Clinical value of early assessment of hyperfibrinolysis by rotational thromboelastometry during postpartum hemorrhage for the prediction of severity of bleeding: A multicenter prospective cohort study in the Netherlands

When to use tranexamic acid for the treatment of major bleeding?

Tranexamic acid (TXA) is an antifibrinolytic agent originally developed for the management of bleeding in the setting of postpartum hemorrhage (PPH). Over the last 15 years, there has been accumulating evidence on the use of TXA for the treatment of active bleeding in a variety of clinical contexts. Clinical trials have shown that the efficacy and safety of TXA for the treatment of bleeding differ according to the clinical context in which it is being administered, timing of administration, and dose. Early administration is important for efficacy, particularly in trauma and PPH. Further studies are needed to understand the mechanisms by which TXA provides benefit, optimal modes of administration and dosing, and its effect in some clinical settings, such as spontaneous intracerebral hemorrhage. There is no evidence that TXA increases the risk of thrombotic events in patients with major bleeding overall. However, there is evidence of increased risk of venous thrombosis in patients with gastrointestinal bleeding. There is also evidence of increased risk of seizures with the use of higher doses. This review summarizes the current evidence for the use of TXA for patients with active bleeding and highlights the importance of generating evidence of efficacy and safety of hemostatic interventions specific to the bleeding contexts-as findings from 1 clinical setting may not be generalizable to other contexts-and that of individual patient assessment for bleeding, thrombotic, and other risks, as well as important logistical and other practical considerations, to optimize care and outcomes in these settings.

Concentration-effect relationship for tranexamic acid inhibition of tissue plasminogen activator-induced fibrinolysis in vitro using the viscoelastic ClotPro® TPA-test

BACKGROUND

Tranexamic acid is an antifibrinolytic drug that is commonly administered for obstetric haemorrhage. Conventional viscoelastic tests are not sensitive to tranexamic acid, but the novel ClotPro® TPA-test can measure tranexamic acid-induced inhibition of fibrinolysis. We aimed to evaluate the TPA-test in pregnant and non-pregnant women.

METHODS

We performed an in vitro study of whole blood samples spiked with tranexamic acid from pregnant women in the first, second, and third trimester (n=20 per group) and from non-pregnant women (n=20). We performed ClotPro TPA-tests of whole blood sample and ClotPro EX-tests, FIB-tests, and TPA-tests.

RESULTS

Clot lysis was inhibited in a concentration-dependent manner up to a tranexamic acid concentration of 6.25 mg L-1. At tranexamic acid concentrations of 12.5 mg L-1 and above, clot lysis was completely inhibited. The concentration-effect relationship of tranexamic acid did not differ in a clinically important manner in blood from pregnant women across all three trimesters or from non-pregnant controls. A median maximum lysis cut-off value of at9 least 16% (25-75th percentiles 15-18), a median clot lysis time of 3600 s (25-75th percentiles 3600-3600), or both was associated with a tranexamic acid concentration of least 12.5 mg L-1.

CONCLUSIONS

The ClotPro® TPA-test is sensitive in detecting inhibition of fibrinolysis by tranexamic acid in whole blood samples of pregnant and non-pregnant women. The concentration-effect relationship of tranexamic acid to inhibit fibrinolysis in whole blood did not differ for women in the first, second, and third trimester or for non-pregnant women.

Fibrinolytic potential as a risk factor for postpartum hemorrhage

Background

Postpartum hemorrhage (PPH) is still the leading cause of maternal morbidity and mortality worldwide. While impaired fibrin polymerization plays a crucial role in the development and progress of PPH, recent approaches using viscoelastic measurements have failed to sensitively detect early changes in fibrinolysis in PPH. This study aimed to evaluate whether women experiencing PPH show alterations in POC-VET fibrinolytic potential during childbirth and whether fibrinolytic potential offers benefits in the prediction and treatment of PPH.

Methods

Blood samples were collected at three different timepoints: T0 = hospital admission (19 h ± 18 h prepartum), T1 = 30-60 min after placental separation, and T2 = first day postpartum (19 h ± 6 h postpartum). In addition to standard laboratory tests, whole-blood impedance aggregometry (Multiplate) and viscoelastic testing (VET) were performed using the ClotPro system, which included the TPA-test lysis time, to assess the POC-VET fibrinolytic potential, and selected coagulation factors were measured. The results were correlated with blood loss and clinical outcome markers. Severe PPH was defined as a hemoglobin drop > 4g/dl and/or the occurrence of shock or the need for red blood cell transfusion.

Results

Blood samples of 217 parturient women were analyzed between June 2020 and December 2020 at Heidelberg University Women's Hospital, and 206 measurements were eligible for the final analysis. Women experiencing severe PPH showed increased fibrinolytic potential already at the time of hospital admission. When compared to non-PPH, the difference persisted 30-60 min after placental separation. A higher fibrinolytic potential was accompanied by a greater drop in fibrinogen and higher d-dimer values after placental separation. While 70% of women experiencing severe PPH showed fibrinolytic potential, 54% of those without PPH showed increased fibrinolytic potential as well.

Conclusion

We were able to show that antepartal and peripartal fibrinolytic potential was elevated in women experiencing severe PPH. However, several women showed high fibrinolytic potential but lacked clinical signs of PPH. The findings indicate that high fibrinolytic potential is a risk factor for the development of coagulopathy, but further conditions are required to cause PPH.

Novel concepts and improvisation for treating postpartum haemorrhage: a narrative review of emerging techniques

BACKGROUND

Most treatments for postpartum haemorrhage (PPH) lack evidence of effectiveness. New innovations are ubiquitous but have not been synthesized for ready access.

NARRATIVE REVIEW

Pubmed 2020 to 2021 was searched on 'postpartum haemorrhage treatment', and novel reports among 755 citations were catalogued. New health care strategies included early diagnosis with a bundled first response and home-based treatment of PPH. A calibrated postpartum blood monitoring tray has been described. Oxytocin is more effective than misoprostol; addition of misoprostol to oxytocin does not improve treatment. Heat stable carbetocin has not been assessed for treatment. A thermostable microneedle oxytocin patch has been developed. Intravenous tranexamic acid reduces mortality but deaths have been reported from inadvertent intrathecal injection. New transvaginal uterine artery clamps have been described. Novel approaches to uterine balloon tamponade include improvised and purpose-designed free-flow (as opposed to fixed volume) devices and vaginal balloon tamponade. Uterine suction tamponade methods include purpose-designed and improvised devices. Restrictive fluid resuscitation, massive transfusion protocols, fibrinogen use, early cryopreciptate transfusion and point-of-care viscoelastic haemostatic assay-guided blood product transfusion have been reported. Pelvic artery embolization and endovascular balloon occlusion of the aorta and pelvic arteries are used where available. External aortic compression and direct compression of the aorta during laparotomy or aortic clamping (such as with the Paily clamp) are alternatives. Transvaginal haemostatic ligation and compression sutures, placental site sutures and a variety of novel compression sutures have been reported. These include Esike's technique, three vertical compression sutures, vertical plus horizontal compression sutures, parallel loop binding compression sutures, uterine isthmus vertical compression sutures, isthmic circumferential suture, circumferential compression sutures with intrauterine balloon, King's combined uterine suture and removable retropubic uterine compression suture. Innovative measures for placenta accreta spectrum include a lower uterine folding suture, a modified cervical inversion technique, bilateral uterine artery ligation with myometrial excision of the adherent placenta and cervico-isthmic sutures or a T-shaped lower segment repair. Technological advances include cell salvage, high frequency focussed ultrasound for placenta increta and extra-corporeal membrane oxygenation.

CONCLUSIONS

Knowledge of innovative methods can equip clinicians with last-resort options when faced with haemorrhage unresponsive to conventional methods.

Comparison of European recommendations about patient blood management in postpartum haemorrhage

Postpartum haemorrhage (PPH) is the leading cause of maternal mortality and morbidity worldwide. Some documents with practical recommendations for the management of PPH do not include the most updated directives. This review offers a quality comparison of the recommendations stated in Europe since 2015. A literature search was conducted to identify the documents published in Europe from 2015 to 2020 containing recommendations about management of PPH. The search returned 10 publications. A narrative synthesis and a summary of the information about PPH definition and its management were performed. Differences in the definition of PPH were identified: some documents considered the delivery procedure, and many publications included severity criteria. The therapeutic goal for red blood cells transfusion ranged from 6 to 9 g/dl. There were divergences in the need for considering haemostatic results before fresh frozen plasma transfusion. The therapeutic goal of platelet transfusion ranged from 50 x 10⁹ to 100 x 10⁹  μ/L. There was a wide consensus about the therapeutic goal of fibrinogen replacement (>2 g/L), but not about its use in an unmonitored or pre-emptive manner. Most publications included therapeutic approaches such as tranexamic acid and recombinant factor VII activated, but not prothrombin complex concentrate or coagulation factor XIII. The recommendations about PPH management offered in European documents are heterogeneous and have changed over time. The standardisation of all them could be useful to make progress in PPH clinical management and research which, in turn, could strongly impact in patient outcomes.