Perioperative systemic haemostatic agents

Unravelling the Antifibrinolytic Mechanism of Action of the 1,2,3-Triazole Derivatives

A new family of antifibrinolytic drugs has been recently discovered, combining a triazole moiety, an oxadiazolone, and a terminal amine. Two of the molecules of this family have shown activity that is greater than or similar to that of tranexamic acid (TXA), the current antifibrinolytic gold standard, which has been associated with several side effects and whose use is limited in patients with renal impairment. The aim of this work was to thoroughly examine the mechanism of action of the two ideal candidates of the 1,2,3-triazole family and compare them with TXA, to identify an antifibrinolytic alternative active at lower dosages. Specifically, the antifibrinolytic activity of the two compounds (1 and 5) and TXA was assessed in fibrinolytic isolated systems and in whole blood. Results revealed that despite having an activity pathway comparable to that of TXA, both compounds showed greater activity in blood. These differences could be attributed to a more stable ligand-target binding to the pocket of plasminogen for compounds 1 and 5, as suggested by molecular dynamic simulations. This work presents further evidence of the antifibrinolytic activity of the two best candidates of the 1,2,3-triazole family and paves the way for incorporating these molecules as new antifibrinolytic therapies.

Updated Clinical Review: Perioperative Use of Tranexamic Acid in Orthopedics and Other Surgeries

Tranexamic acid is a well-known antifibrinolytic that has numerous clinical indications, and it is efficacious and safe in many perioperative scenarios including patients with some thrombotic risks. However, further studies that characterize clinical outcomes concerning dosing, timing, and routes in combination are needed in ultra high-risk populations.

Aprotinin-Drug against Respiratory Diseases

Aprotinin (APR) was discovered in 1930. APR is an effective pan-protease inhibitor, a typical "magic shotgun". Until 2007, APR was widely used as an antithrombotic and anti-inflammatory drug in cardiac and noncardiac surgeries for reduction of bleeding and thus limiting the need for blood transfusion. The ability of APR to inhibit proteolytic activation of some viruses leads to its use as an antiviral drug for the prevention and treatment of acute respiratory virus infections. However, due to incompetent interpretation of several clinical trials followed by incredible controversy in the literature, the usage of APR was nearly stopped for a decade worldwide. In 2015-2020, after re-analysis of these clinical trials' data the restrictions in APR usage were lifted worldwide. This review discusses antiviral mechanisms of APR action and summarizes current knowledge and prospective regarding the use of APR treatment for diseases caused by RNA-containing viruses, including influenza and SARS-CoV-2 viruses, or as a part of combination antiviral treatment.

Therapeutic use of α2-antiplasmin as an antifibrinolytic and hemostatic agent in surgery and regenerative medicine

The biomaterial fibrin is widely used as a clinical tissue sealant in surgery. In preclinical research, fibrin is also extensively studied as a carrier material for growth factor delivery. In these applications, premature fibrin degradation leads to recurrent bleeding, tissue dehiscence and limited regenerative efficacy. Therefore, fibrinolysis inhibitors have been added to clinical fibrin formulations, for example the bovine-derived serine protease inhibitor aprotinin. Aprotinin is additionally used as a hemostatic agent to prevent excessive bleeding during surgery, in this case protecting endogenous fibrin clots. Nevertheless, aprotinin use has been associated with serious safety issues. Here, we explore the use the human physiological fibrinolysis inhibitor α2-antiplasmin (α2PI) as a substitute for aprotinin. We evaluate the efficacy of α2PI in the three main applications of aprotinin. We first showed that recombinant α2PI can successfully prolong the durability of fibrin biomaterials as compared to aprotinin in a model of subcutaneous implantation in mice mimicking application as a tissue sealant. We then used α2PI to enhance the delivery of engineered vascular endothelial growth factor (VEGF)-A and platelet-derived growth factor (PDGF)-BB in fibrin in promoting diabetic wound healing, which lead to improved wound closure, granulation tissue formation and angiogenesis. Lastly, we demonstrated that α2PI can be as effective as aprotinin as an intravenous hemostatic agent to prevent blood loss, using a tail-vein bleeding model in mice. Therefore, we believe that engineering fibrin biomaterials or endogenous fibrin with α2PI can have a strong impact in surgery and regenerative medicine by providing a competitive substitute to aprotinin that is of human origin.

Engineered Molecular Therapeutics Targeting Fibrin and the Coagulation System: a Biophysical Perspective

The coagulation cascade represents a sophisticated and highly choreographed series of molecular events taking place in the blood with important clinical implications. One key player in coagulation is fibrinogen, a highly abundant soluble blood protein that is processed by thrombin proteases at wound sites, triggering self-assembly of an insoluble protein hydrogel known as a fibrin clot. By forming the key protein component of blood clots, fibrin acts as a structural biomaterial with biophysical properties well suited to its role inhibiting fluid flow and maintaining hemostasis. Based on its clinical importance, fibrin is being investigated as a potentially valuable molecular target in the development of coagulation therapies. In this topical review, we summarize our current understanding of the coagulation cascade from a molecular, structural and biophysical perspective. We highlight single-molecule studies on proteins involved in blood coagulation and report on the current state of the art in directed evolution and molecular engineering of fibrin-targeted proteins and polymers for modulating coagulation. This biophysical overview will help acclimatize newcomers to the field and catalyze interdisciplinary work in biomolecular engineering toward the development of new therapies targeting fibrin and the coagulation system.

Synthesis and Hemostatic Activity of New Amide Derivatives

Eight dipeptides containing antifibrinolytic agents (tranexamic acid, aminocaproic acid, 4-(aminomethyl)benzoic acid, and glycine—natural amino acids) were synthesized in a three-step process with good or very good yields. DMT/NMM/TsO⁻ (4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium toluene-4-sulfonate) was used as a coupling reagent. Hemolysis tests were used to study the effects of the dipeptides on blood components. Blood plasma clotting tests were used to examine their effects on thrombin time (TT), prothrombin time (PT), and the activated partial thromboplastin time (aPTT). The level of hemolysis did not exceed 1%. In clotting tests, TT, PT, and aPTT did not differentiate any of the compounds. The prothrombin times for all amides 1–8 were similar. The obtained results in the presence of amides 1–4 and 8 were slightly lower than for the other compounds and the positive control, and they were similar to the results obtained for TA. In the case of amide 3, a significantly decreased aPTT was observed. The aPTTs observed for plasma treated with amide 3 and TA were comparable. In the case of amide 6 and 8, TT values significantly lower than for the other compounds were found. The clot formation and fibrinolysis (CFF) assay was used to assess the influence of the dipeptides on the blood plasma coagulation cascade and the fibrinolytic efficiency of the blood plasma. In the clot formation and fibrinolysis assay, amides 5 and 7 were among the most active compounds. The cytotoxicity and genotoxicity of the synthesized dipeptides were evaluated on the monocyte/macrophage peripheral blood cell line. The dipeptides did not cause hemolysis at any concentrations. They exhibited no significant cytotoxic effect on SC cells and did not induce significant DNA damage.

Use of tranexamic acid in bleeding control of transabdominal and transvaginal hysterectomy

Background:

Hysterectomy is one of the most common gynecology surgeries. This study aimed to compare perioperative bleeding in transabdominal and transvaginal hysterectomy.

Materials and Methods:

This prospective, double-blind, randomized, controlled clinical trial was performed on 80 patients undergoing hysterectomy referred to Shahid Beheshti Hospital, Isfahan, Iran. Patients were divided into two groups of 40; the first group (T) received 1 g intravenous tranexamic acid (TXA) for 20 min preoperatively. The second group (S) received 10 cc normal saline as placebo. Blood samples were taken before and 12 h after surgery for assessment of hemoglobin, hematocrit, and platelet count, the prothrombin time, activated partial thromboplastin time, and serum creatinine as well as volume of blood transfusion.

Results:

There were no significant differences between the two groups in heart rate, diastolic blood pressure (BP), systolic BP, and mean arterial pressure before, during, and after surgery (P > 0.05). There was no significant difference in blood variables before and after surgery (P > 0.05) except the platelet count that was in the normal range in both groups after surgery (P = 0.022). The mean volume of blood transfused in the case group was significantly lower than the control group during surgery (P = 0.008) and 12 h after surgery (P = 0.01).

Conclusion:

The prophylactic administration of TXA results in a significant reduction in need for blood transfusion and the duration of surgery. Given the lower risks of using TXA compared to the other drugs, it is recommended in hysterectomy to control bleeding.

MultiPep: a hierarchical deep learning approach for multi-label classification of peptide bioactivities

Peptide-based therapeutics are here to stay and will prosper in the future. A key step in identifying novel peptide-drugs is the determination of their bioactivities. Recent advances in peptidomics screening approaches hold promise as a strategy for identifying novel drug targets. However, these screenings typically generate an immense number of peptides and tools for ranking these peptides prior to planning functional studies are warranted. Whereas a couple of tools in the literature predict multiple classes, these are constructed using multiple binary classifiers. We here aimed to use an innovative deep learning approach to generate an improved peptide bioactivity classifier with capacity of distinguishing between multiple classes. We present MultiPep: a deep learning multi-label classifier that assigns peptides to zero or more of 20 bioactivity classes. We train and test MultiPep on data from several publically available databases. The same data are used for a hierarchical clustering, whose dendrogram shapes the architecture of MultiPep. We test a new loss function that combines a customized version of Matthews correlation coefficient with binary cross entropy (BCE), and show that this is better than using class-weighted BCE as loss function. Further, we show that MultiPep surpasses state-of-the-art peptide bioactivity classifiers and that it predicts known and novel bioactivities of FDA-approved therapeutic peptides. In conclusion, we present innovative machine learning techniques used to produce a peptide prediction tool to aid peptide-based therapy development and hypothesis generation.

Efficacy and safety of tranexamic acid in aneurysmal subarachnoid hemorrhage: A meta-analysis of randomized controlled trials

INTRODUCTION

Tranexamic acid, as a traditional hemostatic agent, is commonly used to treat or prevent excessive blood loss. However, the role of tranexamic acid in promoting good clinical outcomes and reducing mortality and risk of adverse events during the treatment of aneurysmal subarachnoid hemorrhage remains unclear.

METHODS

In strict accordance with the inclusion and exclusion criteria, Cochrane Library, Embase, Web of Science, and PubMed databases were assessed for randomized controlled trials (published between 1980 and 2021). Data were analyzed using STATA 16.0 and RevMan 5.3. In addition, the fixed-effects model (M-H method) and effect size (risk difference; RD) were used as a pooled measure to combine data. We also performed a post hoc sensitivity analysis and subgroup analysis to evaluate each outcome with low heterogeneity.

RESULTS

A meta-analysis revealed that although tranexamic acid was related to less rebleeding (RD = -0.06; 95% CI [-0.09, -0.03]; P = 0.0006), there is evidence that it has no an effect on good clinical outcomes or mortality (RD = -0.01; 95% CI [-0.05, 0.02]; P = 0.51; RD = 0.00; 95% CI [-0.03, 0.04]; P = 0.91). Tranexamic acid was associated with increased hydrocephalus (RD = 0.04; 95% CI [0.01, 0.08]; P = 0.02) and seizure (RD = 0.04; 95% CI [0.00, 0.08]; P = 0.05). The incidence of thromboembolic complications or delayed cerebral ischemia was not different in the two groups (RD = -0.01; 95% CI [-0.04, 0.03]; P = 0.62; RD = 0.00; 95% CI [-0.03, 0.03]; P = 0.96), and significant drug-related overall adverse events were identified (RD = 0.02; 95% CI [0.00, 0.04]; P = 0.03).

CONCLUSIONS

These findings indicate that the routine use of tranexamic acid is not suggested for patients with aneurysmal subarachnoid hemorrhage.

The Role of the C-Terminal Lysine of S100P in S100P-Induced Cell Migration and Metastasis

S100P protein is a potent inducer of metastasis in a model system, and its presence in cancer cells of patients is strongly associated with their reduced survival times. A well-established Furth Wistar rat metastasis model system, methods for measuring cell migration, and specific inhibitors were used to study pathways of motility-driven metastasis. Cells expressing C-terminal mutant S100P proteins display markedly-reduced S100P-driven metastasis in vivo and cell migration in vitro. These cells fail to display the low focal adhesion numbers observed in cells expressing wild-type S100P, and the mutant S100P proteins exhibit reduced biochemical interaction with non-muscle myosin heavy chain isoform IIA in vitro. Extracellular inhibitors of the S100P-dependent plasminogen activation pathway reduce, but only in part, wild-type S100P-dependent cell migration; they are without effect on S100P-negative cells or cells expressing C-terminal mutant S100P proteins and have no effect on the numbers of focal adhesions. Recombinant wild-type S100P protein, added extracellularly to S100P-negative cells, stimulates cell migration, which is abolished by these inhibitors. The results identify at least two S100P-dependent pathways of migration, one cell surface and the other intracellularly-linked, and identify its C-terminal lysine as a target for inhibiting multiple migration-promoting activities of S100P protein and S100P-driven metastasis.

Intraoperative Cell Saving: Is the Solution the Actual Problem?

Allogenic blood is a scarce, precious, and expensive resource that is not always available on demand. After termination of cardiopulmonary bypass, a large amount of residual pump blood remains in the extracorporeal circuit. The cell saver washes and concentrates this blood with .9% normal saline (NS), making autologous blood available and reducing the demand for allogenic blood. To quantify the quality of residual pump blood it was washed with either NS or a bicarbonate-buffered solution (Balsol). A qualitative in vitro analysis was conducted. Residual cardiopulmonary bypass blood from forty bypass circuits was processed with a cell saver device, using NS or Balsol solution. Measurements made compared the pH, electrolytes, metabolites, hematocrit, hemoglobin, osmolality, albumin, total protein, and strong ion difference. There were significant differences between the NS and Balsol groups. In the Balsol group, osmolality, electrolytes, and strong ion difference were similar to the constitution of Balsol solution after washing, but not with the normal saline group. Washing residual cardiopulmonary bypass pump blood with Balsol solution results in a resuspended red cell concentrate with a superior electrolyte profile and a strong ion difference similar to that of residual pump blood.

Intestinal differentiation involves cleavage of histone H3 N-terminal tails by multiple proteases

The proteolytic cleavage of histone tails, also termed histone clipping, has been described as a mechanism for permanent removal of post-translational modifications (PTMs) from histone proteins. Such activity has been ascribed to ensure regulatory function in key cellular processes such as differentiation, senescence and transcriptional control, for which different histone-specific proteases have been described. However, all these studies were exclusively performed using cell lines cultured in vitro and no clear evidence that histone clipping is regulated in vivo has been reported. Here we show that histone H3 N-terminal tails undergo extensive cleavage in the differentiated cells of the villi in mouse intestinal epithelium. Combining biochemical methods, 3D organoid cultures and in vivo approaches, we demonstrate that intestinal H3 clipping is the result of multiple proteolytic activities. We identified Trypsins and Cathepsin L as specific H3 tail proteases active in small intestinal differentiated cells and showed that their proteolytic activity is differentially affected by the PTM pattern of histone H3 tails. Together, our findings provide in vivo evidence of H3 tail proteolysis in mammalian tissues, directly linking H3 clipping to cell differentiation.

Six-Dose Intravenous Tranexamic Acid Regimen Further Inhibits Postoperative Fibrinolysis and Reduces Hidden Blood Loss following Total Knee Arthroplasty

There is no consensus regarding the ideal dosages and times of multiple-dose intravenous tranexamic acid (IV-TXA) administration in total knee arthroplasty (TKA). This study aimed to assess the effect of six-dose IV-TXA with the total dosage more than 6 g on postoperative fibrinolysis and hidden blood loss (HBL) after primary TKA. A total of 175 patients were randomized into three groups to receive placebo (group A), or a single preoperative dose of 20 mg/kg IV-TXA (group B), or six-dose IV-TXA from the beginning of the procedure to subsequent 24 hours with the total dosage more than 6 g (group C). The calculated HBL, maximum hemoglobin (Hb) drop, transfusion rate, and the incidence of thromboembolic events were compared among groups. The levels of fibrinolysis parameters in plasma including fibrin(-ogen) degradation products (FDP) and D-dimer were measured at six time points from preoperatively to 3-month postoperative period. The mean HBL and maximum Hb drop in group C (515.51 ± 245.79 mL, and 2.06 ± 0.73 g/dL, respectively) were significantly lower than those in groups B (756.06 ± 226.79 mL, p < 0.001; and 2.77 ± 0.78 g/dL, p < 0.001, respectively) and A (987.65 ± 275.38 mL, p < 0.001; and 3.49 ± 0.86 g/dL, p < 0.001, respectively). Such differences were also detected between groups A and B (p < 0.001 and p < 0.001, respectively). The levels of FDP and D-dimer in plasma were lower in group C than those in groups B and A on postoperative 24, 48, 72 hours (p < 0.001 for all). No episode of transfusion occurred, and the incidence of thromboembolic events were similar among groups (p > 0.05). The administration of six-dose IV-TXA during the first 24 hours resulted in reduced HBL following TKA without a measured increase in thromboembolic events.

Postoperative administration of tranexamic acid as approach to reduce blood loss after open-heart surgery

BACKGROUND: Tranexamic acid (TXA) reduces perioperative bleeding among patients undergoing heart surgery. It is uncertain whether its postoperative administration, after prior administration before cardiopulmonary bypass (CPB), has an additional benefit. OBJECTIVE: Our study aimed to evaluate whether the postoperative administration of TXA reduces the blood loss after heart surgery. METHODS: In a retrospective cohort study at the University Heart Center Dresden, patients who underwent on-pump open-heart surgery and received 1 g TXA before CPB were included. Patients with postoperative administration of 1 g TXA were compared to patients without. Primary endpoint was the postoperative blood loss within 24 hours. RESULTS: Among 2,179 patients undergoing heart surgery between 1 July 2013 and 31 October 2014, 92 (4.2%) received TXA postoperatively. After matching, 71 patients with postoperative administration of TXA were compared to 71 without (n = 142). Postoperative administration of TXA did not result in decreased blood loss (MD 146.7 mL; p = 0.064). There was no evidence of an increased risk for thromboembolic complications. CONCLUSIONS: The postoperative administration of TXA did not reduce blood loss. The use of TXA was shown to be safe in terms of thromboembolic events and hospital mortality. Unless there is no clear evidence, the postoperative administration of TXA should be restricted to patients with massive blood loss and signs of hyperfibrinolysis only.

[Research progress on tranexamic acid in traumatic orthopedic surgery]

OBJECTIVE

To summarize the research progress on the application of tranexamic acid (TXA) in traumatic orthopedic surgery in recent years.

METHODS

The domestic and foreign literature in recent years was reviewed, and the efficacy and safety of TXA in traumatic orthopedic surgeries with different regimen, dose and route of administration were comprehensively summarized and compared.

RESULTS

The application of TXA in traumatic orthopedic surgeries increased gradually in recent years. Intravenous or topical administration of TXA efficaciously reduced blood loss and transfusion requirements during hip fracture surgery without significantly increasing the risk of thromboembolic events. However, the efficacy was not clear in other traumatic orthopedic surgeries such as pelvic and acetabular fractures.

CONCLUSION

More studies are needed to confirm the efficacy and safety of TXA in traumatic orthopedic surgeries.

Animal-derived medicinal products in Russia: Current nomenclature and specific aspects of quality control

ETHNOPHARMACOLOGICAL RELEVANCE

Animal-derived medicinal products (ADMP) had been extensively used in Russia and became a part of officinal medicine in 1778.

AIM OF THE STUDY

The aim of the current review was to analyse the ADMPs authorised in the Russian Federation and to identify specific aspects of quality evaluation of these medicinal products.

MATERIALS AND METHODS

Information of ADMPs was extracted from the online State Register of Medicinal Products of the Russian Federation. At the next stage, we systematically searched library catalogues, E-library.ru, Medline/PubMed, Scopus, Web of Science and Google Scholar databases to find data related to ADMP quality evaluation, clinically proven efficacy and safety.

RESULTS

For classification of ADMP, we propose an approach based on the raw material used: ADMPs derived from marine organisms, ADMPs from cattle and pigs and ADMPs from other terrestrial animals. The majority of ADMPs authorised in Russia are produced by local manufacturers. ADMPs are available in dosage forms of solution for parenteral administration (35% of all products) and lyophilisates for parenteral use (19%), tablets and capsules (17% and 11%, respectively), ointments (5%) and powders (3%). ADMPs belong to the following pharmacotherapeutic groups: medicines for tissue regeneration and repair stimulators (30%), digestive enzyme products (22%), anticoagulants (17%), proteolytic agents (6%) and medicines for the treatment of chronic prostatitis (5%). The most important approaches to standardisation of ADMPs are implementation of modern requirements for registration dossiers, development of risk-oriented approaches for evaluation of impurities, elaboration of advanced instrumental and in vitro test methods capable of replacing in vivo methods and harmonisation of the potency units used for standardisation.

CONCLUSIONS

The key features of ADMPs that help them retain their leading position in the pharmaceutical market are as follows: (i) their unique composition usually represented by a complex of biologically active substances; (ii) a high degree of affinity of the active ingredient of an ADMP to the human body and (iii) proved safety and clinical efficiency. Variability in the quality of raw ingredients, epidemiological situation and other conditions pose additional challenges for the development of ADMPs and for the standardisation.

Is intravenous tranexamic acid effective and safe during hip fracture surgery? An updated meta-analysis of randomized controlled trials

INTRODUCTION

The efficacy and safety of intravenous (IV) tranexamic acid (TXA) during hip fracture surgery remain controversial. This meta-analysis aimed to assess the efficacy of IV-TXA administration during hip fracture surgery for reducing the transfusion requirement and blood loss as well as its safety regarding the risk of thrombolysis.

MATERIALS AND METHODS

PubMed, EMBASE, Web of Science, and the Cochrane Library Database were systematically searched for randomized controlled trials (RCTs) that focused on the efficacy and safety of IV-TXA in patients during hip fracture surgery. The primary outcome was the transfusion requirement. Secondary outcomes included total blood loss (TBL), deep vein thrombosis (DVT), and total thromboembolic events (TTEs). Risk ratio (RR), risk difference (RD), and mean difference (MD) for dichotomous and continuous data outcomes were determined from the meta-analysis. Data were analyzed using Rev Man 5.3.

RESULTS

Altogether, 11 RCTs were included (total sample size 892 patients). IV-TXA significantly reduced the transfusion requirement [RR 0.60, 95% confidence interval (CI) 0.38-0.93, P = 0.02] and TBL (MD 326.64 ml, 95% CI - 462.23 to - 191.06, P < 0.00001) vs. cosntrol group. IV-TXA caused no increased risk of DVT (RD 0.02, 95% CI - 0.01 to 0.04, P = 0.13) or TTEs (RD 0.02, 95% CI - 0.01 to 0.05, P = 0.12).

CONCLUSION

Available evidence indicates that IV-TXA efficaciously reduces TBL and transfusion requirements during hip fracture surgery without significantly increasing the risk of TTEs including DVT.

Hemostatic Agents in Critically Ill Patients

How to cite this article: Das SK, Reddy MM, Ray S. Hemostatic Agents in Critically Ill Patients. Indian J Crit Care Med 2019;23(Suppl 3):S226–S229.

Tranexamic acid administration to older patients undergoing primary total hip arthroplasty conserves hemoglobin and reduces blood loss

BACKGROUND

Tranexamic acid effects in older people are difficult to predict. This study investigated the following research questions: 1) Is tranexamic acid effective in older patients undergoing primary total hip arthroplasty (THA)? and 2) Is there a difference in the effect of tranexamic acid between younger and older patients?

METHODS

This was a 2-phase retrospective matched-pair study of patients who underwent THA in 2007-2013. All procedures were performed by surgeons with at least 10 years' experience as senior consultant. In the first phase, 58 patients aged 65 years or more who received tranexamic acid were matched 1:1 with patients who did not receive tranexamic acid for age, sex, American Society of Anesthesiologists (ASA) classification and body mass index. In the second phase, 58 patients aged 65 years or more who received tranexamic acid were matched 1:1 with patients less than 65 years of age who received tranexamic acid for sex, ASA classification and body mass index. The primary outcome measures were percent maximum decrease in hemoglobin level and estimated blood loss after surgery.

RESULTS

In the first phase, patients who received tranexamic acid conserved postoperative hemoglobin by a mean of 10.26 g/L (standard deviation [SD] 9.89 g/L) compared to the control group (p < 0.001). The mean difference in the estimated perioperative blood loss between the 2 groups was 410 mL (SD 376 mL) (p < 0.001), which indicated less bleeding in the treatment group. In the second phase, there was no difference between the younger (mean age 55.1 [SD 7.28] yr) and older (mean age 75.6 [SD 6.35] yr) groups in mean lowest postoperative hemoglobin level or percent decrease in hemoglobin level.

CONCLUSION

Tranexamic acid reduced the postoperative decrease in hemoglobin level and blood loss in older patients. Moreover, the significant hemoglobin-sparing effect of tranexamic acid in older patients was similar to that observed in younger patients.

Optimizing Blended Collagen-Fibrin Hydrogels for Cardiac Tissue Engineering with Human iPSC-derived Cardiomyocytes

Natural polymer hydrogels are used ubiquitously as scaffold materials for cardiac tissue engineering as well as for soft tissue engineering more broadly because of FDA approval, minimal immunogenicity, and well-defined physiological clearance pathways. However, the relationships between natural polymer hydrogels and resident cell populations in directing the development of engineered tissues are poorly defined. This interaction is of particular concern for tissues prepared with iPSC-derived cell populations, in which population purity and batch-to-batch variability become additional critical factors to consider. Herein, the design space for a blended fibrin and collagen scaffold is characterized for applications in creating engineered myocardium with human iPSC-derived cardiomyocytes. Stiffness values of the acellular hydrogel formulations approach those of native myocardium in compression, but deviate significantly in tension when compared to rat myocardium in both transverse and longitudinal fiber orientations. A response surface methodology approach to understanding the relationship between collagen concentration, fibrin concentration, seeding density, and cardiac purity found a statistically significant predictive model across three repeated studies that confirms that all of these factors contribute to tissue compaction. In these constructs, increased fibrin concentration and seeding density were each associated with increased compaction, while increased collagen concentration was associated with decreased compaction. Both the lowest (24.4% cTnT⁺) and highest (60.2% cTnT⁺) cardiomyocyte purities evaluated were associated with decreased compaction, whereas the greatest compaction was predicted to occur in constructs prepared with a 40–50% cTnT⁺ population. Constructs prepared with purified cardiomyocytes (≥75.5% cTnT⁺) compacted and formed syncytia well, although increased fibrin concentration in these groups was associated with decreased compaction, a reversal of the trend observed in unpurified cardiomyocytes. This study demonstrates an analytical approach to understanding cell–scaffold interactions in engineered tissues and provides a foundation for the development of more sophisticated and customized scaffold platforms for human cardiac tissue engineering.

Carbon Nanotube Strain Sensor Based Hemoretractometer for Blood Coagulation Testing

Coagulation monitoring is essential for perioperative care and thrombosis treatment. However, existing assays for coagulation monitoring have limitations such as a large footprint and complex setup. In this work, we developed a miniaturized device for point-of-care blood coagulation testing by measuring dynamic clot retraction force development during blood clotting. In this device, a blood drop was localized between a protrusion and a flexible force-sensing beam to measure clot retraction force. The beam was featured with micropillar arrays to assist the deposition of carbon nanotube films, which served as a strain sensor to achieve label-free electrical readout of clot retraction force in real time. We characterized mechanical and electrical properties of the force-sensing beam and optimized its design. We further demonstrated that this blood coagulation monitoring device could obtain results that were consistent with those using an imaging method and that the device was capable of differentiating blood samples with different coagulation profiles. Owing to its low fabrication cost, small size, and low consumption of blood samples, the blood coagulation testing device using carbon nanotube strain sensors holds great potential as a point-of-care tool for future coagulation monitoring.

Effectiveness and safety of an optimized blood management program in total hip and knee arthroplasty: A large, single-center, retrospective study

Little has been published on blood management in total hip and knee arthroplasty (THA and TKA, respectively) patients focusing on both hematopoiesis and hemostasis. Our aim was to explore the effectiveness and safety of an optimized blood management program in THA and TKA patients in a large, single-center, retrospective study.We retrospectively reviewed consecutive primary unilateral THA and TKA patients' data at our institution through the National Health Database. They were divided into 3 groups according to an optimized blood management program: group A-combined use of intravenous and topical tranexamic acid (TXA); group B-use of recombinant human erythropoietin (rHuEPO) and iron supplements in addition to treatments in group A; group C-use of additional multiple boluses of TXA in addition to treatments in group B. The primary outcomes were hemoglobin (Hb) drop and calculated total blood loss (TBL). Other outcome measurements such as transfusion rate, postoperative length of stay (PLOS), venous thromboembolism (VTE), and mortality were also compared.From 2014 to 2016, a total of 1907 unilateral THA (986 in group A, 745 in group B, and 176 in group C) and 1505 unilateral TKA (795 in group A, 556 in group B, and 154 in group C) procedures were conducted at our institution. The Hb drop, calculated TBL, and PLOS in group C were significantly lower than those in groups A and B for THA and TKA patients. The transfusion rate in group C was also significantly less than in groups A and B for THA patients, while it was similar in groups A and B for TKA patients. No patients in group C received a transfusion. A significant difference was not detected in the incidence of deep vein thrombosis. No episode of symptomatic pulmonary embolism or all-cause mortality occurred within 30 days postoperatively.The current retrospective study suggests that for patients receiving primary unilateral THA or TKA, multiple boluses of intravenous TXA combined with topical TXA, rHuEPO, and iron supplements can reduce the calculated TBL, Hb drop, transfusion rate, and PLOS without increasing the incidence of VTE or mortality.

Pretreatment of a matrix metalloproteases inhibitor and aprotinin attenuated the development of acute pancreatitis-induced lung injury in rat model

OBJECTIVE

Acute lung injury (ALI) is one of the most common extra-pancreatic complications of acute pancreatitis. In this study, we examined the protective effect of protease inhibitor aprotinin and a matrix metalloproteinase inhibitor (MMPi) on pulmonary inflammation in rats with severe pancreatitis-associated ALI.

METHOD

A rat model of acute pancreatitis (AP) was established by injecting sodium glycodeoxycholate (GDOC) into the pancreatic duct. Pharmacological interventions included pretreatment with a protease inhibitor aprotinin (10mg/kg) and a matrix metalloproteinase inhibitor (MMPi, 100g/kg). The extent of pancreatic and lung injury and systemic inflammation was assessed by examinations of blood, bronchoalveolar lavage (BAL), and lung tissue. Pancreatic or lung tissue edema was evaluated by tissue water content. Pulmonary arterial pressure and alveolar-capillary membrane permeability were evaluated post-injury via a catheter inserted into the pulmonary artery in an isolated, perfused lung model.

RESULTS

Pre-treatment with aprotinin or MMPi significantly decreased amylase and lactate dehydrogenase (LDH), and the wet/dry weight ratio of the lung and pancreas in AP rats. Compared to the GDOC alone group, administration of aprotinin or MMPi prevented pancreatitis-induced IL-6 increases in the lung. Similarly, treatment with aprotinin or MMPi significantly decreased the accumulation of white blood cells, oxygen radicals, nitrite/nitrates in both blood and BAL, and markedly reduced lung permeability.

CONCLUSION

Pretreatment with either aprotinin or MMPi attenuated the systemic inflammation and reduced the severity of lung and pancreas injuries. In short, our study demonstrated that inhibition of protease may be therapeutic to pulmonary inflammation in this GDOC-induced AP model.

Activation of tissue plasminogen activator by metastasis-inducing S100P protein

S100P protein in human breast cancer cells is associated with reduced patient survival and, in a model system of metastasis, it confers a metastatic phenotype upon benign mammary tumour cells. S100P protein possesses a C-terminal lysine residue. Using a multiwell in vitro assay, S100P is now shown for the first time to exhibit a strong, C-terminal lysine-dependent activation of tissue plasminogen activator (tPA), but not of urokinase-catalysed plasminogen activation. The presence of 10 μM calcium ions stimulates tPA activation of plasminogen 2-fold in an S100P-dependent manner. S100P physically interacts with both plasminogen and tPA in vitro, but not with urokinase. Cells constitutively expressing S100P exhibit detectable S100P protein on the cell surface, and S100P-containing cells show enhanced activation of plasminogen compared with S100P-negative control cells. S100P shows C-terminal lysine-dependent enhancement of cell invasion. An S100P antibody, when added to the culture medium, reduced the rate of invasion of wild-type S100P-expressing cells, but not of cells expressing mutant S100P proteins lacking the C-terminal lysine, suggesting that S100P functions outside the cell. The protease inhibitors, aprotinin or α-2-antiplasmin, reduced the invasion of S100P-expressing cells, but not of S100P-negative control cells, nor cells expressing S100P protein lacking the C-terminal lysine. It is proposed that activation of tPA via the C-terminal lysine of S100P contributes to the enhancement of cell invasion by S100P and thus potentially to its metastasis-promoting activity.

Human Kunitz-type protease inhibitor engineered for enhanced matrix retention extends longevity of fibrin biomaterials

Aprotinin is a broad-spectrum serine protease inhibitor used in the clinic as an anti-fibrinolytic agent in fibrin-based tissue sealants. However, upon re-exposure, some patients suffer from hypersensitivity immune reactions likely related to the bovine origin of aprotinin. Here, we aimed to develop a human-derived substitute to aprotinin. Based on sequence homology analyses, we identified the Kunitz-type protease inhibitor (KPI) domain of human amyloid-β A4 precursor protein as being a potential candidate. While KPI has a lower intrinsic anti-fibrinolytic activity than aprotinin, we reasoned that its efficacy is additionally limited by its fast release from fibrin material, just as aprotinin's is. Thus, we engineered KPI variants for controlled retention in fibrin biomaterials, using either covalent binding through incorporation of a substrate for the coagulation transglutaminase Factor XIIIa or through engineering of extracellular matrix protein super-affinity domains for sequestration into fibrin. We showed that both engineered KPI variants significantly slowed plasmin-mediated fibrinolysis in vitro, outperforming aprotinin. In vivo, our best engineered KPI variant (incorporating the transglutaminase substrate) extended fibrin matrix longevity by 50%, at a dose at which aprotinin did not show efficacy, thus qualifying it as a competitive substitute of aprotinin in fibrin sealants.

Use of an absorbable embolization material for reversible portal vein embolization in an experimental model

BACKGROUND

Portal vein embolization (PVE) is used to increase future remnant liver size in patients requiring major hepatic resection. PVE using permanent embolization, however, predisposes to complications and excludes the use of PVE in living donor liver transplantation. In the present study, an absorbable embolization material containing fibrin glue and different concentrations of the fibrinolysis inhibitor aprotinin was used in an experimental animal model.

METHODS

PVE of the cranial liver lobes was performed in 30 New Zealand White rabbits, which were divided into five groups, fibrin glue + 1000, 700, 500, 300 or 150 kunits/ml aprotinin, and were compared with a previous series of permanent embolization using the same experimental set-up. Caudal liver lobe hypertrophy was determined by CT volumetry, and portal recanalization was identified on contrast-enhanced CT images. Animals were killed after 7 or 42 days, and the results were compared with those of permanent embolization.

RESULTS

PVE using fibrin glue with aprotinin as embolic material was effective, with 500 kunits/ml providing the optimal hypertrophic response. Lower concentrations of aprotinin (150 and 300 kunits/ml) led to reduced hypertrophy owing to early recanalization of the embolized segments. The regeneration rate over the first 3 days was higher in the group with 500 kunits/ml aprotinin than in the groups with 300 or 150 kunits/ml or permanent embolization. In the 500-kunits/ml group, four of five animals showed recanalization 42 days after embolization, with minimal histological changes in the cranial lobes following recanalization.

CONCLUSION

Fibrin glue combined with 500 kunits/ml aprotinin resulted in reversible PVE in 80 per cent of animals, with a hypertrophy response comparable to that achieved with permanent embolization material. Surgical relevance Portal vein embolization (PVE) is used to increase future remnant liver volume in patients scheduled for major liver resection who have insufficient future remnant liver size to perform a safe resection. The current standard is PVE with permanent embolization materials, which renders patients found to have unresectable disease prone to complications owing to the permanently deportalized liver segments. Absorbable embolization might prevent the PVE-associated morbidity and lower the threshold for its application. In this study, PVE using fibrin glue and aprotinin resulted in an adequate hypertrophy response with 80 per cent recanalization after 42 days. Considering the minor histological changes following recanalization of embolized segments and potentially preserved function, reversible PVE might also be applied in living donor liver transplantation.

Introducing DInaMo: A Package for Calculating Protein Circular Dichroism Using Classical Electromagnetic Theory

The dipole interaction model is a classical electromagnetic theory for calculating circular dichroism (CD) resulting from the π-π* transitions of amides. The theoretical model, pioneered by J. Applequist, is assembled into a package, DInaMo, written in Fortran allowing for treatment of proteins. DInaMo reads Protein Data Bank formatted files of structures generated by molecular mechanics or reconstructed secondary structures. Crystal structures cannot be used directly with DInaMo; they either need to be rebuilt with idealized bond angles and lengths, or they need to be energy minimized to adjust bond lengths and bond angles because it is common for crystal structure geometries to have slightly short bond lengths, and DInaMo is sensitive to this. DInaMo reduces all the amide chromophores to points with anisotropic polarizability and all nonchromophoric aliphatic atoms including hydrogens to points with isotropic polarizability; all other atoms are ignored. By determining the interactions among the chromophoric and nonchromophoric parts of the molecule using empirically derived polarizabilities, the rotational and dipole strengths are determined leading to the calculation of CD. Furthermore, ignoring hydrogens bound to methyl groups is initially explored and proves to be a good approximation. Theoretical calculations on 24 proteins agree with experiment showing bands with similar morphology and maxima.

The prophylactic role of tranexamic acid to reduce blood loss during radical surgery: A prospective study

BACKGROUND

The radical surgical procedures are associated with perioperative blood loss. This study was aimed to evaluate the clinical efficacy and safety of tranexamic acid in reducing perioperative blood loss in patients undergoing radical surgery.

MATERIALS AND METHODS

Sixty ASA class I and II adult consented female patients, scheduled for elective radical surgery and met the inclusion criterion, were blindly randomized into two groups to receive either intravenous 1 g tranexamic acid 20 min before skin incision or an equivalent volume of normal saline as placebo (P). All patient's total blood loss was measured and recorded perioperatively at the 12(th)h postoperatively. The preoperative and postoperative hemoglobin, hematocrit values, serum creatinine, activated thromboplastin time, prothombin time, thrombocyte count, fibrinogen, D-dimer, and symptoms of pulmonary embolism were comparatively evaluated.

RESULTS

The tranexamic acid significantly reduced the quantity of total blood loss, 576 ± 53 mL in study group as compared to 823 ± 74 mL in the control group (P<0.01). Postoperatively hematocrit values were higher in the tranexamic acid group. The coagulation profile did not differ between the groups, but D-dimer concentrations were increased in the control group. No complications or adverse effects were reported in the either group.

CONCLUSION

The prophylactic administration of tranexamic acid has effectively reduced theblood loss and transfusion needs during radical surgery without any adverse effects or complication of thrombosis.

Does tranexamic acid alter the risk of thromboembolism after total hip arthroplasty in the absence of routine chemical thromboprophylaxis?

Tranexamic acid (TXA) has been used to reduce blood loss during total hip arthroplasty (THA), but its use could increase the risk of venous thromboembolic disease (VTE). Several studies have reported that TXA does not increase the prevalence of deep vein thrombosis (DVT), but most of those used routine chemical thromboprophylaxis, thereby masking the potential increased risk of TXA on VTE. We wished to ascertain whether TXA increases the prevalence of VTE in patients undergoing THA without routine chemical thromboprophylaxis. We carried out a retrospective case-control study in 254 patients who underwent a primary THA, 127 of whom received TXA (1 g given pre-operatively) and a control group of 127 who did not. All patients had mechanical but no chemical thomboprophylaxis. Each patient was examined for DVT by bilateral ultrasonography pre-operatively and on post-operative days 1 and 7. TXA was found to statistically significantly increase the incidence of total DVT on post-operative day 7 compared with the control group (24 (18.9%) and 12 (9.4%), respectively; p < 0.05) but most cases of DVT were isolated distal DVT, with the exception of one patient with proximal DVT in each group. One patient in the control group developed a non-fatal symptomatic pulmonary embolism (PE). The use of TXA did not appear to affect the prevalence of either proximal DVT or PE.

Cite this article: Bone Joint J 2015; 97-B:458–62.

Tranexamic acid – a useful drug in ENT surgery?

Background:

Tranexamic acid is a synthetic antifibrinolytic drug. It has been widely available for over 40 years, but only recently has it started to be used routinely in many surgical disciplines. For ENT surgeons, epistaxis and post-tonsillectomy bleeding contribute a significant proportion of the morbidity and emergency workload in a general ENT department. Published evidence indicates a potentially helpful role for tranexamic acid in managing epistaxis.

Results and conclusion:

To date, the benefits of tranexamic acid as a prophylactic treatment to reduce the rate and severity of post-tonsillectomy bleeding are less certain. Two recently published pilot studies looking at primary haemorrhage in children and secondary haemorrhage in adults following tonsillectomy suggest that further large, randomised trials should explore the efficacy of tranexamic acid in routine ENT surgery. There are potential reductions in patient morbidity and cost savings if tranexamic acid is found to be efficacious in larger trials.

Perioperative tranexamic acid in day-case paediatric tonsillectomy

INTRODUCTION

Tranexamic acid has been used for many years to minimise blood loss during surgery and, more recently, to reduce morbidity after major trauma. While small studies have confirmed reduction in blood loss during tonsillectomy with its use, the rate of primary haemorrhage following tonsillectomy has not been reported. In the UK, less than 50% of children having a tonsillectomy are managed as day cases, partly because of concerns about bleeding during the initial 24 hours following surgery.

METHODS

A retrospective review of clinical records between January 2007 and January 2013 produced 476 children between the ages of 3 and 16 years who underwent Coblation™ tonsillectomy, with or without adenoidectomy and/or insertion of ventilation tubes. All children were ASA (American Society of Anesthesiologists) grade 1 or 2 and anaesthetised using a standard day surgery protocol. Following induction of anaesthesia, all received intravenous tranexamic acid at a dose of 10-15 mg/kg.

RESULTS

Two children (0.4%) had minor bleeding within two hours of surgery. Both returned to theatre for haemostasis and were discharged home later the same day with no further complications. The expected rate for primary haemorrhage in the UK using this technique for tonsillectomy is 1%.

CONCLUSIONS

Perioperative tranexamic acid in a single, parenteral dose might reduce the incidence of primary haemorrhage following paediatric tonsillectomy, facilitating discharge on the day of surgery. The results from this observational study indicate a potential benefit and need for a large, prospective, multicentre, randomised controlled trial.

Bronchoscopic intratumoral injection of tranexamic acid to prevent excessive bleeding during multiple forceps biopsies of lesions with a high risk of bleeding: a prospective case series

BACKGROUND

Significant bleeding may occur following endobronchial forceps biopsy or brushing of necrotic or hypervascular tumors in the airways. In some cases, methods such as endobronchial instillation of iced saline lavage and epinephrine may fail to control bleeding. The present study evaluated the efficacy and safety of a new bronchoscopic technique using intratumoral injection of tranexamic acid (IIT) for control of bleeding during forceps biopsy in patients with endobronchial tumors with a high risk of bleeding.

METHODS

The study was a prospective case series carried out in a single center. Bronchoscopic IIT was performed in those patients who had endoscopically visible tumoral lesions with persistent active bleeding following the first attempt at bronchoscopic sampling. Tranexamic acid (TEA) was injected through a 22-gauge Wang cytology needle into the lesion in nominal doses of 250-500 mg. After 2-3 minutes, multiple forceps biopsy specimens were obtained from the lesion.

RESULTS

Of the 57 consecutive patients included in the study, 20 patients (35.1%) underwent bronchoscopic IIT. The first attempt in 18 patients was endobronchial forceps biopsy (EBB), and because of a high risk of bleeding, the first attempt for the remaining two patients, who were on continuous dual antiplatelet therapy (aspirin and clopidogrel), employed endobronchial needle aspiration (EBNA) as a precautionary measure. Following IIT, subsequent specimens were obtained using EBB in all patients. Multiple forceps biopsy specimens (3-10) were obtained from the lesions (8 necrotic and 12 hypervascular) without incurring active bleeding. The following histopathologic diagnoses were made: squamous cell carcinoma (n = 14), adenocarcinoma (n = 2), small-cell lung cancer (n = 3), and malignant mesenchymal tumor (n = 1). No side effects of TEA were observed.

CONCLUSIONS

Bronchoscopic IIT is a useful and safe technique for controlling significant bleeding from a forceps biopsy procedure and can be considered as a pre-biopsy injection for lesions with a high risk of bleeding.

TRIAL REGISTRATION

ISRCTN23323895.

Spinal surgery in the univentricular heart--is it viable?

INTRODUCTION

The management of patients with Fontan physiology who undergo scoliosis surgery is difficult. The purpose of this article was to describe our experience in the management of patients with Fontan circulation undergoing spinal surgery for correction of scoliosis.

MATERIALS AND METHODS

This was a retrospective study including patients with Fontan physiology who underwent spinal orthopaedic surgery. Anaesthetic management, post-operative complications, paediatric intensive care unit and total hospital stay, and the need for blood transfusions were analysed.

RESULTS

We identified eight children with Fontan physiology who had undergone spinal surgery from 2000 to 2010. All patients were receiving cardiac medications at the time of spinal surgery. The mean age at surgery was 14.8 years (range 12-21). In all, three patients needed inotropic support with dopamine (3, 5, and 8 μg/kg/min), which was started during surgery. During the immediate post-operative period, one patient died because of hypovolaemic shock caused by massive bleeding and dysrythmia. Mean blood loss during the post-operative period was 22.2 cc/kg (7.8-44.6). Surgical drainages were maintained for a mean time of 3 days (range 1-7). The mean hospital stay was 9.2 days (range 6-19). Pleural effusions developed in two patients. On follow-up, one patient presented with thoracic pseudarthrosis and another with a serohaematoma of the surgical wound.

CONCLUSIONS

Spinal surgery in patients with Fontan circulation is a high-risk operation. These patients must be managed by a specialised team.

Aprotinin in cardiac surgery

Aprotinin is a naturally occurring serine protease inhibitor that is being used with increasing frequency in cardiac surgery and beyond to reduce blood loss and the need for perioperative blood transfusion. Through inhibition of serine proteases such as plasmin, aprotinin significantly reduces fibrinolysis, thereby aiding hemostasis during surgical procedures. In addition, aprotinin interacts with other factors in the coagulation and fibrinolytic cascade, creating a hemostatic balance, without increasing the risk of thrombosis. These proven benefits are supplemented by the anti-inflammatory properties of aprotinin, which may help curb some of the deleterious effects of cardiopulmonary bypass. This article will review the discovery of aprotinin, its mechanism of action, dosing and adverse effects, and highlight the major recent trials demonstrating its efficacy.

Safety of surgical treatment for patients with scoliosis and surgically corrected congenital cardiac malformations: a comparison with patients with scoliosis and normal hearts

OBJECT

The safety of spinal fusion has been poorly studied in children with surgically corrected congenital cardiac malformations (CCMs). The objective of this study was to evaluate the safety of spinal fusion in patients with CCMs following cardiac surgery.

METHODS

A retrospective study was conducted on 32 patients with scoliosis who received surgical treatment for their CCMs (CCM group). Sixty-four age- and sex-matched patients with scoliosis and normal hearts who received spinal fusion served as the control group. These 2 groups were compared for demographic distribution, blood loss, transfusion requirements, and incidence of postoperative complications.

RESULTS

The ages, curve pattern distributions, and number of levels fused were similar between the 2 groups before spinal fusion. Overall, a total of 7 patients in the CCM group (21.9%) and 5 (7.8%) in the control group had documented postoperative complications. The perioperative allogenic blood transfusion rate and mean red blood cell transfusion requirement in the CCM group were significantly higher than those found in patients in the control group (68.7% vs 28.1%, respectively, p = 0.000; and 2.68 ± 2.76 units/patient vs 0.76 ± 1.07 units/patient, respectively, p = 0.011). In the CCM group, a preoperative major curve magnitude ≥ 80° was the most accurate indicator of an increased risk for a major complication (p = 0.019), whereas no statistically significant correlation was noted between postoperative complications and age, type of congenital heart disease, operative duration, and estimated blood loss during the operation and transfusion.

CONCLUSIONS

Spinal fusion subsequent to prior cardiac surgery is relatively safe and effective in correcting the spinal deformity for patients with scoliosis and surgically corrected CCMs. A preoperative major curve magnitude ≥ 80° may be a risk factor in predicting postoperative complications in scoliotic patients with surgically corrected CCMs.

Influence of tranexamic acid on postoperative autologous blood retransfusion in primary total hip and knee arthroplasty: a randomized controlled trial

BACKGROUND

Postoperatively shed blood salvage is commonly used to reduce allogenic blood transfusion in patients undergoing total hip (THA) and knee arthroplasty (TKA). Autologous blood retransfusion is not devoid of risk. We hypothesized that adding tranexamic acid (TXA) to a restrictive blood transfusion protocol would reduce the need for postoperative autologous blood retransfusion in primary knee and hip arthroplasty.

STUDY DESIGN AND METHODS

Ninety-eight adult patients undergoing primary THA or TKA were randomly assigned to receive an intraoperative intravenous loading dose of 1.0 g of TXA followed by another 1.0-g dose 3 hours later (TXA group) or a matching volume 0.9% saline placebo (control group). A postoperatively shed autologous blood recovery system was used in all patients and the minimum reinfusion volume set at 250 mL. Red blood cells were transfused if hemoglobin level was less than 8 or if 8 to 10 g/dL with symptoms of anemia.

RESULTS

The proportion of patients receiving autologous blood reinfusion was significantly lower in the TXA group (5/49) compared to placebo (42/49) with an absolute difference of -75.5% (adjusted relative risk, 0.005), and none of the patients in the TXA group received more than 400 mL retransfused. Median total external blood loss during the first 24 hours was lower in the TXA group, 320 mL (range, 80-930 mL), compared to 970 mL (range, 100-2600 mL) in the placebo group (p < 0.001). There were no significant differences in homologous blood transfusions and hematologic variables between groups. Treatment differences were consistent by size and significance when the analysis was repeated separately in patients undergoing TKA or THA.

CONCLUSION

Addition of TXA to a restrictive transfusion protocol makes the use of a postoperative blood salvage system in patients undergoing primary hip and knee arthroplasty unnecessary.

Comparison of aprotinin and tranexamic acid in adult scoliosis correction surgery

PURPOSE

A retrospective review of consecutive adult patients undergoing scoliosis correction surgery was performed to compare the effects of aprotinin and tranexamic acid in blood conservation and to define a comprehensive blood conservation strategy for such surgery.

METHODS

Medical records of all patients who underwent scoliosis correction surgery in this unit between January 2003 and December 2008 were reviewed. The patients were divided into three cohorts: group 1 receiving no antifibrinolytics, group 2 aprotinin and group 3 tranexamic acid. Information was collected regarding number of vertebral levels fused, pre- and post-operative haemoglobin, intra-operative blood loss and peri-operative autologous and allogenic blood transfusion performed.

RESULTS

Aprotinin was used in 28 patients (38%), tranexamic acid in 26 (36%), while 19 (26%) received no antifibrinolytics. 21 patients had anterior surgery, 34 patients had posterior surgery and 18 had combined anterior and posterior procedures. Mean blood loss in the patients who received aprotinin and tranexamic acid was 710 and 738 ml, respectively. This was significantly less than the patients receiving no antifibrinolytics (972 ml, p = 0.037). Blood transfusion was required in only two patients undergoing anterior correction surgery.

CONCLUSION

Aprotinin and tranexamic acid reduce blood loss in adult spinal deformity correction surgery. With aprotinin being unavailable for clinical use, we recommend the use of tranexamic acid along with other blood conservation measures for adult spinal deformity correction surgery.

Bronchoscopic intratumoral injection of tranexamic acid: a new technique for control of biopsy-induced bleeding

In order to achieve an optimal diagnostic yield in patients with endoscopically visible tumors multiple biopsies are needed. However, some centrally located necrotic endobronchial tumors and other vascular-appearing tumors are prone to bleed significantly after the first biopsy, which poses a distressed and complicated management problem for a bronchoscopist. In the present case study, a new technique, using intratumoral injection of tranexamic acid to control significant bleeding during bronchoscopic biopsy, is described. Although this study is limited to two cases, it has been suggested that good control of biopsy-induced bleeding can be attained using this technique.

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.