Viscoelastic point-of-care testing to assist with the diagnosis, management and monitoring of haemostasis: a systematic review and cost-effectiveness analysis

Strategies to prevent blood loss and reduce transfusion in emergency general surgery, WSES-AAST consensus paper

Emergency general surgeons often provide care to severely ill patients requiring surgical interventions and intensive support. One of the primary drivers of morbidity and mortality is perioperative bleeding. In general, when addressing life threatening haemorrhage, blood transfusion can become an essential part of overall resuscitation. However, under all circumstances, indications for blood transfusion must be accurately evaluated. When patients decline blood transfusions, regardless of the reason, surgeons should aim to provide optimal care and respect and accommodate each patient's values and target the best outcome possible given the patient's desires and his/her clinical condition. The aim of this position paper was to perform a review of the existing literature and to provide comprehensive recommendations on organizational, surgical, anaesthetic, and haemostatic strategies that can be used to provide optimal peri-operative blood management, reduce, or avoid blood transfusions and ultimately improve patient outcomes.

Viscoelastic Testing in an Obstetric Population at High Risk of Hemorrhage

INTRODUCTION

Rotational thromboelastometry (ROTEM) is a point-of-care viscoelastic test used in trauma for goal-directed transfusion. However, there are limited data on baseline ROTEM parameters in the U.S. obstetric population. Obtaining baseline parameters is a first step in implementing a goal-directed massive transfusion protocol in obstetric hemorrhage.

OBJECTIVE

Our study aimed to establish pre- and postdelivery baseline parameters in a high-risk obstetric population and determine their association with postpartum hemorrhage (PPH).

STUDY DESIGN

Prospective observational study of patients ≥34 weeks' gestation, at high risk of PPH, admitted for delivery. INTEM, EXTEM, FIBTEM, and APTEM assays were performed at the time of admission to labor and delivery and then 2 hours after delivery. Primary outcome was pre- and postdelivery ROTEM parameters among women without PPH. A sample size of 60 women was needed for >90% power to detect at least 50% correlation between pre- and postdelivery assuming a loss of 10% of participants to follow-up.

RESULTS

Of 60 women in the study, 10 (17%) had PPH. Baseline characteristics were not different between those with or without PPH. Pre- and postdelivery ROTEM parameters were not significantly different except for APTEM. None of the patients who had PPH, compared with 4 (10%) of those who did not, had shortened clotting time and higher maximum clot firmness in postdelivery APTEM compared with EXTEM, a pattern suggestive of hyperfibrinolysis (p = 0.4).

CONCLUSION

In this study, we describe baseline ROTEM parameters in women at high risk of PPH. The majority of patients did not have a ROTEM pattern that is suggestive of hyperfibrinolysis, for which tranexamic acid is thought to be beneficial. Based on our findings, previously established obstetric transfusion thresholds for goal-directed massive transfusion protocols are likely valid for the majority of the obstetric population regardless of the presence of comorbidities or pregnancy complications.

KEY POINTS

· ROTEM parameters do not vary significantly before and after delivery.. · Most patients did not have a hyperfibrinolysis pattern, for which tranexamic acid is thought to be beneficial.. · Previous goal-directed obstetric transfusion thresholds are likely valid in most populations..

Thromboelastography-Guided Correction of Coagulopathy Before Tunneled Central Venous Access in Critically Ill Patients With Liver Disease: A Propensity Score-Matched Study

Importance

Optimal blood product transfusion strategies before tunneled central venous catheter (CVC) placement are required in critically ill coagulopathic patients with liver disease to reduce exposure to allogeneic blood products and mitigate bleeding and thrombotic complications.

Objectives

This study evaluated the safety and efficacy of a thromboelastography-guided transfusion strategy for the correction of coagulopathy in patients with liver disease compared with a conventional transfusion strategy (using international normalized ratio, platelet count, and fibrinogen) before tunneled CVC insertion.

Design Setting and Participants

A retrospective propensity score-matched single-center cohort study was conducted at a quaternary care academic medical center involving 364 patients with liver disease (cirrhosis and acute liver failure) who underwent tunneled CVC insertion in the ICU. Patients were stratified into two groups based on whether they received blood product transfusions based on a thromboelastography-guided or conventional transfusion strategy.

Main Outcomes and Measures

Primary outcomes that were evaluated included the volume, units and cost of blood products (fresh frozen plasma, cryoprecipitate, and platelets) when using a thromboelastography-guided or conventional approach to blood transfusions. Secondary outcomes included the frequency of procedure-related bleeding and thrombotic complications.

Results

The total number of units/volume/cost of fresh frozen plasma (12 U/3,000 mL/$684 vs. 32 U/7,500 mL/$1,824 [p = 0.019]), cryoprecipitate (60 U/1,500 mL/$3,240 vs. 250 U/6,250 mL/$13,500 [p < 0.001]), and platelets (5 U/1,500 mL/$2,610 vs. 13 units/3,900 mL/$6,786 [p = 0.046]) transfused were significantly lower in the thromboelastography-guided transfusion group than in the conventional transfusion group. No differences in the frequency of bleeding/thrombotic events were observed between the two groups.

Conclusions and Relevance

A thromboelastography-guided transfusion strategy for correction of coagulopathy in critically ill patients with liver disease before tunneled CVC insertion, compared with a conventional transfusion strategy, reduces unnecessary exposure to allogeneic blood products and associated costs without increasing the risk for peri-procedural bleeding and thrombotic complications.

Viscoelastic Testing Methods

Viscoelastic testing methods examine the real-time formation of a clot in a whole blood sample, and include thromboelastography (TEG), rotational thromboelastometry (ROTEM), and several other testing platforms. They allow for concurrent assessment of multiple aspects of clotting, including plasmatic coagulation factors, platelets, fibrinogen, and the fibrinolytic pathway. This testing is rapid and may be performed at the point-of-care, allowing for prompt identification of coagulopathies to guide focused and rational administration of blood products as well as the identification of anticoagulant effect. With recent industry progression towards user-friendly, cartridge-based, portable instruments, viscoelastic testing has emerged in the 21st century as a powerful tool to guide blood transfusions in the bleeding patient, and to identify and treat both bleeding and thrombotic conditions in many operative settings, including trauma surgery, liver transplant surgery, cardiac surgery, and obstetrics. In these settings, the use of transfusion algorithms guided by viscoelastic testing data has resulted in widespread improvements in patient blood management as well as modest improvements in select patient outcomes. To address the increasingly wide adoption of viscoelastic methods and the growing number of medical and laboratory personnel tasked with implementing, performing, and interpreting these methods, this chapter provides an overview of the history, physiology, and technology behind viscoelastic testing, as well as a practical review of its clinical utility and current evidence supporting its use. Also included is a review of testing limitations and the contextual role played by viscoelastic methods among all coagulation laboratory testing.

Amplified inhibition of atherosclerotic plaque-induced platelet activation by glenzocimab with dual antiplatelet therapy

BACKGROUND

Aspirin and platelet P2Y12 inhibitors, such as ticagrelor, suboptimally inhibit microvascular thrombosis during ST-elevation myocardial infarction. Glycoprotein (GP) IIb/IIIa inhibitors may further inhibit this but cause excessive bleeding.

OBJECTIVES

We investigated whether combination of glenzocimab, a GPVI inhibitor, with aspirin and ticagrelor provides additional antithrombotic effects, as GPVI has a critical role in atherothrombosis but minimal involvement in hemostasis.

METHODS

We investigated the effects of glenzocimab (monoclonal antibody Fab fragment) using blood from healthy donors and patients with acute coronary syndrome treated with aspirin and ticagrelor. Platelets were stimulated with multiple agonists, including atherosclerotic plaque, from patients undergoing carotid endarterectomy.

RESULTS

Aspirin and ticagrelor partially inhibited atherosclerotic plaque-induced platelet aggregation by 48% compared with control (34 ± 3 vs 65 ± 4 U; P < .001). Plaque-induced platelet aggregation, adhesion, secretion, and activation were critically dependent on GPVI activation. Glenzocimab alone reduced plaque-induced aggregation by 75% compared with control (16 ± 4 vs 65 ± 4 U; P < .001) and by >95% when combined with aspirin and ticagrelor (3 ± 1 vs 65 ± 4 U; P < .001). Glenzocimab reduced platelet aggregation, adhesion, and thrombin generation when added to blood of aspirin- and ticagrelor-treated patients with acute coronary syndrome. Glenzocimab shared several antithrombotic effects with the GPIIb/IIIa inhibitor eptifibatide with less effect on general hemostasis assessed by rotational thromboelastometry. In a murine intravital model of ST-elevation myocardial infarction, genetic depletion of GPVI reduced microvascular thrombosis.

CONCLUSION

Addition of glenzocimab to aspirin and ticagrelor enhances platelet inhibition via multiple mechanisms of atherothrombosis. Compared with a GPIIb/IIIa inhibitor, glenzocimab shares multiple antithrombotic effects, with less inhibition of mechanisms involved in general hemostasis.

Platelet Function Testing Using Sonoclot and TEG6s as a Platelet Transfusion Prediction Tool in Open Heart Surgery

Introduction The point-of-care test (POCT) is useful for blood coagulation management during cardiovascular surgery. Although thromboelastography (TEG6s) has been reported to have targeted benefits for blood transfusion in cardiac surgery, Sonoclot analysis has not yet been fully validated. In this study, we evaluated the accuracy of Sonoclot, especially platelet function (PF) as a platelet concentrate (PC) transfusion parameter, compared to TEG6s in cardiovascular surgery. Methods This single-center, prospective, randomised trial was conducted at a university hospital. Forty-two adult patients who underwent elective cardiac surgery requiring cardiopulmonary bypass were included in this study between 2017 and 2021. The participants were randomly assigned to the Sonoclot (S) or Sonoclot and TEG6s (ST) groups. The amount of intraoperative PC was determined according to the POCT parameter values at the time of protamine administration. In addition, we investigated the correlation between PF parameters of POCT and platelet count at the end of surgery. Results There was no statistically significant difference in the intraoperative PC volume between the two groups. The Sonoclot PF parameter, PF, was moderately correlated with platelet count at the end of surgery (r=0.5449, p=0.009), and the TEG6s PF parameter showed a strong correlation with platelet count at the end of surgery (r=0.7744, p<0.001). Conclusion There was no statistically significant difference in platelet transfusion volume between the Sonoclot and TEG6s in this study. The correlation between the PF of the Sonoclot and platelet count was moderate. This study suggests that PF of Sonoclot may be a potentiating indicator of PF.

TEG-based transfusion protocol is associated with decreased blood product use without increased risk of hemoperitoneum

BACKGROUND

Thromboelastography (TEG) informs the need for blood product transfusions to prevent procedural bleeding complications in patients with cirrhosis. We aimed to evaluate the impact of using a TEG-based transfusion protocol on blood product utilization before paracentesis and the post-paracentesis hemoperitoneum (PPH) incidence.

METHODS

We conducted an ambispective analysis of patients with cirrhosis who underwent paracentesis from 2017 to 2021. In May 2019, we enacted a TEG-based transfusion protocol to guide pre-paracentesis blood product use. Patients with platelets < 20,000 or international normalized ratio ≥ 4 underwent TEG and received blood products if r value > 10 min or MA <30 mm. Patients were divided into pre-TEG and post-TEG protocol cohorts based on the date of paracentesis. Pre-paracentesis blood product transfusions in the form of platelets, fresh frozen plasma, and cryoprecipitates were recorded. PPH was defined as a decrease in hemoglobin of ≥1 g and the presence of blood on diagnostic imaging and/or the need for therapeutic intervention.

RESULTS

A total of 483 patients underwent 1281 paracenteses. The main etiologies of cirrhosis were alcohol (43%) and NASH (25%), and the mean MELD-sodium was 22±6. Pre-TEG and post-TEG protocol cohort sizes were similar: 253 patients and 607 paracenteses versus 230 patients and 674 paracenteses. After TEG-protocol implementation, blood product transfusions decreased significantly (228 vs. 49 products, p<0.001) with associated cost savings. One patient in each cohort developed PPH.

CONCLUSION

Implementation of a pre-paracentesis TEG-based transfusion protocol for patients with cirrhosis successfully resulted in decreased blood product use with no associated increase in incidence of PPH.

Viscoelastic testing: Critical appraisal of new methodologies and current literature

United States Food and Drug Administration (FDA)-approved viscoelastic testing (VET) methodologies have significantly changed in the last 10 years, with the availability of cartridge-based VET. Some of these cartridge-based methodologies use harmonic resonance-based clot detection. While VET has always allowed for the evaluation of real-time clot formation, cartridge-based VET provides increased ease of use as well as greater portability and robustness of results in out-of-laboratory environments. Here we review the use of VET in a variety of clinical contexts, including cardiac surgery, trauma, liver transplant, obstetrics, and hypercoagulable states such as COVID-19. As of now, high quality randomized trial evidence for new generation VET (TEG 6s, HemoSonics Quantra, ROTEM sigma) is limited. Nevertheless, the use of VET-guided transfusion algorithms appears to result in reduced blood usage without worsening of patient outcomes. Future work comparing the new generation VET instruments and continuing to validate clinically important cut-offs will help move the field of point-of-care coagulation monitoring forward and increase the quality of transfusion management in bleeding patients.

[Viscoelasticity-based point of care coagulation diagnostics in the context of resuscitation room management of severely injured and bleeding trauma patients : Diagnostics and treatment of trauma-induced coagulopathy]

Uncontrolled bleeding with associated trauma-induced coagulopathy (TIC) remains the leading cause of preventable death after severe trauma. Meanwhile, TIC is recognized as a separate clinical entity with substantial impact on downstream morbidity and mortality. In clinical practice severely injured and bleeding patients are often still being treated according to established damage control surgery (DCS) procedures with surgical bleeding control and empirical transfusion of classical blood products in predefined ratios in the sense of damage control resuscitation (DCR); however, algorithms are also available, which have been constructed from established viscoelasticity-based point of care (POC) diagnostic procedures and target value-oriented treatments. The latter enables a timely qualitative assessment of coagulation function from whole blood at bedside and provides rapid and clinically useful information on the presence, development and dynamics of the coagulation disorder. The early implementation of viscoelasticity-based POC procedures in the context of resuscitation room management of severely injured and bleeding patients was uniformly associated with reductions in potentially harmful blood products, especially overtransfusions, and an overall improvement in outcome including survival. The present article reviews the clinical questions around the use of viscoelasticity-based procedures as well as recommendations for the early and acute management of bleeding trauma patients taking the current literature into account.

A Systematic Review of Viscoelastic Testing in Patients with Subarachnoid Hemorrhage

OBJECTIVE

Bleeding and thromboembolic complications frequently occur after subarachnoid hemorrhage (SAH) and substantially contribute to poor outcome. Viscoelastic testing could be used for detection of coagulopathies after SAH. This review summarizes literature on the usefulness of viscoelastic testing to detect coagulopathy in patients with SAH and explores whether viscoelastic parameters are associated with SAH-related complications and clinical outcome.

METHODS

PubMed, Embase, and Google Scholar were systematically searched on August 18, 2022. Two authors independently selected studies that reported viscoelastic testing in patients with SAH and assessed the quality of studies using the Newcastle-Ottawa Scale or a previously reported framework for quality assessment. Data were meta-analyzed if methodologically possible.

RESULTS

The search yielded 19 studies (1160 patients with SAH). Pooling of data including all relevant studies was not possible for any of the outcome measurements because of methodological differences. Thirteen of 19 studies evaluated the association of coagulation profiles and SAH, of which 11 studies showed a hypercoagulable profile. Rebleeding was associated with platelet dysfunction, deep venous thrombosis was associated with faster clot initiation, and both delayed cerebral ischemia and poor outcome were associated with increased clot strength.

CONCLUSIONS

This explorative review shows that patients with SAH frequently have a hypercoagulable profile. Thromboelastography (TEG) and rotational thromboelastometry (ROTEM) parameters are associated with rebleeding, delayed cerebral ischemia, deep venous thrombosis, and poor clinical outcome after SAH; however, more research on the subject is needed. Future studies should focus on determining the optimal time frame and cutoff values for TEG or ROTEM to predict these complications.

Patient Blood Management in Liver Transplant—A Concise Review

Transfusion of blood products in orthotopic liver transplantation (OLT) significantly increases post-transplant morbidity and mortality and is associated with reduced graft survival. Based on these results, an active effort to prevent and minimize blood transfusion is required. Patient blood management is a revolutionary approach defined as a patient-centered, systematic, evidence-based approach to improve patient outcomes by managing and preserving a patient’s own blood while promoting patient safety and empowerment. This approach is based on three pillars of treatment: (1) detecting and correcting anemia and thrombocytopenia, (2) minimizing iatrogenic blood loss, detecting, and correcting coagulopathy, and (3) harnessing and increasing anemia tolerance. This review emphasizes the importance of the three-pillar nine-field matrix of patient blood management to improve patient outcomes in liver transplant recipients.

The European guideline on management of major bleeding and coagulopathy following trauma: sixth edition

BACKGROUND

Severe trauma represents a major global public health burden and the management of post-traumatic bleeding continues to challenge healthcare systems around the world. Post-traumatic bleeding and associated traumatic coagulopathy remain leading causes of potentially preventable multiorgan failure and death if not diagnosed and managed in an appropriate and timely manner. This sixth edition of the European guideline on the management of major bleeding and coagulopathy following traumatic injury aims to advise clinicians who care for the bleeding trauma patient during the initial diagnostic and therapeutic phases of patient management.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma included representatives from six European professional societies and convened to assess and update the previous version of this guideline using a structured, evidence-based consensus approach. Structured literature searches covered the period since the last edition of the guideline, but considered evidence cited previously. The format of this edition has been adjusted to reflect the trend towards concise guideline documents that cite only the highest-quality studies and most relevant literature rather than attempting to provide a comprehensive literature review to accompany each recommendation.

RESULTS

This guideline comprises 39 clinical practice recommendations that follow an approximate temporal path for management of the bleeding trauma patient, with recommendations grouped behind key decision points. While approximately one-third of patients who have experienced severe trauma arrive in hospital in a coagulopathic state, a systematic diagnostic and therapeutic approach has been shown to reduce the number of preventable deaths attributable to traumatic injury.

CONCLUSION

A multidisciplinary approach and adherence to evidence-based guidelines are pillars of best practice in the management of severely injured trauma patients. Further improvement in outcomes will be achieved by optimising and standardising trauma care in line with the available evidence across Europe and beyond.

Interaction Between Platelet and Fibrinogen on Clot Strength in Healthy Patients

OBJECTIVE

The purpose of this study was to explore the relationship between platelet concentration (PLT) (× 10⁹/L) and clot strength measured by thromboelastography maximum amplitude (TEG-MA) in healthy volunteers without a history of coagulation abnormalities. Secondarily, the relationship between fibrinogen (mg/dL) and TEG-MA was analyzed.

DESIGN

A prospective study.

SETTING

At a university's tertiary-care center.

MEASUREMENTS AND MAIN RESULTS

Using whole blood, PLT was reduced in the first part, and hematocrit was reduced in the second part of the study by hemodilution with platelet-rich and -poor plasma. Thromboelastography (TEG 5000 Haemonetics) was performed to measure clot formation and strength. Spearman correlation coefficients regression analyses and receiver-operating characteristics (ROC) were obtained to analyze the relationships among PLT, fibrinogen, and TEG-MA. Strong correlations were found in univariate analysis between PLT and TEG-MA (r = 0.88; p < 0.0001) and between Fibrinogen and TEG-MA (r = 0.70; p = 0.003). A biphasic relationship between PLT and TEG-MA was linear below a PLT 90 × 10⁹/L, followed by a plateau above 100 × 10⁹/L (p = 0.001). A linear relationship between fibrinogen (190-474 mg/dL) and TEG-MA (53-76 mm) was found (p = 0.0007). The ROC analysis found that PLT = 60 × 10⁹/L was associated with a TEG-MA of 53.0 mm. The product of PLT and fibrinogen concentrations was more strongly correlated (r = 0.91) to TEG-MA than either PLT (r = 0.86) or fibrinogen (r = 0.71) alone. A ROC analysis revealed that a TEG-MA of 55 mm was associated with a PLT × fibrinogen of 16,720.

CONCLUSION

In healthy patients, a PLT of 60 × 10⁹/L was associated with normal clot strength (TEG-MA ≥53 mm), and there was little change in clot strength with PLT >90 × 10⁹/L. Although prior analyses described the contributions of platelets and fibrinogen toward clot strength, they are presented and discussed independently. The data above described clot strength as an interaction among them. Future analyses and clinical care should evaluate and recognize the interplay.

Emerging technology for early detection and management of postpartum hemorrhage to prevent morbidity

Despite advances in hemorrhage detection and management, postpartum hemorrhage remains the single leading cause of maternal death worldwide. Within the United States, hemorrhage is the leading cause of maternal death on the day of delivery and within the first week after delivery. Blood transfusion after hemorrhage represents a large proportion of severe maternal morbidity during and after delivery. Blood loss during delivery has historically been assessed visually by inspecting soiled pads, linens, and laparotomy sponges. These methods underestimate the volume of blood loss by as much as 40%, becoming increasingly inaccurate as blood loss increases. Young, healthy obstetrical patients compensate for blood loss via peripheral vasoconstriction, maintaining heart rate and blood pressure in a normal range until over 1 L of blood has been lost. A significant decrease in blood pressure along with marked tachycardia (>120 bpm) may not be seen until 30% to 40% of blood volume has been lost, or 2.0 to 2.6 L in a healthy term pregnant patient, after which the patient may rapidly decompensate. In resource-poor settings especially, the narrow window between the emergence of significant vital sign abnormalities and clinical decompensation may prove catastrophic. Once hemorrhage is detected, decisions regarding blood product transfusion are routinely made on the basis of inaccurate estimates of blood loss, placing patients at risk of underresuscitation (increasing the risk of hemorrhagic shock and end-organ damage) or overresuscitation (increasing the risk of transfusion reaction, fluid overload, and alloimmunization). We will review novel technologies that have emerged to assist both in the early and accurate detection of postpartum hemorrhage and in decisions regarding blood product transfusion.

Current and future strategies to monitor and manage coagulation in ECMO patients

Extracorporeal membrane oxygenation (ECMO) can provide life-saving support for critically ill patients suffering severe respiratory and/or cardiac failure. However, thrombosis and bleeding remain common and complex problems to manage. Key causes of thrombosis in ECMO patients include blood contact to pro-thrombotic and non-physiological surfaces, as well as high shearing forces in the pump and membrane oxygenator. On the other hand, adverse effects of anticoagulant, thrombocytopenia, platelet dysfunction, acquired von Willebrand syndrome, and hyperfibrinolysis are all established as causes of bleeding. Finding safe and effective anticoagulants that balance thrombosis and bleeding risk remains challenging. This review highlights commonly used anticoagulants in ECMO, including their mechanism of action, monitoring methods, strengths and limitations. It further elaborates on existing anticoagulant monitoring strategies, indicating their target range, benefits and drawbacks. Finally, it introduces several highly novel approaches to real-time anticoagulation monitoring methods including sound, optical, fluorescent, and electrical measurement as well as their working principles and future directions for research.

The role of point of care thromboelastography (TEG) and thromboelastometry (ROTEM) in management of Primary postpartum haemorrhage: A meta-analysis and systematic review

Background

The utility of instantaneous evaluation of coagulation during primary postpartum haemorrhage (PPH) is paramount in the context of empirical blood product transfusion-related risk of dilutional and consumptive coagulopathy and circulatory overload.

Methods

A profound screening of electronic databases till August 15, 2022 was carried out after being enlisted in PROSPERO (CRD42021275514). Randomized control studies, comparative cohort studies, and cross-sectional studies comparing point-of-care viscoelastic test guided blood product transfusion with empirical transfusion in patients with PPH were included.

Results

We retrieved five studies, with a total of 1914 parturient with PPH. Patients receiving transfusion based upon point of care viscoelastic tests had lesser risk of having emergency hysterectomy (Odds ratio (OR) = 0.55, 95% CI 0.32-0.95, I2 = 7%), transfusion-associated circulatory overload (TACO) (OR = 0.03, 95% CI 0.00-0.50), reduced transfusion of fresh frozen plasma (OR = 0.07, 95% CI 0.04-0.14, I2 = 89%), platelets (OR = 0.51, 95% CI 0.28-0.91, I2 = 89%), packed red blood cell transfusion (OR = 0.70, 95% CI 0.55-0.88, I2 = 89%), and had better cost-effective treatment [Mean difference (MD) = -357.5, 95% CI - 567.75 to -147.25, I2 = 93%] than patient received empirical transfusion. However, there was no significant difference in the requirement of ICU admissions (OR = 0.77, 95% CI = 0.46-1.29, I2 = 82%). No mortality was detected across the studies.

Conclusions

Point of care viscoelastic assessment guided transfusion in PPH confederates with reduced morbidity. Nevertheless, more studies on the triggering values for transfusion, long-term survival, and cost-benefit in patients with PPH are warranted to establish its utility.

Systematic reviews on platelet transfusions: Is there unnecessary duplication of effort? A scoping review

BACKGROUND AND OBJECTIVES

Platelet transfusions are used across multiple patient populations to prevent and correct bleeding. This scoping review aimed to map the currently available systematic reviews (SRs) and evidence-based guidelines in the field of platelet transfusion.

MATERIALS AND METHODS

A systematic literature search was conducted in seven databases for SRs on effectiveness (including dose and timing, transfusion trigger and ratio to other blood products), production modalities and decision support related to platelet transfusion. The following data were charted: methodological features of the SR, population, concept and context features, outcomes reported, study design and number of studies included. Results were synthesized in interactive evidence maps.

RESULTS

We identified 110 SRs. The majority focused on clinical effectiveness, including prophylactic or therapeutic transfusions compared to no platelet transfusion (34 SRs), prophylactic compared to therapeutic-only transfusion (8 SRs), dose, timing (11 SRs) and threshold for platelet transfusion (15 SRs) and the ratio of platelet transfusion to other blood products in massive transfusion (14 SRs). Furthermore, we included 34 SRs on decision support, of which 26 evaluated viscoelastic testing. Finally, we identified 22 SRs on platelet production modalities, including derivation (4 SRs), pathogen inactivation (6 SRs), leucodepletion (4 SRs) and ABO/human leucocyte antigen matching (5 SRs). The SRs were mapped according to concept and clinical context.

CONCLUSION

An interactive evidence map of SRs and evidence-based guidelines in the field of platelet transfusion has been developed and identified multiple reviews. This work serves as a tool for researchers looking for evidence gaps, thereby both supporting research and avoiding unnecessary duplication.

Global Coagulation Testing in Acute Care Medicine: Back to Bedside?

OBJECTIVES

 Detailed and decisive information about the patients' coagulation status is important in various emergency situations. Conventional global coagulation testing strategies are often used to provide a quick overview, but several limitations particularly in the trauma setting are well described. With the introduction of direct oral anticoagulations (DOACs), a milestone for several disease entities resulting in overall improved outcomes could be reached, but at the same time providing new diagnostic challenges for the emergency situation.

DESIGN

 As an alternative to conventional coagulation tests, there is increasing clinical and scientific interest in the use of early whole blood strategies to provide goal-directed coagulation therapies (GDCT) and hemostatic control in critically ill patients. Viscoelastic hemostatic assays (VHAs) were therefore introduced to several clinical applications and may provide as a bedside point-of-care method for faster information on the underlying hemostatic deficiency.

CONCLUSION

 The use of VHA-based algorithms to guide hemostatic control in emergency situations now found its way to several international guidelines for patients at risk of bleeding. With this qualitative review, we would like to focus on VHA-based GDCT and review the current evidence for its use, advantages, and challenges in the two different clinical scenarios of trauma and intracerebral bleeding/stroke management.

Patient Blood Management in Vascular Surgery

Patient blood management (PBM) is an evidence-based, multidisciplinary approach aimed at appropriately allocating blood products to patients requiring transfusion while simultaneously minimizing inappropriate transfusions. The 3 pillars of patient blood management are optimizing erythropoiesis, minimizing blood loss, and optimizing physiological reserve of anemia. Benefits seen from PBM include limiting hospital costs and mitigating harm from numerous risks of transfusion.

Storage of packed red blood cells impairs an inherent coagulation property of erythrocytes

Storage of packed red blood cells is associated with changes in erythrocytes that over time increasingly impair cellular function and potentially contribute to adverse effects associated with blood transfusion. Exposure of phosphatidylserine at the outer membrane leaflet of erythrocytes and shedding of microvesicles (MVs) during packed red blood cell storage are alterations assumed to increase the risk of prothrombotic events in recipients. Here, we used rotational thromboelastometry to study the coagulation process in blood samples with erythrocytes from stored PRBCs reconstituted with freshly prepared platelet-rich plasma. We explored the influence of following effects on the coagulation process: 1) PRBC storage duration, 2) differences between erythrocytes from stored PRBCs compared to freshly drawn erythrocytes, and 3) the contribution of added MVs. Interestingly, despite of a higher fraction of PS-positive cells, erythrocytes from PRBCs stored for 6 weeks revealed longer clotting times than samples with erythrocytes stored for 2 or 4 weeks. Further, clotting times and clot formation times were considerably increased in samples reconstituted with erythrocytes from stored PRBCs as compared to fresh erythrocytes. Moreover, MVs added to reconstituted samples elicited only comparably small and ambiguous effects on coagulation. Thus, this study provides no evidence for an amplified clotting process from prolonged storage of PRBCs but on the contrary implicates a loss of function, which may be of clinical significance in massive transfusion. Our observations add to the increasing body of evidence viewing erythrocytes as active players in the clotting process.

What is the Economic Cost of Providing an All Wales Postpartum Haemorrhage Quality Improvement Initiative (OBS Cymru)? A Cost-Consequences Comparison with Standard Care

BACKGROUND AND OBJECTIVE

A postpartum haemorrhage quality improvement initiative (the Obstetric Bleeding Strategy for Wales [OBS Cymru]), including about 60,000 maternities, was adopted across Wales (2017-2018). We performed a cost-consequences analysis to inform ongoing provision and wider uptake.

METHODS

Analysis was based on primary data from the All Wales postpartum haemorrhage database, with a UK National Health Services perspective, a time horizon from delivery until hospital discharge and no discounting. Costs were based on UK published sources with viscoelastic haemostatic assay costs provided by the OBS Cymru national team. Mean costs per eligible patient (postpartum haemorrhage > 1000 mL) were calculated for OBS Cymru, using the early implementation period as a comparator. Modelling allowed comparisons of three scenarios (two predefined and one post hoc) and implementation in different sizes of maternity unit.

RESULTS

All analyses demonstrated consistent savings in blood products, critical care and haematology time, and also a reduced occurrence of massive postpartum haemorrhage (> 2500 mL). Incremental postnatal length of stay varied between scenarios, substantially impacting on total costs. Mean incremental cost of OBS Cymru, compared with standard care, across Wales was £18.41 per patient (postpartum haemorrhage > 1000 mL) or - £10.66 if the length of stay was excluded. Modelling a maternity unit of 5000 births per annum, OBS Cymru incurred an incremental cost of £9.53 per patient with postpartum haemorrhage > 1000 mL.

CONCLUSIONS

OBS Cymru reduces the occurrence of massive postpartum haemorrhage, need for transfusions, quantity of blood products and intensive care. In medium-to-large maternity units (>3000 maternities per annum), the OBS Cymru intervention approaches cost neutrality compared to standard care.

Coagulopathy management of multiple injured patients - a comprehensive literature review of the European guideline 2019

The European guideline on the management of trauma-induced major bleeding and coagulopathy summarises the most relevant recommendations for trauma coagulopathy management. The management of trauma-induced major bleeding should interdisciplinary follow algorithms which distinguish between life-threatening and non-life-threatening bleeding. Point-of-care viscoelastic methods (VEM) assist target-controlled haemostatic treatment. Neither conventional coagulation assays nor VEM should delay treatment in life-threatening trauma-induced bleeding. Adjustments may be rational due to local circumstances, including the availability of blood products, pharmaceuticals, and employees.

Intraoperative transfusion management, antifibrinolytic therapy, coagulation monitoring and the impact on short-term outcomes after liver transplantation-A systematic review of the literature and expert panel recommendations

BACKGROUND

Liver transplantation (LT) is frequently complicated by coagulopathy associated with end-stage liver disease (ESLD), that is, often multifactorial.

OBJECTIVES

The objective of this systematic review was to identify evidence based intraoperative transfusion and coagulation management strategies that improve immediate and short-term outcomes after LT.

METHODS

PRISMA-guidelines and GRADE-approach were followed. Three subquestions were formulated. (Q); Q1: transfusion management; Q2: antifibrinolytic therapy; and Q3: coagulation monitoring.

RESULTS

Sixteen studies were included for Q1, six for Q2, and 10 for Q3. Q1: PRBC and platelet transfusions were associated with higher mortality. The use of prothrombin complex concentrate (PCC) and fibrinogen concentrate (FC) were not associated with reductions in intraoperative transfusion or increased thrombotic events. The use of cell salvage was not associated with hepatocellular carcinoma (HCC) recurrence or mortality. Cell salvage and transfusion education significantly decreased blood product transfusions. Q2: Epsilon-aminocaproic acid (EACA) and tranexamic acid (TXA) were not associated with decreased blood product transfusion, improvements in patient or graft survival, or increases in thrombotic events. Q3: Viscoelastic testing (VET) was associated with decreased allogeneic blood product transfusion compared to conventional coagulation tests (CCT) and is likely to be cost-effective. Coagulation management guided by VET may be associated with increases in FC and PCC use.

CONCLUSION

Q1: A specific blood product transfusion practice is not recommended (QOE; low | Recommendation; weak). Cell salvage and educational interventions are recommended (QOE: low | Grade of Recommendation: moderate). Q2: The routine use of antifibrinolytics is not recommended (QOE; low | Recommendation; weak). Q3: The use of VET is recommended (QOE; low-moderate | Recommendation; strong).

Point-of-care platelet function testing for guided transfusion in neurosurgical management of intracranial hemorrhage: a systematic review

Given the rising prevalence of antiplatelet therapy, rapid preoperative identification of patients with bleeding diathesis is necessary for the guidance of blood product administration. This is especially relevant in neurosurgery for intracranial hemorrhage (ICH), where indiscriminate transfusions may lead to further hemorrhagic or thromboembolic injury. Point-of-care (POC) testing of platelet function is a promising solution to this dilemma, as it has been proven effective in cardiac surgery. However, to date, POC platelet function testing in neurosurgery has not been extensively evaluated. This systematic review appraises the use of POC platelet function test (PFT) in emergency neurosurgery in terms of its impact on patient outcomes.

A comprehensive search was conducted on four electronic databases (Pubmed, MEDLINE, Embase, and Cochrane) for relevant English language articles from their respective inceptions until 1 June 2022. We included all randomized controlled trials and cohort studies that met the following inclusion criteria: (i) involved adult patients undergoing neurosurgery for ICH; (ii) evaluated platelet function via POC PFT; (iii) reported a change in perioperative blood loss; and/or (iv) reported data on treatment-related adverse events and mortality. Assessment of study quality was conducted using the Newcastle Ottawa Quality Assessment Scale for Cohort Studies and Case–Control Studies, and the JBI Critical Appraisal Checklist for Case Series.

The search yielded 2,835 studies, of which seven observational studies comprising 849 patients met the inclusion criteria for this review. Overall, there is evidence that the use of POC PFT to assess bleeding risk reduced bleeding events, thromboembolic adverse outcomes, and the length of hospitalization. However, there is currently insufficient evidence to suggest that using POC PFT improves blood product use, functional outcomes or mortality.

Comparison of the predictive value of thromboelastography and Sonoclot analysis for postoperative bleeding in children undergoing corrective surgery for cyanotic congenital heart disease

Background

The aim of the study was to compare the predictive value of Sonoclot analysis and thromboelastography (TEG) for postoperative bleeding in children younger than 12 years coming for cardiac surgery for congenital cyanotic heart disease.

Methods

This is a prospective, observational study carried out in a single tertiary care military hospital. Ninety patients of the paediatric age group undergoing bypass cardiac surgery for correction of congenital cyanotic heart defect were included in the study. Laboratory-derived values to assess coagulation status (prothrombin time, international normalisation ratio, activated partial thromboplastin time) and point-of-care Sonoclot- and TEG-derived parameters were noted at the start of surgery and postoperatively in all patients. Bleeders were predefined on the basis of chest tube drainage.

Results

The incidence of bleeders was 42.2% (38/90 patients), whereas 57.8% (52/90 patients) were non-bleeders. The postoperative R value and preoperative gbPF test were predictive for postoperative bleeders on multivariate analysis. Postoperative gbPF had the highest area under the curve (0.72), with a cut-off value of 1.75, and gbPF had 82% sensitivity and 71% specificity in predicting significant postoperative bleeding in paediatric cyanotic congenital heart surgeries. Transfusion requirements and mechanical ventilation duration were higher in bleeders; however; length of intensive care unit stay, incidence of sepsis and mortality were similar in both the groups.

Conclusion

Bleeding in patients undergoing corrective surgery for cyanotic congenital heart disease could be predicted by the preoperative gbPF and postoperative R value. Among these, preoperative gbPF has the maximum predictive value.

Coagulopathy and hemostasis management in patients undergoing liver transplantation: Defining a dynamic spectrum across phases of care

Patients with acute and chronic liver disease present with a wide range of disease states and severity that may require liver transplantation (LT). Physiologic alterations occur that are dynamic throughout all phases of perioperative care, creating complex management scenarios that necessitate multidisciplinary clinical care. Specifically, alterations in hemostasis in liver disease can be pronounced and evolve with disease progression over time. Recent studies and society guidance address this emerging paradigm and offer recommendations to assist with hemostatic management in patients with liver disease. However, patients undergoing LT are unique and diverse, often with unstable disease that requires specialized approaches. Our aim is to provide a focused review of hemostatic management of the LT patient, distinguish unique aspects of the three main phases of care (before LT, perioperative, and after LT), and identify knowledge gaps and critical areas of future research.

Utility of viscoelastic hemostatic assay to guide hemostatic resuscitation in trauma patients: a systematic review

Objective

Viscoelastic hemostatic assay (VHA) provides a graphical representation of a clot’s lifespan and reflects the real time of coagulation. It has been used to guide trauma resuscitation; however, evidence of the effectiveness of VHAs is still limited. This systematic review aims to summarize the published evidence to evaluate the VHA-guided strategy in resuscitating trauma patients.

Methods

The PubMed, Embase, and Web of Science databases were searched from their inception to December 13, 2021. Randomized controlled trials (RCTs) or observational studies comparing VHA-guided transfusion to controls in resuscitating trauma patients were included in this systematic review.

Results

Of the 7743 records screened, ten studies, including two RCTs and eight observational studies, met the inclusion criteria. There was great heterogeneity concerning study design, enrollment criterion, VHA device, VHA-guided strategy, and control strategy. Thrombelastography (TEG) was used as a guiding tool for transfusion in eight studies, and rotational thromboelastometry (ROTEM), and TEG or ROTEM were used in the other two studies. The overall risk of bias assessment was severe or mild in RCTs and was severe or moderate in observational studies. The main outcomes reported from the included studies were blood transfusion (n = 10), mortality (n = 10), hospital length of stay (LOS) (n = 7), intensive care unit LOS (n = 7), and cost (n = 4). The effect of the VHA-guided strategy was not always superior to the control. Most of the studies did not find significant differences in the transfusion amount of red blood cells (n = 7), plasma (n = 5), platelet (n = 7), cryoprecipitate/fibrinogen (n = 7), and mortality (n = 8) between the VHA-guided group and control group. Notable, two RCTs showed that the VHA-guided strategy was superior or equal to the conventional coagulation test-guided strategy in reducing mortality, respectively.

Conclusion

Although some studies demonstrated VHA-guided strategy probable benefit in reducing the need for blood transfusion and mortality when resuscitating trauma patients, the evidence is still not robust. The quality of evidence was primarily downgraded by the limited number of included studies and great heterogeneity and severe risk of bias in these. Further studies are strongly recommended.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13017-022-00454-8.

Prophylactic administration of tranexamic acid combined with thromboelastography-guided hemostatic algorithm reduces allogeneic transfusion requirements during pediatric resective epilepsy surgery: A randomized controlled trial

Background: Intraoperative bleeding and allogeneic transfusion remain common problems in pediatric resective epilepsy surgery. Tranexamic acid (TXA) is a widely recommended antifibrinolytic drug that reduces blood loss and transfusion requirements for bleeding patients. Thromboelastography (TEG)-guided hemostatic algorithm is commonly used in bleeding management. This trial was designed to validate the efficacy of a multimodal coagulation therapy involving continuous TXA infusion with TEG-guided hemostatic algorithm in reducing allogeneic exposure risk in pediatric resective epilepsy surgery.

Methods: Eighty-three children undergoing resective epilepsy surgery were randomized into a treatment group (Group T; n = 42) and a control group (Group C; n = 41). Group T received prophylactic TXA (10 mg/kg followed by 5 mg/kg/h) with TEG-guided hemostatic algorithm, whereas Group C received conventional coagulation management. The primary outcome was allogeneic transfusion rate during surgery, and the secondary outcomes were intraoperative blood loss, incidence of postoperative seizures, and thromboembolic events during hospitalization.

Results: The incidence of intraoperative allogeneic transfusion reduced by 34.7% with the use of a multimodal coagulation therapy (19.0% in Group T vs. 53.7% in Group C; RR 0.355, 95% CI 0.179–0.704; p = 0.001). This was mainly triggered by a significant reduction (44.1%) in intraoperative plasma transfusion (7.1% in Group T vs. 51.2% in Group C; RR 0.139, 95% CI 0.045–0.432; p = 0.000). The risk of intraoperative RBC transfusion was lower in Group T than in Group C, but the difference was not statistically significant (14.3% in Group T vs. 29.3% in Group C; RR 0.488, 95% CI 0.202–1.177; p = 0.098). No platelets were transfused in both groups. Further, 19 (45.2%) patients in Group T received fibrinogen concentrates guided by TEG data, whereas 1 (2.4%) patient in Group C received fibrinogen concentrates empirically. There were no significant differences in estimated blood loss and postoperative seizures between the two groups, and no thromboembolic events were observed after surgery.

Conclusion: Prophylactic administration of TXA combined with TEG-guided hemostatic algorithm can be an effective multimodal coagulation strategy for reducing allogeneic transfusion requirements during pediatric resective epilepsy surgery.

Clinical Trial Registration:www.chictr.org.cn/index.aspx, identifier ChiCTR1800016188.

Impact of Anticoagulation/Antiplatelet Therapy on Femoropopliteal Bypass Graft Outcomes

INTRODUCTION

Anticoagulant and antiplatelet (AC/AP) medications have been reported to improve bypass graft patency, however, the optimal AC/AP strategy remains unclear in the heterogenous peripheral artery disease population.

METHODS

A multi-institutional retrospective review utilizing the Research Patient Data Registry (RPDR) database from 1995-2020 was performed for all patients who underwent femoropopliteal bypass procedures. Electronic medical records were used to obtain demographic information, comorbidities, smoking status, operative details (bypass target), postoperative AC/AP medications, postoperative complications, and long-term outcomes were reviewed for the cohort. Cox proportional hazards model was used to determine independent risk factors for major adverse limb events (MALE) following bypass. MALE was defined as reintervention for patency or major amputation of index limb (above- or below-knee amputation).

RESULTS

A total of 1421 patients underwent femoropopliteal bypass between 1995-2020 throughout five institutions included in this study. Complete data was available for 1292/1421 (90.9%) patients. Indications for bypass included intermittent claudication (21.4%), rest pain (30.3%), tissue loss (33.5%), and non-atherosclerotic disease (14.8%). Distal bypass targets comprised above-knee (38.6%) and below-knee (61.4%) popliteal arteries. Patients were divided into six groups based on postoperative AC/AP use including none (n=57, 4.4%), mono-antiplatelet therapy (MAPT) (n=587, 45.4%), dual antiplatelet therapy (DAPT) (n=214, 16.6%), AC alone (n=73, 5.7%), AC+MAPT (n=319, 24.7%), and AC+DAPT (n=42, 3.3%). Postoperative bleeding complications were low for both hematoma (3.7%) and pseudoaneurysm (0.7%). There was no difference in bleeding complications across AC/AP groups (hematoma p=0.61, pseudoaneurysm p=0.31). After adjusting for patient factors, below-knee bypass target (HR 1.25 [1.04-1.52], p=0.019) and bypass for tissue loss (HR 1.40 [1.04-1.88], p=0.028) were independent predictors for MALE. Great saphenous vein conduit trended towards protection for MALE, compared with prosthetic grafts (HR 0.84 [0.70-1.01], p=0.06). No AC/AP regimen was associated with of MALE, even stratifying by above-knee and below-knee bypass cohorts. Median follow-up period was two years.

CONCLUSIONS

Among patients undergoing femoropopliteal bypass grafting, no combination of anticoagulation or antiplatelet medications was associated with improved graft patency, however, a below-knee target and tissue loss were associated with adverse limb events. Anticoagulation and antiplatelet regimen may be individualized post-bypass with regard to other concomitant medical comorbidities.

Faster Time to Treatment Decision of Viscoelastic Coagulation Test Results through Improved Perception with the Animated Visual Clot: A Multicenter Comparative Eye-Tracking Study

As the interpretation of viscoelastic coagulation test results remains challenging, we created Visual Clot, an animated blood clot aiming to facilitate raw rotational thromboelastometry (ROTEM) parameters. This study investigated anesthesia personnel’s cognitive processing in managing simulated bleeding scenarios using eye-tracking technology. This multicenter, international, computer-based study across five large, central European hospitals included 35 participants with minimal to no prior experience interpreting viscoelastic test results. Using eye-tracking technology and an iPad tagged with quick response codes, we defined the time to treatment decision and the time on screen surface in seconds of correctly solved scenarios as our outcomes. The median time to treatment decision was 52 s for Visual Clot and 205 s for ROTEM (p < 0.0001). The probability of solving the scenario correctly was more than 8 times higher when using Visual Clot than when using ROTEM (Hazard ratio [HR] 8.54, 95% CI from 6.5 to 11.21; p < 0.0001). Out of 194 correctly answered scenarios of participants with the eye-tracker, 154 (79.4%) were solved with Visual Clot and 40 (20.6%) with ROTEM. Participants spent on average 30 s less looking at the screen surface with Visual Clot compared to ROTEM (Coefficient −30.74 s, 95% CI from −39.27 to −22.27; p < 0.0001). For a comparison of the two modalities in terms of information transfer, we calculated the percentage of time on the screen surface of the overall time to treatment decision, which with Visual Clot was 14 percentage points shorter than with ROTEM (Coefficient −14.55, 95% CI from −20.05 to −9.12; p < 0.0001). Visual Clot seems to improve perception and detection of coagulopathies and leads to earlier initiation of the appropriate treatment. In a high-pressure working environment such as the operating and the resuscitation room, correct and timely decisions regarding bleeding management may have a relevant impact on patients’ outcomes.

Comparison of coagulation monitoring using ROTEM and Sonoclot devices in cardiac surgery. A single-centre prospective observational study

BACKGROUND

Viscoelastic tests (VETs) are recommended during cardiac surgery to monitor coagulation status and guide transfusion. We compared the results of two VETs, the Sonoclot Analyzer and the ROTEM Sigma. Agreement between viscoelastic tests' subdiagnoses and overall diagnosis severity was assessed. Correlations with conventional coagulation tests (CCT) and the discriminatory potential of numerical VET outputs for transfusion thresholds was determined.

METHODS

Single-centre, prospective observational study in a tertiary academic centre. In fifty adult patients undergoing elective cardiac surgery, parallel Sonoclot, ROTEM and CCT analysis was performed before heparin, or after protamine or coagulation product administration. All patients completed the study, resulting in 139 data points.

RESULTS

Agreement on the severity of coagulation disorders was acceptable (83%), but poor (27%) on the differentiation of the underlying causes. Correlations between ROTEM parameters and CCT were good (post-protamine: FIBTEM A5 (r2 = 0.90 vs fibrinogen) and EXTEM-FIBTEM A5 difference (r2 = 0.81 vs platelet count) ). Sonoclot correlated less (Clot Rate (r2 = 0.25 vs fibrinogen) and Platelet Function (r2 = 0.43 vs platelet count)). This was reflected in the discriminatory potential of these parameters as found by linear mixed modelling. We suggest clinically useful grey zones for VET cutoff interpretation.

CONCLUSIONS

ROTEM and Sonoclot accord well on the detection of severity of coagulation dysfunction, but not on the diagnosis of the underlying cause. ROTEM correlated more closely with CCT then Sonoclot. We propose a testing strategy that could lead to a cost-effective approach to the bleeding cardiac surgery patient.

Sonoclot’s usefulness in prediction of cardiopulmonary arrest prognosis: A proof of concept study

The aim of the present study was to evaluate the usefulness of measuring whole blood coagulation with Sonoclot to predict return of spontaneous circulation (ROSC) in patients with out-of-hospital cardiopulmonary arrest (OHCA). This was a prospective, observational clinical study on patients with OHCA who were transferred to our emergency department between August 2016 and July 2018. Patients were divided into two groups: patients with return of spontaneous circulation (ROSC[+] group) and those without (ROSC[−] group). We compared the activated clotting time (ACT), clot rate (CR), and platelet function (PF) as measured with Sonoclot, and the fibrinogen degradation products (FDP) level and D-dimer level between the two groups. We analyzed 87 patients: 37 in the ROSC(+) and 50 in the ROSC(−) groups. Regarding ACT, CR, PF, FDP, and D-dimer, we used receiver operating characteristic (ROC) curves to examine how well each factor predicts ROSC. The area under the ROC curve (AUC) of CR was higher than that of the FDP and D-dimer levels. Among patients with cardiogenic cardiac arrest, the AUC of CR was higher than the AUCs of other coagulation factors. In conclusion, viscoelastic blood coagulation measurements using Sonoclot may be useful for predicting ROSC in OHCA patients.

Viscoelastic Hemostatic Assays: A Primer on Legacy and New Generation Devices

Viscoelastic hemostatic assay (VHAs) are whole blood point-of-care tests that have become an essential method for assaying hemostatic competence in liver transplantation, cardiac surgery, and most recently, trauma surgery involving hemorrhagic shock. It has taken more than three-quarters of a century of research and clinical application for this technology to become mainstream in these three clinical areas. Within the last decade, the cup and pin legacy devices, such as thromboelastography (TEG^® 5000) and rotational thromboelastometry (ROTEM^® delta), have been supplanted not only by cartridge systems (TEG^® 6S and ROTEM^® sigma), but also by more portable point-of-care bedside testing iterations of these legacy devices (e.g., Sonoclot^®, Quantra^®, and ClotPro^®). Here, the legacy and new generation VHAs are compared on the basis of their unique hemostatic parameters that define contributions of coagulation factors, fibrinogen/fibrin, platelets, and clot lysis as related to the lifespan of a clot. In conclusion, we offer a brief discussion on the meteoric adoption of VHAs across the medical and surgical specialties to address COVID-19-associated coagulopathy.

Case Report: Rotational Thromboelastometry in Taipan Envenomation

Venom-induced consumption coagulopathy (VICC) is one of the most dangerous syndromes caused by snake envenomation and can be caused by several snake species worldwide, including the Australian coastal taipan. Rotational thromboelastometry (ROTEM) provides real-time point-of-care information on all stages of clot formation; however, it has yet to be formally evaluated in the assessment of VICC. We report three cases of Taipan envenomation causing VICC and the associated ROTEM results. The implications for future use of ROTEM in the assessment, management, and further research of VICC are discussed.

Cryoprecipitate as an alternative to platelet transfusion in thrombocytopenia

Platelet transfusions are not always available for bleeding in severe thrombocytopenia, as storage outside of major centers is limited by their short shelf-life. Data are lacking to support alternative available blood products; however, additional fibrinogen has been shown to enhance clot formation in vitro. To test the hypothesis that cryoprecipitate supplementation could improve clot formation in severe thrombocytopenia, eight hematological malignancy patients with platelet counts under 10 × 109/L each had 10 units of apheresis cryoprecipitate transfused prior to planned prophylactic platelet transfusions. The primary endpoint of thromboelastometry amplitude at 20 min increased by a mean of 5.1 mm (p < 0.01) following cryoprecipitate transfusion despite persisting thrombocytopenia. Thromboelastometry clotting times reduced by a mean of 7.8 s (p < 0.05) and alpha angle increased by a mean of 10.6⁰ (p < 0.01). These results are consistent with cryoprecipitate enhancing the strength of the fibrin/platelet meshwork within the forming thrombus. While platelet transfusion remains the standard of care, where platelet supplies are limited, these data provide a rationale for the use of cryoprecipitate to obtain hemostasis in bleeding thrombocytopenic patients.

Pro-Con Debate: Viscoelastic Hemostatic Assays Should Replace Fixed Ratio Massive Transfusion Protocols in Trauma

Major trauma patients at risk of traumatic coagulopathy are commonly treated with early clotting factor replacement to maintain hemostasis and prevent microvascular bleeding. In the United States, trauma transfusions are often dosed by empiric, low-ratio massive transfusion protocols, which pair plasma and platelets in some ratio relative to the red cells, such as the "1:1:1" combination of 1 units of red cells, 1 unit of plasma, and 1 donor's worth of pooled platelets. Empiric transfusion increases the rate of overtransfusion when unnecessary blood products are administered based on a formula and not on at patient's hemostatic profile. Viscoelastic hemostatic assays (VHAs) are point-of-care hemostatic assays that provided detailed information about abnormal clotting pathways. VHAs are used at many centers to better target hemostatic therapies in trauma. This Pro/Con section will address whether VHA guidance should replace empiric fixed ratio protocols in major trauma.

Clinical application of viscoelastic point-of-care tests of coagulation-shifting paradigms

Bleeding during cardiac surgery, liver transplant, trauma and post partum hemorrhage are often multifactorial and these factors are dynamic as new factors crop up during the course of management. Conventional tests of coagulation offer information of a part of the coagulation system and also is time consuming. Viscoelastic point of care tests (VE POCTs) like rotational thromboelastometry, thromboelastogram and Sonoclot, are based on analysis of the viscoelastic properties of clotting blood and provide information for the entire coagulation pathway. In this comprehensive review being presented here, we have examined the pros and cons of VE POCTs including clinical, cost and survival benefits. The recommendations of the various guidelines regarding use of VE POCTs in various scenarios have been discussed. The review also tried to offer suggestions as to their optimal role in management of bleeding during cardiac surgeries, extracorporeal membrane oxygenation, left ventricular assist devices, liver transplant and briefly in trauma and postpartum hemorrhage.

The Role of TEG and ROTEM in Damage Control Resuscitation

ABSTRACT

Trauma-induced coagulopathy is associated with very high mortality, and hemorrhage remains the leading preventable cause of death after injury. Directed methods to combat coagulopathy and attain hemostasis are needed. The available literature regarding viscoelastic testing, including thrombelastography (TEG) and rotational thromboelastometry (ROTEM), was reviewed to provide clinically relevant guidance for emergency resuscitation. These tests predict massive transfusion and developing coagulopathy earlier than conventional coagulation testing, within 15 min using rapid testing. They can guide resuscitation after trauma, as well. TEG and ROTEM direct early transfusion of fresh frozen plasma when clinical gestalt has not activated a massive transfusion protocol. Reaction time and clotting time via these tests can also detect clinically significant levels of direct oral anticoagulants. Slowed clot kinetics suggest the need for transfusion of fibrinogen via concentrates or cryoprecipitate. Lowered clot strength can be corrected with platelets and fibrinogen. Finally, viscoelastic tests identify fibrinolysis, a finding associated with significantly increased mortality yet one that no conventional coagulation test can reliably detect. Using these parameters, guided resuscitation begins within minutes of a patient's arrival. A growing body of evidence suggests this approach may improve survival while reducing volumes of blood products transfused.

Diagnostic Modalities in Critical Care: Point-of-Care Approach

The concept of intensive care units (ICU) has existed for almost 70 years, with outstanding development progress in the last decades. Multidisciplinary care of critically ill patients has become an integral part of every modern health care system, ensuing improved care and reduced mortality. Early recognition of severe medical and surgical illnesses, advanced prehospital care and organized immediate care in trauma centres led to a rise of ICU patients. Due to the underlying disease and its need for complex mechanical support for monitoring and treatment, it is often necessary to facilitate bed-side diagnostics. Immediate diagnostics are essential for a successful treatment of life threatening conditions, early recognition of complications and good quality of care. Management of ICU patients is incomprehensible without continuous and sophisticated monitoring, bedside ultrasonography, diverse radiologic diagnostics, blood gas analysis, coagulation and blood management, laboratory and other point-of-care (POC) diagnostic modalities. Moreover, in the time of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, particular attention is given to the POC diagnostic techniques due to additional concerns related to the risk of infection transmission, patient and healthcare workers safety and potential adverse events due to patient relocation. This review summarizes the most actual information on possible diagnostic modalities in critical care, with a special focus on the importance of point-of-care approach in the laboratory monitoring and imaging procedures.

A Systematic Review of Thromboelastography Utilization in Vascular and Endovascular Surgery

OBJECTIVE

Thromboelastography (TEG) is diagnostic modality that analyzes real-time blood coagulation parameters. Clinically, TEG primarily allows for directed blood component resuscitation among patients with acute blood loss and coagulopathy. The utilization of TEG has been widely adopted in among other surgical specialties; however, its use in vascular surgery is less prominent. We aimed to provide an up-to-date review of TEG utilization in vascular and endovascular surgery.

METHODS

Using PRISMA guidelines, a literature review with the Medical Subject Headings (MeSH) terms "TEG and arterial events", "TEG and vascular surgery", "TEG and vascular", "TEG and endovascular surgery", "TEG and endovascular", "TEG and peripheral artery disease", "TEG and prediction of arterial events", "TEG and prediction of complications ", "TEG and prediction of thrombosis", "TEG and prediction of amputation", and "TEG and amputation" was performed in Cochrane and PubMed databases to identify all peer-reviewed studies of TEG utilization in vascular surgery, written between 2000-2021 in the English language. The free text and MeSH subheadings search terms included diagnosis, complications, physiopathology, surgery, mortality, and therapy to further restrict the articles. Studies were excluded if they were not in humans or pertaining to vascular or endovascular surgery. Additionally, case reports and studies with limited information regarding TEG utilization were excluded. Each study was independently reviewed by two researchers to assess for eligibility.

RESULTS

Of the 262 studies identified through the MeSH strategy, 15 studies met inclusion criteria and were reviewed and summarized. Literature on TEG utilization in vascular surgery spanned cerebrovascular disease (n=3), peripheral arterial disease (n=3), arteriovenous malformations (n=1), venous thromboembolic events (n=7), and perioperative bleeding and transfusion (n=1). In cerebrovascular disease, TEG may predict the presence and stability of carotid plaques, analyze platelet function before carotid stenting, and compare efficacy of antiplatelet therapy after stent deployment. In peripheral arterial disease, TEG has been used to predict disease severity and analyze the impact of contrast on coagulation parameters. In venous disease, TEG may predict hypercoagulability and thromboembolic events among various patient populations. Finally, TEG can be utilized in the postoperative setting to predict hemorrhage and transfusion requirements.

CONCLUSIONS

This systematic review provides an up-to-date summarization of TEG utilization in multiple facets of vascular and endovascular surgery.

Avatrombopag and lusutrombopag for thrombocytopenia in people with chronic liver disease needing an elective procedure: a systematic review and cost-effectiveness analysis

BACKGROUND

There have been no licensed treatment options in the UK for treating thrombocytopenia in people with chronic liver disease requiring surgery. Established management largely involves platelet transfusion prior to the procedure or as rescue therapy for bleeding due to the procedure.

OBJECTIVES

To assess the clinical effectiveness and cost-effectiveness of two thrombopoietin receptor agonists, avatrombopag (Doptelet^®; Dova Pharmaceuticals, Durham, NC, USA) and lusutrombopag (Mulpleta^®; Shionogi Inc., London, UK), in addition to established clinical management compared with established clinical management (no thrombopoietin receptor agonist) in the licensed populations.

DESIGN

Systematic review and cost-effectiveness analysis.

SETTING

Secondary care.

PARTICIPANTS

Severe thrombocytopenia (platelet count of < 50,000/µl) in people with chronic liver disease requiring surgery.

INTERVENTIONS

Lusutrombopag 3 mg and avatrombopag (60 mg if the baseline platelet count is < 40,000/µl and 40 mg if it is 40,000-< 50,000/µl).

MAIN OUTCOME MEASURES

Risk of platelet transfusion and rescue therapy or risk of rescue therapy only.

REVIEW METHODS

Systematic review including meta-analysis. English-language and non-English-language articles were obtained from several databases including MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials, all searched from inception to 29 May 2019.

ECONOMIC EVALUATION

Model-based cost-effectiveness analysis.

RESULTS

From a comprehensive search retrieving 11,305 records, six studies were included. Analysis showed that avatrombopag and lusutrombopag were superior to no thrombopoietin receptor agonist in avoiding both platelet transfusion and rescue therapy or rescue therapy only, and mostly with a statistically significant difference (i.e. 95% confidence intervals not overlapping the point of no difference). However, only avatrombopag seemed to be superior to no thrombopoietin receptor agonist in reducing the risk of rescue therapy, although far fewer patients in the lusutrombopag trials than in the avatrombopag trials received rescue therapy. When assessing the cost-effectiveness of lusutrombopag and avatrombopag, it was found that, despite the success of these in avoiding platelet transfusions prior to surgery, the additional long-term gain in quality-adjusted life-years was very small. No thrombopoietin receptor agonist was clearly cheaper than both lusutrombopag and avatrombopag, as the cost savings from avoiding platelet transfusions were more than offset by the drug cost. The probabilistic sensitivity analysis showed that, for all thresholds below £100,000, no thrombopoietin receptor agonist had 100% probability of being cost-effective.

LIMITATIONS

Some of the rescue therapy data for lusutrombopag were not available. There were inconsistencies in the avatrombopag data. From the cost-effectiveness point of view, there were several additional important gaps in the evidence required, including the lack of a price for avatrombopag.

CONCLUSIONS

Avatrombopag and lusutrombopag were superior to no thrombopoietin receptor agonist in avoiding both platelet transfusion and rescue therapy, but they were not cost-effective given the lack of benefit and increase in cost.

FUTURE WORK

A head-to-head trial is warranted.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42019125311.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 51. See the NIHR Journals Library website for further project information.

Viscoelastic monitoring in trauma resuscitation

BACKGROUND

Traumatic injury results in both physical and physiologic insult. Successful care of the trauma patient depends upon timely correction of both physical and biochemical injury. Trauma-induced coagulopathy is a derangement of hemostasis and thrombosis that develops rapidly and can be fatal if not corrected. Viscoelastic monitoring (VEM) assays have been developed to provide rapid, accurate, and relatively comprehensive depictions of an individual's coagulation profile. VEM are increasingly being integrated into trauma resuscitation guidelines to provide dynamic and individualized guidance to correct coagulopathy.

STUDY DESIGN AND METHODS

We performed a narrative review of the search terms viscoelastic, thromboelastography, thromboelastometry, TEG, ROTEM, trauma, injury, resuscitation, and coagulopathy using PubMed. Particular focus was directed to articles describing algorithms for management of traumatic coagulopathy based on VEM assay parameters.

RESULTS

Our search identified 16 papers with VEM-guided resuscitation strategies in adult patients based on TEG, 12 such protocols in adults based on ROTEM, 1 protocol for children based on TEG, and 2 protocols for children based on ROTEM.

CONCLUSIONS

This review presents evidence to support VEM use to detect traumatic coagulopathy, discusses the role of VEM in trauma resuscitation, provides a summary of proposed treatment algorithms, and discusses pending questions in the field.

Simplified treatment algorithm for the management of trauma-induced hemorrhage without viscoelastic testing

Uncontrolled bleeding after major trauma remains a significant cause of death, with up to a third of trauma patients presenting with signs of coagulopathy at hospital admission. Rapid correction of coagulopathy is therefore vital to improve mortality rates and patient outcomes in this population. Early and repeated monitoring of coagulation parameters followed by clear protocols to correct hemostasis is the recommended standard of care for bleeding trauma patients. However, although a number of treatment algorithms are available, these are frequently complex and can rely on the use of viscoelastic testing, which is not available in all treatment centers. We therefore set out to develop a concise and pragmatic algorithm to guide treatment of bleeding trauma patients without the use of point-of-care viscoelastic testing. The algorithm we present here is based on published guidelines and research, includes recommendations regarding treatment and dosing, and is simple and clear enough for even an inexperienced physician to follow. In this way, we have demonstrated that treatment protocols can be developed and adapted to the resources available, to offer clear and relevant guidance to the entire trauma team.

Health Economic Evidence of Point-of-Care Testing: A Systematic Review

OBJECTIVE

Point-of-care testing (POCT) has become an essential diagnostic technology for optimal patient care. Its implementation, however, still falls behind. This paper reviews the available evidence on the health economic impact of introducing POCT to assess if poor POCT uptake may be related to lacking evidence.

STUDY DESIGN

The Scopus and PubMed databases were searched to identify publications describing a health economic evaluation of a point-of-care (POC) test. Data were extracted from the included publications, including general and methodological characteristics as well as the study results summarized in either cost, effects or an incremental cost-effectiveness ratio. Results were sorted into six groups according to the POC test's purpose (diagnosis, screening or monitoring) and care setting (primary care or secondary care). The reporting quality of the publications was determined using the CHEERS checklist.

RESULTS

The initial search resulted in 396 publications, of which 44 met the inclusion criteria. Most of the evaluations were performed in a primary care setting (n = 31; 70.5%) compared with a secondary care setting (n = 13; 29.5%). About two thirds of the evaluations were on POC tests implemented with a diagnostic purpose (n = 28; 63.6%). More than 75% of evaluations concluded that POCT is recommended for implementation, although in some cases only under specific circumstances and conditions. Compliance with the CHEERS checklist items ranged from 20.8% to 100%, with an average reporting quality of 72.0%.

CONCLUSION

There were very few evaluations in this review that advised against the implementation of POCT. However, the uptake of POCT in many countries remains low. Even though the evaluations included in this review did not always include the full long-term benefits of POCT, it is clear that health economic evidence across a few dimensions of value already indicate the benefits of POCT. This suggests that the lack of evidence on POCT is not the primary barrier to its implementation and that the low uptake of these tests in clinical practice is due to (a combination of) other barriers. In this context, aspects around organization of care, support of clinicians and quality management may be crucial in the widespread implementation of POCT.

Association of Plasma Fibrinogen and Thromboelastography With Blood Loss in Complex Cardiac Surgery

Postoperative coagulopathic bleeding is common in cardiac surgery and is associated with increased morbidity and mortality. Ideally, real-time information on in-vivo coagulation should be available. However, up to now it is unclear which perioperative coagulation parameters can be used best to accurately identify patients at increased risk of bleeding. The present study analyzed the associations of perioperative fibrinogen concentrations and whole blood viscoelastic tests with postoperative bleeding in 89 patients undergoing combined cardiac surgery procedures. Postoperative bleeding was recorded until 24 hours after surgery. Regression analyses were performed to establish associations between blood loss and coagulation parameters after cardiopulmonary bypass including a prediction model with known confounding factors for bleeding. Coagulation tests show large changes over the perioperative course with the strongest coagulopathic deviations from baseline after cardiopulmonary bypass. After adjustment for multiple confounders, viscoelastic clot strength instead of fibrinogen concentration showed a similar performance for 24 hour blood loss and a better performance for 6 hour blood loss. This makes intraoperative viscoelastic testing a useful tool to strengthen early clinical decision-making with the potential to reduce perioperative blood transfusions.

Clinical Validation of Global Coagulation Tests to Guide Blood Component Transfusions in Cirrhosis and ACLF

BACKGROUND AND AIMS

Patients with cirrhosis and acute-on-chronic liver failure (ACLF) may have bleeding complications and need for invasive procedures. Point-of-care (POC) coagulation tests like thromboelastography (TEG) and Sonoclot may be better for guiding patient management than the standard coagulation tests (SCTs), like prothrombin time, platelet count and international normalized ratio.

METHODS

We prospectively compared and validated the POC tests and SCTs in 70 persons with ACLF and 72 persons with decompensated cirrhosis who had clinical bleeding and checked for episodes of re-bleeding and transfusion requirements. We assessed pre-procedure requirement of blood components when correction was done based on an SCT or POC strategy.

RESULTS

Episodes of bleeding were seen in 45% and 28% of ACLF and cirrhosis patient, respectively (p=0.036), with the major site of bleeding being gastrointestinal (31% and 16%, respectively). Platelet counts correlated with TEG-maximum amplitude in cirrhosis (p=0.045) and prothrombin time correlated positively with TEG-reaction (R) time (p=0.032), TEG-Clot kinetics (K) time (p=0.042), Son-activated clotting time (p=0.038) and negatively with clot rate (p=0.043) in ACLF, making these correctable target variables in POC transfusion algorithms. Of 223 procedures, transfusion of fresh frozen plasma and platelet concentrate was reduced by 25% (p=0.035) and 20.8% (p=0.045) by using a POC strategy in 76 patients. Correction of deranged Son-activated clotting time and TEG-reaction time was noted in 68% and 72% after 24 h of fresh frozen plasma transfusion in ACLF and 85% and 80% in cirrhosis, respectively.

CONCLUSIONS

Our study clinically validates that POC tests can better detect coagulation defects and transfusion thresholds in ACLF and cirrhosis, whereas use of conventional tests appear to be less suitable in patients with clinical bleeding.

TRIAL REGISTRATION

NCT04332484.