Use Of Viscoelastic Tests Research Articles

Guidelines for the Management of Adult Acute and Acute-on-Chronic Liver Failure in the ICU: Cardiovascular, Endocrine, Hematologic, Pulmonary and Renal Considerations: Executive Summary.

OBJECTIVES To develop evidence-based recommendations for clinicians caring for adults with acute or acute on chronic liver failure in the ICU. DESIGN The guideline panel comprised 29 members with expertise in aspects of care of the critically ill patient with liver failure and/or methodology. The Society of Critical Care Medicine standard operating procedures manual and conflict-of-interest policy were followed throughout. Teleconferences and electronic-based discussion among the panel, as well as within subgroups, served as an integral part of the guideline development. SETTING The panel was divided into nine subgroups: cardiovascular, hematology, pulmonary, renal, endocrine and nutrition, gastrointestinal, infection, perioperative, and neurology. INTERVENTIONS We developed and selected population, intervention, comparison, and outcomes questions according to importance to patients and practicing clinicians. For each population, intervention, comparison, and outcomes question, we conducted a systematic review aiming to identify the best available evidence, statistically summarized the evidence whenever applicable, and assessed the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation approach. We used the evidence to decision framework to facilitate recommendations formulation as strong or conditional. We followed strict criteria to formulate best practice statements. MEASUREMENTS AND MAIN RESULTS In this article, we report 29 recommendations (from 30 population, intervention, comparison, and outcomes questions) on the management acute or acute on chronic liver failure in the ICU, related to five groups (cardiovascular, hematology, pulmonary, renal, and endocrine). Overall, six were strong recommendations, 19 were conditional recommendations, four were best-practice statements, and in two instances, the panel did not issue a recommendation due to insufficient evidence. CONCLUSIONS Multidisciplinary international experts were able to formulate evidence-based recommendations for the management acute or acute on chronic liver failure in the ICU, acknowledging that most recommendations were based on low-quality indirect evidence.

Commentary on: Comparison of three transfusion protocols prior to central venous catheterization in patients with cirrhosis: A randomized controlled trial

Commentary on: Comparison of three transfusion protocols prior to central venous catheterization in patients with cirrhosis: A randomized controlled trial

Sensitivity of Viscoelastic Tests to Platelet Function.

Viscoelastic tests provide a dynamic assessment of coagulation, by exploring the time to clot formation and the clot strength. Using specific activators or inhibitors, additional factors can be explored, like the fibrinogen contribution to clot strength. Since the early days, various attempts have been done to measure platelet function with viscoelastic test. In general, the difference between the maximum clot strength and the fibrinogen contribution is considered an index of platelet contribution. However, this parameter does not clearly split platelet count from function; additionally, the extensive thrombin generation of standard activated viscoelastic tests activates platelet through the protease activated receptors, bypassing the other pathways. For this reason, standard viscoelastic tests cannot be used to assess platelet reactivity under the effects of aspirin or P2Y12 inhibitors. To overcome this limitation, a specific test was developed (thromboelastography platelet mapping). This test has been compared with the gold standard of light transmission aggregometry and with other point-of-care tests, with conflicting results. In general, the use of viscoelastic tests to assess the effects of antiplatelet agents is still limited. Conversely, platelet contribution to clot strength in the setting of coagulopathic bleeding is considered an important parameter to trigger platelet transfusion or desmopressin.

Is thromboelastography reliable in postpartum coagulopathies? Two case reports and a literature review

Abstract Postpartum hemorrhage (PPH) is an underestimated problem in labor and delivery units and remains a leading cause of maternal morbidity and mortality worldwide. Managing PPH starts with immediate recognition and intervention. Goal-directed massive transfusion protocol can be achieved by properly monitoring the maternal coagulation profile during severe obstetric hemorrhage. Conventional coagulation tests (prothrombin time, activated partial thromboplastin time, international normalized ratio, fibrinogen analysis, platelet count) have long turnaround times (occasionally >60 min and provide little information about the in vivo condition of hemostasis) compared to viscoelastic tests (VETs) (available results within 10–30 min). The outcome in actively hemorrhaging patients can be optimized by VETs, including thromboelastography (TEG), rotational thromboelastometry and Sonoclot, providing more individualized blood component therapy compared to traditional 1:1:1 ‘damage control resuscitation’ ratios of blood transfusion strategy. The main limitations of the efficacy of VETs include, but are not limited to, the lack of validation, not having well-established reference ranges for each patient group, results affected by fluid resuscitation regimes and consistent operator proficiency. Although there is limited data with the use of VETs in obstetric patients, the value of VETs is supported by guidelines with increasing evidence. This article will demonstrate two obstetric cases to evaluate the reliability of the TEG in the management of postpartum coagulopathies. The lesson we took from our two cases is presented.

The Utilization of Viscoelastic Testing to Guide Blood Component Therapy and Adjunctive Hemostatic Therapy for Postpartum Hemorrhage: A Narrative Review

This narrative review discusses the history of the pathophysiologic principles and utilization of point-of-care (POC) viscoelastic tests (VETs) in the definition and treatment of postpartum hemorrhage (PPH). This paper addresses the epidemiology of PPH, describes the hemostatic changes that occur in pregnancy and in PPH, and demonstrates the utilization of viscoelastic testing in the identification and treatment of patients with PPH. Additionally, a description of rotational thromboelastometry (ROTEM) and thromboelastography (TEG), the two most commonly used VETs, is detailed in this paper. VETs have only recently been used to guide blood component therapy (BCT) in trauma in the last decade. The recent increased utilization of VETs to guide BCT in PPH is following a similar trend with a delay of ten years. In a similar fashion to the trauma literature, which expanded greatly within this last decade, the literature concerning the use of VETs in PPH has also increased in the last few years. However, because of differing pathophysiologies associated with the coagulopathy of PPH verses traumatic-induced coagulopathy (TIC), utilization of VETs has been more refined and focused on the VETs’ capacity to determine low fibrinogen and to guide the utilization of blood components and prohemostatic agents. The identification and treatment of PPH depends on clinical parameters, conventional coagulation tests (CCTs) including Clauss fibrinogen, and VETs. Successful treatment of PPH will no doubt include utilization of all three strategies with an increasing utilization of VETs in the future.

Clinical Application of Thromboelastography/Thromboelastometry (TEG/TEM) in the Neonatal Population: A Narrative Review.

Hemostasis is a dynamic age-related process, which gradually evolves from fetal life throughout childhood until adulthood. Although at birth there is a hemostatic deficit of most coagulation factors, studies have shown that this "hemostatic immaturity" is functionally counterbalanced in healthy term or preterm newborns. This delicate hemostatic balance is, however, deranged in sick neonates, resulting in an enhanced risk of hemorrhage and/or thrombosis. In critically ill neonates, conventional coagulation tests do not seem to provide reliable information or indications regarding the functional status of platelets or fibrinolysis. In contrast, viscoelastic tests, namely thromboelastography/thromboelastometry (TEG/TEM) hold promise for rapid assessment of the whole hemostatic potential, allowing immediate intervention should this be required. However, neonatal data are limited due to lack of reference values, especially in premature neonates. In this narrative review, we provide some insights around current knowledge regarding TEG/TEM applications in healthy and sick newborns. Overall, the use of viscoelastic tests in diagnosis and management of coagulation disorders in neonates is definitely worth further exploration. Consideration should be made to include these tests in the routine laboratory investigation of neonates and specific transfusion algorithms should also be developed in order to avoid treatment pitfalls.

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

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). 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. 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. 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. Systematic review, level IV.

Invited Commentary

Bleeding after cardiopulmonary bypass (CPB) is a complicated issue, especially in pediatric patients. Multiple age-related, CPB-related, and surgery-related variables come together to influence the amount of coagulopathy any given child will experience after CPB. Fortunately, with the advent of viscoelastic tests, thromboelastography (TEG) or rotational thromboelastometry (ROTEM), a path to identify and correct the coagulation abnormalities that are likely responsible is clearer now more than ever. These tests, performed on whole blood, allow for rapid assessment of clotting time, thrombocytopenia, hypofibrinogenemia, and fibrinolysis. Furthermore, they offer insight into platelet–fibrin interactions, fibrin polymerization, and possibly even thrombin generation. Studies that incorporate TEG and ROTEM testing into transfusion algorithms are beginning to emerge and report success in reducing allogeneic blood product exposure without an increase in postoperative bleeding [1Romlin B.S. Wahlander H. Berggren H. et al.Intraoperative thromboelastometry is associated with reduced transfusion prevalence in pediatric cardiac surgery.Anesth Analg. 2011; 112: 30-36Crossref PubMed Scopus (102) Google Scholar, 2Nakayama Y. Nakajima Y. Tanaka K.A. et al.Thromboelastometry-guided intraoperative haemostatic management reduces bleeding and red cell transfusion after paediatric cardiac surgery.Br J Anaesth. 2015; 114: 91-102Abstract Full Text Full Text PDF PubMed Scopus (112) Google Scholar, 3Kane L.C. Woodward C.S. Husain S.A. Frei-Jones M.J. Thromboelastography—does it impact blood component transfusion in pediatric heart surgery?.J Surg Res. 2016; 200: 21-27Abstract Full Text Full Text PDF PubMed Scopus (42) Google Scholar]. In this issue of The Annals of Thoracic Surgery, Emani and colleagues report their experience along this path [4Emani S. Sleeper L.A. Faraoni D. et al.Thromboelastography is associated with surrogates for bleeding after pediatric cardiac operations.Ann Thorac Surg. 2018; 106: 799-806Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar]. The authors perform a retrospective study in high-risk pediatric patients undergoing complex cardiac repairs to determine whether abnormal TEG parameters are associated with a surrogate endpoint for early postoperative bleeding. TEGs were obtained immediately after protamine administration (prior to the administration of post-CPB blood products) and upon arrival to the intensive care unit (ICU). To be clear, the TEGs were strictly observational and not clinically used to guide transfusion management. The authors define a composite endpoint for excessive bleeding, extended transfusion (ie, the need for blood products after the initial post-CPB transfusion of platelets), or the need for surgical reexploration. Of the 511 patients, 52% of patients with a maximum amplitude (MA) less than 45 mm reached the composite endpoint versus 31% with a MA greater than 45 mm (p < 0.001). In those patients who had an MA less than 45 mm, platelet transfusion intraoperatively was associated with a significant increase in median [IQR] MA (40.8 mm [37.5, 43] in the operating room versus 63.4 mm [56.2, 69.7] in the ICU; p < 0.001) and a lower incidence of the composite endpoint. Overall, MA less than 45 mm and neonatal age were independently associated with the composite endpoint. There are limitations to this study. The authors do not mention how it was decided to administer other products after the initial transfusion of platelets. Was there a defined process or was it subjectively decided by the anesthesia or surgery or ICU team? In addition, it is well known that neonates and small infants experience a significant dilutional hypofibrinogenemia after CPB, even when fresh frozen plasma is included in the circuit prime [5Hornykewycz S. Odegard K.C. Castro R.A. Zurakowski D. Pigula F. Dinardo J.A. Hemostatic consequences of a non-fresh or reconstituted whole blood small volume cardiopulmonary bypass prime in neonates and infants.Paediatr Anaesth. 2009; 19: 854-861Crossref PubMed Scopus (24) Google Scholar], and these patients often require fibrinogen repletion with cryoprecipitate. According to the authors’ defined composite endpoint, this would be considered “extended transfusion”. Thus, it is likely that the incidence they report for the composite endpoint is inflated. Nevertheless, studies similar to the one conducted by Emani and associates that explore the use of viscoelastic tests to guide transfusion algorithms are greatly needed. Such algorithms will likely vary according to institutions and their differing practices, and may even need to vary according to different target populations. In addition, the use of age-specific reference ranges and functional fibrinogen assays will further enhance our insight into the appropriate therapies. As reflected in the article by Emani and co-workers, we are beginning to make our way along this path. Thromboelastography Is Associated With Surrogates for Bleeding After Pediatric Cardiac OperationsThe Annals of Thoracic SurgeryVol. 106Issue 3PreviewPerioperative bleeding is a common complication in pediatric patients undergoing cardiac operation. Although thromboelastography (TEG) has been used in patients undergoing adult cardiac operation, limited data are available in pediatric patients. We hypothesize that TEG variables may be associated with surrogate end points for postoperative bleeding in pediatric patients undergoing complex cardiac operation. Full-Text PDF

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 transfusion 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.

Use of viscoelastic tests to predict clinical thromboembolic events: A systematic review and meta‐analysis

We aimed to assess whether whole-blood viscoelastic tests are useful to identify patients who are hypercoagulable and at increased risk of thromboembolism. Two investigators independently analyzed studies in the MEDLINE, EMBASE, and Cochrane controlled trial register databases to determine the ability of viscoelastic tests to identify a hypercoagulable state that is predictive of objectively proven thromboembolic events. Forty-one eligible studies, including 10,818 patients, were identified and subject to meta-analysis. The majority of the studies (n=36, 88%) used the maximum clot strength to identify a hypercoagulable state which had a moderate ability to differentiate between patients who developed thromboembolic events and those who did not (area under the summary receiver operating characteristic [sROC] curve=0.70, 95% confidence interval [CI]: 0.65-0.75). The pooled sensitivity, specificity, and diagnostic odds ratio to predict thromboembolism were 56% (95%CI: 44-67), 76% (95%CI: 67-83), and 3.6 (95%CI: 2.6-4.9), respectively. The predictive performance did not vary substantially between patient populations, and publication bias was not observed. Current evidence suggests that whole-blood viscoelastic tests have a moderate ability to identify a variety of patient populations with an increased risk of thromboembolic events and can be considered as a useful adjunct to clinical judgment to stratify a patient's risk of developing thromboembolism.

Decompressive Craniectomy in a Patient with Severe Traumatic Brain Injury during Mild Therapeutic Hypothermia

Mild Therapeutic Hypothermia (MTH) and decompressive craniectomy are therapeutic measures used for the treatment of intracranial hypertension (ICHT) refractory to medical treatment and cerebrospinal fluid drainage. One of the side effects of MTH is the increased risk of coagulopathy, thus the performance of neurosurgical procedures in these cases is very controversial.We present the case of a patient with traumatic brain injury and ICHT refractory to medical treatment, in which moderate therapeutic hypothermia was initiated. After a transient improvement, the patient presented ICHT again, requiring a decompressive craniotomy while keeping the patient in moderate hypothermia. Due to the history of traumatic brain injury and the use of MTH, we decided on the use of viscoelastic tests as goal-directed therapy to assess haemostasis prior to surgery.

Viscoelastic testing for hepatic surgery: a systematic review with meta-analysis-a protocol.

BackgroundViscoelastic tests, including thromboelastography (TEG) and rotational thromboelastometry (ROTEM), provide a global assessment of haemostatic function at the point of care. The use of a TEG or ROTEM system to guide blood product administration has been shown in some surgical settings to reduce transfusion requirements. The aim of this review is to evaluate all published evidence regarding viscoelastic testing in the setting of hepatic surgery.MethodsWe will search MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials databases to identify randomised controlled trials examining the use of viscoelastic testing for hepatic surgery. Two reviewers will independently screen titles and abstracts of studies identified and will independently extract data. Any disagreements will be resolved by discussion with a third reviewer. A meta-analysis will be conducted if feasible.DiscussionViscoelastic devices such as TEG and ROTEM are increasingly available to clinicians as a bedside test. Patients undergoing hepatic surgery have a significant risk of blood loss and coagulopathy requiring transfusion. Theoretical benefits of use of a TEG or ROTEM system in the hepatic surgical setting include a rationalisation of blood products, a reduction in transfusion-related side effects, an improvement in patient outcomes including mortality, and a reduction in cost. This systematic review will summarise the current evidence regarding the use of viscoelastic testing for hepatic surgery.Systematic review registrationPROSPERO CRD42016036732Electronic supplementary materialThe online version of this article (doi:10.1186/s13643-016-0326-1) contains supplementary material, which is available to authorized users.

2014 Consensus conference on viscoelastic test–based transfusion guidelines for early trauma resuscitation

There has been an increased interest in the use of viscoelastic testing to guide blood product replacement during the acute resuscitation of the injured patient. Currently, no uniformly accepted guidelines exist for how this technology should be integrated into clinical care. In September 2014, an international multidisciplinary group of leaders in the field of trauma coagulopathy and resuscitation was assembled for a 2-day consensus conference in Philadelphia, Pennsylvania. This panel included trauma surgeons, hematologists, blood bank specialists, anesthesiologists, and the lay public.Nine questions regarding the impact of viscoelastic testing in the early resuscitation of trauma patients were developed before the conference by panel consensus. Early use was defined as baseline viscoelastic test result thresholds obtained within the first minutes of hospital arrival-when conventional laboratory results are not available. The available data for each question were then reviewed in person using standardized presentations by the expert panel. A consensus summary document was then developed and reviewed by the panel in an open forum. Finally, a two-round Delphi poll was administered to the panel of experts regarding viscoelastic thresholds for triggering the initiation of specific treatments including fibrinogen, platelets, plasma, and prothrombin complex concentrates. This report summarizes the findings and recommendations of this consensus conference.

TEG® and ROTEM® in trauma: similar test but different results?

IntroductionTransfusion in trauma is often empiric or based on traditional lab tests. Viscoelastic tests such as thromboelastography (TEG®) and rotational thromboelastometry (ROTEM®) have been proposed as superior to traditional lab tests. Due to the similarities between the two tests, general opinion seems to consider them equivalent with interchangeable interpretations. However, it is not clear whether the results can be similarly interpreted. This review evaluates the comparability between TEG and ROTEM and performs a descriptive review of the parameters utilized in each test in adult trauma patients.MethodsPUBMED database was reviewed using the keywords “thromboelastography” and “compare”, between 2000 and 2011. Original studies directly comparing TEG® with ROTEM® in any area were retrieved. To verify the individual test parameter used in studies involving trauma patients, we further performed a review using the keywords “thromboelastography” and “trauma” in the PUBMED database.ResultsOnly 4 studies directly compared TEG® with ROTEM®. One in liver transplantation found that transfusion practice could differ depending on the device in use. Another in cardiac surgery concluded that all measurements are not completely interchangeable. The third article using commercially available plasma detected clinically significant differences in the results from the two devices. The fourth one was a head-to-head comparison of the technical aspects. The 24 articles reporting the use of viscoelastic tests in trauma patients, presented considerable heterogeneity.ConclusionBoth tests are potentially useful as means to rapidly diagnose coagulopathy, guide transfusion and determine outcome in trauma patients. Differences in the activators utilized in each device limit the direct comparability. Standardization and robust clinical trials comparing the two technologies are needed before these tests can be widely recommended for clinical use in trauma.