TEG top references from literature review
Authors A-C
- Akay OM, Ustuner Z, Canturk Z, Mutlu FS, Gulbas Z. Laboratory investigation of hypercoagulability in cancer patients using rotation thrombelastography. Med Oncol 2009;26:358-364. RoTEM analysis of patients with a variety of different cancers were evaluated using RoTEM analysis. The patients were all found to be hypercoagulable based on RoTEM parameters, especially clot strength and CFT (clot formation time) parameters. Clot strength and CFT were correlated with fibrinogen levels and platelet counts.
- Anderson L, Quasim I, Soutar R, Steven M, Macfie A, Korte W. An audit of red cell and blood product use after the institution of thromboelastometry in a cardiac intensive care unit. Transfus Med 2006;16:31-39. The effect RoTEM analysis for cardiac surgery patients on transfusion rates was studied by retrospectively comparing 488 patients six months before and 502 patients six months after implementation. RoTEM analysis significantly reduced the number of blood products used. The RoTEM-guided algorithm is presented.
- Beilin Y, Arnold I, Hossain S. Evaluation of the platelet function analyzer (PFA-100) vs. the thromboelastogram (TEG) in the parturient. Int J Obstet Anesth 2006;15:7-12. The results of this observational study of 172 healthy term parturients found that there was no correlations between CT (clotting time) with the PFA-100 and platelet count or between CT and MA. A significant correlation was found between platelet count and MA (r=0.33, p<0.001). Since thrombocytopenia is the most common hematologic disorder during pregnancy, TEG analysis may be a better tool to evaluate coagulation in the parturient with thrombocytopenia.
- Bliden KP, DiChiara J, Tantry US, Bassi AK, Chaganti SK, Gurbel PA. Increased risk in patients with high platelet aggregation receiving chronic clopidogrel therapy undergoing percutaneous coronary intervention: is the current antiplatelet therapy adequate? J Am Coll Cardiol 2007;49:657-666. This prospective study used ADP-induced responsiveness of platelets, measured by platelet aggregation and TEG analysis (PlateletMapping), to determine the risk for post-PCI thromboembolic events (n=100 patients). The cutoff level for normal ADP-induced on-treatment platelet reactivity was defined as ≥ 70% for the TEG (≥ 50% for platelet aggregation). A strong correlation between platelet aggregation and the ADP PlateletMapping results was found (r = 0.82 p ≤ 0.0001). The results demonstrate that patients exhibiting high on-treatment ADP-induced aggregation (≥ 70%), as measured by TEG PlateletMapping, are at increased risk for recurrent ischemic events.
- Bochsen L, Rosengaard LB, Nielsen AB, Steinbruchel DA, Johansson PI. Platelet hyperreactivity in response to on- and off-pump coronary artery bypass grafting. J Extra Corpor Technol. 2009 Mar;41(1):15-9. Platelet hypercoagulability was prospectively evaluated using the TEG-MA value in patients undergoing CABG surgery with and without CPB. The major finding of this study was that all patients experienced a significant increase in TEG-MA value by post-op day 4. Patients presenting with a high MA (> 69 mm) preoperatively remained at the high level at post-op day 30.
- Bochsen L, Wiinberg B, Kjelgaard-Hansen M, Steinbruchel DA, Johansson PI. Evaluation of the TEG platelet mapping assay in blood donors. Thromb J 2007;5:3. The natural inhibition at the platelet ADP receptor and within the AA pathway were studied in a population of blood donors (n=43). The study revealed a high level of ADP receptor variability in this population (26%) compared to MAthrombin (3%) and MA-AA (7%). The coefficient of variation was calculated for the PlateletMapping assay (< 6%).
- Bowbrick VA, Mikhailidis DP, Stansby G. Influence of platelet count and activity on thromboelastography parameters. Platelets 2003;14:219-224. The contribution of platelet number to TEG parameters was examined in this study. A strong linear correlation was found between Log10[platelet count] and MA (r= 0.97) and K (r=-0.86). The strength of the correlations was reduced for PAD patients compared to controls. The results suggest that both the MA and K values are useful for assessing platelet transfusion needs.
- Bolliger D, Szlam F, Molinaro RJ, Rahe-Meyer N, Levy JH, Tanaka KA. Finding the optimal concentration range for fibrinogen replacement after severe haemodilution: an in vitro model. Br J Anaesth. 2009 Jun;102(6):793-9. Epub 2009 May 6. An in vitro model of dilutional coagulopathy was used to determine the level of fibrinogen required to normalize fibrin polymerization as demonstrated by RoTEM analysis. Two principle findings of this study are: 1) fibrinogen levels > 200 mg/dL are necessary to improve clot formation after hemodilution with saline, which is twice the level suggested by current transfusion guidelines, and 2) hemodilution increases the vulnerability of clots to fibrinolysis and fibrinogen replacement is not able to decrease clot vulnerability to tPA-induced lysis.
- Brohi K. Diagnosis and management of coagulopathy after major trauma. Br J Surg 2009;96:963-964. This is a short review article about trauma-induced coagulopathy (TIC) and the factors associated with the development of the coagulopathy. Early recognition of TIC can lead to early and aggressive treatment to correct the coagulopathy.
- Cammerer U, Dietrich W, Rampf T, Braun SL, Richter JA. The predictive value of modified computerized thromboelastography and platelet function analysis for postoperative blood loss in routine cardiac surgery. Anesth Analg. 2003 Jan;96(1):51-7. The ability of RoTEM analysis to predict post-operative bleeding was studied in this prospective observational study of cardiac surgery patients (n=255). RoTEM analysis was found to have a low ability to predict post-operative blood loss (< 40%). A small positive predictive value with many false-positive results suggests that not every hemostatic defect inevitably causes abnormal post operative bleeding. However, if an abnormal RoTEM analysis coincides with clinically signficant bleeding, the bleeding should be treated to correct the coagulopathy. RoTEM analysis was found to have a high negative predictive value (> 77%) in this study.
- Carr ME, Jr., Carr SL. Fibrin structure and concentration alter clot elastic modulus but do not alter platelet mediated force development. Blood Coagul Fibrinolysis 1995;6:79-86. This study uses platelet-mediated force development as an index of clotting ability. The results demonstrate that force development is dependent on platelet function whereas the elastic modulus is dependent on the platelet/fibrin network. The study also found that increasing fibrinogen concentration resulted in the generation of thin fibrin fibers and increased the elastic modulus with minimal effect on platelet force development.
- Carroll RC, Craft RM, Langdon RJ, et al. Early evaluation of acute traumatic coagulopathy by thrombelastography. Transl Res 2009;154:34-39. The coagulation changes during the golden hour of trauma patients (n=161) were monitored using TEG analysis and PlateletMapping in this prospective observational study. The MA-ADP value was significantly associated with transfusion requirements of patients. The R, MA, and MA-fibg (fibrinogen level from PlateletMapping assay) values were all significantly correlated with mortality.
- Cerutti E, Stratta C, Romagnoli R, et al. Thromboelastogram monitoring in the perioperative period of hepatectomy for adult living liver donation. Liver Transpl 2004;10:289-294. This study examined the changes in hemostatic status of patients undergoing hepatectomy for living donor liver transplantation using TEG analysis. Despite the suggestion of hypocoagulability by the routine tests of coagulation, TEG monitoring identified a progressive hypercoagulability in the majority of the subjects after hepatectomy. The authors suggest that TEG monitoring could be useful in the perioperative management of donors to guide antithrombotic treatment and increase the safety of the procedure.
- Chakroun T, Gerotziafas GT, Seghatchian J, Samama MM, Hatmi M, Elalamy I. The influence of fibrin polymerization and platelet-mediated contractile forces on citrated whole blood thromboelastography profile. Thromb Haemost. 2006 May;95(5):822-8. This study examined the influence of fibrin polymerization and platelet actin polymerization on the different phases ofclot formation using TEG analysis. The study found that R and K parameters are dependent on fibrin polymerization, but not platelet function; the alpha parameter is dependent on both fibrin polymerization and platelet function; and clot strength (MA and G) is dependent on platelet contractile force (i.e. platelet actin polymerization).
- Choong CK, Gerrard C, Goldsmith KA, Dunningham H, Vuylsteke A. Delayed re-exploration for bleeding after coronary artery bypass surgery results in adverse outcomes. Eur J Cardiothorac Surg 2007;31:834-838. The aim of this retrospective study was to determine the impact of delaying re-exploration (> 12 hrs) for bleeding after cardiac surgery. No significant difference in blood loss or transfusion requirements was found between the two groups. Patients requiring re-exploration for bleeding were found to be at a higher risk of adverse outcomes and the risk was increased if time to re-exploration was delayed to > 12 hr. The results strongly suggest a policy of early reexploration for bleeding.
- Coakley M, Reddy K, Mackie I, Mallett S. Transfusion triggers in orthotopic liver transplantation: a comparison of the thromboelastometry analyzer, the thromboelastogram, and conventional coagulation tests. J Cardiothorac Vasc Anesth 2006;20:548-553. The TEG and RoTEM were compared regarding their ability to determine transfusion needs of patients undergoing liver transplant. The results demonstrated that either device would provide the necessary information, but that transfusion practice would vary relative to the coagulation monitoring system used. The transfusion of platelets or fibrinogen to correct low MA values was discussed in detail, suggesting that fibrinogen levels should be normalized before transfusion of platelets.
- Collet JP, Shuman H, Ledger RE, Lee S, Weisel JW. The elasticity of an individual fibrin fiber in a clot. Proc Natl Acad Sci 2005;102:9133-9137. This study examined the viscoelastic properties of clots, specifically the relationship between elasticity and fibrin fiber structure. The importance of the visoelastic properties of clots to hemostasis is discussed.
- Collyer TC, Gray DJ, Sandhu R, Berridge J, Lyons G. Assessment of platelet inhibition secondary to clopidogrel and aspirin therapy in preoperative acute surgical patients measured by thrombelastography Platelet Mapping. Br J Anaesth. 2009 Apr;102(4):492-8. This prospective observational study examined the level of platelet inhibition, using TEG PlateletMapping (TEG-PM), of patients requiring emergent orthopedic surgery (n=59). There were three groups of patients: control (no known antiplatelet drugs), on aspirin therapy, and on clopidogrel therapy. The results showed that TEG-PM was able to detect significant platelet inhibition in the aspirin and clopidogrel groups and that discontinuation of clopidogrel led to a gradual recovery of platelet function over time. Significant variability of platelet inhibition was seen within all the groups. The cause of the variability in the control group was unknown.
- Craft RM, Chavez JJ, Bresee SJ, Wortham DC, Cohen E, Carroll RC. A novel modification of the Thrombelastograph assay, isolating platelet function, correlates with optical platelet aggregation. J Lab Clin Med. 2004 May;143(5):301-9. This paper provides a good overview on the development of the PlateletMapping assay. A description of the assay is provided and initial results with measuring platelet inhibition by NSAIDs, clopidogrel, and GPIIb/IIIa inhibitors are discussed. Linear regression analysis comparing PlateletMapping with optical platelet aggregation (with PRP) was conducted and yielded an r2 value of 0.65. (see figure 5).
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Authors D-G
- Dai Y, Lee A, Critchley LA, White PF. Does thromboelastography predict postoperative thromboembolic events? A systematic review of the literature. Anesth Analg. 2009 Mar;108(3):734-42. A systemic review of the literature (1998-2005) was conducted to determine the relationship between TEG-y analysis and the incidence of postoperative thromboembolic events (TE). Although 10 studies were identified for analysis, a meta-analysis was not possible due to a lack of standardization of methodology and definition of hypercoagulability. Although the clot strength (MA or MCF) appeared to be the best parameter for defining a hypercoagulable state, there has been no consensus regarding the minimum threshold clot strength level that should be used to predict TE events. The paper discussed the quality of the studies and concluded that additional prospective randomized studies are needed.
- Davidson SJ, McGrowder D, Roughton M, Kelleher AA. Can ROTEM thromboelastometry predict postoperative bleeding after cardiac surgery? J Cardiothorac Vasc Anesth 2008;22:655-661. This prospective observational study found that the ability of RoTEM analysis to predict post-operative bleeding in primary CABG patients (n=58) was poor (15%), but the negative predictive ability (in absence of surgical bleeding, normal values indicate that a patient is unlikely to bleed excessively) was high (94%). These results support the frequent clinical observation that impaired hemostasis, as indicated by an abnormal TEGy, is not always associated with significant postoperative hemorrhage, highlighting the importance of linking TEGy results with clinical status of the patient.
- Dempfle CE, Kalsch T, Elmas E, et al. Impact of fibrinogen concentration in severely ill patients on mechanical properties of whole blood clots. Blood Coagul Fibrinolysis 2008;19:765-770. This prospective observational study examined the relationship between the mechanical properties of clots and fibrinogen levels in blood samples collected from surgical ICU patients (n=522 blood samples). Clot elastic modulus and platelet contractile force were measured using the Hemodyne device. The results demonstrated that the mechanical properties of clots progressively improve with increasing fibrinogen concentrations. A threshold fibrinogen level of 1 g/L was observed for the PT and aPTT. At fibrinogen levels > 1 g/L there was no significant effect on clotting times. The relationship between TEG and Hemodyne results was discussed.
- Despotis G, Eby C, Lublin DM. A review of transfusion risks and optimal management of perioperative bleeding with cardiac surgery. Transfusion 2008;48:2S-30S. The effects of transfusions, including transfusion reactions, immune modulation, multi-organ failure, and the impact of transfusions on survival are reviewed in this paper. Also reviewed are the mechanisms associated with perioperative bleeding and the common treatments for bleeding, including transfusions and drugs. The role of point-of-care tests to optimize treatment type and timing is also discussed. The efficacy of rFVIIa for treating perioperative bleeding in cardiac surgery patients is reviewed.
- Despotis GJ, Joist JH, Goodnough LT. Monitoring of hemostasis in cardiac surgical patients: impact of point-of-care testing on blood loss and transfusion outcomes. Clin Chem 1997;43:1684-1696. The CBP-induced hemostatic alterations are reviewed in this article as well as the methodologies that can be used to monitor the type and magnitude of the alterations.
- Engoren MC, Habib RH, Zacharias A, Schwann TA, Riordan CJ, Durham SJ. Effect of blood transfusion on long-term survival after cardiac operation. Ann Thorac Surg 2002;74:1180-1186. This is one of the first retrospective studies (n=1950) to link blood transfusions with survival in cardiac patients, specifically patients undergoing primary CABG surgery, typically a population at low risk for bleeding complications. It was found that transfused patients had twice the 5-year mortality than non-transfused patients. Correction for co-morbidities still resulted in a 70% increase in mortality for transfused compared to non-transfused patients.
- Essell JH, Martin TJ, Salinas J, Thompson JM, Smith VC. Comparison of thromboelastography to bleeding time and standard coagulation tests in patients after cardiopulmonary bypass. J Cardiothorac Vasc Anesth 1993;7:410-415. The results from this prospective study (n=36) demonstrate the high specificity of TEG analysis (89.3%) over the bleeding time, platelet count, PT, and PTT in cardiac surgery patients. The negative predictive value for detection of bleeding with TEG analysis was found to be 92.3%, whereas the positive predictive value was only 62.5%. The K, alpha, and MA were all significantly different between bleeders and nonbleeders.
- Fenger-Eriksen C, Ingerslev J, Sorensen B. Fibrinogen concentrate--a potential universal hemostatic agent. Expert Opin Biol Ther 2009;9:1325-1333. This review article discusses the use of fibrinogen concentrate to correct hemostatic defects for patients with acquired fibrinogen deficiency. The pharmacology and pharmacokinetics of fibrinogen are presented. Fibrinogen deficiency appears to be an early event in seriously bleeding patients, preceding critical levels of platelets or other coagulation factors. Clinical observations suggest a beneficial role of early substitution with fibrinogen in management of critical traumatic and surgical bleeds.
- Fenger-Eriksen C, Jensen TM, Kristensen BS, et al. Fibrinogen substitution improves whole blood clot firmness after dilution with hydroxyethyl starch in bleeding patients undergoing radical cystectomy: a randomized, placebo-controlled clinical trial. J Thromb Haemost 2009;7:795-802. A dilutional coagulopathy was induced in patients undergoing cystectomy by resuscitation with HES 130/0.4 after a massive bleeding episode. After hemodilution, the patients (n=20) were randomized to be treated with placebo or fibrinogen concentrate. RoTEM analysis showed that dilution with HES solution significantly reduced clot strength. Hemostatic intervention with fibrinogen concentrate significantly improved clot strength and maximum velocity of clot formation, and reduced the number of PRBCs transfused.
- Fenger-Eriksen C, Tonnesen E, Ingerslev J, Sorensen B. Recombinant factor VIIa and fibrinogen display additive effect during in vitro haemodilution with crystalloids. Acta Anaesthesiol Scand 2009;53:332-338. The effect of combining fibrinogen concentrate and rFVIIa in an in vitro dilutional coagulopathy model was examined using RoTEM analysis. Dilution at 50% with crystalloid solution significantly altered the clot formation parameters and clot strength. Addition of fibrinogen concentrate improved clot propagation and clot strength, whereas addition of rFVIIa alone improved clot initiation time. Addition of both fibrinogen and rFVIIa improved all parameters, suggesting an additive effect. Hemodilution with crystalloid did not produce a hypercoagulable state as demonstrated in previous hemodilution studies.
- Fries D, Innerhofer P, Schobersberger W. Time for changing coagulation management in trauma-related massive bleeding. Curr Opin Anaesthesiol 2009;22:267-274. This review article covers the pathophysiology of the coagulopathy experienced by massively bleeding patients. The treatment options, such as rFVIIa, FXIII, antifibrinolytics, prothrombin complex concentrate, and fibrinogen concentrate are reviewed. Finally, a massive transfusion protocol which includes RoTEM measurements is presented and discussed.
- Gallimore MJ, Harris SL, Tappenden KA, Winter M, Jones DW. Urokinase induced fibrinolysis in thromboelastography: a model for studying fibrinolysis and coagulation in whole blood. J Thromb Haemost 2005;3:2506-2513. A modified TEG assay was used to examine the role of contact activation of FXIIa and kallikrein on fibrinolysis in whole blood. The results show that fibrinolysis occurs when a threshold level of urokinase is added to the blood sample and that this threshold varies between patients, likely due to platelet number, total fibrin formation, fibrin cross linking, and concentrations of plasminogen and fibrinolytic inhibitors. Results also suggest that the activation of FXII and kallikrein both play a role in activating fibrinolysis.
- Ganter MT, Hofer CK. Coagulation monitoring: current techniques and clinical use of viscoelastic point-of-care coagulation devices. Anesth Analg 2008;106:1366-1375. The characteristics of the three visco-elastic coagulation monitoring devices are presented in this review. Both the technical and clinical descriptions of the three devices are provided, including the definitions of all the measurement parameters. The clinical applications of these devices are also discussed.
- Gologorsky E, De Wolf AM, Scott V, Aggarwal S, Dishart M, Kang Y. Intracardiac thrombus formation and pulmonary thromboembolism immediately after graft reperfusion in 7 patients undergoing liver transplantation. Liver Transpl 2001;7:783-789. This is another report of thromboembolic complications during OLT. The mechanisms of this complication suggest an imbalance of the pro- and anti-coagulant pathways during the reperfusion phase.
- Gonano C KS, Panzer OP, Kozek SA, et al. Accuracy of native and activated thromboelastography for assessment of plasma fibrinogen levels. Anesthesiology 1998;89:3A. This is an abstract from a study that showed a significant correlation between the functional fibrinogen assay and the Clauss method of measuring fibrinogen (laboratory).
- Goto S. Understanding the mechanism and prevention of arterial occlusive thrombus formation by anti-platelet agents. Curr Med Chem Cardiovasc Hematol Agents 2004;2:149-156. This article provides an overview of the different roles that platelets play during clot development, including thrombin generation, fibrin formation, and the development of clot strength. The paper suggests that inhibition of the GPIIb/IIIa receptors might not be as effective in preventing thrombus formation as the inhibition of events prior to platelet aggregation.
- Gottumukkala VN, Sharma SK, Philip J. Assessing platelet and fibrinogen contribution to clot strength using modified thromboelastography in pregnant women. Anesth Analg 1999;89:1453-1455. The independent contributions of fibrinogen and platelets to clot strength were examined using a modified TEG assay in which ReoPro was used to inhibit platelet aggregation. The resulting MAfib correlated with plasma fibrinogen levels. There was no correlation between MAplt and platelet count, suggesting that clot strength depends on platelet function, not platelet count.
- Gurbel PA, Bliden KP, Guyer K, et al. Platelet reactivity in patients and recurrent events post-stenting: results of the PREPARE POST-STENTING Study. J Am Coll Cardiol 2005;46:1820-1826. Risk factors for the re-occurrence of an ischemic event after PCI were examined. MA, a marker of thrombin-induced platelet-fibrin aggregation, was more predictive of an ischemic event than platelet reactivity to ADP. The study suggests that high platelet reactivity to thrombin (high MA, > 72 mm) and accelerated thrombin generation (low R, < 5.1 min) after PCI are important predictive measurements for ischemic events in this population of patients.
- Gurbel PA, Bliden KP, Saucedo JF, et al. Bivalirudin and clopidogrel with and without eptifibatide for elective stenting: effects on platelet function, thrombelastographic indexes, and their relation to periprocedural infarction results of the CLEAR PLATELETS-2 (Clopidogrel with Eptifibatide to Arrest the Reactivity of Platelets) study. J Am Coll Cardiol 2009;53:648-657. This prospective randomized study examined the effects of different combinations of antiplatelet (clopidogrel and eptifibatide) and anticoagulant (bivalirudin) therapies on platelet reactivity and the incidence of thrombotic events following PCI. TEG analysis was used to determine thrombin induced platelet-fibrin clot strength (TIP-FCS or MA) and time to initial fibrin formation (R-value).The results demonstrated that patients with high TIP-FCS (> 63 mm) and high platelet reactivity (measured by platelet aggregation) were at greatest risk for developing periprocedural myocardial infarction.
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Authors H-L
- Hertfelder HJ, Bos M, Weber D, Winkler K, Hanfland P, Preusse CJ. Perioperative monitoring of primary and secondary hemostasis in coronary artery bypass grafting. Semin Thromb Hemost 2005;31:426-440. Hemostasis was monitored during CABG surgery with CPB using the PFA-100, platelet aggregation, bleeding time, TEG, PT, aPTT, and thrombin time. The primary finding of the study was that there were highly variable alterations in the hemostatic system even in patients assumed to be at a low risk of bleeding. The TEG was found to be useful in identifying post-CPB bleeding, whereas the PFA-100 was useful in identifying post-operative platelet hyperactivity.
- Hobson AR, Agarwala RA, Swallow RA, Dawkins KD, Curzen NP. Thrombelastography: current clinical applications and its potential role in interventional cardiology. Platelets 2006;17:509-518. This is a review article on TEG analysis and platelet function analysis, including a description of PlateletMapping.
- Hobson AR, Qureshi Z, Banks P, Curzen N. Gender and responses to aspirin and clopidogrel: insights using short thrombelastography. Cardiovasc Ther 2009;27(4):246-252. The intra-individual hemostatic variability was examined in this study. A gender difference in clotting tendency and platelet reactivity was found between women and men < 50 yrs in age. These differences were associated with differences in response to antiplatelet drugs and to thrombotic risk in younger women. TEG was used to measure the hemostatic status and the AUC15 method of interpreting PlateletMapping results.
- Horacek M, Cvachovec K. The effects of cardiopulmonary bypass with hollow fiber membrane oxygenator on blood clotting measured by thromboelastography. Physiol Res 2002;51:145-150. Using native TEG analysis, this prospective observational study of cardiac surgery patients found no change in clot strength, as measured by MA or G, with CPB. The use of the G value over the MA value is discussed.
- Huissoud C, Carrabin N, Audibert F, et al. Bedside assessment of fibrinogen level in postpartum haemorrhage by thrombelastometry. BJOG 2009;116:1097-1102. The ability of the FIBTEM test (RoTEM) to accurately determine fibrinogen levels in postpartum patients experiencing bleeding complications was prospectively studied. The study showed that FIBTEM results correlated with fibrinogen levels in a timely fashion and that a value of < 2 g/L was highly predictive (100% sensitivity and > 85% specificity) of bleeding in this population of patients. The changes that occur in the hemostatic system during pregnancy were discussed.
- Johansson PI. Hemostatic strategies for minimizing mortality in surgery with major blood loss. Curr Opin Hematol 2009;16:509-514. This article reviews the recent advances in the management of massive transfusion and changes in massive transfusion protocols. An argument for continuous monitoring of hemostasis, using TEG analysis, to guide FFP and platelet transfusions is made.
- Johansson PI. Treatment of massively bleeding patients: introducing real-time monitoring, transfusion packages and thrombelastography (TEG®). ISBT Sci Series 2007;2:159-167. This paper discusses the use of TEG analysis by the blood bank to monitor hemostatic status of patients requiring blood transfusions. The results of this hospital’s experience found that performing TEG analysis in only those patients with clinically significant bleeding reduced the number of analyses by 85%. TEG analysis also showed a 97% ability to predict a surgical cause of bleeding in post-operative patients.
- Johansson PI, Bochsen L, Stensballe J, Secher NH. Transfusion packages for massively bleeding patients: the effect on clot formation and stability as evaluated by Thrombelastograph (TEG). Transfus Apher Sci 2008;39:3-8. This small prospective study examined the effect of a balanced transfusion strategy for massively bleeding patients (n=10) on clot dynamics as shown by TEG analysis. The results demonstrate that administration of a balanced transfusion strategy is able to normalize clot formation and structure.
- Johansson PI, Stensballe J. Effect of haemostatic control resuscitation on mortality in massively bleeding patients: a before and after study. Vox Sang 2009;96:111-118. The survival rate of patients experiencing massive bleeding (n= 442) and treated with a balanced transfusion package, consisting of comprising 5 units of PRBCs, 5 units of FFP and 2 units of platelet concentrates, were determined in this prospective cohort study. TEG analysis was used to guide administration of blood products after initial treatment with the transfusion package. The results demonstrated that aggressive treatment with this transfusion package and using a TEG-guided transfusion protocol improved survival.
- Johansson PI, Swiatek F, Jorgensen L, Jensen LP, Secher NH. Intraoperative platelet and plasma improves survival in patients operated for a rAAA: a follow-up evaluation. Eur J Vasc Endovasc Surg 2008;36:397-400. This prospective observational study examined the effect of aggressive administration of transfusion packages consisting of PRBC, FFP and platelets to patients requiring rAAA surgery. The results demonstrate that implementation of a transfusion protocol for massively bleeding patients aimed at providing timely and balanced delivery of blood components to prevent, rather than to ‘‘catch up’’ with a developing coagulopathy, improved patient outcomes.
- Juttner B, Brock J, Weissig A, et al. Dependence of platelet function on underlying liver disease in orthotopic liver transplantation. Thromb Res 2009;124:433-438. Platelet function abnormalities in different types of liver disease were examined in this study using flow cytometry and platelet aggregation assays. Different types and levels of platelet dysfunction were associated with different types of liver disease, as well as at different phases of the transplant surgery. This paper also provides a good discussion of the coagulopathies of liver disease and the changes associated with liver transplantation.
- Kamal AH, Tefferi A, Pruthi RK. How to interpret and pursue an abnormal prothrombin time, activated partial thromboplastin time, and bleeding time in adults. Mayo Clin Proc 2007;82:864-873. This paper provides a good overview of the PT and aPTT assays and the limitations relating to the prediction of bleeding or thrombotic complications in patients.
- Karlsson M, Ternstrom L, Hyllner M, Baghaei F, Nilsson S, Jeppsson A. Plasma fibrinogen level, bleeding, and transfusion after on-pump coronary artery bypass grafting surgery: a prospective observational study. Transfusion 2008;48:2152-2158. The relationship between fibrinogen level and post-operative bleeding was examined in a prospective observational study of patients undergoing CABG surgery with CPB. The results demonstrated that a preoperative plasma fibrinogen concentration (Clauss method) is a limiting factor for post-operative hemostasis. Previous studies suggested that a fibrinogen plasma level of higher than 1.0 g/L is sufficient to ensure that adequate hemostasis. These results suggest that fibrinogen levels > 1.0 g/L may be required when the hemostatic system is challenged by cardiac surgery and CPB.
- Karnicki K, Owen WG, Miller RS, McBane RD. Factors contributing to individual propensity for arterial thrombosis. Arterioscler Thromb Vasc Biol 2002;22:1495-1499.
The variability of the hemostatic response was found to be due to the heterogeneity of blood components, especially platelets, rather than differences in the vascular component.
- Kashuk JL, Moore EE, Sabel A, et al. Rapid thrombelastography (r-TEG) identifies hypercoagulability and predicts thromboembolic events in surgical patients. Surgery 2009;146:764-772. Surgical ICU patients (n=172) were retrospectively analyzed to determine if Rapid TEG analysis could identify patients who experienced a thrombotic event within 72 hrs of hospitalization. The G-value was used to evaluate hypercoagulability in these patients. The results showed that the G-value (G > 13.5 dynes/cm2) had a high sensitivity and specificity for identifying patients at risk for a thrombotic event. No patients with a G < 13.4 dynes/cm2 experienced a thrombotic event. The results suggest that Rapid TEG G-value could be used as a screening tool for identifying ICU patients at risk for a thrombotic event.
- Katori N, Szlam F, Levy JH, Tanaka KA. A novel method to assess platelet inhibition by eptifibatide with thrombelastograph. Anesth Analg 2004;99:1794-1799. This paper provides background information on the PlateletMapping assay. Specifically it examines the use of batroxobin, a thrombin-like enzyme that cleaves fibrinogen, but does activate platelets, to activate fibrin clot formation in heparinized blood. The different effects of citrate and heparin on platelet inhibition by eptifibatide are studied and discussed. The Platelet Works platelet aggregation results were compared with the TEG results. A short description of the Platelet Works device is provided.
- Kaufmann CR, Dwyer KM, Crews JD, Dols SJ, Trask AL. Usefulness of thrombelastography in assessment of trauma patient coagulation. J Trauma. 1997 Apr;42(4):716-20. This is one of the first papers describing the use of TEG analysis in trauma patients. TEG analysis found that a large number of trauma patients were hypercoagulable and was a better predictor of transfusion requirements in blunt trauma patients compared to the PT, aPTT, or platelet count.
- Lerner AB, Sundar E, Mahmood F, Sarge T, Hanto DW, Panzica PJ. Four cases of cardiopulmonary thromboembolism during liver transplantation without the use of antifibrinolytic drugs. Anesth Analg 2005;101:1608-1612. Orthotopic liver transplantation (OLT) is typically associated with bleeding complications requiring large numbers of blood products. This report discusses the four cases of thromboembolic events during OLT. Although thromboembolism during OLT is rare, the results have a significant impact on the outcome of the patients. The authors discuss the importance of being able to identify the condition and consider the use of the TEG as a way to assess hypercoagulability in these patients.
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Lombard FW, Welsby IJ, Alexander MJ, Borel CO. Thromboelastography detects inadequate response to abciximab therapy during stent-assisted cerebral aneurysm coil embolization complicated by stroke. Neurocrit Care 2006;4:32-34. The case study of a patient who received abciximab (GPIIb/IIIa inhibitor) therapy following stent-assisted cerebral aneurysm coil embolization and complicated by thromboembolic stroke is described. The abciximab rescue therapy failed and was associated with a poor neurological outcome. Standard TEG analysis and platelet aggregometry both suggested inadequate platelet inhibition, but PFA-100 suggested adequate inhibition. The use of TEG analysis to individualize abciximab dosing is recommended to improve outcomes.
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Authors M-R
- Manji M, Isaac JL, Bion J. Survival from massive intraoperative pulmonary thromboembolism during orthotopic liver transplantation. Br J Anaesth 1998;80:685-687. This is another case study of a thromboembolic complication during OLT.
- Mann KG, Brummel-Ziedins K, Undas A, Butenas S. Does the genotype predict the phenotype? Evalulations of the hemostatic proteome. J Thromb Haemost 2004;2:1727-1734. The variability of the hemostatic response, the factors contributing to the variability, and the consequences of the variability relative to diagnosis and therapy are discussed in this article.
- Mann KG, Butenas S, Brummel K. The dynamics of thrombin formation. Arterioscler Thromb Vasc Biol 2003;23:17-25. This highly technical paper reviews the current models of thrombin generation, including an in depth discussion of the positive and negative feedback processes that regulate the rate and amount of thrombin generated when the coagulation system is activated. The clinical implications of these findings are discussed.
- Martini WZ, Cortez DS, Dubick MA, Park MS, Holcomb JB. Thrombelastography is better than PT, aPTT, and activated clotting time in detecting clinically relevant clotting abnormalities after hypothermia, hemorrhagic shock and resuscitation in pigs. J Trauma 2008;65:535-543. The contribution of hypothermia (39°C to 32°C) and hemorrhage (35% blood loss) with resuscitation to coagulation in a swine model were examined using routine coagulation tests, fibrinogen levels, thrombin generation and tissue factor activated TEG analysis. Both hypothermia and hemorrhage caused changes in coagulation as determined by TEG analysis, but in different ways. Hypothermia altered the rate of whole blood clot formation, whereas hemorrhage caused changes in clot strength. Neither hypothermia nor hemorrhage caused significant changes in the PT or aPTT tests, but platelet counts and thrombin generation were significantly decreased by hypothermia and/or hemorrhage with fluid resuscitation. Compared to PT and aPTT, TEG analysis appears to be a better test to detect mechanisms associated with coagulation abnormalities induced by hypothermia and hemorrhage. The limitations of PT and aPTT tests were discussed.
- Mittermayr M, Streif W, Haas T, et al. Hemostatic changes after crystalloid or colloid fluid administration during major orthopedic surgery: the role of fibrinogen administration. Anesth Analg 2007;105:905-917. The role of dilutional coagulopathy on clot formation was studied in a prospective series of orthopedic surgery patients using the RoTEM device. Three different solutions (HES, gelatin and Lactated Ringers) were administered to patients during surgery. The principle finding of this study was that impairment of fibrinogen polymerization was the main problem underlying dilutional coagulopathy, resulting in decreased total clot strength. In general, HES caused more impairment than an equal volume of crystalloid. The discussion provides a good overview of the pathophysiology associated with dilutional coagulopathies.
- Monroe DM, Hoffman M. What does it take to make the perfect clot? Arterioscler Thromb Vasc Biol 2006;26:41-48. This article reviews the cell based model of hemostasis, explains the deficiencies of the cascade model, and discusses the important role of thrombin and thrombin generation to clot formation.
- Mousa SA, Bozarth JM, Seiffert D, Feuerstein GZ. Using thrombelastography to determine the efficacy of the platelet glycoprotein IIb/IIIa antagonist, roxifiban, on platelet/fibrin-mediated clot dynamics in humans. Blood Coagul Fibrinolysis. 2005;16:165-171. This study used the TEG and its ability to measure the properties of the platelet/fibrin network to examine the efficacy of different classes of GPIIb/IIIa inhibitors. The study found that there was a difference in the efficacy of GPIIb/IIIa inhibitors to inhibit platelet aggregation versus clot strength (MA), suggesting that the clinical efficacy of these drugs may be linked to the ability to inhibit the development of sufficient clot strength and not just inhibition of platelet aggregation.
- Nielsen VG. A comparison of the Thrombelastograph and the ROTEM. Blood Coagul Fibrinolysis 2007;18:247-252. This prospective study compared TEG and ROTEM analysis using similar blood samples. The results demonstrated that TEG and RoTEM analysis provide similar data, but only if the samples were activated with the same exogenous activator in both devices. The study suggests that the level of coagulation activation generated by different activators will generate clinically significant differences in hemostatic data. Since different activators are used for TEG and RoTEM analysis, the results are not equivalent. Thus algorithms should be developed for each device.
- Nielsen VG, Geary BT, Baird MS. Evaluation of the contribution of platelets to clot strength by thromboelastography in rabbits: the role of tissue factor and cytochalasin D. Anesth Analg 2000;91:35-39. The contribution of platelets to clot strength was examined using rabbit blood, cytochalasin-D to inhibit platelet contraction, and tissue factor as an activator. The G value rather than MA was used as the parameter for clot strength. It was found that platelets contribute ~94% to tissue factor activated clot strength. A comparison of the MA and G values was discussed. The variability of platelet contribution to clot strength was also discussed.
- O'Connor CJ, Roozeboom D, Brown R, Tuman KJ. Pulmonary thromboembolism during liver transplantation: possible association with antifibrinolytic drugs and novel treatment options. Anesth Analg. 2000 Aug;91(2):296-9. This is a report of two cases of pulmonary embolism during OLT. This report highlights the probability of thromboembolic events during OLT, despite the general tendency of bleeding complications in these patients.
- Oshita K, Az-ma T, Osawa Y, Yuge O. Quantitative measurement of thromboelastography as a function of platelet count. Anesth Analg. 1999 Aug;89(2):296-9. The relationship between platelet counts and MA was examined in this study using human blood. It was found that MA was linearly related to the log10(platelet count) and a critical platelet count of 66 x 103/μL exists, below which clot strength is insufficient to achieve an appropriate level of hemostasis. A relationship between K and platelet count was also observed, but platelet count was not considered a primary determinant of the rate of clot formation. Finally, significant intra-patient variability was observed for the critical platelet count required for adequate hemostasis.
- Paparella D, Brister SJ, Buchanan MR. Coagulation disorders of cardiopulmonary bypass: a review. Intensive Care Med 2004;30:1873-1881. This paper is a good overview of how CPB disrupts coagulation and the consequences of those disruptions.
- Park MS, Martini WZ, Dubick MA, et al. Thromboelastography as a better indicator of hypercoagulable state after injury than prothrombin time or activated partial thromboplastin time. J Trauma 2009;67:266-275. The presence of a hypercoagulable state in nonbleeding burned (n=33) or nonburned (n=25) trauma patients was measured using routine coagulation tests and tissue factor activatedTEG analysis. The results suggest that TEG analysis is more sensitive that the PT or aPTT for detection of hypercoagulability in this population of patients. Despite standard DVT prophylaxis, the patients were in a hypercoagulable state between one to seven days after injury and 6% of patients developed DVT. TEG analysis could not distinguish patients who developed a DVT from those who did not. This paper provides a good discussion of the limitations of the PT and aPTT tests and the benefits of TEG analysis.
- Perez de Prado A, Cuellas C, Diego A, et al. Influence of platelet reactivity and response to clopidogrel on myocardial damage following percutaneous coronary intervention in patients with non-st-segment elevation acute coronary syndrome. Thromb Res 2009;124:678-82. The objective of this study was to determine the relationship between platelet reactivity, as measured by the Verify-Now device, and the incidence of myocardial damage in patients following percutaneous coronary intervention (PCI). In addition to a wide variability of patient responsiveness to clopidogrel, the results demonstrated that the measure of platelet reactivity post drug treatment was a better predictor of myocardial damage post-PCI than the actual response to clopidogrel.
- Plotkin AJ, Wade CE, Jenkins DH, et al. A reduction in clot formation rate and strength assessed by thrombelastography is indicative of transfusion requirements in patients with penetrating injuries. J Trauma 2008;64:S64-68. This retrospective study examined the ability of coagulation assays to predict transfusion requirements of patients (n=44) presenting to a combat hospital with penetrating injuries. Patients with MA values < 54 mm required significantly more blood products. The PT, PTT, and INR tests did not predict transfusion needs. A shortened R value (< 4 min) was observed in 59% of patients, however there were significant reductions in K, angle and MA, suggesting an overall hypocoagulable state.
- Priesman S. The risk of postoperative bleeding in patients receiving clopidogrel can be predicted using modified bed-side thromboelastography. EACTS Daily News 2009; Oct 20: 14. This article is a report of a prospective observational study conducted with patients undergoing CABG surgery. The patients (n=59) had previously been treated with aspirin (n=25) or aspirin and clopidogrel (n=34). The antiplatelet effects were monitored using the TEG PlateletMapping assay and the results were compared to the incidence of post-operative bleeding. PlateletMapping was able to identify bleeders from non-bleeders with a sensitivity of 78% and specificity of 84%, suggesting that PlateletMapping would be a good tool to individualize the treatment approach and to predict the risk of post-operative bleeding.
- Rahe-Meyer N, Pichlmaier M, Haverich A, et al. Bleeding management with fibrinogen concentrate targeting a high-normal plasma fibrinogen level: a pilot study. Br J Anaesth 2009;102:785-792. The initial correction of fibrinogen levels to at least 3.5 g/L (n=10 patients) was compared to the use of FFP and platelets (n=5 patients) to manage bleeding after CPB in this pilot study. The initial correction of fibrinogen levels was found to reduce bleeding and blood product utilization. Fibrinogen concentrate dosing was determined by the FIBTEM (RoTEM) assay and the use of a dosing equation. The following items were discussed in this article: the probable mechanism of action of high fibrinogen levels, the concept of a fibrinogen threshold value, and the recovery of fibrinogen levels of all patients by 24 hrs post-op.
- Rahe-Meyer N, Solomon C, Winterhalter M, et al. Thromboelastometry-guided administration of fibrinogen concentrate for the treatment of excessive intraoperative bleeding in thoracoabdominal aortic aneurysm surgery. J Thorac Cardiovasc Surg 2009;138:694-702. A RoTEM-based transfusion algorithm with correction of fibrinogen levels as the first step was compared to the algorithm without the fibrinogen step in patients undergoing repair of thoracoabdominal aortic aneurysm with CPB. Correction of fibrinogen level was determined by the FIBTEM assay using a threshold MA of 22 mm. The results of this small study showed that administration of fibrinogen concentrate as an initial therapy step, before following the standard transfusion algorithm, was associated with a reduction in the transfusion of platelets, FFP, and PRBC. The findings suggest a beneficial effect of fibrinogen concentrate as hemostatic agent for this population of surgical patients. The relationship of fibrinogen levels to hemostatic status was discussed in detail.
- Rao SV, Jollis JG, Harrington RA, et al. Relationship of blood transfusion and clinical outcomes in patients with acute coronary syndromes. JAMA 2004;292:1555-1562.
This large retrospective study (n=24112) examined the link between transfusions and the 30-day morbidity and mortality of patients treated for ischemic heart disease. Receiving a PRBC transfusion was associated with an increased morbidity and mortality, especially for patients with a nadir hematocrit of > 25%. The results from this study questions the practice of transfusing stable patients to a hematocrit > 25%.
- Reinhofer M, Brauer M, Franke U, Barz D, Marx G, Losche W. The value of rotation thromboelastometry to monitor disturbed perioperative haemostasis and bleeding risk in patients with cardiopulmonary bypass. Blood Coagul Fibrinolysis 2008;19:212-219. The association between post-operative bleeding and RoTEM analysis was studied in cardiac surgical patients (n=150) in this observational study. The FIBTEM MA value and the clot formation time of the ExTEM (TF-activated) assay were the parameters most closely associated with post-operative bleeding. These results suggest that the FIBTEM and ExTEM tests can identify patients who may benefit from hemostatic therapy, but they lack the sensitivity and specificity to function as a screening method for identifying patients with increased post-operative risk of bleeding. Only the late post-operative (> 1 hr post-protamine) assay results were predictive of blood loss. The results also demonstrated that intraoperative transfusion of PRBC impairs hemostasis and may increase the bleeding risk.
- Ren YH, Yang TS, Wang Y, et al. Evaluation of triple anti-platelet therapy by modified thrombelastography in patients with acute coronary syndrome. Chin Med J 2008;121:850-852. This study examines the use of PlateletMapping to monitor antiplatelet therapy at different time points in the treatment of patients (n=13) presenting with ACS and requiring PCI. Several interesting results were found: 1) initial clopidogrel therapy was ineffective in these patients but administration of tirofiban improved the level of ADP-mediated platelet inhibition. 2) patients without a history of taking aspirin were more resistant to initial aspirin therapy (300 mg), and 3) platelet hyperactivity in this population (Chinese) was defined at MA > 60 mm. The results demonstrate the usefulness of the PlateletMapping assay in determining the correct drug treatment for ACS.
- Roberts HR, Monroe DM, Escobar MA. Current concepts of hemostasis: implications for therapy. Anesthesiology 2004;100:722-730. This article provides a good overview of the cascade and cell based models of hemostasis and the implications for treatment with a variety of hemostatic drugs. Tables and figures included.
- Rogers MAM, Blumberg N, Saint S, Langai KM, Nallamothu BK. Hospital variation in transfusion and infection after cardiac surgery: a cohort study. BMC Med 2009;7:37. This retrospective study assessed the variation in transfusion practices of cardiac programs by evaluating 24,789 Medicare patients in Michigan. A wide variation in transfusion practice was found, with 30% being attributable to the program. In addition it was found that allogeneic, but not autologous blood transfusions increased the risk of in-hospital infections 2.0-fold, in-hospital mortality 4.0-fold, and 30-day mortality 3-fold.
- Rooney MM, Farrell DH, van Hemel BM, de Groot PG, Lord ST. The contribution of the three hypothesized integrin-binding sites in fibrinogen to platelet-mediated clot retraction. Blood. 1998 Oct 1;92(7):2374-81. This study discusses the importance of platelet function on clot retraction. The results demonstrate the importance of the interaction between fibrinogen and platelets to clot retraction and clot structure.
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Authors S-Z
- Selby R, Geerts W, Ofosu FA, et al. Hypercoagulability after trauma: hemostatic changes and relationship to venous thromboembolism. Thromb Res 2009;124:281-287. The association between the occurrence of venous thromboembolism (VTE) and a variety of hemostatic parameters was examined in a population of trauma patients (n=135). The study found that 59% of patients developed VTE, demonstrating a hypercoagulable tendency in trauma patients. Trauma results in a dysregulation of thrombin generation and non-specific increases of several acute phase proteins, but none of the laboratory hemostatic markers were associated with the development of VTE.
- Spalding GJ, Hartrumpf M, Sierig T, Oesberg N, Kirschke CG, Albes JM. Cost reduction of perioperative coagulation management in cardiac surgery: value of "bedside" thrombelastography (ROTEM). Eur J Cardiothorac Surg 2007;31:1052-1057. This study examined the cost-effectiveness of using a RoTEM-guided transfusion protocol for cardiac patients by comparing transfusion costs six months before (n=729) and six months (n=693) after implementation. The amount of platelet concentrates, pooled coagulation concentrates, rFVIIa, and FXIII were all significantly decreased, whereas fibrinogen concentrate use was significantly increased after implementation of the RoTEM protocol. These changes resulted in a 44% decrease in costs. The study demonstrates the cost effectiveness of a RoTEM based coagulation management program.
- Spiess BD, Gillies BS, Chandler W, Verrier E. Changes in transfusion therapy and reexploration rate after institution of a blood management program in cardiac surgical patients. J Cardiothorac Vasc Anesth 1995;9:168-173. Transfusion requirements for cardiac patients after implementation of TEG (n=591) was retrospectively compared with patients seven months prior to TEG analysis (n=488). TEG analysis significantly reduced the incidence of total transfusion from 83% to 79% during hospitalization, with the greatest decrease occurring in CABG patients. Specifically, TEG analysis was associated with a significant reduction in platelets (59 to 48% of patients) and FFP (36 to 26% of patients), but not cryoprecipitate. A significant reduction in PRBC transfusion also occurred due to a change in transfusion trigger. Re-exploration rate was also significantly reduced from 5.7% to 1.5%, with the TEG having a negative predictive value of >90%. The cost savings associated with TEG analysis being able to identify surgical bleeding was discussed.
- Spiess BD, Royston D, Levy JH, et al. Platelet transfusions during coronary artery bypass graft surgery are associated with serious adverse outcomes. Transfusion 2004;44:1143-1148. The link between platelet transfusions and the incidence of adverse effects was retrospectively examined for patients undergoing CABG surgery (n=1720). This study demonstrated that patients receiving one or more platelet transfusions were more likely to have increased risk of an adverse event during hospitalization. The study does not show a cause and effect link between platelet transfusions and adverse events, but it does suggest the need to consider a conservative approach to the use of platelets.
- Spiess BD, Tuman KJ, McCarthy RJ, DeLaria GA, Schillo R, Ivankovich AD. Thromboelastography as an indicator of post-cardiopulmonary bypass coagulopathies. J Clin Monit 1987;3:25-30. The ability of coagulation assays to predict post-operative bleeding of cardiac patients (n=38) was examined in this prospective observational study. TEG analysis was significantly better at predicting post-operative bleeding (87%) compared to RCT (51% accuracy) or ACT (30%).
- Spiezia L, Marchioro P, Radu C, et al. Whole blood coagulation assessment using rotation thrombelastogram thromboelastometry in patients with acute deep vein thrombosis. Blood Coagul Fibrinolysis 2008;19:355–360. Patients (n=30) presenting with acute DVT were evaluated before the start of anticoagulation therapy and compared with 40 matched control patients. RoTEM analysis (InTEM, ExTEM, FibTEM) was used in addition to the routine coagulation tests. Clot strength and AUC (area under the curve of first derivative (i.e. Vcurve)) were found to be significantly higher in DVT patients compared with controls. Fibrinogen levels were also significantly increased in DVT patients and were found to be correlated with AUC and clot strength for all RoTEM assays. No significant differences in RoTEM derived clotting time, PT, aPTT, and platelet counts were found. The results suggest that RoTEM analysis may be a useful tool for monitoring hemostatic status and guiding therapy in this population of patients.
- Stover EP, Siegel LC, Parks R, et al. Variability in transfusion practice for coronary artery bypass surgery persists despite national consensus guidelines: a 24-institution study. Institutions of the Multicenter Study of Perioperative Ischemia Research Group. Anesthesiology 1998;88:327-333.
The results of this study demonstrate that inappropriate transfusion practice continues to be an issue within cardiac surgery programs. An audit of the transfusion needs of different patient populations is recommended in order to define appropriate transfusion practices.
- Tripodi A, Chantarangkul V, Mannucci PM. Acquired coagulation disorders: revisited using global coagulation/anticoagulation testing. Br J Haematol. 2009; 147:77-82.
This paper provides a good overview of the limitations of the routine tests of coagulation, specifically the PT and aPTT. Comparison of the routine tests with the global tests of coagulation is also presented.
- Tripodi A, Primignani M, Chantarangkul V, et al. The coagulopathy of cirrhosis assessed by thromboelastometry and its correlation with conventional coagulation parameters. Thromb Res 2009;124:132-136. The RoTEM device was used to prospectively assess the hemostatic abnormalities of patients with cirrhotic liver disease (n=51). The results demonstrate that clot strength (MCF) was as good as the PT in categorizing the level of liver dysfunction. The limitations of the PT test were discussed. An interesting finding was the lack of association of the FIBTEM test with the level of liver dysfunction. The authors suggest that platelets, rather than coagulation factors, including fibrinogen, are the most important determinants in clot formation in cirrhotic patients.
- Tripodi A, Primignani M, Chantarangkul V, et al. An imbalance of pro- vs anti-coagulation factors in plasma from patients with cirrhosis. Gastroenterology 2009;137:2105-11. This study highlights the importance of examining the hemostatic status of patients with cirrhotic liver disease beyond the routine PT test. The plasma of patients with chronic cirrhosis was found to be normo- or hyper-coagulable based on thrombin generation assays. This hypercoagulability appears to be due to increased levels of factor VIII and decreased levels of protein C, resulting in an imbalance of the pro- and anti-coagulation pathways. These findings might explain the risk for venous thromboembolism in patients with chronic liver disease.
- Van PY, Cho SD, Underwood SJ, Morris MS, Watters JM, Schreiber MA. Thrombelastography versus AntiFactor Xa levels in the assessment of prophylactic-dose enoxaparin in critically ill patients. J Trauma 2009;66:1509-1515. The ability of kaolin activated TEG analysis and AntiXa levels to differentiate between ICU patients (n=61) who develop a DVT and those who do not despite enoxaparin therapy were prospectively studied. A comparison of TEG parameters between DVT and non-DVT patients showed a significant difference between the R time in enoxaparin-active vs. enoxaparin neutralized (with heparinase) samples. Non-DVT patients showed > 1.5 min difference, whereas there was no difference for DVT patients. AntiXa levels were not able to differentiate DVT from non-DVT patients. The results suggest that TEG analysis is better at determining the correct enoxaparin dose than AntiXa levels.
- Vanschoonbeek K, Feijge MA, Van Kampen RJ, et al. Initiating and potentiating role of platelets in tissue factor-induced thrombin generation in the presence of plasma: subject-dependent variation in thrombogram characteristics. J Thromb Haemost 2004;2:476-484. The factors associated with the variability of thrombin generation in PRP were examined using a thrombin generation assay technique. The onset and rate of thrombin generation were dependent on the exposure of phosphatidyl serine on the surface of platelets whereas the amount of thrombin generated was dependent on the balance of the procoagulant and anticoagulant activities in PRP. The ability of different antiplatelet agents to inhibit the thrombin generating process was also discussed. Inhibition of the GPIIb/IIIa and ADP receptors, but not aspirin-mediated inhibition of arachidonic acid, was found to decrease the onset and rate of thrombin generation in this experimental model
- Velik-Salchner C, Streif W, Innerhofer P, et al. Endotoxinemia-induced changes in coagulation as measured by rotation thrombelastometry technique and conventional laboratory tests: results of a pilot study on pigs. Blood Coagul Fibrinolysis 2009;20:41-46. An animal model of sepsis was used to examine the changes in hemostasis and functional coagulation measurements (RoTEM analysis) after administration of endotoxin. RoTEM analysis was able to show the early changes in coagulation after induction of endotoxinemia. A significant decrease in clot time, speed and quality of clot formation and fibrinogen/fibrin polymerization were all demonstrated, whereas no significant changes in the standard tests of coagulation or D-dimers were noted. These results suggest that TEG-y monitoring of patients at risk for developing sepsis might provide timely information regarding the progression of the septic state.
- Vila PM, Zafar MU, Badimon JJ. Platelet reactivity and nonresponse to dual antiplatelet therapy: a review. Platelets 2009;20(8):531-538. This review examines the phenomenon of platelet hyper-reactivity and the response to antiplatelet therapy. The general conclusions of the review are that there is a strong association between high platelet reactivity and the incidence of adverse outcomes, but the optimal level of platelet inhibition is still unknown.
- Warnaar N, Lisman T, Porte RJ. The two tales of coagulation in liver transplantation. Curr Opin Organ Transplant 2008;13:298-303. This is an excellent review article regarding the coagulopathy associated with cirrhotic liver disease. Examining hemostasis beyond the traditional PT and aPTT tests suggests that the hemostatic alterations observed are likely a matter of an imbalance between the procoagulant and anticoagulant pathways. Platelet abnormalities in liver disease are also discussed. Figure 1 provides a good overview of the concept of hemostatic balance.
- Wang JS, Lin CY, Hung WT, et al. Thromboelastogram fails to predict postoperative hemorrhage in cardiac patients. Ann Thorac Surg 1992;53:435-439. The results of this study demonstrated that neither RCTs nor TEG predicts the likelihood of excessive bleeding in patients after CPB.
- Welsby IJ, Jiao K, Ortel TL, et al. The kaolin-activated Thrombelastograph predicts bleeding after cardiac surgery. J Cardiothorac Vasc Anesth 2006;20:531-535. This prospective observational study of 30 cardiac patients found that kaolin activated TEG analysis reflects the severity of global coagulopathy that affects both platelets and coagulation factors and can guide prohemostatic therapy. The MA value was found to be a useful marker of generalized coagulopathy after cardiac surgery. The R-value was not correlated with bleeding. The results challenge the use of the kaolin activated R value as a guide for FFP replacement therapy. Univariate correlation analysis found that platelet counts and fibrinogen levels were most closely correlated with MA.
- White NJ, Martin EJ, Brophy DF, Ward KR. Coagulopathy and traumatic shock: Characterizing hemostatic function during the critical period prior to fluid resuscitation. Resuscitation 2010;81:111-116. Traumatic hemorrhagic shock was induced in a swine model. Changes in clot formation and clot structure and function were monitored using TEG analysis. In this experimental model of traumatic shock, fibrinogen was significantly reduced and an isolated reduction in clot strength (MA) was found with increasing blood loss. No significant changes in R, K, or angle were observed, suggesting that fibrinogen consumption and altered platelet function may account for the earliest changes in hemostatic function during traumatic shock. The possible mechanisms associated with the loss of fibrinogen were discussed.
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