Thromboelastography Maximum Amplitude Research Articles

Early Online.

Long-haul flights have been associated with a two- to four-fold increased risk of aviation-related thrombosis (ART). Several studies have investigated the extent to which hypoxic hypobaric exposure, dehydration and prolonged immobilisation during air travel induce changes in haemostasis. To investigate the role of high altitude as a risk factor for ART. Healthy volunteers aged ≥18 years (N=40), without risk factors for venous thromboembolism, were exposed to an exacerbated altitude of 18 000 feet (5 486 m) for 1 hour. During the flight, the oxygen (O2) levels of the participants, who received supplemental O2, were measured by pulse oximetry and maintained at >92%. Venous blood and urine samples were collected prior to departure and immediately after flying in an unpressurised twin-engine airplane. D-dimer levels, thromboelastography (TEG) parameters, von Willebrand factor (VWF) activity and urine osmolality were measured. The participants were 19 men and 21 women, with a mean (standard deviation) age of 46 (14) years. A significant difference in D-dimer levels, VWF activity, urine osmolality and TEG parameters (reaction (R) time, kinetic (K) time and maximum amplitude (MA)) before and after the 1-hour flight was observed (p<0.001). Urine osmolality correlated positively with VWF activity levels (r=0.469; p<0.002). Air travel at high altitude induced a hypercoagulable state in healthy volunteers. Future research should focus on whether thromboprophylaxis can significantly obviate the activation of coagulation in response to high altitude.

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

To compare standard tests of haemostasis in hypercoagulable and normocoagulable sick dogs as identified by thromboelastography. We compared prothrombin time, activated partial thromboplastin time, D-dimers, packed red blood cell volume and platelet counts in client-owned sick dogs with hypercoagulable (n = 36) and normocoagulable (n = 35) states as identified by thromboelastography maximum amplitude above or within the established reference interval, respectively. Seventy-one dogs were included. Thirty-six dogs were hypercoagulable and 35 were normocoagulable on thromboelastography. Using multivariable linear models, prothrombin time, activated partial thromboplastin time and D-dimers were not associated with hypercoagulability. Platelet counts and packed red blood cell volume were significantly associated with hypercoagulability. Prothrombin time, activated partial thromboplastin time and D-dimers were not useful in the identification of hypercoagulability in dogs as defined by thromboelastography.

Safe and Effective Blood Preservation Through Acute Normovolemic Hemodilution and Low-Dose Tranexamic Acid in Open Partial Hepatectomy.

In this study, we evaluated the efficacy of tranexamic acid (TXA) and acute normovolemic hemodilution (ANH) with 6% hydroxyethyl starch (130/0.4) in minimizing blood loss during open partial liver resection. Coagulation function was assessed using thromboelastography (TEG) and hemostasis tests, while renal function changes were tracked through serum creatinine values post-surgery. Thirty patients undergoing open partial liver resection were allocated to two groups: Group T received TXA + ANH, and Group A received ANH alone. Blood was drawn from the radial artery under general anesthesia. Both groups received peripheral vein injections of 6% hydroxyethyl starch 130/0.4. Group T additionally received intravenous TXA. Primary outcomes included blood loss and allogeneic blood transfusions. TEG assessed coagulation status and renal function was monitored. Group T demonstrated superior outcomes compared to Group A. Group T had significantly lower intraoperative blood loss (700 mL vs 1200 mL) and a lower bleeding rate per kilogram of body weight (13.3 mL/kg vs 20.4 mL/kg). Coagulation parameters favored Group T, with higher TEG maximum amplitude (55.91 mm vs 45.88 mm) and lower activated partial thromboplastin time (38.04 seconds vs 41.49 seconds). Neither group experienced acute renal injury or kidney function deficiency during hospitalization. TXA and ANH in a small dose during liver resection stabilize clotting, reduce blood loss by 6% compared to hydroxyethyl starch 130/0.4, and do not affect renal function.

Thromboelastography and Traditional Coagulation Testing in Non-ICU-Admitted Patients with Acute Kidney Injury: An Observational Cohort Study

Introduction: This study aimed to elucidate the coagulation disorders in non-ICU patients with acute kidney injury (AKI) and their contribution to clotting-related outcomes of intermittent kidney replacement therapy (KRT). Methods: We included non-ICU-admitted patients with AKI requiring intermittent KRT, clinically having a risk of bleeding and against systemic anticoagulant use during KRT between April and December 2018. The premature termination of treatment due to circuit clotting was considered a poor outcome. We analyzed the characteristics of thromboelastography (TEG)-derived and traditional coagulation parameters and explored the potential-affecting factors. Results: In total, 64 patients were enrolled. Hypocoagulability was detected in 4.7%–15.6% of patients by a combination of the traditional parameters, i.e., prothrombin time (PT)/international normalized ratio, activated partial PT, and fibrinogen. No patient had hypocoagulability observed on TEG-derived reaction time; only 2.1%, 3.1%, and 10.9% of patients had hypocoagulability on TEG-derived kinetic time (K-time), α-angle, and maximum amplitude (MA), respectively, which were also platelet-related coagulation parameters, despite 37.5% of the cohort having thrombocytopenia. In contrast, hypercoagulability was more prevalent, involving 12.5%, 43.8%, 21.9%, and 48.4% of patients on TEG K-time, α-angle, MA, and coagulation index (CI), respectively, although thrombocytosis was only in 1.5% of the cohort. Patients with thrombocytopenia showed lower fibrinogen level (2.6 vs. 4.0 g/L, p = 0.00), α-angle (63.5° vs. 73.3°, p = 0.00), MA (53.5 vs. 66.1 mm, p = 0.00), and CI (1.8 vs. 3.6, p = 0.00) but higher thrombin time (17.8 vs. 16.2 s, p = 0.00) and K-time (2.0 vs. 1.2 min, p = 0.00) than those with a platelet count over 100 × 10⁹/L. 41 patients were treated with heparin-free protocol, and 23 were treated with regional citrate anticoagulation (RCA). The premature termination rate was 41.5% on heparin-free patients, while 8.7% of patients underwent an RCA protocol (p = 0.006). Heparin-free protocol was the strongest adverse factor to poor outcomes. A heparin-free subgroup analysis found that the circuit clotting risk was increased by 61.7% with a 10 × 10⁹/L elevation in platelet count (odds ratio [OR] = 1.617, p = 0.049) and decreased by 67.5% following a second increase of PT (OR = 0.325, p = 0.041). No significant correlation was found between TEG parameters and premature circuit clotting. Conclusions: Most non-ICU-admitted patients with AKI had normal-to-enhanced hemostasis and activated platelet function based on TEG results, as well as a high rate of premature circuit clotting when receiving heparin-free protocol despite thrombocytopenia. Further studies are needed to better determine the use of TEG in respect to management of anticoagulation and bleeding complications in AKI patients with KRT.

Interaction Between Platelet and Fibrinogen on Clot Strength in Healthy Patients

The purpose of this study was to explore the relationship between platelet concentration (PLT) (× 109/L) and clot strength measured by thromboelastography maximum amplitude (TEG-MA) in healthy volunteers without a history of coagulation abnormalities. Secondarily, the relationship between fibrinogen (mg/dL) and TEG-MA was analyzed. A prospective study. At a university's tertiary-care center. Using whole blood, PLT was reduced in the first part, and hematocrit was reduced in the second part of the study by hemodilution with platelet-rich and -poor plasma. Thromboelastography (TEG 5000 Haemonetics) was performed to measure clot formation and strength. Spearman correlation coefficients regression analyses and receiver-operating characteristics (ROC) were obtained to analyze the relationships among PLT, fibrinogen, and TEG-MA. Strong correlations were found in univariate analysis between PLT and TEG-MA (r=0.88; p < 0.0001) and between Fibrinogen and TEG-MA (r=0.70; p=0.003). A biphasic relationship between PLT and TEG-MA was linear below a PLT 90×109/L, followed by a plateau above 100×109/L (p=0.001). A linear relationship between fibrinogen (190-474 mg/dL) and TEG-MA (53-76 mm) was found (p=0.0007). The ROC analysis found that PLT=60×109/L was associated with a TEG-MA of 53.0 mm. The product of PLT and fibrinogen concentrations was more strongly correlated (r=0.91) to TEG-MA than either PLT (r=0.86) or fibrinogen (r=0.71) alone. A ROC analysis revealed that a TEG-MA of 55 mm was associated with a PLT×fibrinogen of 16,720. In healthy patients, a PLT of 60×109/L was associated with normal clot strength (TEG-MA ≥53 mm), and there was little change in clot strength with PLT >90×109/L. Although prior analyses described the contributions of platelets and fibrinogen toward clot strength, they are presented and discussed independently. The data above described clot strength as an interaction among them. Future analyses and clinical care should evaluate and recognize the interplay.

A combat casualty relevant dismounted complex blast injury model in swine.

Improvised explosive devices have resulted in a unique polytrauma injury pattern termed dismounted complex blast injury (DCBI), which is frequent in the modern military theater. Dismounted complex blast injury is characterized by extremity amputations, junctional vascular injury, and blast traumatic brain injury (bTBI). We developed a combat casualty relevant DCBI swine model, which combines hemorrhagic shock (HS) and tissue injury (TI) with a bTBI, to study interventions in this unique and devastating military injury pattern. A 50-kg male Yorkshire swine were randomized to the DCBI or SHAM group (instrumentation only). Those in the DCBI group were subjected to HS, TI, and bTBI. The blast injury was applied using a 55-psi shock tube wave. Tissue injury was created with bilateral open femur fractures. Hemorrhagic shock was induced by bleeding from femoral arteries to target pressure. A resuscitation protocol modified from the Tactical Combat Casualty Care guidelines simulated battlefield resuscitation for 240 minutes. Eight swine underwent the DCBI model and five were allocated to the SHAM group. In the DCBI model the mean base excess achieved at the end of the HS shock was -8.57 ± 5.13 mmol·L -1 . A significant coagulopathy was detected in the DCBI model as measured by prothrombin time (15.8 seconds DCBI vs. 12.86 seconds SHAM; p = 0.02) and thromboelastography maximum amplitude (68.5 mm DCBI vs. 78.3 mm in SHAM; p = 0.0003). For the DCBI models, intracranial pressure (ICP) increased by a mean of 13 mm Hg, reaching a final ICP of 24 ± 7.7 mm Hg. We created a reproducible large animal model to study the combined effects of severe HS, TI, and bTBI on coagulation and ICP in the setting of DCBI, with significant translational applications for the care of military warfighters. Within the 4-hour observational period, the swine developed a consistent coagulopathy with a concurrent brain injury evidenced by increasing ICP.

Thromboelastography maximum amplitude as an early predictor of disseminated intravascular coagulation in patients with heatstroke

Objectives The aim of this study was to investigate the ability of TEG to predict DIC associated with heatstroke. Methods We carried out a retrospective, single-center study of 67 patients with heatstroke admitted to an intensive care unit (ICU) at a comprehensive hospital between July 2016 and August 2021. Conventional coagulation tests (CCTs) and TEG were performed within 2 h of admission in ICU. Patients were diagnosed with DIC based on International Society of Thrombosis and Hemostasis criteria, and those with or without DIC were compared in terms of CCTs and TEG findings. The ability of individual parameters to predict DIC was assessed based on logistic regression and the area under receiver operating characteristic curves (AUC). Results Of the 67 patients, 19 (28.4%) were diagnosed with DIC. Compared to patients without DIC, those with DIC had significantly longer reaction time [14.5(10.6–26.0) vs. 6.2(5.1–10.1)min](p < 0.001) and kinetic time [10.9(5.9–25.0) vs. 2.7(2.2–4.7) min](p < 0.001). Conversely, those with DIC had significantly lower alpha angle [22(9.1–43.3) vs. 55.0(44.8–61.7)°](p < 0.001), maximum amplitude (MA) [(26.9(17.7–41.4) vs. 52.2(45.8–58.1) mm)] (p < 0.001) and coagulation index [-17.3(-39 to −7.9）vs. −2.4(-6.2to-0.6)](p < 0.001). MA at a cutoff value of 45.4 mm gave an AUC of 0.9 for predicting DIC, with sensitivity of 77.1%, specificity of 89.5%, positive predictive value of 10.5% and negative predictive value of 22.9%. Multifactorial logistic regression identified MA < 45.4 mm as an independent predictor of DIC (odds ratio 9, 95% confidence interval 1.2-69.2, p = 0.035). MA decreased significantly as DIC score increased and was significantly lower in the non-survivors on admission. Conclusions MA < 45.4 mm in patients with heatstroke may predict elevated risk of DIC. Highlights Patients with heatstroke-induced disseminated intravascular coagulation (DIC) has high mortality. A retrospective, single-center study was performed to investigate the ability of thromboelastography (TEG) to predict DIC associated with heatstroke. The maximum amplitude (MA) value of TEG decreased significantly with the increase of DIC score. MA < 45.4 mm was firstly demonstrated to an independent predictor of heatstroke-induced DIC.

Serial Thromboelastography and the Development of Venous Thromboembolism in Critically Ill Patients With COVID-19.

Prospective, observational cohort study. Tertiary care, academic medical center in Nashville, TN. Patients with acute respiratory failure from COVID-19 pneumonia admitted to the adult medical ICU without known VTE at enrollment. None. Ninety-eight consecutive critically ill adults with laboratory-confirmed COVID-19 were enrolled. Thromboelastography parameters and conventional coagulation parameters were measured on days 0 (within 48 hr of ICU admission), 3, 5, and 7 after enrollment. The primary outcome was diagnosis of VTE with confirmed deep venous thrombosis and/or pulmonary embolism by clinical imaging or autopsy. Twenty-six patients developed a VTE. Multivariable regression controlling for antiplatelet exposure and anticoagulation dose with death as a competing risk found that lower MA was associated with increased risk of VTE. Each 1 mm increase in enrollment and peak MA was associated with an 8% and 14% decrease in the risk of VTE, respectively (enrollment MA: subdistribution hazard ratio [SHR], 0.92; 95% CI, 0.87-0.97; p = 0.003 and peak MA: SHR, 0.86; 95% CI, 0.81-0.91; p < 0.001). Lower enrollment platelet counts and fibrinogen levels were also associated with increased risk of VTE (p = 0.002 and p = 0.01, respectively). Platelet count and fibrinogen level were positively associated with MA (multivariable model: adjusted R 2 = 0.51; p < 0.001). When controlling for the competing risk of death, lower enrollment and peak MA were associated with increased risk of VTE. Lower platelet counts and fibrinogen levels at enrollment were associated with increased risk of VTE. The association of diminished MA, platelet counts, and fibrinogen with VTE may suggest a relative consumptive coagulopathy in critically ill patients with COVID-19.

The evolution of clot strength in critically-ill COVID-19 patients: a prospective observational thromboelastography study

BackgroundFew studies detail the evolution of COVID-19 associated coagulopathy. We performed serial thromboelastography (TEG) and laboratory coagulation studies in 40 critically-ill, mechanically ventilated COVID-19 patients over a 14-day period and analysed differences between 30-day survivors and non-survivors.MethodsSingle-center prospective, observational study including 40 patients with severe COVID-19 pneumonia admitted to the intensive care unit (ICU) for mechanical ventilation. TEG analysis was performed on days 1, 7 and 14 of ICU admission and laboratory coagulation studies were performed on days 1 and 14. Coagulation variables were evaluated for change over the 14-day observation period. Differences between survivors and non-survivors at 30-days were analysed and compared.ResultsOn admission, TEG maximum amplitude (MA) with heparinase correction was above the upper limit of the reference range in 32 (80%) patients while 33 (82.5%) presented with absent clot lysis at 30 min. The functional fibrinogen MA was also elevated above the upper limit of the reference range in 37 (92.5%) patients. All patients had elevated D-dimer and fibrinogen levels, mildly prolonged prothrombin times (PT), normal platelet counts and normal activated partial thromboplastin times (aPTT). The heparinase MA decreased significantly with time and normalised after 14 days (p = < 0.001) while the increased fibrin contribution to clot strength persisted with time (p = 0.113). No significant differences in TEG analysis were noted between 30-day survivors and non-survivors at all time points. No patients developed disseminated intravascular coagulopathy (DIC) after 14-days, however thrombosis and bleeding were each reported in 3 (7.5%) patients.ConclusionCritically-ill patients with COVID-19 present in a hypercoagulable state characterised by an increased clot strength. This state normalises after 14 days despite a persistently increased fibrin contribution to clot strength. We were unable to demonstrate any significant differences in TEG parameters between 30-day survivors and non-survivors at all time points.

Coagulation profiles and viscoelastic testing in multisystem inflammatory syndrome in children.

To characterize viscoelastic testing profiles of children with multisystem inflammatory syndrome in children (MIS-C). This single-center retrospective review included 30 patients diagnosed with MIS-C from March 1 to September 1, 2020. Thromboelastography (TEG) with platelet mapping was performed in 19 (63%) patients and compared to age- and sex-matched controls prior to cardiac surgery. Relationships between TEG parameters and inflammatory markers were assessed using correlation. Patients with MIS-C had abnormal TEG results compared to controls, including decreased kinetic (K) time (1.1 vs. 1.7minutes, p<.01), increased alpha angle (75.0° vs. 65.7°, p<.01), increased maximum amplitude (70.8 vs. 58.3mm, p<.01), and decreased lysis in 30minutes (Ly30) (1.1% vs. 3.7%, p=.03); consistent with increased clot formation rate and strength, and reduced fibrinolysis. TEG maximum amplitude was moderately correlated with erythrocyte sedimentation rate (ESR) (r=0.60, p=.02), initial platelet count (r=0.67, p<.01), and peak platelet count (r=0.51, p=.03). TEG alpha angle was moderately correlated with peak platelet count (r=0.54, p=.02). Seventeen (57%) patients received aspirin (ASA) and anticoagulation, five (17%) received only ASA, and three (10%) received only anticoagulation. No patients had a symptomatic thrombotic event. Six (20%) patients had a bleeding event, none of which was major. Patients with MIS-C had evidence of hypercoagulability on TEG. Increased ESR and platelets were associated with higher clot strength. Patients were prophylactically treated with ASA or anticoagulation with no symptomatic thrombosis or major bleeding. Further multicenter study is required to characterize the rate of thrombosis and optimal thromboprophylaxis algorithm in this patient population.

Thromboelastography Changes of Whole Blood Compared to Blood Component Transfusion in Infant Craniosynostosis Surgery.

Surgical treatment of craniosynostosis with cranial vault reconstruction in infants is associated with significant blood loss. The optimal blood management approach is an area of active investigation. Thromboelastography (TEG) was used to examine changes in coagulation after surgical blood loss that was managed by transfusion with either whole blood or blood components. Transfusion type was determined by availability of whole blood from the blood bank.This retrospective study examined differences in posttransfusion TEG maximum amplitude (MA), a measure of the maximum clot strength, for patients transfused with whole blood or blood components. We included all patients less than 24 months old who underwent cranial vault remodeling, received intraoperative transfusions with whole blood or blood components, and had baseline and posttransfusion TEG measured. Whole blood was requested for all patients and was preferentially used when it was available from the American Red Cross.Of 48 eligible patients, 30 received whole blood and 18 received blood components. All patients received an intraoperative antifibrinolytic agent. The posttransfusion MA in the whole blood group was 61.8 mm (IQR 59.1, 64.1) compared to 57.9 mm (IQR 50.5, 60.9) in the blood components group (P = 0.010). There was a greater posttransfusion decrease in MA for patients transfused with blood components (median decrease of 7.7 mm [IQR -3.4, 6.3]) compared with whole blood (median decrease of 2.1 mm [IQR -9.6, 7.5] P < 0.001).Transfusion with blood components was associated with a greater decrease in MA that was likely related to decreased postoperative fibrinogen in this group. Patients who received whole blood had higher postoperative fibrinogen levels.

Prolonged Prothrombin Time in DIC: Contributions of Excess Thrombin and Fibrinogen Degradation Products

BackgroundProthrombin time (PT) is a clot-based assay that remains the clinical standard for diagnosis of coagulopathy. Prolongation of PT can be attributed to decreased fibrinogen (Fg) and dysfibrinogenemia but is commonly interpreted as a deficiency in thrombin (FIIa) generation. Paradoxically, conditions in which PT becomes prolonged (e.g., DIC, trauma) are associated with increased FIIa generation. This suggests that prolonged PT may be misleading, and efforts to improve PT in hypocoagulopathy by promoting FIIa generation may be misguided. We modeled the effects on fibrin polymerization related to varying FIIa, Fg, and Fg degradation products (FDPs, such as D-Dimer) in vitro as a platform for understanding the mechanisms underlying hypocoagulopathy.MethodsIn vitro studies were conducted using prothrombin-deficient plasmas, synthetic plasma (Fg and coagulation factors in HEPES buffered saline), and re-assembled whole blood (plasma with fresh RBCs and platelets). Concentrations of synthetic plasma components were varied to model coagulopathic states (Shaz et al. J Trauma 2011;70(6):1401-7; Johansson et al. Crit Care. 2011;15(6):R272). Assays included thromboelastography (TEG), fibrin polymerization (turbidimetry), FIIa generation (calibrated automated thrombogram, CAT), rheology, and PT/INR (Stago STA-R Evolution).ResultsIn vitro simulations of coagulopathy illustrated the significance of each factor on coagulation function. A dose response of FIIa (50-1000 nM) in prothrombin-deficient plasma demonstrated that beyond the normal FIIa range (100-200 nM), excess FIIa did not enhance clot characteristics; in fact, TEG maximum amplitude (clot strength) decreased in a FIIa dose-dependent fashion versus the equivalent dose of prothrombin (p < .001).In synthetic plasma, a similar dose-dependent FIIa effect on fibrin polymerization peak was shown at Fg concentrations of 5 and 3 mg/ml; depleting Fg to 1 mg/ml also showed this effect, but at this level clot formation was extremely poor even with optimal FIIa (Figure 1). The exponential turbidity rise as Fg converts to fibrin resulted in a time-to-peak of ~60 s for all FIIa conc. (time-to-half-peak was < 15 s). For equivalent Fg, increasing FIIa from 120 nM (peak in normal pooled blood) to 250 nM (peak in hemorrhaged coagulopathic patient; Cardenas et al. J Trauma. 2014;77(6):839-45) resulted in decreased total fibrin polymerization (p < .001 between 120 and 250 nM FIIa for all Fg values ≥ 150 mg/dl; Figure 2). With rheology, 150 nM FIIa resulted in rapidly formed clots with a significant decrease in stiffness vs. clots allowed to form by contact activation (135 Pa vs. 4.5 Pa with FIIa; p < .001).When RBCs and platelets were present, the same FIIa dose-dependent effect existed but was highly mitigated with increasing hematocrit (from 0 to 40%). The inhibitory effect of increased FIIa on fibrin polymerization was enhanced by addition of exogenous FDPs in a model of hyperfibrinolysis.ConclusionsProthrombin levels typically drop following severe hemorrhage but are sufficient to produce the active enzyme. These in vitro studies show that the prolongation of PT found in hypocoagulopathy may be a misleading diagnostic; increasing FIIa levels may improve PT but does not improve clot function. The addition of excess FIIa, while rapidly initiating clot formation, results in poorly formed clots.Excess FIIa generated during injury and hemorrhage combined with production of FDPs is mimicked in these in vitro studies, leading to a hypocoagulable state. Additionally, changes in Fg have profound effects on coagulation within the range of 100-300 mg/dl. The inhibitory effects of excess FIIa are worsened with insufficient Fg, aggravated further by D-dimer. Therefore, increases in PT under these circumstances may be attributed to poor fibrin polymerization.Hyperfibrinolysis is problematic, not just because of the breakdown of hemostasis-providing clots, but also due to the effects that FDPs have on future clot formation, particularly amplified at low Fg levels. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Association of D-dimer and Fibrinogen With Hypercoagulability in COVID-19 Requiring Extracorporeal Membrane Oxygenation.

Background:D-dimer concentration has been used by institutions to identify candidates for intensified anticoagulant treatment for venous thromboembolism prevention and for the mitigation of the microthrombotic complications associated with COVID-19. Thromboelastography (TEG) maximum amplitude (MA) has been validated as a marker of hypercoagulability and MA ≥68 mm has been utilized as a marker of hypercoagulability in other conditions.Methods:The goal of this study was to evaluate the relationship between coagulation, inflammatory, and TEG parameters in patients with COVID-19 on extracorporeal membrane oxygenation (ECMO). We performed a single-center retrospective analysis of consecutive patients that received ECMO for the treatment of COVID-19. TEG, inflammatory, and coagulation markers were compared in patients with and without a thrombotic complication. Correlation tests were performed to identify the coagulation and inflammatory markers that best predict hypercoagulability as defined by an elevated TEG MA.Results:A total of 168 TEGs were available in 24 patients. C-reactive protein and fibrinogen were significantly higher in patients that developed a thrombotic event versus those that did not (P = 0.04 and P = 0.04 respectively). D-dimer was negatively correlated with TEG MA (P < 0.01), while fibrinogen was positively correlated (P < 0.01). A fibrinogen >441 mg/dL was found to have a sensitivity of 91.2% and specificity of 85.7% for the detection of MA ≥68 mm.Conclusions:In critically ill patients with COVID-19 treated with ECMO, D-dimer concentration had an inverse relationship with degree of hypercoagulability as measured by TEG MA. D-dimer elevation may potentially reflect hemostatic perturbation in patients on ECMO or the severity of COVID-19 related sepsis rather than designate patients likely to benefit from anticoagulation. Fibrinogen concentration may represent a more useful marker of hypercoagulability in this population.

Reduced Clot Stability by Thromboelastography as a Potential Indicator of Procedure-Related Bleeding in Decompensated Cirrhosis.

In patients with decompensated cirrhosis, procedure‐related bleeding is a potentially lethal complication. Routine coagulation tests such as international normalized ratio and platelet count do not predict bleeding risk. We investigated whether thromboelastography (TEG) can identify patients with cirrhosis who are at risk of procedure‐related bleeding. As a part of a prospective study on hemostasis in decompensated cirrhosis, patients had TEG performed on admission and were followed prospectively during hospitalization for the development of procedure‐related bleeding. Eighty patients with cirrhosis were included. Among the 72 who had procedures performed, 7 had procedure‐related bleeding, which was major in three cases (two following paracentesis and one following thoracentesis). Conventional coagulation tests were comparable between bleeding and nonbleeding patients, whereas TEG parameters of k‐time (4.5 minutes vs. 2.2 minutes; P = 0.02), α‐angle (34° vs. 59°; P = 0.003), and maximum amplitude (37 mm vs. 50 mm; P = 0.004) were significantly different (all indicative of hypocoagulability). TEG maximum amplitude (MA), a marker of overall clot stability, accurately discriminated between patients who had major, life‐threatening bleeding (all with MA < 30 mm) and those who had mild or no bleeding (all with MA > 30 mm), whereas a platelet count < 50 × 109/L could not discriminate between bleeding (minor or major) and nonbleeding patients. Conclusion: In a prospective cohort of hospitalized patients with decompensated cirrhosis, TEG parameters associated with hypocoagulability appeared to predict procedure‐related bleeding, particularly a TEG MA < 30 mm. If results are validated in a larger cohort, this could be a threshold to identify patients with decompensated cirrhosis at higher risk for procedure‐related bleeding, in whom to consider preprocedural prophylaxis.

Platelet transfusion: The effects of a fluid warmer on platelet function.

Thirty-one units of hospital blood bank apheresis PLTs were obtained. PLT-rich plasma (PRP) aggregometry and thromboelastography (TEG) were performed on the unit samples before and after the units were infused through a Ranger blood/fluid warming device. There were no differences in any of the aggregometry results before and after infusion of the PLTs through the blood warmer (all P > .32). There was a significant reduction in the TEG maximum amplitude (MA) of 69.8 ± 7.9 mm before and 66.0 ± 8.8 mm after (P < .001) infusion of the PLTs through the blood warmer and α angle 61.8 ± 9.4° before and 59.3 ± 8.2° after (P = .044) infusion of the PLTs through the blood warmer, although both mean values were within normal range for the TEG and not clinically significant. There were very good correlations of aggregometry and TEG results before and after infusion of the PLTs through the blood warmer device. This study did not demonstrate significant deleterious effect on PLT function from infusing apheresis PLT units through a blood warming device by PRP aggregometry. We did detect a statistically significant-but not clinically significant-reduction in TEG MA and α angle. The prohibition of transfusing PLT units though the Ranger blood warming device is not indicated.

Thromboelastography maximum amplitude predicts short-term mortality in patients with hepatitis B virus-related acute-on-chronic liver failure.

Patients with hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACLF) exhibit complex hemostatic defects. Thromboelastography (TEG) can be used to reveal global hemostasis in patients with liver disease; however, little is known about the association between TEG and the outcome of patients with HBV-related ACLF. The present study aimed to investigate the value of TEG for predicting 90 day mortality in patients with HBV-related ACLF. A total of 51 patients with HBV-related ACLF, 26 patients with chronic hepatitis B (CHB) and 26 healthy controls (HC) were enrolled in the present study. TEG, standard coagulation tests, routine blood tests, biochemical markers and demographic variables were recorded and assessed for prognostic value. The results indicated that a prolonged reaction and kinetics (K) time, a shortened α angle and a decreased maximum amplitude (MA) and coagulation index (CI) were observed in patients with HBV-related ACLF, compared with CHB and HC subjects. Patients with HBV-related ACLF in the mortality group exhibited a decrease in α angle, MA, lysis at 30 min, CI, fibrinogen and platelet count, and an increase in K time, international normalized ratio (INR) and the model for end-stage liver disease (MELD) score in comparison with the survival group. MA and INR were two independent predictors of 90 day mortality in patients with HBV-related ACLF, with hazard ratios of 0.918 (95% CI, 0.867-0.971; P=0.003) and 3.141 (95% CI, 1.843-5.354; P<0.001) respectively. When predicting 90 day mortality, MA + INR exhibited the highest area under the receiver operating characteristic curve, followed by INR, MELD score and MA. Patients with ACLF and MA ≤51.5 mm exhibited a poorer outcome than those with MA >51.5 mm, as revealed via the Kaplan-Meier analysis. In summary, the findings of the present study suggested that TEG MA was associated with 90 day mortality in patients with HBV-related ACLF, and a combination of MA and INR was superior to MA, INR and MELD score in terms of prognostic value.

Thromboelastography Profiles of Critically Ill Patients With Coronavirus Disease 2019.

Objectives:The rate of thromboembolic events among patients with coronavirus disease 2019 is high; however, there is no robust method to identify those at greatest risk. We reviewed thromboelastography studies in critically ill patients with coronavirus disease 2019 to characterize their coagulation states.Design:Retrospective.Setting:Tertiary ICU in New York City.Patients:Sixty-four patients with coronavirus disease 2019 admitted to the ICU with thromboelastography performed.Interventions:None.Measurements and Main Results:Fifty percent of patients had a clotting index in the hypercoagulable range (clotting index > 3) (median 3.05). Reaction time and K values were below the lower limit of normal in 43.8% of the population consistent with a hypercoagulable profile. The median α angle and maximum amplitude (75.8° and 72.8 mm, respectively) were in the hypercoagulable range. The α angle was above reference range in 70.3% of patients indicative of rapid clot formation. Maximum amplitude, a factor of fibrinogen and platelet count and function, and a measure of clot strength was above reference range in 60.1% of patients. Thirty-one percent had thromboembolic events; thromboelastography parameters did not correlate with events in our cohort. Those with d-dimer values greater than 2,000 were more likely to have shorter reaction times compared with those with d-dimer levels less than or equal to 2,000 (4.8 vs 5.6 min; p = 0.001).Conclusions:A large proportion of critically ill patients with coronavirus disease 2019 have hypercoagulable thromboelastography profiles with additional derangements related to fibrinogen and platelet function. As the majority of patients have an elevated thromboelastography maximum amplitude, a follow-up study evaluating platelet aggregation would be instructive.

The Thromboelastographic Profile at Birth in Very Preterm Newborns with Patent Ductus Arteriosus

Background: The role of hemostasis in the closure of patent ductus arteriosus (PDA) in preterm infants is controversial. Objective: To assess thromboelastography (TEG) at birth in very-low-birth-weight (VLBW) infants affected by PDA. Methods: This was an ancillary study of a prospective observational study aimed at defining the TEG profile in healthy VLBW infants in the first month of life. In this analysis, we included neonates of <33 weeks’ gestational age (GA) with PDA and compared TEG traces based on (1) spontaneous closure versus the need for pharmacological treatment and (2) treatment response. We collected blood samples in the 1st day of life to perform recalcified native-blood TEG (reaction time, maximum amplitude, and lysis at 30 min [Ly30)]), standard coagulation tests, and a full blood count. Results: We enrolled 151 infants with a PDA at the first echocardiogram; 111 experienced spontaneous PDA closure while 40 required treatment. Mean GA was 29.7 ± 1.7 and 27.6 ± 2.1 weeks, and birth weight was 1,158 ± 256 and 933 ± 263 g in the 2 groups, respectively (p < 0.001). The hemostatic profile was similar between groups. Median hematocrit (44.6 and 48.7%; p = 0.01) and platelet count (187 and 216 × 10³/μL; p = 0.04) were lower in the treated group, although differences lost significance after controlling for GA and illness severity in the multivariate analysis. Responders to PDA treatment (n = 20) had a significantly lower median Ly30 than nonresponders (0 and 0.7%; p = 0.02). Conclusion: TEG at birth does not predict spontaneous PDA closure in preterm newborns. Fibrinolysis is enhanced in nonresponders to PDA treatment; this observation warrants further investigation.

Hyperthermic intraperitoneal chemotherapy enhances blood coagulation perioperatively evaluated by thromboelastography: a pilot study

Background and Objectives Postoperative thromboembolism is a significant cause of prolonged recovery in patients undergoing cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Thromboelastography (TEG) can detect hypercoagulable states and predict thromboembolic complications after surgery. This study assessed the impact of CRS and HIPEC on TEG values. Methods TEG parameters reaction time (R), kinetics time (K), angle (α), maximum amplitude (MA), and lysis percent at 60 min (LY60) were determined preoperatively, and at the end of CRS, during HIPEC, and at the end of the operation using blood samples from 15 HIPEC patients. Platelets, P-TT, and aPTT were also determined before and after CRS. Results A total of 75 samples were analyzed. During CRS, there was a significant reduction in the mean MA (3.06 mm, p = 0.001). The mean P-TT declined by 32% (p < 0.001) and mean platelets by 55 × 109/L (p < 0.001). During HIPEC, the mean R and K shortened by 1.04 min (p = 0.015) and 0.18 min (p = 0.018), respectively, whereas α increased by 2.48° (p = 0.005). Conclusions During CRS, both TEG and conventional laboratory tests indicated hypocoagulation. During HIPEC, however, the initiation of coagulation and the kinetics of thrombin formation were accelerated.

Haemostatic changes associated with fluid resuscitation in canine parvoviral enteritis.

The haemostatic status of dogs with canine parvovirus (CPV) enteritis, within 24 h of admission after initial fluid administration, has been described previously, but the haemostatic status at admission and after standard fluid resuscitation, as well as after initial fluid redistribution, has not been investigated previously. The objective of this study was to characterise the haemostatic status at admission and describe the effect of crystalloid fluid resuscitation on haemostatic variables in dogs with CPV enteritis. Twenty-seven client-owned, hospitalised dogs with confirmed natural CPV infection and 15 healthy age-matched controls were included in a prospective, observational clinical study. The volume of resuscitation fluid, haematocrit (HCT), platelet count, thromboelastography (TEG) variables, antithrombin (AT) activity, fibrinogen- and C-reactive protein (CRP) concentrations were measured in all dogs at admission, after fluid resuscitation and, in 10 dogs, after receiving an additional 3 hours of maintenance-rate crystalloid fluids. For the CPV group at admission, the median TEG reaction time (R) and maximum amplitude (MA) or clot strength, as well as the median HCT, fibrinogen and CRP concentrations, were significantly increased compared to the controls. After fluid resuscitation, median R was significantly shorter, MA significantly increased and HCT and AT activity significantly decreased compared to admission values. The haemostatic variables remained unchanged after 3 h of maintenance-rate crystalloid therapy. The increased clot strength present in dogs with CPV enteritis at admission was exacerbated after fluid resuscitation and persisted for hours after large-volume crystalloid fluid administration.