Thromboelastography versus Standard Coagulation Assays in Patients with Postpartum Hemorrhage

OBJECTIVE

Thromboelastography (TEG), a point-of-care test that measures blood's dynamic viscoelastic properties, is routinely used to guide resuscitation in surgical specialties with high hemorrhage risk. Patients with ongoing postpartum hemorrhage (PPH) often develop coagulopathy and hypofibrinogenemia. Timely assessment of fibrinogen is crucial because cryoprecipitate for repletion requires thawing time prior to administration. TEG may provide rapid assessment of coagulopathy in ongoing hemorrhage but this has not been thoroughly studied. Our objective was to determine if TEG accurately reflects coagulopathy in ongoing PPH when compared with standard assays.

STUDY DESIGN

This was a retrospective cohort study of people with ongoing PPH (quantified blood loss >1,000 mL), from January 1, 2016, to December 31, 2019. TEG variables and standard coagulation parameters were compared in patients who had both assays drawn simultaneously. As a secondary analysis, patients who had TEG were compared with those who did not. The Mann-Whitney, Fisher's exact, Kruskal-Wallis, Spearman's rho, and logistic regression tests were used for analysis. Significance was set at p < 0.05.

RESULTS

A total of 680 patients were included, 69 of whom had TEG and coagulation parameters drawn simultaneously and were included in the primary analysis. The remainder were included in the secondary analysis. TEG variables and coagulation assays correlated significantly-prolonged R with increased PTT (rho 0.25, p = 0.04), prolonged K and decreased α angle with decreased fibrinogen (rho -0.61, p < 0.001; rho 0.24, p < 0.001), and decreased maximum amplitude with decreased platelets (rho 0.62, p < 0.001). Those who had thromboelastographic assays had higher blood loss and need for interventions to manage hemorrhage than those who did not.

CONCLUSION

TEG correlated significantly with standard laboratory assays in ongoing PPH, including for patients with hypofibrinogenemia. Given the point-of-care nature and rapid turnaround time, TEG should be considered for timely hemorrhage evaluation and directed resuscitation of coagulopathy.

KEY POINTS

· TEG significantly correlates with standard laboratory measures of coagulopathy in postpartum hemorrhage, including in patients with hybofibrinogemia (fibrinogen <200).. · TEG is routinely used in nonobstetric hemorrhage, and should be considered in PPH.. · Due to the point-of-care nature, TEG may allow for rapid guided resuscitation, including fibrinogen..

Placental abruption at near-term and term gestations: pathophysiology, epidemiology, diagnosis, and management

Placental abruption is the premature separation of the placenta from its uterine attachment before the delivery of a fetus. The clinical manifestations of abruption typically include vaginal bleeding and abdominal pain with a wide variety of abnormal fetal heart rate patterns. Clinical challenges arise when pregnant people with this condition present with profound vaginal bleeding, necessitating urgent delivery, especially when there is a concern for maternal and fetal compromise and coagulopathy. Abruption occurs in 0.6% to 1.2% of all pregnancies, with nearly half of abruption occurring at term gestations. An exposition of abruption at near-term (defined as the late preterm period from 34 0/7 to 36 6/7 weeks of gestation) and term (defined as ≥37 weeks of gestation) provides unique insights into its direct effects, as risks associated with preterm birth do not impact outcomes. Here, we explore the pathophysiology, epidemiology, and diagnosis of abruption. We discuss the interaction of chronic processes (decidual and uteroplacental vasculopathy) and acute processes (shearing forces applied to the abdomen) that underlie the pathophysiology. Risk factors for abruption and strengths of association are summarized. Sonographic findings of abruption and fetal heart rate tracings are presented. In addition, we propose a management algorithm for acute abruption that incorporates blood loss, vital signs, and urine output, among other factors. Lastly, we discuss blood component therapy, viscoelastic point-of-care testing, disseminated intravascular coagulopathy, and management of abruption complicated by fetal death. The review seeks to provide comprehensive, clinically focused guidance during a gestational age range when neonatal outcomes can often be favorable if rapid and evidence-based care is optimized.

Management of severe peri-operative bleeding: Guidelines from the European Society of Anaesthesiology and Intensive Care: Second update 2022

BACKGROUND

Management of peri-operative bleeding is complex and involves multiple assessment tools and strategies to ensure optimal patient care with the goal of reducing morbidity and mortality. These updated guidelines from the European Society of Anaesthesiology and Intensive Care (ESAIC) aim to provide an evidence-based set of recommendations for healthcare professionals to help ensure improved clinical management.

DESIGN

A systematic literature search from 2015 to 2021 of several electronic databases was performed without language restrictions. Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used to assess the methodological quality of the included studies and to formulate recommendations. A Delphi methodology was used to prepare a clinical practice guideline.

RESULTS

These searches identified 137 999 articles. All articles were assessed, and the existing 2017 guidelines were revised to incorporate new evidence. Sixteen recommendations derived from the systematic literature search, and four clinical guidances retained from previous ESAIC guidelines were formulated. Using the Delphi process on 253 sentences of guidance, strong consensus (>90% agreement) was achieved in 97% and consensus (75 to 90% agreement) in 3%.

DISCUSSION

Peri-operative bleeding management encompasses the patient's journey from the pre-operative state through the postoperative period. Along this journey, many features of the patient's pre-operative coagulation status, underlying comorbidities, general health and the procedures that they are undergoing need to be taken into account. Due to the many important aspects in peri-operative nontrauma bleeding management, guidance as to how best approach and treat each individual patient are key. Understanding which therapeutic approaches are most valuable at each timepoint can only enhance patient care, ensuring the best outcomes by reducing blood loss and, therefore, overall morbidity and mortality.

CONCLUSION

All healthcare professionals involved in the management of patients at risk for surgical bleeding should be aware of the current therapeutic options and approaches that are available to them. These guidelines aim to provide specific guidance for bleeding management in a variety of clinical situations.

Latest advances in postpartum hemorrhage management

Hemorrhage is the leading cause of maternal mortality worldwide. A maternal health priority is improving how healthcare providers prevent and manage postpartum hemorrhage (PPH). Because anesthesiologists can help facilitate how hospitals develop approaches for PPH prevention and anticipatory planning, we review the potential utility of PPH risk-assessment tools, bundles, and protocols. Anesthesiologists rely on clinical and diagnostic information for initiating and evaluating medical management. Therefore, we review modalities for measuring blood loss after delivery, which includes visual, volumetric, gravimetric, and colorimetric approaches. Point-of-care technologies for assessing changes in central hemodynamics (ultrasonography) and coagulation profiles (rotational thromboelastometry and thromboelastography) are also discussed. Anesthesiologists play a critical role in the medical and transfusion management of PPH. Therefore, we review blood ordering and massive transfusion protocols, fixed-ratio vs. goal-directed transfusion approaches, coagulation changes during PPH, and the potential clinical utility of the pharmacological adjuncts, tranexamic acid, and fibrinogen concentrate.

Point-of-Care Viscoelastic Tests in the Management of Obstetric Hemorrhage

Obstetric hemorrhage remains the leading cause of maternal morbidity and mortality worldwide. Thromboelastography and rotational thromboelastometry are laboratory methods of assessing the kinetics of blood clot formation through real-time measurement of viscoelastic clot strength and may aid in management of severe hemorrhage. Although first described more than 70 years ago, viscoelastic testing devices are now available that allow for rapid point-of-care use of this technology to aid in real-time management of blood product replacement in cases of severe hemorrhage. These devices can be used to visually estimate multiple facets of hemostasis-coagulation, platelet function, and fibrinolysis-within 10-20 minutes. They have been used successfully in cardiac surgery, trauma, and liver transplantation and have potential for use in management of obstetric hemorrhage. Goals with their use include targeted transfusion of blood and its components for specific coagulation deficiencies. To date, however, published experiences with the use of these viscoelastic tests for obstetric hemorrhage have been limited. Because of the increasing use of the point-of-care tests by anesthesiologists, surgeons, and intensivists, the purpose of this report is to familiarize obstetricians with the technology involved and its use in severe hemorrhage complicating pregnancy.

Viscoelastic haemostatic point-of-care assays in the management of postpartum haemorrhage: a narrative review

Viscoelastic haemostatic assays provide rapid testing at the bed-side that identify all phases of haemostasis, from initial fibrin formation to clot lysis. In obstetric patients, altered haemostasis is common as pregnancy is associated with coagulation changes that may contribute to bleeding events such as postpartum haemorrhage, as well as thrombosis events. In this narrative review, we examine the potential clinical utility of viscoelastic haemostatic assays in postpartum haemorrhage and consider the current recommendations for their use in obstetric patients. We discuss the clinical benefits associated with the use of viscoelastic haemostatic assays due to the provision of (near) real-time readouts with a short turnaround, coupled with the identification of coagulation defects such as hypofibrinogenaemia. The use of viscoelastic haemostatic assay-guided algorithms may be beneficial to diagnose coagulopathy, predict postpartum haemorrhage, reduce transfusion requirements and monitor fibrinolysis in women with obstetric haemorrhage. Further studies are required to assess whether viscoelastic haemostatic assay-guided treatment improves clinical outcomes, and to confirm the utility of prepartum viscoelastic haemostatic assay measurements for identifying patients at risk of postpartum haemorrhage.

DIC in Pregnancy - Pathophysiology, Clinical Characteristics, Diagnostic Scores, and Treatments

Obstetrical hemorrhage and especially DIC (disseminated intravascular coagulation) is a leading cause for maternal mortality across the globe, often secondary to underlying maternal and/or fetal complications including placental abruption, amniotic fluid embolism, HELLP syndrome (hemolysis, elevated liver enzymes and low platelets), retained stillbirth and acute fatty liver of pregnancy. Various obstetrical disorders can present with DIC as a complication; thus, increased awareness is key to diagnosing the condition. DIC patients can present to clinicians who may not be experienced in a variety of aspects of thrombosis and hemostasis. Hence, DIC diagnosis is often only entertained when the patient already developed uncontrollable bleeding or multi-organ failure, all of which represent unsalvageable scenarios. Beyond the clinical presentations, the main issue with DIC diagnosis is in relation to coagulation test abnormalities. It is widely believed that in DIC, patients will have prolonged prothrombin time (PT) and partial thromboplastin time (PTT), thrombocytopenia, low fibrinogen, and raised D-dimers. Diagnosis of DIC can be elusive during pregnancy and requires vigilance and knowledge of the physiologic changes during pregnancy. It can be facilitated by using a pregnancy specific DIC score including three components: 1) fibrinogen concentrations; 2) the PT difference - relating to the difference in PT result between the patient's plasma and the laboratory control; and 3) platelet count. At a cutoff of ≥26 points, the pregnancy specific DIC score has 88% sensitivity, 96% specificity, a positive likelihood ratio (LR) of 22, and a negative LR of 0.125. Management of DIC during pregnancy requires a prompt attention to the underlying condition leading to this complication, including the delivery of the patient, and correction of the hemostatic problem that can be guided by point of care testing adjusted for pregnancy.

Viscoelastic Hemostatic Assays for Postpartum Hemorrhage

This article discusses the importance and effectiveness of viscoelastic hemostatic assays (VHAs) in assessing hemostatic competence and guiding blood component therapy (BCT) in patients with postpartum hemorrhage (PPH). In recent years, VHAs such as thromboelastography and rotational thromboelastometry have increasingly been used to guide BCT, hemostatic adjunctive therapy and prohemostatic agents in PPH. The three pillars of identifying hemostatic competence include clinical observation, common coagulation tests, and VHAs. VHAs are advantageous because they assess the cumulative contribution of all components of the blood throughout the entire formation of a clot, have fast turnaround times, and are point-of-care tests that can be followed serially. Despite these advantages, VHAs are underused due to poor understanding of correct technique and result interpretation, a paucity of widespread standardization, and a lack of large clinical trials. These VHAs can also be used in cases of uterine atony, preeclampsia, acute fatty liver of pregnancy, amniotic fluid embolism, placental abruption, genital tract trauma, surgical trauma, and inherited and prepartum acquired coagulopathies. There exists an immediate need for a point-of-care test that can equip obstetricians with rapid results on developing coagulopathic states. The use of VHAs in predicting and treating PPH, although in an incipient state, can fulfill this need.

When and how should I transfuse during obstetric hemorrhage?

The incidence of maternal hemorrhage and blood transfusion has increased over time. Causes of massive hemorrhage, defined as a transfusion > 10 units of erythrocytes, include abnormal placental insertion, preeclampsia, and placental abruption. Although ratio-based transfusion has been described for managing massive hemorrhage, a goal-directed approach using laboratory or point-of-care data may lead to better outcomes. Autotransfusion, which involves the collection, washing, and filtration of maternal shed blood, avoids many of the complications associated with allogeneic blood transfusion. In this review, we provide an overview of transfusion practices related to the management of obstetric hemorrhage.

Viscoelastic Tests as Point-of-Care Tests in the Assessment and Management of Bleeding and Thrombosis in Liver Disease

Viscoelastic point-of-care (VET POC) tests provide a global assessment of hemostasis and have an increasing role in the management of bleeding and blood component delivery across several clinical settings. VET POC tests have a rapid turnaround time, provide a better overall picture of hemostasis, predict bleeding more accurately than conventional coagulation tests, and reduce blood component usage and health care costs. Despite commonly having abnormal conventional coagulation tests, most patients with chronic liver disease have a "rebalanced" hemostasis. However, this hemostatic balance is delicate and these patients are predisposed to both bleeding and thromboembolic events. Over recent years, VET POC tests have been increasingly studied for their potential as better functional tests of hemostasis in liver disease patients. This review provides a background on the most common VET POC tests (thromboelastography and rotational thromboelastometry) and discusses the current evidence for these tests in the prediction and management of bleeding and thrombosis in patients with chronic liver disease, and in liver resection and transplant. With the recent publication of several randomized controlled trials, there is growing evidence that VET POC tests may be used to improve bleeding risk assessment and reduce blood product use in liver disease patients outside of the transplant setting. However, consensus is still lacking regarding the VET POC tests' thresholds that should be used to trigger blood product transfusion. VET POC tests also show promise in predicting thrombosis in patients with liver disease, but further research is needed before they can be used to guide anticoagulant therapy.

Critical Care Society of Southern Africa adult patient blood management guidelines: 2019 Round-table meeting, CCSSA Congress, Durban, 2018

The CCSSA PBM Guidelines have been developed to improve patient blood management in critically ill patients in southern Africa. These consensus recommendations are based on a rigorous process by experts in the field of critical care who are also practicing in South Africa (SA). The process comprised a Delphi process, a round-table meeting (at the CCSSA National Congress, Durban, 2018), and a review of the best available evidence and international guidelines. The guidelines focus on the broader principles of patient blood management and incorporate transfusion medicine (transfusion guidelines), management of anaemia, optimisation of coagulopathy, and administrative and ethical considerations. There are a mix of low-middle and high-income healthcare structures within southern Africa. Blood products are, however, provided by the same not-for-profit non-governmental organisations to both private and public sectors. There are several challenges related to patient blood management in SA due most notably to a high incidence of anaemia, a frequent shortage of blood products, a small donor population, and a healthcare system under financial strain. The rational and equitable use of blood products is important to ensure best care for as many critically ill patients as possible. The summary of the recommendations provides key practice points for the day-to-day management of critically ill patients. A more detailed description of the evidence used to make these recommendations follows in the full clinical guidelines section.

Systematic review of viscoelastic testing (TEG/ROTEM) in obstetrics and recommendations from the women's SSC of the ISTH

Thromboelastography (TEG) and rotational thromboelastometry (ROTEM) are point-of-care viscoelastic devices that use whole blood samples to assess coagulation and fibrinolysis. These devices have been studied extensively in cardiac surgery, but there is limited robust evidence supporting its use in obstetrics. The hesitancy toward its routine use in obstetrics may be due to the current lack of randomized controlled trials and large observational studies. The study aims to systematically review studies that investigated TEG/ROTEM use in pregnancy or peripartum, and to provide recommendations for future studies to fill current research gaps. We performed a systematic review of studies on viscoelastic testing in obstetrics. Included studies were original research, used TEG or ROTEM during pregnancy or peripartum, and published in English. Ninety-three studies, spanning 31 years from 1989 to 2020 and with a total of 32,817 participants, were included. Sixty-two (66.7%) of the studies used TEG and 31 (33.3%) used ROTEM. To date, there are a total of two randomized controlled trials on TEG/ROTEM use in obstetrics. ROTEM may be used to guide transfusion therapy for postpartum hemorrhage. TEG and ROTEM can detect the hypercoagulable changes associated with pregnancy. Variability between study protocols and results suggests the need for future large prospective high-quality studies with standardized protocols to investigate the utility of TEG/ROTEM in assessing risk for thrombosis and hemorrhage as well as in guiding prophylaxis and treatment in obstetric patients. This review identifies the gaps and provides concrete recommendations for future studies to fill those gaps.

The role of viscoelastic testing in the management of the parturient

Viscoelastic testing is the measurement of how the viscoelastic properties of blood change as blood clots. In pregnancy, unique changes in clotting function occur overall to make the pregnant woman hypercoagulable. Viscoelastic testing may be able to play a role in guiding placement of epidural and spinal anesthetics by demonstrating enhanced coagulation function, even when there are individual parts of the coagulation system that are abnormal, for example, thrombocytopenia. These tools may also play a role in addressing the management of maternal hemorrhage, which in the United States is on the rise. This review discusses the opportunity to use viscoelastic testing in the parturient.

Treatment of Obstetric Hemorrhage with Fibrinogen Concentrate

Background

Postpartum hemorrhage (PPH) is related to several factors but is frequently associated with coagulopathy with maternal mortality. Fibrinogen is a very important agent for bleeding. When its concentration is decreased, severe surgical blood loss may occur. Here, we investigate the association of postpartum bleeding characteristics with evolution of PPH in patients who were taking fibrinogen concentrate (FC).

Material/Methods

PPH patients’ demographic parameters, outcome variables, and laboratory findings before and at ICU were recorded between January 2015 and July 2017. The duration of ICU stay and plasmapheresis, renal replacement therapy, maternal-fetal deaths, RBC, FFP, and PC replacement were calculated.

Results

Group I: Fibrinogen levels were ≤150 mg/dl (n: 31), Group II: Fibrinogen levels were >151 mg/dl (n: 18). In the peroperative period, there was no difference between the 2 groups in terms of RBC, FFP, or PC transfussion. In intraoperative and ICU admission period, patients in Group I had higher INR, APTT, and PT values than in the other group. FC replacement according to fibrinogen level was given, ranging from to 1 to 6 gr in Group I and 1–2 gr in Group II intraoperatively and at ICU 2–8 gr FC was given in both groups. In the intraoperative and ICU admission period, blood transfusion requirements of patients after fibrinogen replacement were evaluated and there was no statistically significant difference between groups. There were no differrences between groups in duration of intensive care unit stay, hospital stay, and mechanical ventilation.

Conclusions

Adequate FC therapy prevents unnecessary RBC, FFP, and PC replacement and prevents complications and volume overload.

Establishing a perinatal red blood cell transfusion risk evaluation model for obstetric patients: a retrospective cohort study

BACKGROUND

The ability to predict risk factors for blood transfusion after postpartum hemorrhage could enhance the performance of lifesaving procedures in patients who experience postpartum hemorrhage. Therefore, this study aimed to evaluate these risk factors and create a scoring system for blood transfusion evaluations and risk in obstetric patients.

STUDY DESIGN AND METHODS

Diagnosis and blood transfusion data of 14,112 women who delivered between January 1, 2015, and December 31, 2015, were analyzed. A binary logistic regression model was used. We conducted univariate analyses of each risk factor as well as multivariable logistic regression analysis. Data of obstetric patients in 2016 validated the receiver operating characteristic curve. A risk prediction score was generated from the transfusion risk factor β‐coefficients in the multivariable logistic regression model.

RESULTS

In total, 392 (2.94%) of 13,328 patients received transfusions. After multivariable adjustment, polyembryony, anemia, thrombocytopenia, preeclampsia, placenta previa, placental implantation, uterine scarring, uterine rupture, retained placenta, stillbirth, and HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets) were significantly associated with perinatal transfusion. Heart disease and hemophilia were not related to transfusion risk. The blood transfusion risk evaluation table was well calibrated.

CONCLUSIONS

Our retrospective analysis revealed that diagnoses including polyembryony, anemia, thrombocytopenia, preeclampsia, placenta previa, placenta implantation, uterine scarring, uterine rupture, retained placenta, stillbirth, and HELLP syndrome are significantly associated with perinatal transfusion and are risk factors for blood transfusion. The blood transfusion scoring system could be beneficial for evaluating blood transfusion risk.

New-Generation Thromboelastography: Comprehensive Evaluation of Citrated and Heparinized Blood Sample Storage Effect on Clot-Forming Variables

Context.—

Thromboelastography (TEG) is a whole blood, real-time analyzer measuring the viscoelastic properties of the hemostasis process and allowing for individualized goal-directed therapy. However, routine use of TEG requires validation of sample storage effect on clot parameters.

Objectives.—

To establish the minimum time required for equilibration time and the maximum time for sample storage for all commercially available TEG tests for the new-generation TEG 6s and to determine how those times compare with the older generation TEG 5000.

Design.—

Citrated and heparinized whole blood samples obtained from 20 healthy donors were analyzed for clot parameters at multiple time points for both the TEG 6s and the TEG 5000. Samples were activated with the citrated multichannel cartridge or the platelet-mapping cartridge in the TEG 6s or with recalcified kaolin in the TEG 5000.

Results.—

All blood samples yielded TEG parameter results within reference ranges and had a tendency toward hypercoagulable profiles with increased storage time. Sample storage resulted in increased platelet inhibition with significant differences at 4 hours in the platelet-mapping cartridge (arachidonic acid percentage of inhibition, P = .002; adenosine diphosphate percentage of inhibition, P = .02).

Conclusions.—

For nonemergent cases or in a central laboratory setting, all tests provided reliable results for up to 4 hours in the citrated multichannel cartridge and for 3 hours for platelet function information in the platelet-mapping cartridge. In emergent/urgent situations in which the sample needs to be run immediately, RapidTEG and functional fibrinogen tests may be preferred.

Thromboelastography (TEG) or thromboelastometry (ROTEM) to monitor haemostatic treatment versus usual care in adults or children with bleeding

BACKGROUND

Severe bleeding and coagulopathy are serious clinical conditions that are associated with high mortality. Thromboelastography (TEG) and thromboelastometry (ROTEM) are increasingly used to guide transfusion strategy but their roles remain disputed. This review was first published in 2011 and updated in January 2016.

OBJECTIVES

We assessed the benefits and harms of thromboelastography (TEG)-guided or thromboelastometry (ROTEM)-guided transfusion in adults and children with bleeding. We looked at various outcomes, such as overall mortality and bleeding events, conducted subgroup and sensitivity analyses, examined the role of bias, and applied trial sequential analyses (TSAs) to examine the amount of evidence gathered so far.

SEARCH METHODS

In this updated review we identified randomized controlled trials (RCTs) from the following electronic databases: Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 1); MEDLINE; Embase; Science Citation Index Expanded; International Web of Science; CINAHL; LILACS; and the Chinese Biomedical Literature Database (up to 5 January 2016). We contacted trial authors, authors of previous reviews, and manufacturers in the field. The original search was run in October 2010.

SELECTION CRITERIA

We included all RCTs, irrespective of blinding or language, that compared transfusion guided by TEG or ROTEM to transfusion guided by clinical judgement, guided by standard laboratory tests, or a combination. We also included interventional algorithms including both TEG or ROTEM in combination with standard laboratory tests or other devices. The primary analysis included trials on TEG or ROTEM versus any comparator.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted data; we resolved any disagreements by discussion. We presented pooled estimates of the intervention effects on dichotomous outcomes as risk ratio (RR) with 95% confidence intervals (CIs). Due to skewed data, meta-analysis was not provided for continuous outcome data. Our primary outcome measure was all-cause mortality. We performed subgroup and sensitivity analyses to assess the effect based on the presence of coagulopathy of a TEG- or ROTEM-guided algorithm, and in adults and children on various clinical and physiological outcomes. We assessed the risk of bias through assessment of trial methodological components and the risk of random error through TSA.

MAIN RESULTS

We included eight new studies (617 participants) in this updated review. In total we included 17 studies (1493 participants). A total of 15 trials provided data for the meta-analyses. We judged only two trials as low risk of bias. The majority of studies included participants undergoing cardiac surgery.We found six ongoing trials but were unable to retrieve any data from them. Compared with transfusion guided by any method, TEG or ROTEM seemed to reduce overall mortality (7.4% versus 3.9%; risk ratio (RR) 0.52, 95% CI 0.28 to 0.95; I(2) = 0%, 8 studies, 717 participants, low quality of evidence) but only eight trials provided data on mortality, and two were zero event trials. Our analyses demonstrated a statistically significant effect of TEG or ROTEM compared to any comparison on the proportion of participants transfused with pooled red blood cells (PRBCs) (RR 0.86, 95% CI 0.79 to 0.94; I(2) = 0%, 10 studies, 832 participants, low quality of evidence), fresh frozen plasma (FFP) (RR 0.57, 95% CI 0.33 to 0.96; I(2) = 86%, 8 studies, 761 participants, low quality of evidence), platelets (RR 0.73, 95% CI 0.60 to 0.88; I(2) = 0%, 10 studies, 832 participants, low quality of evidence), and overall haemostatic transfusion with FFP or platelets (low quality of evidence). Meta-analyses also showed fewer participants with dialysis-dependent renal failure.We found no difference in the proportion needing surgical reinterventions (RR 0.75, 95% CI 0.50 to 1.10; I(2) = 0%, 9 studies, 887 participants, low quality of evidence) and excessive bleeding events or massive transfusion (RR 0.38, 95% CI 0.38 to 1.77; I(2) = 34%, 2 studies, 280 participants, low quality of evidence). The planned subgroup analyses failed to show any significant differences.We graded the quality of evidence as low based on the high risk of bias in the studies, large heterogeneity, low number of events, imprecision, and indirectness. TSA indicates that only 54% of required information size has been reached so far in regards to mortality, while there may be evidence of benefit for transfusion outcomes. Overall, evaluated outcomes were consistent with a benefit in favour of a TEG- or ROTEM-guided transfusion in bleeding patients.

AUTHORS' CONCLUSIONS

There is growing evidence that application of TEG- or ROTEM-guided transfusion strategies may reduce the need for blood products, and improve morbidity in patients with bleeding. However, these results are primarily based on trials of elective cardiac surgery involving cardiopulmonary bypass, and the level of evidence remains low. Further evaluation of TEG- or ROTEM-guided transfusion in acute settings and other patient categories in low risk of bias studies is needed.

A critical appraisal of point-of-care coagulation testing in critically ill patients

Derangement of the coagulation system is a common phenomenon in critically ill patients, who may present with severe bleeding and/or conditions associated with a prothrombotic state. Monitoring of this coagulopathy can be performed with conventional coagulation assays; however, point-of-care tests have become increasingly attractive, because not only do they yield a more rapid result than clinical laboratory testing, but they may also provide a more complete picture of the condition of the hemostatic system. There are many potential areas of study and applications of point-of-care hemostatic testing in critical care, including patients who present with massive blood loss, patients with a hypercoagulable state (such as in disseminated intravascular coagulation), and monitoring of antiplatelet treatment for acute arterial thrombosis, mostly acute coronary syndromes. However, the limitations of near-patient hemostatic testing has not been fully appreciated, and are discussed here. The currently available evidence indicates that point-of-care tests may be applied to guide appropriate blood product transfusion and the use of hemostatic agents to correct the hemostatic defect or to ameliorate antithrombotic treatment. Disappointingly, however, only in cardiac surgery is there adequate evidence to show that application of near-patient thromboelastography leads to an improvement in clinically relevant outcomes, such as reductions in bleeding-related morbidity and mortality, and cost-effectiveness. More research is required to validate the utility and cost-effectiveness of near-patient hemostatic testing in other areas, especially in traumatic bleeding and postpartum hemorrhage.

Can the Viscoelastic Parameter α-Angle Distinguish Fibrinogen from Platelet Deficiency and Guide Fibrinogen Supplementation?

Viscoelastic tests such as thrombelastography (TEG, Haemoscope Inc., Niles, IL) and thromboelastometry (ROTEM, Tem International GmbH, Munich, Germany), performed in whole blood, are increasingly used at the point-of-care to characterize coagulopathic states and guide hemostatic therapy. An algorithm, based on a mono-analysis (kaolin-activated assay) approach, was proposed in the TEG patent (issued in 2004) where the α-angle and the maximum amplitude parameters are used to guide fibrinogen supplementation and platelet administration, respectively. Although multiple assays for both the TEG and ROTEM devices are now available, algorithms based on TEG mono-analysis are still used in many institutions. In light of more recent findings, we discuss here the limitations and inaccuracies of the mono-analysis approach. Research shows that both α-angle and maximum amplitude parameters reflect the combined contribution of fibrinogen and platelets to clot strength. Therefore, although TEG mono-analysis is useful for identifying a coagulopathic state, it cannot be used to discriminate between fibrin/fibrinogen and/or platelet deficits, respectively. Conversely, the use of viscoelastic methods where 2 assays can be run simultaneously, one with platelet inhibitors and one without, can effectively allow for the identification of specific coagulopathic states, such as insufficient fibrin formation or an insufficient contribution of platelets to clot strength. Such information is critical for making the appropriate choice of hemostatic therapy.

Hemostatic resuscitation in postpartum hemorrhage - a supplement to surgery

BACKGROUND

Postpartum hemorrhage is a potentially life-threatening albeit preventable condition that persists as a leading cause of maternal death. Identification of safe and cost-effective hemostatic treatment options remains crucial as a supplement to surgery and uterotonic agents.

OBJECTIVE

This review summarizes the background, current evidence and recommendations with regard to the role of fibrinogen, tranexamic acid, prothrombin complex concentrate, desmopressin, and recombinant factor VIIa in the treatment of patients with postpartum hemorrhage. The benefits and evidence behind traditional standard laboratory tests and viscoelastic hemostatic assays, i.e. thromboelastography TEG(®) and thromboelastometry ROTEM(®) , are discussed. In addition we assess and elaborate on the current paradigm and evidence for transfusion of these patients.

DATA SOURCES

Publications between 1994 and 2014 were identified from PubMed, EMBASE, Cochrane Library databases, and ClinicalTrial.gov.

RESULTS

Viscoelastic hemostatic assays were found to provide a real-time continuum of coagulation and fibrinolysis when introduced as a supplement in transfusion management of postpartum hemorrhage. Fibrinogen should be considered when hypofibrinogenemia is identified. Early administration of 1-2 g tranexamic acid is recommended, followed by an additional dose in cases of ongoing bleeding. Uncontrolled hemorrhage requires early balanced transfusion.

CONCLUSION

Despite the lack of conclusive evidence for optimal hemostatic resuscitation in postpartum hemorrhage, the use of viscoelastic hemostatic assays, fibrinogen, tranexamic acid and balanced transfusion therapy may prove to be potentially pivotal in the treatment of postpartum hemorrhage.

Transfusion ratios for postpartum hemodilutional coagulopathy: an in vitro thromboelastographic model

OBJECTIVE

A 1:1:1 ratio of packed red blood cells (PRBC), fresh frozen plasma (FFP), and platelets (PLT) has been advocated for trauma hemorrhage, but the effectiveness of this ratio for postpartum hemorrhage is unknown. We created an in vitro hemodilutional model to investigate this strategy.

STUDY DESIGN

Blood from 20 parturients at term was diluted 50% with 0.9% normal saline. Diluted samples were reconstituted with 1:1 PRBC:FFP or 3:1 PRBC:FFP. In 10 samples, PLT were also added. Baseline, diluted, and reconstituted sample thromboelastographic values were compared.

RESULTS

Maximum amplitude (MA) was lower compared to baseline values in both groups after 50% dilution with normal saline (P < .001) and remained lower than baseline despite reconstitution with 3:1:0 or 1:1:0 PRBC:FFP:PLT (P < .0001) or 3:1:1 PRBC:FFP:PLT (P < .01). MA approached baseline (P = not significant) in the samples with 1:1:1 PRBC:FFP:PLT.

CONCLUSION

The addition of PLT to 1:1 PRBC:FFP optimized MA in this in vitro hemodilutional model of postpartum hemorrhage.

How we manage the haematological aspects of major obstetric haemorrhage

Major obstetric haemorrhage (MOH) remains an important medical challenge worldwide, contributing to significant maternal morbidity and mortality. Prompt and appropriate management is essential if we are to improve outcomes and reduce substandard care that may result in adverse consequences. This review describes the current understanding of the pathophysiological aspects of MOH together with the principles of transfusion and haemostatic therapy, with emphasis on a coordinated multidisciplinary approach. We also highlight the current lack of evidence available from randomized controlled trials to inform best practice and the need to prioritize research in this key clinical area.

Postpartum hemorrhage: the role of the Maternal-Fetal Medicine specialist in enhancing quality and patient safety

Postpartum hemorrhage in excess of 1000 mL affects 2.9-4.3% of deliveries in North America and the prevalence is increasing (Calvert et al., 2012(1); Callaghan et al., 2010(2)). Given the unpredictable nature of most postpartum hemorrhages, all obstetric providers must understand the initial steps in the assessment and management of this emergency. In this monograph we will review the potential role of the Maternal-Fetal Medicine (MFM) specialist in managing this acute obstetric emergency. MFMs are uniquely positioned to develop hospital protocols, advocate for investment in resources to optimize outcomes, and utilize novel educational models, such as simulation, to educate other providers on the recognition and management of this condition. MFMs can also aid in the antepartum diagnosis of abnormal placentation, which is an increasingly common risk factor for severe hemorrhage.