Tranexamic acid administration after cardiac surgery: a prospective, randomized, double-blind, placebo-controlled study

The effect of tranexamic acid on myocardial injury in cardiac surgical patients: a systematic review and meta-analysis

Tranexamic acid (TXA) is one of the most commonly used antifibrinolytic agents for surgical patients. However, the effect of TXA on myocardial injury remains controversial. We systemically reviewed literature regarding the effectiveness of TXA on myocardial injury in patients who have undergone a cardiac surgery. We included all randomized controlled trials (RCTs) comparing TXA and control (saline) in cardiac surgical patients. Relevant studies were identified by a comprehensive electronic literature search from database inception to 15 August 2021. A standardized data extraction form was used to collect methodological and outcome variables from each eligible study. We conducted a meta-analysis to estimate the pooled effect size of TXA administration on myocardial injury. In total, eight RCTs were identified, with 292 patients in the TXA group, and 241 patients in saline or control group. The meta-analysis demonstrated that patients in the TXA group had lower levels of CK-MB and cTnI within 24 h postoperatively (CK-MB: P  = 0.005; cTnI: P  = 0.01), compared with the saline group. No significant difference was found with respect to AST level ( P  = 0.71) between TXA and saline groups within 24 h postoperatively. TXA administration was found to be associated with less myocardial injury among patients who have undergone cardiac surgery. High-quality randomized controlled trials are warranted to further examine the cardioprotective effects of TXA.

Reoperation for bleeding after cardiac surgery

BACKGROUND

Postoperative cardio-surgical haemostatic management is centre-specific and experience-based, which leads to a variability in patient care. This study aimed to identify which postoperative haemostatic interventions may reduce the need for reoperation after cardiac surgery in adults.

METHODS

A retrospective case-control study in a tertiary centre. Adult, elective, primary cardiac surgical patients were selected (n = 2098); cases (n = 42) were patients who underwent reoperation within 72 h after the initial surgery. Interventions administered to control surgical bleeding were compared for the need to re-operate using multiple logistic regression.

RESULTS

Rate of cardiac surgical reoperation was 2% in the study population. Three variables were found to be associated with cardiac reoperation: preoperative administration of fresh frozen plasma (OR 5.45, CI 2.34-12.35), cumulative volume of chest tube drainage and cumulative count of packed red blood cells transfusion on ICU (OR 1.98, CI 1.56-2.51).

CONCLUSION

No significant difference among specific types of postoperative haemostatic interventions was found between patients who needed reoperation and those who did not. Perioperative transfusion of fresh frozen plasma, postoperative transfusion of packed cells and cumulative volume of chest tube drainage were associated with reoperation after cardiac surgery. These variables could help predict the need for reoperation.

Effect of tranexamic acid on thrombotic events and seizures in bleeding patients: a systematic review and meta-analysis

BACKGROUND

Tranexamic acid (TXA) reduces surgical bleeding and reduces death from bleeding after trauma and childbirth. However, its effects on thrombotic events and seizures are less clear. We conducted a systematic review and meta-analysis to examine the safety of TXA in bleeding patients.

METHODS

For this systematic review and meta-analysis, we searched MEDLINE, EMBASE and the Cochrane Central Register of Controlled trials from inception until June 1, 2020. We included randomized trials comparing intravenous tranexamic acid and placebo or no intervention in bleeding patients. The primary outcomes were thrombotic events, venous thromboembolism, acute coronary syndrome, stroke and seizures. A meta-analysis was performed using a random effects model and meta-regression analysis was performed to evaluate how effects vary by dose. We assessed the certainty of evidence using the grading of recommendations, assessment, development and evaluations (GRADE) approach.

RESULTS

A total of 234 studies with 102,681 patients were included in the meta-analysis. In bleeding patients, there was no evidence that TXA increased the risk of thrombotic events (RR = 1.00 [95% CI 0.93-1.08]), seizures (1.18 [0.91-1.53]), venous thromboembolism (1.04 [0.92-1.17]), acute coronary syndrome (0.88 [0.78-1.00]) or stroke (1.12 [0.98-1.27]). In a dose-by-dose sensitivity analysis, seizures were increased in patients receiving more than 2 g/day of TXA (3.05 [1.01-9.20]). Meta-regression showed an increased risk of seizures with increased dose of TXA (p = 0.011).

CONCLUSION

Tranexamic acid did not appear to increase the risk of thrombotic events in bleeding patients. However, because there may be dose-dependent increase in the risk of seizures, very high doses should be avoided.

Tranexamic acid after cardiopulmonary bypass does not increase risk of postoperative seizures: a retrospective study

OBJECTIVE

To evaluate the effects of administering tranexamic acid (TXA) after cardiopulmonary bypass, instead of after anesthesia induction, on postoperative seizures and blood transfusion requirements.

METHODS

Adult patients who underwent valve surgery and/or coronary artery bypass grafting at West China Hospital between July 1, 2011 and December 31, 2016 were retrospectively analyzed. Patients either received TXA after bypass (n = 2062) or not (n = 4236). Logistic regression and propensity score matching analysis were performed to assess effects of TXA on postoperative seizures and blood product requirements in hospital.

RESULTS

Among 6298 patients, seizures occurred in 2.4% (102/4236) in the no-TXA group and 2.7% (56/2062) in the TXA group (P = 0.46). The number of patients receiving any blood products was greater in the no-TXA group (57.3%, 2428/4236) than in the TXA group (53.1%, 1095/2062) (P < 0.01), and the volume of blood products was also greater in the no-TXA group (1.5 vs. 1.0 units, P < 0.01). TXA was not associated with increased incidence of postoperative seizures (adjusted OR 1.16, 95% CI 0.83-1.62) but was associated with lower incidence of a requirement for blood products (adjusted OR 0.82, 95% CI 0.73-0.92). Similar results were obtained after patients from the two groups were matched based on propensity scoring. TXA was associated with reduced requirements for fresh frozen plasma, platelets and cryoprecipitate, but not red blood cells.

CONCLUSIONS

Administering TXA after bypass may reduce requirements for blood products without increasing risk of seizures following cardiac surgery.

Tranexamic acid in patients with complex stones undergoing percutaneous nephrolithotomy: a randomised, double-blinded, placebo-controlled trial

OBJECTIVES

To assess the efficacy and safety of single-dose tranexamic acid on the blood transfusion rate and outcomes of patients with complex kidney stones undergoing percutaneous nephrolithotomy (PCNL).

PATIENTS AND METHODS

In a randomised, double-blinded, placebo-controlled trial, 192 patients with complex kidney stone (Guy's Stone Scores III-IV) were prospectively enrolled and randomised (1:1 ratio) to receive either one dose of tranexamic acid (1 g) or a placebo at the time of anaesthetic induction for PCNL. The primary outcome measure was the occurrence rate of perioperative blood transfusion. The secondary outcome measures included blood loss, operative time, stone-free rate (SFR), and complications. ClinicalTrials.gov identifier: NCT02966236.

RESULTS

The overall risk of receiving a blood transfusion was reduced in the tranexamic acid group (2.2% vs 10.4%; relative risk, 0.21, 95% confidence interval [CI] 0.03-0.76, P = 0.033; number-needed-to-treat: 12). Patients randomised to the tranexamic acid group had a higher immediate and 3-month SFR compared with those in the placebo group (29% vs 14.7%, odds ratio [OR] 2.37, 95% CI 1.15-4.87, P = 0.019, and 46.2% vs 28.1%, OR 2.20, 95% CI 1.20-4.02, P = 0.011, respectively). Faster haemoglobin recovery occurred in patients in the tranexamic acid group (mean, 21.3 days; P = 0.001). No statistical differences were found in operative time and complications between groups.

CONCLUSIONS

Tranexamic acid administration is safe and reduces the need for blood transfusion by five-times in patients with complex kidney stones undergoing PCNL. Moreover, tranexamic acid may contribute to better stone clearance rate and faster haemoglobin recovery without increasing complications. A single dose of tranexamic acid at the time of anaesthetic induction could be considered standard clinical practice for patients with complex kidney stones undergoing PCNL.

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

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.

Comparison of Blood-Conserving and Allogenic Transfusion-Sparing Effects of Antifibrinolytics in Scoliosis Correction Surgery

Background:

Intraoperative antifibrinolytic drug administration is a safe and effective method of reducing blood loss and allogenic transfusions in patients undergoing spine deformity correction.

Aim:

This study aimed to compare the effectiveness of two antifibrinolytic drugs tranexamic acid (TXA) and epsilon amino caproic acid (EACA) in reducing peri-operative blood loss and transfusion requirements against a placebo control in patients with idiopathic scoliosis undergoing correction surgery.

Setting and Design:

This is a prospective, randomized, double-blinded, controlled comparative study.

Methodology:

Patients in TXA group received 50 mg.kg⁻¹ bolus and 10 mg.kg⁻¹.h⁻¹ infusion as against 100 mg.kg⁻¹ and 10 mg.kg⁻¹.h⁻¹ infusion in EACA group. The placebo group had saline bolus and infusion. Parameters observed included baseline demographic and deformity data, duration of surgery, total peri-operative blood loss, and allogenic packed red cell transfusion requirements.

Statistical Analysis:

Mean and standard deviation were used to represent the quantitative continuous data, and percentage was used to represent categorical data. The Student's t-test and ANOVA were used to compare means between groups. Bonferroni's multiple comparison test was used to find out the association between categorical variables.

Results:

A total of 36 patients were enrolled with 12 patients in each group. Peri-operative blood loss was 50.1% lower in patients receiving TXA and 17.7% lower in patients receiving EACA compared with the placebo group. The volume of total packed red cell transfusion was 66.7% lower in patients receiving TXA and 45.6% lower in patients receiving EACA compared with placebo.

Conclusion:

TXA was more effective in reducing total peri-operative blood loss and allogenic transfusion requirement in idiopathic scoliosis correction surgery compared to EACA.

Exclusion criteria and adverse events in perioperative trials of tranexamic acid: a systematic review and meta-analysis

BACKGROUND

Tranexamic acid (TXA) is an inexpensive therapy effective at minimizing perioperative blood loss and transfusion. However, it remains underutilized due to safety concerns. To date, no evidence-based guidelines exist identifying which patients should not receive TXA therapy. This study determined patient groups for whom safety information regarding TXA is lacking due to common exclusion from perioperative TXA trials.

STUDY DESIGN AND METHODS

A systematic review searching the databases Medline, EMBASE, CENTRAL, and Clinicaltrials.gov was performed. Randomized controlled trials (RCTs) administering systemic TXA perioperatively to elective or emergent surgery patients were eligible. Our primary outcome was to describe exclusion criteria of RCTs, and the secondary outcome was TXA safety. A descriptive synthesis of exclusion criteria was performed, and TXA safety was assessed by meta-analysis.

RESULTS

A total of 268 eligible RCTs were included. Meta-analysis showed that systemic TXA did not increase risk of adverse events compared to placebo or no intervention (relative risk, 1.05; 95% confidence interval, 0.99-1.12). Patient groups commonly excluded from perioperative TXA trials, and thus potentially lacking TXA safety data, were those with major comorbidities, a history of thromboembolism, medication use affecting coagulation, TXA allergy, and coagulopathy. Exclusion of patients with major comorbidities may not be necessary; we showed that the risk of adverse events was similar in studies that excluded patients with major comorbidities and those that did not.

CONCLUSION

Sufficient evidence exists to develop perioperative guidelines for TXA use in many populations. Further studies evaluating perioperative TXA use in patients with a history of thromboembolism are warranted.

Korean clinical practice guideline for perioperative red blood cell transfusion from Korean Society of Anesthesiologists

Background

Considering the functional role of red blood cells (RBC) in maintaining oxygen supply to tissues, RBC transfusion can be a life-saving intervention in situations of severe bleeding or anemia. RBC transfusion is often inevitable to address intraoperative massive bleeding; it is a key component in safe perioperative patient management. Unlike general medical resources, packed RBCs (pRBCs) have limited availability because their supply relies entirely on voluntary donations. Additionally, excessive utilization of pRBCs may aggravate prognosis or increase the risk of developing infectious diseases. Appropriate perioperative RBC transfusion is, therefore, crucial for the management of patient safety and medical resource conservation. These concerns motivated us to develop the present clinical practice guideline for evidence-based efficient and safe perioperative RBC transfusion management considering the current clinical landscape.

Methods

This guideline was obtained after the revision and refinement of exemplary clinical practice guidelines developed in advanced countries. This was followed by rigorous evidence-based reassessment considering the healthcare environment of the country.

Results

This guideline covers all important aspects of perioperative RBC transfusion, such as preoperative anemia management, appropriate RBC storage period, and leukoreduction (removal of white blood cells using filters), reversal of perioperative bleeding tendency, strategies for perioperative RBC transfusion, appropriate blood management protocols, efforts to reduce blood transfusion requirements, and patient monitoring during a perioperative transfusion.

Conclusions

This guideline will aid decisions related to RBC transfusion in healthcare settings and minimize patient risk associated with unnecessary pRBC transfusion.

Does topical tranexamic acid reduce postcoronary artery bypass graft bleeding?

Background:

Postoperative bleeding is a common problem in cardiac surgery. We tried to evaluate the effect of topical tranexamic acid (TA) on reducing postoperative bleeding of patients undergoing on-pump coronary artery bypass graft (CABG) surgery.

Materials and Methods:

One hundred and twenty-six isolated primary CABG patients were included in this clinical trial. They were divided blindly into two groups; Group 1, patients receiving 1 g TA diluted in 100 ml normal saline poured into mediastinal cavity before closing the chest and Group 2, patients receiving 100 ml normal saline at the end of operation. First 24 and 48 h chest tube drainage, hemoglobin decrease and packed RBC transfusion needs were compared.

Results:

Both groups were the same in baseline characteristics including gender, age, body mass index, ejection fraction, clamp time, bypass time, and operation length. During the first 24 h postoperatively, mean chest tube drainage in intervention group was 567 ml compared to 564 ml in control group (P = 0.89). Mean total chest tube drainage was 780 ml in intervention group and 715 ml in control group (P = 0.27). There was no significant difference in both mean hemoglobin decrease (P = 0.26) and packed RBC transfusion (P = 0.7). Topical application of 1 g TA diluted in 100 ml normal saline does not reduce postoperative bleeding of isolated on-pump CABG surgery.

Conclusion:

We do not recommend topical usage of 1 g TA diluted in 100 ml normal saline for decreasing blood loss in on-pump CABG patients.

Intraoperative tranexamic acid is associated with postoperative stroke in patients undergoing cardiac surgery

BACKGROUND

Stroke is a devastating and potentially preventable complication of cardiac surgery. Tranexamic acid (TXA) is a commonly antifibrinolytic agent in cardiac surgeries with cardiopulmonary bypass (CPB), however, there is concern that it might increase incidence of stroke after cardiac surgery. In this retrospective study, we investigated whether TXA usage could increase postoperative stroke in cardiac surgery.

METHODS

A retrospective study was conducted from January 1, 2010, to December 31, 2015, in 2,016 patients undergoing cardiac surgery, 664 patients received intravenous TXA infusion and 1,352 patients did not receive any antifibrinolytic agent. Univariate and propensity-weighted multivariate regression analysis were applied for data analysis.

RESULTS

Intraoperative TXA administration was associated with postoperative stroke (1.7% vs. 0.5%; adjusted OR, 4.11; 95% CI, 1.33 to 12.71; p = 0.014) and coma (adjusted OR, 2.77; 95% CI, 1.06 to 7.26; p = 0.038) in cardiac surgery. As subtype analysis was performed, TXA administration was still associated with postoperative stroke (1.7% vs. 0.3%; adjusted OR, 5.78; 95% CI, 1.34 to 27.89; p = 0.018) in patients undergoing valve surgery or multi-valve surgery only, but was not associated with postoperative stroke (1.7% vs. 1.3%; adjusted OR, 5.21; 95% CI, 0.27 to 101.17; p = 0.276) in patients undergoing CABG surgery only. However, TXA administration was not associated with postoperative mortality (adjusted OR, 1.31; 95% CI, 0.56 to 3.71; p = 0.451), seizure (adjusted OR, 1.13; 95% CI, 0.42 to 3.04; p = 0.816), continuous renal replacement therapy (adjusted OR, 1.36; 95% CI, 0.56 to 3.28; p = 0.495) and resternotomy for postoperative bleeding (adjusted OR, 1.55; 95% CI, 0.55 to 4.30; p = 0.405). No difference was found in postoperative ventilation time (adjusted B, -1.45; SE, 2.33; p = 0.535), length of intensive care unit stay (adjusted B, -0.12; SE, 0.25; p = 0.633) and length of hospital stay (adjusted B, 0.48; SE, 0.58; p = 0.408).

CONCLUSIONS

Based on the 5-year experience of TXA administration in cardiac surgery with CPB, we found that postoperative stroke was associated with intraoperative TXA administration in patients undergoing cardiac surgery, especially in those undergoing valve surgeries only. This study may suggest that TXA should be administrated according to clear indications after evaluating the bleeding risk in patients undergoing cardiac surgery, especially in those with high stroke risk.

Association between CK-MB Area Under the Curve and Tranexamic Acid Utilization in Patients Undergoing Coronary Artery Bypass Surgery

Myonecrosis after coronary artery bypass graft (CABG) surgery is associated with excess mortality. Tranexamic acid (TA), an anti-fibrinolytic agent, has been shown to reduce peri-operative blood loss without increasing the risk of myocardial infarction (MI); however, no large study has examined the association between TA treatment and post-CABG myonecrosis. In the MC-1 to Eliminate Necrosis and Damage in Coronary Artery Bypass Graft Surgery II trial, inverse probability weighting of the propensity to receive TA was used to test for differences among the 656 patients receiving and 770 patients not receiving TA. The primary outcome was creatine kinase MB (CK-MB) area under the curve (AUC) through 24 h. The secondary outcome was 30-day cardiovascular death or MI. Patients who received TA were more frequently female, had a previous MI, heart failure, low molecular weight heparin therapy, on-pump CABG, valvular surgery, and saphenous vein or radial grafts. The median 24-h CK-MB AUC was higher in TA-treated patients [301.9 (IQR 196.7-495.6) vs 253.5 (153.4-432.5) ng h/mL, p < 0.001]. No differences in the 30-day incidence of cardiovascular death or MI were observed (8.7 vs 8.3%, adjusted OR 0.99; 95% CI 0.67-1.45, p = 0.948). In patients undergoing CABG, TA use was associated with a higher risk of myonecrosis; however, no differences were observed in death or MI. Future larger studies should be directed at examining the pathophysiology of TA myonecrosis, and its association with subsequent clinical outcomes.

Blood Conservation Strategies in Cardiac Surgery

Perioperative bleeding in cardiac surgery is related to both surgical trauma of blood vessels and defects in the hemostatic mechanism caused, in part, by cardiopulmonary bypass. Blood transfusion therefore remains a significant risk of cardiac surgery with important health and economic consequences. Blood conservation strategies for cardiac surgery have advanced over the years and the following discussion will focus on the current practices at Toronto General Hospital.

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.

Practice guidelines for perioperative blood management: an updated report by the American Society of Anesthesiologists Task Force on Perioperative Blood Management*

The American Society of Anesthesiologists Committee on Standards and Practice Parameters and the Task Force on Perioperative Blood Management presents an updated report of the Practice Guidelines for Perioperative Blood Management.

Supplemental Digital Content is available in the text.

Low dose tranexamic acid effect on post-coronary artery bypass grafting bleeding

Objective

This study investigated the effects of low-dose tranexamic acid on post-coronary artery bypass surgery bleeding .

Background

Diffuse microvascular bleeding is still a common problem after cardiac procedures. This study was designed to evaluate the hemostatic effects of low-dose tranexamic acid in on-pump coronary artery bypass graft surgery.

Methods

In this prospective randomized placebo-controlled study, 150 patients who were candidates for coronary artery bypass were enrolled and randomly assigned to 1 of 2 groups (tranexamic acid or placebo). Total drainage volume and the need for transfusion as well as surgical complications were recorded and compared in the 2 groups.

Results

There was significantly less mediastinal chest tube drainage up to 48 h in the tranexamic acid group (432 ± 210 mL) compared to the placebo group (649 ± 235 mL, p = 0.006). In the placebo group, 43 (58%) patients were given allogeneic blood during hospital stay compared to 22 (25%) in the tranexamic acid group ( p < 0.001). No significant difference in postoperative complications was seen.

Conclusion

The use of low-dose tranexamic acid can significantly reduce blood loss and need for transfusion, with no increase in complications.

Hyperfibrinolysis elicited via thromboelastography predicts mortality in trauma

BACKGROUND

The acute coagulopathy of trauma has been identified as a critical determinant of outcomes. Antifibrinolytic agents have recently been demonstrated to improve outcomes. This prospective study was designed to assess coagulopathy in trauma patients using thromboelastography.

STUDY DESIGN

Trauma patients meeting our institution's highest tier of trauma team activation criteria were prospectively enrolled during a 5-month period ending April 1, 2011. Thromboelastography was performed at admission, +1 hour, +2 hours, and +6 hours using citrated blood. Hyperfibrinolysis was defined as estimated percent lysis ≥15%. Patients were followed throughout their hospital course to collect clinical data and outcomes.

RESULTS

One hundred and eighteen patients were enrolled (77.1% were male, 51.7% had penetrating trauma, 7.6% had systolic blood pressure <90 mmHg, 47.5% had Injury Severity Score >16, and 23.7% had Glasgow Coma Scale score ≤8). Hyperfibrinolysis was present in 13 patients (11.0%), with a mean time to detection of 13 minutes (range 2 to 60 minutes). By the 6-hour sampling, 8 (61.5%) of the hyperfibrinolytic patients had expired from hemorrhage. Survivors at this point demonstrated correction of coagulopathy, however, 12 patients (92.3%) ultimately expired (75% hemorrhage, 25% head injury). On stepwise logistic regression, hyperfibrinolysis was a strong predictor of early (24 hours) mortality (odds ratio = 25.0; 95% CI, 2.8-221.4; p = 0.004), predicting 53% of early deaths. Compared with patients without hyperfibrinolysis, patients with hyperfibrinolysis had a greater need for massive transfusion (76.9% vs 8.7%; adjusted odds ratio = 19.1; 95% CI, 3.6-101.3; p < 0.001) and had a greater early mortality (69.2% vs 1.9%; adjusted odds ratio = 55.8; 95% CI, 7.2-432.3; p < 0.001) and in-hospital mortality (92.3% vs 9.5%; adjusted odds ratio = 55.5; 95% CI, 4.8-649.7; p = 0.001).

CONCLUSIONS

In this prospective analysis, hyperfibrinolysis on thromboelastography developed in approximately 10% of patients and was considerably more likely to require massive transfusion. Hyperfibrinolysis was a strong independent predictor of mortality. Additional evaluation of the role of thromboelastography-directed antifibrinolytic therapies is warranted.

Tranexamic acid: a review of its use in the treatment of hyperfibrinolysis

Tranexamic acid, a synthetic derivative of the amino acid lysine, is an antifibrinolytic agent that acts by binding to plasminogen and blocking the interaction of plasmin(ogen) with fibrin, thereby preventing dissolution of the fibrin clot. Tranexamic acid (Transamin®) is indicated in Japan for use in certain conditions with abnormal bleeding or bleeding tendencies in which local or systemic hyperfibrinolysis is considered to be involved. This article reviews the efficacy and tolerability of tranexamic acid in conditions amenable to antifibrinolytic therapy and briefly overviews the pharmacological properties of the drug. In large, randomized controlled trials, tranexamic acid generally significantly reduced perioperative blood loss compared with placebo in a variety of surgical procedures, including cardiac surgery with or without cardiopulmonary bypass, total hip and knee replacement and prostatectomy. In many instances, tranexamic acid also reduced transfusion requirements associated with surgery. It also reduced blood loss in gynaecological bleeding disorders, such as heavy menstrual bleeding, postpartum haemorrhage and bleeding irregularities caused by contraceptive implants. Tranexamic acid significantly reduced all-cause mortality and death due to bleeding in trauma patients with significant bleeding, particularly when administered early after injury. It was also effective in traumatic hyphaema, gastrointestinal bleeding and hereditary angioneurotic oedema. While it reduces rebleeding in subarachnoid haemorrhage, it may increase ischaemic complications. Pharmacoeconomic analyses predicted that tranexamic acid use in surgery and trauma would be very cost effective and potentially life saving. In direct comparisons with other marketed agents, tranexamic acid was at least as effective as ε-aminocaproic acid and more effective than desmopressin in surgical procedures. It was more effective than desmopressin, etamsylate, flurbiprofen, mefenamic acid and norethisterone, but less effective than the levonorgestrel-releasing intra-uterine device in heavy menstrual bleeding and was as effective as prednisolone in traumatic hyphaema. Tranexamic acid was generally well tolerated. Most adverse events in clinical trials were of mild or moderate severity; severe or serious events were rare. Therefore, while high-quality published evidence is limited for some approved indications, tranexamic acid is an effective and well tolerated antifibrinolytic agent.

Effect of tranexamic acid on surgical bleeding: systematic review and cumulative meta-analysis

OBJECTIVE

To assess the effect of tranexamic acid on blood transfusion, thromboembolic events, and mortality in surgical patients.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Cochrane central register of controlled trials, Medline, and Embase, from inception to September 2011, the World Health Organization International Clinical Trials Registry Platform, and the reference lists of relevant articles.

STUDY SELECTION

Randomised controlled trials comparing tranexamic acid with no tranexamic acid or placebo in surgical patients. Outcome measures of interest were the number of patients receiving a blood transfusion; the number of patients with a thromboembolic event (myocardial infarction, stroke, deep vein thrombosis, and pulmonary embolism); and the number of deaths. Trials were included irrespective of language or publication status.

RESULTS

129 trials, totalling 10,488 patients, carried out between 1972 and 2011 were included. Tranexamic acid reduced the probability of receiving a blood transfusion by a third (risk ratio 0.62, 95% confidence interval 0.58 to 0.65; P<0.001). This effect remained when the analysis was restricted to trials using adequate allocation concealment (0.68, 0.62 to 0.74; P<0.001). The effect of tranexamic acid on myocardial infarction (0.68, 0.43 to 1.09; P = 0.11), stroke (1.14, 0.65 to 2.00; P = 0.65), deep vein thrombosis (0.86, 0.53 to 1.39; P = 0.54), and pulmonary embolism (0.61, 0.25 to 1.47; P=0.27) was uncertain. Fewer deaths occurred in the tranexamic acid group (0.61, 0.38 to 0.98; P = 0.04), although when the analysis was restricted to trials using adequate concealment there was considerable uncertainty (0.67, 0.33 to 1.34; P = 0.25). Cumulative meta-analysis showed that reliable evidence that tranexamic acid reduces the need for transfusion has been available for over 10 years.

CONCLUSIONS

Strong evidence that tranexamic acid reduces blood transfusion in surgery has been available for many years. Further trials on the effect of tranexamic acid on blood transfusion are unlikely to add useful new information. However, the effect of tranexamic acid on thromboembolic events and mortality remains uncertain. Surgical patients should be made aware of this evidence so that they can make an informed choice.

Tranexamic acid and primary coronary artery bypass surgery: a prospective study

Tranexamic acid was used to reduce postoperative drainage and allogenic blood transfusion requirements in patients undergoing on-pump primary coronary bypass surgery. Over 12 months, 222 patients participated in this prospective, randomized, placebo-controlled, double-blind study conducted at a tertiary center. Half of the patients were randomly allocated to receive tranexamic acid as a bolus (10 mg x kg(-1)) prior to sternotomy, followed by an infusion (1 mg x kg(-1) x hr(-1)) up to the time of starting of protamine. The other 111 patients received a saline bolus and infusion. Postoperative drainage and transfusion requirements were measured in all patients. Markers of graft patency, hemostasis, hemodynamic stability, and fibrinolysis were evaluated. Chest closure time, renal function parameters, allergic reactions, incidence of stroke, re-exploration, and hospital mortality were also noted. Postoperative drainage was significantly less and blood conservation considerably better when tranexamic acid was used. Post-bypass hemostasis was achieved faster, fibrinolysis was less, and there was no evidence of increased incidence of graft occlusion in the group given tranexamic acid.

Meta-analysis comparing the effectiveness and adverse outcomes of antifibrinolytic agents in cardiac surgery

BACKGROUND

Since the 1980s, antifibrinolytic therapies have assisted surgical teams in reducing the amount of blood loss. To date, however, serious questions remain regarding the safety and effectiveness of these agents.

METHODS AND RESULTS

We conducted a meta-analysis to compare aprotinin, epsilon-aminocaproic acid, and tranexamic acid with placebo and head to head on 8 clinical outcomes from 138 trials. Published randomized controlled trial data were collected from OVID/PubMed. Outcomes included total blood loss, transfusion of packed red blood cells, reexploration, mortality, stroke, myocardial infarction, dialysis-dependent renal failure, and renal dysfunction (0.5-mg/dL increase in creatinine from baseline). All agents were effective in significantly reducing blood loss by 226 to 348 mL and the proportion of patients transfused with packed red blood cells over placebo. Only high-dose aprotinin reduced the rate of reexploration (relative risk, 0.49; 95% CI, 0.33 to 0.73). There were no significant risks or benefits for any agent for mortality, stroke, myocardial infarction, or renal failure. However, high-dose aprotinin significantly increased the risk of renal dysfunction (relative risk, 1.47; 95% CI, 1.12 to 1.94), 12.9% versus 8.4%. Compared head to head, high-dose aprotinin demonstrated significant reduction in total blood loss over epsilon-aminocaproic acid (-184 mL; 95% CI, -256 to -112) and tranexamic acid (-195 mL; 95% CI, -286 to -105). There were no significant differences among any agent when compared head to head on other outcomes.

CONCLUSIONS

All antifibrinolytic agents were effective in reducing blood loss and transfusion. There were no significant risks or benefits for mortality, stroke, myocardial infarction, or renal failure. However, high-dose aprotinin was associated with a statistically significant increased risk of renal dysfunction.

Tranexamic acid does not correct the haemostatic impairment caused by hydroxyethyl starch (200 kDa/0.5) after cardiac surgery

We investigated the effect of intravenous tranexamic acid on hydroxyethyl starch (HES)-induced clot strength impairment after cardiac surgery. Patients were randomized to receive either 1 g tranexamic acid or the same volume of 0.9% saline after administration of 15 ml/kg of 6% HES (molecular weight, 200 kDa; degree of substitution, 0.5) in the immediate postoperative period. Modified thromboelastometry (ROTEM) using different activators [intrinsic ROTEM (InTEM), extrinsic ROTEM (ExTEM), fibrinogen ROTEM (FibTEM)] was carried out to evaluate clot formation and lysis. The clot formation time was prolonged, and the maximum clot firmness (MCF) and shear elastic modulus [G = 5000 x MCF / (100-MCF), dynes/cm(2)] decreased (all activators of ROTEM) after completion of HES (P < 0.001, two-factor analysis of variance). These abnormalities in blood coagulation persisted despite tranexamic acid. Maximal lysis (FibTEM), indicative of fibrinolytic activity, was increased after HES but no effect of tranexamic acid was observed. The cumulative chest tube drainage until the first postoperative morning was not different between the groups (1008 +/- 251 and 1081 +/- 654 ml, P = 0.698, respectively). We conclude that after cardiopulmonary bypass, HES-induced impairment in clot formation and strength, or increased fibrinolytic capacity, is not reversed by the administration of tranexamic acid.

Perioperative Management of a Heterozygous Carrier of Glanzmann’s Thrombasthenia Submitted to Coronary Artery Bypass Grafting With Cardiopulmonary Bypass

Glanzmann's thrombasthenia is a congenital hemorrhagic disorder transmitted as an autosomal recessive trait and characterized by altered production and/or assembly of the platelet membrane glycoprotein IIb/IIIa receptor. We describe the perioperative management of a heterozygous carrier of Glanzmann's thrombasthenia submitted to cardiac surgery with cardiopulmonary bypass and the case was complicated by early excessive postoperative bleeding.

Comparison of Textilinin-1 with Aprotinin as Serine Protease Inhibitors and as Antifibrinolytic Agents

Textilinin-1 (Q8008) was isolated from the venom of the Pseudonaja textilis and has a 47% sequence identity to the antihaemorrhagic therapeutic agent aprotinin. When equimolar concentrations of enzyme and aprotinin were pre-incubated, plasmin was inhibited 100%, plasma kallikrein 58%, and tissue kallikrein 99%. Under the same conditions, textilinin-1 inhibited plasmin 98%, plasma kallikrein 16% and tissue kallikrein 17%. Whole blood clot lysis was inhibited strongly by both aprotinin and textilinin-1, as shown by thrombelastography. At 2 microM inhibitor lysis initiated by t-PA was greater than 99% inhibited by aprotinin (LY60 = 0.4 +/- 0.1) whereas textilinin-1, inhibited lysis by 91% (LY60 = 8.9 +/- 0.7). The same trend was found with the lysis of euglobulin fractions. From these data textilinin-1 appears to be a more specific plasmin inhibitor than aprotinin but aprotinin inhibits clot lysis to a greater extent.

A randomized, double-blind, and placebo-controlled study with tranexamic acid of bleeding and fibrinolytic activity after primary coronary artery bypass grafting

Cardiopulmonary bypass is frequently associated with excessive blood loss. Platelet dysfunction is the main cause of non-surgical bleeding after open-heart surgery. We randomized 65 patients in a double-blind fashion to receive tranexamic acid or placebo in order to determine whether antifibrinolytic therapy reduces chest tube drainage. The tranexamic acid group received an intravenous loading dose of 10 mg/kg, before the skin incision, followed by a continuous infusion of 1 mg kg(-1) h(-1) for 5 h. The placebo group received a bolus of normal saline solution and continuous infusion of normal saline for 5 h. Postoperative bleeding and fibrinolytic activity were assessed. Hematologic data, convulsive seizures, allogeneic transfusion, occurrence of myocardial infarction, mortality, allergic reactions, postoperative renal insufficiency, and reopening rate were also evaluated. The placebo group had a greater postoperative blood loss (median (25th to 75th percentile) 12 h after surgery (540 (350-750) vs 300 (250-455) mL, P = 0.001). The placebo group also had greater blood loss 24 h after surgery (800 (520-1050) vs 500 (415-725) mL, P = 0.008). There was a significant increase in plasma D-dimer levels after coronary artery bypass grafting only in patients of the placebo group, whereas no significant changes were observed in the group treated with tranexamic acid. The D-dimer levels were 1057 (1025-1100) microg/L in the placebo group and 520 (435-837) microg/L in the tranexamic acid group (P = 0.01). We conclude that tranexamic acid effectively reduces postoperative bleeding and fibrinolysis in patients undergoing first-time coronary artery bypass grafting compared to placebo.

Beneficial effect of acute normovolemic hemodilution in cardiovascular surgery

OBJECTIVE

The efficacy of acute normovolemic hemodilution (ANH) in avoiding homologous blood transfusion (HBT) during cardiovascular surgery remains controversial. Our objective was to evaluate the impact of ANH on blood transfusion requirements during open cardiovascular surgery using cardiopulmonary bypass (CPB).

METHODS

We retrospectively reviewed 243 patients who had undergone open cardiac or thoracic aortic surgery using CPB between September 2001 and July 2003 in our department. ANH was performed when the hematocrit was over 35% and the patient was hemodynamically stable. Risk factors were selected in accordance with the Japanese Adult Cardiovascular Surgery Database and analyzed to determine their effect on perioperative HBT requirement.

RESULTS

Of the 243 patients, 64 (26%) underwent preoperative autologous blood donation and 62 (26%) ANH. HBT was required in 62% of patients (150/243) overall, in 32% (20/62) of ANH patients, and in 76% (130/171) of non-ANH patients. Multivariate stepwise logistic regression analysis revealed that preoperative or pre-donation hemoglobin value (p < 0.001), duration of surgery (p = 0.001), intraoperative minimum rectal temperature (p = 0.001), age (p = 0.002), need for emergency surgery (p = 0.003), amount of ANH (p = 0.018), blood loss (p = 0.033) and amount of preoperative autologous blood donation (p = 0.042) were independent predictors of the need for perioperative HBT.

CONCLUSIONS

Our data showed that open cardiovascular surgery using CPB continues to pose a high risk of HBT, but that ANH is an effective means of reducing this risk in those patients undergoing these operations.

Perioperative systemic haemostatic agents

Skilful surgery combined with blood-saving methods and careful management of blood coagulation will all help reduce unnecessary blood loss and transfusion requirements. Excessive surgical bleeding causes hypovolaemia, haemodynamic instability, anaemia and reduced oxygen delivery to tissues, with a subsequent increase in postoperative morbidity and mortality. The role of anaesthetists in managing surgical blood loss has increased greatly in the last decade. Position of the patient during surgery and the provision of a hypotensive anaesthetic regimen were once considered the most important contributions of the anaesthetist to decreasing blood loss. Now, several pharmacological haemostatic agents are being used by anaesthetists as blood-saving agents. After a brief discussion of the physiology of haemostasis, this article will review the evidence for the role of such agents in reducing perioperative blood loss and transfusion requirements.

Effects of tranexamic acid on postoperative bleeding and related hematochemical variables in coronary surgery: Comparison between on-pump and off-pump techniques

OBJECTIVES

Bleeding and inflammation are major complications of extracorporeal circulation. Off-pump coronary artery bypass grafting may reduce the rate of complications, but it can only be applied in selected cases. Pilot studies have shown a potential benefit from the use of antifibrinolytic drugs, but efficacy in randomized double-blind studies evaluating off- and on-pump coronary artery bypass grafting has not been proved.

METHODS

We enrolled 102 patients scheduled for on-pump (n = 51) or off-pump (n = 51) coronary artery bypass grafting. Patients were separately double-blind randomly assigned to treatment with tranexamic acid (1 g as 20-minute bolus before skin incision, followed by continuous infusion of 400 mg/h, with 500 mg added to priming in patients undergoing on-pump coronary artery bypass grafting) or placebo (saline solution of equivalent volume). Bleeding in the first 24 postoperative hours was the primary outcome. Requirement for allogeneic transfusions, thrombotic complications, outcomes, and monitoring of coagulation, fibrinolysis, and inflammation were also recorded.

RESULTS

Tranexamic acid reduced total postoperative bleeding by 43% in patients undergoing on-pump coronary artery bypass grafting and by 27% in those undergoing off-pump coronary artery bypass grafting (P <.0001), with 80% reduction in bleeding exceeding 600 mL (P <.001), 58% reduction in the requirement for all allogeneic transfusions (P =.07), and no apparent effect on thrombotic complications or outcome. This was associated with a reduction in plasma D-dimer levels (P <.0001), to a greater degree in patients undergoing on-pump coronary artery bypass grafting (P <.0001), and interleukin 6 levels (P <.0001), to a greater degree in patients undergoing off-pump coronary artery bypass grafting (P <.001).

CONCLUSIONS

By affecting fibrinolysis, tranexamic acid significantly reduces bleeding both in off- and on-pump coronary artery bypass grafting and may modulate inflammation in these surgical settings.

Intraoperative Moderate Acute Normovolemic Hemodilution Associated with a Comprehensive Blood-Sparing Protocol in Off-Pump Coronary Surgery

We evaluated the blood-sparing effects of intraoperative moderate acute normovolemic hemodilution (ANH) combined with intraoperative tranexamic acid treatment and shed blood reinfusion in patients undergoing off-pump coronary artery bypass (OPCAB). One-hundred consecutive OPCAB patients (baseline hematocrit >34%) were prospectively randomized to tranexamic acid treatment (control group; 50 patients) or to tranexamic acid treatment plus normovolemic (1:1 replacement with colloids) withdrawal of 17% +/- 2% of the circulating blood volume (ANH group; 50 patients). All patients had shed blood reinfused with intraoperative bleeding in excess of 250 mL. The requirement for allogeneic transfusions, based on strict a priori defined criteria, was the primary end point of the study. Hematochemical evaluations, bleeding, major complications, and other outcomes were also recorded. Demographics, baseline hematochemical data, and operative characteristics were similar in the two groups. Patients in the ANH group had a median of 850 mL of blood withdrawn and showed a lower intraoperative minimum hematocrit (31% vs 37%; P < 0.0001). Two patients in the ANH group versus 10 patients in the control group (odds ratio, 0.17; 95% confidence interval, 0.03-0.89; P = 0.028) required transfusion of a significantly smaller number of packed red blood cell units (5 vs 24; P < 0.001). Postoperative hematochemical variables, bleeding, and outcomes were similar in the two groups of patients. Moderate ANH, combined with tranexamic acid administration and on-demand shed blood reinfusion, may reduce allogeneic transfusion requirements in OPCAB patients.

IMPLICATIONS

We studied the blood-sparing effects of moderate acute normovolemic hemodilution (ANH) in 100 patients undergoing off-pump coronary surgery (OPCAB). Combined with tranexamic acid administration and shed blood reinfusion when the intraoperative bleeding exceeded 250 mL, ANH was effective in reducing the number of OPCAB patients who required allogeneic transfusions and the number of packed red blood cell units transfused.

Prophylactic Treatment with Desmopressin Does Not Reduce Postoperative Bleeding After Coronary Surgery in Patients Treated with Aspirin Before Surgery

The synthetic vasopressin analog desmopressin has hemostatic properties and may reduce postoperative bleeding after coronary artery bypass grafting (CABG). A study on the effects of recent aspirin ingestion on platelet function in cardiac surgery showed a greater impairment of platelet function in patients treated with aspirin <2 days before the operation. We evaluated the effects of desmopressin on postoperative bleeding in CABG patients who were treated with aspirin 75 or 160 mg until the day before surgery. The study was a prospective, randomized, double-blinded, placebo-controlled, parallel group trial. One-hundred patients were included and divided into two groups. One group received desmopressin 0.3 micro g/kg and the other received placebo (0.9% NaCl) after the neutralization of heparin with protamine sulfate. Postoperative blood loss was recorded for 16 h. The mean (SD) bleeding was 606 (237) mL in the desmopressin group and 601 (301) mL in the placebo group (P = 0.93), representing no significant difference (95% confidence interval, -107 to 117 mL). We conclude that desmopressin does not reduce postoperative bleeding in CABG patients treated with aspirin until the day before surgery.

IMPLICATIONS

Continuation of aspirin until the day before coronary artery bypass grafting may increase postoperative bleeding. The administration of desmopressin to these patients after the neutralization of heparin with protamine sulfate does not reduce postoperative bleeding.

Evaluation of a novel kallikrein inhibitor on hemostatic activation in vitro

BACKGROUND

DX-88 is a potent kallikrein inhibitor that is being studied for the treatment of hereditary angioedema (HAE) and represents a potential alternative to aprotinin in cardiac surgical patients. The current study was designed to evaluate in vitro effects of DX-88 on coagulation in comparison with aprotinin.

METHODS

Blood samples were obtained from consented 12 healthy volunteers. DX-88 or aprotinin was added to blood at 200 and 800 kallikrein inhibitory units (KIU) per milliliter for aprotinin, and at 1.1, 2.2, or 8.8 microg/ml for DX-88. Thromboelastography (TEG) was performed using celite, kaolin, or tissue factor (TF) activation. Kaolin-based activated clotting times (ACTs) were measured at different heparin levels. The whole blood prothrombin time (PT)/PTT values were also measured. The endogenous thrombin generation was assessed with a fluorogenic assay using platelet-poor plasma (PPP).

RESULTS

With celite and kaolin activation of TEG, the reaction time was prolonged with DX-88 and aprotinin. With tissue factor activation, TEG parameters were not affected. DX-88 caused dose-dependent kaolin-ACT prolongation that was augmented by increasing doses of heparin. DX-88 or aprotinin had no significant effects on the PT values, but PTT values were dose-dependently prolonged. Both agents delayed the onset of thrombin generation when PTT reagent was used as a trigger, whereas no change was observed when tissue factor was used.

CONCLUSION

We found that DX-88 delayed contact activator induced coagulation without affecting tissue factor mediated coagulation. For evaluation of coagulation during DX-88 therapy, the use of PT or tissue factor-activated TEG may be preferable.

Current status of antifibrinolytics in cardiopulmonary bypass and elective deep hypothermic circulatory arrest

Cardiopulmonary bypass (CPB) results in many physiologic derangements, including activation of the hemostatic and fibrinolytic pathways. Deep hypothermic circulatory arrest (DHCA) adds a further insult to the coagulation systems because it involves more extreme hypothermia and organ ischemia related to blood stasis. The abnormalities induced by CPB disrupt the checks and balances in the hemostatic and fibrinolytic systems, resulting in a pathologic state that leads to excessive bleeding and other perioperative complications. Prophylactic antifibrinolytic therapy can attenuate the response to this insult by restoring the delicate balance within these systems, potentially reducing the complication rate and improving patient outcomes.

Single-dose tranexamic acid reduces postoperative bleeding after coronary surgery in patients treated with aspirin until surgery

Tranexamic acid reduces postoperative bleeding after coronary artery bypass grafting. We evaluated the effects of a single dose of tranexamic acid given immediately before cardiopulmonary bypass (CPB) in patients treated with aspirin until the day before surgery. The study was a prospective, randomized, double-blinded, placebo-controlled, parallel-group trial. Eighty patients were included and divided into two groups: one group received tranexamic acid 30 mg/kg, and one group received placebo (0.9% NaCl) as a bolus injection before CPB. Postoperative blood loss was recorded for 16 h. Transfusions of blood products were recorded for the whole hospital stay. Transfusions of packed red cells were given when the hematocrit value was less than 20% during CPB and less than 25% after surgery. The patients in the tranexamic acid group had significantly less postoperative bleeding compared with the patients in the placebo group (mean [SD]) (475 [274] mL versus 713 [243] mL; P < 0.001). An effective inhibition of fibrinolysis was found in patients receiving tranexamic acid. Tranexamic acid reduces postoperative bleeding in coronary artery bypass grafting patients treated with aspirin until the day before surgery.

IMPLICATIONS

Continuation of aspirin medication until the day before coronary artery bypass grafting may increase postoperative bleeding. The administration of a single dose of tranexamic acid (30 mg/kg) immediately before cardiopulmonary bypass significantly reduced postoperative bleeding and inhibited fibrinolysis in these patients.

Safety and efficacy of methods for reducing perioperative allogeneic transfusion: a critical review of the literature

A number of pharmacologic and nonpharmacologic technologies are in current use to minimize perioperative homologous blood use. Clinical trials, many of them randomized controlled trials, have been done evaluating these approaches and have demonstrated their efficacy. However, data on safety has relied mostly on case reports, uncontrolled studies, and, for the pharmacologic agents, extrapolation from the nonsurgical setting. In this review I analyze the data from the randomized trials and the lower-level evidence studies to provide the best estimates in safety with these alternatives. In general, these alternatives are safe with proper dosing and monitoring of effects. With aprotinin, the primary concern is anaphylaxis, and this predominantly with re-exposure. With aprotinin and with the anti-fibrinolytics, increased venous thromboembolic risk has not been a consistent finding. Tranexamic acid use intraoperatively is advantageous, but postoperative use appears to have no advantage and may be associated with renal dysfunction. DDAVP is low-risk, provided it is not overused, which can induce hyponatremia. Autologous predonation probably has similar risks as homologous blood with respect to transfusion errors and bacterial infection. As with most medical interventions, we must be vigilant to prevent human error.

Mechanisms and attenuation of hemostatic activation during extracorporeal circulation

Patients undergoing cardiac surgery with cardiopulmonary bypass are at risk for excessive microvascular bleeding, which often leads to transfusion of allogeneic blood and blood components as well as reexploration in a smaller subset of patients. Excessive bleeding after cardiac surgery is generally related to a combination of several alterations in the hemostatic system pertaining to hemodilution, excessive activation of the hemostatic system, and potentially the use of newer, longer-acting antiplatelet or antithrombotic agents. Although several nonpharmacologic strategies have been proposed, this review summarizes the role of pharmacologic interventions as means to attenuate the alterations in the hemostatic system during CPB in an attempt to reduce excessive bleeding, transfusion, and reexploration. Specifically, agents that inhibit platelets, fibrinolysis, factor Xa and thrombin, as well as broad-spectrum agents, have been investigated with respect to their role in reducing consumption of clotting factors and better preservation of platelet function. Prophylactic administration of agents with antifibrinolytic, anticoagulant, and possibly antiinflammatory properties can decrease blood loss and transfusion. Although aprotinin seems to be the most effective blood conservation agent (which is most likely related to its broad-spectrum nature), agents with isolated antifibrinolytic properties may be as effective in low-risk patients. The ability to reduce blood product transfusions and to decrease operative times and reexploration rates favorably affects patient outcomes, availability of blood products, and overall health care costs.

Antifibrinolytic agents and desmopressin as hemostatic agents in cardiac surgery

OBJECTIVE

To review the use of systemic hemostatic medications for reducing bleeding and transfusion requirements with cardiac surgery.

DATA SOURCES

Articles were obtained through computerized searches involving MEDLINE (from 1966 to September 2000). Additionally, several textbooks containing information on the diagnosis and management of bleeding associated with cardiac surgery were reviewed. The bibliographies of retrieved publications and textbooks were reviewed for additional references.

STUDY SELECTION

Due to the large number of randomized investigations involving systemic hemostatic medications for reducing bleeding associated with cardiac surgery, the article selection process focused on recent randomized controlled trials, metaanalyses and pharmacoeconomic evaluations.

DATA EXTRACTION

The primary outcomes extracted from the literature were blood loss and associated transfusion requirements, although other outcome measures such as mortality were extracted when available.

DATA SYNTHESIS

Although the majority of investigations for reducing cardiac bleeding and transfusion requirements have involved aprotinin, evidence from recent meta-analyses and randomized trials indicates that the synthetic antifibrinolytic agents, aminocaproic acid and tranexamic acid, have similar clinical efficacy. Additionally, aminocaproic acid (and to a lesser extent tranexamic acid) is much less costly. More comparative information of hemostatic agents is needed retative to other outcomes (eg., reoperation rates, myocardial infarction, stroke). There is insufficient evidence to recommend the use of desmopressin for reducing bleeding and transfusion requirements in cardiac surgery, although certain subsets of patients may benefit from its use.

CONCLUSIONS

Of the medications that have been used to reduce bleeding and transfusion requirements with cardiac surgery, the antifibrinolytic agents have the best evidence supporting their use. Aminocaproic acid is the least costly therapy based on medication costs and transfusion requirements.