Rate Of Clot Formation Research Articles

181 Impact of Extreme Temperatures on Hemostatic Gauzes Using Thromboelastography

In both military and wilderness/extreme civilian settings, life-threatening hemorrhage can be difficult to control. Hemostatic gauzes provide an excellent option for wounds not amenable to tourniquets. In this study, thromboelastography (TEG) was utilized to evaluate the effect of extreme temperature storage environments on the efficacy of three gauze products. Blood from 30 healthy active duty military adults was diluted by 30% with hetastarch to mimic trauma-induced coagulopathy. Temperatures were chosen because they represented thermal extremes that could be encountered in the tactical setting. Kerlix, Combat Gauze, and Chito Gauze stored for 3 weeks in cold (- 10C), hot (70C), and room-temperature (22C) environments were compared in the TEG parameters of R (time to initiation of clot formation), K (clot amplification), α angle (clot formation rate), and MA (maximum amplitude of clot) using repeated measures ANOVA with the p<.05 statistical significance threshold. Compared to whole blood, diluted blood had weaker clots with slower clot formation kinetics (MA- 58.00 vs 43.00, p<.0001; K- 2.58 vs 4.00, p<.0001; α angle- 54.98 vs 47.36, p<.0003) but faster clot initiation times (R- 8.66 vs 7.14, p<.0001). Addition of any gauze improved clot initiation times (R; Kerlix- 7.14 vs 4.98, p<.0001; Chito Gauze- 7.14 vs 5.22, p<.0001; Combat Gauze- 7.14 vs 2.71, p<.0001), with Combat Gauze significantly improving R over Chito Gauze and Kerlix. Reductions in R values were consistent across temperature extremes (p<.05) The other parameters were consistently unaffected (p>.05) Hemostatic gauze, regardless of temperature storage conditions, improved the rate of initiation of clot formation when compared to diluted blood. Additionally, our results suggest that Combat Gauze may be the best choice for extreme thermal environments.

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.

Efficacy of Anti-Thrombogenic Coating in Decreasing the Rate of Clot Formation on Indwelling Intravascular Devices during Intra-Cardiac Ablation

Background: Cardiac catheter ablation is associated with risk of thromboembolism such as stroke. Potential sources of embolism include thrombosis on guidewires, ablation catheters, and sheaths. In this study, we developed and tested a novel anti-thrombogenic coating to reduce the rate of thrombosis on indwelling intravascular devices.

Thromboelastogram-Guided Transfusion Therapy Reduces Blood-Component Transfusion and Improves Coagulation Function during Orthopedic Surgery

Massive bleeding is a serious medical complication arising from trauma, surgery, and invasive procedures. In this case, timely and effective hemostasis must be applied to patients. The aim of this study is to compare transfusion therapies guided by thromboelastogram (TEG) and conventional coagulation tests (CCTs) during orthopedic surgery, focusing on blood-component transfusion and coagulation function of patients. The patients who underwent orthopedic surgery in our hospital from May 2019 to November 2020 were retrospectively analyzed. According to different transfusion-guiding strategies, the patients were assigned into the CCT group containing 214 patients and the TEG group containing 266 patients. The TEG group used fewer volumes of blood products including red blood cell (RBC) suspension, fresh-frozen plasma, cryoprecipitate, and apheresis platelets than the CCT group ( P &lt; 0.05 ). After orthopedic surgery, the hemoglobin (Hb) and RBC counts were decreased, but the white blood cell (WBC) counts were increased in all patients receiving whether transfusion therapy guided by TEG or CCTs. Importantly, the TEG group exhibited fewer WBC counts concomitant with higher Hb and more RBC counts than the CCT group ( P &lt; 0.05 ). There was no significant difference on the platelet (PLT) counts between the two groups before and after orthopedic surgery ( P &gt; 0.05 ). Significant declines on thrombin time (TT), partial activated thromboplastin time (PATT), prothrombin time (PT), and d-dimer (D-D), along with an increase on fibrinogen (FIB) were observed in two groups after surgery. The TEG group showed reduced TT, PATT, PT, D-D, and elevated FIB compared to the CCT group ( P &lt; 0.05 ). Posttransfusion, the K value (time to reach a certain clot strength) and R value (coagulation reaction time) were decreased, the angle (α) value (clot formation rate), MA value (maximum amplitude), and CI (coagulation index) were increased in the TEG group ( P &lt; 0.05 ). When the liver function was assessed, it was found that the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total serum bilirubin (TBIL) were increased significantly, and albumin (ALB) was decreased between the two groups after surgery, but the TEG group with lower levels of ALT, AST, and TBIL and a higher level of ALB than the CCT group ( P &lt; 0.05 ). With regard to the renal function, two groups had increased levels of serum creatinine (Scr) and blood urea nitrogen (BUN) with a declined uric acid (UA) level after surgery; however, the patients in the TEG group had lower levels of Scr and BUN and a higher level of UA compared to the CCT group ( P &lt; 0.05 ). In view of above data, TEG-guided transfusion therapy could reduce use of blood products, optimize blood components, and improve coagulation function for patients undergoing orthopedic surgery. TEG-guided transfusion therapy may prevent liver and renal dysfunction after orthopedic surgery.

Effects of antithrombotic drugs on the prothrombotic state in patients with atrial fibrillation: The west Birmingham atrial fibrillation project

BackgroundDirect oral anticoagulants (DOACs) are known to prevent thrombosis but there is limited information about their activity on the clot formation and lysis cascade. ObjectivesThis study assesses the role of apixaban, one of the four licenced DOACs, on clot dynamics in patients with atrial fibrillation (AF). MethodsWe compared haemostatic and clot lysis characteristics between a group of patients with AF (n = 47) and a “disease control” group with ischaemic heart disease but in sinus rhythm (n = 39). Subsequently, we conducted clot structure studies in 3 groups of patients with AF on different antithrombotic drugs: warfarin (n = 60), apixaban (n = 60) or antiplatelets (n = 62) and in patients with AF naïve to oral anticoagulants before and after 3-months treatment with apixaban (n = 32). Haemostasis was investigated by a viscoelastic, whole blood technique (Thromboelastography/TEG), a “microplate-reader based”, citrated plasma technique (microplate assay), immunoassays to determine plasma concentrations of plasminogen activator inhibitor-1 (PAI-1), tissue-Plasminogen Activator (t-PA), D-dimer and finally platelet derived and apoptotic microparticles. ResultsPatients with AF have more potent thrombogenesis based on microplate assay indices [Rate of clot formation (p = 0.03, ƞ2 = 0.06), Maximum optical density (p < 0.001, ƞ2 = 0.05)] and delayed fibrinolysis [Rate of clot dissolution (p = 0.005, ƞ2 = 0.17)] with increased levels of apoptotic microparticles (p = 0.02, ƞ2 = 0.06) compared with the ‘disease control’ group. Apixaban was more effective in attenuating prothrombotic characteristics assessed by TEG {R (ε2 = 0.21), K (ε2 = 0.16) and angle [mean difference (MD), 95% Confidence Intervals (CI), vs warfarin 5, 0.96–8.6 and 8, 3.8–11.4 vs antiplatelets], (p < 0.001 for all indices)} compared with the other treatment groups. Patients on apixaban had lower D-dimer (p < 0.001, ε2 = 0.17) and tPA (p = 0.03, MD 90, 95%CI 6–150 vs warfarin and MD 90, 95% CI 4–150 vs antiplatelets) levels. From the microplate assay analysis, warfarin and apixaban demonstrated comparable activity based on multiple indices, both superior to antiplatelets. However, warfarin was associated with reduced fibrin network robustness (Max. optical density p < 0.001, ε2 = 0.1). Apixaban inhibited thrombosis, amplified fibrinolysis and decreased D-dimer (p = 0.001, r = 0.4) levels in the follow up study. ConclusionsPatients with AF have impaired haemostasis and elevated levels of apoptotic microparticles. Apixaban appears to affect plasma prothrombotic characteristics in a distinctive manner compared with warfarin and to reduce biomarkers associated with adverse cardiovascular events.

Tentative identification of key factors determining the hemostatic efficiency of diatom frustule.

It is increasingly essential to develop excellent materials for rapid hemorrhage control. Our previous study showed that centric diatoms such as frustules were superior to QuikClot® in hemostasis, however, related studies in pennate diatoms are still scarce. The morphological and physicochemical properties of pennate diatoms are quite different from those of centric diatoms, meaning that significant differences may also be observed from their hemostatic effects. Thus, the hemostasis effects of four pennate diatom frustules (Cocconeiopsis orthoneoides, Navicula avium, Navicula sp., and Pleurosigma indicum) were investigated in this study. Herein, all diatom frustules demonstrated outstanding hemostasis performance. For example, the in vitro coagulation time of C. orthoneoides (100.33 ± 9.5 s) was 32.4% lower than that of QuikClot®. Meanwhile, the hemostatic times of C. orthoneoides in the rat tail amputation and femoral artery models were 82 s and 180 s, respectively, only around one-half and one-third of the QuikClot® values. Moreover, the blood loss amounts of C. orthoneoides in the rat tail amputation and femoral artery model were 73.4% and 61% less than that of QuikClot®. Besides that, diatom frustules also exhibited favorable biocompatibility (hemolysis ratio <5%, MEFs cell viabilities >80%, and no inflammation). To find out the key factors underlying the hemostatic effect of frustules, Pearson correlation analysis was further performed in this study. The results demonstrated that the coagulation reaction time (R) was negatively correlated with the specific surface area and liquid absorbability but positively with the diatom pore diameter. The angle α, indicating the clot formation rate, was negative to the diatom size and pore diameter. Additionally, MA also showed a negative correlation with the BET value. This study can enrich our knowledge about the application potential of diatoms in the field of bleeding control and is helpful in deepening our understanding about the hemostatic mechanism of frustules.

Thrombodynamics as a tool for monitoring the effectiveness of anticoagulant therapy in patients with pulmonary embolism

Background . Monitoring of hemostasis in patients with pulmonary embolism (PE) to assess the efficacy and safety of anticoagulant therapy is one of the most emerging needs in clinical practice. Aim. To determine the factors associated with an insufficient decrease in the rate of fibrin clot formation in patients after pulmonary embolism receiving anticoagulation therapy. Methods. 33 patients were recruited in the study. To control plasma hemostasis, we measured coagulogram indices and performed dynamic thrombophotometry (T-2 Thrombodynamics Registrar, GemaCore, Russia). Results. The median rate of fibrin clot formation in the general sample of patients was within the normal range. However, 13 patients (39.4%) had these values higher than 29 pm/min. Patients with an insufficient decrease in the rate of fibrin clot formation were significantly younger (p = 0.045), more often had massive PE of the main branches of the pulmonary artery (p = 0.015), and high systolic pulmonary artery pressure (p = 0.043). Conclusion. Thrombodynamics allows identifying patients with PE and an increased thrombogenic potential under anticoagulation therapy by the end of the hospital stage. A high rate of fibrin clot formation by the end of the hospital period is observed in younger patients with thrombosis of the main branches of the pulmonary artery and high pulmonary hypertension.

Pathophysiology of coagulation during bleeding

Background. Analysis of 99 studies found that the predictor properties of various tests to determine the blood coagulation condition, including the newest ones (thromboelastography, rotational thromboelastometry), regarding the risk of intra- and postoperative bleeding are low. The results of prothrombin time or activated partial thromboplastin time measurements can be very variable depending on the concentration of reagents and the characteristics of the analysis. That is why standard methods of screening to assess the condition of the coagulation system in all patients in the preoperative period are not recommended.&#x0D; Objective. To describe the features of perioperative blood clotting and management of patients.&#x0D; Materials and methods. Analysis of literature data on this topic.&#x0D; Results and discussion. Before performing invasive procedures, a careful history should be taken to determine the presence and severity of previous bleeding and to ask about antithrombotic medications. If the general hemorrhagic history is favorable, further determination of coagulographic parameters is not required. If the history is unfavorable or there is evidence of potential risk factors for bleeding (e. g., liver disease), a comprehensive coagulation study should be performed. Bleeding coagulopathy is a component of the so-called lethal triad, which also includes hypothermia and acidosis. Active administration of infusion solutions can deepen or provoke coagulopathy due to hemodilution. The use of balanced infusion solutions reduces the risk of this complication. According to some authors, the fibrinogen level &lt;2 g/L is the predictor of bleeding probability. The causes of this condition include hyperfibrinolysis, dysfunctional fibrinogen in case of the administration of colloid solutions, increased decomposition of fibrinogen due to acidosis. Colloidal solutions (hydroxyethyl starch) increase the risk of reoperation and the need for transfusions, so their routine use is not currently recommended. Hyperfibrinolysis is a condition in which the rate of blood clot breakdown exceeds the rate of blood clot formation. As a result, hemorrhagic shock worsens and coagulopathy develops. Hyperfibrinolysis develops due to fibrinolytic agents and hypoperfusion. Tranexamic acid is used for heavy bleeding, in particular, postpartum. The WOMAN study involved 20,600 women with postpartum haemorrhage who received 1 g of tranexamic acid or placebo. Mortality due to bleeding in the tranexamic acid group was 1.2 %, and in the placebo group – 1.7 % (p=0.008).&#x0D; Conclusions. 1. Routine use of colloid solutions should be avoided during bleeding. 2. It is necessary to detect and eliminate anemia, hypothermia and acidosis. 3. Detection and elimination of deficiency or dysfunction of coagulation factors, hyperfibrinolysis, thrombocytopenia is an important component of bleeding prevention. 4. Reducing bleeding and improving blood clotting leads to the less need for transfusions and better outcomes for the patient.

Progress curve analysis of microtitre plate plasma clotting assays. Assessment of tissue factor levels

MTP plasma clotting assays monitor the time course of fibrin formation in re-calcified plasma by absorbance measurements and are increasingly used as alternatives to traditional one-point clot time assays employed in clinical laboratories to detect thrombotic disorders. The parameters derived from these analyses are analogous to thromboelastography viz. time, rate and maximum extent of clot formation. The derived parameters, based on the whole course of the clotting reaction are more robust, informative and quantitative than single-point clot time assays. However, the parameters themselves are usually obtained arbitrarily by crude graphical analysis of subjectively selected points of progress curves. The current work aimed to investigate the sensitivity and reproducibility of an MTP clotting assay and examine its suitability for measuring tissue factor (TF) levels in cell culture medium and patient urine. The results demonstrate that progress curves can be analysed by fitting a logistic equation, derived from a simplified autocatalytic clot formation model. The parameters, maximum amplitude (Fm), rate constant (k), time to half-maximum amplitude (tm) and maximum rate of clot formation (vm), fit a power curve showing limiting effects with increasing TF concentration. Log/log plots of tm and k against TF concentration provide standard curves for assessment of unknowns.

Comparison of intra-wound drainage tubes after cardiac surgery: Blake drains versus Multichannel drains.

Blake and Multichannel drains have been used in our department. Although both are made up of silicone, they differ in structure. We investigated the drainage effects of these two types of drains and the factors related to their occlusion. We enrolled 100 consecutive cases (50 using Blake drains and 50 using Multichannel drains) of cardiovascular surgery performed in our department from July 2017 to April 2018. The formation of thrombi in the groove and tube of the drains was evaluated in each case. The tube portion was checked for the presence of occlusion, and the groove portion was examined for the number and ratio of thrombi formed in the grooves. The clot formation rate in the groove part was slightly higher in the Multichannel cases than in the Blake cases. In addition, analysis within the Multichannel cases revealed that the thrombus formation rate between the catheter lumen and the three grooves (without the catheter lumen) was significantly different, with the highest groove clot formation rate occurring in the catheter lumen. Out of 34 cases of occlusions, there were 26 cases (52%) of Multichannel drains, and only 8 cases (16%) of Blake drains (p < 0.01). A multiple logistic regression analysis revealed that the most important contributory factor in tube obstruction was the drain type. The catheter lumen of the Multichannel drain was more susceptible to thrombus formation than the groove. The tube part of the Multichannel drain was more prone to occlusion than that of the Blake drain.

101 Thromboelastography versus Conventional Coagulation Tests in Pit Viper Envenomation and Antivenom Response

Pit viper envenomations represent a significant burden of disease worldwide, leading to severe hematologic derangements such as venom-induced consumptive coagulopathy (VICC). Recognizing this problem, the WHO recently launched a campaign to cut snake bite deaths in half by 2030. Immediacy in detection and treatment of coagulopathy with antivenom is paramount to reducing morbidity and mortality. Traditionally, administration of the pit viper antivenom, CroFab®, has been based on clinical signs and symptoms and conventional coagulation tests (CCT) such as fibrinogen, PT, PTT and INR. The purpose of this study was to assess the efficacy of TEG in detecting response to antivenom administration. Blood samples from 25 healthy adult volunteers were mixed with different concentrations of western diamondback rattlesnake (Crotalus atrox) venom (50% and 100% LD50). Each group of envenomated blood samples was treated with 4, 6, and 10 vial equivalents (vialeq) of CroFab®. All samples were assessed with CCTs including: PT, PTT, INR and Fibrinogen, as well as with TEG measures of reaction time (R), amplification (k), rate of clot formation (alpha angle), and clot strength (MA). Data was analyzed to determine the rate of return to normal range CCT and TEG values as a surrogate for return to normal coagulation. For the 50% LD50 group, CCT parameters of PT, PTT and INR returned to normal in 24%-32% of samples across all CroFab® doses. For the same group, 72% of Fibrinogen samples returned to normal at 4 vialeq with a max of 88% at 10 vialeq. TEG parameters R, k, alpha angle and MA returned to normal at a rate of 80%-96% across all CroFab doses. For the 100% LD50 group, CCT parameters of PT, PTT, and INR had a maximum of 24% return to normal for all CroFab® doses. For the same group, 16% of Fibrinogen samples returned to normal at 4 vialeq with a max of 88% at 10 vialeq. TEG parameters showed incremental increases towards normal range with 92-96% of samples in range at 10 vialeq. Pit viper envenomations are a global health threat with significant morbidity and mortality and suboptimal methods to guide the utilization of the expensive and often limited CroFab® antivenom. In this in vitro model, TEG was shown to be more sensitive than CCTs in tracking antivenom-induced recovery from VICC. Additionally, our findings represent a step towards developing a dose-response curve for antivenom administration with the potential to reduce both the amount of antivenom used and the side effects associated with its use.

A gottingen minipig model of radiation-induced coagulopathy

Purpose Total body irradiation of the Gottingen minipig results in a characteristic hematopoietic response, including anemia, neutropenia, lymphocytopenia, and thrombocytopenia. Currently, there are no well-characterized large or small animal models for radiation-induced thrombocytopenia. The study described here using the Gottingen minipig was focused on understanding which aspects of the coagulation cascade leads to radiation-induced coagulopathy. In this study, multiple clinical pathology parameters were determined prior to and for 45-days following total body irradiation using a 6 MV photon linear accelerator. Materials and methods Following irradiation, frequent analyses of conventional hematology and coagulation parameters provided time-course information on the onset and recovery of thrombocytopenia. In addition, thromboelastography (TEG) was utilized to monitor coagulation dysfunction, namely clotting time, clot formation time, clot strength, and fibrinolysis. Coagulation factor activity levels were measured for factors II, V, VII, VIII, IX, X, XI, XII, XIII, Protein C, fibrin monomers, antiplasmin and D-dimer using a Siemen’s coagulation analyzer to provide time course information of changes in activity post irradiation exposure. Results These analyses revealed that in total body irradiated minipigs, TEG tracings demonstrate long R (time to initial clot formation) and K (time to achieve a certain clot strength) times, and low alpha-angle (rate of clot formation) and MA (overall stability of the clot) during onset of thrombocytopenia (typically post irradiation day 10–15). Low alpha-angle and MA directly correlated with decreased platelet counts. A long R time is suggestive of a deficiency in clotting factors and was compared to measured activity levels of individual coagulation factors. The data indicates that coagulation factors are significantly changed early after irradiation exposure prior to thrombocytopenia and factors VIII, XI, XII and XIII are markedly altered during the critical point of thrombocytopenia. Conclusion These data support the continued use of multiple approaches to evaluate the coagulation cascade in order to provide the most meaningful interpretation of the hematopoietic changes that occur post irradiation.

Thromboelastography to Assess Coagulopathy in Traumatic Brain Injury Patients Undergoing Therapeutic Hypothermia.

Therapeutic hypothermia has been a treatment option for patients with severe traumatic brain injury (TBI) for many years. There has, however, been uncertainty whether hypothermia in this context also increased clinical bleeding risk, perhaps due to platelet dysfunction. Standard coagulation tests do not allow accurate assessment of in vivo coagulation. We studied specific coagulation abnormalities in patients undergoing therapeutic hypothermia for severe TBI using bedside thromboelastography (TEG).We studied 20 patients with severe blunt TBI from a single tertiary ICU who were enrolled in the prophylactic hypothermia to lessen traumatic brain injury (POLAR) trial. Ten patients had been randomized to hypothermia, and 10 were controls receiving normothermic standard care. TEG was undertaken during and after therapeutic hypothermia, and at the same time points in controls. Coagulation profiles were then compared between the hypothermic and control patients, and also between hypothermia and later normothermia in the study patients. Patients were primarily young (mean age 34 years) and male (85%). Measures of injury severity, including Glasgow coma score and injury severity scale, were not different between groups. Using TEG, the median alpha angle was reduced in hypothermic patients compared with controls (69.2° vs. 72.0°, p = 0.02), although both were within the normal range. LY30 was also reduced (0.0% vs. 0.5%, p < 0.01). Both differences persisted when hypothermic patients were compared with themselves during later normothermia. Therapeutic hypothermia during severe TBI causes a small decrease in the rate of clot formation. However, this decrease is within the normal range, and is unlikely to be clinically significant.

Development of a Nonwoven Hemostatic Dressing Based on Unbleached Cotton: A De Novo Design Approach.

Minimally processed greige (unbleached) cotton fibers demonstrate enhanced clotting relative to highly processed United States Pharmacopeia (USP) type 7 bleached cotton gauze. This effect is thought to be due to the material surface polarity. We hypothesized that a textile could be constructed, conserving the hemostasis-accelerating properties of greige cotton, while maintaining structural integrity and improving absorbance. Spun bond nonwovens of varying surface polarity were designed and prepared based on ratios of greige cotton/bleached cotton/polypropylene fibers. A thromboelastographic analysis was performed on fibrous samples in citrated blood to evaluate the rate of fibrin and clot formation. Lee White clotting times were obtained to assess the material’s clotting activity in platelet fresh blood. An electrokinetic analysis of samples was performed to analyze for material surface polarity. Hemostatic properties varied with composition ratios, fiber density, and fabric fenestration. The determinations of the surface polarity of cotton fabrics with electrokinetic analysis uncovered a range of surface polarities implicated in fabric-initiated clotting; a three-point design approach was employed with the combined use of thromboelastography, thrombin velocity index, Lee White clotting, and absorption capacity determinations applied to fabric structure versus function analysis. The resulting analysis demonstrates that greige cotton may be utilized, along with hydrophilic and hydrophobic fibers, to improve the initiation of fibrin formation and a decrease in clotting time in hemostatic dressings suitable to be commercially developed. Hydroentanglement is an efficient and effective process for imparting structural integrity to cotton-based textiles, while conserving hemostatic function.

Comparison of thromboelastography versus conventional coagulation tests in simulated Crotalus atrox envenomation using human blood

IntroductionPit viper bites are a source of significant morbidity and mortality. Pit viper bites can cause venom-induced consumptive coagulopathy (VICC), typically evaluated with laboratory-based conventional coagulation tests (CCTs). However, CCTs require a laboratory and average 1 h to conduct. Thromboelastography (TEG) provides real-time, point-of-care tests of coagulation that are fast and require no separate laboratory facilities, which could be advantageous in both hospital and austere settings. However, the relative efficacy of TEG versus CCTs was unclear, particularly at low venom concentrations. Therefore, the objectives of this study were to test human blood with various concentrations of pit viper venom using CCTs and TEG to determine dose-dependent changes, lowest observed effect concentration (LOEC), and sensitivity to detecting samples out of normal diagnostic range. MethodsBlood samples from 20 volunteers were mixed with varying concentrations of western diamond back rattlesnake (Crotalus atrox) venom based on the mouse LD50IV (none, 0.5%, 1%, 2%, 33%, 66%, and 100% LD50IV). Samples were split and assessed with both CCTs including prothrombin time (PT), international normalized ratio (INR), partial thromboplastin time (PTT), fibrinogen, and D-dimer, along with TEG measures of reaction time (R), kinetic time (K), rate of clot formation (α-angle), and clot strength (MA). Data were analyzed as dose-dependent concentration-based changes in raw values and in percent of samples exceeding diagnostic thresholds using ANOVA and nonparametric statistics at the p < .05 threshold. ResultsAll evaluations showed significant concentration-dependent changes, and 100% of samples exceeded diagnostic thresholds at 33%LD50IV and above, save D-dimer. At 0.5%LD50IV, R, K, α-angle, PT, and INR were significantly different from controls, and at 1%LD50IV, mean values exceeded diagnostic thresholds for R, K, α-angle, MA, PT, and INR, but not for PTT, D-dimer, or fibrinogen. At 2%LD50IV, 100% of samples were out of normal range for K, α-angle, and PT. ConclusionTEG is effective in coagulopathy evaluations of in vitro simulated pit viper envenomation. At low venom concentrations, TEG performed as well or better than the majority of CCTs. These findings provide empirical evidence supporting the use of TEG to rapidly and accurately evaluate VICC.

Successful Infliximab Treatment is Associated With Reversal of Clotting Abnormalities in Inflammatory Bowel Disease Patients.

Active inflammatory bowel diseases (IBD) represent an independent risk factor for venous thromboembolism. The authors investigated the hemostatic profile of IBD patients before and after induction treatment with infliximab, vedolizumab, and methylprednisolone. This prospective study included 62 patients with active IBD starting infliximab, vedolizumab, and/or methylprednisolone, and 22 healthy controls (HC). Plasma was collected before (w0) and after induction therapy (w14). Using a clot lysis assay, amplitude (marker for clot intensity), time to peak (Tmax; marker for clot formation rate), area under the curve (AUC; global marker for coagulation/fibrinolysis), and 50% clot lysis time (50%CLT; marker for fibrinolytic capacity) were determined. Plasminogen activator inhibitor-1 (PAI-1) and fibronectin were measured by ELISA. Clinical remission was evaluated at w14. At baseline, AUC, amplitude, and 50%CLT were significantly higher in IBD patients as compared with HC. In 34 remitters, AUC [165 (103-229)% vs. 97 (78-147)%, P=0.001], amplitude [119 (99-163)% vs. 95 (82-117)%, P=0.002], and 50%CLT [122 (94-146)% vs. 100 (87-129)%, P=0.001] decreased significantly and even normalized to the HC level. Vedolizumab trough concentration correlated inversely to fibronectin concentration (r, -0.732; P=0.002). The increase in Tmax for infliximab-treated remitters was significantly different from the decrease in Tmax for vedolizumab-treated remitters (P=0.028). The 50%CLT increased (P=0.038) when remitters were concomitantly treated with methylprednisolone. Control of inflammation using infliximab most strongly reduced those parameters that are associated with a higher risk of venous thromboembolism.

22 Thromboelastography Detects Coagulopathy Faster than Standard Coagulation Studies in Simulated Pit Viper Envenomation

Venomous snakebites pose a significant risk of morbidity and mortality in rural and austere environments, so it is not surprising that the World Health Organization recently set a goal of reducing snakebite deaths by half by 2030. Many of these envenomations are due to pit vipers, leading to severe hematologic derangements, such as venom-induced consumptive coagulopathy (VICC). Immediacy in detection of envenomations is crucial for ameliorating morbidity and mortality, but diagnosis of envenomization can be challenging, requiring access to clinical laboratory facilities. Further, the laboratory-based evaluations of coagulation function take more than an hour to conduct. In contrast, thromboelastography (TEG) is promising as a rapid, portable, bedside test of coagulation that produces meaningful results in less than 15 minutes. Therefore, the primary objective of this study was to assess the efficacy of TEG compared to standard lab tests in detecting pit viper venom at increasing concentrations. Blood samples drawn from 19 healthy adult volunteers were mixed with varying concentrations of western diamond back rattlesnake (Crotalus atrox) venom (none, 0.5%, 1%, 2%, 33%, 66%, and 100% of LD50), then assessed with standard laboratory-based tests of coagulation function (labs), including prothrombin time (PT), partial thromboplastin time (PTT), international normalized ratio (INR), D-dimer, and Fibrinogen, as well as with TEG measures of reaction time (R), amplification (K), rate of clot formation (Angle), and clot strength (MA). Data were analyzed as changes from baseline and categorized as percent of samples out of normal physiologic range, then analyzed using ANOVA and binomial statistics at the p<.05 threshold for statistical significance. TEG and standard labs were both excellent (100%) at detecting higher concentrations of venom (33%, 66%, 100%), save D-dimer. Importantly, at low venom concentration levels (0.5%, 1%, 2%), the TEG measures of R, K, alpha, and MA were similar to laboratory-based evaluations of PT and INR at detecting venom, and were significantly superior to PTT, D-dimer, and Fibrinogen. TEG provides a sensitive, real-time quantitative evaluation of coagulation derangements during simulated pit viper envenomation that is faster than standard laboratory tests. TEG was sensitive at low venom concentrations, outperforming multiple traditional laboratory evaluations of VICC. While the present study was limited to in vitro analyses, our findings suggest that TEG is a fast, effective, and portable point-of-care testing modality to assist the emergency physician community to rapidly and accurately diagnose patients stricken with venomous snake bites.

Thrombin‐generating potential, plasma clot formation, and clot lysis are impaired in patients with bleeding of unknown cause

BackgroundIn a large proportion of patients with a mild to moderate bleeding tendency no diagnosis can be established (bleeding of unknown cause, BUC). ObjectivesTo investigate possible dysfunctions in thrombin generation and plasma clot formation and lysis in patients with BUC from the Vienna Bleeding Biobank (VIBB). Patients and MethodsThrombin generation and plasma clot properties of 382 BUC patients were compared to those of 100 healthy controls and 16 patients with factor VIII (FVIII) activity ≤50%. ResultsThrombin generation was significantly impaired in BUC patients compared to healthy controls, exhibiting a prolonged lag time and time to peak and decreased maximum thrombin generation, velocity index, and area under the curve (AUC). The assessment of clot formation and lysis in BUC patients revealed a lower clot formation rate (Vmax), resulting in a longer TTP, increased absorbance (ΔAbs), and a shorter clot lysis time (CLT) than in healthy controls. Comparing patients with FVIII activity ≤ 50% to those with BUC, parameters of thrombin generation and clot formation and lysis were either stronger or comparably impaired. Bleeding severity did not correlate with parameters of thrombin generation, clot formation, or clot lysis. ConclusionPatients with BUC have an impaired hemostatic capacity reflected by a lower thrombin‐generation potential, a lower clot formation rate, increased clot turbidity, and shorter clot lysis time, which might contribute to their increased bleeding tendency. Assays monitoring these parameters can alert physicians of hemostatic impairment and should be considered in situations where traditional hemostatic lab tests fail to reveal the clinical bleeding tendency.

New insights into neonatal coagulation: normal clot formation despite lower intra-clot thrombin levels

Healthy neonates exhibit no bleeding tendencies, but exhibit longer partial thromboplastin times than adults. Lower clotting factor levels may be balanced by lower inhibitor levels, which is not reflected in routine coagulation assays, but could result in normal clot formation in vivo. The novel thrombodynamics assay simulates a damaged vessel with tissue factor immobilized to a surface. We hypothesized that intra-clot thrombin levels and spatial fibrin clot formation with this assay are comparable in neonates and adults. Coagulation was tested in plasma from venous neonatal blood (N = 12), cord blood (N = 30), and adult blood (N = 20) using thrombodynamics and calibrated automated thrombography. Neonates exhibited a higher initial rate of clot formation than adults (adult: 60.7 ± 3.9 µm/min; neonatal: 66.8 ± 3.9 µm/min; cord: 68.1 ± 3.3 µm/min; P < 0.001) and a comparable stationary rate of clot formation (adult: 35.8 ± 8.5 µm/min; neonatal: 37.0 ± 4.6 µm/min; cord: 36.0 ± 5.2 µm/min; P = 0.834). Intra-clot thrombin levels were lower in neonates (adult: 41.9 ± 11.2 AU/l; neonatal: 22.6 ± 10.2 AU/l; cord: 23.6 ± 9.7 AU/l; P < 0.001), but the longitudinal rate of thrombin propagation was comparable (adult: 27.2 ± 4.2 µm/min neonatal; 27.9 ± 2.9 µm/min; cord: 27.6 ± 3.4 µm/min; P = 0.862). Despite lower intra-clot thrombin levels, neonates exhibit normal spatial fibrin clot growth, which concurs with clinically well-functioning hemostasis in healthy neonates.

Monitoring of blood coagulation with non‐contact drop oscillation rheometry

BackgroundThromboelastography is widely used as a tool to assess the coagulation status of critical‐care patients. It allows observation of changes in the material properties of whole blood brought about by clot formation and clot lysis. However, contact activation of the coagulation cascade at surfaces of thromboelastographic systems leads to inherent variability and unreliability in predicting bleeding or thrombosis risks, while also requiring large sample volumes. ObjectivesTo develop a non‐contact drop oscillation rheometry (DOR) method to measure the viscoelastic properties of blood clots and to compare the results with current laboratory standard measurements. MethodsDrops of human blood and plasma (5‐10 μL) were acoustically levitated. Acoustic field modulation induced drop shape oscillations, and the viscoelastic properties of the sample were calculated by measuring the resonance frequency and damping ratio. ResultsDOR showed sensitivity to coagulation parameters. An increase in platelet count resulted in an increase in the maximum clot stiffness. An increase in the calcium ion level enhanced the coagulation rate prior to saturation. An increase in hematocrit resulted in a higher rate of clot formation and increased clot stiffness. Comparison of the results with those obtained with thromboelastography showed that coagulation started sooner with DOR, but with a lower rate and lower maximum stiffness. ConclusionsDOR can be used as a monitoring tool to assess blood coagulation status. The advantages of small sample size, the lack of contact and small strain (linear viscoelasticity) makes this technique unique for real‐time monitoring of blood coagulation.