Recombinant activated factor VII and the anaesthetist

The Effects of Acidosis and Hypothermia on Blood Transfusion Requirements following Factor VII Administration

While there is laboratory evidence that the activity of recombinant activated factor VII (rFVIIa) is reduced by the presence of acidosis and hypothermia, there is limited clinical data to support this observation. Recombinant FVIIa may be used as rescue therapy in surgical patients who have bleeding that is refractory to conventional therapy. However, these patients are also frequently acidotic and hypothermic at the time the drug is administered. In this retrospective study, the records of 38 adult surgical patients who received rFVIIa intraoperatively or within six hours postoperatively were reviewed. The requirements for red cell transfusion in the two hours following the administration of rFVIIa and the need for repeated doses of rFVIIa were recorded. The relationship between red cell transfusion and pH and temperature of the patient at the time of rFVIIa administration was assessed by multiple regression analysis.

The major finding was an inverse relationship between the degree of acidosis at the time of rFVIIa administration and the requirement for either subsequent blood transfusion or repeat dosing of rFVIIa (P=0.003 and P <0.001 respectively). For patients with apH <7.2 vs. pH >7.2, the odds ratio for receiving two or more packs of red blood cells within two hours of rFVIIa administration was 15:1. This effect was not observed for hypothermia.

The implication of this study is that rFVIIa may be less effective when administered to severely acidotic patients. Further studies are required to examine whether this is related to the acidosis directly, or is secondary to other intraoperative variables affecting acidosis. The clinical utility of rFVIIa in acidotic patients also requires further investigation.

Thrombogenic Side-Effects of Recombinant Factor VIIa after use in Coronary Artery Bypass Surgery

Recombinant activated factor VII (rFVIIa) has been used ‘off licence’ to successfully treat bleeding and reduce transfusion requirements in complex cardiac surgery. However, concerns over thrombogenic side-effects have limited but not excluded its use in patients undergoing coronary artery bypass surgery (CABG).

We present two cases of CABG (one ‘on pump’ and one ‘off pump’) which were complicated by intraoperative aortic dissection and severe bleeding. In both cases the bleeding was successfully treated with rFVIIa. However the first case suffered from severe postoperative arrhythmias, myocardial infarction, cardiac arrest and worsening left ventricular dysfunction, suggesting graft patency may have been impaired, whereas the second case remained symptom-free suggesting graft patency was unaffected by the use of rFVIIa. If rFVIIa is needed to treat bleeding during CABG surgery, it may be more appropriate to administer smaller, repeated doses to minimize the risk of thrombosis and early graft failure.

Comparison of low- and high-dose recombinant activated factor VII for postcardiac surgical bleeding

Aim of the Study:

A retrospective observational study to compare safety and efficacy of high and low doses of recombinant activated factor VIIa (rFVIIa) in severe postcardiac surgical bleeding.

Patients and Methods:

From 2004 to 2014, all patients who received rFVIIa for bleeding after cardiac surgery were included and arranged in two groups; Group 1: Low dose (40–50 mcg/kg) (n = 98) and Group 2: High dose (90–120 mcg/kg) (n = 156).

Results:

There was no significant difference in demographic and surgical characteristics of both groups on admission to Cardiac Surgical Intensive Care Unit (CSICU). There was no significant difference between the two groups regarding the reduction in chest tube bleeding in the first 6 h or the transfusion requirement in the 24 h after admission to CSICU. A total of 15 patients (5.9%) had thromboembolic adverse events. (Seven (7.1%) patients in Group 1 compared to 8 (5.1%) patients in Group 2, P = 0.58). There were no significant differences in all-cause mortality at 30 days (2% in Group 1 vs. 3.2% in Group 2, P = 0.6) and at hospital discharge between the two study groups (6.1% in Group 1 vs. 8.3% in Group 2, P = 0.5), respectively. There was no significant difference between the two groups regarding the need for re-exploration, days on mechanical ventilation, CSICU, or hospital stay.

Conclusion:

In this report, Low-dose rFVIIa showed equivalent efficacy and safety to high-dose rFVIIa. Further prospective randomized studies are needed to confirm these findings.

Combination use of platelets and recombinant activated factor VII for increased hemostasis during acute type a dissection operations

Background

Refractory blood loss is a common problem in surgeries for acute type A aortic dissections. Significant evidence has supported the benefit of using recombinant activated factor VII (rFVIIa) to control of intractable bleeding in patients after cardiac surgery. In this prospective clinical study, we present a novel method to achieve intraoperative hemostasis by using a combination of platelets and rFVIIa during operations for acute type A aortic dissections.

Methods

Between May 2009 and August 2012, 71 patients with acute type A dissections who underwent emergency surgery were prospectively included and allocated to one of the following two intervention groups for hemostasis: 3 units platelets combined with 2.4 mg rFVIIa (n = 25), and conventional methods (n = 46).

Results

The patients who received the combination of platelets and rFVIIa required fewer transfusions of red blood cells (6.2 ± 3.1 units vs 9.8 ± 2.8 units; p < 0.05), fresh frozen plasma (736.9 ± 178.3 ml vs 1264.3 ± 245.2 ml, p < 0.05), platelet concentrates (3 units vs 5.0 ± 1.8 units, p < 0.001), and cryoprecipitate (2.8 ± 0.9 units vs 8.2 ± 2.3 units, p < 0.05). These patients also required less time for sternal closure (76.9 ± 17.2 min vs 102.3 ± 10.7 min, p < 0.05) compared with the conventional therapy patients. There was no statistically significant difference in the incidence of serious adverse events between these two groups.

Conclusions

Using a combination of platelets and rFVIIa is an effective strategy for achieving hemostasis during acute type A dissection surgery. This hemostatic strategy does not appear to be associated with an increase in postoperative adverse events.

Electronic supplementary material

The online version of this article (doi:10.1186/s13019-014-0156-y) contains supplementary material, which is available to authorized users.

Dissecting the contribution of thrombin exosite I in the recognition of thrombin binding aptamer

Thrombin plays a pivotal role in the coagulation cascade; therefore, it represents a primary target in the treatment of several blood diseases. The 15-mer DNA oligonucleotide 5'-GGTTGGTGTGGTTGG-3', known as thrombin binding aptamer (TBA), is a highly potent inhibitor of the enzyme. TBA folds as an antiparallel chair-like G-quadruplex structure, with two G-tetrads surrounded by two TT loops on one side and a TGT loop on the opposite side. Previous crystallographic studies have shown that TBA binds thrombin exosite I by its TT loops, T3T4 and T12T13. In order to get a better understanding of the thrombin-TBA interaction, we have undertaken a crystallographic characterization of the complexes between thrombin and two TBA mutants, TBAΔT3 and TBAΔT12, which lack the nucleobase of T3 and T12, respectively. The structural details of the two complexes show that exosite I is actually split into two regions, which contribute differently to TBA recognition. These results provide the basis for a more rational design of new aptamers with improved therapeutic action.

Intraoperative use of low-dose recombinant activated factor VII during thoracic aortic operations

BACKGROUND

Numerous studies have supported the effectiveness of recombinant activated factor VII (rFVIIa) for the control of bleeding after cardiac procedures; however safety concerns persist. Here we report the novel use of intraoperative low-dose rFVIIa in thoracic aortic operations, a strategy intended to improve safety by minimizing rFVIIa exposure.

METHODS

Between July 2005 and December 2010, 425 consecutive patients at a single referral center underwent thoracic aortic operations with cardiopulmonary bypass (CPB); 77 of these patients received intraoperative low-dose rFVIIa (≤60 μg/kg) for severe coagulopathy after CPB. Propensity matching produced a cohort of 88 patients (44 received intraoperative low-dose rFVIIa and 44 controls) for comparison.

RESULTS

Matched patients receiving intraoperative low-dose rFVIIa got an initial median dose of 32 μg/kg (interquartile range [IQR], 16-43 μg/kg) rFVIIa given 51 minutes (42-67 minutes) after separation from CPB. Patients receiving intraoperative low-dose rFVIIa demonstrated improved postoperative coagulation measurements (partial thromboplastin time 28.6 versus 31.5 seconds; p=0.05; international normalized ratio, 0.8 versus 1.2; p<0.0001) and received 50% fewer postoperative blood product transfusions (2.5 versus 5.0 units; p=0.05) compared with control patients. No patient receiving intraoperative low-dose rFVIIa required postoperative rFVIIa administration or reexploration for bleeding. Rates of stroke, thromboembolism, myocardial infarction, and other adverse events were equivalent between groups.

CONCLUSIONS

Intraoperative low-dose rFVIIa led to improved postoperative hemostasis with no apparent increase in adverse events. Intraoperative rFVIIa administration in appropriately selected patients may correct coagulopathy early in the course of refractory blood loss and lead to improved safety through the use of smaller rFVIIa doses. Appropriately powered randomized studies are necessary to confirm the safety and efficacy of this approach.

Recombinant activated factor VII as treatment for uncontrolled mucosal haemorrhage

We report the use of a haemostatic drug (recombinant activated factor VII (rFVIIa)) in a patient who presented a slow but constant bleed in oesophageal mucosa (which required frequent red blood cell transfusion) due to ingestion of caustic products. The administration of rFVIIa ceased bleeding and allowed mucosal cicatrisation and patient haemodynamic stabilisation and clinical recovery.

Recombinant factor VIIa and the patient with neurologic bleeding: separating fact from fiction

Notwithstanding its limited Food and Drug Administration-approved indications, rFVIIa has rapidly gained widespread use for the treatment of a variety of hemorrhagic conditions, including intracranial bleeding from spontaneous, traumatic, surgical, and coagulopathic causes. Although it appears that the drug only minimally increases the risk of thromboembolic events, its efficacy remains in question. The idea of finding a universal cure for hemorrhage in a medication bottle remains highly appealing, but enthusiasm for the concept is no replacement for evidence. Neuroscience nurses, who are the interface between patients and rFVIIa, need to balance hope and hype until the facts are all in.

Perioperative Coagulopathy, Bleeding, and Hemostasis During Cardiac Surgery

Cardiac surgery patients use 10%-25% of the blood products transfused annually in the United States. The transfusion of red blood cells or blood products has been the subject of intense scrutiny over the past 10 years. Bleeding after cardiac surgery can be surgical or nonsurgical and lead to hemodynamic compromise and surgical reexploration. Because hemorrhage and blood product transfusions are associated with multiple negative outcomes, including increased mortality, it is prudent to understand the mechanisms responsible for nonsurgical bleeding. This review focuses on the physiology of the normal coagulation and fibrinolysis, risk factors associated with patients presenting for cardiac surgery, impairments of normal hemostasis associated with cardiac surgery and cardiopulmonary bypass (CPB), and potential interventions to reduce perioperative blood loss and blood transfusion.

Safety of rFVIIa in hemodynamically unstable polytrauma patients with traumatic brain injury: post hoc analysis of 30 patients from a prospective, randomized, placebo-controlled, double-blind clinical trial

BACKGROUND

Trauma is a leading cause of mortality and morbidity, with traumatic brain injury (TBI) and uncontrolled hemorrhage responsible for the majority of these deaths. Recombinant activated factor VIIa (rFVIIa) is being investigated as an adjunctive hemostatic treatment for bleeding refractory to conventional replacement therapy in trauma patients. TBI is a common component of polytrauma injuries. However, the combination of TBI with polytrauma injuries is associated with specific risk factors and treatment modalities somewhat different from those of polytrauma without TBI. Although rFVIIa treatment may offer added potential benefit for patients with combined TBI and polytrauma, its safety in this population has not yet been assessed. We conducted a post hoc sub analysis of patients with TBI and severe blunt polytrauma enrolled into a prospective, international, double-blind, randomized, placebo-controlled study.

METHODS

A post hoc analysis of study data was performed for 143 patients with severe blunt trauma enrolled in a prospective, randomized, placebo-controlled study, evaluating the safety and efficacy of intravenous rFVIIa (200 + 100 + 100 microg/kg) or placebo, to identify patients with a computed tomography (CT) diagnosis of TBI. The incidences of ventilator-free days, intensive care unit-free days, and thromboembolic, serious, and adverse events within the 30-day study period were assessed in this cohort.

RESULTS

Thirty polytrauma patients (placebo, n = 13; rFVIIa, n = 17) were identified as having TBI on CT. No significant differences in rates of mortality (placebo, n = 6, 46%, 90% confidence interval (CI): 22% to 71%; rFVIIa, n = 5, 29%, 90% CI: 12% to 56%; P = 0.19), in median numbers of intensive care unit-free days (placebo = 0, rFVIIa = 3; P = 0.26) or ventilator-free days (placebo = 0, rFVIIa = 10; P = 0.19), or in rates of thromboembolic adverse events (placebo, 15%, 90% CI: 3% to 51%; rFVIIa, 0%, 90% CI: 0% to 53%; P = 0.18) or serious adverse events (placebo, 92%, 90% CI: 68% to 98%; rFVIIa, 82%, 90% CI: 60% to 92%; P = 0.61) were observed between treatment groups.

CONCLUSION

The use of a total dose of 400 (200 + 100 + 100) microg/kg rFVIIa in this group of hemodynamically unstable polytrauma patients with TBI was not associated with an increased risk of mortality or with thromboembolic or adverse events.

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.

Case report: management of life-threatening oropharyngeal bleeding with recombinant factor VIIa

PURPOSE

To report the use of recombinant factor VIIa (rFVIIa) for management of profuse oropharyngeal bleeding in a cirrhotic patient that nearly resulted in a 'cannot intubate, cannot ventilate' scenario.

CLINICAL FEATURES

A 42-yr-old woman with end-stage liver disease presented for orthotopic liver transplantation. She was dialysis dependent and had marked coagulopathy [international normalized ratio (INR) = 3.1], without evidence of active bleeding. Following uneventful induction of anesthesia, routine airway manipulation for tracheal intubation caused profuse upper airway bleeding making visualization of her airway by direct laryngoscopy impossible. Moreover, several further attempts at tracheal intubation along with the bleeding made manual ventilation progressively more difficult, nearly resulting in a 'cannot intubate, cannot ventilate' scenario. In an attempt to control the bleeding, rFVIIa 4.8 mg iv was administered. Within five minutes, her INR had decreased to 1.1, bleeding was markedly reduced, the vocal cords were successfully visualized using an anterior commissure laryngoscope, and intubation of the trachea was achieved with the use of a gum-elastic bougie. Postintubation examination of the airway showed several abrasions along the right oropharyngeal wall with minimal bleeding. The remainder of surgery and postoperative airway management were uneventful.

CONCLUSIONS

This report demonstrates that in the relatively uncommon setting of upper airway hemorrhage in a patient with pre-existing coagulopathy, rFVIIa can be effective in gaining rapid control of bleeding to facilitate visualization of the vocal cords and securing of the airway.