Percent Of Lysis Research Articles

Utility of Thromboelastography in Detecting NOAC-Related Coagulopathy in Traumatic Brain Injury

IntroductionNovel oral anticoagulants (NOACs) have gained popularity as a vitamin K antagonist alternative without regular monitoring. There has been an increase in elderly patients on NOACs admitted for traumatic brain injury (TBI). The aim of this study is to determine the efficacy of thromboelastography (TEG) in detecting NOAC-related coagulopathy among TBI patients. MethodsA retrospective chart review of 456 TBI patients admitted to Sentara Norfolk General Hospital from 2015 to 2020 was performed. Inclusion criteria comprised patients on NOACs with a TEG performed at presentation (66 patients). Analysis included TEG values, use of prothrombin complex concentrate factor 4 (PCC4), increased intracranial hemorrhage on repeat head computed tomography within 24 h of admission, and mortality. ResultsTEG results showed 0% elevated reaction time, 1.5% elevated kinetics time, 1.5% low alpha angle, 4.5% low max amplitude, and 3.0% elevated clot lysis percent at 30 min in our cohort. Despite overwhelmingly normal TEG results, 42.42% of patients received PCC4. A subset analysis of these patients compared to those who did not receive PCC4, revealed a higher frequency of increased intracranial hemorrhage on repeat head computed tomography within 24 h of admission (42.86% versus 18.42%, P = 0.03), and increased mortality (25.0% versus 5.26%, P = 0.0219). Patients who did not receive PCC4 had no increased frequency of operative intervention or worsening of Glasgow Coma Score. ConclusionsResults suggest that TEG does not reliably assess NOAC-related coagulopathy in TBI patients. Caution must be used when interpreting TEG data to determine reversal strategies in TBI patients on NOACs.

Accelerating availability of clinically-relevant parameter estimates from thromboelastogram point-of-care device.

Modeling approaches offer a novel way to detect and predict coagulopathy in trauma patients. A dynamic model, built and tested on thromboelastogram (TEG) data, was used to generate a virtual library of over 160,000 simulated RapidTEGs. The patient-specific parameters are the initial platelet count, platelet activation rate, thrombus growth rate, and lysis rate (P(0), k1, k2, and k3, respectively). Patient data from both STAAMP (n = 182 patients) and PAMPer (n = 111 patients) clinical trials were collected. A total of 873 RapidTEGs were analyzed. One hundred sixteen TEGs indicated maximum amplitude (MA) below normal and 466 TEGs indicated lysis percent above normal. Each patient's TEG response was compared against the virtual library of TEGs to determine library trajectories having the least sum-of-squared error versus the patient TEG up to each specified evaluation time ∈ (3, 4, 5, 7.5, 10, 15, 20 minutes). Using 10 nearest-neighbor trajectories, a logistic regression was performed to predict if the patient TEG indicated MA below normal (<50 mm), lysis percent 30 minutes after MA (LY30) greater than 3%, and/or blood transfusion need using the parameters from the dynamic model. The algorithm predicts abnormal MA values using the initial 3 minutes of RapidTEG data with a median area under the curve of 0.95, and improves with more data to 0.98 by 10 minutes. Prediction of future platelet and packed red blood cell transfusion based on parameters at 4 and 5 minutes, respectively, provides equivalent predictions to the traditional TEG parameters in significantly less time. Dynamic model parameters could not predict abnormal LY30 or future fresh-frozen plasma transfusion. This analysis could be incorporated into TEG software and workflow to quickly estimate if the MA would be below or above threshold value within the initial minutes following a TEG, along with an estimate of what blood products to have on hand. Therapeutic/Care Management: Level IV.

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.

Comparison of the Coagulation Profile of Adolescent Idiopathic Scoliosis Patients Undergoing Posterior Spinal Fusion With and Without Tranexamic Acid

Study DesignProspective, observational cohort study. ObjectiveTo improve the understanding of coagulation and bleeding mechanisms during spinal deformity surgery. Summary of Background DataFibrinolysis is the mechanism of bleeding for adolescent idiopathic scoliosis undergoing posterior spinal fusion. Antifibrinolytics have become popular; however, literature to support their use remains mixed. The mechanism of action has not been demonstrated. MethodsThe coagulation profile of 88 adolescent idiopathic scoliosis patients undergoing posterior spinal fusion was analyzed. Standard coagulation laboratory investigations and thromboelastograms were drawn hourly through the case. Fifty-eight patients received no antifibrinolytic, whereas 30 patients received tranexamic acid by standardized protocol. The coagulation parameters, estimated blood loss, and transfusion requirements were compared in the two groups. ResultsThe two cohorts had no differences in demographic or surgical characteristics. Mean age was 13.6 years, 83% were female, a mean of 11.1 levels were fused, and the mean duration of surgery was 209 minutes. The tranexamic acid cohort did not demonstrate a decrease in blood loss. The transfusion rate, however, dropped from 47% in the non–tranexamic acid cohort to 23% in the tranexamic acid cohort (p = .03). Standard coagulation parameters did not differ between the groups. Fibrinolysis was diminished in the tranexamic acid cohort as measured by a Fibrinolysis score (mean maximum value 2.0 without tranexamic acid vs. 0.7 with tranexamic acid, p < .0001) and the lysis percent at 30 minutes by thromboelastogram (elevated to 3.9% without tranexamic acid vs. 1.2% with tranexamic acid at the 3-hour mark, p = .05). ConclusionsThis study provides confirmation of antifibrinolytic activity during posterior spinal fusion for adolescent idiopathic scoliosis. The presented data of fibrinolysis are proposed as standard measurements for future work on controlling blood loss during scoliosis surgery. Level of EvidenceLevel 2, prospective comparative study.

The practice of evidence based laboratory medicine among worldwide medical laboratory professionals: Competencies and need of training

Prospective, observational cohort study.To improve the understanding of coagulation and bleeding mechanisms during spinal deformity surgery.Fibrinolysis is the mechanism of bleeding for adolescent idiopathic scoliosis undergoing posterior spinal fusion. Antifibrinolytics have become popular; however, literature to support their use remains mixed. The mechanism of action has not been demonstrated.The coagulation profile of 88 adolescent idiopathic scoliosis patients undergoing posterior spinal fusion was analyzed. Standard coagulation laboratory investigations and thromboelastograms were drawn hourly through the case. Fifty-eight patients received no antifibrinolytic, whereas 30 patients received tranexamic acid by standardized protocol. The coagulation parameters, estimated blood loss, and transfusion requirements were compared in the two groups.The two cohorts had no differences in demographic or surgical characteristics. Mean age was 13.6 years, 83% were female, a mean of 11.1 levels were fused, and the mean duration of surgery was 209 minutes. The tranexamic acid cohort did not demonstrate a decrease in blood loss. The transfusion rate, however, dropped from 47% in the non–tranexamic acid cohort to 23% in the tranexamic acid cohort (p = .03). Standard coagulation parameters did not differ between the groups. Fibrinolysis was diminished in the tranexamic acid cohort as measured by a Fibrinolysis score (mean maximum value 2.0 without tranexamic acid vs. 0.7 with tranexamic acid, p < .0001) and the lysis percent at 30 minutes by thromboelastogram (elevated to 3.9% without tranexamic acid vs. 1.2% with tranexamic acid at the 3-hour mark, p = .05).This study provides confirmation of antifibrinolytic activity during posterior spinal fusion for adolescent idiopathic scoliosis. The presented data of fibrinolysis are proposed as standard measurements for future work on controlling blood loss during scoliosis surgery.Level 2, prospective comparative study.

The specifics of clotting and endogenic fibrinolysis in acute coronary syndrome patients

Aim. To assess the processes of clot formation in relation to endogenic fibrinolysis in patients with various types of acute coronary syndrome (ACS).Material and methods. To the study, 89 persons (40 males) included: 59 with ACS, 30 — control group. Among the ACS patients, 28 were ST-elevation (STEMI), 31 with non-ST-elevation ACS (NSTEACS). All participants were assessed for clotting formation parameters and thrombus lysis with rotational elastometry on ROTEM equipment (Germany) and “Hemacore” Thrombodynamics (Russia), before coronary arteriography.Results. Clot density and its size in 10 minutes were significantly higher in ACS comparing to control patients (2867 units vs 25084 units, p&lt;0,001; 41,8 mm vs 36,4 mm, p&lt;0,05, respectively). The time from onset of thrombus lysis was lower in ACS (79,4 min vs 69,3 min, p&lt;0,05). The percent of lysis by the end of process registration was lower in ACS (20,1% vs 23,1%, p&lt;0,05). Amplitude of clot formation in 20 minutes from the onset of clotting, as the maximum density of clot were significantly higher in NSTEACS comparing to STEMI (56,2 mm vs 49,7 mm, p=0,018; 59 mm vs 53,2 mm, p=0,011; respectively). Thrombus lysis was slower in NSTEACS patients comparing to STEMI (62,26 min vs 45,5 min, p=0,02).Conclusion. With the measurement in vitro, the process of clotting and thrombus lysis is more active in ACS patients comparing to controls, that point on a baseline activated hemostasis. Within the ACS group, higher the existing clot in vessel lumen, more active the shift of the balance to anticoagulation and fibrinolysis.

Thromboelastography Values Remain Hypercoagulative 6Months After Obesity Surgery: a Pilot Study.

Obesity causes a prothrombotic state and is known as a predisposing factor for thromboembolic events. In this pilot study, we assessed the impact of surgery for obesity and the subsequent weight loss on blood coagulation using traditional coagulation tests and thromboelastography (TEG). We studied blood samples from 18 patients receiving bariatric surgery. Besides traditional blood coagulation tests and high-sensitivity C-reactive protein (hsCRP) as a marker of inflammation, the TEG parameters reaction time (R), kinetics time (K), angle (α), maximum amplitude (MA), clot strength (G), and lysis percent at 60min (LY60) were determined preoperatively and on the first postoperative day and 6months after surgery. Altogether, 54 samples were analyzed. The median MA (71.3mm), G (12,403.3d/sc), and hsCRP (3.5mg/l) were elevated preoperatively. The median hsCRP further increased on the first day postoperatively, but declined to the normal range 6months after surgery, while MA and G remained elevated. In traditional coagulation tests, there was an increase in median fibrinogen and D-dimer postoperatively. D-dimer normalized (0.4mg/l) during the study period, while the fibrinogen level (4.1g/l) remained above the upper limit of normal. Measured by TEG, patients receiving bariatric surgery have hemostatic abnormalities indicating hypercoagulation at the 6-month follow-up visit, suggesting an elevated risk for thromboembolic events for at least 6months after surgery.

Whole-blood thrombelastography using calcium chloride activation in healthy cats

Thrombelastography (TEG, Haemoscope Corp., Niles, IL, USA) allows for a global evaluation of the hemostatic system; while conventional coagulation tests typically evaluate only one part of the coagulation system, TEG simultaneously examines the interaction between platelets, clotting factors, the fibrinolytic system, and clot retraction mechanisms. Since its development, TEG has been widely employed in human clinical medicine and research, but has only recently gained popularity in veterinary medicine. The purpose of this study was to establish TEG reference ranges in healthy cats using the citrated native technique. In this study, 31 clinically healthy cats were evaluated. We sampled healthy adult cats based on the absence of clinical signs of illness, normal physical examination findings, a complete blood count, hemostasis profile results, and no previous history of bleeding disorders. The cats had 2 distinct tracings: a 'normal' tracing similar to that obtained in other species, and a 'high lysis' tracing. The percent of lysis at 60 min (LY60) was significantly higher and the percent of lysis at 60 min after MA is reached (CL60) was significantly lower in the 'high lysis' group (P < 0.001 for both). Cats in the 'high lysis' group also had a significantly shorter reaction time (P = 0.02). Based on the results, citrated native TEG may provide valuable information on global hemostasis in cats. This technique has a high coefficient of variation for the reaction time, kinetic time, and LY60 parameters, likely due to platelet retraction. It should be useful for detecting hypo- and hypercoagulable states in cats with hemostatic disturbances.

Clot lysis of variant recombinant fibrinogens confirms that fiber diameter is a major determinant of lysis rate.

Previous studies have suggested that clots with thinner fiber diameter lyse at slower rates than clots with thicker fiber diameter. We examined lysis of fibrin clots formed from three variant fibrinogens, each with substitutions in the N-terminal region of the B beta chain. When we measured lysis as the rate of decrease in turbidity at 350 nm, we found that the rate of lysis was slower than normal for clots with thinner fibers. We noted, however, that the time to complete lysis was the same for all clots. Thus, when the data were considered as the percent of lysis with time, we found that the curves were the same as normal. We suggest that a complete and accurate characterization of clot dissolution requires comparison of normalized lysis rates.

Sensibilização de hemácias de carneiro e restrição à lise pelo sistema complemento do soro eqüino e de carneiro

Neste trabalho foi analisado o efeito do grau de sensibilização de hemácias de carneiro por anticorpo, na resistência à lise pelo complemento do soro eqüino e de carneiro. Os resultados mostraram que, à medida que houve um aumento do nível de sensibilização, ocorreu também um aumento da atividade do complemento homólogo, levando a 100% de lise; o mesmo foi observado para o complemento do soro eqüino, geralmente considerado ineficiente na lise destas células. A restrição à lise pode, assim, ser sobrepujada por este tratamento. Estes dados podem ser de interesse para a compreensão dos mecanismos envolvidos na modulação do fenômeno de restrição, na saúde e em doenças envolvendo o sistema complemento em animais domésticos e no homem, bem como em diagnóstico laboratorial, onde são utilizados ensaios hemolíticos para medida de atividade do complemento e pesquisa de anticorpos em amostras de soro.

Human T Cells Specifically Activated Against Autologous Malignant Melanoma

Lymphocytes from ten patients with melanoma were specifically stimulated in vitro with autologous melanoma cells and expanded in interleukin 2. Significant lysis of autologous melanoma cells was demonstrated in T cells derived from six of these patients. The mean percent of lysis of autologous tumor cells at an effector-target ratio of 20:1 was 46% among these six patients. The T cells derived from two patients developed specificity in lysing autologous melanoma cells. In both cases, specificity was enhanced by the in vitro stimulation with autologous tumor cells. Restimulation with autologous melanoma cells was associated with increasing specificity over time. Whether derived from peripheral blood lymphocytes or from lymph node cells, T cells from one patient lysed fresh autologous melanoma cells more potently than K562, allogeneic melanoma cells, and nonmelanoma cells. On day 38, at an effector-target ratio of 10:1, cell lysis of K562, an osteosarcoma, a pancreatic cancer, and three allogeneic melanomas was 3%, 4%, 7%, 8%, 7%, and 2%, respectively, while lysis of autologous melanoma cells was 47%. Specificity was maintained beyond day 60. The T cells could be expanded over 50-fold within one month.