Plasma tranexamic acid concentrations during cardiopulmonary bypass

Point-of-care testing for tranexamic acid efficacy: a proof-of-concept study in cardiac surgical patients

BACKGROUND

Low-dose tranexamic acid (TXA) has been recently recommended for cardiopulmonary bypass (CPB) to reduce associated complications. Although point-of-care laboratory tests for TXA concentrations are unavailable, a novel TPA-test on the ClotPro® system can measure TXA-induced inhibition of fibrinolysis. We evaluated the performance of the TPA-test in vitro and in patients undergoing surgery requiring CPB.

METHODS

Blood samples were obtained from six volunteers for in vitro evaluation of tissue plasminogen activator (tPA)-triggered fibrinolysis and the effects of TXA. This was followed by an observational study in 20 cardiac surgery patients to assess clinical effects of TXA on the TPA-test.

RESULTS

Hyperfibrinolysis induced by tPA was inhibited by TXA ≥2 mg L-1 in a concentration-dependent manner, and was completely inhibited at TXA ≥10 mg L-1. In patients undergoing CPB, antifibrinolytic effect was detectable on TPA-test parameters after a 0.1 g bolus of TXA at the end of CPB, and complete inhibition of fibrinolysis was obtained with TXA ≥0.5 g. The antifibrinolytic effects of 1 g TXA on TPA-test parameters were gradually attenuated over 18 h after surgery. However, the fibrinolytic inhibition continued in four patients with estimated glomerular filtration rate (eGFR) ≤30 ml min-1 1.73 m-2. The eGFR had strong correlations with TPA-test parameters at 18 h after surgery (r=0.86-0.92; P<0.0001).

CONCLUSIONS

The TPA-test is sensitive to low concentrations of TXA and serves as a practical monitoring tool for postoperative fibrinolytic activity in cardiac surgery patients. This test might be particularly useful in patients with severe renal impairment.

Long Duration of Action of Tranexamic Acid After Cardiac Surgery in a Hemodialysis Patient: A Case Report

A 61-year-old woman with chronic renal dysfunction was scheduled to undergo aortic valve replacement. After a bolus of 1 g tranexamic acid (TXA), the TPA (tissue-plasminogen activator)-test result with the ClotPro system demonstrated extensive inhibition of fibrinolysis. Plasma TXA level decreased from 71 to 25 μg/dL at 6 hours postoperatively; however, no further decrease was observed. Although TXA levels dropped to 6.9 μg/dL after hemodialysis on postoperative day (PoD) 1, fibrinolytic shutdown on the TPA-test remained unchanged until PoD 2. In dialysis patients, low-dose TXA <1 g may be considered for reducing seizure and thromboembolic complications after cardiac surgery.

Update on Applications and Limitations of Perioperative Tranexamic Acid

Tranexamic acid (TXA) is a potent antifibrinolytic with documented efficacy in reducing blood loss and allogeneic red blood cell transfusion in several clinical settings. With a growing emphasis on patient blood management, TXA has become an integral aspect of perioperative blood conservation strategies. While clinical applications of TXA in the perioperative period are expanding, routine use in select clinical scenarios should be supported by evidence for efficacy. Furthermore, questions regarding optimal dosing without increased risk of adverse events such as thrombosis or seizures should be answered. Therefore, ongoing investigations into TXA utilization in cardiac surgery, obstetrics, acute trauma, orthopedic surgery, neurosurgery, pediatric surgery, and other perioperative settings continue. The aim of this review is to provide an update on the current applications and limitations of TXA use in the perioperative period.

Effect of High- vs Low-Dose Tranexamic Acid Infusion on Need for Red Blood Cell Transfusion and Adverse Events in Patients Undergoing Cardiac Surgery: The OPTIMAL Randomized Clinical Trial

IMPORTANCE

Tranexamic acid is recommended for reducing blood loss and transfusion in cardiac surgery. However, it remains unknown whether a high dose of tranexamic acid provides better blood-sparing effect than a low dose without increasing the risk of thrombotic complications or seizures in cardiac surgery.

OBJECTIVE

To compare the efficacy and adverse events of high-dose vs low-dose tranexamic acid in patients undergoing cardiac surgery with cardiopulmonary bypass.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter, double-blind, randomized clinical trial among adult patients undergoing cardiac surgery with cardiopulmonary bypass. The study enrolled 3079 patients at 4 hospitals in China from December 26, 2018, to April 21, 2021; final follow-up was on May 21, 2021.

INTERVENTIONS

Participants received either a high-dose tranexamic acid regimen comprising a 30-mg/kg bolus, a 16-mg/kg/h maintenance dose, and a 2-mg/kg prime (n = 1525) or a low-dose regimen comprising a 10-mg/kg bolus, a 2-mg/kg/h maintenance dose, and a 1-mg/kg prime (n = 1506).

MAIN OUTCOMES AND MEASURES

The primary efficacy end point was the rate of allogeneic red blood cell transfusion after start of operation (superiority hypothesis), and the primary safety end point was a composite of the 30-day postoperative rate of mortality, seizure, kidney dysfunction (stage 2 or 3 Kidney Disease: Improving Global Outcomes [KDIGO] criteria), and thrombotic events (myocardial infarction, ischemic stroke, deep vein thrombosis, and pulmonary embolism) (noninferiority hypothesis with a margin of 5%). There were 15 secondary end points, including the individual components of the primary safety end point.

RESULTS

Among 3079 patients who were randomized to treatment groups (mean age, 52.8 years; 38.1% women), 3031 (98.4%) completed the trial. Allogeneic red blood cell transfusion occurred in 333 of 1525 patients (21.8%) in the high-dose group and 391 of 1506 patients (26.0%) in the low-dose group (risk difference [RD], -4.1% [1-sided 97.55% CI, -∞ to -1.1%]; relative risk, 0.84 [1-sided 97.55% CI, -∞ to 0.96; P = .004]). The composite of postoperative seizure, thrombotic events, kidney dysfunction, and death occurred in 265 patients in the high-dose group (17.6%) and 249 patients in the low-dose group (16.8%) (RD, 0.8%; 1-sided 97.55% CI, -∞ to 3.9%; P = .003 for noninferiority). Fourteen of the 15 prespecified secondary end points were not significantly different between groups, including seizure, which occurred in 15 patients (1.0%) in the high-dose group and 6 patients (0.4%) in the low-dose group (RD, 0.6%; 95% CI, -0.0% to 1.2%; P = .05).

CONCLUSIONS AND RELEVANCE

Among patients who underwent cardiac surgery with cardiopulmonary bypass, high-dose compared with low-dose tranexamic acid infusion resulted in a modest statistically significant reduction in the proportion of patients who received allogeneic red blood cell transfusion and met criteria for noninferiority with respect to a composite primary safety end point consisting of 30-day mortality, seizure, kidney dysfunction, and thrombotic events.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03782350.

Tranexamic acid in cardiac surgery: Are low doses enough?

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Efficacy and Safety of Postoperative Intravenous Tranexamic Acid in Total Knee Arthroplasty: A Prospective Randomized Controlled Study

Objective

To assess the efficacy and safety of postoperative intravenous tranexamic acid (TXA) in patients undergoing total knee arthroplasty (TKA).

Methods

From March 2020 to August 2020, all patients undergoing primary unilateral TKA in our hospital were considered in prospective randomized controlled study. Included patients were randomized into three groups to receive either two doses of 15 mg/kg intravenous TXA postoperatively, at 2 and 24 h after closing the incision (group A), or a single dose of 15 mg/kg intravenous TXA 2 h postoperatively (group B), or placebo (group C). The calculated total blood loss (TBL) and hidden blood loss (HBL), incidence of venous thromboembolism (VTE), and transfusion rate were compared among groups. The levels of prothrombotic state parameters including thrombomodulin (TM), thrombin‐anti‐thrombin complex (TAT), plasmin‐anti‐plasmin complex (PIC), and tissue‐type plasminogen activator‐plasminogen activator inhibitor complex (t‐PAI·C) in plasma were measured during the perioperative period. Patients were compared depending on the Kellgren‐Lawrence classification (K‐L types III and IV).

Results

All patients were followed up for at least 4 weeks. The mean TBL and HBL in group C (1,182.45 ± 160.50; and 965.47 ± 139.61 mL, respectively) were significantly higher than those in groups A (944.34 ± 130.88 mL, P < 0.05; and 712.45 ± 129.82mL, P < 0.05, respectively) or B (995.20 ± 154.00 mL, P < 0.05; and 757.20 ± 134.39 mL, P < 0.05, respectively), but no significant differences were found between groups A and B (P > 0.05 and P > 0.05, respectively). None of the patients of three groups received blood transfusion, so there were no significant differences in blood transfusion rate among groups. Similar results were obtained with subgroups of patients who had the K‐L types III and IV. The DVT frequencies were four, three, and three in groups A, B, and C, respectively, with no significant differences after comparison (P > 0.05). There were no significant differences in the levels of prothrombotic state parameters (TM, TAT, PIC, t‐PAI·C) or incidence of VTE among groups (P > 0.05). Wound leakage was observed in five patients during the hospital stay (two patients in group A, one patient in group B, and two patients in group C), and no statistical difference was found in wound leakage or other complications among groups (P > 0.05).

Conclusions

Short‐term application of postoperative intravenous TXA in TKAs resulted in reduced HBL without a measured increase in the actual incidence of VTE or the potential risk of thrombosis, but administration of TXA after the first 24 h had no significant effect.

Antifibrinolytic Drugs for the Prevention of Bleeding in Pediatric Cardiac Surgery on Cardiopulmonary Bypass: A Systematic Review and Meta-analysis

BACKGROUND

Bleeding is one of the commonest complications affecting children undergoing cardiac surgery on cardiopulmonary bypass. Antifibrinolytic drugs are part of a multifaceted approach aimed at reducing bleeding, though sufficiently sized pediatric studies are sparse, and dosing algorithms are heterogeneous. Our objective was to evaluate the efficacy and safety of antifibrinolytic agents as well as the effectiveness of different dosing regimens in pediatric cardiac surgery using cardiopulmonary bypass.

METHODS

We performed a systematic review and meta-analysis evaluating randomized controlled trials published between 1980 and 2019, identified by searching the databases MEDLINE, EMBASE, PubMed, and CENTRAL. All studies investigating patients <18 years of age without underlying hematological disorders were included. The primary outcome was postoperative bleeding; secondary end points included blood product transfusion, mortality, and safety (thromboses, anaphylaxis, renal or neurological dysfunction, and seizures). Different dosing regimens were compared. Studies were dual appraised, outcomes were reported descriptively and, if appropriate, quantitatively using the Review Manager 5 (REVMAN 5) software (The Cochrane Collaboration).

RESULTS

Thirty of 209 articles were included, evaluating the following drugs versus control: aprotinin n = 14, tranexamic acid (TXA) n = 12, and epsilon-aminocaproic acid (EACA) n = 4. The number of participants per intervention group ranged from 11 to 100 (median, 25; interquartile range [IQR], 20.5) with a wide age span (mean, 13 days to 5.8 years) and weight range (mean, 3.1-26.3 kg). Methodological quality was low to moderate.All agents reduced mean 24-hour blood loss compared to control: aprotinin by 6.0 mL/kg (95% confidence interval [CI], -9.1 to -3.0; P = .0001), TXA by 9.0 mL/kg (95% CI, -11.3 to -6.8; P < .00001), and EACA by 10.5 mL/kg (95% CI, -21.1 to 0.0; P = .05). Heterogeneity was low for TXA (I2 = 29%; P = .19), moderate for aprotinin (I2 = 41%; P = .11), and high for EACA (I2 = 95%; P = <.00001). All agents also reduced 24-hour blood product transfusion. There was no clear dose-response effect for TXA nor aprotinin. Studies were underpowered to detect significant differences in mortality, thromboses, anaphylaxis, and renal or neurological dysfunction.

CONCLUSIONS

The available data demonstrate efficacy for all 3 antifibrinolytic drugs. Therefore, the agent with the most favorable safety profile should be used. As sufficient data are lacking, large comparative trials are warranted to assess the relative safety and appropriate dosing regimens in pediatrics.

Clinical use of tranexamic acid: evidences and controversies

Tranexamic acid (TXA) significantly reduces blood loss in a wide range of surgical procedures and improves survival rates in obstetric and trauma patients with severe bleeding. Although it mainly acts as a fibrinolysis inhibitor, it also has an anti-inflammatory effect, and may help attenuate the systemic inflammatory response syndrome found in some cardiac surgery patients. However, the administration of high doses of TXA has been associated with seizures and other adverse effects that increase the cost of care, and the administration of TXA to reduce perioperative bleeding needs to be standardized. Tranexamic acid is generally well tolerated, and most adverse reactions are considered mild or moderate. Severe events are rare in clinical trials, and literature reviews have shown tranexamic acid to be safe in several different surgical procedures. However, after many years of experience with TXA in various fields, such as orthopedic surgery, clinicians are now querying whether the dosage, route and interval of administration currently used and the methods used to control and analyze the antifibrinolytic mechanism of TXA are really optimal. These issues need to be evaluated and reviewed using the latest evidence to improve the safety and effectiveness of TXA in treating intracranial hemorrhage and bleeding in procedures such as liver transplantation, and cardiac, trauma and obstetric surgery.

Tranexamic acid in cardiac surgery: Are low doses enough?

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Multiple intravenous tranexamic acid doses in total knee arthroplasty in patients with rheumatoid arthritis: a randomized controlled study

Background

We aimed to determine the efficacy and safety of multiple doses of intravenous tranexamic acid (IV-TXA) on perioperative blood loss in patients with rheumatoid arthritis (RA) who had undergone primary unilateral total knee arthroplasty (TKA).

Methods

For this single-center, single-blind randomized controlled clinical trial, 10 male and 87 female participants with RA, aged 50–75 years, who underwent unilateral primary TKA were recruited. The patients received one dose of 1 g IV-TXA 10 min before skin incision, followed by articular injection of 1.5 g tranexamic acid after cavity suture during the surgery. The patients were randomly assigned (1:1) into two groups and received an additional single dose of IV-TXA (1 g) for 3 h (group A) or three doses of IV-TXA (1 g) for 3, 6, and 12 h (group B) postoperatively. Primary outcomes were total blood loss (TBL), hidden blood loss (HBL), and maximum hemoglobin (Hb) level decrease. Secondary outcomes were transfusion rate and D-dimer levels. All parameters were measured postoperatively during inpatient hospital stay.

Results

The mean TBL, HBL, and maximum Hb level decrease in group B (506.1 ± 227.0 mL, 471.6 ± 224.0 mL, and 17.5 ± 7.7 g/L, respectively) were significantly lower than those in group A (608.8 ± 244.8 mL, P = 0.035; 574.0 ± 242.3 mL, P = 0.033; and 23.42 ± 9.2 g/L, P = 0.001, respectively). No episode of transfusion occurred. The D-dimer level was lower in group B than in group A on postoperative day 1 (P <  0.001), and the incidence of thromboembolic events was similar between the groups (P > 0.05).

Conclusion

In patients with RA, three doses of postoperative IV-TXA further facilitated HBL and Hb level decrease without increasing the incidence of adverse events in a short period after TKA.

Trial registration

The trial was registered in the Chinese Clinical Trial Registry (ChiCTR1900025013).

Exposure-Response Relationship of Tranexamic Acid in Cardiac Surgery

BACKGROUND

It is unclear whether high-dose regimens of tranexamic acid in cardiac surgery (total dose, 80 to 100 mg/kg) confer a clinical advantage over low-dose regimens (total dose, approximately 20 mg/kg), particularly as tranexamic acid-associated seizure may be dose-related. The authors' aim was to characterize the exposure-response relationship of this drug.

METHODS

Databases were searched for randomized controlled trials of intravenous tranexamic acid in adult patients undergoing cardiopulmonary bypass surgery. Observational studies were added for seizure assessment. Tranexamic acid concentrations were predicted in each arm of each study using a population pharmacokinetic model. The exposure-response relationship was evaluated by performing a model-based meta-analysis using nonlinear mixed-effect models.

RESULTS

Sixty-four randomized controlled trials and 18 observational studies (49,817 patients) were included. Seventy-three different regimens of tranexamic acid were identified, with the total dose administered ranging from 5.5 mg/kg to 20 g. The maximum effect of tranexamic acid for postoperative blood loss reduction was 40% (95% credible interval, 34 to 47%), and the EC50 was 5.6 mg/l (95% credible interval, 0.7 to 11 mg/l). Exposure values with low-dose regimens approached the 80% effective concentration, whereas with high-dose regimens, they exceeded the 90% effective concentration. The predicted cumulative blood loss up to 48 h postsurgery differed by 58 ml between the two regimens, and the absolute difference in erythrocyte transfusion rate was 2%. Compared to no tranexamic acid, low-dose and high-dose regimens increased the risk of seizure by 1.2-fold and 2-fold, respectively. However, the absolute risk increase was only clinically meaningful in the context of prolonged open-chamber surgery.

CONCLUSIONS

In cardiopulmonary bypass surgery, low-dose tranexamic acid seems to be an appropriate regimen for reducing bleeding outcomes. This meta-analysis has to be interpreted with caution because the results are observational and dependent on the lack of bias of the predicted tranexamic acid exposures and the quality of the included studies.

EDITOR’S PERSPECTIVE

Impact of Obesity on Tranexamic Acid Efficacy in Adult Patients With Major Bleeding

BACKGROUND

Tranexamic acid (TXA) is an antifibrinolytic used for prophylaxis and treatment of acute bleeding. Although fixed dosing is often used in practice, weight-based dosing is sometimes used in the operating room (OR). The efficacy and safety of fixed-dose TXA is not well established in patients with above average weight or body mass index.

OBJECTIVE

To characterize the efficacy and safety of intravenous TXA in obese patients with major bleeding.

METHODS

This was a retrospective review of 165 patients receiving fixed-dose TXA for acute bleeding outside the OR. Blood product administration (BPA) before and after TXA was collected, along with demographic and bleed-related information. Thrombotic events were the major safety end point. A prespecified subgroup analysis was conducted in patients weighing at least 100 kg compared with a lower weight. Logistic regression was performed to determine whether an association exists between body weight and blood product requirement after TXA administration.

RESULTS

In the 24 hours after TXA, patients received an average of 4.17 units of blood product. Patients weighing at least 100 kg averaged 4.04 total units, compared with 4.19 units in the lower weight group (P = 0.603). Administration of individual blood products did not differ between groups, and thrombotic events were similar. Regression analysis did not associate weight with total BPA.

CONCLUSION AND RELEVANCE

In patients receiving fixed-dose TXA, weight does not appear to alter blood product requirements or rates of adverse thrombotic events. These data support continued use of fixed-dose TXA for treatment of acute major bleeding in obese patients.

[Progress on the application of tranexamic acid in adolescent spine corrective surgery]

Objective

To review the advances in the application of tranexamic acid (TXA) in adolescent spinal corrective surgery.

Methods

The mechanism of action and pharmacokinetic, effectiveness, dosage, safety as well as methods of administration were comprehensively summarized by consulting domestic and overseas related literature about the application of TXA in adolescent spinal corrective surgery in recent years.

Results

TXA efficaciously reduce intraoperative blood loss, transfusion rate and volume, postoperative drainage volume in adolescent spinal corrective surgery. At present, the most common method of administration in adolescent spinal corrective surgery is that a loading dose is given intravenously before skin incision or induction of anesthesia, followed by a maintenance dose until the end of the surgery. The range of loading dose and maintenance dose is 10-100 mg/kg and 1-10 mg/(kg·h), respectively. No drug related adverse event has been reported in this range.

Conclusion

The effectiveness and safety of TXA in adolescent spinal surgery have been basically confirmed. However, further studies are needed to determine the optimal dosage, method of administration as well as whether it could reduce blood loss after surgery.

Outcome impact of different tranexamic acid regimens in cardiac surgery with cardiopulmonary bypass (OPTIMAL): Rationale, design, and study protocol of a multicenter randomized controlled trial

Tranexamic acid (TxA) reduces perioperative blood transfusion in cardiac surgery; however, the optimal dose of TxA remains unknown. METHODS AND RESULTS: This large-scale, double-blind, randomized controlled trial with a 1-year follow-up enrolls patients undergoing elective cardiac surgery with cardiopulmonary bypass. Patients are randomly assigned 1:1 into either the high-dose TxA group (intravenous bolus [30 mg/kg] after anesthesia followed by intravenous maintenance [16 mg/kg/h] throughout the operation, and a pump prime dose of 2 mg/kg) or the low-dose TxA group (intravenous bolus and maintenance are 10 mg/kg and 2 mg/kg/h, respectively, and a pump prime dose of 1 mg/kg). The primary efficacy end point is the rate of perioperative allogeneic red blood cell (RBC) transfusion defined as the number (%) of patients who will receive at least 1 RBC unit from operation day to discharge. The primary safety end point is the 30-day rate of the composite of perioperative seizures, renal dysfunction, myocardial infarction, ischemic stroke, deep vein thrombosis, pulmonary embolism, and all-cause mortality. The secondary end points are perioperative allogeneic RBC transfusion volume, the non-RBC blood transfusion rate, postoperative bleeding, reoperation rate, mechanical ventilation duration, intensive care unit stay, hospital length of stay, total hospitalization cost, each component of composite primary safety end point, and the 6-month/1-year follow-up mortality and morbidity. We estimated a sample size of 3,008 participants. CONCLUSIONS: The study is designed to identify a TxA dose with maximal efficacy and minimal complications. We hypothesize that the high dose has superior efficacy and noninferior safety to the low dose.

Tortuosity-powered microfluidic device for assessment of thrombosis and antithrombotic therapy in whole blood

Accurate assessment of blood thrombosis and antithrombotic therapy is essential for the management of patients in a variety of clinical conditions, including surgery and on extracorporeal life support. However, current monitoring devices do not measure the effects of hemodynamic forces that contribute significantly to coagulation, platelet function and fibrin formation. This limits the extent to which current assays can predict clotting status in patients. Here, we demonstrate that a biomimetic microfluidic device consisting stenosed and tortuous arteriolar vessels would analyze blood clotting under flow, while requiring a small blood volume. When the device is connected to an inline pressure sensor a clotting time analysis is applied, allowing for the accurate measurement of coagulation, platelets and fibrin content. Furthermore, this device detects a prolonged clotting time in clinical blood samples drawn from pediatric patients on extracorporeal membrane oxygenation receiving anticoagulant therapy. Thus, this tortuosity activated microfluidic device could lead to a more quantitative and rapid assessment of clotting disorders and their treatment.

The Effect of Tranexamic Acid Administration on Perioperative Bleeding in Patients Undergoing Knee or Hip Arthroplasty: A Single-Centre Retrospective Study

Objective

Tranexamic acid (TXA) has been used to reduce perioperative bleeding in various surgeries because of its antifibrinolytic effect. Recently, patients undergoing orthopaedic surgery in our institution received a loading dose of TXA (10 00 mg) before surgery, followed by 100 mg h⁻¹ until the end of surgery. The purpose of the present study was to evaluate the efficacy of TXA administration on the perioperative blood loss in patients undergoing knee arthroplasty or hip arthroplasty.

Methods

A retrospective cross-sectional study was conducted for the records in patients who underwent surgery without TXA administration (control group) and patients who underwent surgery with TXA administration (TXA group). Amount of intraoperative blood loss, intraoperative infusion volume, intraoperative blood transfusion volume, postoperative blood transfusion volume, changes in haemoglobin concentrations (ΔHb) and estimated blood loss were collected. Data were adjusted by propensity score method.

Results

A total of 126 (63 in the control group and 63 in the TXA group) patients were included during the study period. Intraoperative infusion, postoperative transfusion, ΔHb and estimated blood loss were significantly reduced in the TXA group, although there were no significant differences in the volumes of intraoperative transfusion and blood loss.

Conclusion

The administration of TXA (loading dose of 1000 mg and continuous infusion of 100 mg h⁻¹) reduced postoperative transfusion and perioperative blood loss. These results indicated that TXA administration is useful for reducing perioperative blood loss in patients undergoing knee or hip arthroplasty.

Introduction of a standardised protocol, including systematic use of tranexamic acid, for management of severe adult trauma patients in a low-resource setting: the MSF experience from Port-au-Prince, Haiti

Background

Bleeding is an important cause of death in trauma victims. In 2010, the CRASH-2 study, a multicentre randomized control trial on the effect of tranexamic acid (TXA) administration to trauma patients with suspected significant bleeding, reported a decreased mortality in randomized patients compared to placebo. Currently, no evidence on the use of TXA in humanitarian, low-resource settings is available. We aimed to measure the hospital outcomes of adult patients with severe traumatic bleeding in the Médecins Sans Frontières Tabarre Trauma Centre in Port-au-Prince, Haiti, before and after the implementation of a Massive Haemorrhage protocol including systematic early administration of TXA.

Methods

Patients admitted over comparable periods of four months (December2015- March2016 and December2016 - March2017) before and after the implementation of the Massive Haemorrhage protocol were investigated. Included patients had blunt or penetrating trauma, a South Africa Triage Score ≥ 7, were aged 18–65 years and were admitted within 3 h from the traumatic event. Measured outcomes were hospital mortality and early mortality rates, in-hospital time to discharge and time to discharge from intensive care unit.

Results

One-hundred and sixteen patients met inclusion criteria. Patients treated after the introduction of the Massive Haemorrhage protocol had about 70% less chance of death during hospitalization compared to the group “before” (adjusted odds ratio 0.3, 95%confidence interval 0.1–0.8). They also had a significantly shorter hospital length of stay (p = 0.02).

Conclusions

Implementing a Massive Haemorrhage protocol including early administration of TXA was associated with the reduced mortality and hospital stay of severe adult blunt and penetrating trauma patients in a context with poor resources and limited availability of blood products.

Topical tranexamic acid inhibits fibrinolysis more effectively when formulated with self-propelling particles

BACKGROUND

Endogenous fibrinolytic activation contributes to coagulopathy and mortality after trauma. Administering tranexamic acid (TXA), an antifibrinolytic agent, is one strategy to reduce bleeding; however, it must be given soon after injury to be effective and minimize adverse effects. Administering TXA topically to a wound site would decrease the time to treatment and could enable both local and systemic delivery if a suitable formulation existed to deliver the drug deep into wounds adequately.

OBJECTIVES

To determine whether self-propelling particles could increase the efficacy of TXA.

METHODS

Using previously developed self-propelling particles, which consist of calcium carbonate and generate CO2 gas, TXA was formulated to disperse in blood and wounds. The antifibrinolytic properties were assessed in vitro and in a murine tail bleeding assay. Self-propelled TXA was also tested in a swine model of junctional hemorrhage consisting of femoral arteriotomy without compression.

RESULTS

Self-propelled TXA was more effective than non-propelled formulations in stabilizing clots from lysis in vitro and reducing blood loss in mice. It was well tolerated when administered subcutaneously in mice up to 300 to 1000 mg/kg. When it was incorporated in gauze, four of six pigs treated after a femoral arteriotomy and without compression survived, and systemic concentrations of TXA reached approximately 6 mg/L within the first hour.

CONCLUSIONS

A formulation of TXA that disperses the drug in blood and wounds was effective in several models. It may have several advantages, including supporting local clot stabilization, reducing blood loss from wounds, and providing systemic delivery of TXA. This approach could both improve and simplify prehospital trauma care for penetrating injury.

Efficacy and Safety of Tranexamic Acid in Intertrochanteric Fractures: A Single-Blind Randomized Controlled Trial

Objective

To investigate the efficacy and safety of tranexamic acid (TXA) in the reduction of bleeding and the need for transfusion in elderly intertrochanteric fracture patients.

Methods

A total of 100 patients with intertrochanteric fractures undergoing surgery were enrolled and randomly allocated to the TXA group in which patients (75.10 ± 8.27 years old) were treated with 1 g of TXA, or the control group (77.82 ± 6.42 years old) treated with a placebo. Surgery was performed by two senior orthopaedic surgeons from two institutions. The proximal femoral nail antirotation (PFNA) was conducted using the standard procedure. Three outcome measures, including blood loss, transfusion, and complications, were recorded. Blood loss and transfusion were investigated to assess TXA's effectiveness, while complications were investigated to assess TXA's safety. Statistical indicators for blood loss included total, intraoperative, postoperative, and hidden blood loss volumes, calculated by hemoglobin levels, hematocrit levels, and drainage volume. The number and amount of blood transfusions were recorded. Complications associated with surgery, including deep vein thrombosis, pulmonary embolism, wound hematoma, wound infection, cardiovascular and cerebrovascular accidents, and respiratory infections, were also recorded.

Results

All patients were followed up for 1 month after surgery. There were no significant differences in demographic and clinical characteristics between the two groups. The TXA group suffered significantly less total blood loss (563.37 ± 197.51 vs 819.25 ± 273.96 mL, 95% CI: −349.49 to −162.27, P < 0.01), intraoperative blood loss (140.3 ± 80.64 vs 230.5 ± 130.56 mL, 95% CI −132.74 to −47.66, P < 0.01), and hidden blood loss (410.42 ± 178.23 vs 571.19 ± 218.13 mL, 95% CI: −238.85 to −82.69, P < 0.01) than the control group. However, postoperative total blood loss was not significantly different (97.5 ± 20.93 vs 94.7 ± 35.78 mL; P = 0.63). A total of 5 patients from the TXA group and 27 from the control group received packed RBC for postoperative transfusion, but the mean number of transfusion units was not significantly different between groups. Complications including deep vein thrombosis, pulmonary embolism, myocardial infarction, ischemic cerebral infarction, hematoma, and infection were observed in both groups, but no significant differences were found.

Conclusions

In intertrochanteric fracture surgery performed using PFNA, intravenous administration of TXA significantly reduced the risk of intraoperative, total and hidden blood loss, in addition to the need for allogeneic transfusion, without increasing the rate of complications.

[Efficacy and safety of a loading high-dose tranexamic acid followed by postoperative five doses in total hip arthroplasty: A randomized controlled trial]

OBJECTIVE

To evaluate the efficacy and safety of a loading high-dose tranexamic acid (TXA) followed by postoperative 5 doses in total hip arthroplasty (THA) by a randomized controlled trial.

METHODS

Seventy-two patients who underwent primary unilateral THA between December 2017 and March 2018 were randomly divided into two groups (36 patients in each group). A single dose of 20 mg/kg TXA was administered intravenously before 5-10 minutes of operation in group A; and a single dose of 40 mg/kg TXA was administered intravenously in group B at the same time point. All patients received 5 doses of 1 g TXA at 3, 6, 12, 18, and 24 hours after the first dose. There was no significant difference in gender, age, weight, height, body mass index, disease type, and combined medical diseases between the two groups ( P>0.05). Total blood loss (TBL), lowest postoperative hemoglobin (Hb) level, fibrinolysis parameters [fibrin (ogen) degradation products (FDP), D-dimer], inflammatory factors [C-reaction protein (CRP), interleukin-6 (IL-6)], adverse events (thrombosis, pulmonary embolism) were recorded and compared between groups.

RESULTS

The TBL was significantly lower in group B than in group A ( P<0.05). Furthermore, the lowest postoperative Hb level was significantly higher in group B than in group A ( P<0.05). There was no significant difference in FDP and D-dimer before operation between the two groups ( P>0.05). The levels of FDP and D-dimer were significantly lower in group B than in group A at 12 and 36 hours postoperatively ( P<0.05). There was no significant difference in CRP and IL-6 before operation between the two groups ( P>0.05). The levels of CRP and IL-6 were significant lower in group B than in group A at 12, 24, and 36 hours postoperatively ( P<0.05). There was no significant difference at 14 days ( P>0.05). There were 2 patients with intramuscular venous thrombosis in group A and 1 in group B after operation, and there was no significant difference in the incidence of embolic events ( P>0.05). No deep venous thrombosis or pulmonary embolism occurred in all groups.

CONCLUSION

A loading high-dose TXA followed by postoperative 5 doses can further reduce the blood loss, provide additional fibrinolysis and inflammation control in THA, without increasing the risk of embolic events.

The Use of Tranexamic Acid to Reduce Surgical Blood Loss: A Review Basic Science, Subspecialty Studies, and The Evolution of Use in Spine Deformity Surgery

Significant blood loss is often seen in orthopedic surgeries, especially complex spinal procedures that constitute long surgical times, large incisions, and rich blood supplies. Tranexamic acid (TXA), a synthetic analog of the amino acid lysine, has proven to be a cost-effective method in decreasing transfusion rates and avoiding complications associated with low blood volume. Recent data on TXA's use in spine surgery suggest that TXA remains both efficacious and safe, although the ideal dosing and timing of administration is still a point of disagreement. The purpose of this study is to review the literature for the use of TXA in spine surgery to better understand its safety profile and ideal dosage. This narrative review on TXA was conducted on prospective orthopedic studies that used TXA in spine deformity surgery. TXA in adult and pediatric spine surgery has decreased intraoperative and postoperative blood loss, decreasing the need for blood transfusions. The most common dose in the literature is a 10 mg/kg loading dose, followed by 1 mg/kg per hour. Although the proper dosing of TXA for spine surgery remains debatable, studies have proven that TXA is effective at reducing blood loss without increasing the risk of thrombotic events.

The antifibrinolytic and anti-inflammatory effects of multiple doses of oral tranexamic acid in total knee arthroplasty patients: a randomized controlled trial

Essentials Perioperative blood loss and inflammatory response can significantly affect recovery after surgery. We studied the effects of multiple-dose oral tranexamic acid on blood loss and inflammatory response. A postoperative four-dose regimen brought about maximum reduction in postoperative blood loss. A postoperative four-dose regimen reduced inflammatory response and promoted early rehabilitation. SUMMARY: Background Tranexamic acid (TXA) can reduce blood loss and the inflammatory response at multiple doses in total knee arthroplasty patients. However, the optimal regimen has not been determined. Objectives To identify the most effective regimen for achieving maximum reductions in blood loss and the inflammatory response. Patients/Methods Two hundred and seventy-five patients were randomized to receive a placebo (group A), a single 2-g oral dose of TXA 2 h preoperatively followed by 1 g of oral TXA 3 h postoperatively (group B), a single dose followed by 1 g of oral TXA 3 h and 7 h postoperatively (group C), a single dose followed by 1 g of oral TXA 3 h, 7 h and 11 h postoperatively (group D), or a single dose followed by 1 g of oral TXA 3 h, 7 h, 11 h and 15 h postoperatively (group E). The primary outcome was total blood loss on postoperative day (POD) 3. Secondary outcomes included a decrease in the hemoglobin level, coagulation parameters, inflammatory marker levels, and thromboembolic complications. Results Groups D and E had significantly lower blood loss and smaller decreases in hemoglobin level than groups A, B, and C, with no significant difference on POD 3 between groups D and E. Significantly enhanced coagulation was identified for the four multiple-dose regimens; however, all thromboelastographic parameters remained within normal ranges. Group E had the lowest inflammatory marker levels and pain, and the greatest range of motion. No thromboembolic complications were identified. Conclusion The four-dose regimen yielded the maximum reductions in blood loss and inflammatory response, improved analgesia, and promoted early rehabilitation. Further studies are required to ensure that these findings are reproducible.

Antifibrinolytic Therapy and Perioperative Considerations

Fibrinolysis is a physiologic component of hemostasis that functions to limit clot formation. However, after trauma or surgery, excessive fibrinolysis may contribute to coagulopathy, bleeding, and inflammatory responses. Antifibrinolytic agents are increasingly used to reduce bleeding, allogeneic blood administration, and adverse clinical outcomes. Tranexamic acid is the agent most extensively studied and used in most countries. This review will explore the role of fibrinolysis as a pathologic mechanism, review the different pharmacologic agents used to inhibit fibrinolysis, and focus on the role of tranexamic acid as a therapeutic agent to reduce bleeding in patients after surgery and trauma.

Self-Propelled Dressings Containing Thrombin and Tranexamic Acid Improve Short-Term Survival in a Swine Model of Lethal Junctional Hemorrhage

Hemorrhage is the leading cause of preventable death in trauma, and hemorrhage from noncompressible junctional anatomic sites is particularly difficult to control. The current standard is QuikClot Combat Gauze packing, which requires 3 min of compression. We have created a novel dressing with calcium carbonate microparticles that can disperse and self-propel upstream against flowing blood. We loaded these microparticles with thrombin and tranexamic acid and tested their efficacy in a swine arterial bleeding model without wound compression. Anesthetized immature female swine received 5 mm femoral arteriotomies to induce severe junctional hemorrhage. Wounds were packed with kaolin-based QuikClot Combat Gauze (KG), propelled thrombin-microparticles with protonated tranexamic acid (PTG), or a non-propelling formulation of the same thrombin-microparticles with non-protonated tranexamic acid (NPTG). Wounds were not compressed after packing. Each animal then received one 15 mL/kg bolus of hydroxyethyl starch solution followed by Lactated Ringer as needed for hypotension (maximum: 100 mL/kg) for up to 3 h. Survival was improved with PTG (3-h survival: 8/8, 100%) compared with KG (3/8, 37.5%) and NPTG (2/8, 25%) (P <0.01). PTG animals maintained lower serum lactate and higher hemoglobin concentrations than NPTG (P <0.05) suggesting PTG decreased severity of subsequent hemorrhagic shock. However, total blood loss, Lactated Ringer infusion volumes, and mean arterial pressures of surviving animals were not different between groups (P >0.05). Thus, in this swine model of junctional arterial hemorrhage, gauze with self-propelled, prothrombotic microparticles improved survival and 2 indicators of hemorrhagic shock when applied without compression, suggesting this capability may enable better treatment of non-compressible junctional wounds.

Comparison of topical and intravenous administration of tranexamic acid for blood loss control during total joint replacement: Review of literature

Purpose

Many randomised controlled trials and meta-analysis studies have presented the efficacy of tranexamic acid (TXA) without an increase of complications. However, questions still remain about the type of administration, optimal dose and secondary outcomes of TXA in total hip arthroplasty and total knee arthroplasty. The aim of this review is to summarise the existing information in literature concerning the pharmacological characteristics of TXA, forms, doses, types of application and contraindications for its use.

Methods

A literature review containing 63 articles from the PubMed data starting from the first description of tranexamic acid until now was made in trying to present the existing information in a simple and effective way.

Results

TXA leads to statistically significant reduction of peri and postoperative bleeding and in that way decreases blood transfusion rates and the infection risk. Topical and intravenous (IV) use of TXA revealed similar results, with no increase of deep venous thrombosis. Therefore, topical TXA could be a reasonable alternative in patients with contraindications for IV application of TXA.

Conclusions

Blood loss control with TXA, a synthetic analogue of the amino acid lysine, may be an excellent and safe alternative to allogeneic blood transfusion after total hip arthroplasty and total knee arthroplasty. Further studies are needed to establish the efficacy of combined IV and topical administration of TXA with regard to diminishing blood loss and reducing hospital stay.

The Translational Potential of this Article

This review briefly presents the pharmacological characteristics of TXA, forms, doses, types of application and contraindications for its use with regard to diminishing blood loss and reducing hospital stay for better therapeutic strategies in orthopaedics.

Single intravenous bolus versus perioperative continuous infusion of tranexamic acid to reduce blood loss in abdominal oncosurgical procedures: A prospective randomized double-blind clinical study

Background and Aims:

Intraoperative use of a single bolus dose of tranexamic acid may not be sufficient to prevent bleeding in the early postoperative period. The present study was carried out to compare the effect of two dose regimens of tranexamic acid in reducing perioperative blood loss and the amount of allogenic blood transfusion in abdominal tumor surgery.

Material and Methods:

In this prospective, controlled, and double-blind investigation, 60 patients electively posted for abdominal oncosurgical procedures were randomly assigned to receive a single bolus dose of tranexamic acid (10 mg/kg) (Group A), a bolus dose of tranexamic acid (10 mg/kg) followed by infusion (1 mg/kg/h) till 4 h postoperatively (Group B), and a bolus followed by infusion of normal saline (group C). Total intraoperative blood loss, amount of allogenic blood transfusion, postoperative drain collections, and hemoglobin and hematocrit levels were recorded at different time intervals. Data obtained after comparing three groups were analyzed by analysis of variance test for variables following normal distribution, Kruskal–Wallis test for nonparametric data, and post-hoc Tukey–Kramer test for intergroup analysis. A probability value of less than 5% was considered significant.

Results:

There was no significant difference in intraoperative blood loss in all the three groups. Both the tranexamic acid groups showed reduction in postoperative blood collection in drain at 6 h and 24 h in comparison to the control group (P < 0.001). There was also a significant difference in the amount of blood in postoperative drain at 24 h within the tranexamic acid groups, where lesser collection was seen in the infusion group (P = 0.007). Hemoglobin and hematocrit levels measured at different postoperative time intervals showed a significant reduction from the baseline in the control group compared to the tranexamic acid groups together.

Conclusion:

Tranexamic acid causes more effective reduction in post-operative blood loss when used as a bolus followed by an infusion continued in the postoperative period in comparison to its use as a single intravenous bolus in abdominal tumor surgery.

Is tranexamic acid exposure related to blood loss in hip arthroplasty? A pharmacokinetic-pharmacodynamic study

AIMS

Tranexamic acid (TXA) is an antifibrinolytic agent, decreasing blood loss in hip arthroplasty. The present study investigated the relationship between TXA exposure markers, including the time above the in vitro threshold reported for inhibition of fibrinolysis (10 mg l^-1 ), and perioperative blood loss.

METHODS

Data were obtained from a prospective, double-blind, parallel-arm, randomized superiority study in hip arthroplasty. Patients received a preoperative intravenous bolus of TXA 1 g followed by a continuous infusion of either TXA 1 g or placebo over 8 h. A population pharmacokinetic study was conducted to quantify TXA exposure.

RESULTS

In total, 827 TXA plasma concentrations were measured in 166 patients. A two-compartment model fitted the data best, total body weight determining interpatient variability in the central volume of distribution. Creatinine clearance accounted for interpatient variability in clearance. At the end of surgery, all patients had TXA concentrations above the therapeutic target of 10 mg l^-1 . The model-estimated time during which the TXA concentration was above 10 mg l^-1 ranged from 3.3 h to 16.3 h. No relationship was found between blood loss and either the time during which the TXA concentration exceeded 10 mg l^-1 or the other exposure markers tested (maximum plasma concentration, area under the concentration-time curve).

CONCLUSION

In hip arthroplasty, TXA plasma concentrations were maintained above 10 mg l^-1 during surgery and for a minimum of 3 h with a preoperative TXA dose of 1 g. Keeping TXA concentrations above this threshold up to 16 h conferred no advantage with regard to blood loss.

High Concentrations of Tranexamic Acid Inhibit Ionotropic Glutamate Receptors

BACKGROUND

The antifibrinolytic drug tranexamic acid is structurally similar to the amino acid glycine and may cause seizures and myoclonus by acting as a competitive antagonist of glycine receptors. Glycine is an obligatory co-agonist of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors. Thus, it is plausible that tranexamic acid inhibits NMDA receptors by acting as a competitive antagonist at the glycine binding site. The aim of this study was to determine whether tranexamic acid inhibits NMDA receptors, as well as α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate subtypes of ionotropic glutamate receptors.

METHODS

Tranexamic acid modulation of NMDA, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and kainate receptors was studied using whole cell voltage-clamp recordings of current from cultured mouse hippocampal neurons.

RESULTS

Tranexamic acid rapidly and reversibly inhibited NMDA receptors (half maximal inhibitory concentration = 241 ± 45 mM, mean ± SD; 95% CI, 200 to 281; n = 5) and shifted the glycine concentration-response curve for NMDA-evoked current to the right. Tranexamic acid also inhibited α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (half maximal inhibitory concentration = 231 ± 91 mM; 95% CI, 148 to 314; n = 5 to 6) and kainate receptors (half maximal inhibitory concentration = 90 ± 24 mM; 95% CI, 68 to 112; n = 5).

CONCLUSIONS

Tranexamic acid inhibits NMDA receptors likely by reducing the binding of the co-agonist glycine and also inhibits α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate receptors. Receptor blockade occurs at high millimolar concentrations of tranexamic acid, similar to the concentrations that occur after topical application to peripheral tissues. Glutamate receptors in tissues including bone, heart, and nerves play various physiologic roles, and tranexamic acid inhibition of these receptors may contribute to adverse drug effects.

Pharmacological management of perioperative bleeding in cardiac surgery

[first paragraph of article]In spite of the growing discoveries in cardiac surgery, perioperative bleeding remains one of the most common causes of morbidity and mortality. Around 50-60% of cardiac surgery patients receive blood transfusions, which are harmful and strongly associated with increased morbidity, mortality, hospital stay, and hospital cost. Patients taken back to the OR for re-exploration and control of bleeding after cardiac surgery, have a four-fold increase in the incidence of sternal infection and mortality.

Efficacy and Safety of Tranexamic Acid in Prehospital Traumatic Hemorrhagic Shock: Outcomes of the Cal-PAT Study

INTRODUCTION

The California Prehospital Antifibrinolytic Therapy (Cal-PAT) study seeks to assess the safety and impact on patient mortality of tranexamic acid (TXA) administration in cases of trauma-induced hemorrhagic shock. The current study further aimed to assess the feasibility of prehospital TXA administration by paramedics within the framework of North American emergency medicine standards and protocols.

METHODS

This is an ongoing multi-centered, prospective, observational cohort study with a retrospective chart-review comparison. Trauma patients identified in the prehospital setting with signs of hemorrhagic shock by first responders were administered one gram of TXA followed by an optional second one-gram dose upon arrival to the hospital, if the patient still met inclusion criteria. Patients administered TXA make up the prehospital intervention group. Control group patients met the same inclusion criteria as TXA candidates and were matched with the prehospital intervention patients based on mechanism of injury, injury severity score, and age. The primary outcomes were mortality, measured at 24 hours, 48 hours, and 28 days. Secondary outcomes measured included the total blood products transfused and any known adverse events associated with TXA administration.

RESULTS

We included 128 patients in the prehospital intervention group and 125 in the control group. Although not statistically significant, the prehospital intervention group trended toward a lower 24-hour mortality rate (3.9% vs 7.2% for intervention and control, respectively, p=0.25), 48-hour mortality rate (6.3% vs 7.2% for intervention and control, respectively, p=0.76), and 28-day mortality rate (6.3% vs 10.4% for intervention and control, respectively, p=0.23). There was no significant difference observed in known adverse events associated with TXA administration in the prehospital intervention group and control group. A reduction in total blood product usage was observed following the administration of TXA (control: 6.95 units; intervention: 4.09 units; p=0.01).

CONCLUSION

Preliminary evidence from the Cal-PAT study suggests that TXA administration may be safe in the prehospital setting with no significant change in adverse events observed and an associated decreased use of blood products in cases of trauma-induced hemorrhagic shock. Given the current sample size, a statistically significant decrease in mortality was not observed. Additionally, this study demonstrates that it may be feasible for paramedics to identify and safely administer TXA in the prehospital setting.

[Effect on time of temporarily-closed wound drainage on blood loss of primary total knee arthroplasty after intravenous and intra-articular injection of tranexamic acid]

Objective

To investigate the effect and safety of time of temporarily-closed wound drainage on blood loss of primary total knee arthroplasty (TKA) after intravenous and intra-articular injection of tranexamic acid (TXA).

Methods

Eighty female patients were selected from 102 patients who underwent primary TKA between September 2015 and July 2016, who were randomly divided into 4 groups: control group (group A), 30 minutes group (group B), 60 minutes group (group C), and 90 minutes group (group D), 20 patients each group. No significant difference was found in age, body mass index, side, pathogen, duration, and preoperative hemoglobin, albumin, and hematocrit between 4 groups ( P>0.05). All the patients received intravenous injection of 1 g TXA at 10 minutes before removing the tourniquet. The patients in group A were injected with 60 mL normal saline into the articular cavity and closed drainage after surgery, while the patients in groups B, C, and D were injected with 60 mL TXA into the articular cavity and closed drainage for 30, 60, and 90 minutes respectively. The volume of drainage at 24 hours after operation, the total blood loss, the postoperative hemoglobin level, maximum hemoglobin loss, albumin loss, the volume and frequency of blood transfusion, venous thrombo embolism rate, and pulmonary embolism rate were recorded and compared between groups.

Results

The volume of drainage and total blood loss in groups B, C, and D were less than those of group A, showing significant difference between groups C, D and group A ( P<0.05), but no significant difference between group B and group A ( P>0.05). The volume of drainage at 24 hours after operation in group B was higher than that in groups C and D, showing significant difference between groups B and D ( P<0.05), but no significant difference was found between groups C and D ( P>0.05). There was no significant difference in the total blood loss between groups B, C, and D ( P>0.05). The hemoglobin loss and albumin loss gradually decreased from groups A to D, but no significant difference was found between groups ( P>0.05). No venous thrombo embolism and pulmonary embolism occurred. The hemoglobin value decreased to 28 g/L at 3 days after operation in 1 patient of group D, who received venous transfusion of 20 g human albumin.

Conclusion

Intravenous and topical application of TXA in TKA can significantly decrease postoperative bleeding. Topical TXA combined with 60 minutes temporarily-closed wound drainage may reduce postoperative blood loss to the greatest extent without increasing the risk of venous thrombo and pulmonary embolism event after TKA．.

Impact of tranexamic acid on coagulation and inflammation in murine models of traumatic brain injury and hemorrhage

BACKGROUND

Posttraumatic coagulopathy and inflammation can exacerbate secondary cerebral damage after traumatic brain injury (TBI). Tranexamic acid (TXA) has been shown clinically to reduce mortality in hemorrhaging and head-injured trauma patients and has the potential to mitigate secondary brain injury with its reported antifibrinolytic and antiinflammatory properties. We hypothesized that TXA would improve posttraumatic coagulation and inflammation in a murine model of TBI alone and in a combined injury model of TBI and hemorrhage (TBI/H).

METHODS

An established murine weight drop model was used to induce a moderate TBI. Mice were administered intraperitoneal injections of 10 mg/kg TXA or equivalent volume of saline 10 min after injury. An additional group of mice was subjected to TBI followed by hemorrhagic shock using a pressure-controlled model. TBI/H mice were given intraperitoneal injections of TXA or saline during resuscitation. Blood was collected at intervals after injury to assess coagulation by rotational thromboelastometry (ROTEM) and inflammation by Multiplex cytokine analysis. Soluble P-selectin, a biomarker of platelet activation, and serum neuron-specific enolase, a biomarker of cerebral injury, were measured at intervals. Brain homogenates were analyzed for inflammatory changes by Multiplex enzyme-linked immunosorbent assay, and splenic tissue was collected for splenic cell population assessment by flow cytometry.

RESULTS

There were no coagulation, serum or cerebral cytokine, P-selectin, or neuron-specific enolase differences between mice treated with TXA or saline after TBI. After the addition of hemorrhagic shock and resuscitation to TBI, TXA administration still did not affect coagulation parameters, systemic or cerebral inflammation, or platelet activation, as compared with saline alone. At 24 hours after TBI, mice given TXA demonstrated lower splenic total cell counts central memory CD8, effector CD8, B cell, and increased naive CD4 cell populations. By contrast, TXA did not affect splenic leukocyte populations after combined TBI/H.

CONCLUSIONS

Despite clinical data suggesting a mortality benefit, TXA did not modulate coagulation, inflammation, or biomarker generation in either the TBI or TBI/H murine models. Administration of TXA after TBI altered splenic leukocyte populations, which may contribute to a change in posttraumatic immune status. Future studies should be done to investigate the role of TXA in the development of posttraumatic immunosuppression and risk of nosocomial infections.

Pharmacokinetics of tranexamic acid in neonates and infants undergoing cardiac surgery

AIM

Tranexamic acid (TXA) continues to be one of the antifibrinolytics of choice during paediatric cardiac surgery. However, in infants less than 1 year of age, the optimal dosing based on pharmacokinetic (PK) considerations is still under discussion.

METHODS

Forty-three children less than 1 year of age were enrolled, of whom 37 required the use of cardiopulmonary bypass (CPB) and six were operated on without CPB. Administration of 50 mg kg^-1 TXA intravenously at the induction of anaesthesia was followed by 50 mg kg^-1 into the CPB prime in the CPB group. Plasma concentrations of TXA were analysed by gas chromatography-mass spectrometry. PK data were investigated using nonlinear mixed-effect models.

RESULTS

A two-compartment model was fitted, with the main covariates being allometrically scaled bodyweight, CPB, postmenstrual age (PMA). Intercompartmental clearance (Q), peripheral volume (V2), systemic clearance, (CL) and the central volume (V1) were calculated. Typical values of the PK parameter estimates were as follows: CL = 3.78 [95 % confidence interval (CI) 2.52, 5.05] l h^-1 ; central volume of distribution = 13.6 (CI 11.7, 15.5) l; Q = 16.3 (CI 13.5, 19.2) l h^-1 ; V2 = 18.0 (CI 16.1, 19.9) l. Independently of age, 10 mg kg^-1 TXA as a bolus, a subsequent infusion of 10 mg kg^-1 h^-1 , then a 4 mg kg^-1 bolus into the prime and a reduced infusion of 4 mg kg^-1 h^-1 after the start of CPB are required to maintain TXA concentrations continuously above 20 μg ml^-1 , the threshold value for an effective inhibition of fibrinolysis and far lower than the usual peak concentrations (the '10-10-4-4 rule').

CONCLUSIONS

The introduction of a modified dosing regimen using a starting bolus followed by an infusion and a CPB prime bolus would prohibit the potential risk of seizures caused by high peak concentrations and also maintain therapeutic plasma concentration above 20 μg ml^-1 .

Tranexamic acid reduces blood loss in patients with extracapsular fractures of the hip: results of a randomised controlled trial

AIMS

We chose unstable extra-capsular hip fractures as our study group because these types of fractures suffer the largest blood loss. We hypothesised that tranexamic acid (TXA) would reduce total blood loss (TBL) in extra-capsular fractures of the hip.

PATIENTS AND METHODS

A single-centre placebo-controlled double-blinded randomised clinical trial was performed to test the hypothesis on patients undergoing surgery for extra-capsular hip fractures. For reasons outside the control of the investigators, the trial was stopped before reaching the 120 included patients as planned in the protocol.

RESULTS

In all 72 patients (51 women, 21 men; 33 patients in the TXA group, 39 in the placebo group) were included in the final analysis, with a significant mean reduction of 570.8 ml (p = 0.029) in TBL from 2100.4 ml (standard deviation (sd) = 1152.6) in the placebo group to 1529.6 ml (sd = 1012.7) in the TXA group. The 90-day mortality was 27.2% (n = 9) in the TXA group and 10.2% (n = 4) in the placebo group (p = 0.07). We were not able to ascertain a reliable cause of death in these patients.

DISCUSSION

TXA significantly reduced TBL in extra-capsular hip fractures, but concerns regarding its safety in this patient group must be investigated further before the use of TXA can be recommended.

TAKE HOME MESSAGE

We present a randomised clinical trial that is unique in the literature. We evaluate the effect of TXA in very homogenous population - extra-capsular fractures operated with short intramedullary nails. Cite this article: Bone Joint J 2016;98-B:747-53.

Using antifibrinolytics in the peripartum period - concern for a hypercoagulable effect?

INTRODUCTION

Although antifibrinolytic agents are used to prevent and treat hemorrhage, there are concerns about a potential increased risk for peripartum venous thromboembolism. We sought to determine the impact of tranexamic acid and ɛ-aminocaproic acid on in vitro clotting properties in pregnancy.

METHODS

Blood samples were obtained from healthy pregnant, obese, and preeclamptic pregnant women (n = 10 in each group) prior to delivery as well as from healthy non-pregnant controls (n = 10). Maximum clot firmness (MCF) and clotting time (CT) were measured using rotation thromboelastometry in the presence of tranexamic acid (3, 30, or 300 μg/mL) or ɛ-aminocaproic acid (30, 300, or 3000 μg/mL). ANOVA and regression analyses were performed.

RESULTS

Mean whole blood MCF was significantly higher in healthy pregnant vs. non-pregnant women (66.5 vs. 57.5 mm, p < 0.001). Among healthy pregnant women, there was no significant difference between mean MCF (whole blood alone, and with increasing tranexamic acid doses = 66.5, 66.1, 66.4, 66.3 mm, respectively; p = 0.25) or mean CT (409, 412, 420, 424 sec; p = 0.30) after addition of tranexamic acid. Similar results were found using ɛ-aminocaproic acid. Preeclamptic women had a higher mean MCF after the addition of ɛ-aminocaproic acid and tranexamic acid (p = 0.05 and p = 0.04, respectively) compared to whole blood alone.

CONCLUSIONS

Pregnancy is a hypercoagulable state, as reflected by an increased MCF compared to non-pregnant women. Addition of antifibrinolytic therapy in vitro does not appear to increase MCF or CT for non-pregnant, pregnant, and obese women. Whether antifibrinolytics are safe in preeclampsia may require further study.

Effectiveness of tranexamic acid for reducing intraoperative bleeding in palatoplasties: A randomized clinical trial

BACKGROUND

Few data are available regarding blood loss during cleft palate surgery. This study assessed the effect of using tranexamic acid in the reduction of intraoperative bleeding.

METHODS

A double-blind, randomized clinical trial compared intraoperative bleeding and the incidence of oronasal fistulas after palatoplasties in a control group that was given placebo and an intervention group that was given 10 mg/kg tranexamic acid followed by a continuous infusion of 1 mg/kg/h of the same until the end of surgery. Patients who underwent primary palatoplasty with no known or suspected coagulation disorders at our institution during the study period were included in the study.

RESULTS

70 patients were allocated, 66 received the intervention. Blood loss was reduced by 11.9%, without statistical significance. The incidence of fistulas in the intervention and control groups was 12.9% and 18.75%, respectively. The reduction of 5.8% (CI 95%: 12%-23.8%) was not significant.

CONCLUSIONS

The reduction of intraoperative blood loss was lower than expected and not statistically significant; a larger sample is needed to confirm the observed reduction. The drug did not seem to have negative effects on flap viability.

Major liver resection, systemic fibrinolytic activity, and the impact of tranexamic acid

BACKGROUND

Hyperfibrinolysis may occur due to systemic inflammation or hepatic injury that occurs during liver resection. Tranexamic acid (TXA) is an antifibrinolytic agent that decreases bleeding in various settings, but has not been well studied in patients undergoing liver resection.

METHODS

In this prospective, phase II trial, 18 patients undergoing major liver resection were sequentially assigned to one of three cohorts: (i) Control (no TXA); (ii) TXA Dose I - 1 g bolus followed by 1 g infusion over 8 h; (iii) TXA Dose II - 1 g bolus followed by 10 mg/kg/hr until the end of surgery. Serial blood samples were collected for thromboelastography (TEG), coagulation components and TXA concentration.

RESULTS

No abnormalities in hemostatic function were identified on TEG. PAP complex levels increased to peak at 1106 μg/L (normal 0-512 μg/L) following parenchymal transection, then decreased to baseline by the morning following surgery. TXA reached stable, therapeutic concentrations early in both dosing regimens. There were no differences between patients based on TXA.

CONCLUSIONS

There is no thromboelastographic evidence of hyperfibrinolysis in patients undergoing major liver resection. TXA does not influence the change in systemic fibrinolysis; it may reduce bleeding through a different mechanism of action. Registered with ClinicalTrials.gov: NCT01651182.

Tranexamic acid prolongs survival after controlled hemorrhage in rats

BACKGROUND

The plasmin/plasminogen inhibitor tranexamic acid (TXA) is mainly used in elective surgeries with a higher blood loss to avoid uncontrolled bleeding. Recently, TXA has also been shown to reduce mortality in trauma patients. It is assumed that its beneficial effects are principally caused by its antifibrinolytic properties. We hypothesize that TXA also improves survival in a modified Wigger's model of hemorrhagic shock by a mechanism other than antifibrinolysis.

MATERIALS AND METHODS

Male Wistar rats were intermittently bled until the mean arterial blood pressure was dropped to 25-30 mm Hg (severe shock). After shock induction, the animals received either 0.14-0.15 mL TXA (30 mg/kg) i.v. or the equivalent volume of 0.9% NaCl given as bolus. Adjacent to the shock period, the rats were resuscitated with Ringer's solution within 30 min and observed for another 150 min unless the animals died earlier.

RESULTS

In the animals treated with TXA, survival was clearly prolonged and acid-base parameters showed some differences as compared to the animals receiving only NaCl. In the model used, coagulation slightly declined, but an increased fibrinolysis was not observed.

CONCLUSIONS

Since in the applied shock model fibrinolysis is negligible, we postulate that TXA is capable of providing protection against hemorrhagic shock independent from its antifibrinolytic properties.

Bleeding related to disturbed fibrinolysis

The components and reactions of the fibrinolysis system are well understood. The pathway has fewer reactants and interactions than coagulation, but the generation of a complete quantitative model is complicated by the need to work at the solid‐liquid interface of fibrin. Diagnostic tools to detect disease states due to malfunctions in the fibrinolysis pathway are also not so well developed as is the case with coagulation. However, there are clearly a number of inherited or acquired pathologies where hyperfibrinolysis is a serious, potentially life‐threatening problem and a number of antifibrinolytc drugs are available to treat hyperfibrinolysis. These topics will be covered in the following review.

Early tranexamic acid administration: A protective effect on gut barrier function following ischemia/reperfusion injury

BACKGROUND

The mucus barrier is a critical component of the gut barrier and may be disrupted by pancreatic enzymes following trauma/hemorrhagic shock (T/HS). Luminal strategies against pancreatic enzyme activation or contact with the intestine are protective of the mucus layer and gut barrier integrity following T/HS. There is increasing evidence the use of tranexamic acid (TA) attenuates inflammatory responses in cardiac surgery and is readily absorbed from the gut. We therefore postulated that systemic administration of TA would attenuate mucus degradation and gut barrier failure following T/HS. This was studied in an in vitro model.

METHODS

Confluent monolayers of HT29-MTX (mucus-producing clone) and Caco-2 cocultures were exposed to 90 minutes of hypoxia followed by reoxygenation (H/R), luminal trypsin (5 μM), or both treatment groups. In a subset of experiments, TA (40 μM or 150 μM) was added to the basal chamber (systemic side) of intestinal cell cultures immediately following the hypoxic period. Mucus barrier function was indexed by rheologic measurement of both mucus thickness and viscosity (G', dyne/cm) and oxidant stress. Intestinal cell barrier integrity was indexed by transepithelial electrical resistance, permeability to fluorescein isothiocyanate-dextran, and apoptosis by flow cytometry.

RESULTS

Exposure to both trypsin and H/R of Caco-2/HT29-MTX cocultures led to the most severe effect on mucus barrier function. Administration of TA immediately following hypoxia abrogated the effects noted on mucus barrier function. The epithelial barrier was also most severely impacted by both trypsin and H/R. Addition of TA after the hypoxic event was shown to be protective.

CONCLUSION

Intestinal mucus physiochemical properties and intestinal barrier function were most severely impacted by exposure to both trypsin (concentration related) and H/R. The "systemic" administration of TA immediately after the hypoxic period was protective and suggests an additional role for early administration of TA in trauma patients in shock.

A comparison of high-dose and low-dose tranexamic acid antifibrinolytic protocols for primary coronary artery bypass surgery

BACKGROUND AND AIMS

Tranexamic acid (TA) is used for prophylactic antifibrinolysis in coronary artery bypass surgeries to reduce bleeding. We evaluated the efficacy of two different doses of TA for prophylactic antifibrinolysis in patients undergoing primary coronary artery bypass grafting (CABG) surgery in this retrospective cohort study at a tertiary care referral centre.

METHODS

One-hundred eighty-four patients who underwent primary CABG with cardiopulmonary bypass (CPB) via sternotomy between January 2009 and June 2011 were evaluated. Pre-operative patient characteristics, intraoperative data, post-operative bleeding, transfusions, organ dysfunction and 30-day mortality were compared between high-dose TA (30 mg/kg loading dose followed by infusion of 15 mg/kg/h until the end of surgery along with 2 mg/kg priming dose in the bypass circuit) and low-dose TA (15 mg/kg loading dose followed by infusion of 6 mg/kg/h until the end of surgery along with 1 mg/kg priming dose in the bypass circuit) groups. Univariate comparative analysis of all categorical and continuous variables was performed between the two groups by appropriate statistical tests. Linear and logistic regression analyses were performed to control for the effect of confounding on the outcome variables.

RESULTS

Chest tube output, perioperative transfusion of blood products and incidence of re-exploration for bleeding did not differ significantly (P> 0.05) between groups. Post-operative complications and 30-day mortality were comparable between the groups. The presence of cardiogenic shock and increased pre-operative creatinine were found to be associated with increased chest tube output on the post-operative day 2 by multivariable linear regression model.

CONCLUSIONS

Low-dose TA protocol is as effective as high-dose protocol for antifibrinolysis in patients undergoing primary CABG with CPB.