Lessons from the aprotinin saga: current perspective on antifibrinolytic therapy in cardiac surgery

Tranexamic acid in cardiac surgery: Are low doses enough?

OBJECTIVES

Tranexamic acid is used to prevent hyperfibrinolysis and reduce postoperative bleeding and blood transfusions in on-pump cardiac surgery. We evaluate the efficacy of low or high dose tranexamic acid in a prospective cohort study conducted in Valencia.

MATERIALS AND METHODS

A total of 427 patients were recruited between January 2019 and January 2020, 207 in the Hospital General Universitario (low dose [LD]) and 220 in the Hospital Universitario y Politécnico La Fe (high dose [HD] and intermediate dose [ID]). We recorded the presence of hyperfibrinolysis on rotational thromboelastometry, intra- and postoperative administration of blood products, chest tube output within the first 12 h, and incidence of convulsions. Univariate and multivariate comparisons were performed. Univariate analysis of all categories was performed after propensity score matching between LD and HD and between LD and ID.

RESULTS

There were no statistically significant differences in: appearance of hyperfibrinolysis, administration of blood products, postoperative chest tube output within the first 12 h, or occurrence of convulsions. Group LD received less fibrinogen than group HD (P = .014) and ID (P = .040) but more fresh frozen plasma than group ID (P = .0002).

CONCLUSIONS

Administration of low-dose tranexamic acid is as effective as higher doses in hyperfibrinolysis prophylaxis and the prevention of postoperative bleeding in cardiac surgery.

Tranexamic acid in cardiac surgery: Are low doses enough?

OBJECTIVES

Tranexamic acid is used to prevent hyperfibrinolysis and reduce postoperative bleeding and blood transfusions in on-pump cardiac surgery. We evaluate the efficacy of low or high dose tranexamic acid in a prospective cohort study conducted in Valencia.

MATERIALS AND METHODS

A total of 427 patients were recruited between January 2019 and January 2020, 207 in the Hospital General Universitario (low dose [LD]) and 220 in the Hospital Universitario y Politécnico La Fe (high dose [HD] and intermediate dose [ID]). We recorded the presence of hyperfibrinolysis on rotational thromboelastometry, intra- and postoperative administration of blood products, chest tube output within the first 12h, and incidence of convulsions. Univariate and multivariate comparisons were performed. Univariate analysis of all categories was performed after propensity score matching between LD and HD and between LD and ID.

RESULTS

There were no statistically significant differences in: appearance of hyperfibrinolysis, administration of blood products, postoperative chest tube output within the first 12h, or occurrence of convulsions. Group LD received less fibrinogen than group HD (P=.014) and ID (P=.040) but more fresh frozen plasma than group ID (P=.0002).

CONCLUSIONS

Administration of low-dose tranexamic acid is as effective as higher doses in hyperfibrinolysis prophylaxis and the prevention of postoperative bleeding in cardiac surgery.

Effects of Local Administration of Tranexamic Acid on Reducing Postoperative Blood Loss in Surgeries for Closed, Sanders III-IV Calcaneal Fractures: A Randomized Controlled Study

PURPOSE

To investigate whether local administration of tranexamic acid (TXA) is effective in postoperative blood loss reduction in surgeries for Sanders III-IV calcaneal fractures.

METHODS

Calcaneal fracture patients who were hospitalized in our hospital from August 2014 to April 2018 and underwent open reduction internal fixation (ORIF) via lateral approach with an L-shaped incision were included in the present study. 53 Patients were randomly divided into three groups, groups A (17), B (17) and C (19). Twenty milliliters of 10 mg/ml and 20 mg/ml TXA solution were perfused into the incision of patients in group A and group B, respectively. Twenty milliliters of saline were perfused into the incision of patients in group C as control. The volume of postoperative drainage, postoperative blood test, coagulation test, and wound complications were analyzed to evaluate the effectiveness of local administration of TXA on blood loss reduction.

RESULTS

The amount of drainage at 24 and 48 h after the procedure was 110 ± 170, 30 ± 10 ml and 130 ± 160, 20 ± 17 ml for patients in group A and group B, respectively. The corresponding numbers for patients in group C were 360 ± 320, 20 ± 10 ml. The difference between group A and group C was statistically significant, so was the difference between group B and group C. No statistically significant difference was found between group A and group B. Postoperative blood test results revealed that the levels of hemoglobin and hematocrit were significantly higher in group A and group B when each compared to that of group C. In contrast, no difference was found between group A and group B. No significant difference was found between each experimental group and the control group in terms of platelet counts, prothrombin time (P.T.), activated partial prothrombin time (APTT), and wound complications.

CONCLUSION

Local administration of TXA is effective in the reduction of postoperative blood loss in surgeries for Sanders III-IV types of calcaneal fractures without notably associated side effects.

Administration of Tranexamic Acid in Proximal Humeral Fractures

INTRODUCTION

This study aimed to analyze the efficacy of intravenous administration of tranexamic acid in complex proximal humeral fractures.

MATERIALS AND METHODS

Sixty-seven patients with displaced 3 and 4 part proximal humerus fractures were randomized into the control (n = 33) and TXA (n = 34) groups. Fifteen minutes before the skin incision, 15 mg/kg body weight of 0.9% sodium chloride solution or TXA was injected intravenously. Open reduction and internal fixation was conducted through a deltoid-pectoral approach with fixed angle locked plating (PHILOS) for all the patients. The patients were followed up 2 months after surgery. Total blood loss, blood test results, blood transfusion rate, and wound complications were analyzed between the two groups.

RESULTS

Significant differences were observed in intraoperative blood loss and postoperative blood loss during the first 24 h between the two groups. There were no significant differences in postoperative blood loss during the second 24 h, wound complication rates, blood transfusion rate and adverse side effects. And thromboembolic events related with the application of TXA were not noted in the TXA group.

CONCLUSION

Preoperative administration of tranexamic acid could reduce intraoperative and postoperative blood loss in patients with complex proximal humeral fractures.

LEVEL OF EVIDENCE

II, prospective comparative study.

Compliance of tranexamic acid administration to trauma patients at a level-one trauma centre

Introduction Current practice for the treatment of traumatic hemorrhage includes fluid resuscitation and the administration of blood products. The administration of tranexamic acid (TXA) within 8 hours of injury has been shown to significantly reduce mortality in a large, prospective, randomized controlled trial. As a result, TXA is widely used in trauma centres to manage trauma patients with major bleeding. The primary aim of this study was to assess the compliance of TXA administration at a level-one trauma centre in Hamilton, Ontario, Canada.

METHODS

We conducted a retrospective medical record review of consecutive adult trauma patients received at the Hamilton General Hospital between January 1, 2012 and December 31, 2014. Compliance with TXA administration was based on the inclusion criteria of the CRASH-2 trial.

RESULTS

Five hundred and thirty-four of 2,475 trauma patients met the inclusion criteria for TXA administration. Twenty-one patients who received TXA at peripheral hospital prior to their arrival at the level-one trauma centre were excluded from the analysis, and 18 patients were excluded due to missing data. One hundred and thirty-four patients received TXA, representing a compliance rate of 27%. Mean time from arrival to TXA administration was 47 minutes. Compliance increased for those who required massive transfusion and as the number of criteria for TXA administration increased.

CONCLUSIONS

Compliance with TXA administration to trauma patients with suspected major bleeding was low. Quality improvement strategies aimed at increasing appropriate use of TXA are warranted.

Administration of Tranexamic Acid Reduces Postoperative Blood Loss in Calcaneal Fractures: A Randomized Controlled Trial

The present randomized controlled trial was undertaken to evaluate the effect of tranexamic acid (TXA) on reducing postoperative blood loss in calcaneal fractures. A total of 90 patients with a unilateral closed calcaneal fracture were randomized to the TXA (n = 45) and control (n = 45) groups. The corresponding groups received 15 mg/kg body weight of TXA or placebo (0.9% sodium chloride solution) intravenously before the skin incision was made. Open reduction and internal fixation was performed for all patients and selective bone grafting was performed. The patients were examined 3 months after surgery. The intraoperative and postoperative blood loss, blood test results, and wound complications were compared between the 2 groups. The complications of TXA were also investigated. No statistically significant differences were found in the baseline characteristics between the TXA and control groups. Also, no significant difference was noted in the intraoperative blood loss between the 2 groups. However, in the TXA group, the postoperative blood loss during the first 24 hours was significantly lower than that in the control group (110.0 ± 160.0 mL versus 320.0 ± 360.0 mL; p < .001). The incidence of wound complications was also reduced compared with that in the control group (7.3% versus 23.8%; p = .036). No significant difference was found in the incidence of thromboembolic events or adverse drug reactions between the 2 groups. We concluded that preoperative single-dose TXA can effectively reduce postoperative blood loss and wound complications in patients with calcaneal fractures and that no significant side effects developed compared with the control group.

Novel approaches in management of perioperative coagulopathy

PURPOSE OF REVIEW

The recent advances in hemostatic monitoring, and discussion of the clinical implications of hemostatic therapies based on different blood components and factor concentrates.

RECENT FINDINGS

Implementing suitable laboratory tests and transfusion protocols is highly recommended because the laboratory test guided, protocol-driven transfusion approach reduces blood component utilization, and possibly leads to improved outcomes. Timely assessment of coagulation has been difficult using conventional coagulation tests, but thrombocytopenia, fibrin polymerization defects, and fibrinolysis can be quickly assessed on thromboelastometry. The latter testing can be applied to guide the dosing of fibrinogen and prothrombin complex concentrate, which are selectively used to correct fibrinogen deficiency, and improve thrombin generation in acquired coagulopathy. These therapeutic approaches are novel, and potentially effective in reducing the exposure to allogeneic components (e.g., plasma and platelets) and side-effects of transfusion. Although the accessibility of different therapies among different countries, tranexamic acid is widely available, and is an effective blood conservation measure with a good safety profile in various surgical settings.

SUMMARY

Our understanding of perioperative coagulopathy, diagnostic tools, and therapeutic approaches has evolved in recent years. Additional multidisciplinary efforts are required to understand the optimal combinations, cost-effectiveness, and safety profiles of allogeneic components, and available factor concentrates.

Acute Effect of Intravenous Administration of Magnesium Sulfate on Serum Levels of Interleukin-6 and Tumor Necrosis Factor-α in Patients Undergoing Elective Coronary Bypass Graft With Cardiopulmonary Bypass

Background:

Cardiovascular problems are among the most common health issues. A considerable number of cardiac patients undergo cardiac surgery, and coronary artery disease patients constitute about two-thirds of all these surgeries. The application of cardiopulmonary bypass (CBP) usually results in some untoward effects.

Objectives:

Studies have suggested magnesium sulfate (MgSO4) as an anti-inflammatory agent in a coronary artery bypass graft (CABG). This study aimed to assess the effect of an IV MgSO₄ infusion during elective CABG (with CBP) on the blood levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α).

Materials and Methods:

During a 12 month period, after review board approval and based on inclusion and exclusion criteria, 90 patients were selected and entered randomly into one of the two study groups (MgSO4 or placebo). Anesthesia, surgery and CBP were performed in exactly the same way, except for the use of MgSO4 or a placebo. Both preoperative and postoperative plasma levels of IL-6 and TNF-α were checked and compared between the two groups using an ELISA.

Results:

There was no difference found between the two groups with regard to; gender, basic variables, Ejection Fraction (EF), CBP time and aortic cross-clamp time. The preoperative levels of IL-6 and TNF-α were not different; however, their postoperative levels were significantly higher in the placebo group (P value = 0.01 for IL-6 and 0.005 for TNF-α).

Conclusions:

This study showed that MgSO4 infusion could suppress part of the inflammatory response after CABG with CBP. This was demonstrated by decreased levels of interleukin-6 and TNF-α in postoperative serum levels in elective CABG with CBP.

Fibrinogen concentrate administration attributes to significant reductions of blood loss and transfusion requirements in thoracic aneurysm repair

Background

Repair of thoracic aortic aneurysm (TAA) is often associated with massive hemorrhage aggravated by dilutional coagulopathy with severe hypofibrinogenemia. Although only fresh frozen plasma (FFP) is available for acquired hypofibrinogenemia in Japan, the hemostatic effect of FFP has not been enough for dilutional coagulopathy in TAA surgery. There are increasing reports suggesting that fibrinogen concentrate may be effective in controlling perioperative bleeding and reducing transfusion requirements.

Methods

We retrospectively analyzed the hemostatic effect of fibrinogen concentrate compared with FFP in total 49 cases of elective TAA surgery. In 25 patients, fibrinogen concentrate was administered when the fibrinogen level was below 150 mg/dL at the cardiopulmonary bypass (CPB) termination. The recovery of fibrinogen level, blood loss, and transfused units during surgery were compared between cases of this agent and FFP (n = 24).

Results

We observed rapid increases in plasma fibrinogen level and subsequent improvement in hemostasis by administration of fibrinogen concentrate after CPB termination. The average volume of total blood loss decreased by 64% and the average number of transfused units was reduced by 58% in cases of fibrinogen concentrate given, in comparison with cases of only FFP transfused for fibrinogen supplementation.

Conclusions

In patients showing severe hypofibrinogenemia during TAA surgery, timely administration of fibrinogen concentrate just after removal from CPB is effective for hemostasis, and therefore in reducing blood loss and transfused volumes.

Tranexamic acid and trauma: current status and knowledge gaps with recommended research priorities

A recent large civilian randomized controlled trial on the use of tranexamic acid (TXA) for trauma reported important survival benefits. Subsequently, successful use of TXA for combat casualties in Afghanistan was also reported. As a result of these promising studies, there has been growing interest in the use of TXA for trauma. Potential adverse effects of TXA have also been reported. A US Department of Defense committee conducted a review and assessment of knowledge gaps and research requirements regarding the use of TXA for the treatment of casualties that have experienced traumatic hemorrhage. We present identified knowledge gaps and associated research priorities. We believe that important knowledge gaps exist and that a targeted, prioritized research effort will contribute to the refinement of practice guidelines over time.

Tranexamic acid in remote damage control resuscitation

With the advent of remote damage control resuscitation and far-forward surgery, a renewed emphasis has been placed on examining a variety of pharmacologic adjuncts to controlling blood loss before definitive operative intervention. In this paper, the authors review the current state of the art for tranexamic acid (TXA) and its potential benefits to those patients who are in need of a massive transfusion. Specifically addressed are its biologic and pharmacologic properties, as well the results of a number of recent studies. The 2010 CRASH-2 trial randomized in excess of 20,000 patients and demonstrated a reduction in all-cause mortality from 16.0 to 14.5% and death due to bleeding from 5.7 to 4.9%. The 2012 Military Application of Tranexamic Acid in Trauma Emergency Resuscitation study provided a retrospective analysis of 896 wounded cared for at a military hospital in Afghanistan. This study demonstrated a 23.9%-17.4% reduction in all-cause mortality. Finally, they discuss the potential complications associated with TXA use as well as areas of future research, which are needed to solidify our knowledge of TXA and its potential beneficial effects on controlling bleeding.

High volume image guided injections for the management of chronic tendinopathy of the main body of the Achilles tendon

OBJECTIVES

Several substances are routinely injected in and around tendons. The present study evaluated the long term effects of high volume image guided injection (HVIGI) of normal saline, local anaesthetic and aprotinin in athletic patients with resistant tendinopathy of the main body of the Achilles tendon.

DESIGN

Case series.

METHODS

The study included a series of 94 athletes (69 men and 25 women; average age 37.5 years, range 22-63) with ultrasound confirmed tendinopathy of the main body of the Achilles tendon. All the patients had not improved after at least three months of conservative management. Patients were injected with 10 mL of 0.5% Bupivacaine Hydrochloride, 25 mg aprotinin, and up to 40 mL of injectable normal saline. We prospectively administered the Victorian Institute of Sport Assessment-Achilles tendon (VISA-A) to assess the short- and long-term pain and functional improvement.

RESULTS

At baseline (n = 94), the VISA-A score was 41.7 ± 23.2 (range 11-60), and had improved to 74.6 ± 21.4 (range 71-100) by 12 months (n = 87) (p = 0.003), with no significant difference between sexes.

CONCLUSION

HVIGI with aprotinin significantly reduces pain and improves function in patients with chronic Achilles tendinopathy in the short- and long-term follow up.

Risk factors for postoperative respiratory mortality and morbidity in patients undergoing coronary artery bypass grafting

ABSTRACT

Nowadays, coronary artery bypass grafting (CABG) is considered to be one of the most common surgical procedures. This procedure has been the main topic in many clinical research studies, which have assessed the effect of the procedure on patients’ outcomes. Like other surgical procedures, this procedure is also accompanied by a number of unwanted complications, including those of the respiratory system. Since the respiratory system plays an integral role in defining the clinical outcome of patients, improvements in studies that can assess and predict clinical outcomes of the respiratory system, assume greater importance. There are a number of predictive models which can assess patients in the preoperative period and introduce a number of risk factors, which could be considered as prognostic factors for patients undergoing CABG. The respiratory system is among the clinical systems that are assessed in many prediction scoring systems. This review assesses the main studies which have evaluated the possible risk factors for postoperative respiratory mortality and morbidity, in patients undergoing CABG.

Natural and engineered plasmin inhibitors: applications and design strategies

The serine protease plasmin is ubiquitously expressed throughout the human body in the form of the zymogen plasminogen. Conversion to active plasmin occurs through enzymatic cleavage by plasminogen activators. The plasminogen activator/plasmin system has a well-established function in the removal of intravascular fibrin deposition through fibrinolysis and the inhibition of plasmin activity; this has found widespread clinical use in reducing perioperative bleeding. Increasing evidence also suggests diverse, although currently less defined, roles for plasmin in a number of physiological and pathological processes relating to extracellular matrix degradation, cell migration and tissue remodelling. In particular, dysregulation of plasmin has been linked to cancer invasion/metastasis and various chronic inflammatory conditions; this has prompted efforts to develop inhibitors of this protease. Although a number of plasmin inhibitors exist, they commonly suffer from poor potency and/or specificity of inhibition that either results in reduced efficacy or prevents clinical use. Consequently, there is a need for further development of high-affinity plasmin inhibitors that maintain selectivity over other serine proteases. This review summarises clearly defined and potential applications for plasmin inhibition. The properties of naturally occurring and engineered plasmin inhibitors are discussed in the context of current knowledge regarding plasmin structure, specificity and function. This includes design strategies to obtain the potency and specificity of inhibition in addition to controlled temporal and spatial distribution tailored for the intended use.

Pyrolo[1,2:4,5]-1,4-dioxopyrazino[1,2:1,6]pyrido[3,4-b]indoles: a group of urokinase inhibitors, their synthesis, and stereochemistry-dependent activity

Antifibrinolytic agents are required during complex surgeries to decrease bleeding; their pro-thrombotic potency and efficacy in causing hemostasis has attracted much attention. To discover new inhibitors of urokinase with high selectivity for antifibrinolytic effects over pro-thrombotic effects, the 12-position of (5aS,12S,14aS)- and (5aS,12R,14aS)-5,14-dioxo-1,2,3,5,5a,6,11, 12,14,14a-decahydro-5H,14H-pyrolo[1,2:4,5]pyrazino[1,2:1,6]pyrido[3,4-b]indoles were modified with L-Ala, L-Asp, L-Phe, L-Trp, L-Lys, L-Ser, Gly, and L-Leu to provide 16 (5aS,12S,14aS) and (5aS,12R,14aS) derivatives. In a murine bleeding model, the (5aS,12S,14aS) derivatives containing L-Ala, L-Asp, L-Phe, and L-Trp induced blood coagulation for the treated mice; they also stimulated thrombus formation in a rat thrombosis model, but the other derivatives inhibited thrombosis. The most potent compound, the L-Asp derivative, showed a good therapeutic window: the minimum effective dose for coagulation was <1 nmol kg(-1), whereas at 10 nmol kg(-1), no pro-thrombotic effect was observed. This type of coagulation action was correlated with a mechanism of urokinase inhibition, and these results could lead to the discovery of novel urokinase inhibitors.

From Cerius² based stereoview to mouse and enzyme: the model systems for discovery of novel urokinase inhibitors

Antifibrinolytic therapy during major complex surgery could reduce blood loss and allogeneic transfusion. Novel antagonists of the plasminogen activator and the corresponding model system are of clinical importance. In this paper (1S,2'S,3S)-1-[2-(S)-carboxylindolemethylenemethineaminoeth-1-yl]-2,3,4,5-tetrahydropyrolo[1,2:1,6]pyrazino[3,4:2,3]-1,2,3,4-tetrahydrocarboline-2,5-dione (CIPPC) was presented as a novel antagonist of plasminogen activator, and its blood coagulation and action mechanism were investigated by using a model system which consisted of a mouse-tail bleeding assay, in vitro and in vivo fibrinolysis inhibition assays, a thrombus formation assay and a plasminogen (PLG) electrophoresis assay.

Right atrial thrombosis and pulmonary embolism after atrial septal defect repair

A 3-year-old boy underwent surgical closure of a large ostium secundum atrial septal defect. This was complicated with extensive right atrial thrombus formation and pulmonary thromboembolism immediately following surgery. He was managed with emergency surgical thromboembolectomy and anticoagulation. However, new thrombus was formed again immediately. This prompted us to add thrombolysis to his treatment, but with no effect. He died on the fifth postoperative day. A postmortem study confirmed extensive thromboembolism.

How I treat the acquired von Willebrand syndrome

The acquired von Willebrand syndrome (AVWS) is a bleeding disorder that is frequently unrecognized or is misdiagnosed as von Willebrand disease. AVWS is characterized by structural or functional defects of von Willebrand factor (VWF) that are secondary to autoimmune, lymphoproliferative or myeloproliferative, malignant, cardiovascular, or other disorders. VWF abnormalities in these disorders can result from (1) antibody-mediated clearance or functional interference, (2) adsorption to surfaces of transformed cells or platelets, or (3) increased shear stress and subsequent proteolysis. Diagnosis can be challenging as no single test is usually sufficient to prove or exclude AVWS. Furthermore, there are no evidence-based guidelines for management. Treatments of the underlying medical condition, including chemo/radiotherapy, surgery, or immunosuppressants can result in remission of AVWS, but is not always feasible and successful. Because of the heterogeneous mechanisms of AVWS, more than one therapeutic approach is often required to treat acute bleeds and for prophylaxis during invasive procedures; the treatment options include, but are not limited to, desmopressin, VWF-containing concentrates, intravenous immunoglobulin, plasmapheresis or recombinant factor VIIa. Here, we review the management of AVWS with an overview on the currently available evidence and additional considerations for typical treatment situations.

Coagulation abnormalities in the trauma patient: the role of point-of-care thromboelastography

Current recommendations for resuscitation of the critically injured patient are limited by a lack of point-of-care (POC) assessment of coagulation status. Accordingly, the potential exists for indiscriminant blood component administration. Furthermore, although thromboembolic events have been described shortly after injury, the time sequence of post-injury coagulation changes is unknown. Our current understanding of hemostasis has shifted from a classic view, in which coagulation was considered a chain of catalytic enzyme reactions, to the cell-based model (CBM), representing the interplay between the cellular and plasma components of clot formation. Thromboelastography (TEG), a time-sensitive dynamic assay of the viscoelastic properties of blood, closely parallels the CBM, permitting timely, goal-directed restoration of hemostasis via POC monitoring of coagulation status. TEG-based therapy allows for goal-directed blood product administration in trauma, with potential avoidance of the complications resulting from overzealous component administration, as well as the ability to monitor post-injury coagulation status and thromboprophylaxis. This overview addresses coagulation status and thromboprophylaxis management in the trauma patient and the emerging role of POC TEG.