[Thrombelastography: its use for the study of the fibrinolytic system].
Explore the source record for details and available documents.
Blood Coagulation Factors↗
SEARCH · Search PubMed
Results for “THROMBELASTOGRAPHY”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
[Long-term anticoagulant therapy in traumatology (surveillance by thrombelastography)].
Explore the source record for details and available documents.
Adult↗
The in vitro effects of crystalloids and colloids on coagulation.
Classically haemodilution is regarded as causing coagulopathy. However, haemodilution with saline seems to cause a hypercoagulable state both in vivo and in vitro. The aim of the present study was to measure the effect of mild to severe haemodilution using thrombelastography. Blood samples were taken in 12 healthy volunteers and divided into seven aliquots. One aliquot was undiluted and acted as control. The other six were diluted with normal saline, Ringer Acetate, 4% albumin, Dextran 70, 6% and 10% hydroxyethylstarch to 10%, 20%, 40%, 50% and 60% dilution. The dilution was checked by measuring the haemoglobin concentration. Each aliquot was placed in a temperature-controlled thrombelastography channel. Increased coagulation activity, as measured by thrombelastography changes, was detected at low and medium levels of dilution with all the tested solutions. At more than 40% dilution, coagulation returned to normal while in the case of dextran and hydroxyethylstarch coagulopathy developed. For crystalloids and albumin,dilution had to exceed 50% before coagulation was impaired. If these findings can be reproduced in vivo, they may have implications for transfusion practice and prophylaxis against thrombosis.
Blood Coagulation↗
Does arginine vasopressin influence the coagulation system in advanced vasodilatory shock with severe multiorgan dysfunction syndrome?
Arginine vasopressin (AVP) is a potent supplementary vasopressor in advanced vasodilatory shock, but decreases in platelet count have been reported during AVP therapy. In this study we evaluated the effects of AVP infusion on the coagulation system in advanced vasodilatory shock when compared to norepinephrine (NE) infusion alone. Forty-two patients with advanced vasodilatory shock (NE requirements >0.5 microg x kg(-1) x min(-1), mean arterial blood pressure <70 mm Hg) were prospectively randomized to receive an additional AVP infusion (4 U/h) or NE infusion alone. Most patients received coagulation active treatment (fresh-frozen plasma, thrombocyte concentrates, coagulation factors, and continuous veno-venous hemofiltration with heparin). At baseline and 1, 24, and 48 h after randomization, coagulation laboratory variables and a modified thrombelastography were measured. There were no differences between groups in plasmatic coagulation variables. Although there was no significant difference between groups, platelet count significantly decreased in AVP patients (P = 0.036). There were no differences in results of modified thrombelastography analyses between groups. AVP infusion in advanced vasodilatory shock with severe multiorgan dysfunction syndrome does not increase plasma concentrations of Factor VIII, von Willebrand Factor antigen, and ristocetin Co-Factor but may stimulate platelet aggregation and induce thrombocytopenia. Global coagulation, assessed by modified thrombelastography, is not different from patients receiving NE infusion alone.
Aged↗
Platelet function tests predict bleeding and thrombotic events after off-pump coronary bypass grafting.
OBJECTIVE: A balanced coagulation system after cardiac surgery minimizes bleeding and thrombotic events. However, the best method to monitor this balance has not been established. We used a series of tests of coagulation and platelet function to define the risk of bleeding and thrombotic events after OPCAB. METHODS: In 76 patients, routine coagulation tests (i.e. prothrombin time, fibrinogen level, d-dimer, and platelet count), thrombelastography, and whole blood aggregometry were obtained perioperatively and on days 1 and 3 after OPCAB. Intra- and postoperative blood loss was determined. Early patency of venous bypass grafts was determined using CT angiography (Philips Medical, Corp.). RESULTS: Chest tube output and red cell volume loss at 24 h were 952+/-475 and 190+/-115 ml, respectively. Early graft failure developed in eight patients. Perioperative changes in routine coagulation tests showed no correlation with either bleeding or thrombosis. However, perioperative decline in platelet function as assessed by the area under the impedance curve for whole blood aggregometry correlated with intraoperative blood loss (R=0.42, P<0.05). A perioperative decline in the maximum amplitude of the thrombelastography trace showed a significant correlation with 24h hemoglobin loss (R=0.45, P<0.05). Compared to those with all patent grafts, patients with early graft failure demonstrated a reduction in platelet sensitivity to aspirin by both thrombelastography and aggregometry on day 3. CONCLUSIONS: In contrast to standard coagulation testing, platelet function predicted both bleeding and thrombosis after OPCAB. Titration of perioperative platelet function according to these tests may minimize thrombosis without increasing bleeding.
Aged↗
Epsilon-aminocaproic acid for treatment of fibrinolysis during liver transplantation.
In 97 adult patients receiving liver transplants, the coagulation system was monitored by thrombelastography and by coagulation profile including PT; aPTT; platelet count; level of factors I, II, V, VII, VIII, IX, X, XI, and XII; fibrin degradation products; ethanol gel test; protamine gel test; and euglobulin lysis time. Preoperatively, fibrinolysis defined as a whole blood clot lysis index of less than 80% was present in 29 patients (29.9%), and a euglobulin lysis time of less than 1 h was present in 13 patients. Fibrinolysis increased progressively during surgery in 80 patients (82.5%) and was most severe on reperfusion of the graft liver in 33 patients (34%). When whole blood clot lysis (F less than 180 min) was observed during reperfusion of the graft liver, blood coagulability was tested by thrombelastography using both a blood sample treated in vitro with epsilon-aminocaproic acid (0.09%) and an untreated sample. Blood treated with epsilon-aminocaproic acid showed improved coagulation without fibrinolytic activity in all 74 tests. When whole blood clot lysis time was less than 120 min, generalized oozing occurred, and the effectiveness of epsilon-aminocaproic acid was demonstrated in vitro during the pre-anhepatic and post-anhepatic stages, epsilon-aminocaproic acid (1 g, single intravenous dose) was administered. In all 20 patients treated with epsilon-aminocaproic acid, fibrinolytic activity disappeared; whole blood clot lysis was not seen on thrombelastography during a 5-h observation period, and whole blood clot lysis index improved from 28.5 +/- 29.5% to 94.8 +/- 7.4% (mean +/- SD, P less than 0.001). None of the treated patients had hemorrhagic or thrombotic complications.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Nonlinear viscoelasticity and the thrombelastograph: 1. Studies on bovine plasma clots.
To study the possible role of nonlinear viscoelastic effects in the thrombelastograph (TEG), clotting of bovine plasma was studied by both thrombelastography and with a controlled strain rheometer. Clot rheology is dominated by elastic effects at frequencies of interest. There is a well-defined regime of linear elasticity for strains less than around 2%, while at larger strains the clots show significant strain hardening. Oscillatory shear applied during clotting has little effect on the resulting clot provided that the strain is less than 2%, but leads to substantial weakening of clots formed at larger strains. The TEG operates within the regime of nonlinear elasticity, significantly obscuring the interpretation of TEG amplitude in terms of an elastic modulus. Comparing the results of standard TEG experiments with those conducted with a modified TEG, having no oscillation during clotting, shows that deformation during standard thrombelastography leads to weaker clots than are produced under quiescent conditions.
Animals↗
Differential effects of serial hemodilution with hydroxyethyl starch, albumin, and 0.9% saline on whole blood coagulation.
STUDY OBJECTIVES: To determine by thrombelastography assessed coagulation, the effects of progressive hemodilution with three intravascular volume expanders. DESIGN: Prospective, controlled, whole blood, volumetric ex vivo hemodilution study. SETTING: University of Pennsylvania Medical Center Operating Rooms. PATIENTS: 60 ASA physical status I and II patients; phlebotomy prior to administration of IV fluids or medications. INTERVENTIONS: Analysis of whole blood clotting determined by six thrombelastographic channels for control and five volumetric hemodilutions (11%, 25%, 33%, 50%, and 75%) with 0.9% saline, 5% albumin, and 6% hydroxyethyl starch (n = 20 for each diluent group). MEASUREMENTS AND MAIN RESULTS: Thrombelastographic parameters R (minutes), angle alpha (degree), MA (mm), and lysis (%) were measured and compared to the sample control for each dilution of the same specimen. There was no significant difference between control groups in any thrombelastographic variable (R, angle alpha, MA, or lysis). No changes were seen in any variable from any diluent at 11% hemodilution. Seventy-five percent hemodilution caused significantly hypocoagulable changes from control for all thrombelastographic parameters for all three diluents. Thrombelastographic indices differed significantly from controls at intermediate hemodilutions. Both colloids caused decreases in measured angle alpha and MA at lower hemodilution than did 0.9% saline. Albumin 5% caused significant hypocoagulable changes from control values at lower hemodilution than did either 0.9% saline or 6% hydroxyethyl starch for all thrombelastographic parameters. Saline 0.9% increased angle alpha significantly at 50% hemodilution. Abnormal lysis did not occur at any dilution. Differing ex vivo effects of three different intravascular fluids thrombelastography assessed coagulation are found. CONCLUSION: No differences were found after 11% hemodilution with any volume expanders. Hemodilution with up to 50% saline maintained thrombelastographic indices. Albumin produced early and profound hypocoagulable effects. Significant hypocoagulability occurred for all three diluents at 75% hemodilution. The study supports the use of albumin in patients at risk for thrombosis, and saline in patients with a need for normal hemostasis.
Albumins↗
Platelet function testing in apheresis products: flow cytometric, resonance thrombographic (RTG) and rotational thrombelastographic (roTEG) analyses.
During storage of platelet concentrates, quality control of the units is mandatory. This includes the important testing of the hemostatic function of platelets. So far, mostly platelet aggregation analyses have been performed. In this study, new approaches were tested to evaluate the applicability of modern techniques for quality monitoring. Plateletpheresis was performed with two different cell separators (AMICUS cell separator, Fenwal, Baxter Healthcare, Deerfield, USA; COBE Spectra, COBE BCT, Lakewood, USA). In each procedure split products (n = 22) were prepared and stored for 1-2 days (n = 22) or 3 5 days (n = 22). Platelet hemostatic capacity was tested by applying flow cytometry. platelet aggregation (platelet-rich-plasma [PRP]+agonist), resonance thrombography (RTG; PRP, no agonist) and rotational thrombelastography (roTEG; PRP+agonist). Flow cytometric analyses did not reveal significant changes in structural (CD41a. CD42b) or activation-dependent antigens (CD62p, CD63, LIBS, RIBS). Also, differences in the data from the flow cytometric reactivity tests were not significant between the two groups. In platelet aggregation assays, shape change (p = 0.8), maximum aggregation (p = 0.4), and maximum gradient (p = 0.8) did not show significant differences between the two groups. In the RTG test, differences between r-time (reaction time; p = 0.4), and f-time (clot formation time [fibrin influence]; p = 0.3), and in roTEG r-time (coagulation time; p = 0.1) and k-time (clot formation time; p = 1.0) were not significant. P-time (clot formation time [platelet influence]) and M (maximum amplitude) in RTG, and k-time and MA (maximum amplitude) in roTEG showed a slight decrease in platelet function (p < or = 0.05). We conclude that platelet function is well maintained during storage. This is reflected by the results of immunological and platelet function assays. Rotational thrombelastography (in the case of PRP) and especially resonance thrombography represent promising methods for quality control of platelet concentrates and rapidly provide information about the status of platelet function and the whole clotting process.
Blood Coagulation Tests↗
Effect of progressive haemodilution with hydroxyethyl starch, gelatin and albumin on blood coagulation.
We have compared the effects of progressive (30% and 60%) in vitro haemodilution with hydroxyethyl starch (HES), gelatin (GEL) and albumin (ALB) with haemodilution using 0.9% saline in 96 patients by thrombelastography. Haemodilution with HES, GEL and ALB significantly (P < 0.05) compromised coagulation time (k), angle alpha and maximal amplitude (MA), with HES having the most negative effect at 30% and 60% haemodilution (P < 0.05). Haemodilution with saline significantly affected all variables of blood coagulation and clot lysis measured by thrombelastography, resulting in an increased coagulability at 30% haemodilution. To specifically assess the intrinsic effect of plasma expander molecules on blood coagulation and clot lysis, we analysed the difference between saline diluted blood (same degree of haemodilution) and plasma expander diluted blood. Prolongation of reaction time (r) was found for HES at 30% and 60% haemodilution and for ALB at 60% haemodilution and an increase in clot lysis by HES, GEL and ALB became evident. We conclude that HES, GEL and ALB compromised blood coagulation, while the maximum effect was found with HES.
Adolescent↗
Comparison of coagulation and blood loss during anaesthesia with inhaled isoflurane or intravenous propofol.
Propofol has been reported to affect blood coagulation. This prospective, randomized study compared coagulation and blood loss during anaesthetic maintenance with target-controlled intravenous propofol infusion vs. inhaled isoflurane. Thirty-eight ASA I-III patients undergoing head and neck surgery were allocated randomly to receive either inhaled isoflurane at end-tidal concentration 1-1.5% (group I, n=20) or target-controlled infusion (TCI) of propofol at target concentration 2-5 microg ml(-1) (group P, n=18). Thrombelastography on recalcified whole blood was performed pre-induction, and at 15, 30, 60, 90, 120 min post-induction and 30 min after anaesthesia in both groups. Blood loss was estimated from weighing swabs and the volume in suction bottles. Induced hypotension was not used, and perioperative body temperature was similar between groups. There were no significant differences in thrombelastographic coagulation (R-time, K-time, maximum amplitude and angle) or fibrinolytic variables (lysis index at 30 and 60 min) at all times between groups. Total blood loss was also not significantly different (median group I: 350 ml, range 20-1200 ml; group P: 200 ml, range 50-800 ml). Shortening of R-time and widening of angle developed over time in both groups (P<0.05 groups I and P, repeated measures ANOVA). We conclude that maintenance of anaesthesia with propofol TCI at 2-5 microg ml(-1) does not cause detectable coagulation changes on thrombelastography nor increase surgical blood loss when compared to inhaled isoflurane.
Adult↗
Endogenous heparin-like substances significantly impair coagulation in patients undergoing orthotopic liver transplantation.
UNLABELLED: Orthotopic liver transplantation (OLT) is associated with severe bleeding, especially after reperfusion of the grafted liver. Heparin released from the liver graft contributes to postreperfusion coagulopathy. Although patients with liver cirrhosis have increased levels of endogenous heparinoids, the role of these substances during liver transplantation is unclear. Therefore, we performed native and heparinase-modified thrombelastography (TEG) in 72 patients undergoing OLT. TEG was performed at skin incision, 10 min before and 10 min after clamping of the vena cava, 10 min before and 10 min after graft perfusion, and at the end of surgery. Heparinase-modified TEG compared with native TEG demonstrated heparin activity. In contrast to other investigations, we found significant heparin effects before reperfusion, although patients received no exogenous heparin. These heparin effects were greater in patients with cirrhosis compared with patients with cancer as the underlying disease leading to OLT. Administration of coagulation factors is the usual treatment of coagulopathies during OLT. The comparison of native versus heparinase-modified TEG can distinguish between heparin activity or coagulation factor deficiency as a cause of bleeding complications and provides a rational approach to the treatment of bleeding during OLT. IMPLICATIONS: Impaired coagulation function, contributed to by heparin or heparin-like substances, is frequently observed after reperfusion of a transplanted liver. This study demonstrates that a heparinase-modified thrombelastography can identify significant heparin effects in the absence of exogenous heparin administration in patients undergoing liver transplantation.
Anticoagulants↗
Are lactated Ringer's solution and normal saline solution equal with regard to coagulation?
UNLABELLED: Crystalloids represent an attractive strategy to alleviate intravascular volume deficits. Crystalloid hemodilution was associated with hypercoagulability in in vitro and in vivo studies. The influence of different crystalloids on coagulation in the surgical patient is not well studied. In a prospective, randomized study in patients undergoing major abdominal surgery, we used either lactated Ringer's solution (RL) (n = 21) or 0.9% saline solution (SS) (n = 21) exclusively for intravascular volume replacement over 48 h to maintain central venous pressure between 8 and 12 mm Hg. Activated thrombelastography (TEG) using different activators (intrinsic TEG, extrinsic TEG, heparinase TEG, aprotinin TEG) was used to measure coagulation time, clot formation time, and maximum clot firmness. Measurements were performed after induction of anesthesia (T0), immediately after surgery (T1), 5 h after surgery (T2), and on the morning of the first (T3) and second (T4) postoperative days. RL 18,750 +/- 1890 mL and 17,990 +/- 1790 mL of SS were infused during the study period. Acidosis was seen only in the SS-treated group. Blood loss was not different between the groups. Fibrinogen and antithrombin III decreased similarly at T1 and T2 in both groups, most likely because of hemodilution. Differences in TEG data from normal baseline were seen only immediately after surgery and 5 h thereafter, indicating mild hypercoagulability in the intrinsic TEG (RL, from 147 +/- 130 s to 130 +/- 11 s; SS, from 146 +/- 12 s to 131 +/- 12 s). There were no differences in coagulation between RL- and SS-treated patients. We conclude that in major abdominal surgery intravascular volume replacement with crystalloids resulted in only moderate and abbreviated changes in coagulation. No differences in activated TEG and blood loss were seen between an RL- and an SS-based intravascular volume replacement regimen. IMPLICATIONS: In 42 patients undergoing major abdominal surgery, either lactated Ringer's solution or 0.9% saline solution were exclusively used for volume therapy for 48 h. Activated thrombelastography revealed some mild hypercoagulability after surgery. No differences in coagulation were seen between the two intravascular volume replacement strategies.
Abdomen↗
The predictive value of modified computerized thromboelastography and platelet function analysis for postoperative blood loss in routine cardiac surgery.
UNLABELLED: Hemorrhage after cardiopulmonary bypass (CPB) remains a clinical problem. Point-of-care tests to identify hemostatic disturbances at the bedside are desirable. In the present study, we evaluated the predictive value of two point-of-care tests on postoperative bleeding after routine cardiac surgery. Prospectively, 255 consecutive patients were studied to compare the ability of modified thromboelastography (ROTEG) as well as a platelet function analyzer (PFA-100) to predict postoperative blood loss. Measurements were performed at three time points: preoperatively, during CPB, and after protamine administration with three modified thromboelastography and PFA tests. The best predictors of increased bleeding tendency were the tests performed after CPB. The angle alpha is the best predictor (area under the receiver operating characteristic curve 0.69) and, in combination with the adenosine diphosphate-PFA test, the predictive accuracy is enhanced (area under the receiver operating characteristic curve 0.73). The negative predictive value for the angle alpha is 82%, although the positive predictive value is small (41%). Thromboelastography is a better predictor than PFA. In routine cardiac surgery, impaired hemostasis as identified by point-of-care tests does not inevitably lead to hemorrhage postoperatively. However, patients with normal test results are unlikely to bleed for hemostatic reasons. Bleeding in these patients is probably caused surgically. The high negative predictive value supports early identification and targeted treatment of surgical bleeding by distinguishing it from a significant coagulopathy. IMPLICATIONS: Thrombelastography and platelet function analysis in routine cardiac surgery demonstrate high negative predictive values for postoperative bleeding, which supports early identification and targeted treatment of surgical bleeding by distinguishing it from a significant coagulopathy. The positive predictive values are small. The best predictors are thrombelastography values obtained after cardiopulmonary bypass.
Aged↗
Hemodilution with lactated Ringer's solution causes hypocoagulability in rabbits.
Hemodilution (HD) has been associated with hypercoagulability. It was hypothesized that HD with lactated Ringer's solution (LR) would result in hypercoagulability in rabbits. Sedated rabbits (n = 12) underwent HD with LR (40% estimated blood volume replaced with five volumes of LR) via ear vessels. Key procoagulants and anticoagulant activities were assessed prior to and 3 h after HD. Hemostatic function was assessed with the activated coagulation time and platelet-inhibited thrombelastography. Circulating tissue factor activity was much more diluted (-67.2% from baseline) than tissue factor pathway inhibitor (-45.2%) or antithrombin (-9.5%) activities after HD. HD significantly decreased factor VIII complex activity (-31.5%) more than protein C activity (-5.9%), and factor X activity (-29.2%) was more diluted than antithrombin activity. The activated coagulation time and thrombelastography demonstrated a significant decrease in hemostatic function after HD. Hemodilution with LR caused hypocoagulability in the rabbit. A greater decrease in circulating procoagulant activity than anticoagulant activity appears to be the mechanism underlying HD-mediated decreases in hemostasis.
Animals↗
Coagulation changes and edema formation during long-distance bus travel.
Long-distance travel in a cramped position by aircraft or by bus and car has been suggested to be associated with an increased risk for thromboembolic events. Recently, we demonstrated moderate activation of coagulation after a long-haul flight. At present the single contributing factors (i.e. hypoxia and low humidity on board an aircraft and prolonged sitting in an aircraft, car or bus inducing venous stasis) have not yet been investigated. Therefore we measured markers of coagulation and fibrinolysis as well as functional parameters of coagulation using activated thrombelastography in 19 healthy volunteers before, during and after a real 10-h bus journey. In addition, changes in leg volume were measured. Thrombelastography revealed moderate activation of coagulation in all travelers, which was accompanied by a significant increase in prothrombin fragment F1 + 2. Thrombin-antithrombin III complexes and D-dimer remained unchanged, and tissue-type plasminogen activator and plasminogen-activator inhibitor 1 decreased after travel. After the travel we found a significant increase in leg volume that was exclusively distributed in the calf. We conclude that beside long-haul flights also long-distance bus travel induces a certain activation of the coagulation system. Thus, it is questionable whether hypoxia is the crucial risk factor for thromboembolic events after long-haul flights.
Aircraft↗
Quantification of the effects of thrombin activatable fibrinolysis inhibitor and alpha2-antiplasmin on fibrinolysis in normal human plasma.
Two major proteins that inhibit fibrinolysis include thrombin activatable fibrinolysis inhibitor (TAFI) and alpha2-antiplasmin. Our goal was to quantify the contribution of TAFI and alpha2-antiplasmin to antifibrinolytic defenses with thrombelastography. Plasma activated with tissue factor/kaolin was subjected to fibrinolysis with tissue-type plasminogen activator (100 U/ml). Prior to activation, TAFI activity was inhibited with either potato carboxypeptidase inhibitor (25 microg/ml) or an anti-TAFI antibody, and alpha2-antiplasmin activity was inhibited with an anti-alpha2-antiplasmin antibody. Data were collected for 30 min, with the time of onset and rate of fibrinolysis determined. Compared with uninhibited samples, TAFI inhibition significantly (P < 0.05) decreased the time of onset of fibrinolysis by 70% and increased the rate of lysis by 70%. There was no difference between potato carboxypeptidase inhibitor and anti-TAFI antibody inhibition. Inhibition of alpha2-antiplasmin resulted in a significantly (P < 0.05) decreased time of onset (85%) and increased the rate of lysis (557%) compared with uninhibited samples. Inhibition of alpha2-antiplasmin activity resulted in a significantly (P < 0.05) greater fibrinolytic response than TAFI inhibition. In conclusion, utilization of standard inhibitors and thrombelastography permitted quantification of the effects of TAFI and alpha2-antiplasmin on fibrinolysis in plasma. Future investigation of diseases involving hypofibrinolysis (e.g. left ventricular assist devices) could be conducted using this assay system.
Antibodies↗
The effect of low-dose heparin on hypercoagulability following abdominal aortic surgery.
The effect of low-dose heparin on postoperative hypercoagulability was assessed using thrombelastography (TEG) in eighteen patients undergoing elective abdominal aortic surgery. Patients received unfractionated heparin 5000IU bd SC commencing on the first postoperative day. Native whole blood TEG was performed preoperatively and on day two postoperatively. A heparinase-modified TEG was performed at the same time as the native whole blood TEG on day two. There were no significant changes in the postoperative native whole blood TEG variables (r, K, alpha, MA) relative to preoperative controls. In contrast, there were significant decreases in r and K, and increases in alpha in the heparinase-modified TEGs postoperatively (P < 0.01). There were significant differences between the postoperative native whole blood and heparinase-modified TEGs for all TEG variables (P < 0.01). The results indicate that low-dose heparin reduces postoperative hypercoagulability following abdominal aortic surgery as assessed by thrombelastography.
Aged↗