Successful control of postsurgical bleeding by recombinant factor VIIa in a renal failure patient given low molecular weight heparin and aspirin

A Historical Perspective on the Reversal of Anticoagulants

There has been a landmark shift in the last several decades in the management and prevention of thromboembolic events. From the discovery of parenteral and oral agents requiring frequent monitoring as early as 1914, to the development of direct oral anticoagulants (DOACs) that do not require monitoring or dose adjustment in the late 20th century, great advances have been achieved. Despite the advent of these newer agents, bleeding continues to be a key complication, affecting 2 to 4% of DOAC-treated patients per year. Bleeding is associated with substantial morbidity and mortality. Although specific reversal agents for DOACs have lagged the release of these agents, idarucizumab and andexanet alfa are now available as antagonists. However, the efficacy of these reversal agents is uncertain, and complications, including thrombosis, have not been adequately explored. As such, guidelines continue to advise the use of nonspecific prohemostatic agents for patients requiring reversal of the anticoagulant effect of these drugs. As the indications for DOACs and the overall prevalence of their use expand, there is an unmet need for further studies to determine the efficacy of specific compared with nonspecific pro-hemostatic reversal agents. In this review, we will discuss the evidence behind specific and nonspecific reversal agents for both parenteral and oral anticoagulants.

Treatment of bleeding complications in patients on anticoagulant therapy

Anticoagulant therapy is often refrained from out of fear of hemorrhagic complications. The most frequent type of major bleeding is gastrointestinal, but intracranial hemorrhage has the worst prognosis. Management of these complications in patients on anticoagulants should follow the same routines as for nonanticoagulated patients, as described here with the previously mentioned bleeds as examples. In addition, for life-threatening or massive hemorrhages, reversal of the anticoagulant effect is also crucial. Adequate reversal requires information on which anticoagulant the patient has taken and when the last dose was ingested. Laboratory data can be of some help, but not for all anticoagulants in the emergency setting. This is reviewed here for the different types of anticoagulants: vitamin K antagonists, heparins, fondaparinux, thrombin inhibitors and factor Xa inhibitors. Specific antidotes for the latter are becoming available, but supportive care and nonspecific support for hemostasis with antifibrinolytic agents or prothrombin complex concentrates, which are widely available, should be kept in mind.

Major publications in the critical care pharmacotherapy literature: January-December 2016

PURPOSE

To summarize select critical care pharmacotherapy guidelines and studies published in 2016.

SUMMARY

The Critical Care Pharmacotherapy Literature Update (CCPLU) Group screened 31 journals monthly for relevant pharmacotherapy articles and selected 107 articles for review over the course of 2016. Of those included in the monthly CCPLU, three guidelines and seven primary literature studies are reviewed here. The guideline updates included are as follows: hospital-acquired pneumonia and ventilator-associated pneumonia management, sustained neuromuscular blocking agent use, and reversal of antithrombotics in intracranial hemorrhage (ICH). The primary literature summaries evaluate the following: dexmedetomidine for delirium prevention in post-cardiac surgery, dexmedetomidine for delirium management in mechanically ventilated patients, high-dose epoetin alfa after out-of-hospital cardiac arrest, ideal blood pressure targets in ICH, hydrocortisone in severe sepsis, procalcitonin-guided antibiotic de-escalation, and empiric micafungin therapy.

CONCLUSION

The review provides a synopsis of select pharmacotherapy publications in 2016 applicable to clinical practice.

Intentional overdose with tinzaparin: management dilemmas

BACKGROUND

Low-molecular-weight heparin (LMWH) is increasingly being prescribed for prophylaxis and treatment of thromboembolic diseases. Despite the fact that its therapeutic use is considered to be safe, it can be complicated by major hemorrhage and, in contrast to unfractionated heparin, it can only partially be neutralized by protamine. Recent reports of LMWH overdose illustrate the need for a consensus on its management.

OBJECTIVES

To describe a case of self-poisoning with a very large dose of tinzaparin and discuss management options in patients with LMWH overdose.

CASE REPORT

A 69-year-old woman was brought to the Emergency Department 2 h after injecting herself with 280,000 IU of tinzaparin subcutaneously in an attempt to commit suicide. Despite an unrecordable activated partial thromboplastin time (APTT > 180 s) and prolonged prothrombin time, there was no evidence of active bleeding. She was given an intravenous infusion of 100 mg protamine sulfate and was admitted to the intensive care unit, where further infusions of protamine were administered. Normalization of the APTT occurred 40-50 h post admission, reflecting normal tinzaparin clearance rather than neutralization by protamine. No hemorrhagic complications occurred during her hospitalization except for prolonged bleeding from venipuncture sites.

CONCLUSION

In this case of massive tinzaparin overdose, conventional doses of protamine failed to rapidly normalize the deranged coagulation parameters. The favorable clinical outcome suggests that, regardless of the LMWH amount injected, no active treatment is needed in the absence of hemorrhage. This is in accordance with the limited published data concerning cases of overdose with other LMWHs.

Recombinant Activated Factor VII in Patients at High Risk of Bleeding

Currently, recombinant activated factor VII (rFVIIa) (NovoSeven) is indicated for the treatment of spontaneous and surgical bleeding in congenital haemophilia A and B patients with inhibitors to factors VIII (FVIII) and IX (FIX) >5 Bethesda units (BU) worldwide, and in patients with acquired haemophilia, congenital FVII deficiency and Glanzmann's thrombasthenia in Europe. Until April 2003, almost three-quarters of a milion doses of rFVIIa have been administered proving its efficacy and excellent safety record. According to results from initial clinical trials and a large number of case reports, the rFVIIa may be effective not only in treating haemophilia patients but also in treatment of bleeding in patients on oral anticoagulation or heparin, patients with liver diseases, von Willebrand disease (vWD), thrombocytopenia, various platelet defects, congenital or acquired deficiency of FVII, and in subjects without any pre-existing coagulopathy with diffuse life-threatening bleeding triggered by surgery or trauma. This review will briefly summarize rFVIIa mode of action in haemostasis, the current clinical experience with rFVIIa and focus on the alternative use of rFVIIa in patients at the high risk of bleeding in both spontaneous cases and clinical trials reports.

Treatment of bleeding after kidney biopsy with recombinant activated factor VII

Recombinant activated factor VII (rFVIIa) is approved for prevention and treatment of bleeding in hemophilia patients with inhibitors to FVIII (hemophilia A) or IX (hemophilia B), patients with congenital and acquired hemophilia and in patients with FVII deficiency or Glantzmann thrombasthenia (last indication is approved only in Europe). Off-labeled, the drug has been prescribed for prevention, or treatment of bleeding in severe hepatic disease, neonatal coagulopathies, high-risk surgical procedures, trauma, thrombocytopenia and platelet function disorders, as well as for urgent reversal of oral anticoagulation. Here we report a case of a 53-year-old female patient with delayed graft function after kidney transplantation, who had kidney biopsy complicated with prolonged bleeding. After unsuccessful treatment with desmopressin, the patient was treated with rFVIIa and the bleeding stopped immediately. Only few anecdotal reports of use of rFVIIa for treatment of bleeding in uremic patients have been published thus far. To our knowledge, this is the first case that describes use of rFVIIa for management of bleeding as a complication of renal biopsy in a uremic patient in the early kidney posttransplantation period.

Management of bleeding complications in the anticoagulated patient

As new anticoagulants become available, and the number of anticoagulated patients continues to rise, it is necessary to know how to deal with associated bleeding complications. In this review, reversal strategies for traditional anticoagulants (warfarin and heparin) as well as newer anticoagulants are described. Prothrombin complex concentrates (PPCs) can be used to reverse vitamin K antagonists (VKA), and plasma may be used where they are not available. Recombinant activated factor VII (rFVIIa) may be useful to reverse pentasaccharide anticoagulants. 1-Desamino-8-D-arginine vasopressin (DDAVP), cryoprecipitate, PCCs, and dialysis may help to reverse direct thrombin inhibitors, while rFVIIa seems to be ineffective. The effect of direct factor Xa inhibitors may be reversed by PCCs, FVIIa, or factor Xa concentrates.

Parenteral anticoagulants: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

This article describes the pharmacology of approved parenteral anticoagulants. These include the indirect anticoagulants, unfractionated heparin (UFH), low-molecular-weight heparins (LMWHs), fondaparinux, and danaparoid, as well as the direct thrombin inhibitors hirudin, bivalirudin, and argatroban. UFH is a heterogeneous mixture of glycosaminoglycans that bind to antithrombin via a unique pentasaccharide sequence and catalyze the inactivation of thrombin, factor Xa, and other clotting enzymes. Heparin also binds to cells and plasma proteins other than antithrombin causing unpredictable pharmacokinetic and pharmacodynamic properties and triggering nonhemorrhagic side effects, such as heparin-induced thrombocytopenia (HIT) and osteoporosis. LMWHs have greater inhibitory activity against factor Xa than thrombin and exhibit less binding to cells and plasma proteins than heparin. Consequently, LMWH preparations have more predictable pharmacokinetic and pharmacodynamic properties, have a longer half-life than heparin, and are associated with a lower risk of nonhemorrhagic side effects. LMWHs can be administered once daily or bid by subcutaneous injection, without coagulation monitoring. Based on their greater convenience, LMWHs have replaced UFH for many clinical indications. Fondaparinux, a synthetic pentasaccharide, catalyzes the inhibition of factor Xa, but not thrombin, in an antithrombin-dependent fashion. Fondaparinux binds only to antithrombin. Therefore, fondaparinux-associated HIT or osteoporosis is unlikely to occur. Fondaparinux exhibits complete bioavailability when administered subcutaneously, has a longer half-life than LMWHs, and is given once daily by subcutaneous injection in fixed doses, without coagulation monitoring. Three additional parenteral direct thrombin inhibitors and danaparoid are approved as alternatives to heparin in patients with HIT.

Protamine reversal of low molecular weight heparin: clinically effective?

Low molecular weight heparins (LMWHs) are frequently used in the prophylaxis or treatment of venous thrombosis, acute coronary syndromes and peri-operative bridging. Major bleeding occurs in 1-4% depending on dose and underlying condition. Protamine is recommended for reversal but only partially reverses the anti-Xa activity and there are very limited data on clinical effectiveness. We retrospectively studied the effect of emergency reversal of LMWH with protamine in actively bleeding patients and patients requiring emergency surgery in our institution. Eighteen patients were identified through haematology referral/pharmacy records of protamine prescriptions between 1998 and 2009. Case notes were checked for the reversal indication, type/dose of LMWH, dose and clinical response to protamine, timing in relation to the last dose of LMWH and anti-Xa levels before and after protamine. All but one patient received enoxaparin. Fourteen were actively bleeding, three required emergency surgery without active bleeding and one had an accidental overdose without bleeding. The three patients requiring surgery had an uneventful procedure. In 12 of 14 patients with active bleeding, protamine could be evaluated. Bleeding stopped in eight. In the four with continuing bleeding, one had an additional coagulopathy. Protamine only partially affected anti-Xa levels. Protamine may be of use in reversing bleeding associated with LMWH but not in all patients. Anti-Xa levels were useful to assess the amount of anticoagulation before protamine administration but unhelpful in assessing its effect. Better reversal agents and methods to monitor LMWH therapy are required.

Neutralization of heparin activity

Heparin is the mainstay in the treatment and prevention of thrombosis in such diverse clinical settings as venous thromboembolism, acute coronary syndrome, cardiopulmonary bypass, and hemodialysis. However, the major complication of heparin - like that of all anticoagulants - is bleeding. Heparin may need to be reversed in the following settings: clinically significant bleeding; prior to an invasive procedure; at the conclusion of a procedure involving extracorporeal circulation (e.g., cardiopulmonary bypass, dialysis). This chapter discusses protamine sulfate, as well as several other agents that are able to neutralize heparin, including their pharmacological properties, indications, dosing, and efficacy.

Low-Molecular-Weight Heparin Overdose: Management by Observation

Objective:

To describe 3 episodes of low-molecular-weight heparin (LMWH) overdose in 2 patients and discuss the clinical presentations, outcomes, and therapeutic options.

Case Summaries:

The first patient, a 35-year-old female, presented after an intentional overdose of 72,000 units of dalteparin. The peak measured anti-Xa activity was 6.2 U/mL at 7.5 hours postinjection. No interventions were performed and there were no bleeding complications. The patient presented 20 days later following another overdose of 72,000 units. Anti-Xa activity was 4.5 U/mL 2 hours postinjection. No treatment was given and the patient was discharged with plans for follow-up the next day. There was no evidence of bleeding complications on follow-up. The second patient, a 29-year-old male, presented after an intentional overdose of 480 mg of enoxaparin. The anti-Xa activity was 1.9 U/mL measured 2 hours postinjection. The patient was observed without intervention. There were no bleeding complications.

Discussion:

To our knowledge, there is only one previous report of an LMWH overdose in the literature, an iatrogenic overdose in an infant treated with protamine. In our 3 presented episodes of LMWH overdose, no therapeutic interventions were performed and there were no bleeding complications. Review of the literature regarding the efficacy of protamine and recombinant factor VIIa for reversal of LMWH coagulopathy revealed that protamine is only partially effective and recombinant factor VIIa is effective in in vitro studies and case reports.

Conclusions:

In cases of LMWH overdose, observation seems to be appropriate in the absence of clinically significant bleeding. Prolonged monitoring may be necessary for patients with renal failure. Use of protamine or recombinant factor VIIa is not supported by this case series in patients without significant bleeding. There is a lack of data regarding how to treat patients with significant bleeding.

Controversies of Anticoagulation Reversal in Life-Threatening Bleeds

Therapeutic anticoagulation with heparins, warfarin, and anti-Xa inhibitors carry an inherent risk of complications due to their multifaceted pharmacokinetic and pharmacodynamic properties as well as narrow therapeutic ranges. When an anticoagulated patient presents with a major or life-threatening bleed, immediate and effective therapy may be necessary to reverse the effects of the anticoagulant, minimize blood loss, and reduce patient morbidity and mortality. Optimal agents and strategies for anticoagulant reversal are limited, particularly for newer anticoagulants. The literature describing such strategies available to reverse the effects of anticoagulants in the setting of a bleed is limited, and therefore many controversies exist. Thus, as new anticoagulants become available, without a specific agent for reversal, the concerns and controversies related to this topic must be addressed. The purpose of this review is to discuss the management of major or life-threatening bleeds by addressing the following controversies: (1) the use of recombinant factor VIIa for rapid reversal of warfarin in patients with intracerebral hemorrhage, (2) the role of prothrombin complex concentrate in emergent warfarin reversal, and (3) the optimal approach to reverse newer anticoagulants such as low molecular weight heparins, fondaparinux, and direct thrombin inhibitors.

Treatment of bleeding in dialysis patients

Bleeding is a common and potentially serious complication of acute and chronic renal failure. The pathogenesis of bleeding in uremia is multifactorial; however, the major role is played by abnormalities in platelet-platelet and platelet-vessel wall interaction. Platelet dysfunction is partially due to uremic toxins present in circulating blood. Despite decreased platelet function, abnormalities of blood coagulation and fibrinolysis predispose the uremic patients to a hypercoagulable state carrying the risk of cardiovascular and thrombotic complications. Dialysis improves platelet abnormalities and reduces, but does not eliminate, the risk of hemorrhage. Hemodialysis can even contribute to the bleeding through the continuous platelet activation induced by the interaction between blood and artificial surfaces and the use of anticoagulants. Correction of anemia improves hemostasis in uremic patients. Therapeutic management of bleeding in patients with uremia is discussed.

Management of bleeding and of invasive procedures in patients with platelet disorders and/or thrombocytopenia: Guidelines of the Italian Society for Haemostasis and Thrombosis (SISET)

The optimal management of bleeding or its prophylaxis in patients with disorders of platelet count or function is controversial. The bleeding diathesis of these patients is usually mild to moderate: therefore, transfusion of platelet concentrates may be inappropriate, as potential adverse effects might outweigh its benefit. The availability of several anti-hemorrhagic drugs further compounds this problem, mainly because the efficacy/suitability of the various treatment options in different clinical manifestations is not well defined. In these guidelines, promoted by the Italian Society for Studies on Haemostasis and Thrombosis (Società Italiana per lo Studio dell'Emostasi e della Trombosi [SISET]), we aim at offering the best available evidence to help the physicians involved in the management of patients with disorders of platelet count or function. Literature review and appraisal of available evidence are discussed for different clinical settings and for different available treatments, including platelet concentrates (PC), recombinant activated factor VII, desmopressin, antifibrinolytics, aprotinin and local hemostatic agents.

Recombinant human factor VIIa and a factor VIIa-analogue reduces heparin and low molecular weight heparin (LMWH)-induced bleeding in rats

BACKGROUND

Heparin and low molecular weight heparin (LMWH) are widely used for prevention and treatment of thromboemobolic events, but may occasionally cause uncontrollable bleeding. Heparin can readily be antagonized with protamine, but this is less effective against LMWH.

OBJECTIVES

To test the effects of rFVIIa or an analogue of rFVIIa, NN1731, on heparin- and LMWH-induced bleeding in rats.

METHODS

Initially the doses of heparin and tinzaparin (a LMWH) were determined by dose-titration. Following pretreatment with heparin or tinzaparin in rats, tail-transection was performed, and the effect of rFVIIa and NN1731 on the bleeding was observed.

RESULTS

rFVIIa (5, 10 and 20 mg kg(-1)) reduced bleeding time and blood loss caused by heparin- and tinzaparin-induced bleeding, using doses of 200 IU kg(-1) (n = 8) and 500 IU kg(-1) (n = 9), respectively. Similarly, 10 mg kg(-1) NN1731 significantly reduced both heparin- and tinzaparin-induced bleeding to the normal level. Following severe anticoagulation with 1800 IU kg(-1) tinzaparin, 10 mg kg(-1) NN1731 reduced and normalized the bleeding, while the effect of 20 mg kg(-1) rFVIIa failed to reach statistical significance. These data are consistent with the hypothesis that rFVIIa/NN1731 are capable of generating sufficient thrombin locally on the surface of activated platelets to induce hemostasis in the presence of heparin/LMWH.

CONCLUSIONS

This study suggests that rFVIIa and NN1731 may have the potential to control bleedings caused by heparin or LMWH.

Use of recombinant activated factor VII to arrest uncontrolled bleeding: a case series

A retrospective analysis is described to assess the effects of using recombinant activated factor VII to control bleeding in a series of patients who had failed to respond to conventional hemostatic measures. In all, 18 patients (aged 16-65 years) with a range of conditions resulting in bleeding refractory to conventional methods of control were treated with recombinant activated factor VII (60-120 Amicrog/kg; 1-4 doses). The effects of recombinant activated factor VII on bleeding were noted together with the patients' transfusion requirements and hematological parameters. Administration of recombinant activated factor VII successfully stopped bleeding in 17 of the 18 patients. Therapy with recombinant activated factor VII significantly decreased transfusion requirements for packed red blood cells, fresh frozen plasma, platelets, and cryoprecipitate compared with pretreatment values along with significant improvement in hemostasis. In various serious bleeding situations, treatment with recombinant activated factor VII may effectively arrest bleeding, which has remained refractory to conventional methods of control.

Successful management of bleeding with recombinant factor VIIa (NovoSeven) in a patient with Burkitt lymphoma and thrombosis of the left femoral and left common iliac veins

We present the case of an 18-year-old female with Burkitt lymphoma involving the intra-abdominal and inguinal lymph nodes. The tumor had invaded the left femoral and common iliac veins causing secondary thrombosis and vessel occlusion. Chemotherapy and anticoagulant treatment resulted in mild thrombocytopenia and a prolonged prothrombin time, respectively, which exacerbated postoperative bleeding following surgical removal of a deep inguinal necrosis. After 6 days, bleeding combined with epistaxis was considered to be life threatening and anticoagulant reversal with recombinant factor VIIa was successfully performed. The patient has since achieved complete remission and subsequent antithrombotic therapy has resolved the vascular occlusion.

Perioperative blood transfusion and blood conservation in cardiac surgery: the Society of Thoracic Surgeons and The Society of Cardiovascular Anesthesiologists clinical practice guideline

BACKGROUND

A minority of patients having cardiac procedures (15% to 20%) consume more than 80% of the blood products transfused at operation. Blood must be viewed as a scarce resource that carries risks and benefits. A careful review of available evidence can provide guidelines to allocate this valuable resource and improve patient outcomes.

METHODS

We reviewed all available published evidence related to blood conservation during cardiac operations, including randomized controlled trials, published observational information, and case reports. Conventional methods identified the level of evidence available for each of the blood conservation interventions. After considering the level of evidence, recommendations were made regarding each intervention using the American Heart Association/American College of Cardiology classification scheme.

RESULTS

Review of published reports identified a high-risk profile associated with increased postoperative blood transfusion. Six variables stand out as important indicators of risk: (1) advanced age, (2) low preoperative red blood cell volume (preoperative anemia or small body size), (3) preoperative antiplatelet or antithrombotic drugs, (4) reoperative or complex procedures, (5) emergency operations, and (6) noncardiac patient comorbidities. Careful review revealed preoperative and perioperative interventions that are likely to reduce bleeding and postoperative blood transfusion. Preoperative interventions that are likely to reduce blood transfusion include identification of high-risk patients who should receive all available preoperative and perioperative blood conservation interventions and limitation of antithrombotic drugs. Perioperative blood conservation interventions include use of antifibrinolytic drugs, selective use of off-pump coronary artery bypass graft surgery, routine use of a cell-saving device, and implementation of appropriate transfusion indications. An important intervention is application of a multimodality blood conservation program that is institution based, accepted by all health care providers, and that involves well thought out transfusion algorithms to guide transfusion decisions.

CONCLUSIONS

Based on available evidence, institution-specific protocols should screen for high-risk patients, as blood conservation interventions are likely to be most productive for this high-risk subset. Available evidence-based blood conservation techniques include (1) drugs that increase preoperative blood volume (eg, erythropoietin) or decrease postoperative bleeding (eg, antifibrinolytics), (2) devices that conserve blood (eg, intraoperative blood salvage and blood sparing interventions), (3) interventions that protect the patient's own blood from the stress of operation (eg, autologous predonation and normovolemic hemodilution), (4) consensus, institution-specific blood transfusion algorithms supplemented with point-of-care testing, and most importantly, (5) a multimodality approach to blood conservation combining all of the above.

Recombinant Factor VIIa Reduces Bleeding Risk in Patients on Platelet Aggregation Inhibitors Immediately prior to Renal Transplantation – A Retrospective Analysis

BACKGROUND

Transplant surgery often requires an effective preoperative treatment which allows to reduce the risk of bleeding caused by platelet aggregation inhibitors without major delay. The use of recombinant activated coagulation factor VIIa (rFVIIa) may be a future treatment option in such patients.

METHOD

Five patients with end-stage renal disease on treatment with platelet aggregation inhibitors (ASA, Plavix, Aggrenox), who were scheduled for renal transplantation and received a preoperative bolus of recombinant factor VIIa (rFVIIa, NovoSeven) in a dose of 3 kIU/kg (60 microg/kg), were retrospectively analyzed. Parameters of plasmatic coagulation as well as bleeding time were determined before as well as after the administration of rFVIIa.

RESULTS

The initial median bleeding time was 7.3 min (range 6.2-14.6); after administration of rFVIIa it fell to 2.8 min (range 1.8-3.2). All patients had a good intraoperative hemostasis. None of the patients developed a hematoma requiring surgical treatment. The graft of all patients was homogeneously and well perfused, with a sufficient postoperative diuresis.

CONCLUSION

The administration of rFVIIa prior to renal transplantation in patients on treatment with platelet aggregation inhibitors was effective and without major complications. Further studies should be performed in order to confirm our observations.

Successful use of recombinant factor VIIa (NovoSeven) in children with compartment syndrome: two case reports

Compartment syndrome (CS) is an uncommon bleeding manifestation in patients with liver failure and end-stage renal disease (ESRD). Although prompt intervention is paramount in preventing the tissue necrosis and the permanent functional deficits that may be associated with untreated CS, the indications for initiating therapies for children with CS are not standardized. In this report, we present 2 children, one with ESRD and the other with liver failure, who have CS related to life-threatening bleeding complications and were treated with recombinant factor VIIa (rFVIIa). In conclusion, treatment decisions for patients with CS should be made on a case-by-case basis. The use of rFVIIa is an effective and safe treatment in children with liver failure and ESRD. Surgical treatment should be preferred in patients with CS. However, in patients who have a coagulation defect, the first priority is to correct the clotting deficiency. The use of rFVIIa is a treatment option in children with CS due to a coagulation defect.

Recommendations on the use of recombinant activated factor VII as an adjunctive treatment for massive bleeding--a European perspective

Introduction

Our aim was to develop consensus guidelines for use of recombinant activated factor VII (rFVIIa) in massive hemorrhage.

Methods

A guidelines committee derived the recommendations using clinical trial and case series data identified through searches of available databases. Guidelines were graded on a scale of A to E (with A being the highest) according to the strength of evidence available. Consensus was sought among the committee members for each recommendation.

Results

A recommendation for the use of rFVIIa in blunt trauma was made (grade B). rFVIIa might also be beneficial in post-partum hemorrhage (grade E), uncontrolled bleeding in surgical patients (grade E), and bleeding after cardiac surgery (grade D). rFVIIa could not be recommended for use in the following: in penetrating trauma (grade B); prophylactically in elective surgery (grade A) or liver surgery (grade B); or in bleeding episodes in patients with Child–Pugh A cirrhosis (grade B). Efficacy of rFVIIa was considered uncertain in bleeding episodes in patients with Child–Pugh B and C cirrhosis (grade C). Monitoring of rFVIIa efficacy should be performed visually and by assessment of transfusion requirements (grade E), while thromboembolic adverse events are a cause for concern. rFVIIa should not be administered to patients considered unsalvageable by the treating medical team.

Conclusion

There is a rationale for using rFVIIa to treat massive bleeding in certain indications, but only adjunctively to the surgical control of bleeding once conventional therapies have failed. Lack of data from randomized, controlled clinical trials, and possible publication bias of the case series data, limits the strength of the recommendations that can be made.

Reversal of low-molecular-weight heparin-induced bleeding in patients with pre-existing hypercoagulable states with human recombinant activated factor VII concentrate

Low-molecular-weight heparins are widely employed in prophylactic and therapeutic antithrombotic regimens for venous thromboembolic events. Excessive anticoagulation with low-molecular-weight heparins rarely can precipitate catastrophic bleeding complications. Currently, there is no specific or reliable antidote that can reverse the anticoagulant effects of low-molecular-weight heparins efficiently and safely. This report describes three individuals with underlying hypercoagulable states, who developed clinically significant bleeding complications while receiving therapeutic anticoagulation with enoxaparin. All of the hemorrhagic events subsequently were safely and effectively reversed with a single intravenous bolus infusion of recombinant activated factor VIIa (RFVIIa) concentrate. Hemoglobins, prothrombin times, and clinical overt bleeding were monitored before and after the administration of RFVIIa. In all three cases, bleeding was controlled without an increase in thrombotic events. Our findings demonstrate that RFVIIa can rapidly and safely reverse the hemorrhagic adverse effects associated with excessive levels of low-molecular-weight heparin in patients with pre-existing hypercoagulable conditions and/or acute venous thromboembolism.

HEMATOLOGY: ISSUES IN THE DIALYSIS PATIENT: Anticoagulation and Continuous Renal Replacement Therapy

More than half of patients with acute renal failure in the intensive care unit require dialysis, and the majority of them have significant hemodynamic instability. Continuous renal replacement therapy (CRRT) is often the preferred dialysis modality in these patients. One requirement for CRRT is anticoagulation, which can expose patients to the risk of bleeding. However, absence of effective anticoagulation may result in clotting of the CRRT circuit and subsequently less effective treatment. While heparins are widely used for anticoagulation, because of potential side effects such as bleeding and heparin-induced thrombocytopenia, alternative anticoagulation protocols should be considered. Citrate anticoagulation, regional heparin/protamine, predilution, r-hirudin, prostacyclin, and nafamostat are among these methods.

Management of venous thromboembolism in patients with primary and metastatic brain tumors

Venous thromboembolism occurs commonly throughout the clinical course of patients with brain tumors. A number of hemostatic and clinical factors contribute to this hypercoagulable state. Concern over the possibility of intracranial bleeding has limited the use of anticoagulation in this population. However, mechanical approaches such as vena cava filters have high complication and treatment failure rates in patients with intracranial malignancies. In addition, the available data suggest that anticoagulation can be used safely and effectively in most of these patients. Patients with thrombocytopenia, recent neurosurgery, and tumor types prone to bleeding require special consideration. When intracranial hemorrhage does occur, it is often due to overanticoagulation, requiring prompt anticoagulation reversal and neurosurgical consultation.

Bleeding in Cardiac Surgery: Its Prevention and Treatment—an Evidence-Based Review

Expected and unexpected bleeding occur frequently in patients undergoing cardiac surgery. Bleeding after cardiac surgery can be broadly divided into two groups: surgical (unrecognized bleeding vessel, anastomosis, or other suture line) or nonsurgical bleeding (caused by coagulopathy). Factors influencing both surgical and nonsurgical bleeding can be further broken down into those occurring preoperatively and those that occur intraoperatively and postoperatively. A thorough understanding of these factors is necessary to reduce bleeding. This is a desirable clinical goal, because excessive bleeding is associated with adverse outcomes.

Venous Thromboembolism in the ICU and Reversal of Bleeding on Anticoagulants

Venous thromboembolic disease is a very common complication in the ICU. This article reviews incidence, prevention, and therapy related to venous thromboembolism, including both deep venous thrombosis and pulmonary embolism. Special diagnostic and treatment considerations in the ICU setting are highlighted. The increased use of antithrombotic agents has led to an increased number of patients who experience bleeding complications on anticoagulant therapy. This review also addresses the methods of reversing various anticoagulants.

Successful reversal of anticoagulant effect of superwarfarin poisoning with recombinant activated factor VII

The use of second-generation anticoagulants termed "superwarfarins" as rodenticides, although widespread, is poorly controlled. Products containing superwarfarin have been marketed in over-the-counter rodenticides and can be easily purchased. Poor control potentiates the risk of accidental or intentional poisoning, but clinicians may underestimate the incidence of superwarfarin toxicity. Therefore, when cases of unexplained acquired coagulopathy and selective deficiency of vitamin K-dependent clotting factors occur in patients in the absence of liver disease or inhibitors, physicians should consider the possibility of superwarfarin poisoning as a cause. According to our own experience, recombinant activated factor VII (NovoSeven; Novo Nordisk, Bagsvaerd, Denmark) appears to be a safe and effective therapy for acute bleeding caused by superwarfarin poisoning. Due to the extended half-life of the second-generation rodenticides, follow-up therapy with oral vitamin K1 should be of long-term duration.

A Review of Recombinant Factor VII for Refractory Bleeding in Nonhemophilic Trauma Patients

BACKGROUND

Recombinant factor VII (rFVII) is an attractive agent to control refractory, coagulopathic bleeding in patients following major surgery. The purpose of this review is to evaluate the published experiences of rFVII in adult, nonhemophilic, surgical and trauma patients.

METHODS

A computerized literature search was conducted to identify articles pertaining to rFVII use for refractory bleeding in adult, nonhemophilic, surgical patients. The selected articles were reviewed and the applicable data was analyzed.

RESULTS

A total of 117 patients were found in 8 case series and 24 case reports. Overall, rFVII was effective in restoring hemostasis in 99/117 (85%) patients with 76/99 (77%) surviving to hospital discharge. In trauma patients, hemostasis was achieved in 20/26 (77%) patients and 17/20 (85%) survived. There were 5 (4%) thromboembolic events observed in the 117 cases and much disparity was noted with the initial dose. Severe acidosis affected the activity of rFVII.

CONCLUSION

Recombinant factor VII is an effective therapeutic agent for achieving hemostasis in nonhemophilic surgical patients. Published clinical experiences, however, are limited to small case series and case reports.

Heparin and Low-Molecular-Weight Heparin

This article about unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) is part of the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. UFH is a heterogeneous mixture of glycosaminoglycans that bind to antithrombin via a pentasaccharide, catalyzing the inactivation of thrombin and other clotting factors. UFH also binds endothelial cells, platelet factor 4, and platelets, leading to rather unpredictable pharmacokinetic and pharmacodynamic properties. Variability in activated partial thromboplastin time (aPTT) reagents necessitates site-specific validation of the aPTT therapeutic range in order to properly monitor UFH therapy. Lack of validation has been an oversight in many clinical trials comparing UFH to LMWH. In patients with apparent heparin resistance, anti-factor Xa monitoring may be superior to measurement of aPTT. LMWHs lack the nonspecific binding affinities of UFH, and, as a result, LMWH preparations have more predictable pharmacokinetic and pharmacodynamic properties. LMWHs have replaced UFH for most clinical indications for the following reasons: (1) these properties allow LMWHs to be administered subcutaneously, once daily without laboratory monitoring; and (2) the evidence from clinical trials that LMWH is as least as effective as and is safer than UFH. Several clinical issues regarding the use of LMWHs remain unanswered. These relate to the need for monitoring with an anti-factor Xa assay in patients with severe obesity or renal insufficiency. The therapeutic range for anti-factor Xa activity depends on the dosing interval. Anti-factor Xa monitoring is prudent when administering weight-based doses of LMWH to patients who weigh > 150 kg. It has been determined that UFH infusion is preferable to LMWH injection in patients with creatinine clearance of < 25 mL/min, until further data on therapeutic dosing of LMWHs in renal failure have been published. However, when administered in low doses prophylactically, LMWH is safe for therapy in patients with renal failure. Protamine may help to reverse bleeding related to LWMH, although anti-factor Xa activity is not fully normalized by protamine. The synthetic pentasaccharide fondaparinux is a promising new antithrombotic agent for the prevention and treatment of venous thromboembolism.

Antidotes to haemorrhage: recombinant factor VIIa

Recombinant Factor VIIa (rFVIIa) concentrates were originally developed to treat the refractory bleeding complications associated with allo-antibody inhibitors in hemophilias A and B. As experience was gained in the hemophilias, the physiology of rFVIIa and its successes in controlling bleeds stimulated rFVIIa use in other challenging medical conditions complicated by bleeding. Thus, rFVIIa has assumed the role of a 'universal pancoagulant' without sufficient evidence-based data from well-designed, adequately powered clinical trials. This chapter discusses the anecdotal experience with rFVIIa based upon the few controlled trials that do exist, and emphasizes that these empirical dosing strategies have not yielded the best approach to achieve effective control of bleeding. Evidence-based data are necessary to establish the cost-benefit and risk-benefit profiles of rFVIIa, and to establish it as a standard treatment for bleeding.

Novel hemostatic alternatives in reconstructive surgery

Congenital vascular lesions are classed as hemangiomas, vascular malformations, or vascular tumors according to their histology and etiology. The majority of hemangiomas are benign and often involute before the child reaches the age of 12. Severe hemangiomas and vascular malformations were historically viewed as effectively inoperable due to the high risk of potentially catastrophic bleeding during surgery. An effective system of classification and increasing range of therapeutic options have improved the prognosis for many patients, but surgical resection of these lesions remains a serious undertaking. Topical hemostatic agents are widely used and effective in many cases for the control of intraoperative bleeding. The main limitations of these agents are their variability and lack of efficacy in severe bleeding, or in coagulopathic or anticoagulant-treated patients. This paper reviews recent developments in this field, including the possible placental origin of hemangiomas, and discusses current approaches to hemostasis during reconstructive surgery. We also discuss the recent introduction of recombinant activated factor VII (rFVIIa) as a systemic hemostatic agent, including our own experience using this treatment.

Recombinant factor VIIa (rFVIIa) and its use in severe bleeding in surgery and trauma: a review

Haemorrhage is a potential complication of any surgical procedure, presenting a major challenge to the surgeon and anaesthetist. In addition, uncontrolled bleeding accounts for at least 40% of the mortality associated with military and civilian trauma. Despite the widespread availability of standard interventions for the control of bleeding in such circumstances, there still remains an urgent need for an effective haemostatic agent that is safe, easy to use, and able to enhance local thrombotic processes without causing generalised arterial or venous thrombosis. Recombinant factor VIIa (rFVIIa; NovoSeven) has been successfully used in the management of haemophilia patients with inhibitors for many years. This review will explore its use in the control of surgery- and trauma-associated haemorrhage in patients without pre-existing coagulopathy, and will highlight the growing realisation that rFVIIa may have a major role not only as a treatment for haemophilia, but also as a universal haemostatic agent. This paper will also briefly explore those unanswered questions that should be resolved by future trials aiming to further clarify the safety, efficacy, and optimal dosing strategies of rFVIIa in the surgical and trauma settings.