Systemic hemostatic and hemostasiological effects of fibrin monomer in low dose under warfarin action in experiment

2019 ◽  
Author(s):  
В.М. Вдовин ◽  
А.П. Момот ◽  
Д.А. Орехов ◽  
И.Г. Толстокоров ◽  
В.О. Шевченко ◽  
...  
Keyword(s):  
Liver Injury ◽  
Blood Loss ◽  
Prothrombin Complex Concentrate ◽  
Coagulation Factors ◽  
International Normalized Ratio ◽  
Blood Coagulation Factors ◽  
Circulating Blood Volume ◽  
Hemostatic Effect ◽  
Blood Loss Volume

Введение. Ранее было показано, что фибринмономер (ФМ) в низких дозировках обладает системным гемостатическим действием в условиях дозированной травмы. Авторами выдвинута гипотеза, согласно которой ФМ способен оказывать регулирующее гемостатическое действие in vivo на фоне сниженного гемостатического потенциала. Цель исследования: изучение системных гемостатических и гемостазиологических эффектов ФМ на фоне дозированной травмы печени при гипокоагуляции, обусловленной приемом варфарина. Материалы и методы. В работе использовали 40 кроликов породы Шиншилла. Для индукции кумаринобусловленной гипокоагуляции животным per os вводили варфарин в дозе 0,4 0,5 мг/кг 14 дней до достижения международного нормализованного отношения (МНО) более 2,0. Далее животным в краевую вену уха вводили концентрат факторов протромбино вого комплекса (КФПК) в дозе 40 ЕД/кг, ФМ в дозе 0,25 мг/кг или плацебо. Через 1 ч после введения препаратов наносили травму печени и оценивали кровопотерю (в процентах от объема циркулирующей крови). Исследовали число тромбоцитов, активированное парциальное тромбопластиновое время, МНО, содержание фибриногена и Ддимера, оценивали результаты тромбоэластографии крови. Результаты. Объем кровопотери в группах животных после внутривенного введения ФМ и КФПК на фоне приема варфарина был в 9,1 раза и 6,7 раза меньше, соответственно, по сравнению с группой плацебо, получавшей тот же антикоагулянт. Вместе с тем ФМ не влиял на параметры коагулограммы (отсутствие видимого гемостазиологического эффекта) и тромбоэластограммы, тогда как применение КФПК в качестве антидота варфарина сопровождалось нормализацией параметров тромбоэластометрии и коррекцией гипокоагуляционного сдвига по МНО. Заключение. Установлено, что ФМ способен проявлять свое системное гемостатическое действие в условиях сниженного тромбинообразования, обусловленного нарушением синтеза витамин Кзависимых факторов свертывания крови. Данное действие реализуется без признаков восстановления гемостатического равновесия. Introduction. It was shown earlier that fibrinmonomer (FM) in low doses had a systemic hemostatic effect in a controlled injury condition. The authors suggest that FM is able to exert a regulating hemostatic effect in vivo under reduced hemostatic potential. Aim: to study the systemic hemostatic and hemostasiological effects of FM under controlled liver injury during hypocoagulation caused by warfarin administration. Materials and methods. In this study 40 Chinchilla rabbits were used. For the induction of coumarinmediated hypocoagulation, animals were administered per os warfarin at a dose of 0.4 0.5 mg/kg for 14 days, until an international normalized ratio (INR) was more than 2.0. Subsequently, a prothrombin complex concentrate (PCC) at a dose of 40 U/kg, FM at a dose of 0.25 mg/kg or placebo were administered into the marginal ear vein of the animals. An hour later, a liver injury was inflicted and blood loss was assessed (in percents of the circulating blood volume). The number of platelets, activated partial thromboplastin time, INR, levels of fibrinogen and Ddimer were studied and the results of blood thromboelastography were evaluated. Results. Blood loss volume in animals groups after intravenous administration of FM and PPC, under warfarin reception, was 9.1 times and 6.7 times less, respectively, compared to the placebo group receiving the same anticoagulant. However, FM did not affect on coagulogram parameters (no visible hemostasiological effect) and thromboelastogram, whereas the use of PPC as warfarin antidote was accompanied by the normalization of thromboelastometry parameters and hypocoagulation shift correction according to INR. Conclusion. It was found that FM able to manifest its systemic hemostatic effect in conditions of reduced thrombin formation caused by impaired synthesis of vitamin Kdependent blood coagulation factors. This effect is implemented without any signs of recovery of hemostatic balance.

scholarly journals Effect of an exogenous fibrin monomer on hemostatic potential and fibrin formation in the area of controlled liver injury on the background of heparin administration in experiment

2020 ◽  
pp. 32-42
Author(s):  
А.П. Момот ◽  
В.М. Вдовин ◽  
Д.А. Орехов ◽  
И.П. Бобров ◽  
И.И. Шахматов ◽  
...  
Keyword(s):  
Liver Injury ◽  
Blood Loss ◽  
Morphological Study ◽  
Fibrillar Structure ◽  
Fibrinogen Concentration ◽  
Wound Surface ◽  
Circulating Blood Volume ◽  
Hemostatic Effect ◽  
Fibrin Formation ◽  
Fibrin Monomer

Актуальность. В проведенных ранее исследованиях на «гепариновой» модели посттравматической кровопотери был продемонстрирован гемостатический эффект экзогенно вводимого фибрин-мономера (ФМ) (доза 0,25 мг/кг), сопоставимый по выраженности с применением протамина сульфата (ПС), что не получило своего объяснения из-за отсутствия данных морфологического исследования в зоне травмы печени. Цель. Сопоставить гемостатические, гемостазиологические и морфологические последствия использования ФМ, при его внутривенном введении в дозе 0,25 мг/кг, у гепаринизированных животных, после дозированной травмы печени. Материалы и методы. На 77 здоровых кроликах породы «Шиншилла» моделировали гипокоагуляцию нефракционированным гепарином (НГ) в/в в дозе 150 ед/кг. Профилактику интраоперационных кровотечений осуществляли введением ФМ в/в в дозе 0,25 мг/кг, за один час до травмы, и ПС в/в в дозе 1,5 мг/кг за 10 мин до травмы. После нанесения дозированной травмы печени кровопотерю оценивали в % от объема циркулирующей крови. Исследовали также содержание тромбоцитов в крови, активированное парциальное тромбопластиновое время (АПТВ), уровень фибриногена и количество D-димера, параметры калиброванной тромбографии. Ткани печени в области раневой поверхности для гистологических исследований получали после спонтанной остановки кровотечения. Результаты. Гепаринизированным животным была свойственна повышенная кровопотеря на фоне выраженной гипокоагуляции и снижении генерации тромбина. Применение антидота НГ - ПС, минимизировало потерю крови (снижение кровопотери в 4,0 раза по сравнению с плацебо) и приводило к восстановлению гемостатического потенциала. Согласно морфологическим исследованиям, это достигалось увеличением толщины тромботических масс (в 15,1 раза по сравнению с плацебо). В не меньшей степени гемостатический эффект был достигнут при замене ПС на ФМ (уменьшение кровопотери в 5,1 раза по сравнению с плацебо). Данные эффекты не сопровождались коррекцией гипокоагуляционного сдвига и восстановлением генерации тромбина. В последнем случае определено меньшее по выраженности фибринообразование в зоне травмы (толщина фибрина 55,2 мкм против 201,8 мкм при применении ПС; р < 0,001). Еще одной отличительной особенностью явилось отсутствие фибриллярной структуры фибрина и наличие в тромботических массах многочисленных тромбоцитов, тогда как их число в просветах сосудов рядом с раневой поверхностью было минимальным. Заключение. Приведенные данные позволяют обозначить возможные механизмы и пути остановки постравматического кровотечения при использовании гепарина. Background. In previous studies using the heparin model of post-traumatic blood loss, a hemostatic effect of exogenous fibrin monomer (FM) (0.25 mg/kg) was observed, which was comparable in intensity to the effect of protamine sulfate (PS) and remained unexplained due to the lack of morphological study data for the area of liver injury. Aim. To compare hemostatic, hemostasiological, and morphological consequences of intravenous administration of FM 0.25 mg/kg following controlled liver injury in heparinized animals. Methods. Hypocoagulation was simulated by i.v. administration of unfractionated heparin (UFH) 150 U/kg to 77 healthy Chinchilla rabbits. Intraoperative bleeding was prevented by i.v. administration of FM 0.25 mg/kg one hour prior to the injury or PS 1.5 mg/kg 10 minutes prior to the injury. After the controlled liver injury, blood loss was measured and expressed in % of the circulating blood volume. Blood platelet count, activated partial thromboplastin time (APTT), fibrinogen concentration, D-dimer concentration, and data of calibrated thrombography were also studied. Samples of liver tissue from the wound surface area were collected for histology after spontaneous arrest of bleeding. Results. Heparinized animals were characterized by increased blood loss due to pronounced hypocoagulation and decreased thrombin production. The use of the UFH antidote, PS, minimized the blood loss (by 75% compared to placebo) and resulted in restoration of the hemostatic potential. According to results of the morphological study, this effect was due to increased thickness of thrombotic masses (15.1 times compared to placebo). At least equal hemostatic effect was obtained when PS was replaced with FM (80% decrease in blood loss compared to placebo). These effects were not associated with correction of the hypocoagulation shift or recovery of the thrombin generation. In this process, fibrin formation in the injury area was less pronounced (fibrin thickness 55.2 µm vs 201.8 µm with PS; p < 0.001). Another distinctive feature was the absence of the fibrillar structure of fibrin and the presence of numerous platelets in thrombotic masses while the platelet number in the lumen of blood vessels near the wound surface was minimal.

scholarly journals Discovery of a Novel, Potent, Selective and Injectable Small Molecule Inhibitor of Blood Coagulation Factor XIa, ONO-8610539: in Vitro and in Vivo Pharmacological Profiles

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1542-1542 ◽  
Author(s):  
Masashi Gohda ◽  
Masaru Sakai ◽  
Kenji Tanaka ◽  
Tetsuya Hagio ◽  
Keizo Suzuki ◽  
...  
Keyword(s):  
Blood Loss ◽  
Blood Coagulation ◽  
Thrombus Formation ◽  
Coagulation Factor ◽  
Antithrombotic Effect ◽  
Blood Coagulation Factors ◽  
Puncture Wound ◽  
Blood Loss Volume

Abstract Introduction: Congenital human blood coagulation factor XI (FXI) deficiency is associated with bleeding that is less severe than that observed in patients with other coagulation factor deficiencies, whereas severe FXI deficiency confers the decreased risk of deep vein thrombosis. FXI knockout mice show a reduction in venous thrombus formation with no bleeding. Therefore, FXI is considered to be a promising drug target for treatment and prevention of venous thromboembolism without increasing bleeding risk. Recently, we discovered a novel, potent, selective and injectable small molecule inhibitor of activated FXI (FXIa), ONO-IG-012, and evaluated the in vitro and in vivo pharmacological profiles of the compound. Methods: In anin vitro study, inhibitory effects of ONO-IG-012 on enzyme activities of human FXIa, other blood coagulation factors, and fibrinolytic factors were evaluated. Anticoagulant effects of ONO-IG-012 were also evaluated in human and rabbit plasma. In in vivo studies, the antithrombotic and hemorrhagic effects of ONO-IG-012 were compared to those of enoxaparin in rabbit models of deep venous thrombosis and femur hemorrhage. In the thrombosis model, under ketamine and xylazine anesthesia, inferior vena cava was isolated and partially ligated to reduce blood flow. The vein at the distal site was wrapped with filter paper saturated with ferric chloride (FeCl3) solution for 15 minutes to induce endothelial injury and subsequent thrombus formation. Sixty minutes after the application of FeCl3, the thrombus wet weight was measured. In the bleeding model, a puncture wound was made into the medullary canal at the epiphysis of femur using a drill under isoflurane anesthesia and mechanical ventilation. Blood was continuously collected with absorbent cotton for one hour, and the blood loss volume was calculated from its specific gravity. Intravenous administration of ONO-IG-012 or enoxaparin was initiated as a loading dose an hour before applying FeCl3 or producing a puncture wound, followed by their maintenance dose infusion. Blood was collected to measure APTT and PT just before the administration of the compounds and applying FeCl3 or producing a puncture wound. Results: ONO-IG-012 competitively inhibited human FXIa with a Ki value of 0.0019 μmol/L. Although ONO-IG-012 moderately inhibited human plasma kallikrein with a Ki value of 0.15 μmol/L, it had little effect on other human blood coagulation factors, and fibrinolytic factors [thrombin, FVIIa, FIXa, FXa, FXIIa, tPA, urokinase, and plasmin (Ki value >100 μmol/L)]. ONO-IG-012 prolonged APTT, and the concentration required to double the APTT was 0.098 μmol/L in human plasma and 0.30 μmol/L in rabbit plasma. However, prolongation of PT was not observed even at 33 μmol/L. ONO-IG-012 inhibited thrombus formation even at a dose as low as 0.1 mg/kg/h and achieved maximum antithrombotic effect at greater than or equal to 0.3 mg/kg/h. The ex vivo APTT was increased from baseline by 1.7 ± 0.0-fold at 0.1 mg/kg/h, by 2.8 ± 0.3-fold at 0.3 mg/kg/h, and by 5.4 ± 0.4-fold at 1 mg/kg/h, while PT showed no changes at any of the concentrations tested. Enoxaparin also inhibited thrombus formation at a dose of 10 IU/kg/h, and the antithrombotic effect at 30 IU/kg/h was comparable to that of ONO-IG-012 at 0.3 mg/kg/h (−87% vs. −80%). ONO-IG-012 did not affect the blood loss volume at all even at 10 mg/kg/h, which is 33-fold higher than the dose showing maximum antithrombotic effect (0.3 mg/kg/h). At 10 mg/kg/h, the blood loss volume was 0.7 ± 0.1 mL which is not statistically significant as compared to 1.2 ± 0.3 mL in the vehicle group, and the APTT ratio was 9.0 ± 1.1-fold. In contrast, enoxaparin increased the blood loss volume dose-dependently with the values of 4.5 ± 1.8 mL (not statistically significant) at 10 IU/kg/h, 8.4 ± 2.2 mL (P <0.01) at 30 IU/kg/h, and 23.1 ± 5.0 mL (P <0.001) at 100 IU/kg/h. Conclusions: ONO-IG-012 demonstrated a competitive, highly selective and potent inhibitory effect on FXIa among proteases involved in blood coagulation or fibrinolysis and a potent anticoagulant effect on APTT. ONO-IG-012 did not affect the blood loss volume at all even at 33-fold higher dose than the dose showing the maximum antithrombotic effect comparable to enoxaparin. ONO-IG-012 is expected to be a novel potent anticoagulant without an increased risk of bleeding for the treatment and prevention of venous thromboembolism. Disclosures No relevant conflicts of interest to declare.

Prevention of massive intraoperative bleedings associated with heparin with the systemic use of fibrin monomer in the experiment

2019 ◽  
pp. 48-55
Author(s):  
А.П. Момот ◽  
В.М. Вдовин ◽  
Д.А. Орехов ◽  
Н.А. Лычёва ◽  
И.Г. Толстокоров ◽  
...  
Keyword(s):  
Liver Injury ◽  
Blood Loss ◽  
Unfractionated Heparin ◽  
Loss Rate ◽  
Antithrombin Iii ◽  
Fibrinogen Level ◽  
Circulating Blood Volume ◽  
Intraoperative Bleeding ◽  
Fibrin Monomer ◽  
Antithrombin Iii Activity

Цель исследования - изучение способности фибрин-мономера предупреждать тяжелую интраоперационную кровопотерю, ассоциированную с введением нефракционированного гепарина, при дозированной травме печени. Методика. На кроликах «Шиншилла» индуцировали гипокоагуляцию нефракционированным гепарином (150 ед/кг). Профилактику интраоперационных кровотечений осуществляли внутривенным введением фибрин-мономера (0,25 мг/кг) за 1 ч до травмы или протамина сульфата (1,5 мг/кг) за 10 мин до травмы. После нанесения стандартной травмы печени оценивали объем (в % ОЦК) и темп (мг/с) кровопотери. Анализировали число тромбоцитов, активированное парциальное тромбопластиновое время, протромбиновое и тромбиновое время свертывания, уровень фибриногена и активность антитромбина III, параметры ротационной тромбоэластометрии крови. Результаты. Объем кровопотери в группах животных после в/в введения фибрин-мономера и протамина сульфата на фоне гепаринизации был, соответственно, в 5,1 и 4,0 раза меньше по сравнению с группой плацебо, получавшей тот же антикоагулянт. Вместе с тем, фибрин-мономер не влиял на параметры коагулограммы (отсутствие видимого гемостазиологического эффекта) и тромбоэластограммы, тогда как применение протамина сульфата в качестве антидота гепарина сопровождалось нормализацией данных тромбоэластометрии и коррекцией гипокоагуляционного сдвига по активированному парциальному тромбопластиновому времени, протромбиновому и тромбиновому времени. Заключение. Установлено, что фибрин-мономер (0,25 мг/кг) снижает посттравматическое кровотечение в условиях блокады свертывания крови гепарином без видимых признаков восстановления гемостатического равновесия. The research objective was to study the ability of fibrin monomer to prevent severe intraoperative blood loss associated with administration of unfractionated heparin in controlled liver injury. Methods. Hypocoagulation was induced in chinchilla rabbits with unfractionated heparin (150 U/kg). Intraoperative bleeding was prevented by administration of fibrin monomer (FM, 0.25 mg/kg, i.v.) one hour prior to the injury and of protamine sulfate (PS, 1.5 mg/kg, i.v.) 10 min prior to the injury. Following the liver injury, blood loss was assessed as percentage of circulating blood volume and the blood loss rate (mg/s). Platelet counts, aPTT, PT, TT, fibrinogen level, antithrombin III activity, and parameters of blood rotation thromboelastometry were analyzed. Results. The volume of blood loss was 5.1 times and 4.0 times less, respectively, after the FM and PS administration during heparinization compared to the placebo group treated with the same anticoagulant. However, FM affected neither coagulogram indexes (no visible hemostasiological effect) nor thromboelastogram while the use of PS as an antidote for heparin was associated with normalization of thromboelastometric data and correction of hypercoagulative changes in aPTT, PT, TT. Conclusion. FM at a dose of 0.25 mg/kg reduced severity of posttraumatic bleeding induced by heparin inhibition of coagulation with no visible signs of hemostatic balance recovery.

Improved hemostasis with superactive analogs of factor VIIa in a mouse model of hemophilia A

Blood ◽  
2003 ◽  
Vol 102 (10) ◽  
pp. 3615-3620 ◽  
Author(s):  
Mikael Tranholm ◽  
Kim Kristensen ◽  
Annemarie T. Kristensen ◽  
Charles Pyke ◽  
Rasmus Røjkjær ◽  
...  
Keyword(s):  
Blood Loss ◽  
Bleeding Time ◽  
Hemophilia A ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Intrinsic Activity ◽  
Hemostatic Effect ◽  
Therapeutic Doses ◽  
Hemostatic Effects

AbstractIt is currently debated whether the mechanism of action of therapeutic doses of recombinant factor VIIa (rFVIIa, Novo-Seven) relies on the tissue factor (TF)-independent activity of the enzyme. The present study was conducted to investigate the in vivo hemostatic effects of rFVIIa and 3 analogs thereof with superior intrinsic activity (FVIIaIIa, K337A-FVIIaIia, and M298Q-FVIIa) in mice with antibody-induced hemophilia A. A highly significant dose response was observed for the bleeding time and blood loss for each of the rFVIIa variants. The bleeding time and blood loss were normalized after administration of 10 mg/kg rFVIIa, 3 mg/kg K337A-FVIIaIia, and 3 mg/kg M298Q-FVIIa, indicating a potency of these FVIIa analogs 3-4 times above that of rFVIIa in FVIII-depleted mice. The different in vivo potencies of the various forms of FVIIa could not be explained by the pharmacokinetics. Histopathological evaluation of kidneys revealed no signs of treatment-related pathological changes even after treatment with the superactive variants. The fact that FVIIa analogs with enhanced intrinsic activity are more efficacious in the murine hemophilia A model strongly suggests that the TF-independent procoagulant activity of FVIIa contributes to its clinical hemostatic effect. (Blood. 2003; 102:3615-3620)

o-Raffinose cross-linked hemoglobin improves the hemostatic defect associated with anemia and thrombocytopenia in rabbits

Blood ◽  
2000 ◽  
Vol 96 (10) ◽  
pp. 3630-3636 ◽  
Author(s):  
David H. Lee ◽  
Leslie Bardossy ◽  
Nichole Peterson ◽  
Morris A. Blajchman
Keyword(s):  
Blood Loss ◽  
Bleeding Time ◽  
Platelet Reactivity ◽  
Inhibitory Effect ◽  
Clinical Settings ◽  
No Donor ◽  
Hemostatic Effect ◽  
Circulating Levels

Abstract Several different preparations of cross-linked hemoglobin (CLHb) are being evaluated for their efficacy and safety as red cell substitutes in a variety of preclinical and clinical settings. Because CLHb is known to sequester nitric oxide (NO) and inhibit NO-mediated processes, we hypothesized that CLHb would have a hemostatic effect by enhancing platelet reactivity, inducing vasoconstriction, or both. Infusion of o-raffinose CLHb shortened the prolonged microvascular bleeding time and decreased blood loss from ear incisions in rabbits rendered anemic and thrombocytopenic. Moreover, this hemostatic effect persisted for at least 24 hours after infusion. Phenylephrine induced a degree of vasoconstriction similar to that induced by CLHb but did not shorten the bleeding time or decrease blood loss, suggesting that vasoconstriction alone cannot account for the hemostatic effect of CLHb. There was no evidence of CLHb-induced activation of coagulation in vivo, since infusion of CLHb did not increase circulating levels of thrombin-antithrombin complex. In vitro, CLHb abolished the inhibitory effect of the NO donor 3-morpholinosydnonimine on platelet aggregation and enhanced the aggregation of stimulated but not resting platelets. This potentiating effect was not attenuated by the addition of superoxide dismutase or catalase. To evaluate the potential arterial thrombogenicity of CLHb, a model of carotid artery thrombosis was developed in rabbits without thrombocytopenia or anemia. Compared with albumin infusion, CLHb infusion shortened the time to complete carotid occlusion. These data suggest that CLHb may shift the thromboregulatory balance toward clot formation, resulting in decreased bleeding in anemic and thrombocytopenic rabbits and possibly increasing arterial thrombogenicity in normal rabbits.

Increasing concentrations of prothrombin complex concentrate induce disseminated intravascular coagulation in a pig model of coagulopathy with blunt liver injury

Blood ◽  
2011 ◽  
Vol 118 (7) ◽  
pp. 1943-1951 ◽  
Author(s):  
Oliver Grottke ◽  
Till Braunschweig ◽  
Henri M. H. Spronk ◽  
Stephanie Esch ◽  
Annette D. Rieg ◽  
...  
Keyword(s):  
Liver Injury ◽  
Blood Loss ◽  
Disseminated Intravascular Coagulation ◽  
Prothrombin Complex Concentrate ◽  
Safety Data ◽  
Control Group ◽  
Total Blood ◽  
Intravascular Coagulation ◽  
Blunt Liver Injury ◽  
Ringer’S Lactate

Abstract Despite increasing use of prothrombin complex concentrate (PCC) to treat hemorrhage-associated coagulopathy, few studies have investigated PCC in trauma, and there is a particular lack of safety data. This study was performed to evaluate PCC therapy in a porcine model of coagulopathy with blunt liver injury. Coagulopathy was induced in 27 anesthetized pigs by replacing approximately 70% blood volume with hydroxyethyl starch 130/0.4 and Ringer's lactate solution; erythrocytes were collected and retransfused. Ten minutes after trauma, animals randomly received PCC (35 or 50 IU/kg) or saline. Coagulation parameters including thromboelastometry, thrombin generation, and blood loss were monitored for 2 hours. Internal organs were examined macroscopically and histologically to determine the presence of emboli and assess liver injury. Total blood loss was significantly lower and survival was higher in both PCC groups versus the control group (P < .05). These outcomes appeared to be dose-independent. Thromboembolism was found in all animals treated with 50 IU/kg PCC; 44% also showed signs of disseminated intravascular coagulation. Liver injury was similar in all animals. In conclusion, 35 IU/kg PCC safely improved coagulation and attenuated blood loss. However, the higher dose of PCC (50 IU/kg) appeared to increase the risk of thromboembolism and disseminated intravascular coagulation.

scholarly journals Assessment of the effect of exogenous fibrin monomer on post-traumatic bleeding in hypofibrinogenemia caused by administration of snake venom Agkistrodon rhodostoma

2020 ◽  
Vol 101 (5) ◽  
pp. 704-712
Author(s):  
V M Vdovin ◽  
A P Momot ◽  
D A Orekhov ◽  
I I Shakhmatov ◽  
N A Lycheva ◽  
...  
Keyword(s):  
Liver Injury ◽  
Blood Loss ◽  
Snake Venom ◽  
Disseminated Intravascular Coagulation ◽  
Intravascular Coagulation ◽  
Hemostatic Effect ◽  
Fibrin Monomer ◽  
Traumatic Bleeding ◽  
Post Traumatic ◽  
D Dimer

Aim. To assess the effect of fibrin monomer on the rate of blood loss after controlled liver injury in hypofibrinogenemia induced by systemic administration of Malayan pit viper venom (Agkistrodon rhodostoma). Methods. A placebo-controlled study of the hemostatic effect of fibrin monomer administered intravenously at 0.25 mg/kg, and coagulation parameters in the controlled liver injury with profound hypofibrinogenemia caused by administration of Malayan pit viper venom was conducted in 34 male Chinchilla rabbits. The distribution of the studied parameters was investigated by the ShapiroWilk test. Statistical differences between groups were tested by Students t-test, MannWhitney U test, or Wilcoxon test, as appropriate. Differences in mortality rate were examined using Fisher's exact test. Results. A model of experimental toxogenic disseminated intravascular coagulation was reproduced, manifested by high mortality of animals (50.0%), severe blood loss (increased blood loss by 1.78 times), hemolysis, a decreased platelet count (by 19.6% of median) and platelet dysfunction, fibrinogen consumption (protein content less than 0.9 g/l), hypocoagulation as well as intensive D-dimer production (increased concentration by 25.0 times of median). A high level of the fibrin derivative demonstrated activation of fibrin formation and fibrinolysis in the bloodstream of the animals. Systemic prophylactic administration of exogenous fibrin monomer after receiving snake venom did not lead to a decrease in post-traumatic bleeding, whereas earlier, during reproduction of disseminated intravascular coagulation caused by streptokinase infusion, such a hemostatic effect of fibrin monomer was shown. Conclusion. The absence of fibrin monomer effect (at a dose of 0.25 mg/kg) on the severity of blood loss in toxogenic disseminated intravascular coagulation may be associated with more profound disseminated intravascular coagulation and a sharp 25-fold increase in D-dimer levels that can act as a fibrin monomer polymerization inhibitor.

Prothrombin Complex Concentrate or Idarucizumab in a Multimodal Hemostatic Approach with Tranexamic Acid and Fibrinogen for the Acute Reversal of Dabigatran

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2275-2275
Author(s):  
Oliver Grottke ◽  
Markus Honickel ◽  
Rolf Rossaint ◽  
Till Braunschweig
Keyword(s):  
Liver Injury ◽  
Blood Loss ◽  
Tranexamic Acid ◽  
Research Funding ◽  
Prothrombin Complex Concentrate ◽  
Line Treatment ◽  
First Line ◽  
Coagulation Parameters ◽  
Hemostatic Therapy ◽  
First Line Treatment

Abstract Background: Reversal of dabigatran anticoagulation in traumatized patients with massive bleeding using idarucizumab (IDA) or prothrombin complex concentrate (PCC) together with other resuscitation measures will be first line treatment. In cases of continuous bleeding and/or elevated dabigatran levels, further hemostatic therapy with coagulation factors (tranexamic acid: TX, fibrinogen concentrate: FGN) may be required. This study tested the safety and efficacy of IDA or PCC, given as first or second line therapy in a two hit polytrauma model under dabigatran anticoagulation. A multimodal approach using TX plus FGN was also tested. In addition to the primary endpoint, reduction in blood loss (BL), a panel of coagulation parameters and the safety of these hemostatic measurements was investigated. Methods: Dabigatran etexilate (30 mg/kg bid) was given to 28 male pigs for 3 days after ethical approval. On day 4, pigs were anesthetized and given a dabigatran infusion before blunt liver injury and bilateral femur fractures. Animals were randomized to receive either 60 mg/kg IDA or 50 U/kg PCC after the first injury. One hour later these animals received the opposite treatment post second liver injury. In a second step, TX (20 mg/kg) plus FGN (100 mg/kg) were added to hemostatic therapy (IDA or PCC) after the first injury, and received the opposite hemostatic therapy (IDA 60 mg/kg or PCC 50 U/kg) after the second liver injury. BL, hemodynamic and coagulation parameters were monitored over 5 h or until death. Results: IDA as first line treatment resulted in a significant reduction in BL (IDA: 1040±202 mL) as compared to PCC (1389 ±194 mL) 60 min post injury. Despite increasing blood loss following the second trauma, the difference between groups remained significant (IDA-PCC: 1556 ± 205 mL, PCC-IDA: 1981±361 mL, P<0.0001). Likewise, in the initial TX+FGN+PCC (1696 ± 186 mL) and TX+FGN+IDA group (1416 ± 139 mL) blood loss was significantly lower compared to PCC mono-therapy (P=0.023 and P<0.0001). However, no significant difference between IDA monotherapy or TX+FGN+IDA was observed. Survival in all groups was 100%. Animals that received first IDA showed a complete reversal of coagulation parameters (e.g. aPTT, PT, thromboelastometry variables); PCC showed an improvement of clot initiation (CT) and PT, but parameters were not normalized to baseline values. The addition of FGN increased plasma concentration of fibrinogen and improved clot strength. Pathological analyses and clinical parameters including pulmonary pressure exhibited no adverse events in any of the investigated groups. Conclusion: Under conditions of ongoing blood loss after polytrauma and dabigatran anticoagulation, both IDA and PCC prevented exsanguination, although therapy with IDA was more effective. This can be explained by differences in mechanisms, IDA binds dabigatran and inhibits its anticoagulant effect, whereas PCC has no impact on dabigatran anticoagulation but nonspecifically enhances thrombin generation. Their different effects on coagulation parameters also reflect this. Moreover our data imply that clinically used multimodal hemostatic therapy with TX plus FGN and PCC or IDA appears safe under these conditions. Disclosures Grottke: NovoNordisk: Research Funding; Portola Pharmaceuticals: Consultancy; CSL Behring: Honoraria, Research Funding; Boehringer Ingelheim: Consultancy, Honoraria, Research Funding; Biotest: Research Funding. Rossaint:CSL Behring: Research Funding; Bayer Healthcare: Honoraria; Boehringer Ingelheim: Honoraria, Research Funding.

Management of Hepatic Coagulopathy in Bleeding and Nonbleeding Patients: An Evidence-Based Review

2020 ◽  
pp. 088506662090302
Author(s):  
Nicholas W. Lange ◽  
David M. Salerno ◽  
Karen Berger ◽  
Melissa M. Cushing ◽  
Robert S. Brown
Keyword(s):  
Management Strategies ◽  
Bleeding Risk ◽  
Coagulation Factors ◽  
International Normalized Ratio ◽  
Blood Products ◽  
Clotting Cascade ◽  
Clinically Significant ◽  
Pharmacologic Agents

Patients with varying degrees of hepatic dysfunction often present with presumed bleeding diathesis based on interpretation of routine measures of coagulation (prothrombin time [PT], international normalized ratio [INR], and activated partial thromboplastin time). However, standard markers of coagulation do not reflect the actual bleeding risk in this population and may lead to inappropriate administration of hemostatic agents and blood products. The concept of “rebalanced hemostasis” explains both the risk of bleeding and clotting seen in patients with liver dysfunction. The role of pharmacologic agents and blood products for prevention of bleeding during high-risk procedures and treatment of clinically significant bleeding remains unclear. Viscoelastic measurements of the clotting cascade provide information about platelets, fibrinogen/fibrin polymerization, coagulation factors, and fibrinolysis that might better represent hemostasis in vivo and may better inform management strategies. Due to the paucity of available data, firm recommendations for the use of blood products and pharmacologic agents in patients with hepatic coagulopathies are lacking, and thus, these products should not be routinely administered. Traditional laboratory tests such as PT/INR should not be the sole determinant of potential interventions. Rather, clinicians should assess factors such as the severity of bleed or bleeding risk of the procedure, the patient’s risk of thromboembolism, and the strength of available evidence for specific agents and blood products to guide decision-making.

scholarly journals In Vivo hemostatic Significance of Activated Protein C in Factor VIIIa Regulation

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 93-93
Author(s):  
Amelia R. Wilhelm ◽  
Nicole A. Parsons ◽  
Charles T. Esmon ◽  
Rodney M. Camire ◽  
Lindsey A. George
Keyword(s):  
Blood Loss ◽  
Protein C ◽  
Activated Protein C ◽  
Enzyme Complex ◽  
Hemostatic Effect ◽  
Safety Considerations ◽  
A2 Domain ◽  
Tail Clip

Activated factor VIII (FVIIIa) is an essential cofactor in the intrinsic tenase (Xase) enzyme complex that generates factor Xa and propagates clot formation. The FVIIIa heterotrimer is comprised of a metal ion linked dimer (A1/A3-C1-C2 domains) that is associated with the A2 domain by weak non-covalent interactions. Regulation of FXa formation by the intrinsic Xase enzyme complex occurs by FIXa inhibition and mechanisms contributing to FVIIIa inactivation, including: 1) rapid A2 domain dissociation and 2) activated protein C (APC) cleavage of FVIIIa. While FVIIIa inactivation by APC is considered important, there are surprisingly no in vivo studies documenting the hemostatic role of APC in FVIIIa regulation. Further, published data demonstrate APC cleavage of FVIIIa at physiologic protein concentrations occurs over hours while A2 dissociation occurs rapidly over minutes. Thus, it is thought that the predominant mechanism of FVIIIa inactivation is A2 dissociation and APC likely plays a marginal role in FVIIIa regulation. Additionally, unlike described A2 mutations that enhance dissociation and cause hemophilia A (HA), there is no known disease state attributed to altered FVIIIa cleavage by APC. This is in contrast to FVIII's homologous protein, FVa, whereby resistance to APC cleavage is the most common inherited thrombophilia (FV-Leiden [FVL]). Understanding the physiologically relevant mechanisms of FVIIIa inactivation has immediate clinical applicability for understanding safety considerations in HA therapeutics that bypass FVIIIa regulation (FVIII mimetic antibodies, e.g. emicizumab). Further, as evidenced by successful hemophilia B gene therapy trials using a gain of function FIX variant (FIX-Padua), altering FVIIIa inactivation could be exploited for therapeutic benefit in the setting of gene transfer. We aimed to determine the in vivo hemostatic role of APC in FVIIIa regulation and pair these studies with purified system analysis. We introduced Arg to Gln mutations at FVIII APC cleavage sites (R336Q and R562Q, herein called FVIII-QQ) on a B-domain deleted FVIII (FVIII-WT) backbone and produced recombinant FVIII-QQ and FVIII-WT. Unlike FVIII-WT, western blot analysis of FVIII-QQ incubated with APC and phospholipids had no evidence of cleavage. Enzyme kinetic studies using purified components demonstrated no appreciable difference in the Km or Vmax for FX within the intrinsic Xase enzyme complex or A2 dissociation of FVIII-QQ relative to FVIII-WT. These data confirmed no unexpected differences in FVIII-QQ relative to FVIII-WT. To begin to evaluate the role of APC in FVIIIa regulation, we measured thrombin generation in murine and human HA plasma reconstituted with FVIII-QQ or FVIII-WT in the presence of increasing APC concentrations. The IC50 of APC was 2-3-fold higher for FVIII-QQ than FVIII-WT. To evaluate the in vivo hemostatic effect of APC in FVIIIa regulation, HA mice were infused with FVIII-QQ or FVIII-WT and evaluated by tail clip injury and 7.5% FeCl3 carotid artery occlusion models. Required doses of FVIII-QQ to normalize blood loss from a tail clip assay and time to vessel occlusion in a FeCl3 assay were 4-5 fold lower than necessary FVIII-WT doses; the superior hemostatic effect of FVIII-QQ supported the physiologic significance of APC in FVIIIa inactivation. To isolate the role of APC in FVIIIa regulation from APC inactivation of FVa, we backcrossed HA mice with FVL mice to create homozygous HA/FVL mice. HA/FVL mice were infused with FVIII-QQ or FVIII-WT and underwent tail clip assay analysis. Doses of FVIII-QQ required to normalize blood loss were again less than FVIII-WT. To further isolate the enhanced hemostatic effect of FVIII-QQ to APC resistance, we performed the tail clip assay in HA/FVL mice infused with FVIII-QQ or FVIII-WT in the presence or absence of MPC1609, an antibody that blocks murine APC function (Xu et al. J Thromb Haemost 2008). In the presence of MPC1609, the same dose of FVIII-WT and FVIII-QQ was required to normalize blood loss (Figure 1). Collectively, our in vitro and in vivo data support the physiologic significance of APC in FVIIIa regulation. To our knowledge these data are the first to demonstrate the in vivo hemostatic effect of APC in FVIIIa inactivation. Our data may be translated to rationally exploit APC regulation of FVIIIa to develop novel HA therapeutics or further delineate safety considerations in therapies that bypass FVIIIa regulation. Figure 1 Disclosures Camire: Pfizer: Research Funding. George:University of Pennyslvania: Employment; Pfizer: Consultancy; Avrobio: Membership on an entity's Board of Directors or advisory committees.

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