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The use of prothrombin complex concentrates and the role of plasma concentration of anticoagulants in the management of bleeding in patients treated with direct oral anticoagulants are still debated. Our aim was to describe management strategies and outcomes of severe bleeding events in patients treated with direct oral anticoagulants.We performed a prospective cohort study of 732 patients treated with dabigatran, rivaroxaban, or apixaban hospitalized for severe bleeding, included prospectively in the registry from June 2013 to November 2015.Bleeding was gastrointestinal or intracranial in 37% (212 of 732) and 24% (141 of 732) of the cases, respectively. Creatinine clearance was lower than 60 ml/min in 61% (449 of 732) of the cases. The plasma concentration of direct oral anticoagulants was determined in 62% (452 of 732) of the cases and was lower than 50 ng/ml or higher than 400 ng/ml in 9.2% (41 of 452) and in 6.6% (30 of 452) of the cases, respectively. Activated or nonactivated prothrombin complex concentrates were administered in 38% of the cases (281 of 732). Mortality by day 30 was 14% (95% CI, 11 to 16).Management of severe bleeding in patients treated with direct oral anticoagulants appears to be complex. The use of prothrombin complex concentrates differs depending on bleeding sites and direct oral anticoagulant plasma concentrations. Mortality differs according to bleeding sites and was similar to previous estimates.

Background Perioperative activation of hemostasis could play an important role in the occurrence of postoperative cardiac events. The authors conducted a prospective study to assess platelet function, coagulation, and fibrinolysis status during and after infrarenal aortic surgery. Methods Seventeen patients were studied. Excluded were patients with preoperative coagulopathies or liver disease, or cardiac or renal insufficiency; patients receiving anticoagulant treatment, antiplatelet agents, nonsteroidal antiinflammatory agents, fresh frozen plasma, or platelet concentrates; and patients undergoing reoperation and septic patients. Blood samples were drawn before induction (T1), 1 h after incision (T2), 1 h after extubation (T3), 24 h postoperatively (T4), 48 h postoperatively (T5), and at day 7 (T6). The following tests were performed: platelet count, platelet aggregation, platelet flow cytometry for CD62 and CD63, usual coagulation tests, thrombin--antithrombin complexes, plasminogen activator inhibitor 1. Results A significant increase of adenosine diphosphate--induced platelet aggregation was observed postoperatively at T4 and T5. This was not associated with a change of flow cytometry profile. No increase of thrombin--antithrombin complex levels was observed. A higher fibrinogen rate was detected at T5 and T6. Greater amounts of plasminogen activator inhibitor 1 were detected at T3 and T4. Thus, thrombin generation was limited and fibrinolysis was impaired postoperatively. Platelets were not activated in the postoperative period, as shown by flow cytometry, but were prone to be activated, as shown by aggregation studies. Conclusion The association of more easily activated platelets with a higher fibrinogen rate and a temporary shut down of fibrinolysis during the early postoperative period may indicate an increased thrombotic risk in patients undergoing major vascular surgery.

Background A decrease in hematocrit lengthens bleeding time. The authors studied the role of hematocrit variations in an experimental model of arterial thrombosis and bleeding. Methods The Folts model was used in 24 rabbits. After anesthesia was induced and common monitors were positioned, the right common carotid artery was exposed and a 60% stenosis was induced. A compression injury of the artery was then produced, which triggered a series of cyclic episodes of thrombosis and clot lysis (cyclic flow reductions [CFRs]). After counting the number of CFRs that occurred in 20 min (CFR1), the animals were assigned randomly to one of three groups (n = 8 in each group): control, hemodilution with rabbit homologous platelet-rich plasma, and hemodilution with gelatin solution and then reinfusion of the shed blood. The effect of hemodilution with replacement by platelet-rich plasma or by colloid was observed by recording the number of CFRs during another 20-min period (CFR2). A third period of observation (CFR3) followed shed blood reinfusion in the gelatin solution group. Ear immersion bleeding time was recorded after each CFR period. Results In the two experimental groups, the decrease in hematocrit (from 36 +/- 3% to 23 +/- 2% and from 38 +/- 3% to 23 +/- 2%, respectively; mean +/- SD) abolished CFRs (from a median of 4 to 0 and 7 to 0, respectively) and significantly lengthened bleeding time (from 76 +/- 24 s to 114 +/- 36 s and from 84 +/- 37 s to 127 +/- 29 s, respectively). Blood reinfusion in the group that received the gelatin solution caused CFR to reappear (CFR3 = 4). Conclusions Decreases in hematocrit reduced the cyclic arterial thrombosis rate and increased the bleeding time in the rabbits in this study. Hematocrit normalization caused thrombosis to reappear.

Background As a potent anticoagulant agent, rivaroxaban exposes a risk of bleeding. An effective way to reverse its effects is needed. Objectives were to study efficacy and safety of recombinant activated factor VII (rFVIIa) and prothrombin complex concentrate (PCC) to reverse the anticoagulant effect of an overdose of rivaroxaban in a rabbit model of bleeding and thrombosis. Methods First, a dose-ranging study assessed the minimal rivaroxaban dose that increased bleeding. Then, 48 anesthetized and ventilated rabbits were randomized into four groups: control (saline), rivaroxaban (rivaroxaban and saline), rFVIIa (rivaroxaban and rFVIIa), and PCC (rivaroxaban and PCC). The Folts model was applied: a stenosis and an injury were carried out on the carotid artery, inducing thrombosis, detected as cyclic flow reductions, which were recorded over 20 min. Then the following were measured: ear immersion bleeding time, clotting times, anti-Xa activity, thrombelastometric parameters, and thrombin generation test. Ultimately, a hepatosplenic section was performed and the total amount of blood loss after 15 min was evaluated as primary endpoint. Results Rivaroxaban increased blood loss (17 g [8-32] vs. 7 g [5-18] for control (median [range]), P = 0.0004), ear bleeding time, clotting times, thrombelastographic clotting time, and decreased thrombin generation. In contrast, rFVIIa decreased ear bleeding time (92 s [65-115] vs. 140 s [75-190], P < 0.02), but without efficacy on blood loss. PCC and rFVIIa decreased activated partial thromboplastin time as well as thrombelastographic clotting time. Regarding safety, neither rFVIIa nor PCC increased cyclic flow reductions. Conclusion rFVIIa and PCC partially improved laboratory parameters, but did not reverse rivaroxaban induced-bleeding.

Studies have shown that antifibrinolytic (aprotinin, tranexamic acid, epsilon-aminocaproic acid) reduce blood loss in orthopedic surgery. However, most lacked sufficient power to evaluate the efficacy and safety on clinical outcomes. This meta-analysis aims to evaluate whether intravenous antifibrinolytics, when compared with placebo, reduce perioperative allogeneic erythrocyte transfusion requirement in adults undergoing orthopedic surgery and whether it might increase the risk of venous thromboembolism. From MEDLINE, EMBASE, and the Cochrane Controlled Trials Register, the authors identified 43 randomized controlled trials in total hip and knee arthroplasty, spine fusion, musculoskeletal sepsis, or tumor surgery performed to July 2005 (for aprotinin, 23 trials with 1,268 participants; tranexamic acid, 20 with 1,084; epsilon-aminocaproic acid, 4 with 171). Aprotinin and tranexamic acid reduced significantly the proportion of patients requiring allogeneic erythrocyte transfusion according to a transfusion protocol. The odds ratio was 0.43 (95% confidence interval, 0.28-0.64) for aprotinin and 0.17 (0.11-0.24) for tranexamic acid. Results suggest a dose-effect relation with tranexamic acid. Epsilon-aminocaproic acid was not efficacious. Unfortunately, data were too limited for any conclusions regarding safety. Although the results suggest that aprotinin and tranexamic acid significantly reduce allogeneic erythrocyte transfusion, further evaluation of safety is required before recommending the use of antifibrinolytics in orthopedic surgery.

Background Nonsteroidal anti-inflammatory drugs (NSAIDs) may interfere with hemostasis during the perioperative period, and the combination of NSAID and enoxaparin could increase this effect. The aim of this prospective, blinded experimental study was to assess these effects using a model of arterial thrombosis and bleeding in the rabbit. Methods After anesthesia was induced and monitors placed, the common carotid arteries were exposed, and 60% stenosis of the right common carotid artery was produced. Twenty minutes later, a compression injury of the artery was produced that triggered a series of cyclic episodes of thrombosis and clot lysis. This was manifested as cyclic flow reductions (CFR; measured with an electromagnetic flow meter). After the first flow reduction was noted, the rabbits were immediately and randomly assigned to one of four groups (n = 10 each) that received intravenous infusions: control, ketorolac (2 mg/kg), enoxaparin (0.5 mg/kg), and ketorolac plus enoxaparin (2 mg/kg and 0.5 mg/kg, respectively). The number of CFRs that occurred in the subsequent 20-min period was used as a measure of treatment effect. The contralateral common carotid artery was exposed, and both stenosis and injury were produced. The ability of the administered drug to prevent thrombosis was assessed as the number of CFRs that occurred during the first 20-min period after vessel injury. In addition, both before and after group assignment and drug injection, bleeding times were noted and a platelet aggregation test was performed. Laparotomy was followed by a spleen section, and the extent of the wound and the amount of splenic bleeding were measured. Results The treatment effect was indicated by the median number of CFRs, which was 5.5 in the control group, 1 in the ketorolac group, 2 in the enoxaparin group, and 0 in the ketorolac + enoxaparin group. The prevention effect was indicated by the median number of CFRs, which was 4 in the control group, 0 in the ketorolac group, 2 in the enoxaparin group, and 0.5 in the ketorolac + enoxaparin group. Bleeding time was significantly lengthened in the enoxaparin and in the ketorolac + enoxaparin groups. Splenic and wound bleeding was greater in the ketorolac group. Platelet aggregation was completely inhibited in the ketorolac and the ketorolac + enoxaparin groups. Conclusions Ketorolac had an important antithrombotic activity. The association of enoxaparin with ketorolac seemed to lengthen the bleeding time observed with ketorolac.