Hemostatic agents

Principles of minimize bleeding and the transfusion of blood and its components in operated patients - surgical aspects

One of the target of perioperative tratment in surgery is decreasing intraoperative bleeding, which increases the number of perioperative procedures, mortality and treatment costs, and also causes the risk of transfusion of blood and its components. Trying to minimize the blood loss(mainly during the operation) as well as the need to transfuse blood and its components (broadly understood perioperative period) should be standard treatment for a patient undergoing a procedure. In the case of this method, the following steps should be taken: 1) in the preoperative period: identyfication of risk groups as quickly as possible, detecting and treating anemia, applying prehabilitation, modyfying anticoagulant treatment, considering donating one's own blood in some patients and in selected cases erythropoietin preparations; 2) in the perioperative period: aim for normothermia, normovolemia and normoglycemia, use of surgical methods that reduce bleeding, such as minimally invasive surgery, high-energy coagulation, local hemostatics, prevention of surgical site infection, proper transfusion of blood and its components if it occurs; 3) in the postoperative period: monitor the condition of patients, primarily for the detection of bleeding, rapid reoperation if required, suplementation (oral administration preferred) nutrition with microelements (iron) and vitamins, updating its general condition. All these activities, comprehensively and in surgical cooperation with the anesthesiologist, should reduce the blood loss and transfusion of blood and its components.

Tissue factor-loaded collagen/alginate hydrogel beads as a hemostatic agent

Uncontrolled hemorrhage accounts for a significant proportion of annual mortality worldwide. The development of bioinspired hemostatic composites can effectively reduce hemorrhage and related deaths. This work aims to develop an efficient hemostatic agent by incorporating tissue factor (TF) integrated liposomes and collagen, which are capable of augmenting different inherent hemostatic mechanisms, into hemostasis-stimulating alginate matrix. The composite of TF, collagen and alginate (TCA) was made into hydrogel beads with a diameter range of 2.5-3.5 mm, followed by electron microscopy, infrared spectroscopy, rheological, and swelling characterization to confirm its composition and hydrogel nature. When the TCA beads were introduced into simulated body fluid, a controlled release of the loaded TF-liposomes was observed, which also accelerated with the increase of temperature, obtaining intact free proteoliposomes as demonstrated by fluorescence measurement. It is further seen that TCA beads induced the coagulation of whole rabbit blood in about 4.5 min, as compared to ~14.4 min for the control with only recalcified blood. The lipidated TF, collagen and alginate in TCA beads showed a positive synergistic effect on coagulation, while among them a decreasing procoagulant effect was observed. Finally, we demonstrated by a live/dead cell assay that TCA particles had undetectable cytotoxicity. Thus, the TCA hydrogel macrobeads may offer a potential platform for the development of potent hemostatic agents.

Perioperative management of the bleeding patient

Perioperative bleeding remains a major complication during and after surgery, resulting in increased morbidity and mortality. The principal causes of non-vascular sources of haemostatic perioperative bleeding are a preexisting undetected bleeding disorder, the nature of the operation itself, or acquired coagulation abnormalities secondary to haemorrhage, haemodilution, or haemostatic factor consumption. In the bleeding patient, standard therapeutic approaches include allogeneic blood product administration, concomitant pharmacologic agents, and increasing application of purified and recombinant haemostatic factors. Multiple haemostatic changes occur perioperatively after trauma and complex surgical procedures including cardiac surgery and liver transplantation. Novel strategies for both prophylaxis and therapy of perioperative bleeding include tranexamic acid, desmopressin, fibrinogen and prothrombin complex concentrates. Point-of-care patient testing using thromboelastography, rotational thromboelastometry, and platelet function assays has allowed for more detailed assessment of specific targeted therapy for haemostasis. Strategic multimodal management is needed to improve management, reduce allogeneic blood product administration, and minimize associated risks related to transfusion.

Effect of fibrin vs cellulose based haemostatic agents with traditional haemostatic procedures in thyroid surgery

Objective:

To compare the efficacy of fibrin-based hemostat and cellulose-based hemostat with traditional procedures in patients undergoing thyroid surgery.

Methods:

Between January 2012 and December 2016, 255 patients were scheduled to undergo total thyroidectomy at Surgical Clinic Nis. The patients were randomized to: Group-I use of classic surgical procedures to achieve hemostasis, Group-II use Surgicel and Group-III use Beriplas

Results:

A statistically significant reduction of surgical time was found for Group-I compared with Group-II and III (p≤0.01 for both groups). Statistically significant reduction of intraoperative blood loss was found for Group-I compared with Group-II from 102.3mL vs. 86.1mL (p≤0.01) as well as compared to Group-III (mean 77.4mL, p≤0.01). Removal of the wound drain occurred sooner in the Group-II and III compared with Group-I (mean 37.1h vs. 40.1h, p≤0.05; mean 31.2h vs. 40.1h, p≤0.01). There were no significant differences in terms of postoperative morbidity among the groups.

Conclusions:

Fibrin based haemostat seems to be an effective hemostatic agent for patients undergoing thyroid surgery. We suggest that, where appropriate, this fibrin-based haemostat should be used as a first line hemostatic agent in thyroidectomy in combination with conventional surgical means of hemostasis.

Biomaterials and Advanced Technologies for Hemostatic Management of Bleeding

Bleeding complications arising from trauma, surgery, and as congenital, disease-associated, or drug-induced blood disorders can cause significant morbidities and mortalities in civilian and military populations. Therefore, stoppage of bleeding (hemostasis) is of paramount clinical significance in prophylactic, surgical, and emergency scenarios. For externally accessible injuries, a variety of natural and synthetic biomaterials have undergone robust research, leading to hemostatic technologies including glues, bandages, tamponades, tourniquets, dressings, and procoagulant powders. In contrast, treatment of internal noncompressible hemorrhage still heavily depends on transfusion of whole blood or blood's hemostatic components (platelets, fibrinogen, and coagulation factors). Transfusion of platelets poses significant challenges of limited availability, high cost, contamination risks, short shelf-life, low portability, performance variability, and immunological side effects, while use of fibrinogen or coagulation factors provides only partial mechanisms for hemostasis. With such considerations, significant interdisciplinary research endeavors have been focused on developing materials and technologies that can be manufactured conveniently, sterilized to minimize contamination and enhance shelf-life, and administered intravenously to mimic, leverage, and amplify physiological hemostatic mechanisms. Here, a comprehensive review regarding the various topical, intracavitary, and intravenous hemostatic technologies in terms of materials, mechanisms, and state-of-art is provided, and challenges and opportunities to help advancement of the field are discussed.

Retrospective Study of 122 Dogs That Were Treated with the Antifibrinolytic Drug Aminocaproic Acid: 2010-2012

Antifibrinolytic drugs are used to promote hemostasis and decrease the need for red blood cell transfusion. Medical records of 122 dogs that were prescribed either oral or intravenous aminocaproic acid between 2010 and 2012 were evaluated retrospectively. Of the 122 dogs, three experienced possible drug-related adverse effects. No significant differences were identified between dogs that experienced adverse effects and those that did not and the possible adverse effects noted were all minor. All dogs that received packed red blood cell transfusions were evaluated for correlations between baseline packed cell volume or dose of red blood cells and aminocaproic acid dose and no correlation was identified. Dogs that received aminocaproic acid as a treatment for active bleeding were divided by cause of hemorrhage into the following groups: neoplastic, non-neoplastic, and unknown. No significant differences in aminocaproic acid dose or the percentage of patients requiring a blood transfusion were identified between groups.

Blood utilization: fostering an effective hospital transfusion culture

An effective hospital transfusion culture should encourage clinicians to consider the possibility of transfusion in their patients well before the need actually arises, and to plan ahead in an attempt to use blood products most efficiently. Strategies for improved blood utilization include timely and adequate preoperative assessment of risk, optimization of baseline hemoglobin, anticipation of potential transfusion problems, intraoperative techniques to minimize blood loss, blood conservation technologies, transfusion guidelines and targeted therapy, point of care testing, and massive transfusion protocols. Attention to these elements promotes a safe and cost-effective transfusion culture.

Reducing Heavy Menstrual Bleeding: Safety and Efficacy of Tranexamic Acid

Menorrhagia or Heavy Menstrual Bleeding (HMB) remains a public health challenge among women in the reproductive age group. Anti-fibrinolytics such as tranexamic acid and epsilon aminocaproic acid, play an important role in the medical management of HMB, as HMB is associated with an increase in local fibrinolysis. Lysteda is a novel oral formulation of tranexamic acid which has recently been approved by the US FDA for treatment of HMB. Efficacy of tranexamic acid in the general gynecologic population as well as in women with bleeding disorders is discussed in this review. Safety and adverse effect profile is also addressed for both these populations.

Anesthetic concerns for patients with coagulopathy

PURPOSE OF REVIEW

Patients often receive preoperative therapies that interfere with hemostasis, and can present for surgery with underlying hemostatic disorders because of pre-existing preoperative anticoagulation or antiplatelet therapy. Perioperative bleeding can occur following surgery due to multiple causes; however, the addition of pharmacologic agents creates an acquired defect that complicates the surgical injury and may result in increased blood loss. An understanding of the potential impact of anticoagulation therapies on hemostasis is critical in managing these patients. Further, newer agents are evolving in clinical practice that clinicians should be aware of.

RECENT FINDINGS

The anticoagulants and antiplatelet agents that patients are receiving preoperatively apart from unfractionated heparin include low-molecular-weight heparins (LMWHs); a pentasaccharide (fondaparinux); oral anticoagulants: vitamin K antagonists (warfarin), new oral Xa inhibitors (rivaroxaban, apixiban), or the oral direct thrombin inhibitor (DTI) dabigatran; platelet inhibitors: thienopyridines (clopidogrel, ticlopidine, prasugrel) or IIb/IIIa receptor antagonists (tirofiban, abciximab, eptifibatide); or DTIs (r-hirudin, bivalirudin, argatroban).

SUMMARY

There are multiple pharmacologic therapies that surgical patients may be exposed to preoperatively, although there are currently few available methods to antagonize their effects. Often therapeutic prohemostatic pharmacologic approaches are used to treat or prevent bleeding, in addition to transfusional therapies.

Topical haemostatic agents

BACKGROUND

A variety of local haemostatic agents is now available to stop troublesome bleeding. These agents are indicated for use during surgical interventions where conventional methods of haemostasis are not applicable because of the site of surgery or the degree of bleeding.

METHOD

A literature search using the PubMed and ISI Web of Knowledge databases identified relevant studies on topical haemostatic agents. Manufacturers' recommendations were also sought through commercial websites.

RESULTS AND CONCLUSION

A significant body of evidence now exists to support the use of topical haemostatic agents in a wide variety of clinical situations. The advantages and disadvantages of many of these agents are highlighted.

A benefit-risk review of systemic haemostatic agents: part 1: in major surgery

Systemic haemostatic agents play an important role in the management of blood loss during major surgery where significant blood loss is likely and their use has increased in recent times as a consequence of demand for blood products outstripping supply and the risks associated with transfusions. Their main application is as prophylaxis to reduce bleeding in major surgery, including cardiac and orthopaedic surgery and orthotopic liver transplantation. Aprotinin has been the predominant agent used in this setting; of the other antifibrinolytic agents that have been studied, tranexamic acid is the most effective and epsilon-aminocaproic acid may also have a role. Eptacog alfa (recombinant factor VIIa) has also shown promise. Tranexamic acid, epsilon-aminocaproic acid and eptacog alfa are generally well tolerated; however, when considering the methods to reduce or prevent blood loss intra- and postoperatively, the benefits of these agents need to be weighed against the risk of adverse events. Recently, concerns have been raised about the safety of aprotinin after an association between increased renal dysfunction and mortality was shown in retrospective observational studies and an increase in all-cause mortality with aprotinin relative to tranexamic acid or epsilon-aminocaproic acid was seen after a pre-planned periodic analysis of the large BART (Blood conservation using Antifibrinolytics in a Randomized Trial) study. The latter finding resulted in the trial being halted, and aprotinin has subsequently been withdrawn from the market pending detailed analysis of efficacy and safety results from the study. Part 1 of this benefit-risk review examines the efficacy and adverse effect profiles of systemic haemostatic agents commonly used in surgery, and provides individual benefit-risk profiles that may assist clinicians in selecting appropriate pharmacological therapy in this setting.

Key concepts in the management of difficult hemorrhagic cases

Goals of hemorrhage management involve promoting coagulation and reducing fibrinolysis to enhance clot formation and stability, and minimizing hemorrhagic expansion to reduce the likelihood of adverse outcomes. The optimal hemostatic regimen to obtain these goals will differ according to the clinical scenario. Two hypothetical cases of patients with hemorrhage are presented that are typical of those encountered by clinical pharmacists who practice in centers that treat trauma or surgical patients or patients in need of emergency or critical care because of serious bleeding. To maximize therapy, the clinician must be aware of how best to clinically apply hemostatic agents, their comparative benefits and disadvantages, and the optimal methods for monitoring their effectiveness and toxicities.

Blood management

CONTEXT

We provide an overview of the principles of blood management: the appropriate use of blood and blood components, with a goal of minimizing their use.

OBJECTIVE

To review the strategies that exploit combinations of surgical and medical techniques, technologic devices, and pharmaceuticals, along with an interdisciplinary team approach that combines specialists who are expert at minimizing allogeneic blood transfusion.

DATA SOURCES

A search on Medline and PubMed for the terms English and humans used in articles published within the last 20 years.

CONCLUSIONS

Blood management is most successful when multidisciplinary, proactive programs are in place so that these strategies can be individualized to specific patients.

The Balance of Thrombosis and Hemorrhage in Surgery

Postoperative hemorrhage and thrombosis is a significant problem during the perioperative period. Understanding the complex and dynamic interplay of factors, proteins, and enzymes during coagulation is imperative to maintain balance between hemostasis and thrombosis. To improve patient outcome, each patient should be risk stratified for bleeding or thrombosis during the preoperative examination. Additional research focused on improvement in screening tools, monitoring, and therapeutic regimens for surgical patients with a coagulopathy are warranted.

Blood loss minimization and blood salvage techniques for complex spinal surgery

Several techniques to limit blood loss and salvage lost blood are available to surgeons, physicians, and personnel who treat complex spinal disorders. These techniques include red blood cell augmentation, intraoperative antifibrinolytic administration, use of topical hemostatic agents, and intraoperative blood salvage and postoperative blood salvage. A substantial amount of research has been directed toward reducing perioperative blood loss in spinal surgery. More efforts need to be directed toward effective perioperative blood management in complex spinal surgery.

Aprotinin in the management of coagulopathy associated with amniotic fluid embolus

Amniotic fluid embolus, also known as anaphylactoid syndrome of pregnancy is a rare complication of pregnancy. When it occurs, the maternal mortality rate may be as high as 86%, and in survivors, the morbidity rate may be just as high. Hallmark clinical features include maternal cardiovascular collapse with disseminated intravascular coagulation, and fetal distress. Management centers on strategies to improve oxygenation, support circulation, and correct the coagulopathy. We report the case of a patient who developed amniotic fluid embolus and was effectively managed with aprotinin to control the coagulopathy associated with this devastating complication of pregnancy.

An improved 99mTc-aprotinin kit formulation: quality control analysis of radiotracer stability and cold kit shelf life

(99m)Tc-aprotinin scintigraphy has been demonstrated to be a useful noninvasive imaging technique for amyloid deposits located in extraabdominal regions of patients. The aim of this study was to develop an improved aprotinin cold kit formulation, to validate the kit for long-term stability, as well as to assess the radiotracer stability by novel quality control methods. The aprotinin cold kit formulation of Trasylol, pyrophosphate (PYP)-chelated stannous reductant and an alkaline buffer, was dispensed into nitrogen-filled vials and aliquots frozen at -20 degrees C. After 0, 1, 2, 3 and 6 months of storage, three samples were reconstituted with 750-850 MBq of (99m)Tc-pertechnetate, followed by quality control analyses by paper chromatography methods at 25, 85 and 265 min postreconstitution (pr). Cation-exchange cartridge quality control methods were also investigated. The cold kits proved to be stable to long-term storage for up to 6 months, and the radiotracer was stable for at least 4 h pr. (99m)Tc-aprotinin was formed at greater than 95% efficiency at all time points tested with (99m)TcO2 present as the major impurity (1-4%) and (99m)Tc-pertechnetate and (99m)Tc-PYP present in trace amounts. An alternative, rapid, safe and reliable method was found in Oasis MCX-BSA-treated cartridges using saline as the eluting solution to assay for (99m)Tc-aprotinin.