Tranexamic acid – A narrative review for the emergency medicine clinician

A mechanism for hereditary angioedema caused by a methionine-379-to-lysine substitution in kininogens

ABSTRACT

Hereditary angioedema (HAE) is associated with episodic kinin-induced swelling of the skin and mucosal membranes. Most patients with HAE have low plasma C1-inhibitor activity, leading to increased generation of the protease plasma kallikrein (PKa) and excessive release of the nanopeptide bradykinin from high-molecular-weight kininogen (HK). However, disease-causing mutations in at least 10% of patients with HAE appear to involve genes for proteins other than C1-inhibitor. A point mutation in the Kng1 gene encoding HK and low-molecular weight kininogen (LK) was identified recently in a family with HAE. The mutation changes a methionine (Met379) to lysine (Lys379) in both proteins. Met379 is adjacent to the Lys380-Arg381 cleavage site at the N-terminus of the bradykinin peptide. Recombinant wild-type (Met379) and variant (Lys379) versions of HK and LK were expressed in HEK293 cells. PKa-catalyzed kinin release from HK and LK was not affected by the Lys379 substitutions. However, kinin release from HK-Lys379 and LK-Lys379 catalyzed by the fibrinolytic protease plasmin was substantially greater than from wild-type HK-Met379 and LK-Met379. Increased kinin release was evident when fibrinolysis was induced in plasma containing HK-Lys379 or LK-Lys379 compared with plasma containing wild-type HK or LK. Mass spectrometry revealed that the kinin released from wild-type and variant kininogens by PKa is bradykinin. Plasmin also released bradykinin from wild-type kininogens but cleaved HK-Lys379 and LK-Lys379 after Lys379 rather than Lys380, releasing the decapeptide Lys-bradykinin (kallidin). The Met379Lys substitutions make HK and LK better plasmin substrates, reinforcing the relationship between fibrinolysis and kinin generation.

Awareness and use of tranexamic acid in the management of postpartum hemorrhage among health care professionals in Enugu, Nigeria

OBJECTIVES

This study was conducted to determine the knowledge, practice, and barriers regarding the use of tranexamic acid (TXA) for the prevention and treatment of postpartum hemorrhage (PPH) among health care providers in Enugu, Nigeria.

METHODS

A cross-sectional study was conducted among health professionals (doctors, pharmacists, and nurses) in two Nigerian tertiary teaching hospitals (one federal and one state). A total of 220 questionnaires were distributed and 207 were returned (response rate: 94%) and analyzed using SPSS for inferential statistics with a level of significance of P < 0.05.

RESULTS

Only 23.7% of the respondents had good knowledge of TXA use in PPH (P < 0.001), and awareness of the recent World Health Organization (WHO) recommendation on the use of TXA for PPH was low (19.8%, P < 0.001). The majority of the respondents had neither prescribed nor dispensed TXA (30%, P < 0.001). Very few respondents used TXA for all cases of PPH (16.4%, P < 0.001). Barriers against its use include nonawareness of the latest WHO recommendation, preference for other uterotonics, and cost of the drug.

CONCLUSIONS

There was poor knowledge of TXA, poor awareness of its recommendation, and low use for PPH among different cadres of health care providers.

The Role of Tranexamic Acid in Sleeve Gastrectomy: A Systematic Review and Meta-Analysis

Tranexamic acid (TXA) is an essential procoagulant drug used in various intra- and postoperative situations. Its efficacy and safety profile in obese cases undergoing laparoscopic sleeve gastrectomy (LSG) is still unresolved. Therefore, this meta-analysis evaluated and investigated the current intra- and postoperative effects and hazards of TXA on patients undergoing LSG. As for methodology, Web of Science, Cochrane Library, Scopus, and PubMed were thoroughly searched for relevant studies. Retrieved results were prepared for screening through Endnote, helping to identify eligible studies. Relevant patient characteristics and outcomes were extracted. The methodological quality of the relevant studies was appraised using the respected appraisal tool. Six studies of different designs were enrolled, comprising 753 cases that underwent LSG and administered TXA. Their mean BMI and age went from 37.3 to 56.25 kg/m2 and 33.5 to 43.25 years, respectively. Tranexamic acid significantly linked to reduction in intraoperative bleeding instances, operative blood loss, and operative duration, compared to placebo ((RR = 0.66, 95% CI [0.44, 0.98], P=0.04, I2 = 81%); (MD = -39.64, 95%CI [-75.49, -3.78], P=0.03, I2=94%); (MD=-5.84, 95%CI [-9.62, -2.05], P=0.003, I2=73%)). Tranexamic acid also significantly showed superiority regarding postoperative bleeding events and duration of hospitalization compared to the control group ((RR= 0.45, 95%CI [0.29, 0.69], P=0.0002, I2 =0%); (MD=-0.24, 95%CI [-0.32, -0.17], P< 0.0000, I2 =0%)). Moreover, follow-up of the enrolled patients for a minimum of three to six months resulted in no reported thromboembolic instances, suggesting a negligible risk for thromboembolism among patients undergoing LSG and receiving TXA. In conclusion, tranexamic acid demonstrates a robust safety and efficacy profile for its use in patients undergoing LSG, with no reported instances of thromboembolism. Variations in TXA administration regimens, bleeding definitions, procedural techniques, and potential confounding medications could not be accounted for, necessitating additional large-scale RCTs to address and bridge knowledge gaps.

Comparative study between oxytocin and combination of tranexamic acid and ethamsylate in reducing intra-operative bleeding during emergency and elective cesarean section after 38 weeks of normal pregnancy

OBJECTIVE

Cesarean Section (CS) is associated with an increased risk of hemorrhage. Many drugs are used to decrease this risk. We aim to compare the combination of ethamsylate and tranexamic acid, oxytocin, and placebo in women undergoing CS.

METHODS

We conducted a double-blinded, randomized, placebo-controlled trial between October and December 2020 in four university hospitals in Egypt. The study included all pregnant women in labor without any complications who accepted to participate in the study between October and December 2020. The participants were divided into three groups. The subjects were randomly allocated to receive either oxytocin (30 IU in 500 ml normal saline during cesarean section), combined one gram of tranexamic acid with 250 mg of ethamsylate once before skin incision, or distilled water. Our main outcome was the amount of blood loss during the operation. The secondary outcomes were the need for blood transfusion, hemoglobin and hematocrit changes, hospital stay, operative complications, and the need for a hysterectomy. The one-way ANCOVA test was used to compare the quantitative variables between the three groups while the Chi-square test was used to compare the qualitative variables. Post hoc analysis then was performed to compare the difference between every two groups regarding the quantitative variables.

RESULTS

Our study included 300 patients who were divided equally into three groups. Tranexamic acid with ethamsylate showed the least intra-operative blood loss (605.34 ± 158.8 ml) compared to oxytocin (625.26 ± 144.06) and placebo (669.73 ± 170.69), P = 0.015. In post hoc analysis, only tranexamic acid with ethamsylate was effective in decreasing the blood loss compared to placebo (P = 0.013); however, oxytocin did not reduce blood loss compared to saline (P = 0.211) nor to tranexamic acid with ethamsylate (P = 1). Other outcomes and CS complications showed no significant difference between the three groups except for post-operative thrombosis which was significantly higher in the tranexamic and ethamsylate group, P < 0.00001 and the need for a hysterectomy which was significantly increased in the placebo group, P = 0.017.

CONCLUSION

The combination of tranexamic acid and ethamsylate was significantly associated with the least amount of blood loss. However, in pairwise comparisons, only tranexamic acid with ethamsylate was significantly better than saline but not with oxytocin. Both oxytocin and tranexamic acid with ethamsylate were equally effective in reducing intra-operative blood loss and the risk of hysterectomy; however, tranexamic acid with ethamsylate increased the risk of thrombotic events. Further research with a larger number of participants is needed.

TRIAL REGISTRATION

The study was registered on Pan African Clinical Trials Registry with the following number: PACTR202009736186159 and was approved on 04/09/2020.

Severe Trauma-Induced Coagulopathy: Molecular Mechanisms Underlying Critical Illness

Trauma remains one of the leading causes of death in adults despite the implementation of preventive measures and innovations in trauma systems. The etiology of coagulopathy in trauma patients is multifactorial and related to the kind of injury and nature of resuscitation. Trauma-induced coagulopathy (TIC) is a biochemical response involving dysregulated coagulation, altered fibrinolysis, systemic endothelial dysfunction, platelet dysfunction, and inflammatory responses due to trauma. The aim of this review is to report the pathophysiology, early diagnosis and treatment of TIC. A literature search was performed using different databases to identify relevant studies in indexed scientific journals. We reviewed the main pathophysiological mechanisms involved in the early development of TIC. Diagnostic methods have also been reported which allow early targeted therapy with pharmaceutical hemostatic agents such as TEG-based goal-directed resuscitation and fibrinolysis management. TIC is a result of a complex interaction between different pathophysiological processes. New evidence in the field of trauma immunology can, in part, help explain the intricacy of the processes that occur after trauma. However, although our knowledge of TIC has grown, improving outcomes for trauma patients, many questions still need to be answered by ongoing studies.

Role of Tranexamic Acid (TXA) in Preventing Bleeding Following Sleeve Gastrectomy: a Systematic Review and Meta-analysis

BACKGROUND

Tranexamic acid (TXA) has drawn growing interest over the last decade for its benefit in optimizing post-operative bleeding, yet its role in bariatric surgery is poorly understood.

METHODS

The medical librarian developed and executed comprehensive searches on September 28, 2022. The population of interest included adults who underwent elective bariatric surgery. The intervention was tranexamic acid administration while the comparison was placebo or standard peri-operative therapy. The primary outcome of interest was post-operative bleeding which was defined a priori.

RESULTS

A total of four studies were identified comprising of 475 patients. Of those, 207 (50%) received TXA at induction and all underwent laparoscopic sleeve gastrectomy (LSG). The majority of patients were female (n = 343, 80.7%) with ages ranging from 17 to 70 years of age and mean BMIs ranging from 37 to 56 kg/m². Post-operative bleeding after LSG ranged from 0 to 28% depending on bleed definition and TXA administration with no differences in venous thromboembolic events or mortality between groups. Meta-analysis of post-operative bleeding demonstrated a statistically significant benefit with TXA administration (OR 0.40; 95% CI 0.23-0.70; p = 0.001) for patients undergoing elective LSG.

CONCLUSIONS

Intravenous tranexamic acid at the time of laparoscopic sleeve gastrectomy is associated with a significant reduction of post-operative bleeding with no observed differences in thromboembolic events or mortality. Further high-quality studies are needed to better delineate the ideal bariatric population to receives TXA in addition to the optimal timing, dose, and duration of TXA therapy.

Impact of intravesical administration of tranexamic acid on gross hematuria in the emergency department: A before-and-after study

INTRODUCTION

Local applications of tranexamic acid (TXA) have been effective in treating various hemorrhagic conditions. In patients with gross hematuria, the main treatment in the emergency department (ED) is continuous bladder irrigation (CBI). However, CBI has no pharmacological effects except blood clot removal from dilution. The aim of this study was to evaluate the impact of the intravesical TXA injection before CBI.

METHODS

This study was a before-and-after, retrospective, and single-center study. The target population was hematuria patients who received CBI via a 3-way Foley catheter. As the intervention procedure, 1000 mg of TXA was injected through the Foley catheter and after 15 min, the Foley catheter was declamped and CBI started. Since the intervention started in March 2022, the patients from March 2022 to August 2022 were assigned to the after group and the patients from March 2021 to August 2021 were assigned to the before group. The primary outcomes were the length of stay in the ED and duration of Foley catheter placement. The secondary outcomes were the admissions and the revisits for CBI within 48 h after discharge.

RESULTS

The numbers of patients in the before group and after group were 73 and 86, respectively. The median length of stay in the ED was shorter in the intervention group than in the group not treated with TXA (274 min vs. 411 mins, P < 0.001). The median duration of Foley catheter placement was also shorter in the intervention group than not treated with TXA (145 min vs. 308 mins, P < 0.001). The revisits after ED discharge were lower in the after group than in the before group (2.3% vs. 12.3%, P = 0.031). There was a trend for lower admissions in the TXA treatment group than before group (29.1% vs. 45.2%, P = 0.052).

CONCLUSION

After the TXA intervention, reduction in the length of stay in the ED, the duration of Foley catheter placement, and the revisits after ED discharge was observed.