Viscoelastic testing inside and beyond the operating room

[Design of a dynamic measurement system for Bl factor spatial distribution of resonant blood viscoelastic sensor]

Bl factor is a key system parameter of the resonant blood viscoelastic sensor. In this paper, a dynamic measurement system for the spatial distribution of Bl factor based on velocity amplitude and motional impedance was designed. The system extracted the velocity amplitude and motional impedance of the coil under the dynamic condition of driving the sensor to generate simple harmonic oscillations using laser displacement and impedance analysis combined with in-phase/quadrature demodulation algorithm, and controlled the equilibrium position of the coil by adjusting the direct current component of the excitation current to realize the position scanning. In the position interval of [-240, 240] μm, the maximum coefficient of variation of the measurement results was 0.077 3%, and the maximum relative error to the simulation results was 2.937 9%, with a linear fitting correlation coefficient R 2 = 0.996 8. The system can be used to accurately measure the spatial distribution of Bl factor of the resonant blood viscoelastic sensor, which provides a technical support for the verification of the design of the sensor magnetic circuit.

Preliminary evaluation of reference intervals for a point-of-care viscoelastic coagulation monitor (VCM Vet) in healthy adult horses

OBJECTIVE

To evaluate a point-of-care viscoelastic coagulation monitor (VCM Vet) for use in horses by assessing variability between devices and establish reference intervals (RIs) for healthy adult horses.

DESIGN

Prospective observational study.

SETTING

Two university teaching hospitals.

ANIMALS

Healthy adult horses (n = 68).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Blood collected by direct jugular venipuncture was applied directly from the syringe into 2 VCM Vet cassettes to establish coefficients of variation (CVs) and RIs for reported parameters of clotting time (CT), clot formation time (CFT), alpha angle, amplitude at 10 and 20 minutes, maximum clot firmness, and lysis index at 30 and 45 minutes. CVs for each parameter were within clinical tolerance. There was a significant difference in CT between institutions (P < 0.001). Differences in CV were found between institutions for CT (P = 0.003) and CFT (P = 0.01). Healthy horse RIs were calculated for the overall data set and each individual institution. Calculated RIs were as follows: CT, 255.6-1233.9 seconds; CFT, 89.4-581 seconds; alpha angle, 11.4-53.6°; maximum clot firmness, 18-37.7; lysis index at 30 minutes, 97.3%-102.1%; lysis index at 45 minutes, 80.8%-103.3%; amplitude at 10 minutes, 8.7-28.3; and amplitude at 20 minutes, 17.4-35.7.

CONCLUSIONS

VCM Vet is a repeatable and practical option for rapid point-of-care assessment of hemostasis in horses but has a wide RI and is susceptible to variability. Establishment of institution-specific RIs is recommended.

Coagulopathy and Emergent Reversal of Anticoagulation

More patients than ever are presenting for urgent or emergent procedures while therapeutically anticoagulated for various medical indications. Medications including warfarin, antiplatelet agents such as clopidogrel, direct oral anticoagulants such as apixaban, and even heparin or heparinoids may be present. Each of these medication classes presents its own challenges when coagulopathy needs to be quickly corrected. This review article presents evidence-based discussions of monitoring and reversal of these medication-induced coagulopathies. In addition, there will be a brief discussion of other potential coagulopathies that may be encountered in providing acute care anesthesia.

Investigating the association between IL-6 antagonist therapy and blood coagulation in critically ill patients with COVID-19: a protocol for a prospective, observational, multicentre study

INTRODUCTION

Hypercoagulation is one the main features of COVID-19. It is induced by the hyperinflammatory response that shifts the balance of haemostasis towards pro-coagulation. Interleukin-6 (IL-6) antagonist therapy has been recommended in certain subgroups of critically ill patients with COVID-19 to modulate inflammatory response. The interaction between immune response and haemostasis is well recognised. Therefore, our objective is to evaluate whether the modulation of the inflammatory response by IL-6 antagonist inflicts any changes in whole blood coagulation as assessed by viscoelastic methods in critically ill patients with COVID-19.

METHODS AND ANALYSIS

In this prospective observational study, we are going to collect data on inflammatory parameters and blood coagulation using the ClotPro^® device. The primary outcome is the change of the fibrinolytic system measured by the Lysis Time and Lysis onset time before and after immunomodulation therapy. Data will be collected before the IL-6 antagonist administration at baseline (T₀) then after 24, 48 hours, then on day 5 and 7 (T_1-4, respectively). Secondary outcomes include changes in other parameters related to inflammation, blood coagulation and biomarkers of endothelial injury.

ETHICS AND DISSEMINATION

Ethical approval was given by the Medical Research Council of Hungary (1405-3/2022/EÜG). All participants provided written consent. The results of the study will be disseminated through peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05218369; Clinicaltrials.gov.

Viscoelastic Testing Prior to Non-surgical Procedures Reduces Blood Product Use Without Increasing Bleeding Risk in Cirrhosis

BACKGROUND/AIMS

Thromboelastography (TEG) and Rotational Thromboelastometry (ROTEM) analyze hemostatic function in patients with coagulopathy. We sought to quantify the impact of TEG and ROTEM-guided transfusion algorithms on blood product utilization in patients with cirrhosis undergoing non-surgical procedures.

METHODS

We performed a systematic review and meta-analysis on the utility of viscoelastic testing prior to non-surgical procedures to determine their impact on pre-procedural blood product use and post-procedural bleeding events. Studies comparing TEG or ROTEM-guided transfusions with standard-of-care (SOC) prior to non-surgical procedures in adult patients with cirrhosis were included. Primary outcomes were fresh frozen plasma (FFP) and platelet transfusion and secondary outcomes of post-procedure bleeding, transfusion-related complications, and mortality; and were reported as standardized mean differences (SMD) and risk ratios (RR).

RESULTS

Six studies (five randomized controlled trials and one cohort study) involving 367 patients met inclusion criteria. Compared with SOC, TEG/ROTEM-guided transfusions led to an overall decreased number of patients who received FFP transfusions (SMD = -0.93, 95% CI [-1.54, -0.33], p < 0.001) and platelets transfusions (SMD = -1.50, CI [-1.85, -1.15], p < 0.001). Total amount of FFP (SMD-0.86, p < 0.001) and platelet (SMD = -0.99, p < 0.001) transfused in the TEG/ROTEM group were also lower. Decreased pre-procedure transfusion in the TEG/ROTEM group did not result in increased post-procedure bleeding (RR = 0.61, p = 0.09) or in mortality (RR = 0.91, p = 0.93).

CONCLUSION

In patients with cirrhosis, TEG or ROTEM significantly reduces blood product utilization prior to non-surgical procedures, with no increase in post-procedure bleeding or mortality. TEG and ROTEM utilization can promote high-value care and improve transfusion stewardship in this population.

Case Report: Thromboelastography for uremic thrombocytopathy in a patient with COVID-19

Uremia causes several biochemical and physiological impairments that result in the accumulation of toxins with multiple clinical effects. Bleeding is one of the most common complications of acute and chronic renal failure. The pathogenesis of uremic bleeding is multifactorial, of which uremic thrombocytopathy is the most described clinically. Various tests have been used to evaluate bleeding diathesis in these patients including bleeding time, prothrombin time, activated partial thromboplastin time, and international normalized ratio, but there are only a few studies that use thromboelastography as a point-of-care test to identify platelet dysfunction. In addition, COVID-19 increases hemorrhagic complications due to platelet dysfunction or hemostasis exhaustion. COVID-19 could also potentially cause platelet dysfunction as a secondary consequence of acute kidney injury. There are only a few studies reporting the use of thromboelastography in COVID-19-induced hypercoagulability, but not in diagnosing or managing platelet-related abnormalities. We present a patient with COVID-19 who developed acute kidney injury in the hospital and retroperitoneal hemorrhage from uremic platelet dysfunction. We used point-of-care thromboelastography with platelet mapping to determine uremic platelet dysfunction.

Thromboelastometry Predicts Thromboembolic Events, Hospital Length of Stay, and Mortality in Patients with COVID-19 Infection and Mild Hypoxemia: A Prospective Observational Study

Background

The aim of this study was to assess changes in hemostasis and associated outcome of hospitalized patients with COVID-19 infection and mild hypoxemia.

Methods

Adult patients with COVID-19 infection and hypoxemia admitted to ICU were included in this prospective observational study. The primary outcome was defined as an unfavorable course of the disease if a patient: (1) developed a thromboembolic event while receiving anticoagulation prophylaxis, (2) had prolonged ICU stay, or (3) died. Demographic data, laboratory parameters and thromboelastometry (ROTEM) test results were collected.

Results

Twenty-five patients were recruited into the study. There were 16 patients with an unfavorable course of the disease. Compared to the 9 patients in the favorable course group, patients with an unfavorable course had a lower platelet count, median difference of 154 (95% CI, 26 to 223 x10⁹/L), P = 0.012, and lower clot firmness parameters in EXTEM assay: amplitude at 20 minutes (A20), median difference of 7 (95% CI, 2 to 11) P = 0.006, maximum clot firmness (MCF), median difference of 6 (95% CI, 3 to 10) P = 0.006 and area under the curve (AUC) with a median difference of 671 (95% CI, 244 to 1029) P = 0.005. They also demonstrated suppression of fibrinolysis: higher lysis index 60, median difference of -3 (95% CI, -6 to 0), P = 0.023. Results of functional fibrinogen (FIBTEM) assay were similar between the groups.

Conclusion

The platelet count and the results of EXTEM assay, but not FIBTEM assay, were associated with the difference in clinical outcome among patients with COVID-19 infection and hypoxemia. The role of platelets in the outcome of COVID-19 infection calls for further investigation. Future studies on adjusting anticoagulant therapy based on the results of viscoelastic testing may be beneficial.

How we manage blood product support and coagulation in the adult patient requiring extracorporeal membrane oxygenation

Use of extracorporeal membrane oxygenation (ECMO) is increasing among critically ill adults with cardiac and/or respiratory failure. Use of ECMO is associated with hemostatic alterations requiring use of anticoagulation and blood product support. There are limited guidelines to direct transfusion management in the adult patient supported with ECMO. The objective of this article is to describe (1) the role of the transfusion service in providing transfusion support and current understanding of transfusion thresholds, (2) the complexities of monitoring anticoagulation, and (3) the consideration regarding additional factor concentrates and antifibrinolytics within the context of ECMO support. The information provided should assist ECMO care teams in informing transfusion and anticoagulation practice while highlighting key areas for future research and collaboration.

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.

Coagulopathies in Intensive Care Medicine: Balancing Act between Thrombosis and Bleeding

Patient Blood Management advocates an individualized treatment approach, tailored to each patient's needs, in order to reduce unnecessary exposure to allogeneic blood products. The optimization of hemostasis and minimization of blood loss is of high importance when it comes to critical care patients, as coagulopathies are a common phenomenon among them and may significantly impact morbidity and mortality. Treating coagulopathies is complex as thrombotic and hemorrhagic conditions may coexist and the medications at hand to modulate hemostasis can be powerful. The cornerstones of coagulation management are an appropriate patient evaluation, including the individual risk of bleeding weighed against the risk of thrombosis, a proper diagnostic work-up of the coagulopathy's etiology, treatment with targeted therapies, and transfusion of blood product components when clinically indicated in a goal-directed manner. In this article, we will outline various reasons for coagulopathy in critical care patients to highlight the aspects that need special consideration. The treatment options outlined in this article include anticoagulation, anticoagulant reversal, clotting factor concentrates, antifibrinolytic agents, desmopressin, fresh frozen plasma, and platelets. This article outlines concepts with the aim of the minimization of complications associated with coagulopathies in critically ill patients. Hereditary coagulopathies will be omitted in this review.

Obstetrical Hemorrhage

Obstetric hemorrhage is a leading cause of morbidity and mortality. Prevention includes identifying patients with risk factors and actively managing the third stage of labor. The anesthesiologist should be ready to manage hemorrhage with general strategies as well as strategies tailored to the specific cause of hemorrhage. Both neuraxial anesthesia and general anesthesia are appropriate in different situations. Treatments proven to be effective include increasing the oxytocin infusion, administering tranexamic acid early, guiding transfusion with point-of-care tests, and using cell salvage. Utilization of protocols and checklists within systems that encourage effective communication between teams should be implemented.

Models to predict the probability for intraoperative RBC transfusion during lumbar spinal stenosis and femoral fracture surgeries in aged patients

OBJECTIVE

The goal of this study was to predict the probability of transfusion of red blood cells and the volume of blood consumption based on the clinical characteristics of patients before surgery.

METHODS

The medical records of 565 patients over 65 years old who underwent posterior lumbar surgery and 586 patients over 65 years old receiving femoral fracture surgery were reviewed. The clinical characteristics of the patients were subjected to multivariate regression analysis. The scores of these factors' influences on intraoperative red blood cells infusion were based on the odds ratio of each multivariate risk factor. Non-linear regression was performed to predict the probability of intraoperative blood transfusion and the volume of blood used for patients with different scores.

RESULTS

The factors that significantly influenced blood use during lumbar spinal stenosis and femoral fracture surgery in aged patients(P < 0.05) included age, body mass index, abnormal coagulation function, preoperative hemoglobin, administration of antithrombotic drugs, multisegmental lesions of the lumbar spine, femoral shaft fracture, secondary lumbar surgery and the time from fracture to surgery exceeding 48 h. According to our risk scoring system, patients of posterior lumbar surgery scored 0-10 and patients of femoral fracture had a score of 0-12. More than 50 % of patients receiving an intraoperative red blood cells transfusion during surgery scored>1.

CONCLUSION

The scoring system can be used as a predictive model for the probability of red blood cells transfusion and the blood volume in aged patients undergoing lumbar spinal stenosis and femoral fracture surgeries.

TEG® and ROTEM® Traces: Clinical Applications of Viscoelastic Coagulation Monitoring in Neonatal Intensive Care Unit

The concentration of the majority of hemostatic proteins differs considerably in early life, especially in neonates compared to adulthood. Knowledge of the concept of developmental hemostasis is an essential prerequisite for the proper interpretation of conventional coagulation tests (CCT) and is critical to ensure the optimal diagnosis and treatment of hemorrhagic and thrombotic diseases in neonatal age. Viscoelastic tests (VETs) provide a point-of-care, real-time, global, and dynamic assessment of the mechanical properties of the coagulation system with the examination of both cellular and plasma protein contributions to the initiation, formation, and lysis of clots. In this work, we provide a narrative review of the basic principles of VETs and summarize current evidence regarding the two most studied point-of-care VETs, thromboelastography (TEG^®) and rotational thromboelastometry (ROTEM^®), in the field of neonatal care. A literature analysis shows that viscoelastic hemostatic monitoring appears to be a useful additive technique to CCT, allowing targeted therapy to be delivered quickly. These tools may allow researchers to determine the neonatal coagulation profile and detect neonatal patients at risk for postoperative bleeding, coagulation abnormalities in neonatal sepsis, and other bleeding events in a timely manner, guiding transfusion therapies using the goal-oriented transfusion algorithm. However, diagnosis and treatment algorithms incorporating VETs for neonatal patients in a variety of clinical situations should be developed and applied to improve clinical outcomes. Further studies should be performed to make routinary diagnostic and therapeutic application possible for the neonatal population.

Perioperative Viscoelastic Assay Use for Monitoring Coagulation Among US Liver Transplantation Centers

BACKGROUND

Viscoelastic assay has been used in liver transplantation since 1985 and shown to be beneficial in detecting coagulopathy and to guide transfusion. The objective of this study was to review and evaluate the current uses of viscoelastic assay among US liver transplantation programs.

METHODS

Anesthesia program directors at all 137 liver transplantation centers in the United States were contacted via email and asked to complete a 21-item survey. The primary outcome measure was the percentage of viscoelastic assay used in the perioperative management of liver transplantation. Secondary outcome measures were institutional demographics, physician training level, and device demographics.

RESULTS

Sixty-one of 137 (46%) centers responded. Liver transplantations were performed in the university setting at 48 of the 61 centers (77%), with a modal value of 11 to 50 liver transplantations a year and 74% in adult patients only. Most of the institutions (n = 57, 92%) had access to either rotational thromboelastometry or thrombelastography during liver transplantation. Most centers (n = 54; 87%) also used viscoelastic monitoring routinely (>60% of the time), including 42 (67.7%) that always used viscoelastic assay intraoperatively during liver transplantation. Thirty-five centers (59%) used it preoperatively, and 51 (84%) used it postoperatively. Most viscoelastic assay users (68%) learned how to use it through self-education and 10.5% learned during their fellowship or from a superuser or colleagues.

CONCLUSION

Currently, viscoelastic monitoring is widely available and routinely used in most US liver transplantation centers regardless of university or private practice setting, but training in it is limited. Only 21.1% of respondents reported that they received any type of official training in viscoelastic assay interpretation.

Utility of Viscoelastic Tests to Predict Flap Thrombosis: A Systematic Review

Background:

Flap thrombosis is a rare but devastating complication in microsurgery. Preoperative identification of patients at increased risk for microvascular thrombosis remains challenging. Viscoelastic testing (VET) provides a comprehensive evaluation of the clotting process and can effectively identify hypercoagulability. However, the utility of VET in microvascular reconstruction remains unclear.

Methods:

A systematic review of the association between VET and pedicle thrombosis and free flap loss was performed in accordance with Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines. Identified studies were reviewed independently by two authors for pertinent data.

Results:

Six studies met inclusion criteria. Heterogenous study design and outcome reporting complicated direct comparisons and precluded a formal meta-analysis. Four studies found a statistically significant relationship between VET results and flap thrombosis or flap loss. The maximum clot strength and the fibrinogen-to-platelet ratio (FPR) were key viscoelastic parameters in these studies, both representing a measure of maximal clot strength. Specifically, an elevated FPR (>42%) generated a sensitivity and specificity for flap loss ranging from 57% to 75% and 60% to 82%, respectively. Notably, the negative predictive value for flap failure with a normal preoperative FPR was greater than 90% in all studies reporting a correlation. The remaining two studies reported no predictive value for VET with respect to flap failure or pedicle thrombosis.

Conclusion:

The results of this review suggest that VET, particularly parameters relating to clot strength, may help clinicians identify patients at risk for flap thrombosis. However, uncontrolled and heterogenous reporting limit definitive conclusions, and high-quality diagnostic studies are needed to better determine the clinical utility of viscoelastic testing for free flap patients.

Effects of an Animated Blood Clot Technology (Visual Clot) on the Decision-Making of Users Inexperienced in Viscoelastic Testing: Multicenter Trial

BACKGROUND

Viscoelastic test-guided coagulation management has become increasingly important in assessing hemostasis. We developed Visual Clot, an animated, 3D blood clot that illustrates raw rotational thromboelastometry (ROTEM) parameters in a user-centered and situation awareness-oriented method.

OBJECTIVE

This study aimed to evaluate the applicability of Visual Clot by examining its effects on users that are novices in viscoelastic-guided resuscitation.

METHODS

We conducted an investigator-initiated, international, multicenter study between September 16, 2020, and October 6, 2020, in 5 tertiary care hospitals in central Europe. We randomly recruited medical students and inexperienced resident physicians without significant prior exposure to viscoelastic testing. The 7 participants per center managed 9 different ROTEM outputs twice, once as standard ROTEM tracings and once as the corresponding Visual Clot. We randomly presented the 18 viscoelastic cases and asked the participants for their therapeutic decisions. We assessed the performance, diagnostic confidence, and perceived workload in managing the tasks using mixed statistical models and adjusted for possible confounding factors.

RESULTS

Analyzing a total of 630 results, we found that the participants solved more cases correctly (odds ratio [OR] 33.66, 95% CI 21.13-53.64; P<.001), exhibited more diagnostic confidence (OR 206.2, 95% CI 93.5-454.75; P<.001), and perceived less workload (coefficient -41.63; 95% CI -43.91 to -39.36; P<.001) using Visual Clot compared to using standard ROTEM tracings.

CONCLUSIONS

This study emphasizes the practical benefit of presenting viscoelastic test results in a user-centered way. Visual Clot may allow inexperienced users to be involved in the decision-making process to treat bleeding-associated coagulopathy. The increased diagnostic confidence, diagnostic certainty, reduced workload, and positive user feedback associated with this visualization may promote the further adoption of viscoelastic methods in diverse health care settings.

Patient blood management in India - Review of current practices and feasibility of applying appropriate standard of care guidelines. A position paper by an interdisciplinary expert group

In a developing country like India, with limited resources and access to healthcare facilities, dealing with massive hemorrhage is a major challenge. This challenge gets compounded by pre-existing anemia, hemostatic disorders, and logistic issues of timely transfer of such patients from peripheral hospitals to centers with adequate resources and management expertise. Despite the awareness amongst healthcare providers regarding management modalities of bleeding patients, no uniform Patient Blood Management (PBM) or perioperative bleeding management protocols have been implemented in India, yet. In light of this, an interdisciplinary expert group came together, comprising of experts working in transfusion medicine, hematology, obstetrics, anesthesiology and intensive care, to review current practices in management of bleeding in Indian healthcare institutions and evaluating the feasibility of implementing uniform PBM guidelines. The specific intent was to perform a gap analysis between the ideal and the current status in terms of practices and resources. The expert group identified interdisciplinary education in PBM and bleeding management, bleeding history, viscoelastic and platelet function testing, and the implementation of validated, setting-specific bleeding management protocols (algorithms) as important tools in PBM and perioperative bleeding management. Here, trauma, major surgery, postpartum hemorrhage, cardiac and liver surgery are the most common clinical settings associated with massive blood loss. Accordingly, PBM should be implemented as a multidisciplinary and practically applicable concept in India in a timely manner in order to optimize the use the precious resource blood and to increase patients' safety.

Viscoelastic Coagulation Monitor as a Novel Device to Assess Coagulation at the Bedside. A Single-Center Experience During the COVID-19 Pandemic

Viscoelastic coagulation monitor (VCM) is a portable device developed to evaluate the viscoelastic properties of whole blood activated by contact with glass. In this study, VCM was employed to analyze the viscoelastic profiles of 36 COVID-19 intensive care patients. Full anticoagulant dose heparin (unfractionated [UFH]; low molecular weight [LMWH]) was administrated to all patients. The association between VCM and laboratory parameters was retrospectively analyzed. The administration of UFH-influenced VCM parameters prolonging clotting time (CT) and clot formation time (CFT) and reducing angle (alpha) and amplitudes of the VCM tracings (A10, A20, and maximum clot firmness [MCF]) compared with LMWH therapy. A tendency toward hypercoagulation was observed by short CT and CFT in patients receiving LMWH. Clotting time was correlated with UFH dose (Spearman's rho = 0.48, p ≤ 0.001), and no correlation was found between CT and LMWH. All VCM tracings failed to show lysis at 30 and 45 minutes, indicating the absence of fibrinolysis. A10, A20, and MCF exhibited very-good to good diagnostic accuracy for detecting platelet count and fibrinogen above the upper reference limit of the laboratory. In conclusion, VCM provided reliable results in COVID-19 patients and was easy to perform with minimal training at the bedside.

Viscoelastic Haemostatic Assays in Cardiovascular Critical Care

The initiation and management of anticoagulation is a fundamental practice for a wide variety of indications in cardiovascular critical care, including the management of patients with acute MI, stroke prevention in patients with AF or mechanical valves, as well as the prevention of device thrombosis and thromboembolic events with the use of mechanical circulatory support and ventricular assist devices. The frequent use of antiplatelet and anticoagulation therapy, in addition to the presence of concomitant conditions that may lead to a propensity to bleed, such as renal and liver dysfunction, present unique challenges. The use of viscoelastic haemostatic assays provides an additional tool allowing clinicians to strike a delicate balance of attaining adequate anticoagulation while minimising the risk of bleeding complications. In this review, the authors discuss the role that viscoelastic haemostatic assay plays in cardiac populations (including cardiac surgery, heart transplantation, extracorporeal membrane oxygenation, acute coronary syndrome and left ventricular assist devices), and identify areas in need of further study.

Physicians' perceptions regarding acute bleeding management: an international mixed qualitative quantitative study

Background

Acute bleeding is an omnipresent challenge for all physicians. Uncontrolled hemorrhage is the most common preventable cause of death after trauma worldwide. In different surgical disciplines, hemorrhage represents an independent risk factor for increased postoperative morbimortality, directly affecting patients’ outcomes. This study asked anesthesiologists about their personal perceived challenges when treating bleeding patients.

Methods

This investigator-initiated, prospective, international, dual-center, mixed qualitative and quantitative study interrogated anesthesiologists about what they found easy and what difficult in treating acutely bleeding patients. Following the template approach for qualitative research, we identified major and minor topics through free inductive coding and word count. In a second step, we derived ten statements from the participants’ answers. Using a field survey, we then asked the participants to rate their level of agreement with the derived statements. We analyzed the answers using one sample Wilcoxon test and the Mann-Whitney test.

Results

We included a total of 84 physicians in the qualitative interrogations and a different group of 42 anesthesiologists in the quantitative part. We identified 11 major topics and 19 associated subtopics. The main topics and the degree of agreement (here as agree or strongly agree) were as follows: “Complexity of the topic” (52.4% agreed to find the topic complex), “Cognitive aids” (92.9% agreed to find them helpful), “Time management” (64.3% agreed to feeling time pressure), “Human factors” (95.2% agreed that human factors are essential), “Resources” (95.2% agreed that resources are essential), “Experience” and “Low frequency of cases” (57.1% agreed to lack practice), “Diagnostic methods” (31.0% agreed that the interpretation of test results is difficult), “Anticoagulation” (85.7% agreed to it being difficult), “Treatment” (81.0% agreed to knowing the first therapeutic steps), and “Nothing”.

Conclusions

Anesthesiologists in two large tertiary care facilities in different parts of the world found coagulation management, especially in anticoagulated patients, complex. We identified the delayed diagnostic test results and their interpretation as challenges. Resources, treatment protocols and human factors such as team communication were perceived to facilitate management. Future studies should explore the challenges in smaller hospitals and other parts of the world and test new technologies addressing the identified difficulties.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01269-x.

Variations and obstacles in the use of coagulation factor concentrates for major trauma bleeding across Europe: outcomes from a European expert meeting

Purpose

Trauma is a leading cause of mortality, with major bleeding and trauma-induced coagulopathy (TIC) contributing to negative patient outcomes. Treatments for TIC include tranexamic acid (TXA), fresh frozen plasma (FFP), and coagulation factor concentrates (CFCs, e.g. prothrombin complex concentrates [PCCs] and fibrinogen concentrate [FCH]). Guidelines for TIC management vary across Europe and a clear definition of TIC is still lacking.

Methods

An advisory board involving European trauma experts was held on 02 February 2019, to discuss clinical experience in the management of trauma-related bleeding and recommendations from European guidelines, focusing on CFC use (mainly FCH). This review summarises the discussions, including TIC definitions, gaps in the guidelines that affect their implementation, and barriers to use of CFCs, with suggested solutions.

Results

A definition of TIC, which incorporates clinical (e.g. severe bleeding) and laboratory parameters (e.g. low fibrinogen) is suggested. TIC should be treated immediately with TXA and FCH/red blood cells; subsequently, if fibrinogen ≤ 1.5 g/L (or equivalent by viscoelastic testing), treatment with FCH, then PCC (if bleeding continues) is suggested. Fibrinogen concentrate, and not FFP, should be administered as first-line therapy for TIC. Several initiatives may improve TIC management, with improved medical education of major importance; generation of new and stronger data, simplified clinical practice guidance, and improved access to viscoelastic testing are also critical factors.

Conclusions

Management of TIC is challenging. A standard definition of TIC, together with initiatives to facilitate effective CFC administration, may contribute to improved patient care and outcomes.

Reference Values of Thrombolastometry Parameters in Healthy Term Neonates

Background: Thromboelastometry (ROTEM), as a point of care test, is an attractive tool for rapid evaluation of hemostasis. Currently, no reference ranges exist for all ROTEM assays in neonates, limiting its use in this vulnerable population. The aim of the present study was: (1) to establish reference ranges for standard extrinsically activated (EXTEM), intrinsically activated (INTEM), and fibrinogen polymerization (FIBTEM) ROTEM assays in whole blood samples of healthy term neonates; (2) to determine the impact of gender, delivery mode, and hematocrit on ROTEM parameters. Methods: EXTEM, INTEM, and FIBTEM ROTEM assays were performed simultaneously with complete blood count in 215 healthy term neonates. Results: Reference ranges (2.5th and 97.5th percentiles) were obtained for clotting time (CT), clot formation time (CFT), α-angle, clot firmness at 10 min (A10), maximum clot firmness (MCF), and lysis index at 60 min (LI60, %). Reference ranges for EXTEM were CT 38–78 s, CFT 49–148 s, A10 40–65 mm, and MCF 47–69 mm, LI60 83–98%. For INTEM, CT 134–270 s, CFT 50–142 s, A10 41–63 mm, and MCF 48–67 mm, LI60 85–97%, and finally, for FIBTEM: CT 36–85 s, A10 9–25 mm and MCF 10–26 mm, LI60 92–100%. Hematocrit values were positively correlated with CT, CFT and negatively with A10, MCF values. Conclusion: This study provides, for the first time, reference ranges for ROTEM EXTEM/INTEM/FIBTEM values simultaneously in healthy term neonates. The combined evaluation of ROTEM tests increases its diagnostic accuracy, contributing to the expansion of ROTEM use in the neonatal population.

Modern Management of Bleeding, Clotting, and Coagulopathy in Trauma Patients: What Is the Role of Viscoelastic Assays?

Purpose of Review

The purpose of this review is to briefly outline the current state of hemorrhage control and resuscitation in trauma patients with a specific focus on the role viscoelastic assays have in this complex management, to include indications for use across all phases of care in the injured patient.

Recent Findings

Viscoelastic assay use to guide blood-product resuscitation in bleeding trauma patients can reduce mortality by up to 50%. Viscoelastic assays also reduce total blood products transfused, reduce ICU length of stay, and reduce costs. There are a large number of observational and retrospective studies evaluating viscoelastic assay use in the initial trauma resuscitation, but only one randomized control trial. There is a paucity of data evaluating use of viscoelastic assays in the operating room, post-operatively, and during ICU management in trauma patients, rendering their use in these settings extrapolative/speculative based on theory and data from other surgical disciplines and settings.

Summary

Both hypocoagulable and hypercoagulable states exist in trauma patients, and better indicate what therapy may be most appropriate. Further study is needed, particularly in the operating room and post-operative/ICU settings in trauma patients.

Hemostatic Testing in Critically Ill Infants and Children

Children with critical illness frequently manifest imbalances in hemostasis with risk of consequent bleeding or pathologic thrombosis. Traditionally, plasma-based tests measuring clot formation by time to fibrin clot generation have been the "gold standard" in hemostasis testing. However, these tests are not sensitive to abnormalities in fibrinolysis or in conditions of enhanced clot formation that may lead to thrombosis. Additionally, they do not measure the critical roles played by platelets and endothelial cells. An added factor in the evaluation of these plasma-based tests is that in infants and young children plasma levels of many procoagulant and anticoagulant proteins are lower than in older children and adults resulting in prolonged clot generation times in spite of maintaining a normal hemostatic "balance." Consequently, newer assays directly measuring thrombin generation in plasma and others assessing the stages hemostasis including clot initiation, propagation, and fibrinolysis in whole blood by viscoelastic methods are now available and may allow for a global measurement of the hemostatic system. In this manuscript, we will review the processes by which clots are formed and by which hemostasis is regulated, and the rationale and limitations for the more commonly utilized tests. We will also discuss selected newer tests available for the assessment of hemostasis, their "pros" and "cons," and how they compare to the traditional tests of coagulation in the assessment and management of critically ill children.

Minimizing Blood Loss in Spine Surgery

STUDY DESIGN

Broad narrative review.

OBJECTIVE

To review and summarize the current literature on guidelines, outcomes, techniques and indications surrounding multiple modalities of minimizing blood loss in spine surgery.

METHODS

A thorough review of peer-reviewed literature was performed on the guidelines, outcomes, techniques, and indications for multiple modalities of minimizing blood loss in spine surgery.

RESULTS

There is a large body of literature that provides a consensus on guidelines regarding the appropriate timing of discontinuation of anticoagulation, aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), and herbal supplements prior to surgery. Additionally, there is a more heterogenous discussion the utility of preoperative autologous blood donation facilitated by erythropoietin and iron supplementation for healthy patients slated for procedures with high anticipated blood loss and for whom allogeneic transfusion is likely. Intraoperative maneuvers available to minimize blood loss include positioning and maintaining normothermia. Tranexamic acid (TXA), bipolar sealer electrocautery, and topical hemostatic agents, and hypotensive anesthesia (mean arterial pressure (MAP) <65 mm Hg) should be strongly considered in cases with larger exposures and higher anticipated blood loss. There is strong level 1 evidence for the use of TXA in spine surgery as it reduces the overall blood loss and transfusion requirements.

CONCLUSION

As the volume and complexity of spinal procedures rise, intraoperative blood loss management has become a pivotal topic of research within the field. There are many tools for minimizing blood loss in patients undergoing spine surgery. The current literature supports combining techniques to use a cost- effective multimodal approach to minimize blood loss in the perioperative period.

Approach to the Coagulopathic Patient in the Intensive Care Unit

Key learning objectives:

Evaluating patients with coagulopathy in intensive care

Managing coagulopathy in intensive care

Understand the complications and limitations of various therapies

How to cite this article: Singh MY. Approach to the Coagulopathic Patient in the Intensive Care Unit. Indian J Crit Care Med 2019;23(Suppl 3):S215–S220.

Advance in the Management of Sepsis-Induced Coagulopathy and Disseminated Intravascular Coagulation. J Clin Med. 2019;8. [PMID: 31121897 PMCID: PMC6572234 DOI: 10.3390/jcm8050728]

Coagulopathy commonly occurs in sepsis as a critical host response to infection that can progress to disseminated intravascular coagulation (DIC) with an increased mortality. Recent studies have further defined factors responsible for the thromboinflammatory response and intravascular thrombosis, including neutrophil extracellular traps, extracellular vesicles, damage-associated molecular patterns, and endothelial glycocalyx shedding. Diagnosing DIC facilitates sepsis management, and is associated with improved outcomes. Although the International Society on Thrombosis and Haemostasis (ISTH) has proposed criteria for diagnosing overt DIC, these criteria are not suitable for early detection. Accordingly, the ISTH DIC Scientific Standardization Committee has proposed a new category termed “sepsis-induced coagulopathy (SIC)” to facilitate earlier diagnosis of DIC and potentially more rapid interventions in these critically ill patients. Therapy of SIC includes both treatment of the underlying infection and correcting the coagulopathy, with most therapeutic approaches focusing on anticoagulant therapy. Recently, a phase III trial of recombinant thrombomodulin was performed in coagulopathic patients. Although the 28-day mortality was improved by 2.6% (absolute difference), it did not reach statistical significance. However, in patients who met entry criteria for SIC at baseline, the mortality difference was approximately 5% without increased risk of bleeding. In this review, we discuss current advances in managing SIC and DIC.

Closing the gap - detection of clinically relevant von Willebrand disease in emergency settings through an improved algorithm based on rotational Thromboelastometry

Background

Hemorrhage and blood loss are still among the main causes of preventable death. Global hemostatic assays are useful point-of-care test (POCT) devices to rapidly detect cumulative effects of plasma factors and platelets on coagulation. Thromboelastography (TEG) and Thromboelastometry (ROTEM) are established methods in many anesthesiological departments for guided hemostatic treatment. However, von Willebrand disease remains undetected by standard ROTEM, especially during emergency care, despite being the most prevalent congenital hemostatic disorder.

Methods

In our monocentric cohort pilot study we focused on hemostatic challenges associated with von Willebrand disease. Twenty-seven patients with suspected von Willebrand disease were included. We modified the routine ROTEM assay by adding a preincubation with ristocetin and commercially available plasma-derived von Willebrand factor to identify clinically relevant von Willebrand disease (VWD).

Results

Addition of von Willebrand factor to the ristocetin assay of a VWD type 3 patient restored the reaction of the whole blood probe to match the response of a healthy person. Our modified ROTEM assay with ristocetin (Ricotem) showed that all high responders (n = 7) had VWD. In the low responder group (n = 16) – 10 of 16 had VWD and in the normal responder group (n = 5), 2 of 5 had mild type 1 VWD.

Conclusions

This new modification of the standard ROTEM assay enables the detection of otherwise unnoticed critical von Willebrand disease based on alterations in clot formation and might serve as a novel approach to reliably assess severe VWD patients by platelet-mediated blood clotting in an emergency setting. We recommend incorporating this new VWD-focused screening tool into the current ROTEM-based management algorithm of acute microvascular bleeding.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0672-8) contains supplementary material, which is available to authorized users.

An introduction to point-of-care testing in extracorporeal circulation and LVADs

There is a delicate balance between bleeding and clotting in patients on circuits such as ventricular assist devices or extracorporeal membrane oxygenation. Traditional coagulation tests, prothrombin time, activated partial thromboplastin time, and anti-factor Xa levels, are used to monitor patients on these devices. However, turnaround times and inability to assess global hemostasis, including platelets and fibrinogen have contributed to a recognition that faster, accurate, and more informative coagulation tests are needed. Activated clotting time is used to monitor heparin in patients on circuits and has the advantages of being a near-patient point-of-care test. However, its utility is limited to heparin monitoring. Viscoelastic tests (thromboelastometry and thromboelastography) are global, whole-blood coagulation tests, and whole-blood platelet aggregometry evaluates platelet function. Ideally, these tests can ensure that patients are within the therapeutic range of their antithrombotic medications, identify patients at risk for hemorrhagic or thrombotic complications, and guide management of acute bleeding complications. This ideal is currently hampered by a lack of studies that delineate clear ranges that are clinically relevant. Future research is needed to better understand the optimal use of point-of-care coagulation testing in patients on extracorporeal circuits and ventricular assist devices.

The use of viscoelastic haemostatic assays in non-cardiac surgical settings: a systematic review and meta-analysis

BACKGROUND

Thrombelastography (TEG) and rotational thromboelastometry (ROTEM) are viscoelastic haemostatic assays (VHA) which exploit the elastic properties of clotting blood. The aim of this systematic review and meta-analysis was to evaluate the usefulness of these tests in bleeding patients outside the cardiac surgical setting.

MATERIALS AND METHODS

We searched the Cochrane Library, MEDLINE, EMBASE and SCOPUS. We also searched clinical trial registries for ongoing and unpublished studies, and checked reference lists to identify additional studies.

RESULTS

We found 4 randomised controlled trials (RCTs) that met our inclusion criteria with a total of 229 participants. The sample size was small (from 28 to 111 patients) and the follow-up periods very heterogenous (from 4 weeks to 3 years). Pooled data from the 3 trials reporting on mortality (199 participants) do not show any effect of the use of TEG on mortality as compared to standard monitoring (based on the average treatment effect from a fixed-effects model): Risk Ratio (RR) 0.71; 95% Confidence Interval (CI): 0.43 to 1.16. Likewise, the use of VHA does not reduce the need for red blood cells (mean difference -0.64; 95% CI: -1.51 to 0.23), platelet concentrates (mean difference -1.12; 95% CI: -3.25 to 1.02), and fresh frozen plasma (mean difference -0.91; 95% CI: -2.02 to 0.19) transfusion. The evidence on mortality and other outcomes was uncertain (very low-certainty evidence, down-graded due to risk of biases, imprecision, and inconsistency).

CONCLUSIONS

Overall, the certainty of the evidence provided by the trials was too low for us to be certain of the benefits and harms of viscoelastic haemostatic assay in non-cardiac surgical settings. More, larger, and better-designed RCTs should be carried out in this area.