitor (VCM-Vet) is a point-of-care device that has been used to characterize hemostatic abnormalities in sick pets but has not been validated in veterinary patients.

OBJECTIVES

We aimed to compare VCM-Vet and thromboelastography (TEG) in sick dogs with suspected disorders of hemostasis.

METHODS

Duplicate VCM-Vet tests using untreated native blood performed concurrently on two VCM-Vet machines, and simultaneous TEG tests were performed (one citrated native (CN), and one activated with tissue factor (TF) at a 1:3600 dilution). Each VCM-Vet result was compared with both TF-activated and CN TEG.

RESULTS

Fifty-three dogs were enrolled. Eleven cases displayed apparent hyperfibrinolysis. Spearman correlation coefficients for individual VCM-Vet devices and CN and TF TEG were obtained between R and CT values and ranged from 0.21 to 0.27, CFT and K (r = 0.60-0.67), angles (r = 0.51-0.62), and MCF and MA (r = 0.85-0.87). Comparison of the two VCM-Vet devices displayed positive correlations for all clot formation parameters with Lin's concordance correlation coefficients of 0.75-0.95. Variable lysis parameter agreement existed between the VCM-Vet devices and VCM-Vet and TEG. When samples were classified as hypercoagulable or coagulopathic, VCM-Vet had a low positive predictive value (17-33%) for the detection of hypercoagulable states and a moderate negative predictive value (64-74%) for the detection of coagulopathy as defined by TEG.

CONCLUSIONS

VCM-Vet and TEG had variable correlations in clot formation values and a strong correlation for final clot strength. More information is needed to make conclusions about the lysis parameters. Artifact in the fibrinolysis portion of the test can confound the interpretation of VCM-Vet results.

The Influence of Environmental Hypoxia on Hemostasis—A Systematic Review

Humans have been ascending to high altitudes for centuries, with a growing number of professional- and leisure-related sojourns occurring in this millennium. A multitude of scientific reports on hemostatic disorders at high altitude suggest that hypoxia is an independent risk factor. However, no systematic analysis of the influence of environmental hypoxia on coagulation, fibrinolysis and platelet function has been performed. To fill this gap, we performed a systematic literature review, including only the data of healthy persons obtained during altitude exposure (<60 days). The results were stratified by the degree of hypoxia and sub-categorized into active and passive ascents and sojourns. Twenty-one studies including 501 participants were included in the final analysis. Since only one study provided relevant data, no conclusions regarding moderate altitudes (1,500–2,500 m) could be drawn. At high altitude (2,500–5,400 m), only small pathophysiological changes were seen, with a possible impact of increasing exercise loads. Elevated thrombin generation seems to be balanced by decreased platelet activation. Viscoelastic methods do not support increased thrombogenicity, with fibrinolysis being unaffected by high altitude. At extreme altitude (5,400–8,850 m), the limited data showed activation of coagulation in parallel with stimulation of fibrinolysis. Furthermore, multiple confounding variables at altitude, like training status, exercise load, fluid status and mental stress, prevent definitive conclusions being drawn on the impact of hypoxia on hemostasis. Thus, we cannot support the hypothesis that hypoxia triggers hypercoagulability and increases the risk of thromboembolic disorders, at least in healthy sojourners.

A Systematic Review of Thromboelastography Utilization in Vascular and Endovascular Surgery

OBJECTIVE

Thromboelastography (TEG) is diagnostic modality that analyzes real-time blood coagulation parameters. Clinically, TEG primarily allows for directed blood component resuscitation among patients with acute blood loss and coagulopathy. The utilization of TEG has been widely adopted in among other surgical specialties; however, its use in vascular surgery is less prominent. We aimed to provide an up-to-date review of TEG utilization in vascular and endovascular surgery.

METHODS

Using PRISMA guidelines, a literature review with the Medical Subject Headings (MeSH) terms "TEG and arterial events", "TEG and vascular surgery", "TEG and vascular", "TEG and endovascular surgery", "TEG and endovascular", "TEG and peripheral artery disease", "TEG and prediction of arterial events", "TEG and prediction of complications ", "TEG and prediction of thrombosis", "TEG and prediction of amputation", and "TEG and amputation" was performed in Cochrane and PubMed databases to identify all peer-reviewed studies of TEG utilization in vascular surgery, written between 2000-2021 in the English language. The free text and MeSH subheadings search terms included diagnosis, complications, physiopathology, surgery, mortality, and therapy to further restrict the articles. Studies were excluded if they were not in humans or pertaining to vascular or endovascular surgery. Additionally, case reports and studies with limited information regarding TEG utilization were excluded. Each study was independently reviewed by two researchers to assess for eligibility.

RESULTS

Of the 262 studies identified through the MeSH strategy, 15 studies met inclusion criteria and were reviewed and summarized. Literature on TEG utilization in vascular surgery spanned cerebrovascular disease (n=3), peripheral arterial disease (n=3), arteriovenous malformations (n=1), venous thromboembolic events (n=7), and perioperative bleeding and transfusion (n=1). In cerebrovascular disease, TEG may predict the presence and stability of carotid plaques, analyze platelet function before carotid stenting, and compare efficacy of antiplatelet therapy after stent deployment. In peripheral arterial disease, TEG has been used to predict disease severity and analyze the impact of contrast on coagulation parameters. In venous disease, TEG may predict hypercoagulability and thromboembolic events among various patient populations. Finally, TEG can be utilized in the postoperative setting to predict hemorrhage and transfusion requirements.

CONCLUSIONS

This systematic review provides an up-to-date summarization of TEG utilization in multiple facets of vascular and endovascular surgery.

Thrombin Generation Assay and Hemostatic Profile for Elucidating Hypercoagulability in Endogenous Canine Hyperadrenocorticism

Canine hyperadrenocorticism is a common endocrine disorder caused by chronic secretion of glucocorticoid, often associated with hypercoagulability and secondary thrombosis. The thrombin generation assay (TGA) evaluates hemostasis globally by measuring endogenous thrombin potential. We aimed to determine whether TGA is suitable for assessing hypercoagulability in dogs with endogenous hyperadrenocorticism (HAC), and to correlate TGA with coagulation markers including fibrinogen, antithrombin (AT), D-dimer, prothrombin time (PT) and activated partial thromboplastin time (aPTT), and with routine laboratory tests for elucidating prothrombotic mechanisms and evaluating their utility as hypercoagulability screening tests. Thrombin generation performed with high activator concentration showed significantly higher endogenous thrombin potential (ETP) (P = .0239) and peak thrombin (P = .0281) in Cushing patients. Fibrinogen (P = <.0001) and AT (P = .0444) activities were significantly higher in the HAC group, while those of PT (P = .0046) and aPTT (P = .0002) were lower. Basal cortisol levels correlated positively with fibrinogen (r = 0.4503; P = .0355) and negatively with AT activity (r = -0.4580; P = .0280). Fibrinogen and hematocrit values were inversely correlated (r = -0.4853; P = .0076). Our study confirmed the presence of higher thrombin generation in dogs with HAC. However, TGA performed with lower activator concentrations was unsuitable for detecting hypercoagulability. Higher AT and fibrinogen levels and lower aPTT activity were identified in dogs with HAC relative to controls suggesting a potential role for the combined use of these assays when assessing hypercoagulability in canine hyperadrenocorticism.

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.

The Pathophysiology of Hypercoagulability and Infertility

Alongside an interplay of a multitude of factors, attainment of a favorable pregnancy outcome is predicated on successful implantation, which in itself is a complex process anchored by balanced interchange with the hemostatic system. Among other etiologies, failure of implantation can result in infertility, and lead affected couples to consider assisted reproductive technology (ART) in an effort to fulfill their desire for procreation. Given the critical role of the hemostatic system in the process of implantation, documentation of a hypercoagulable state during controlled ovarian stimulation in the context of in vitro fertilization, as well as the potential association of its derangement in the setting of thrombophilia, with infertility, ART, ovarian hyperstimulation syndrome, and failure of implantation are explored. Additionally, current evidence addressing the relationship between ART and thromboembolism is examined, as is the role of therapy with heparin and aspirin to decrease thrombotic risk and improve ART-related pregnancy outcomes. Evidence-based recommendations from relevant professional societies are summarized.

Intraoperative thromboelastography as a tool to predict postoperative thrombosis during liver transplantation

BACKGROUND

Thromboembolic complications are relatively common causes of increased morbidity and mortality in the perioperative period in liver transplant patients. Early postoperative portal vein thrombosis (PVT, incidence 2%-2.6%) and early hepatic artery thrombosis (HAT, incidence 3%-5%) have a poor prognosis in transplant patients, having impacts on graft and patient survival. In the present study, we attempted to identify the predictive factors of these complications for early detection and therefore monitor more closely the patients most at risk of thrombotic complications.

AIM

To investigate whether intraoperative thromboelastography (TEG) is useful in detecting the risk of early postoperative HAT and PVT in patients undergoing liver transplantation (LT).

METHODS

We retrospectively collected thromboelastographic traces, in addition to known risk factors (cold ischemic time, intraoperative requirement for red blood cells and fresh-frozen plasma transfusion, prolonged operating time), in 27 patients, selected among 530 patients (≥ 18 years old), who underwent their first LT from January 2002 to January 2015 at the Liver University Transplant Center and developed an early PVT or HAT (case group). Analyses of the TEG traces were performed before anesthesia and 120 min after reperfusion. We retrospectively compared these patients with the same number of nonconsecutive control patients who underwent LT in the same study period without developing these complications (1:1 match) (control group). The chosen matching parameters were: Patient graft and donor characteristics [age, sex, body mass index (BMI)], indication for transplantation, procedure details, United Network for Organ Sharing classification, BMI, warm ischemia time (WIT), cold ischemia time (CIT), the volume of blood products transfused, and conventional laboratory coagulation analysis. Normally distributed continuous data are reported as the mean ± SD and compared using one-way Analysis of Variance (ANOVA). Non-normally distributed continuous data are reported as the median (interquartile range) and compared using the Mann-Whitney test. Categorical variables were analyzed with Chi-square tests with Yates correction or Fisher’s exact test depending on best applicability. IBM SPSS Statistics version 24 (SPSS Inc., Chicago, IL, United States) was employed for statistical analysis. Statistical significance was set at P < 0.05.

RESULTS

Postoperative thrombotic events were identified as early if they occurred within 21 d postoperatively. The incidence of early hepatic artery occlusion was 3.02%, whereas the incidence of PVT was 2.07%. A comparison between the case and control groups showed some differences in the duration of surgery, which was longer in the case group (P = 0.032), whereas transfusion of blood products, red blood cells, fresh frozen plasma, and platelets, was similar between the two study groups. Thromboelastographic parameters did not show any statistically significant difference between the two groups, except for the G value measured at basal and 120’ postreperfusion time. It was higher, although within the reference range, in the case group than in the control group (P = 0.001 and P < 0.001, respectively). In addition, clot lysis at 60 min (LY60) measured at 120’ postreperfusion time was lower in the case group than in the control group (P = 0.035). This parameter is representative of a fibrinolysis shutdown (LY60 = 0%-0.80%) in 85% of patients who experienced a thrombotic complication, resulting in a statistical correlation with HAT and PVT.

CONCLUSION

The end of surgery LY60 and G value may identify those recipients at greater risk of developing early HAT or PVT, suggesting that they may benefit from intense surveillance and eventually anticoagulation prophylaxis in order to prevent these serious complications after LT.

Hemostatic changes by thrombopoietin-receptor agonists in immune thrombocytopenia patients

Thrombopoietin receptor agonist (TPO-RA) treatment increases the thrombosis rate in immune thrombocytopenia (ITP). We hypothesize that TPO-RAs influence platelet function, global and secondary hemostasis and/or fibrinolysis. A systematic review was performed. If possible, data were compared between responders (relevant increase in platelet count), and non-responders. Twelve observational studies with 305 patients were included (responders (127/150 (85%))). There were indications that TPO-RA treatment enhanced platelet function, with respect to platelet-monocyte aggregates, soluble P-selectin, GPVI expression, and adhesion under flow. Studies addressing global and secondary hemostasis and fibrinolysis were scarce. Overall, no changes were found during TPO-RA treatment, apart from an accelerated clot formation and conflicting data on levels of plasminogen activator inhibitor (PAI)-1. The parameters that increased have previously been associated with thrombosis in other patient groups, and might contribute to the increased rate of thrombosis observed in TPO-RA-treated ITP patients.

Management of the thrombotic risk associated with COVID-19: guidance for the hemostasis laboratory

Coronavirus disease 2019 (COVID-19) is associated with extreme inflammatory response, disordered hemostasis and high thrombotic risk. A high incidence of thromboembolic events has been reported despite thromboprophylaxis, raising the question of a more effective anticoagulation. First-line hemostasis tests such as activated partial thromboplastin time, prothrombin time, fibrinogen and D-dimers are proposed for assessing thrombotic risk and monitoring hemostasis, but are vulnerable to many drawbacks affecting their reliability and clinical relevance. Specialized hemostasis-related tests (soluble fibrin complexes, tests assessing fibrinolytic capacity, viscoelastic tests, thrombin generation) may have an interest to assess the thrombotic risk associated with COVID-19. Another challenge for the hemostasis laboratory is the monitoring of heparin treatment, especially unfractionated heparin in the setting of an extreme inflammatory response. This review aimed at evaluating the role of hemostasis tests in the management of COVID-19 and discussing their main limitations.

Thromboelastography and rotational thromboelastometry for the surgical intensivist: A narrative review

BACKGROUND

Viscoelastic tests (VETs), specifically thromboelastography (TEG) and rotational thromboelastometry (ROTEM), are gaining popularity in the management of critically ill surgical patients with hemorrhage or thrombosis due to their comprehensive characterization of the coagulation process and point-of-care availability in comparison to conventional coagulation tests (CCTs). We review current evidence for VET use in patients in the surgical intensive care unit (SICU).

METHODS

We searched PUBMED, EMBASE and the Cochrane Library through May 30, 2018 for articles that evaluated the use of VETs in patient populations and clinical scenarios germane to the surgical intensivist. Individual articles were critically evaluated for relevance and appropriate methodology using a structured technique. Information on patient characteristics, timing and methods of CCTs/VETs, and outcomes was collected and summarized in narrative form.

RESULTS

Of 2,589 identified articles, 36 were included. Five (14%) were interventional studies and 31 (86%) were observational. Twenty-five (69%) evaluated TEG, 11 (31%) ROTEM and 18 (50%) CCTs. Investigated outcomes included quantitative blood loss (13 (36%)), blood product transfusion (9 (25%)), thromboembolic events (9 (25%)) and mortality (6 (17%)). We identified 12 clinical scenarios with sufficient available evidence, much of which was of limited quantity and poor methodological quality. Nonetheless, research supports the use of VETs for guiding early blood product administration in severe traumatic hemorrhage and for the prediction of abstract excess bleeding following routine cardiac surgery. In contrast, evidence suggests VET-based heparin dosing strategies for venous thromboembolism prophylaxis are not superior to standard dosing in SICU patients.

CONCLUSION

While VETs have the potential to impact the care of critically ill surgical patients in many ways, current evidence for their use is limited, mainly because of poor methodological quality of most available studies. Further high-quality research, including several ongoing randomized controlled trials, is needed to elucidate the role of TEG/ROTEM in the SICU population.

LEVEL OF EVIDENCE

Systematic review, level IV.

Optimizing Perioperative Blood and Coagulation Management During Cardiac Surgery

Bleeding and transfusion are common in cardiac surgery and associated with poorer outcome. Bleeding is frequently due to coagulopathy caused by the complex interaction between cardiopulmonary bypass, major surgical trauma, anticoagulation management, and perioperative factors. Patient blood management has emerged to improve outcome by the prediction, prevention, monitoring, and treatment of bleeding and transfusion. Each part of this chain has several individual modalities and when combined leads to result in a better outcome. This article reviews the hemostasis disturbances in cardiac surgery with cardiopulmonary bypass and gives an overview of the most important patient blood management strategies.

A preliminary study using rotational thromboelastometry to investigate perioperative coagulation changes and to identify hypercoagulability in obese patients undergoing total hip or knee replacement

Surgery and obesity are known risk factors for thromboembolic events due to the presence of a hypercoagulable state. Rotational thromboelastometry is a viscoelastic assay that can provide a measure of hypercoagulability via a comprehensive assessment of the coagulation process. This prospective study investigates haemostatic changes over time, presence of hypercoagulability and the association between body mass index and thromboelastometry results in patients undergoing major orthopaedic surgery. Fifty adult patients undergoing total hip or knee replacement surgery had serial thromboelastometry measures performed prior to and following surgery, and on postoperative days 1 and 3. A hypercoagulable state, defined by an ExTEM maximum clot firmness G score ≥11 dyne/cm2, was present in 28% of the patients at baseline. The mean ExTEM maximum clot firmness G score increased by an average of three units from 10 (95% confidence interval (CI) 9–11) dyne/cm2 at baseline to 13 (95% CI 13–14) dyne/cm2 on postoperative day 3, with 85% of patients having a G score ≥11 dyne/cm2. A decrease in ExTEM and InTEM clot formation time and an increase in ExTEM, InTEM and FibTEM clot amplitude at 10 minutes, alpha angle and maximum clot firmness were observed by postoperative day 3 ( P <  0.001). There was no significant difference in the mean thromboelastometry values between patients with a body mass index <35 kg/m2or ≥35 kg/m2. Although a modest association between body mass index and the ExTEM maximum clot firmness G score was observed with exploratory data analysis, further study is required in a large cohort to test the effects of confounders, validate these findings, and determine their clinical importance.

Assessment of agreement and interchangeability between the TEG5000 and TEG6S thromboelastography haemostasis analysers: a prospective validation study

Background

TEG6S® and TEG5000® (Haemonetics Corp, USA) are haemostasis analysers that measure viscoelasticity properties of whole blood. Both use different mechanisms to assess similar components of the coagulation process. The aim of this study was to assess agreement and interchangeability between the TEG6S and TEG5000 analysers.

Methods

3.5 mL whole blood was collected from 25 adult patients in a tertiary intensive care unit (ICU). Analysis was performed using TEG6S and TEG5000 haemostatic platforms. Agreement between platforms was measured using Lin’s concordance coefficient (Lin’s CC), further validated using intraclass correlation coefficients and reduced major axis regression (RMAR).

Results

Sixteen (64%) patients were male; mean (range) age: 59yo (23–86). TEG6S and TEG5000 systems were broadly interchangeable. The majority of TEG variables demonstrated almost perfect or substantial agreement and minimal proportional bias (maximum amplitude demonstrated a fixed bias). LY30%, however, demonstrated poor agreement and a proportional bias. Lin’s CC coefficients (95% CI, RMAR slope, intercept) between TEG6S and TEG5000 variables were: R time: 0.78 (0.64–0.92, 0.76, 0.92); K time: 0.82 (0.69–0.94, 1.30, − 0.93); alpha angle: 0.79 (0.64–0.95, 1.04, − 1.43); maximum amplitude (MA): 0.90 (0.83–0.96, 0.99, − 5.0); LY30%: 0.34 (0.1–0.58, 0.43, 0.04).

Conclusions

Adult patients with critical illness demonstrate almost perfect agreement in the R time and MA, substantial agreement in K time and alpha angle, but poor agreement in LY30%, as measured by the TEG6S and TEG5000 analysers. With the exception of LY30%, the TEG6S and TEG5000 platforms appear interchangeable. This has important implications for use in clinical practice and multi-site research programs.

Trial registration

ANZCRT number: 12617000062325, registered 12/Jan17. Retrospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s12871-019-0717-7) contains supplementary material, which is available to authorized users.

Effect of Coagulation Status and Co-Morbidity on Flap Success and Complications in Patients with Reconstructed Free Flap

Objective

Free flap surgeries constitute the basis of reconstruction surgery in patients with major defects. Prediction of complications that cause flap loss in such patients is important in terms of reducing the length of hospital stay and expenses. We aimed to retrospectively investigate the effect of co-morbidities and the coagulation status on flap loss and complications in patients with reconstructed free flap.

Methods

Demographic data, smoking, alcohol habits, co-morbidities, coagulation tests and thromboelastogram results from preoperative, intraoperative and postoperative anaesthesia and surgical records of patients undergoing free flap surgeries between January 2015 and June 2017 were retrospectively screened.

Results

Flap success rate was found to be 96.1% in total 77 patients with free flap. Coagulation related complication rate, such as thrombosis, haematoma and partial necrosis, were 22.1%. There was a significant relationship between age, chronic obstructive pulmonary disease and hypercholesterolaemia and flap loss (p=0.006, p=0.025 ve p=0.025, respectively). Flap complications were more frequent in patients with chronic obstructive pulmonary disease and hypertension. Laboratory test results revealed no statistical correlation between flap complications and flap loss with preoperative and postoperative TEG.

Conclusion

Advanced age, co-morbidities such as hypertension and chronic obstructive pulmonary disease are associated with complications and flap loss in free flap surgery. However, there were no clinically significant association of complications and flap loss with laboratory tests showing coagulation. We believe that standardised protocols should be established in terms of preparation, intraoperative management and postoperative follow-ups because the time between taking the coagulation tests and postoperative anticoagulant administration should be standardised in such surgeries.

Effect of Liver Disease Etiology on ROTEM Profiles in Patients Undergoing Liver Transplantation

BACKGROUND

Coagulation abnormalities in liver transplant patients are complex and may be related to the underlying liver disease. We evaluated the effects of disease etiology on whole-blood rotational thromboelastometry (ROTEM; Pentapharm GmbH, Munich, Germany) profile and association with thrombotic complications following liver transplantation.

METHODS

Analysis of perioperative data from patients undergoing liver transplantation between January 1, 2012 and December 31, 2016. Patients were grouped based on the biology of their underlying liver disease: hepatocellular carcinoma (HCC), biliary etiology, and non-biliary etiology. The primary outcome was the EXTEM A10 value of the pre-incision ROTEM. Secondary outcomes included associations between EXTEM A10 value and incidence of postoperative thrombotic complications.

RESULTS

Three hundred fifty patients met the eligibility criteria: 60 had biliary etiologies, 203 had non-biliary etiologies, and 87 had HCC. EXTEM A10 values were significantly higher in patients with biliary etiologies than those with non-biliary etiologies (mean difference, 13.8; 95% CI: 10.1 to 17.5; P = .001) and those with HCC (mean difference, 10.4; 95% CI: 6.2 to 14.7; P = .001). Patients with non-biliary etiologies had slightly higher values than those with HCC (mean difference, -3.3; 95% CI: -6.6 to -0.1; P = .04). Higher values for biliary etiologies remained after adjusting for liver disease severity, platelet count, and fibrinogen level. There was no significant difference in EXTEM A10 values between patients who suffered thrombotic complications and those who did not (mean difference: 4.3, 95% CI: -1.3 to 9.9, P = .13).

CONCLUSION

Patients with biliary diseases demonstrated higher EXTEM A10 values compared to those with non-biliary diseases or HCC. This was not fully explained by differences in disease severity, platelet count, or fibrinogen level. Pre-incision EXTEM A10 values do not predict incidence of postoperative thrombotic complications.

Patients With Budd-Chiari Syndrome Have Variable Coagulation Status on Thromboelastography at Diagnosis

BACKGROUND & AIMS

Budd-Chiari Syndrome (BCS) is considered a thrombophilic state, and most patients with BCS have thrombophilic disorder. Liver dysfunction-related coagulopathy makes coagulation function unpredictable in BCS. Thromboelastography (TEG) assesses the dynamics, strength, and stability of clot formation. We conducted a pilot study using TEG to evaluate coagulation status in patients with BCS.

METHODS

Fifty-one patients with newly diagnosed BCS (age 32.3 [10.7] years; 23 men) underwent TEG (TEG®5000 Hemostasis Analyzer®, USA), and its components were analyzed and correlated with clinical profile and thrombophilic disorders. Patients who had received anticoagulation, antiplatelet drugs, or radiological intervention were excluded.

RESULTS

Twenty-nine patients had normal TEG, 11 had procoagulant TEG, and 11 had hypocoagulant TEG. Among patients with hypocoagulant TEG, Coagulation Index (CI) was < -3 in 11 patients, R was >8 min in 6 patients, K was >3 min in 9 patients, alpha <55 in 9 patients, and MA <51 in 7 patients; among those with hypercoagulant TEG, CI was >3 in 3 patients, R < 2 min in 2 patients, K <1 min in 2 patients, alpha >78 in none, and MA >69 mm in 7 patients. TEG findings were similar in patients with and without thrombophilic disorder. The mean platelet count (1.75, 2.22, and 1.79 × 10⁵/mm³; P = 0.13) and international normalized ratio (1.27, 1.34, and 1.28, P = 0.69) were similar in those with procoagulant, normal, and hypocoagulant TEG. Two patients in Rotterdam class-III had abnormal LY30. Other clinical parameters did not correlate with TEG findings.

CONCLUSION

Patients with BCS are heterogeneous with respect to coagulation status, with one-fifth of patients are hypocoagulant on TEG. Patients with advanced disease may have accelerated fibrinolysis.

Thrombin generation in patients with severe thermal injury

BACKGROUND

Severe burns can induce a hypercoagulable state which is not depicted in conventional coagulation assays. The thrombin generation assay allows global assessment of coagulation and can identify hypercoagulability. We report changes in thrombin generation in patients after severe burn injury.

METHODS

We measured TGA, rotational thrombelastometry and conventional assays in 20 consecutive patients with a total body surface area burned of >20% over a 2-week period: the day after burn trauma (A), the morning after surgical excision of burn wounds (B) and on post-admission days 7 (C) and 14 (D).

RESULTS

Thrombin generation assay showed a procoagulatory state: there was an increase in the velocity of thrombin generation (increase in time to peak of +13%, increase in velocity index of +22%), and peak amount of thrombin (+25%) between days A and B. All parameters reached their highest levels on day C and returned towards normal on day D. Rotational thrombelastometry showed a hypercoagulable state with an increase in clot firmness and alpha angle. Conventional coagulation tests remained within reference values.

CONCLUSIONS

In the first two weeks following burn, both the thrombin generation assay and rotational thrombelastometry show a hypercoagulable state, while conventional coagulation tests remain normal.

Thromboelastometry and Platelet Function during Acclimatization to High Altitude

Interaction between hypoxia and coagulation is important given the increased risk of thrombotic diseases in chronically hypoxic patients who reside at sea level and in residents at high altitude. Hypoxia alters the proteome of platelets favouring a prothrombotic phenotype, but studies of activation and consumption of specific coagulation factors in hypoxic humans have yielded conflicting results. We tested blood from 63 healthy lowland volunteers acclimatizing to high altitude (5,200 m) using thromboelastometry and assays of platelet function to examine the effects of hypoxia on haemostasis. Using data from two separate cohorts of patients following identical ascent profiles, we detected a significant delay in clot formation, but increased clot strength by day 7 at 5,200 m. The latter finding may be accounted for by the significant rise in platelet count and fibrinogen concentration that occurred during acclimatization. Platelet function assays revealed evidence of platelet hyper-reactivity, with shortened PFA-100 closure times and increased platelet aggregation in response to adenosine diphosphate. Post-expedition results were consistent with the normalization of coagulation following descent to sea level. These robust findings indicate that hypoxia increases platelet reactivity and, with the exception of the paradoxical delay in thromboelastometry clotting time, suggest a prothrombotic phenotype at altitude. Further work to elucidate the mechanism of platelet activation in hypoxia will be important and could impact upon the management of patients with acute or chronic hypoxic respiratory diseases who are at risk of thrombotic events.

The hypercoagulability paradox of chronic kidney disease: The role of fibrinogen

BACKGROUND

Chronic kidney disease (CKD) patients have increased rates of bleeding as well as thrombosis. Fibrinogen and platelets combine to generate a mature clot, but in CKD platelets are dysfunctional. Therefore, we hypothesize that CKD patients have increased clot strength due to elevated fibrinogen levels.

METHODS

Retrospective review of CKD patients (n = 84) who had rTEG and fibrinogen levels measured. They were compared to healthy controls (n = 134).

RESULTS

CKD patients had statistically significant increases in ACT, angle, MA and decreases in LY30 compared to controls. Fibrinogen levels were increased in CKD patients compared to reference range. Fibrinogen levels had a positive correlation with MA (rho = 0.709, p < 0.0001) in CKD patients.

CONCLUSIONS

Patients with CKD manifest a coagulopathy consisting of delayed clot formation, but increased final clot strength and decreased clot breakdown. Furthermore, the elevated clot strength is mediated by increased fibrinogen levels in CKD patients.

Preoperative Thromboelastography as a Sensitive Tool Predicting Those at Risk of Developing Early Hepatic Artery Thrombosis After Adult Liver Transplantation

BACKGROUND

Whilst causes of hepatic artery thrombosis (HAT) after liver transplantation (LT) are multifactorial, early HAT (E-HAT) remains pertinent complication impacting on graft and patient survival. Currently there is no screening tool that would identify patients with increased risk of developing E-HAT.

METHODS

We analyzed the native procoagulant state of LT recipients, identified through pretransplant thromboelastographic (TEG) data among other known risk factors, to identify risk factors for E-HAT.

RESULTS

The outcomes of 828 adult patients undergoing LT between 2008 and 2013 were analyzed. Overall, 79 (9.5%) patients experienced HAT, E-HAT was diagnosed in 23, and in the remainder this was "late" HAT. The maximum amplitude (MA) on preoperative TEG was significantly higher in patients diagnosed with E-HAT compared with those who did not (71.2 mm vs 57.9 mm; P < 0.0001). Receiver operating characteristic analysis with the cutoff value for MA of 65 mm or greater returned area under the curve of 0.750 (P < 0.001) predicting E-HAT with a sensitivity of 70%. A total of 7% of patients with an MA of 65 mm or greater went on to develop E-HAT (hazard ratio, 5.28; 95% confidence interval, 2.10-12.29; P < 0.001), whereas only 1.2% patients with an MA less than 65 mm experienced E-HAT.

CONCLUSIONS

Preoperative TEG may reliably identify group of recipients at greater risk of developing E-HAT, and intense surveillance and anticoagulation prophylaxis may avoid this serious complication after LT.

Impaired Platelet Aggregation and Rebalanced Hemostasis in Patients with Chronic Hepatitis C Virus Infection

Increased risk of both cardiovascular disease (CVD) and bleeding has been found in patients with chronic hepatitis C (CHC) infection, and a re-balanced hemostasis has been proposed. The aim of this study was to investigate functional whole blood coagulation and platelet function in CHC infection. The prospective study included 82 patients with CHC infection (39 with advanced liver fibrosis and 43 with no or mild liver fibrosis) and 39 healthy controls. A total of 33 patients were treated for CHC infection and achieved sustained virological response (SVR). Baseline and post-treatment blood samples were collected. Hemostasis was assessed by both standard coagulation tests and functional whole blood hemostatic assays (thromboelastograhy (TEG), and platelet aggregation (Multiplate). Patients with CHC and advanced fibrosis had impaired platelet aggregation both compared to patients with no or mild fibrosis and to healthy controls. Patients with CHC and advanced fibrosis also had lower antithrombin, platelet count, and coagulation factors II-VII-X compared to healthy controls. In contrast, TEG did not differ between groups. In treated patients achieving SVR, post-treatment platelet count was higher than pre-treatment counts (p = 0.033) and ADPtest, ASPItest, and RISTOhightest all increased post treatment (all p < 0.05). All Multiplate tests values, however, remained below those in the healthy controls. CHC-infected patients displayed evidence of rebalanced hemostasis with only partly hemostatic normalization in patients achieving SVR. The implications of rebalanced hemostasis and especially the impact on risk of CVD and bleeding warrants further studies.

Monitoring of Hypercoagulability by Thromboelastography in Bariatric Surgery

Background

Obesity is known as a major risk factor for postoperative vein thrombosis. Thromboelastography (TEG) is used to monitor viscoelastic features of blood clots. The aim of this study was to determine hypercoagulable states in patients undergoing bariatric surgery and to assess dynamics of coagulation parameters in the perioperative setting using TEG.

Material/Methods

We included 60 consecutive patients undergoing bariatric surgery. TEG alterations were assessed at 4 time points: at baseline, after the surgery, and on postoperative day 1 (POD1) and 2 (POD2). Hypercoagulable state was defined when patients showed clot strength (G) of ≥11 dynes/cm² or maximum amplitude (MA) ≥68 mm.

Results

Fourteen patients (23.3%) out of 60 showed hypercoagulability prior to surgery on TEG. Fibrinogen levels were significantly higher in the G ≥11 group compared to the G <11 group, at 4.2 and 3.8 g/l, respectively (p=0.02). Seventeen patients (28.3%) had MA ≥68 mm at baseline. Fibrinogen levels increased significantly from 3.90 at baseline to 4.16 g/l in POD2 (p<0.001). There was an increase in mean reaction time from baseline (6.74 s) to POD2 (7.43 s, p=0.022). We found a correlation between baseline fibrinogen levels and MA (R=0.431, p=0.001) or G (R=0.387, p=0.003). ROC curve analysis showed that fibrinogen levels can predict clot strength (G) ≥11 dynes/cm² with AUC=0.680 (p=0.044).

Conclusions

A considerable proportion of patients referred to bariatric surgery show a trend towards hypercoagulability on TEG. This study shows the potential of hypercoagulation monitoring by TEG in the perioperative setting of bariatric surgery.

A New Perspective on the Risk of Hypercoagulopathy in Ovarian Hyperstimulation Syndrome Using Thromboelastography

Thromboelastography (TEG) provides real-time assessment of hemostasis by measuring the viscoelastic properties, coagulation factor, and platelet activity in whole blood samples. In this prospective case-control study, we wanted to investigate whether blood clot formation assessment, using TEG, can identify a hypercoagulable state in women with severe ovarian hyperstimulation syndrome (OHSS). Thirty-six women who were hospitalized with severe OHSS were allocated to the OHSS group and 32 women undergoing controlled ovarian hyperstimulation but who did not develop OHSS were allocated to the control group. The TEG indices were compared between women with severe OHSS and controls. All the coagulation indices assessed by TEG were significantly different in the OHSS group compared to the controls, depicting a hypercoagulable state. Median coagulation index was 3.6 (interquartile range: 2.80-4.15) and 1.45 (interquartile range: 0.20-2.30) in study group and controls, respectively ( P < .001). Our results show that TEG can be used to depict a hypercoagulable state in women with severe OHSS.

Correlation between thromboelastography and traditional coagulation test parameters in hospitalized dogs

A hospital-based, prospective cross-sectional study was used to compare kaolin-activated thromboelastography (TEG) parameters with traditional coagulation tests in 29 hospitalized dogs. Cases were included if the attending clinician requested coagulation testing. Blood was obtained from each dog and coagulation (prothrombin time, partial thromboplastin time, antithrombin activity, d-dimer concentration, and fibrinogen concentration) and TEG analyses were performed. Hematocrit (Hct) was also measured. Traditional coagulation results were evaluated for correlation with those from kaolin-activated TEG. Spearman’s correlation was used to calculate correlation coefficients. Fibrinogen was positively correlated with maximum amplitude (Pearson r=0.72, P<0.001) and global clot strength (Pearson r=0.72, P<0.001). There was no correlation between any of the remaining coagulation variables, TEG parameters, or Hct. Results of kaolin-activated TEG and traditional coagulation tests are not interchangeable means of monitoring coagulation derangements in this intensive care unit patient population. Determination of a true outcome measure is necessary to establish TEG’s clinical relevance to veterinary medicine.

Endogenous Fibrinolysis: An Important Mediator of Thrombus Formation and Cardiovascular Risk

Most acute cardiovascular events are attributable to arterial thrombosis. Plaque rupture or erosion stimulates platelet activation, aggregation, and thrombosis, whilst simultaneously activating enzymatic processes that mediate endogenous fibrinolysis to physiologically maintain vessel patency. Interplay between these pathways determines clinical outcome. If proaggregatory factors predominate, the thrombus may propagate, leading to vessel occlusion. However, if balanced by a healthy fibrinolytic system, thrombosis may not occur or cause lasting occlusion. Despite abundant evidence for the fibrinolytic system regulating thrombosis, it has been overlooked compared with platelet reactivity, partly due to a lack of techniques to measure it. We evaluate evidence for endogenous fibrinolysis in arterial thrombosis and review techniques to assess it, including biomarkers and global assays, such as thromboelastography and the Global Thrombosis Test. Global assays, simultaneously assessing proaggregatory and fibrinolytic pathways, could play a role in risk stratification and in identifying impaired fibrinolysis as a potential target for pharmacological modulation.

Does tramadol affect coagulation status of patients with malignancy?

AIM

The study investigated the direct effects of tramadol on the coagulation status of women with gynecologic malignancies in vitro.

MATERIALS AND METHODS

Citrated whole-blood samples from 21 patients with gynecologic tumors were spiked ex vivo with 2 or 6 μl/ml tramadol. Thrombelastography (TEG) analysis was performed using ROTEM(®) to assess clotting time (CT), clot formation time (CFT) and maximum clot formation (MCF).

RESULTS

In the INTEM assay, CT (P < 0.05) and CFT (P < 0.01) were significantly prolonged with tramadol at a 6 μl/ml concentration compared with baseline. There were no significant differences in MCF values between the baseline and the tramadol-treated samples (P > 0.05). Blood medicated with tramadol (6 μl/ml) clotted slowly (increased CT and CFT).

CONCLUSION

The changes observed by TEG demonstrated that tramadol impairs hemostasis in a concentration-dependent manner in the whole blood of women with gynecologic malignancies in vitro.

Global assays of hemostasis in the diagnostics of hypercoagulation and evaluation of thrombosis risk

Thrombosis is a deadly malfunctioning of the hemostatic system occurring in numerous conditions and states, from surgery and pregnancy to cancer, sepsis and infarction. Despite availability of antithrombotic agents and vast clinical experience justifying their use, thrombosis is still responsible for a lion’s share of mortality and morbidity in the modern world. One of the key reasons behind this is notorious insensitivity of traditional coagulation assays to hypercoagulation and their inability to evaluate thrombotic risks; specific molecular markers are more successful but suffer from numerous disadvantages. A possible solution is proposed by use of global, or integral, assays that aim to mimic and reflect the major physiological aspects of hemostasis process in vitro. Here we review the existing evidence regarding the ability of both established and novel global assays (thrombin generation, thrombelastography, thrombodynamics, flow perfusion chambers) to evaluate thrombotic risk in specific disorders. The biochemical nature of this risk and its detectability by analysis of blood state in principle are also discussed. We conclude that existing global assays have a potential to be an important tool of hypercoagulation diagnostics. However, their lack of standardization currently impedes their application: different assays and different modifications of each assay vary in their sensitivity and specificity for each specific pathology. In addition, it remains to be seen how their sensitivity to hypercoagulation (even when they can reliably detect groups with different risk of thrombosis) can be used for clinical decisions: the risk difference between such groups is statistically significant, but not large.

Rotational thrombelastometry: a step forward to safer patient care?

The study by Hincker and colleagues indicated that the perioperative use of rotational thrombelastometry (ROTEM™) could predict thromboembolic events in 90% of the cases in non-cardiac surgery. Viscoelastic tests (VETs)--ROTEM™ and thrombelastography (TEG™)--are used mainly to predict bleeding complications. Most conventional coagulation tests, like prothrombin time and activated partial thromboplastin time, can identify a disturbance in plasmatic hemostasis. However, the relevance of these assays is limited to the initiation phase of coagulation, whereas VETs are designed to assess the whole clotting kinetics and strength of the whole blood clot and reflect more the interaction between procoagulants, anticoagulants, and platelets. The first reports about VET and hypercoagulable state were published more than 25 years ago. Since then, several studies with different quality and sample size have been published, sometimes with conflicting results. A systematic review about hypercoagulable state and TEG™ indicated that further studies are needed to recommend VETs as a screening tool to predict postoperative thrombosis.

Rotational thromboelastometry predicts thromboembolic complications after major non-cardiac surgery

Introduction

Thromboembolic complications contribute substantially to perioperative morbidity and mortality. Routine laboratory tests do not detect patients with acquired or congenital hypercoagulability who may be at increased risk of perioperative thromboembolism. Rotational thromboelastometry (ROTEM) is a digitized modification of conventional thromboelastography that is stable and technically easy to use. We designed a prospective observational study to evaluate whether preoperative ROTEM can identify patients at increased risk for postoperative thromboembolic complications after major non-cardiac surgery.

Methods

Preoperative ROTEM analysis using extrinsic rotational thromboelastometry (EXTEM), intrinsic rotational thromboelastometry (INTEM), and fibrinogen rotational thromboelastometry (FIBTEM) activators was performed on 313 patients undergoing major non-cardiac surgery. Patients’ medical records were reviewed after discharge for results of standard coagulation studies - partial thromboplastin time (PTT), international normalized ratio (INR), platelet count - and evidence of thromboembolic complications during their hospital stay. A thromboembolic complication was defined as a new arterial or deep venous thrombosis, catheter thrombosis, or pulmonary embolism diagnosed by ultrasound or spiral chest computed tomography.

Results

Ten patients developed postoperative thromboembolic complications, of whom 9 had received standard prophylaxis with subcutaneous enoxaparin or heparin. There was no indication of by PTT, INR, or platelet count. Preoperative EXTEM and INTEM activators that assess fibrin clot formation and platelet interaction indicated that these patients had significantly lower clot formation time (CFT) and significantly higher alpha angle (α) and maximum clot firmness (MCF), compared to patients without thromboembolic complications. There was no significant difference for any parameter using FIBTEM activator, which excludes platelet interaction. Receiver operating characteristic (ROC) curves were constructed for these variables. INTEM clot firmness at 10 min (A10) was the best predictor of thromboembolic complications, with an ROC area under the curve of 0.751.

Conclusions

Our results indicate that preoperative ROTEM assays that include fibrin clot and platelet interaction may detect patients at increased risk for postoperative thromboembolic complications after major non-cardiac surgery. Future studies need to evaluate the clinical utility and cost effectiveness of preoperative ROTEM and better define the association between ROTEM values and specific hypercoagulable conditions.