The safety of aprotinin and lysine-derived antifibrinolytic drugs in cardiac surgery: a meta-analysis

Topical (intra-articular) tranexamic acid reduces blood loss and transfusion rates following total hip replacement: a randomized controlled trial (TRANX-H)

BACKGROUND

Approximately one-third of patients undergoing total hip replacement surgery require one to three units of blood postoperatively. Tranexamic acid is a synthetic antifibrinolytic agent that has been successfully used intravenously to control bleeding after total hip replacement. A topical application is easy to administer, provides a maximum concentration of tranexamic acid at the bleeding site, and is associated with little or no systemic absorption of the tranexamic acid.

METHODS

A double-blind, randomized controlled trial of 161 patients undergoing unilateral primary total hip replacement investigated the effect of topical (intra-articular) application of tranexamic acid on blood loss. The primary outcome was the blood transfusion rate. Secondary outcomes included the drain blood loss, hemoglobin concentration drop, generic quality of life (EuroQol), Oxford Hip Score, length of stay, a cost analysis, and complications.

RESULTS

Tranexamic acid reduced the absolute risk of blood transfusion by 19.6% (95% confidence interval [CI], 6.9% to 32.1%; p = 0.004), from 32.1% to 12.5%, and reduced blood loss by 129 mL (95% CI, 47 to 211 mL; p = 0.002), the hemoglobin concentration drop by 0.84 g/dL (95% CI, 0.41 to 1.27; p < 0.0001), the length of stay by 1.0 days (95% CI, -0.2 to 2.3 days; p = 0.109), and the cost per episode by £305 (95% CI, £0 to £610; p = 0.05). (In 2010, £1 = 1.5 U.S. dollars.) Oxford Hip Scores and EuroQol scores were similar at three months.

CONCLUSIONS

Topically applied tranexamic acid was effective in reducing blood loss and the need for blood transfusion following total hip replacement, avoiding the potential complications of intravenous tranexamic acid administration.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Patent Highlights

Snapshot of key developments in the patent literature of relevance to the advancement of pharmaceutical and medical R&D

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.

[The 2013 Seville Consensus Document on alternatives to allogenic blood transfusion. An update on the Seville Document]

Since allogeneic blood transfusion (ABT) is not harmless, multiple alternatives to ABT (AABT) have emerged, though there is great variability in their indications and appropriate use. This variability results from the interaction of a number of factors, including the specialty of the physician, knowledge and preferences, the degree of anemia, transfusion policy, and AABT availability. Since AABTs are not harmless and may not meet cost-effectiveness criteria, such variability is unacceptable. The Spanish Societies of Anesthesiology (SEDAR), Hematology and Hemotherapy (SEHH), Hospital Pharmacy (SEFH), Critical Care Medicine (SEMICYUC), Thrombosis and Hemostasis (SETH) and Blood Transfusion (SETS) have developed a Consensus Document for the proper use of AABTs. A panel of experts convened by these 6 Societies have conducted a systematic review of the medical literature and have developed the 2013 Seville Consensus Document on Alternatives to Allogeneic Blood Transfusion, which only considers those AABT aimed at decreasing the transfusion of packed red cells. AABTs are defined as any pharmacological or non-pharmacological measure aimed at decreasing the transfusion of red blood cell concentrates, while preserving patient safety. For each AABT, the main question formulated, positively or negatively, is: « Does this particular AABT reduce the transfusion rate or not?» All the recommendations on the use of AABTs were formulated according to the Grades of Recommendation Assessment, Development and Evaluation (GRADE) methodology.

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.

[The 2013 Seville Consensus Document on alternatives to allogenic blood transfusion. An update on the Seville Document]

Since allogeneic blood transfusion (ABT) is not harmless, multiple alternatives to ABT (AABT) have emerged, though there is great variability in their indications and appropriate use. This variability results from the interaction of a number of factors, including the specialty of the physician, knowledge and preferences, the degree of anemia, transfusion policy, and AABT availability. Since AABTs are not harmless and may not meet cost-effectiveness criteria, such variability is unacceptable. The Spanish Societies of Anesthesiology (SEDAR), Hematology and Hemotherapy (SEHH), Hospital Pharmacy (SEFH), Critical Care Medicine (SEMICYUC), Thrombosis and Hemostasis (SETH) and Blood Transfusion (SETS) have developed a Consensus Document for the proper use of AABTs. A panel of experts convened by these 6 Societies have conducted a systematic review of the medical literature and have developed the 2013 Seville Consensus Document on Alternatives to Allogeneic Blood Transfusion, which only considers those AABT aimed at decreasing the transfusion of packed red cells. AABTs are defined as any pharmacological or non-pharmacological measure aimed at decreasing the transfusion of red blood cell concentrates, while preserving patient safety. For each AABT, the main question formulated, positively or negatively, is: "Does this particular AABT reduce the transfusion rate or not?" All the recommendations on the use of AABTs were formulated according to the Grades of Recommendation Assessment, Development and Evaluation (GRADE) methodology.

Pharmacologic tools to reduce bleeding in surgery

Strategies to reduce blood loss and the need for transfusions in surgery include enhancement of coagulation, inhibition of fibrinolysis, and an improved decision algorithm for transfusion based on bedside monitoring of global hemostasis. The synthetic antifibrinolytic drug tranexamic acid has emerged as an effective alternative in this respect for orthopedic and cardiac surgery. Although it seems less effective than aprotinin, it has not been associated with the increased risk of mortality of the latter. Thromboelastography to monitor the global hemostatic capacity and to guide the appropriate use of blood components in cardiac surgery is also effective in reducing the need for transfusion. Patients on antithrombotic drug therapy may need reversal before surgery to avoid excessive blood loss, or intraoperatively in cases of unexpected bleeding. Available options are protamine for unfractionated or low-molecular-weight heparin, recombinant activated factor VII for fondaparinux, prothrombin complex concentrate for vitamin K antagonists and possibly for oral factor Xa inhibitors, dialysis and possibly activated prothrombin complex concentrate for oral thrombin inhibitors, desmopressin for aspirin and possibly for thienopyridines, and platelet transfusions for the latter.

Hyperfibrinolysis after parapelvic cyst surgery: A case report

The present study describes the diagnosis and treatment of hyperfibrinolysis following surgery in a 25-year-old female patient. An examination revealed that the left kidney had been affected by severe hydronephrosis for two weeks prior to hospitalization. The diagnosis of a parapelvic cyst was obtained by preoperative intravenous pyelogram (IVP), computed tomography (CT) and upper left urinary tract retrograde pyelography. Unroofing of the left parapelvic cyst was performed by open surgery. The patient exhibited symptoms of shock 48 h later, and her hemoglobin (Hb) levels dropped to only 62.2 g/l. To treat this, 400 ml erythrocyte suspension transfusion was administered 3 times every other day. The patient's Hb levels remained between 50 and 60 g/l. The D-dimer assay index rose from 0.3 to 16 mg/l and the fibrin degradation product (FDP) levels progressively increased following the hemorrhage, while the platelet count, prothrombin time (PT), activated partial thromboplastin time (APTT) and fibrinogen (Fg) index were all within normal levels. p-Aminomethylbenzoic acid (PAMBA; 0.5 g) was administered to the patient every day, and as a consequence the Hb levels rose steadily from the next day onwards. After a one week course of PAMBA treatment, the patient's condition became stable. Blood coagulation and fibrinolytic function measurements were all within the normal ranges in the three months following the surgery. Delayed hemorrhage following surgery should be considered as a possible cause of hyperfibrinolysis. Monitoring FDP and D-dimer levels may aid a rapid and clear diagnosis. Anti-fibrinolytic therapy, such as PAMBA treatment, is safe and effective for use against the type of hemorrhage caused by hyperfibrinolysis.

Moderate dosage of tranexamic acid during cardiac surgery with cardiopulmonary bypass and convulsive seizures: incidence and clinical outcome

BACKGROUND

Convulsive seizures (CS) occur in ∼1% of the patients after cardiac surgery with cardiopulmonary bypass. Recent investigations indicate an up to seven-fold increase in CS in cardiac surgical patients receiving high doses (≥60 mg kg(-1) body weight) of tranexamic acid (TA).

METHODS

In a retrospective data analysis of 4883 cardiac surgical patients, we investigated the incidence of CS in patients receiving a moderate dose of TA (24 mg kg(-1) body weight) compared with a reference group not receiving TA as a primary endpoint. Secondary endpoints were intensive care unit stay and in-hospital mortality. We performed propensity score (PS)-adjusted logistic regression analysis to test the association between TA use/non-use and clinical outcomes.

RESULTS

Compared with the reference group, the PS-adjusted odds ratio (OR) for CS in the TA group was 1.703 [95% confidence interval (CI): 1.01-2.87; P=0.045; incidence 2.5% vs 1.2%]. Log-ICU-stay was significantly longer (P=0.004) and PS-adjusted relative in-hospital mortality risk was significantly higher for the TA group compared with the reference group (OR=1.89; 95% CI: 1.21-2.96; P=0.005). Both the TA-associated CS incidence and the in-hospital mortality risk were only significant in patients undergoing open-heart surgery (OR=2.034, 95% CI: 1.07-3.87; P=0.034 and OR=2.20, 95% CI: 1.32-3.69; P=0.003, respectively) but not in patients undergoing coronary artery bypass grafting (OR=1.21, 95% CI: 0.49-3.03; P=0.678 and OR=1.13, 95% CI: 0.42-3.02; P=0.809, respectively).

CONCLUSIONS

In open-heart surgery, even moderate TA doses are associated with a doubled rate of CS and in-hospital mortality. Prospective trials are needed to further evaluate the safety profile of TA in cardiac surgery.

Criteria for empiric treatment of hyperfibrinolysis after trauma

BACKGROUND

Recent studies identify a survival benefit from the administration of antifibrinolytic agents in patients with severe injury and trauma. However, identification of hyperfibrinolysis requires thromboelastography, which is not widely available. We hypothesized that analysis of patients with thromboelastography-diagnosed hyperfibrinolysis would identify clinical criteria for empiric antifibrinolytic treatment in the absence of thromboelastography.

METHODS

From November 2010 to March 2012, serial blood samples were collected from 115 patients with critical injury on arrival to the emergency department of an urban Level I trauma center. Rotational thromboelastography was performed to assess viscoelastic properties of clot formation in the presence and absence of aprotinin to identify treatable hyperfibrinolysis. For 20 patients identified with treatable hyperfibrinolysis, clinical predictors were investigated using receiver operating characteristic analysis.

RESULTS

Of the 115 patients evaluated, 20% had hyperfibrinolysis, defined as an admission maximal clot lysis of 10% or higher, reversible by aprotinin treatment. Patients with hyperfibrinolysis had significantly lower temperature, pH, and platelet counts and higher international normalized ratio, activated partial thromboplastin time, and D-dimer. Hyperfibrinolysis was associated with multiorgan failure (63.2% vs. 24.6%, p = 0.004) and mortality (52.2% vs. 12.9%, p < 0.001). We then evaluated all non-rotational thromboelastography clinical and laboratory parameters predictive of hyperfibrinolysis using receiver operating characteristic analysis to evaluate potential empiric treatment guidelines. The presence of hypothermia (temperature ≤36.0°C), acidosis (pH ≤7.2), relative coagulopathy (international normalized ratio ≥1.3 or activated partial thromboplastin time ≥30), or relative thrombocytopenia (platelet count ≤200) identified hyperfibrinolysis with 100% sensitivity and 55.4% specificity (area under the curve, 0.777).

CONCLUSION

Consideration of empiric antifibrinolytic therapy is warranted for patients with critical injury and trauma who present with acidosis, hypothermia, coagulopathy, or relative thrombocytopenia. These clinical predictors identified hyperfibrinolysis with 100% sensitivity while simultaneously eliminating 46.6% of inappropriate therapy compared with the empiric treatment of all injured patients. These criteria will facilitate empiric treatment of hyperfibrinolysis for clinicians without access to thromboelastography.

LEVEL OF EVIDENCE

Prognostic study, level III.

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.

Fibrin chain cross-linking, fibrinolysis, and in vivo sealing efficacy of differently structured fibrin sealants

In this study, we compared the sealing characteristics and efficacy of a fibrin sealant with reduced plasminogen (FS-rplg) and a fibrin sealant with aprotinin as a fibrinolysis inhibitor (FS-apr). The relevant sealing characteristics including clot structure, fibrin chain cross-linking, and clot lysis were tested in the laboratory. The sealing efficacy was then investigated in a follow-up animal model to determine differences in the in vivo sealing properties. A total of 46 animals were available for the final analysis with 23 animals in each treatment arm. In conclusion, we saw differences in vitro between FS-rplg and FS-apr in ultrastructure and α-chain cross-linking rates as well as in the rate of fibrinolysis. These differences may explain the significantly enhanced sealing efficacy in FS-apr compared to FS-rplg shown in vivo in a rabbit intestinal model.

Tranexamic acid reduces blood transfusions in elderly patients undergoing combined aortic valve and coronary artery bypass graft surgery: a randomized controlled trial

OBJECTIVE

To evaluate the effects of tranexamic acid on postoperative blood loss and transfusion requirements in elderly patients undergoing combined aortic valve replacement and coronary artery bypass graft surgery (CABG).

DESIGN

A prospective, randomized, double-blinded, placebo-controlled, parallel-group trial.

SETTING

A university hospital (single institution).

PARTICIPANTS

Sixty-four patients 70 years or older undergoing combined aortic valve replacement and CABG surgery were included. One patient was withdrawn from the study after randomization by the attending surgeon because of a change in the surgical procedure. The remaining 63 patients were analyzed as intention to treat.

INTERVENTIONS

The included patients were randomized to treatment with either tranexamic acid, 10 mg/kg, as a bolus injection before surgery followed by 1 mg/kg/h as an infusion during surgery, or a corresponding volume of 0.9% sodium chloride.

MEASUREMENTS AND MAIN RESULTS

Postoperative blood loss was recorded for 16 hours. The transfusion of blood products was recorded during the entire hospital stay. The number of packed red cell transfusions given to the patients was significantly lower in the tranexamic acid group compared with the placebo group (median, 3.0 [interquartile range, 2-5] v 5.0 [3-7], p = 0.049).

CONCLUSION

Tranexamic acid reduced the number of packed red cell transfusions given to patients 70 years or older undergoing combined aortic valve replacement and CABG surgery.

Aprotinin, transfusions, and kidney injury in neonates and infants undergoing cardiac surgery

BACKGROUND

A significantly increased risk of acute kidney injury (AKI) with the prophylactic use of aprotinin has been reported in adults undergoing cardiac surgery, but not in children. Blood product transfusions have also been shown to carry an independent risk of AKI. The present study assessed associations between AKI, aprotinin, and transfusions in neonates and infants undergoing cardiac surgery.

METHODS

All neonates and infants undergoing surgery with cardiopulmonary bypass over a 42 month period, before and after the withdrawal of aprotinin, were included retrospectively. AKI was assessed by the Acute-Kidney-Injury-Network classifications. A propensity score was used to balance treated and untreated groups.

RESULTS

Three hundred and ninety patients received aprotinin and 568 patients did not. Inverse probability of treatment weighting resulted in good balance between groups for baseline and surgical characteristics. Controls underwent surgery with smaller bypass circuits and fewer transfusions. After adjustment for the use of miniaturized circuits and for the year of surgery, no significant association between the incidence of AKI, dialysis, and aprotinin was noted. Red blood cell transfusions were associated with an increased risk of AKI and dialysis: odds ratios (ORs) 1.64 (1.12-2.41) and 2.07 (1.13-3.73), respectively; as were fresh frozen plasma transfusions, ORs 2.28 (1.68-3.09) and 3.11 (1.95-4.97), respectively. Platelet transfusions were associated with an increased risk of dialysis: OR 2.20 (1.21-4.01).

CONCLUSIONS

Blood product transfusions, but not the prophylactic use of aprotinin, are significantly associated with AKI after cardiac surgery in neonates and infants.

The effect of ulinastatin on postoperative blood loss in patients undergoing open heart surgery with cardiopulmonary bypass

This prospective, randomized, double-blind study evaluated the effect of ulinastatin on postoperative blood loss and transfusion requirements of patients undergoing open-heart surgery with cardiopulmonary bypass (CPB) and aortic cross-clamping (ACC). CPB and ACC produce variable systemic inflammatory reactions that are associated with multiorgan dysfunction via leucocytes, especially polymorphonuclear neutrophils (PMNs). PMNs increase blood loss and transfusion requirements. Ulinastatin, a urinary trypsin inhibitor, inhibits PMN activity and reduces the systemic inflammatory response. Patients received either 5000 U/kg ulinastatin or the equivalent volume of normal saline (control group) before ACC. Postoperative blood loss and transfusion requirements were recorded. Duration of intubation and length of stay in the intensive care unit (ICU) were also noted. There were no statistically significant between-group differences in postoperative blood loss and transfusion requirements. Ulinastatin caused a non-significant decrease in duration of intubation. Patients who received ulinastatin had significantly shorter ICU stays than control patients.

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.

Cardiopulmonary Bypass, Inflammation and How to Defy it: Focus on Pharmacological Interventions

One of the most common health problems are diseases of the cardiovascular system with a great bulk of disease burden; while a considerable number of cardiac patients undergo cardiac surgery; cardiac surgical procedures with cardiopulmonary bypass (CPB) are nowadays among the top list of surgical procedures. More than half of a century has passed since the introduction of total cardiopulmonary bypass (CPB). One of the main untoward effects of CPB is systemic inflammation; causing an "acute phase reaction" responsible for the production of other unwanted postoperative complications. The humoral and cellular components of the immune system are among the main parts of these compensatory mechanisms. There are a number of therapeutic agents used to suppress this inflammatory process. Since CPB is composed of a multitude of items, there are many studies assessing the possible methods and therapeutics for prevention or treatment of inflammation in patients undergoing CPB. According to a conventional classification, the anti-inflammatory methods are classified as either pharmacologic strategies or technical strategies. The pharmacologic strategies are those with the usage of one or more therapeutic agents; while the technical strategies are those that try to modify the CPB techniques. However, in this manuscript, the main pharmacological strategies are discussed.

Low dose aprotinin increases mortality and morbidity in coronary artery bypass surgery(*)

BACKGROUND

The low dose aprotinin consistently reduces blood and transfusion requirement in adults during cardiac surgical procedures but its effectiveness in some ethnical groups were debated and controversy about its effect on mortality and morbidity precludes its routine use. This study was designated to determine whether a low dose of aprotinin causes more mortality and morbidity when used after coronary artery bypass grafting (CABG) surgery.

METHODS

In a clinical trial study, 380 patients in placebo and 273 patients in aprotinin group were enrolled. A test dose before skin incision and 2 million kallikrein inactivation units (KIU) during initiation of cardiopulmonary bypass (CPB) were given to patients. Differences in quantity of blood transfusion, morbidity and mortality were analyzed. Multivariable analysis was performed to determine risk factors for mortality.

RESULTS

Decreased blood product transfusions and increased rate of morbidity were found in the aprotinin group. Independent predictors for increased number of transfusion were aspirin continued before operation and small body mass index (BMI) but there was a significant difference in mortality and morbidity between two groups.

CONCLUSIONS

In patients undergoing CABG procedure, low dose aprotinin is effective in attenuating post bypass coagulopathy and decreasing blood product use, but it increases morbidity.

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.

Detrimental effect of aprotinin ban on amount of blood loss during liver transplantation: single-center experience

BACKGROUND

Aprotinin, a plasmin inhibitor, had been used for reduction of intraoperative bleeding caused by hyperfibrinolysis during extensive surgery. Prophylaxis with aprotinin to limit blood loss during orthotopic liver transplantation (OLT) had been widely applied until the drug was weaned off the therapeutic list for severe complications. We compared the need for blood and blood products transfusion in patients undergoing OLT with and without the use of aprotinin.

MATERIALS AND METHODS

A retrospective analysis was performed on 150 patients, who underwent OLT between March 2004 and August 2008 and were divided into 2 groups: the APRO group (n = 111) after induction of anesthesia was given a bolus of 500 kIU of aprotinin in a 30-minutes infusion followed by 140 kIU/h till the end of the OLT in which aprotinin was not administered, and the NON-APRO group (n = 39).

RESULTS

Patients from the NON-APRO group needed significantly more units of packed red blood cells (PRBC) than the APRO group (5.53 ± 4.89 vs 3.99 ± 3.58 units; P = .037). Avoidance of aprotinin administration (β = 1.408), Child-Pugh score (β = 0.519), and duration of anhepatic phase (β = 0.03) affected the volume of transfused blood according to multiple regression analysis (P < .05).

CONCLUSIONS

Our study confirmed the important prophylactic role aprotinin used to have during OLT in limiting the need for blood transfusions. Further research and progress in methods of blood loss minimization and monitoring of hemostasis are needed to warrant safe liver transplantation.

Tranexamic acid reduces blood loss after off-pump coronary surgery: a prospective, randomized, double-blind, placebo-controlled study

BACKGROUND

Bleeding and the need for allogeneic transfusions are still problems after off-pump coronary artery bypass grafting (OPCAB) surgery. We therefore evaluated the effects of an antifibrinolytic, tranexamic acid, on postoperative bleeding and transfusion requirements in patients undergoing OPCAB surgery.

METHODS

Two hundred thirty-one consecutive patients scheduled for elective OPCAB were enrolled in the study. Using a double-blind method, the patients were randomly assigned to receive either tranexamic acid (bolus 1 g before surgical incision followed by an infusion of 400 mg/h during surgery; n = 116) or a placebo (infusion equivalent volume of saline solution; n = 115). The primary outcome was 24-hour postoperative chest tube drainage. Allogeneic transfusion, mortality, major morbidities, and resource utilization were also recorded.

RESULTS

In comparison with the placebo group, the patients receiving tranexamic acid had a significant reduction in chest tube drainage at 6 hours (270 ± 118 mL vs 416 ± 179 mL, P < 0.001) and 24 hours (654 ± 224 mL vs 891 ± 295 mL, P < 0.001). There was also a significant reduction in allogeneic red blood cell transfusions (47 vs 31.9%, P = 0.019) and fresh frozen plasma (29.6% vs 17.2%, P = 0.027) transfusions. There were no differences in mortality, morbidity, and resource utilization between the 2 groups.

CONCLUSIONS

Tranexamic acid reduces postoperative chest tube drainage and the requirement for allogeneic transfusion in off-pump coronary surgery.

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.

Blood-saving techniques

Major surgery is associated with intraoperative and postoperative bleeding, generally treated with homologous blood transfusions, which carry the risk of infection, allergic reactions, or incompatibility as well as a number of organizational and economic problems. Transfusion strategies and steps to minimize perioperative bleeding are needed. Another resource is drugs; human recombinant erythropoietin, aprotinin, and some analogues of lysine have been used to reduce the rate of allogenic transfusions in the perioperative period. The safest method is autologous blood transfusions through predeposits and hemodilution; however, it can only be used for elective surgery. Autologous transfusion techniques include blood collection, both intraoperatively, as described by Orr, and postoperatively, as introduced by Borghi in 1984, which enables the continuous monitoring of postoperative bleeding. Blood collection can also be performed during emergency surgery, reducing the rate and costs of homologous transfusions.

Ferraris VA, Brown JR, Despotis GJ, Hammon JW, Reece TB, Saha SP, Song HK, Clough ER, Shore-Lesserson LJ, Goodnough LT, Mazer CD, Shander A, Stafford-Smith M, Waters J, Baker RA, Dickinson TA, FitzGerald DJ, Likosky DS, Shann KG. 2011 update to the Society of Thoracic Surgeons and the Society of Cardiovascular Anesthesiologists blood conservation clinical practice guidelines

BACKGROUND

Practice guidelines reflect published literature. Because of the ever changing literature base, it is necessary to update and revise guideline recommendations from time to time. The Society of Thoracic Surgeons recommends review and possible update of previously published guidelines at least every three years. This summary is an update of the blood conservation guideline published in 2007.

METHODS

The search methods used in the current version differ compared to the previously published guideline. Literature searches were conducted using standardized MeSH terms from the National Library of Medicine PUBMED database list of search terms. The following terms comprised the standard baseline search terms for all topics and were connected with the logical 'OR' connector--Extracorporeal circulation (MeSH number E04.292), cardiovascular surgical procedures (MeSH number E04.100), and vascular diseases (MeSH number C14.907). Use of these broad search terms allowed specific topics to be added to the search with the logical 'AND' connector.

RESULTS

In this 2011 guideline update, areas of major revision include: 1) management of dual anti-platelet therapy before operation, 2) use of drugs that augment red blood cell volume or limit blood loss, 3) use of blood derivatives including fresh frozen plasma, Factor XIII, leukoreduced red blood cells, platelet plasmapheresis, recombinant Factor VII, antithrombin III, and Factor IX concentrates, 4) changes in management of blood salvage, 5) use of minimally invasive procedures to limit perioperative bleeding and blood transfusion, 6) recommendations for blood conservation related to extracorporeal membrane oxygenation and cardiopulmonary perfusion, 7) use of topical hemostatic agents, and 8) new insights into the value of team interventions in blood management.

CONCLUSIONS

Much has changed since the previously published 2007 STS blood management guidelines and this document contains new and revised recommendations.

Treatment and monitoring of coagulation abnormalities in children undergoing heart surgery

Bleeding is a considerable clinical problem during and after pediatric heart surgery. While the primary cause of bleeding is surgical trauma, its treatment is often complicated by the presence of coagulopathy. The principle causes of coagulopathy are discussed to provide a context for treatment. The role of laboratory and point of care tests, which aim to identify the cause of bleeding in the individual patient, is also discussed. An attempt is made to examine the current evidence for available therapies, including use of blood products and, more recently proposed, approaches based on human or recombinant factor concentrates.

Platelet-rich-plasmapheresis for minimising peri-operative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have generated considerable enthusiasm for the use of technologies intended to reduce the use of allogeneic blood (blood from an unrelated donor). Platelet-rich plasmapheresis (PRP) offers an alternative approach to blood conservation.

OBJECTIVES

To examine the evidence for the efficacy of PRP in reducing peri-operative allogeneic red blood cell (RBC) transfusion, and the evidence for any effect on clinical outcomes such as mortality and re-operation rates.

SEARCH STRATEGY

We identified studies by searching MEDLINE (1950 to 2009), EMBASE (1980 to 2009), The Cochrane Library (Issue 1, 2009), the Internet (to March 2009) and the reference lists of published articles, reports, and reviews.

SELECTION CRITERIA

Controlled parallel group trials in which adult patients, scheduled for non-urgent surgery, were randomised to PRP, or to a control group which did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Primary outcomes measured were: the number of patients exposed to allogeneic RBC transfusion, and the amount of RBC transfused. Other outcomes measured were: the number of patients exposed to allogeneic platelet transfusions, fresh frozen plasma, and cryoprecipitate, blood loss, re-operation for bleeding, post-operative complications (thrombosis), mortality, and length of hospital stay. Treatment effects were pooled using a random-effects model. Trial quality was assessed using criteria proposed by Schulz et al (Schulz 1995).

MAIN RESULTS

Twenty-two trials of PRP were identified that reported data for the number of patients exposed to allogeneic RBC transfusion. These trials evaluated a total of 1589 patients. The relative risk (RR) of exposure to allogeneic blood transfusion in those patients randomised to PRP was 0.73 (95%CI 0.59 to 0.90), equating to a relative risk reduction (RRR) of 27% and a risk difference (RD) of 19% (95%CI 10% to 29%). However, significant heterogeneity of treatment effect was observed (p < 0.00001; I² = 79%). When the four trials by Boldt are excluded, the RR is 0.76 (95% CI 0.62 to 0.93). On average, PRP did not significantly reduce the total volume of RBC transfused (weighted mean difference [WMD] -0.69, 95%CI -1.93 to 0.56 units). Trials provided inadequate data regarding the impact of PRP on morbidity, mortality, and hospital length of stay. Trials were generally small and of poor methodological quality.

AUTHORS' CONCLUSIONS

Although the results suggest that PRP is effective in reducing allogeneic RBC transfusion in adult patients undergoing elective surgery, there was considerable heterogeneity of treatment effects and the trials were of poor methodological quality. The available studies provided inadequate data for firm conclusions to be drawn regarding the impact of PRP on clinically important endpoints.

The clinical effects of red blood cell transfusions: an overview of the randomized controlled trials evidence base

No up-to-date overview of randomized controlled trials (RCTs) in red blood cell (RBC) transfusion exists. This systematic review examines the quantity and quality of the evidence for the clinical effects of RBC transfusion. One hundred forty-two eligible RCTs were identified through searches of The Cochrane Library (issue 4, 2009), MEDLINE (1950 to November 2009), EMBASE (1974 to November 2009), and other relevant sources. After data extraction and methodological quality assessment, trials were grouped by clinical specialty and type of RBC transfusion. Data analysis was predominantly descriptive. The 142 RCTs covered 11 specialties and 10 types of RBC transfusion. The number of included patients varied widely across the RCTs (median, 57; IQ range, 27-167). Most trials were single center comparing 2 parallel study arms. Overall, the reporting of methodological assessment was poor, although it improved markedly from 2001. Clinical areas with few trials are highlighted. Comparison with a study of RBC use in clinical practice highlighted a lack of correlation between the size of the evidence base for a given clinical specialty and the proportion of total RBC use by that clinical specialty. The gaps in the evidence base and the poor methodology of trials particularly in the past do not provide a strong evidence base for the use of RBC transfusions, but they indicate important targets for future research.

Plasmin inhibitors prevent leukocyte accumulation and remodeling events in the postischemic microvasculature

Clinical trials revealed beneficial effects of the broad-spectrum serine protease inhibitor aprotinin on the prevention of ischemia-reperfusion (I/R) injury. The underlying mechanisms remained largely unclear. Using in vivo microscopy on the cremaster muscle of male C57BL/6 mice, aprotinin as well as inhibitors of the serine protease plasmin including tranexamic acid and ε-aminocaproic acid were found to significantly diminish I/R-elicited intravascular firm adherence and (subsequent) transmigration of neutrophils. Remodeling of collagen IV within the postischemic perivenular basement membrane was almost completely abrogated in animals treated with plasmin inhibitors or aprotinin. In separate experiments, incubation with plasmin did not directly activate neutrophils. Extravascular, but not intravascular administration of plasmin caused a dose-dependent increase in numbers of firmly adherent and transmigrated neutrophils. Blockade of mast cell activation as well as inhibition of leukotriene synthesis or antagonism of the platelet-activating-factor receptor significantly reduced plasmin-dependent neutrophil responses. In conclusion, our data suggest that extravasated plasmin(ogen) mediates neutrophil recruitment in vivo via activation of perivascular mast cells and secondary generation of lipid mediators. Aprotinin as well as the plasmin inhibitors tranexamic acid and ε-aminocaproic acid interfere with this inflammatory cascade and effectively prevent postischemic neutrophil responses as well as remodeling events within the vessel wall.

High-dose tranexamic acid is related to increased risk of generalized seizures after aortic valve replacement

OBJECTIVE

To investigate the incidence of postoperative generalized seizures in patients undergoing aortic valve replacement (AVR) under extracorporeal circulation, who received either high-dose tranexamic acid (TXA) or epsilon aminocaproic acid (EACA) as an antifibrinolytic agent.

METHODS

This retrospective analysis comprised 682 consecutive patients undergoing AVR with or without simultaneous coronary artery bypass surgery. Patients operated on before March 2008 were treated intra-operatively with TXA (100 mg kg⁻¹; n = 341), patients operated on after March 2008 received EACA (50 mg kg⁻¹ loading dose, followed by 25 mg kg⁻¹ h⁻¹, and an additional 5 g in the extracorporeal circuit; n = 341).

RESULTS

Clinically diagnosed generalized seizures were observed within the first 24h postoperatively, more frequently in patients receiving TXA compared with EACA (6.4% vs 0.6%, p < 0.001, difference = 5.8%, 95% confidence interval 3.1-8.5%). Besides the antifibrinolytic agent, three other variables differed significantly between patients with and without postoperative seizures: age (mean (SD), 77.0 (5.9) years vs 73.2 (9.0) years, p = 0.039), preoperative creatinine clearance (55.4 (16.5)ml min⁻¹ vs 72.6 (28.5)ml min⁻¹, p = 0.002), and administration of recombinant activated factor VIIa (3 out of 24 patients (12.5%) vs 8 out of 658 patients (1.2%), p = 0.005). Logistic regression analysis demonstrated a significant impact of the antifibrinolytic drug, creatinine clearance, and the application of recombinant activated factor VIIa on the occurrence of generalized seizures.

CONCLUSIONS

Our results indicate that high-dose TXA is associated with an increased incidence of postoperative generalized seizures in patients undergoing AVR compared with EACA, especially when suffering from renal impairment. A possible association between recombinant activated factor VIIa and the occurrence of postoperative seizures needs further investigation.