Recombinant activated factor VII increases survival time in a model of incompressible arterial hemorrhage in the anesthetized pig

BACKGROUND

Hemorrhage is the leading cause of death in battlefield casualties and the second leading cause of death after civilian trauma. Evacuation time for military casualties to surgical care can be prolonged and improved hemostasis could greatly reduce mortality. There are several anecdotal reports that recombinant activated factor VII (rFVIIa) may arrest uncontrolled bleeding after trauma. However, the majority of prospective randomized controlled trials show little benefit in survival. The aim of this study was to determine whether rFVIIa could increase survival time within a clinically relevant time scale for military practice and reduce the volume of blood loss in a model of incompressible arterial hemorrhage. A secondary aim was to determine the effects of hypotensive versus normotensive resuscitation on the effectiveness of rFVIIa.

METHODS

Terminally anaesthetized Large White pigs were randomly allocated to one of four treatment groups. All animals received a controlled hemorrhage of 40% of the total estimated blood volume. They were given either rFVIIa (180 microg/kg) or placebo (saline 0.3 mL/kg) intravenously and a 4 to 5 mm longitudinal aortotomy created in the infra renal aorta before resuscitation commenced with 0.9% saline to one of two target systolic arterial blood pressures (SBPs): 110 mm Hg (normotensive) or 80 mm Hg (hypotensive). Group sizes were as follows: placebo/normotensive (6), placebo/hypotensive (7), rFVIIa/normotensive (7), and rFVIIa/hypotensive (7). Survival was monitored for a maximum of 6 hours after the onset of resuscitation.

RESULTS

rFVIIa was associated with a significantly prolonged survival time in animals managed hypotensively (214 [79-349] vs. 35 [19-52] minutes mean [95% confidence interval] rFVIIa vs. placebo, p = 0.03 Peto log rank test). There was no significant difference in survival time between those given rFVIIa and placebo in groups managed normotensively (128 [6-249] vs. 40 [15-66] minutes respectively, p = 0.27). Both rFVIIa and hypotensive management were associated with reduced uncontrolled hemorrhage volumes. There was no evidence of inappropriate intravascular thrombi or microthrombi associated with the use of rFVIIa.

CONCLUSIONS

rFVIIa, combined with hypotensive resuscitation, can increase survival time and reduce hemorrhage in a model of arterial hemorrhage. The increase in survival time is clinically relevant for military evacuation of battlefield casualties to surgical care.

Emerging therapies for acute ischemic stroke

Stroke is a major public health problem in the United States and the development of novel therapeutic strategies is an important research priority. Advances in this field are proceeding on several fronts, including the use of next-generation plasminogen activators and glycoprotein IIb/ IIIa inhibitors, refined patient selection with advanced magnetic resonance imaging sequences, endovascular approaches to thrombolysis and thrombectomy, and adjuvant use of ultrasound. There remains no proven therapy for intracerebral hemorrhage, but early results with recombinant activated factor VII look very promising. It is hoped that in the near future, physicians managing patients with acute neurological events will have a robust armamentarium of therapies to bring to bear on both ischemic and hemorrhagic vascular disease.

Health economic review of recombinant activated factor VII for treatment of bleeding episodes in hemophilia patients with inhibitors

Severe hemophilia with inhibitors is a rare disease with substantial clinical, humanistic and economic consequences. This review provides an overview of the role of recombinant activated factor VII (rFVIIa) versus plasma-derived bypassing agents for hemophilia with inhibitors and summarizes the 13 formal economic analyses (6 burden of illness and 7 comparative studies) that have been published in this indication. The findings suggest that the economic impact of rFVIIa has occurred primarily during hospitalization to manage major bleeding episodes and to allow for elective orthopedic surgeries that would not have been attempted prior to rFVIIa. Comparative analyses for on-demand treatment suggest that the total cost of treating a bleeding episode with rFVIIa may be lower than with plasma-based agents due to faster bleeding resolution, higher initial efficacy rates and avoidance of second and third lines of treatment.

[Laboratory monitoring of recombinant factor VIIA effects]

Recombinant activated factor Vll originally proposed to prevent and arrest bleedings in patients with the inhibitory form of hemophilia has been shown to be a universal hemostatic agent that is effective in arresting and preventing a broad spectrum of spontaneous and postoperative hemorrhages. Procedures for monitoring the action of this agent on the hemostatic system have not been studied so far. The paper presents the results of a study of various parameters of the hemostatic system in patients with profuse hemorrhages before and after the use of recombinant activated factor VII. It has been ascertained that monitoring of the pharmacokinetics of the agent can be achieved when the prothrombin test with bovine thromboplastin is carried out.

Recombinant Activated Factor VII Treatment of Retroperitoneal Hematoma in a Patient with Renal Failure Receiving Enoxaparin and Clopidogrel

Enoxaparin is a low-molecular-weight heparin that has pharmacokinetic and therapeutic advantages over unfractionated heparin in certain clinical conditions. However, its administration is not without risk. We describe the case of a 70-year-old woman with numerous medical problems who developed severe retroperitoneal bleeding after receiving several therapeutic doses of subcutaneous enoxaparin that inadvertently were not adjusted for her renal function until day 14 of therapy. She had severe bleeding with hemodynamic instability and required massive transfusions of blood products. Her bleeding could be controlled only by administration of four doses of recombinant activated factor VII (factor VIIa) in addition to embolization of the bleeding sites through angiographic microcoiling. The patient's hemodynamic status improved, and her hemoglobin level stabilized. This case report provides evidence of the clinical effectiveness of factor VIIa use as part of the management of refractory enoxaparin-induced retroperitoneal bleeding. However, further studies are needed to validate the dose-response relationship and further support the clinical utility of factor VIIa in this life-threatening situation.

Recombinant factor VIIa: its background, development and clinical use

PURPOSE OF REVIEW

To examine the development of recombinant FVIIa (rFVIIa); a new concept of inducing hemostasis. It was developed for use in hemophilia patients with inhibitors against FVIII or FIX with the vision to provide these patients with a therapeutical option to be used instead of FVIII or FIX. For the first time it was shown that pharmacological doses of FVIIa induced hemostasis.

RECENT FINDINGS

Hemostasis was achieved by rFVIIa in major surgery (repeated doses) as well as in a home-treatment setting (one single injection) in severe hemophilia patients with inhibitors. A recent study indicates that rFVIIa may be useful as prophylaxis. In heavily bleeding nonhemophilia patients rFVIIa was shown to induce hemostasis. Pharmacological doses of rFVIIa enhance thrombin generation on activated platelets resulting in the formation of tight hemostatic fibrin plugs resistant against premature proteolysis. High doses of rFVIIa seem to be safe probably due to its localized effect.

SUMMARY

Pharmacological doses of rFVIIa induce hemostasis in severe hemophilia and in nonhemophilia patients with profuse, heavy bleeding. rFVIIa enhances thrombin generation on activated platelets, thereby initiating the formation of strong, tight fibrin hemostatic plugs resistant to premature lysis. It also seems to be safe in high doses.

Sequential therapy with activated prothrombin complex concentrates and recombinant FVIIa in patients with severe haemophilia and inhibitors: update of our previous experience

Haemophilia patients with inhibitors can develop bleeding episodes, which are refractory to monotherapy with either recombinant factor VIIa (rFVIIa) or activated prothrombin complex concentrates (APCC). Management of such bleeds is often difficult. We previously reported the safety of using a combination of rFVIIa and APCC given in sequential fashion. In this report, we update our experience with sequential therapy. A retrospective review of medical records was conducted including all reports of sequential therapy defined as receiving both rFVIIa and APCC within 6 h. Data extracted included demographic data, treatment prior to and following hospital admission, clinical data including type and location of bleed, response to therapy, physical examination and laboratory data. In addition, for some patients, thromboelastography was performed to document the effect of sequential therapy on clot formation characteristics. Four patients comprising 35 admissions, 209 hospital days and 115 days of sequential therapy were included in the updated dataset. No patient developed thrombosis or overt disseminated intravascular coagulation (DIC) although elevations in the D-dimer above 5 microg mL(-1) were noted in 42% of the courses that lasted >3 days. Efficacy is suggested by the fact that patients had resolution of their bleeds after a median of 3 days of sequential therapy after failing to respond to a median of 3 days of monotherapy. Thromboelastography demonstrated an additive effect. Sequential therapy is a safe, potentially efficacious approach in the management of refractory bleeding episodes in patients with haemophilia and inhibitors.

Pharmacology and clinical use of recombinant activated factor seven in neurosciences

Recombinant activated factor VII (rFVIIa, NovoSeven, NovoNordisc, Danemark) has been approved for the treatment of patients with hemophilia with inhibitors, further indications, at least in some countries, include the treatment of factor VII deficiency and Glanzmann thrombasthenia refractory to conventional therapy. Apart from these indications, the agent is increasingly used for the treatment of severe and potentially life-threatening bleeding manifestations, irrespective of the underlying hemostatic abnormality. The agent has successfully been used for the treatment of both inherited and acquired coagulopathies as well as thrombocytopathia or thrombocytopenia, however, most information on off-label use derives from case reports and retrospective studies and therefore publication bias can-not be excluded. In this review, we focus on the use of rFVIIa for the treatment of spontaneous and perioperative intracranial hemorrhage as well as trauma patients. We review the current knowledge regarding the physiology of hemostasis, the pharmacology of rFVIIa, and its clinical use in neurosciences. Further studies are urgently needed to define the efficacy and safety of recombinant activated factor VII in patients without hemophilia, factor VII deficiency, or Glanzmann thrombasthenia. At time, its use can be justified in life-threatening bleeding situations refractory to conventional treatment.

The potential role of recombinant activated FVII in the management of critical hemato-oncological bleeding: a systematic review

Recombinant activated factor VII (rFVIIa) is an hemostatic agent that was originally developed for the treatment of hemorrhage in patients with hemophilia and inhibitors. However, in the last few years rFVIIa has been employed with success in a broad spectrum of congenital and acquired bleeding conditions. In this systematic review we present the current knowledge on the use of this drug in patients suffering from hemato-oncological disorders, which are quite commonly complicated by severe hemorrhage. On the whole, data in the literature suggest a potential role for rFVIIa in the management of bleeding unresponsive to standard therapy in patients with hematological malignancies, including those undergoing bone marrow transplant. However, the vast majority of the currently available data are derived from uncontrolled studies including single cases or small series of patients. Thus, further trials with larger numbers of patients are needed to establish the most appropriate doses and timing of rFVIIa and to assess its efficacy and safety in this setting.

Utilization of recombinant activated factor VII in a case of spontaneous massive haemothorax in a patient with Von Recklinghausen's disease

Spontaneous haemothorax is a rare and often lethal complication of neurofibromatosis. Two kinds of vascular involvement are described: 1) stenotic or aneurysmatic modifications of large intrathoracic vessels, mainly treated with endovascular techniques; 2) dysplastic alterations in highly vascularized mesenchymal tumors. We describe a rare case of massive intrathoracic haemorrhage due to an upper mediastinic neurofibroma, successfully controlled with recombinant activated factor VII associated with surgical treatment.

Hémorragie sous-arachnoïdienne par rupture d'anévrisme et déficit en facteur VII, à propos d'un cas

The management of subarachnoid haemorrhage by aneurysm rupture is well codified. Some rare cases can be problematical. We report a case of a patient suffering from factor VII (FVII) deficiency who presented a subarachnoid haemorrhage by sylvian aneurysm rupture. The bleeding risk was prevented by plasmatic factor VII substitution and aneurysm coiling. Anticoagulation in order to prevent from thromboembolic risk after embolisation was started for 36 hours, associated with plasmatic FVII substitution (with an objective of plasmatic FVII rate of 30%). After this stage at high thromboembolic risk, there has been no shift to platelet antiaggregants and FVII substitution was stopped. The outcome at 1 month was propitious without any bleeding nor arterial thrombosis.

Use of Recombinant Factor VIIa During Excision of Vascular Anomalies

BACKGROUND

The surgical excision of vascular anomalies is often accompanied with significant perioperative bleeding. Novel hemostatic agents, including recombinant factor VIIa (rVIIa), have been shown to reduce bleeding in hemophilia and trauma patients along with decreasing blood loss during various surgical procedures. The role of rVIIa during excision of vascular anomalies has not been examined.

METHODS

A retrospective chart review of patients from 2001 to 2003 who received perioperative rVIIa during excision of vascular anomalies at one institution.

RESULTS

Nine patients were identified who received perioperative rVIIa during removal of their vascular anomalies (7 venous malformations, 1 lymphatic-venous malformation, 1 arteriovenous malformation). All patients received at least one dose of rVIIa during the perioperative period (2/9 received 2 doses). An accurate account of hourly blood loss was reported, and could be graphed, in three patients. These patients displayed significant reductions in hourly blood loss after the administration of rVIIa. These cases are detailed in this report. Surgeons reported subjective improvements in operative bleeding, efficiency, and operative time in six of six patients after the administration of rVIIa intraoperatively. Reduced postoperative bleeding was reported in two patients who received rVIIa for persistent drain output.

CONCLUSION

rVIIa may be an effective adjunct in improving the surgical efficiency and outcome of excised vascular anomalies.

Recombinant activated clotting factor VII (rFVIIa) in the treatment of surgical and spontaneous bleeding episodes in hemophilic patients

Inhibitors against replacement clotting factors occur in approximately 30%–40% of patients with hemophilia A and 1.5%–3% of patients with hemophilia B. In this group of patients, bleeding events are best treated with bypassing agents. Recombinant activated factor VII (rFVIIa) has become the first-line agent in treating surgical and non-surgical bleeding in many centres with efficacy at standard 90 μg/kg doses approaching 90%. The greater efficacy is associated with early initiation of treatment, as well as, possibly larger doses of rFVIIa. A higher concentration appears to be essential in initiating an adequate thrombin burst, which results in a stable clot. Higher dosage regimens, home therapy and continuous infusion regimens are continuously evolving as we strive to define optimal dosing strategies in hemophilia patients. rFVIIa has been a remarkably safe agent for hemophiliacs but with high dosages being advocated and older patients being given such doses outside a trial setting, thromboembolic events remain a concern.

rFVIIa--for acute rebleeding of a cerebral cavernous malformation

Recurrent bleeding episodes of cavernomas especially in the brainstem can cause progressive neurological deficits. Therefore brainstem cavernomas are still a therapeutic dilemma and a treatment challenge for the neuro critical care community. We report a 39-year-old woman with spontaneous ataxia diplopia and vomiting, who has been treated for multiple intracerebral cavernomas during the last 10 years. A cerebral computed tomography (cCT) revealed a re-bleeding cavernoma in the left cerebral peduncle with consecutive obstructive hydrocephalus. As a result of the difficult anatomical location, no surgical approach was possible. As an off-label treatment, recombinant activated factor VII (rFVIIa) was administered to prevent possible further bleeding and especially further sequelae. The patient recovered well and no adverse events and especially no further bleeding of the cavernoma were observed. To our knowledge, this is the first report of the safe and successful use of rFVIIa to treat re-bleeding episodes in cavernomas. Further clinical studies are needed to specify the future potential of rFVIIa.

Successful management of intra-abdominal hemorrhage in the presence of severe alcoholic liver disease with activated recombinant factor VII (rFVIIa; NovoSeven): a case report and review of the literature on approved and off-label use of rFVIIa

A 37-year-old male with history of alcohol abuse presented to us with nausea, vomiting, and abdominal pain with ascites. He was diagnosed with alcoholic liver disease with coagulopathy and pancreatitis. During hospitalization, the patient developed intra-abdominal hemorrhage. He was treated with platelets, packed red blood cells and fresh frozen plasma without any improvement. Following this he was treated with activated recombinant factor VII (90 microg/kg), which resulted in normalization of the prothrombin time and the activated partial thromboplastin time and stabilization of hematocrit within a few hours. We review the current literature on the approved and off-label use of activated recombinant factor VII.

Recombinant activated factor VII for hemostatic cover of orthopedic interventions in a girl with thrombocytopenia with absent radii syndrome

Over the past 10 years recombinant activated factor VIIa (rFVIIa) has been successfully used for treatment and prophylaxis of bleeding in patients with platelet defects, including thrombocytopenia and congenital and acquired platelet function abnormalities. Most reported data concern patients with Glanzmann's thrombasthenia and the information available is still limited, especially for surgery. We report on a 15-year-old girl with thrombocytopenia ( approximately 60,000/microl) and platelet dysfunction (bleeding time 30 min, absent platelet aggregation and ATP secretion in response to collagen), related to thrombocytopenia with absent radii syndrome, undergoing two surgical interventions on the upper limbs due to forearm deformities, with prolonged postoperative revisions. In both surgeries rFVIIa was successfully employed as a bolus administration (80 microg/kg every 4 h during the first day, then every 6 h over the following 5 and 3 days, respectively; tranexamic acid was associated from the second day, administered for 2 weeks), avoiding the need for blood products. This report highlights rFVIIa as an attractive, alternative approach to secure hemostasis in patients with platelet defects; on the other hand, the heterogeneity of reported rFVIIa treatment regimens and, in particular, the lack of definite and easily available parameters (or assays) for monitoring rFVIIa efficacy and safety are the main open issues in this setting.

Various Local Hemostatic Agents with Different Modes of Action; an in vivo Comparative Randomized Vascular Surgical Experimental Study

OBJECTIVES

To evaluate the effects of different local hemostatic agents in a new high flow vascular experimental bleeding model.

DESIGN

Bovine thrombin combined with collagen matrix (bTcM), microporous polysaccharide hemospheres (MPH), freeze-dried rFVIIa with and without the combination of MPH were compared to a control group (solely compression) in a randomized fashion (20 animals/group). Primary endpoint was hemostasis, and secondary endpoints were time to hemostasis, blood loss, and blood pressure at hemostasis.

METHODS

The common carotid artery of heparinized rats was ligated proximally and transected. Compression was applied for one minute followed by application of the topical hemostatic agent. Compression was maintained for another two minutes followed by re-evaluation of hemostasis: if bleeding continued additional compression was applied and thereafter bleeding was checked every minute until hemostasis.

RESULTS

All animals in the bTcM group obtained hemostasis compared to 20% in the control group (p<0.0001). The combination of MPH and rFVIIa (70% hemostasis) also showed a significant hemostatic capacity compared to control group (p<0.001). None of the other active treatment groups differed compared to control group. Animals treated with bTcM had a significantly shorter time to hemostasis compared to animals in the other active treatment groups. No significant difference in blood loss and blood pressure at hemostasis was detected.

CONCLUSIONS

The most effective hemostatic agent was bTcM, followed by the combination of rFVIIa and MPH, while neither MPH nor rFVIIa alone displayed any hemostatic capacity compared to compression only.

Recombinant Activated Factor VII in Cardiac Surgery: A Systematic Review

Postoperative hemorrhage is a common complication in cardiac surgery, and it is associated with a considerable increase in morbidity, mortality, and cost. Recombinant activated factor VII (rFVIIa) is an emerging hemostatic agent, increasingly used in cardiac surgery. This article systematically reviews the evidence regarding the efficacy, safety, and cost of rFVIIa in this setting. Although definitive evidence from randomized controlled trials is lacking, the use of rFVIIa in patients experiencing refractory postoperative hemorrhage seems promising and relatively safe. However further research is required to definitively establish its clinical utility in the postoperative cardiac patient.

Recombinant activated factor VII efficacy and safety in a model of bleeding and thrombosis in hypothermic rabbits: a blind study

BACKGROUND

Recombinant activated factor VII (rFVIIa) is increasingly used to secure hemostasis in hemorrhagic situations in trauma and surgical patients. Hypothermia is often observed in these clinical settings.

OBJECTIVE

To study the efficacy and safety of rFVIIa in hypothermia in a rabbit model of bleeding and thrombosis.

METHODS

Sixty-nine rabbits were anesthetized, ventilated and monitored for blood pressure, temperature and carotid flow. The Folts model was used: a stenosis (75%) and an injury were carried out on the carotid artery, inducing thrombosis. Blood flow decreased as thrombus size increased until the pressure gradient was such that the thrombus was released and local arterial blood flow was suddenly restored. This is known as a cyclic flow reduction (CFR). After counting baseline CFRs during a 20-min period (P1), rabbits were randomized blindly to one of four groups: normothermic (NT) placebo or rFVIIa (150 microg kg(-1)), hypothermic (HT) (34 degrees C) placebo or rFVIIa. Then CFRs were recorded over a second period (P2). At the end of the experiment, a hepato-splenic section was performed and the amount of blood loss was recorded. After each period, the following were measured: ear immersion bleeding time (BT), hemoglobin, platelet count, prothrombin time (PT), activated partial thromboplastin time (aPTT) and fibrinogen.

RESULTS

Hypothermia increased BT and blood loss. These effects were reversed by rFVIIa. In NT rabbits, rFVIIa shortened BT but did not reduce blood loss. rFVIIa-treated rabbits bled similarly regardless of temperature. The incidence of CFRs was higher in treated than placebo animals regardless of temperature. rFVIIa decreased PT and aPTT without modifying platelet count or fibrinogen level.

CONCLUSION

Hemostatic efficacy of rFVIIa was maintained in hypothermia. However, the number of CFRs was higher in the rFVIIa-treated group than in the placebo groups, whether for NT or HT rabbits.