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PubMed1996

The effect of aprotinin on thrombelastography in vitro.

The effect of low dose (50 KIU/ml) and high dose (200 KIU/ml) aprotinin on standard thrombelastographic variables (r, K, alpha, MA) was examined in vitro using blood from forty ASA Class 1 patients. Both concentrations of aprotinin resulted in minor increases in r time above the normal range (P < 0.05). Aprotinin did not alter other thrombelastographic variables. The results indicate that aprotinin is a mild direct anticoagulant in vitro as assessed by thrombelastography.

Adolescent↗
PubMed2004

Electron microscopic evaluations of clot morphology during thrombelastography.

In this study, we characterized clot morphology with a scanning electron microscope (SEM) at time points corresponding to the commonly used thrombelastography (TEG) variables, illustrating the correlation of the physical clot formation with TEG(R) tracings. The first channel of the TEG analyzer was used to obtain the tracings of clot formation, while the sub-samples for the SEM were obtained from the second TEG channel. Different types of samples were examined, including whole blood, abciximab-treated whole blood, platelet-rich plasma (PRP), and abciximab-treated PRP. The SEM images were obtained at reaction time, different amplitudes (5-30 mm), maximum amplitude (MA), and at amplitude 60 min after MA. In the whole blood, coarse fibrin and activated platelets were observed at reaction time and fibrin strands progressively became more solid and intertwined at amplitude 10 mm and thereafter. Red blood cells were surrounded with fibrin strands at amplitude 30 mm and were tightly packed by fibrin strands at MA. In abciximab-treated whole blood, red blood cell shape was maintained at MA. The process of fibrin formation and platelet activation was also examined in PRP. Abciximab did not block platelet shape change, although the blockage of fibrin binding to platelets was shown on the TEG analyzer. In summary, we have shown structural changes of the forming clot in relation to TEG variables.

Abciximab↗
PubMed2004

The effect of dilution on plasma coagulation kinetics determined by thrombelastography is dependent on antithrombin activity and mode of activation.

Hemodilution-associated hypercoagulability has been the focus of several investigations because significant morbidity and mortality have been associated with perioperative thrombophilia. Because most investigations implicate imbalances in procoagulant/anticoagulant activity as the etiology of hemodilution-associated hypercoagulability, we determined the effects of dilution on coagulation kinetics and clot strength with thrombelastography (TEG(R)). Control plasma (+/-celite activation) and antithrombin (AT)-deficient (<10% activity) plasma were diluted 0%, 10%, 20%, and 30% with saline. TEG(R) variables measured included time to clot initiation (reaction time, R), speed of clot propagation (angle, alpha), and clot strength (amplitude, A; or shear elastic modulus, G). Dilution of control plasma (10%-30%) resulted in a significant (P < 0.05) 16% decrease in R values, no change in alpha values, and decrease in A and G values. AT-deficient plasma had significantly smaller R values compared with control, and dilution did not change R values in AT-deficient plasma. Celite activation eliminated dilution-associated changes in R values in control plasma but resulted in linear decreases (R(2) = 0.88-0.96, P < 0.0001) in alpha, A, and G in response to dilution. Thus, our data indirectly support the concept that decreases in AT activity cause dilution-mediated hypercoagulability in plasma. Finally, celite activation permits quantification of dilution with TEG.

Antithrombins↗
PubMed2005

The effects of platelet count on clot retraction and tissue plasminogen activator-induced fibrinolysis on thrombelastography.

Clot retraction and fibrinolysis may present as a decrease in amplitude on thrombelastography (TEG). The former represents normal or hyperactive platelet function, and the latter represents a fibrinolytic state. It is important to distinguish clot retraction from fibrinolysis because the treatment of each condition is different. To distinguish between these phenomena, we performed TEG with platelet-poor plasma (PPP) and platelet-rich plasma (PRP) with an increasing platelet count (range, 50-1200 x 10(9)/L) with or without abciximab. Maximum amplitude (MA) and the percentage decrease of amplitude at 30 and 60 min after MA were examined for each sample. Blood samples to which tissue plasminogen activator (tPA) was added served as positive controls for fibrinolysis. Morphological changes of clots and D-dimer levels were also examined. With higher platelet counts, the percentage decrease of amplitude after MA increased significantly at 30 and 60 min, but not in the abciximab samples. Morphological changes of clots have shown clot retraction in PRP, but not in PPP or PRP pretreated with abciximab. D-dimer levels increased only in samples to which tPA was added, but not in native PPP or PRP samples. In conclusion, we have shown that the decrease in amplitude at 30 and 60 min can be due to platelet-mediated clot retraction and can be attenuated by sample pretreatment with abciximab, which interrupts platelet-fibrin(ogen) binding.

Abciximab↗
PubMed2006

The impact of tissue factor pathway inhibitor on coagulation kinetics determined by thrombelastography.

BACKGROUND: Tissue factor pathway inhibitor (TFPI) is a 40-kDa, endogenous protein that inhibits tissue factor (TF)-initiated coagulation by bonding with activated factor X (FXa). The TFPI/FXa complex then subsequently binds with TF/activated factor VII (FVIIa) complex, ultimately inhibiting thrombin generation. Heparin administration causes endothelial release of TFPI concentrations up to sixfold normal values. Thrombelastography (TEG) is often used to monitor hemostasis in the perioperative period, and TFPI could potentially affect the diagnostic interpretation of TEG-based data, given its inhibition of both common and TF coagulation pathways. Thus, in this study we characterized the effect of TFPI on coagulation kinetics via TEG. METHODS: Whole blood, Factor VII-deficient plasma, and normal plasma were exposed in vitro to various concentrations of TFPI, after which unmodified, celite-activated, and TF-activated TEG were performed. RESULTS: The addition of 87.5 ng/mL TFPI (twice normal concentration) was required to prolong clot propagation in whole blood, with propagation and strength only significantly affected by the addition of 175 ng/mL concentrations. Experiments with Factor VII-deficient plasma demonstrated that TFPI-mediated suppression of coagulation kinetics at these concentrations was secondary to FXa inhibition. Celite activation markedly attenuated TFPI-mediated effects on coagulation kinetics, whereas TF activation accentuated TFPI-mediated prolongation of clot initiation and diminution of propagation. CONCLUSIONS: In settings involving heparin administration (e.g., cardiopulmonary bypass), TFPI-mediated inhibition of coagulation should be considered during TEG-based hemostatic monitoring.

Blood Coagulation↗
PubMed1986

Procoagulant activity and thrombelastography in Korean hemorrhagic fever.

Twenty male patients with Korean hemorrhagic fever were evaluated with thrombelastography (TEG) to assess the changes in coagulation system, and the results were compared with those of conventional coagulation tests. Procoagulant activity in the plasma was determined by comparing the reaction time "r" of the normal plasma and that of the mixture of equal parts of the normal plasma and the patient's plasma. The TEG was found to be a useful measure of the changes in the coagulation profile, and provided instant accurate assessment of the patient's hemostatic function. Presence of the procoagulant activity was demonstrated in the plasma of the patients and indicated occurrence of active intravascular coagulation during the early stage of the disease.

Adult↗
PubMed2003

Thrombelastography. Present and future perspectives in clinical practice.

RESULTS: Thrombelastography (TEG) is a method for evaluating the viscoelastic properties of the blood clot, from its formation to its lysis. All major surgeries may be associated with massive blood loss, with blood component transfusion therapy often becoming mandatory. The clinician's goal is thus to optimize and possibly minimize blood components usage. To this end, TEG allows for a qualitative and dynamic analysis of the specific blood clotting process, from clot formation through its lysis, highlighting alterations at every single step in the cascade. With TEG is thus possible to know if bleeding is due to a failure to provide adequate surgical hemostasis, if there is platelet dysfunction, or to detect anomalies in coagulation proteases or their inhibitors, or if the blood loss is associated to early, excessive fibrinolysis. The theoretical advantages of TEG are the ease of performing the test, the fast sample reading times (now 30 minutes) and the informative

Blood Coagulation↗
PubMed1992

[Thrombelastography as a bedside monitor of coagulation and fibrinolysis during surgery--a report of three cases].

Three patients with abnormal hemostasis during surgery were reported. They were monitored by thrombelastography (TEG). The first case was a 48 year old male who underwent extravivo hepatectomy. TEG showed hypo-coagulability during anhepatic phase. After reperfusion to the liver, the coagulability determined by TEG returned to a normal pattern. The second patient was a 32 year old female who underwent laparotomy to stop bleeding for cervico-vaginal laceration after delivery. The patient had been in severe hemorrhagic shock, and massive blood transfusion and fluid administration were performed. TEG showed remarkable hypocoagulability probably due to blood dilution and consumption coagulopathy. When TEG returned to a normal pattern after administration of fresh frozen plasma and fresh whole blood, the abnormal bleeding stopped. The third patient was a 48 year old male who underwent resection of metastatic brain tumor. He had hepatocellular carcinoma and liver cirrhosis. During surgery, abnormal bleeding was seen at surgical field, when TEG revealed remarkable hyper-fibrinolysis. After antifibrinolytic therapy coupled with replacement therapy, TEG returned to a normal pattern and the abnormal bleeding ceased. We conclude that TEG is a useful bed side monitor for the diagnosis of coagulopathy and hyper-fibrinolysis during surgery.

Adult↗
PubMed1992

[Effects of induced hypotensive anesthesia on the blood coagulation-fibrinolysis system measured by thrombelastography--comparison between prostaglandin E1 and trimethaphan].

The coagulation-fibrinolysis system has been studied in two groups of 16 patients classified ASA 1 undergoing radical mastectomy during controlled hypotensive anesthesia induced by prostaglandin E1 (PGE1) or by trimethaphan (TMP) under enflurane anesthesia. Thrombelastography (TEG) was used to evaluate both coagulation and fibrinolysis systems, while simultaneously measuring platelet aggregation in response to ADP and collagen, prothrombin time (PT), activated partial thromboplastin time (APTT), serum concentrations of fibrinogen, and platelet counts. In the PGE1 group, APTT was significantly shortened (P less than 0.05) while the drug was being infused, but there was no statistically significant difference between the two groups, which was considered due to the effect of enflurane. Also, no statistically significant changes were noted in the other measured parameters. These results suggest that controlled hypotensive anesthesia using either PGE1 or TMP under enflurane anesthesia produces no significant changes in the blood coagulation-fibrinolysis system and that both are useful for the management of bleeding during surgery. Further, TEG was found to reflect other parameters properly. It is therefore useful for monitoring the blood coagulation-fibrinolysis system during anesthesia.

Adult↗
PubMedDate not supplied

Thrombelastography as an aid to regional anesthesia: preliminary communication.

Thrombelastography (TEG), a less commonly available technique used to assess hemostatic function, has recently gained popularity. Analysis of TEG yields qualitative information about platelet function, thromboplastin generation and their interaction with the intrinsic cascade to form a stable clot. Additional information is obtained about fibrinogen and Factor XIII levels as well as the fibrinolytic system. TEG has been shown to be more sensitive and accurate than traditional coagulation tests at both predicting and treating coagulopathies. We report here three cases in which TEG was used to assess hemostatic function in patients at risk for bleeding prior to the induction of regional anesthesia. In all three cases, traditional tests were inadequate to predict the safe practice of regional anesthesia. TEG provided this information and regional anesthesia was successfully employed.

Aged↗
PubMed1978

Thrombelastography during and after elective abdominal surgery.

Thrombelastography has been performed on recalcified whole blood from 50 patients before, during and after elective abdominal surgery. The characteristic changes of the thrombelastographic indices r, k and mA are described. During operation r and k shortened, but no change in mA was observed. This response was in part associated with an increase in factor VIII activity. Following operation, while r time was somewhat shortened, much more marked changes in k and mA were evident. Increasing fibrinogen concentration was the dominant factor in determining the post-operative changes in the thrombelastograph.

Abdomen↗
PubMed1980

Characterization of a new potent heparin. 3rd Communication: Determinations of anticoagulant activity of a new potent heparin preparation by thrombelastography in vitro using citrated dog and human blood.

The anticoagulant effect of a new potent heparin preparation was compared with a commercially available heparin by thrombelastography in vitro using citrated dog and human blood. The relative potency of the new heparin was found to be 1.45 to 1.77 with dog citrated blood and 1.77 to 2.41 with human citrated blood on the basis of different thrombelastographic parameters.

Animals↗
PubMed1981

Comparison of thrombelastography with common coagulation tests.

Thrombelastography, although proven as a useful research tool has not been evaluated for its clinical utility against common coagulation laboratory tests. In this study we compare the thrombelastographic measurements with six common tests (the hematocrit, platelet count, fibrinogen, prothrombin time, activated thromboplastin time and fibrin split products). For such comparisons, two samples of subjects were selected, 141 normal volunteers and 121 patients with cancer. The data was subjected to various statistical techniques such as correlation, ANOVA, canonical and discriminant analysis to measure the extent of the correlations between the two sets of variables and their relative strength to detect blood clotting abnormalities. The results indicate that, although there is a strong relationship between the thrombelastographic variables and these common laboratory tests, the thrombelastographic variables contain additional information on the hemostatic process.

Blood Coagulation Disorders↗
PubMed1996

[Blood coagulation-fibrinolysis system during transurethral resection evaluated by thrombelastography].

Intraoperative changes in blood coagulation-fibrinolysis system were evaluated in 21 patients under epidural anesthesia by thrombelastography. Ten patients received transurethral resection of prostate (TUR-P) and 11 patients received transurethral resection of bladder tumor (TUR-Bt). Thrombelastographic variables: reaction time (R), coagulation time (K), maximum amplitude (MA), and amplitude 60 min after MA (A 60) were measured. The coagulability was evaluated by R + K, the absolute strength of clot by MA, and fibrinolysis using MA-A60. There was no significant change of these indices in TUR-Bt group. On the other hand, in TUR-P group, R + K was significantly shortened and MA-A60 had a tendency to increase it, but MA caused no change. Resected prostatic weight correlated significantly with the decrease of MA, and had a tendency to correlate with the increase of MA-A60 in TUR-P group. Both coagulation and fibrinolysis were activated in TUR-P group. When the resected prostatic weight is large, the risk of coagulopathy may increase.

Anesthesia, Epidural↗
PubMed1994

Abruptio placentae and disseminated intravascular coagulation: use of thrombelastography and sonoclot analysis.

We report a case in which thrombelastography (TEG) and Sonoclot analysis were used for diagnosis and treatment decisions in a patient with abruptio placentae and disseminated intravascular coagulation. In addition to providing enough information for evaluation and treatment of this patient, the TEG and Sonoclot results were obtained more quickly, with smaller blood samples and with less expense to the patient in comparison to the standard coagulation tests in our institution. Although the TEG and Sonoclot results were assessed independently of the other test and each provided similar information in this case, the TEG may be the preferred tool in evaluating coagulopathies, based on computerization and strong literature support.

Journal Article↗
PubMed1999

Vascular surgical society of great britain and ireland: thrombelastography can differentiate ischaemic from haemorrhagic stroke

BACKGROUND: Thrombolysis could be a major step forward in the treatment of acute ischaemic stroke. Early treatment is essential to maximize therapeutic benefit. Imaging by computed tomography (CT) or magnetic resonance imaging is mandatory to exclude haemorrhagic stroke before initiation of therapy. Thrombelastography (TEG), a test of global haemostasis, produces a characteristic tracing over 15-30 min. The potential of TEG to differentiate patients with ischaemic from haemorrhagic stroke was investigated. METHODS: Fifteen patients with a clinical diagnosis of acute stroke were studied. Fibrinogen levels and lipid profiles were measured, and CT of the brain, coagulation screens and TEG were performed. The CT scans were interpreted by a single radiologist. TEG data were classified as normal (index less than 2), hypercoagulable (index 2-3) or profoundly hypercoagulable (index greater than 3). RESULTS: There was no correlation between any of the parameters studied other than TEG with CT findings. Both patients with a haemorrhagic stroke showed normal findings on TEG. Eleven of the 12 patients with ischaemic stroke were hypercoagulable or profoundly hypercoagulable. CONCLUSION: TEG is capable of differentiating haemorrhagic from ischaemic stroke. It has the potential to target thrombolytic therapy for those patients most likely to benefit.

Journal Article↗