Journal of thrombosis and haemostasis : JTH
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J. Thromb. Haemost. · Jun 2016
Platelets are dispensable for antibody-mediated transfusion-related acute lung injury in the mouse.
Essentials Role of platelets in immunological transfusion-related acute lung injury (TRALI) is debated. Immunological TRALI was tested in mice exhibiting severe thrombocytopenia or platelet dysfunction. Platelets are required to prevent lung hemorrhage but not edema formation and respiratory distress. Platelets are dispensable for the initiation and development of TRALI. ⋯ Background Transfusion-related acute lung injury (TRALI) is a serious transfusion-related complication. Previous conflicting studies have indicated that platelets are either crucial or dispensable for TRALI. Objectives To evaluate the role of platelets in major histocompatibility complex (MHC) I-induced-TRALI. Methods Antibody-mediated TRALI was experimentally induced in mice by lipopolysaccharide priming followed by the administration of an anti-MHC I mAb. Results TRALI was tested in the context of severe thrombocytopenia provoked by the administration of diphtheria toxin (DT) in transgenic iDTR mice selectively expressing DT receptor in megakaryocytes. The pathologic responses occurring within the first 10 min following the injection of the anti-MHC I mAb, i.e. the severity of lung edema and the drop in aortic blood oxygenation, were similar in severely thrombocytopenic DT-iDTR and control mice. At later times, mortality was nevertheless increased in DT-iDTR mice, owing to lung hemorrhages. When less severe thrombocytopenia was induced with an antiplatelet mAb, TRALI started and developed similarly as in control mice, but hemorrhages were absent. Furthermore, when platelet functions were defective because of administration of aspirin or clopidogrel, or because of glycoprotein (GP)IIbIIIa deficiency, TRALI still developed but no lung hemorrhages were observed. In contrast, when GPVI was immunodepleted, TRALI still occurred, but was occasionally accompanied by hemorrhages. Conclusions Platelets are dispensable for the initiation and development of MHC I-induced TRALI. Although they do not protect against the disruption of the vascular endothelial cell barrier and the subsequent plasma leakage and edema formation, platelets are essential to prevent more serious damage resulting in hemorrhages in alveoli.
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J. Thromb. Haemost. · May 2016
ReviewPeriprocedural management of patients receiving a vitamin K antagonist or a direct oral anticoagulant requiring an elective procedure or surgery.
The periprocedural management of patients receiving chronic therapy with oral anticoagulants (OACs), including vitamin K antagonists (VKAs) such as warfarin and direct OACs (DOACs), is a common clinical problem. The optimal perioperative management of patients receiving chronic OAC therapy is anchored on four key principles: (i) risk stratification of patient-related and procedure-related risks of thrombosis and bleeding; (ii) the clinical consequences of a thrombotic or bleeding event; (iii) discontinuation and reinitiation of OAC therapy on the basis of the pharmacokinetic properties of each agent; and (iv) whether aggressive management such as the use of periprocedural heparin bridging has advantages for the prevention of postoperative thromboembolism at the cost of a possible increase in bleeding risk. ⋯ There are also emerging data on periprocedural outcomes in the DOAC trials for patients with non-valvular atrial fibrillation. This review summarizes the evidence for the periprocedural management of patients receiving chronic OAC therapy, focusing on recent randomized trials and large outcome studies, to address three key clinical scenarios: (i) can OAC therapy be safely continued for minor procedures or surgeries; (ii) if therapy with VKAs (especially warfarin) needs to be temporarily interrupted for an elective procedure/surgery, is heparin bridging necessary; and (iii) what is the optimal periprocedural management of the DOACs? In answering these questions, we aim to provide updated clinical guidance for the periprocedural management of patients receiving VKA or DOAC therapy, including the use of heparin bridging.
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J. Thromb. Haemost. · May 2016
ReviewCoagulopathy and its Management in Patients with Severe Burns.
Severe burn injury is associated with systemic coagulopathy. The changes in coagulation described in patients with severe burns resemble those found patients with sepsis or major trauma. Coagulopathy in patients with severe burns is characterized by procoagulant changes, and impaired fibrinolytic and natural anticoagulation systems. ⋯ Clear guidelines for the treatment of coagulopathy in patients with severe burns are lacking, but supportive measures and targeted treatments have been proposed. Supportive measures are aimed at avoiding preventable triggers such as tissue hypoperfusion caused by shock, or hemodilution and hypothermia following the usually aggressive fluid resuscitation in these patients. Suggested targeted treatments that could benefit patients with severe burns include systemic treatment with anticoagulants, but sufficient randomized controlled trial evidence is lacking.
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J. Thromb. Haemost. · May 2016
Review Meta AnalysisPrevalence of deep vein thrombosis and pulmonary embolism in patients with superficial vein thrombosis: a systematic review and meta-analysis.
Essentials The association of superficial vein thrombosis (SVT) with venous thromboembolism (VTE) is variable. We performed a meta-analysis to assess the prevalence of concomitant VTE in patients with SVT. Deep vein thrombosis was found in 18.1%, and pulmonary embolism in 6.9%, of SVT patients. Screening for VTE may be worthy in some SVT patients to plan adequate anticoagulant treatment. ⋯ Background Some studies have suggested that patients with superficial vein thrombosis (SVT) have a non-negligible risk of concomitant deep vein thrombosis (DVT) or pulmonary embolism (PE) at the time of SVT diagnosis. Unfortunately, the available data on this association are widely variable. Objectives To perform a systematic review and meta-analysis of the literature in order to evaluate the prevalence of concomitant DVT/PE in patients with SVT of the lower limbs. Methods Studies reporting on the presence of DVT/PE in SVT patients were systematically searched for in the PubMed, Web of Science, Scopus and EMBASE databases. The weighted mean prevalence (WMP) of DVT and PE was calculated by use of the random effect model. Results Twenty-one studies (4358 patients) evaluated the prevalence of DVT and 11 studies (2484 patients) evaluated the prevalence of PE in patients with SVT. The WMP of DVT at SVT diagnosis was 18.1% (95%CI: 13.9%, 23.3%) and the WMP of PE was 6.9% (95%CI: 3.9%, 11.8%). Heterogeneity among the studies was substantial. Selection of studies including outpatients only gave similar results (WMP of DVT, 18.2%, 95% CI 12.2-26.3%; and WMP of PE, 8.2%, 95% CI 3.3-18.9%). Younger age, female gender, recent trauma and pregnancy were inversely associated with the presence of DVT/PE in SVT patients. Conclusions The results of our large meta-analysis suggest that the prevalence of DVT and PE in patients presenting with SVT is not negligible. Screening for a major thromboembolic event may be worthwhile in some SVT patients, in order to allow adequate anticoagulant treatment to be planned. Other high-quality studies are warranted to confirm our findings.
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J. Thromb. Haemost. · May 2016
Procoagulant changes in fibrin clot structure in patients with cirrhosis are associated with oxidative modifications of fibrinogen.
Essentials Patients with cirrhosis have hemostatic changes, which may contribute to a risk of thrombosis. This in vitro study compares clot formation and structure between patients and healthy subjects. Clot formation is delayed in patients; ultimately, however, clot permeability is decreased. The thrombogenic structure of fibrin clots may contribute to the thrombotic risk in cirrhosis. ⋯ Background and Objectives Patients with cirrhosis can be at risk of thrombotic complications due to an imbalance between hemostatic components. However, little is known on how the disease affects clot generation or how alterations in the structure of fibrin clots may affect the hemostatic function of these patients. Methods We investigated the formation and structure of clots generated with plasma and purified fibrinogen of 42 patients with cirrhosis. Clots generated with plasma and fibrinogen of 29 healthy volunteers were studied for comparison. Clot formation and structure were assessed by turbidity, permeation studies, confocal laser and scanning electron microscopy (SEM). The extent of fibrinogen oxidation was assessed by measuring the carbonyl content of purified fibrinogen samples. Results Tissue factor and thrombin-induced clotting of plasma was delayed in patients. The clotting rate was also decreased, but change in turbidity, fibrin density and fiber thickness were largely comparable to healthy volunteers. Conversely, clot permeability was significantly decreased in patients. When clots were generated with purified fibrinogen, differences in clot formation and structure similar to those in plasma were found. The carbonyl content was increased in patient fibrinogen and correlated with disease severity and clot permeability. Conclusions Delayed clot formation in cirrhosis ultimately results in decreased clot permeability. Similar alterations in clots generated with purified fibrinogen suggest that modifications of the molecule are (partly) responsible. Taken together, these findings are indicative of hypercoagulable features of clots of patients with cirrhosis, which may explain the increased risk of thrombosis associated with this condition.