Persistent Splenic-Derived IgM Preferentially Recognize Factor VIIIA2 and C2 Domain Epitopes but Do Not Alter Antibody Production.

BACKGROUND: The most significant treatment complication for patients with hemophilia A is the development of neutralizing immunoglobin G (IgG), termed inhibitors, against factor VIII (FVIII) which prevent FVIII replacement therapy. Low titers of FVIII-specific immunoglobin M (IgM) have been identified in hemophilia A patients with and without inhibitors, as well as healthy individuals. However, the duration and influence of IgM on the immune response to FVIII remains unclear. OBJECTIVE: To characterize the binding interactions of persistently secreted FVIII-specific IgM in hemophilia A mice and assess their effect on IgG antibody development. METHODS: Splenic-derived monoclonal antibodies (MAbs) from immunized FVIII knockout mice were isolated and purified using hybridoma technology. Binding interactions were assessed utilizing a novel fluid-phase ELISA and computational modeling with HADDOCK to account for weak IgM binding. RESULTS: Sixteen porcine cross-reactive and non-inhibitory FVIII-specific IgM MAbs were identified. RNA sequencing of FVIII-specific IgM revealed 13 unique VDJ/VJ sequences indicating derivation from 13 unique B cell clones. IgM demonstrated polyclonal and polyreactive binding to FVIII in vitro and in silico. Molecular docking studies with reconstructed IgM VDJ/VJ regions identified frequent IgM interactions with amino acid residues K376, T381, K437, R2215 or K2249 within the FVIII A2 and C2 domains. Injections of individual IgM prior to FVIII exposure and co-injection of FVIII/IgM immune complexes did not affect de novo FVIII antibody production. CONCLUSION: Persistent FVIII-specific IgM are polyclonal but preferentially bind the A2 and C2 domains and FVIII/IgM immune complex formation do not significantly alter inhibitor development.

The in vitro effects of acidemia and acidemia reversal on coagulation in dogs.

Background: The effect of acidemia on blood coagulation remains inadequately understood in veterinary medicine. Therefore, we assessed the effect of in vitro acidification of canine whole blood on coagulation and investigated whether acidemia-induced coagulopathy could be reversed by reversing acidemia. Methods: Citrated whole blood samples were taken from six healthy Beagle dogs and categorized, based on pH adjustment, into neutral, weak acidemia (WA), strong acidemia (SA), and reversal from SA. Then, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen concentration, conventional thromboelastography (TEG) parameters, and velocity curve (V-curve) variables of TEG were assessed. Results: The PT, aPTT, and most TEG parameters showed significant coagulopathy in the SA group compared to the neutral group, with additional significant changes in reaction time (R), clot kinetic (K), maximum amplitude (MA), split point (SP), elasticity (E), thrombodynamic potential index (TPI), and coagulation index (CI) between the SA and WA groups. Among V-curve variables, the maximum rate of thrombus generation (MRTG) and total thrombus generation were significantly inhibited in the SA group compared to the neutral group, with significant differences in the time to maximum rate of thrombus generation (TMRTG) between the WA and SA groups. In the reverse group, aPTT, R, K, α-angle, MRTG, TMRTG, SP, TPI, and CI exhibited significant recovery compared to the SA group. Conclusion: The in vitro induction of acidemia in canine whole blood leads to impairment of coagulation profiles, and pH correction can reverse most acidemia-induced coagulopathy.

A Serendipitous Finding of Coagulation Factor VII Deficiency in Two Asymptomatic Patients.

Congenital Factor VII (FVII) deficiency is a rare autosomal recessive disorder with a prevalence of approximately 1:500,000. It plays a crucial role in initiating coagulation by activating Factors IX and X. Diagnosis typically involves prolonged prothrombin time (PT) and varies widely in clinical presentation. Management includes fresh frozen plasma (FFP), prothrombin complex concentrates (PCC), and recombinant activated FVII (rFVIIa), with rFVIIa often preferred due to its safety and efficacy. We present two pediatric cases: a five-year-old boy with a prolonged PT at 55% and FVII levels at 25.1%, and a two-year-old boy with a PT at 24% and FVII levels at 4.6%. Both cases highlight the importance of thorough hemostatic evaluation and tailored management strategies in FVII deficiency.

Production of physiological amounts of hemostatic proteins by human donor livers during ex situ long-term normothermic machine perfusion for up to 7 days.

BACKGROUND: Normothermic machine perfusion (NMP) is used for preservation and assessment of human donor livers prior to transplantation. During NMP, the liver is metabolically active, which allows detailed studies on the physiology of human livers. OBJECTIVES: To study the production of hemostatic proteins in human donor livers during NMP for up to 7 days. METHODS: In this observational study, 9 livers underwent NMP for up to 7 days with a heparinized perfusate based on red blood cells and colloids using a modified Liver Assist device (XVIVO). Perfusate samples were collected before NMP and daily thereafter for measurement of antigen and activity levels of a comprehensive panel of hemostatic proteins after heparin neutralization. RESULTS: Within 1 day, perfusate samples displayed the potential for coagulation activation as evidenced by international normalized ratio and activated partial thromboplastin assays. This was accompanied by detection of substantial quantities of functionally active coagulation proteins and inhibitors, although the specific activity of many proteins was decreased, compared with that in normal plasma. Perfusate levels of hemostatic proteins increased in the first days, reaching a stable level after 3 to 4 days of perfusion. CONCLUSION: During long-term NMP of human livers, functionally active hemostatic proteins are released into the perfusate in substantial quantities, but some proteins appear to have decreased functional properties compared with proteins in normal human plasma. We propose that NMP may be used as a platform to test efficacy of drugs that stimulate or inhibit the production of coagulation factors or to test liver-mediated clearance of prohemostatic protein therapeutics.

Rapid diagnosis of coagulopathies from vitamin K deficiency in a consecutive case cohort evaluated by comparative assessment of factor II by 1-stage assays with prothrombin time vs Ecarin reagents.

BACKGROUND: Vitamin K (VK) deficiency (VKD) impairs γ-carboxylation of VK-dependent factors (VKDFs), resulting in higher factor (F)II levels measured by Ecarin (FIIE) reagents (that convert des-γ-carboxylated FII to meizothrombin) than by prothrombin time (FII) reagents. OBJECTIVES: To evaluate FII/FIIE abnormalities among patients assessed for coagulopathies and identify findings predictive of coagulopathy improvement after VK. METHODS: We retrospectively assessed consecutive cases from 2002 to 2021 with FII/FIIE tests and the sensitivity and specificity of FII/FIIE ratios and FIIE-FII differences for VKD defined as international normalized ratio correction/improvement of ≥0.5 after VK. RESULTS: Two hundred ninety-two patients (males, 58.2%; adults, 85.6%; median age, 73 years) were evaluated (84.2% hospitalized, 48.3% in intensive care, 71.6% with active liver disease, and 28% deceased at discharge) and 25% to 38% had FII/FIIE findings suggestive of VKD. Among 170 patients assessed for response to VK, FII/FIIE ratios of ≤0.84 to 0.91 and FIIE-FII differences of >0.04 U/mL had similar modest sensitivity (47.7%-69.3%) and modest to good specificity (67.1%-91.5%) for VKD. FII/FIIE ratios of <0.86, suggestive of VKD (sensitivity, 47.7%; specificity, 90.2%), were more common in patients deficient in only VKDF (P = .0001), but were detected in 16% with non-VKDF deficiencies. Low FIIE was commonly associated with active liver disease (P = .0002). Patients with and without probable VKD (based on FII/FIIE ratios of <0.86) had similar mortality, bleeding, and rates of prothrombin complex concentrate and red cell transfusions (P ≥ .78), but fewer with probable VKD received plasma and fibrinogen replacement (P ≤ .024). CONCLUSION: FII/FIIE comparison aids the diagnosis of VKD and predicts clinical responses to VK treatment among patients with coagulopathies.

[Haemophilia B therapy: impact of the reimbursability of a long-acting recombinant factor on pharmaceutical expenditure in Italy]. / Terapia dell'emofilia B: impatto dell'ammissione alla rimborsabilità di un fattore ricombinante long-acting sulla spesa farmaceutica in Italia.

OBJECTIVES: to assess the variability in expenditure compared to 2022 assuming different rates of shifting of therapy days from current active ingredients used for the treatment of haemophilia B to nonacog beta pegolDesign: descriptive cross-sectional study. SETTING AND PARTICIPANTS: consumption in the year 2022 (data source: Medicines Utilisation Monitoring Centre, Italian Medicines Agency) of all medicinal products available in Italy containing coagulation factor IX. MAIN OUTCOMES MEASURES: for each active ingredient, the total number of therapy days and the variability in expenditure compared to 2022 were estimated on the basis of a switch of therapy days, between 5% and 20%, to nonacog beta pegol. RESULTS: on the basis of considered scenarios, the analysis shows that the total annual expenditure for clotting factors used in the treatment of haemophilia B could remain at most unchanged or reduced. Particularly, the extent of the reduction in spending could vary from 0.11% to 2.26%. This trend would be in contrast to the stable increase seen in recent years, particularly in 2022. CONCLUSIONS: this predictive spending assessment may be useful in evaluating the economic impact from new treatment options, such as etranacogene dezaparvovec gene therapy already approved by the European Medicines Agency and the Food and Drug Administration, and to improve pharmaceutical governance.

Clinical implications of a Couvelaire uterus with placental abruption: A retrospective study.

OBJECTIVE: This study aimed to clarify the maternal and neonatal outcomes based on the presence or absence of a Couvelaire uterus with placental abruption. METHODS: This single-center retrospective study was conducted at a tertiary perinatal center in Japan, including patients diagnosed with acute placental abruption who delivered live births via cesarean section between 2016 and 2023. Patients were divided into two groups based on the presence or absence of a Couvelaire uterus during surgery: the Couvelaire and normal uterus groups. Maternal and neonatal outcomes were assessed. RESULTS: This study included 76 patients: 24 in the Couvelaire group and 52 in the normal uterus group. No patients underwent hysterectomies. The Couvelaire group had significantly higher intraoperative blood loss (median 1152 vs 948 g, P = 0.010), blood transfusion rates (58% vs 31%, P = 0.022), fibrinogen administration rates (38% vs 13%, P = 0.038), intensive care unit/high care unit admission rates (29% vs 7.7%, P = 0.013), and disseminated intravascular coagulation complication rates (25% vs 7.7%, P = 0.038). There were no differences in birth weight, gestational age (median 2387 vs 2065 g, P = 0.082), Apgar score <4 at 5 min (4.2% vs 3.9%, P = 0.95), umbilical artery blood pH <7.1 (25% vs 22%, P = 0.82), and neonatal death (4.2% vs 1.9%, P = 0.57). CONCLUSION: A Couvelaire uterus indicated adverse maternal outcomes but not neonatal ones. Its presence necessitates preparation for blood transfusions and/or intensive patient follow-up.

Identifying hemophilia B carriers: Utility of aPTT, factor IX levels and ratios of factor IX to other Vitamin K dependent factors.

INTRODUCTION: Diagnosing hemophilia B (HB) carrier status is important to manage bleeding in carriers and to prevent bleeding in potential offspring. Without a family history of hemophilia, diagnosing HB carrier status is challenging. Genetic testing is the gold-standard, however it is reserved for individuals with a high suspicion of carrier status. AIMS: To describe the distribution of activated partial thromboplastin time (aPTT) and factor IX coagulant (FIX:C) levels in HB carriers and assess the ratio of FIX:C to other Vitamin K dependent factors (FII:C, FVII:C, FX:C) as an indicator of HB carrier status. METHODS: In this retrospective, single-centre cohort study, subjects were included if they were obligate or genetically proven HB carriers. Distributions of aPTT and FIX:C were described and the relationship between FIX:C levels in carriers and severity of familial HB was analysed. Ratios of FIX:C to FII:C, FVII:C, FX:C were calculated. RESULTS: Seventy-two female HB carriers (median age: 34 years; IQR 24-43) were included. Median aPTT and FIX:C levels were 33.0 s [IQR 30.0-37.0] and 57 IU/dL [IQR 43-74]. Fifteen carriers (21%) had mild HB (FIX:C levels of 10-40 IU/dL). FIX:C levels trended higher in carriers of mild HB versus carriers of moderate/severe HB. In six carriers, the median ratio of FIX:C to other Vitamin K dependent factors was 0.44, with 92% of ratios being ≤ 0.75. CONCLUSION: aPTT and FIX:C levels were unreliable in diagnosing HB carrier status. A low ratio of FIX:C to other Vitamin K dependent factors may be a useful marker of HB carrier status.

Clinical and economic burden of immune tolerance induction in entire patients with hemophilia A: Insights from a real-world Korean setting.

INTRODUCTION: The most notable challenge facing hemophilia A treatment is the development of inhibitors against factor VIII, resulting in increased clinical and socioeconomic burdens due to the need for expensive bypassing agents (BPAs). Although immune tolerance induction (ITI) is currently the primary approach for inhibiting and reducing the inhibitors, the lengthy duration of ITI necessitates the continued use of BPA to manage bleeding episodes. In this study, we aimed to obtain real-world evidence on the clinical and economic aspects and associated burdens experienced by patients with hemophilia A with inhibitors undergoing ITI in Korea. METHODS: Claims data from January 1, 2007, to December 31, 2020, were used in this study. The study cohort comprised patients with hemophilia A undergoing ITI, who were categorized into three groups: successful, failed, or continuation of ITI. We evaluated clinical and economic burdens, including monthly healthcare visits, medication costs, and total medical expenses. RESULTS: The study involved 33 cases of ITI across 32 patients. Excluding seven continuation cases where success could not be determined at the observation point, the estimated success rate of ITI was 80.8 %. The median duration of ITI for all patients was 25.7 months. While no significant disparities were noted in the ITI duration between successful and unsuccessful cases (24.51 vs. 25.66 months), substantial discrepancies were observed in the duration of BPA usage (11.10 vs. 25.66 months) and the number of prescribed BPAs (1.79 vs. 2.97). CONCLUSION: Successful ITI reduced both clinical and economic burdens, resulting in decreased monthly medication expenses and overall medical costs.

The role of coagulation factors VIII, IX and XI in the prediction and mediation of recurrent thrombotic events in children with non-central venous catheter deep vein thrombosis.

BACKGROUND: The role of elevated coagulation factors VIII (FVIII), FIX, FXI for the prediction of recurrent thrombotic events in children after an index non-central venous catheter (non-CVC) related deep vein thrombosis (DVT) remains unclear. OBJECTIVE: This study investigates the predictive role of FVIII, FIX, and FXI for recurrent thrombosis in children with index non-CVC DVTs, and the mediation effect of FVIII on chronic inflammation and recurrent thrombosis. METHODS: Children aged 0-18 years diagnosed with an index non-CVC related DVT (1993-2020) were included in this single-center retrospective cohort study. Plasma levels of FVIII, FIX, FXI were measured cross-sectionally ≥30 days after the acute DVT. The association between the continuous variables FVIII, FIX, FXI and thrombosis recurrence was investigated using uni- and multivariable logistic regression, adjusting for age, sex, and chronic inflammation. Mediation analysis assessed the role of FVIII as a mediator between chronic inflammation and recurrent thrombosis. Ethics approval was obtained. RESULTS: A total of 139 children with an index non-CVC related DVT were included. Thirty-eight (27 %) had a recurrent thrombosis at a median of 237 days (P25-P75 65-657 days) after the index DVT. In uni- and multivariable-analysis, FVIII, FIX or FXI did not predict thrombosis recurrence; However, chronic inflammation was an independent predictor. There was no evidence that FVIII mediated the effect of chronic inflammation on thrombosis recurrence. CONCLUSION: We found no evidence that elevated FVIII, FIX or FXI predicted thrombosis recurrence, or evidence of a mediating role of FVIII. Underlying chronic inflammation predicted venous recurrent thrombotic events in this cohort.

Recombinant factor IX Fc for the treatment of hemophilia B.

Current hemophilia B treatment guidelines recommend routine prophylaxis with factor IX (FIX) replacement products, tailored to maintain plasma activity at levels that will prevent bleeds. However, plasma FIX activity may not be the primary determinant or best indicator of hemostatic efficacy due to its extravascular distribution. FIX replacement therapy has evolved to include extended half-life (EHL) products that provide effective bleed protection when administered at intervals of 7 days or longer. rFIXFc is a recombinant fusion protein with an extended circulation time. rFIXFc has a biodistribution profile consistent with distribution into extravascular space, where it may support hemostasis at sites of vessel injury independent of circulating plasma activity levels. The safety and efficacy of rFIXFc prophylaxis is well established in adults, adolescents and children including previously untreated patients with hemophilia B, with substantial evidence from clinical trials and real-world clinical practice. This review describes the pharmacokinetic characteristics of rFIXFc, summarizes available safety and efficacy data, and evaluates the use of rFIXFc in special populations. Current hemophilia B treatment challenges, including target FIX plasma levels, perioperative use, and management of patients with comorbidities, are discussed together with the potential role of EHL products in the future treatment landscape of hemophilia B.

SARS-CoV-2 S protein activates NLRP3 inflammasome and deregulates coagulation factors in endothelial and immune cells.

BACKGROUND: Hyperinflammation, hypercoagulation and endothelial injury are major findings in acute and post-COVID-19. The SARS-CoV-2 S protein has been detected as an isolated element in human tissues reservoirs and is the main product of mRNA COVID-19 vaccines. We investigated whether the S protein alone triggers pro-inflammatory and pro-coagulant responses in primary cultures of two cell types deeply affected by SARS-CoV-2, such are monocytes and endothelial cells. METHODS: In human umbilical vein endothelial cells (HUVEC) and monocytes, the components of NF-κB and the NLRP3 inflammasome system, as well as coagulation regulators, were assessed by qRT-PCR, Western blot, flow cytometry, or indirect immunofluorescence. RESULTS: S protein activated NF-κB, promoted pro-inflammatory cytokines release, and triggered the priming and activation of the NLRP3 inflammasome system resulting in mature IL-1ß formation in both cell types. This was paralleled by enhanced production of coagulation factors such as von Willebrand factor (vWF), factor VIII or tissue factor, that was mediated, at least in part, by IL-1ß. Additionally, S protein failed to enhance ADAMTS-13 levels to counteract the pro-coagulant activity of vWF multimers. Monocytes and HUVEC barely expressed angiotensin-converting enzyme-2. Pharmacological approaches and gene silencing showed that TLR4 receptors mediated the effects of S protein in monocytes, but not in HUVEC. CONCLUSION: S protein behaves both as a pro-inflammatory and pro-coagulant stimulus in human monocytes and endothelial cells. Interfering with the receptors or signaling pathways evoked by the S protein may help preventing immune and vascular complications driven by such an isolated viral element. Video Abstract.

Emicizumab prophylaxis in people with hemophilia A and inhibitors: a systematic review and meta-analysis

ABSTRACT BACKGROUND: Until recently, the treatment of people with hemophilia A and inhibitors (PwHAi) was based on the use of bypassing agents (BPA). However, the advent of emicizumab as prophylaxis has demonstrated promising results. OBJECTIVES: We aimed to compare the bleeding endpoints between PwHAi on BPA and those on emicizumab prophylaxis. DESIGN AND SETTING: Systematic review of interventions and meta-analysis conducted at the Universidade Federal de Goiás, Goiânia, Goiás, Brazil. METHODS: The CENTRAL, MEDLINE, Scopus, and LILACS databases were searched on February 21, 2023. Two authors conducted the literature search, publication selection, and data extraction. The selected publications evaluated the bleeding endpoints between PwHAi on emicizumab prophylaxis and those on BPA prophylaxis. The risk of bias was evaluated according to the Joanna Briggs Institute criteria. A meta-analysis was performed to determine the annualized bleeding rate (ABR) for treated bleeds. RESULTS: Five publications (56 PwHAi) were selected from the 543 retrieved records. Overall, bleeding endpoints were lower during emicizumab prophylaxis than during BPA prophylaxis. All the publications had at least one risk of bias. The only common parameter for the meta-analysis was the ABR for treated bleeds. During emicizumab prophylaxis, the ABR for treated bleeds was lower than during BPA prophylaxis (standard mean difference: −1.58; 95% confidence interval −2.50, −0.66, P = 0.0008; I2 = 68.4%, P = 0.0031). CONCLUSION: Emicizumab was superior to BPA in bleeding prophylaxis in PwHAi. However, both the small population size and potential risk of bias should be considered when evaluating these results. SYSTEMATIC REVIEW REGISTRATION: CRD42021278726, https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=278726.

Real-World Amount of Clotting Factor Concentrates Dispensed and Annual Medical Expenditures for Japanese Patients with Hemophilia B.

Introduction: Until extended half-life (EHL) factor IX (FIX) concentrates became available in Japan in 2010, patients with hemophilia B received intravenous FIX replacement therapy with standard half-life (SHL) FIX concentrates. Purpose: To investigate the amount of factor dispensed and the associated medical expenditures for the treatment of hemophilia B in the real-world clinical setting in Japan. Methods: This retrospective study comprised patients with hemophilia B (N=197) who had filled prescriptions for FIX concentrates reported in Japan's Medical Data Vision database from 2015 to 2019. Patients were included if they had 2 or more prescriptions for the same FIX concentrates within the first 6 months of the study period and the interval between prescriptions was at least 2 weeks. Results: Since 2015, there was a decrease in the proportion of patients using SHL FIX concentrates and a corresponding increase in international units of dispensed EHL FIX concentrates. Median annualized dispensed dosages (IU/kg body weight) of EHL FIX concentrates were lower than for SHL concentrates for outpatient use only. Annual total health care expenditures per patient and annual expenditures for prescribed FIX concentrates increased each year during the study period. Following a switch from an SHL to an EHL concentrate, the median amount of prescribed FIX concentrate decreased slightly, although median total health care expenditures and FIX concentrate expenditures increased. Conclusion: In the real-world setting in Japan, medical expenditures and the proportion of patients prescribed EHL FIX concentrates for the treatment of hemophilia B have increased.

Prothrombin complex concentrate (PCC) for treatment of trauma-induced coagulopathy: systematic review and meta-analyses.

BACKGROUND: Trauma-induced coagulopathy (TIC) is common in trauma patients with major hemorrhage. Prothrombin complex concentrate (PCC) is used as a potential treatment for the correction of TIC, but the efficacy, timing, and evidence to support its use in injured patients with hemorrhage are unclear. METHODS: A systematic search of published studies was performed on MEDLINE and EMBASE databases using standardized search equations. Ongoing studies were identified using clinicaltrials.gov. Studies investigating the use of PCC to treat TIC (on its own or in combination with other treatments) in adult major trauma patients were included. Studies involving pediatric patients, studies of only traumatic brain injury (TBI), and studies involving only anticoagulated patients were excluded. Primary outcomes were in-hospital mortality and venous thromboembolism (VTE). Pooled effects of PCC use were reported using random-effects model meta-analyses. Risk of bias was assessed for each study, and we used the Grading of Recommendations Assessment, Development, and Evaluation to assess the quality of evidence. RESULTS: After removing duplicates, 1745 reports were screened and nine observational studies and one randomized controlled trial (RCT) were included, with a total of 1150 patients receiving PCC. Most studies used 4-factor-PCC with a dose of 20-30U/Kg. Among observational studies, co-interventions included whole blood (n = 1), fibrinogen concentrate (n = 2), or fresh frozen plasma (n = 4). Outcomes were inconsistently reported across studies with wide variation in both measurements and time points. The eight observational studies included reported mortality with a pooled odds ratio of 0.97 [95% CI 0.56-1.69], and five reported deep venous thrombosis (DVT) with a pooled OR of 0.83 [95% CI 0.44-1.57]. When pooling the observational studies and the RCT, the OR for mortality and DVT was 0.94 [95% CI 0.60-1.45] and 1.00 [95% CI 0.64-1.55] respectively. CONCLUSIONS: Among published studies of TIC, PCCs did not significantly reduce mortality, nor did they increase the risk of VTE. However, the potential thrombotic risk remains a concern that should be addressed in future studies. Several RCTs are currently ongoing to further explore the efficacy and safety of PCC.

New insight into the traditional model of the coagulation cascade and its regulation: illustrated review of a three-dimensional view.

The coagulation process relies on an intricate network of three-dimensional structural interactions and subtle biological regulations. In the present review, we illustrate the state of the art of the structural biology of the coagulation cascade by surveying the Protein Data Bank and the EBI AlphaFold databases. Investigations performed in the last decade have provided structural information on essentially all players involved in the process. Indeed, the initial characterization of specific and rather canonical domains has been progressively extended to complicated multidomain proteins. Recently, the application of cryogenic electron microscopy techniques has unraveled the structural features of highly complex coagulation factors, which has led to enhanced understanding. This review initially focuses on the structure of the individual factors as a function of their involvement in intrinsic, extrinsic, and common pathways. A specific emphasis is given to what is known or unknown on the structural basis of each step of the cascade. Available data providing clues on the structural recognition of the factors involved in the functional partnerships of the pathways are illustrated. Recent structures of important complexes formed by these proteins with regulators are described, focusing on the drugs used as anticoagulants and on their reversal agents. Finally, we highlight the different roles that innovative biomolecules such as aptamers may have in the regulation of the cascade.

Plasma Transfusion and Procoagulant Product Administration in Extracorporeal Membrane Oxygenation: A Secondary Analysis of an International Observational Study on Current Practices.

OBJECTIVES: To achieve optimal hemostatic balance in patients on extracorporeal membrane oxygenation (ECMO), a liberal transfusion practice is currently applied despite clear evidence. We aimed to give an overview of the current use of plasma, fibrinogen concentrate, tranexamic acid (TXA), and prothrombin complex concentrate (PCC) in patients on ECMO. DESIGN: A prespecified subanalysis of a multicenter retrospective study. Venovenous (VV)-ECMO and venoarterial (VA)-ECMO are analyzed as separate populations, comparing patients with and without bleeding and with and without thrombotic complications. SETTING: Sixteen international ICUs. PATIENTS: Adult patients on VA-ECMO or VV-ECMO. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of 420 VA-ECMO patients, 59% (n = 247) received plasma, 20% (n = 82) received fibrinogen concentrate, 17% (n = 70) received TXA, and 7% of patients (n = 28) received PCC. Fifty percent of patients (n = 208) suffered bleeding complications and 27% (n = 112) suffered thrombotic complications. More patients with bleeding complications than patients without bleeding complications received plasma (77% vs. 41%, p < 0.001), fibrinogen concentrate (28% vs 11%, p < 0.001), and TXA (23% vs 10%, p < 0.001). More patients with than without thrombotic complications received TXA (24% vs 14%, p = 0.02, odds ratio 1.75) in VA-ECMO, where no difference was seen in VV-ECMO. Of 205 VV-ECMO patients, 40% (n = 81) received plasma, 6% (n = 12) fibrinogen concentrate, 7% (n = 14) TXA, and 5% (n = 10) PCC. Thirty-nine percent (n = 80) of VV-ECMO patients suffered bleeding complications and 23% (n = 48) of patients suffered thrombotic complications. More patients with than without bleeding complications received plasma (58% vs 28%, p < 0.001), fibrinogen concentrate (13% vs 2%, p < 0.01), and TXA (11% vs 2%, p < 0.01). CONCLUSIONS: The majority of patients on ECMO receive transfusions of plasma, procoagulant products, or antifibrinolytics. In a significant part of the plasma transfused patients, this was in the absence of bleeding or prolonged international normalized ratio. This poses the question if these plasma transfusions were administered for another indication or could have been avoided.

Use of four-factor prothrombin complex concentrate (4F-PCC) for management of bleeding not associated with therapeutic anticoagulant use.

INTRODUCTION: Four-factor prothrombin complex concentrate (4F-PCC) may be an option for patients with bleeding unrelated to therapeutic anticoagulation to help with bleeding cessation and reduce blood component requirements. MATERIALS AND METHODS: Retrospective, observational study of adult patients who received 4F-PCC for bleeding not associated with therapeutic anticoagulation between June 2019 and July 2021. Primary outcome was to describe off-label 4F-PCC use in patients not on therapeutic anticoagulation for bleeding management in surgical and non-surgical patients. Additional outcomes evaluated were blood product use, chest tube and drainage output, and coagulation studies before and after 4F-PCC administration as well as other hemostatic agent use and thromboembolic events. RESULTS: Seventy-six patients were included; median age 64 years (IQR 50-69), 66% of bleeding events were associated with surgery, and the majority of 4F-PCC doses ordered by cardiac surgery (68.4%). A total of 110 4F-PCC doses were administered; median 1 dose/patient (IQR 1-2), median total dose 1000 units (IQR 500-1484). Other hemostatic agents commonly administered were protamine (59%), desmopressin (43%), and tranexamic acid (42%). Packed red blood cells, fresh frozen plasma, platelet, and cell saver blood administration and prothrombin time (PT), international normalized ratio (INR), and partial thromboplastin time (aPTT) were significantly reduced following 4F-PCC administration. Eight patients (11%) experienced thromboembolic complications. CONCLUSION: Relatively low doses of 4F-PCC (median total dose 1000 units) were associated with decreased blood component requirements and improved PT, INR, and aPTT values in patients with bleeding unrelated to therapeutic anticoagulation. Other hemostatic agent use was common and thromboembolic complications occurred.