Coagulation tests predict bleeding after cardiopulmonary bypass

Viscoelastic blood coagulation testing system enabled by a non-contact triboelectric angle sensor

Thromboelastography (TEG) remains a convenient and effective viscoelastic blood coagulation testing device for guiding blood component transfusion and assessing the risk of thrombosis. Here, a TEG enabled by a non-contact triboelectric angle sensor (NTAS) with a small size (∼7 cm3) is developed for assessing the blood coagulation system. With the assistance of a superelastic torsion wire structure, the NTAS-TEG realizes the detection of blood viscoelasticity. Benefiting from a grating and convex design, the NTAS holds a collection of compelling features, including accurate detection of rotation angles from -2.5° to 2.5°, high linearity (R 2 = 0.999), and a resolution of 0.01°. Besides, the NTAS exhibits merits of low cost and simplified fabrication. Based on the NTAS-TEG, a viscoelastic blood coagulation detection and analysis system is successfully constructed, which can provide a graph and parameters associated with clot initiation, formation, and stability for clinicians by using 0.36 mL of whole blood. The system not only validates the feasibility of the triboelectric coagulation testing sensor, but also further expands the application of triboelectric sensors in healthcare.

Coagulation Tests and Bleeding Classification After Cardiopulmonary Bypass: A Prospective Study

OBJECTIVE

No recent prospective studies have analyzed the accuracy of standard coagulation tests and thromboelastography (TEG) to identify patients with excessive microvascular bleeding following cardiopulmonary bypass (CPB). The aim of this study was to assess the value of coagulation profile tests, as well as TEG, for the classification of microvascular bleeding after CPB.

DESIGN

A prospective observational study.

SETTING

At a single-center academic hospital.

PARTICIPANTS

Patients ≥18 years of age undergoing elective cardiac surgery.

INTERVENTIONS

Qualitative assessment of microvascular bleeding post-CPB (surgeon and anesthesiologist consensus) and the association with coagulation profile tests and TEG values.

MEASUREMENTS AND MAIN RESULTS

A total of 816 patients were included in the study-358 (44%) bleeders and 458 (56%) nonbleeders. Accuracy, sensitivity, and specificity for the coagulation profile tests and TEG values ranged from 45% to 72%. The predictive utility was similar across tests, with prothrombin time (PT) (62% accuracy, 51% sensitivity, 70% specificity), international normalized ratio (INR) (62% accuracy, 48% sensitivity, 72% specificity), and platelet count (62% accuracy, 62% sensitivity, 61% specificity) displaying the highest performance. Secondary outcomes were worse in bleeders versus nonbleeders, including higher chest tube drainage, total blood loss, transfusion of red blood cells, reoperation rates (p < 0.001, respectively), readmission within 30 days (p = 0.007), and hospital mortality (p = 0.021).

CONCLUSIONS

Standard coagulation tests and individual components of TEG in isolation agree poorly with the visual classification of microvascular bleeding after CPB. The PT-INR and platelet count performed best but had low accuracy. Further work is warranted to identify better testing strategies to guide perioperative transfusion decisions in cardiac surgical patients.

Thromboelastography in the Perioperative Period: A Literature Review

Assessing coagulation status is essential for prompt intervention to reduce morbidity and mortality related to bleeding and thrombotic complications during the perioperative period. Traditional coagulation tests such as platelet count, activated partial thromboplastin time (aPTT), prothrombin time (PT), international normalized ratio (INR), and activated clotting time (ACT) provide only static evaluation. These tests are not designed for assessment of dynamically changing coagulation conditions during the perioperative time. However, viscoelastic coagulation testing such as thromboelastography (TEG) produces a rapid numerical and graphical representation that helps to detect and direct targeted hemostatic therapy. Searching the literature through PubMed, Medline, Ovid, CINAHL, and ClinicalTrials.gov we retrieved 210 studies, which represent the use of TEG in the perioperative period. The included studies were categorized under various settings such as trauma, obstetrics, orthopedics, intensive care unit (ICU), cardiovascular, transplant, and miscellaneous scenarios. TEG showed promising results in trauma surgeries in predicting mortality, hypercoagulability, and bleeding even when it was compared to conventional methods. TEG was also useful in monitoring anticoagulant therapy in orthopedic and obstetric surgeries; however, its role in predicting thrombotic events, hypercoagulability, or complications was questionable. In ICU patients, it showed promising results, especially in the prediction or improvement of sepsis, coagulopathy, thrombotic events, ICU duration, hospital stay, and ventilator duration. TEG parameters effectively predicted hypercoagulation in transplant surgeries. Regarding cardiovascular surgeries, they were effective in the prediction of the need for blood products, coagulopathy, thrombotic events, and monitoring anticoagulation therapy. More randomized clinical trials comparing TEG parameters with standardized tools are needed to produce robust results to standardize its use in different perioperative settings.

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.

Prothrombin Complex Concentrate vs Plasma for Post-Cardiopulmonary Bypass Coagulopathy and Bleeding: A Randomized Clinical Trial

Importance

Post-cardiopulmonary bypass (CPB) coagulopathy and bleeding are among the most common reasons for blood product transfusion in surgical practices. Current retrospective data suggest lower transfusion rates and blood loss in patients receiving prothrombin complex concentrate (PCC) compared with plasma after cardiac surgery.

Objective

To analyze perioperative bleeding and transfusion outcomes in patients undergoing cardiac surgery who develop microvascular bleeding and receive treatment with either PCC or plasma.

Design, Setting, and Participants

A single-institution, prospective, randomized clinical trial performed at a high-volume cardiac surgical center. Patients were aged 18 years or older and undergoing cardiac surgery with CPB. Patients undergoing complex cardiac surgical procedures (eg, aortic replacement surgery, multiple procedures, or repeated sternotomy) were preferentially targeted for enrollment. During the study period, 756 patients were approached for enrollment, and 553 patients were randomized. Of the 553 randomized patients, 100 patients met criteria for study intervention.

Interventions

Patients with excessive microvascular bleeding, a prothombin time (PT) greater than 16.6 seconds, and an international normalized ratio (INR) greater than 1.6 were randomized to receive treatment with either PCC or plasma. The PCC dose was 15 IU/kg or closest standardized dose; the plasma dose was a suggested volume of 10 to 15 mL/kg rounded to the nearest unit.

Main Outcomes and Measures

The primary outcome was postoperative bleeding (chest tube output) from the initial postsurgical intensive care unit admission through midnight on postoperative day 1. Secondary outcomes were PT/INR, rates of intraoperative red blood cell (RBC) transfusion after treatment, avoidance of allogeneic transfusion from the intraoperative period to the end of postoperative day 1, postoperative bleeding, and adverse events.

Results

One hundred patients (mean [SD] age, 66.8 [13.7] years; 61 [61.0%] male; and 1 [1.0%] Black, 1 [1.0%] Hispanic, and 98 [98.0%] White) received the study intervention (49 plasma and 51 PCC). There was no significant difference in chest tube output between the plasma and PCC groups (median [IQR], 1022 [799-1575] mL vs 937 [708-1443] mL). After treatment, patients in the PCC arm had a greater improvement in PT (effect estimate, -1.37 seconds [95% CI, -1.91 to -0.84]; P < .001) and INR (effect estimate, -0.12 [95% CI, -0.16 to -0.07]; P < .001). Fewer patients in the PCC group required intraoperative RBC transfusion after treatment (7 of 51 patients [13.7%] vs 15 of 49 patients [30.6%]; P = .04); total intraoperative transfusion rates were not significantly different between groups. Seven (13.7%) of 51 patients receiving PCCs avoided allogeneic transfusion from the intraoperative period to the end of postoperative day 1 vs none of those receiving plasma. There were no significant differences in postoperative bleeding, transfusions, or adverse events.

Conclusions and Relevance

The results of this study suggest a similar overall safety and efficacy profile for PCCs compared with plasma in this clinical context, with fewer posttreatment intraoperative RBC transfusions, improved PT/INR correction, and higher likelihood of allogeneic transfusion avoidance in patients receiving PCCs.

Trial Registration

ClinicalTrials.gov Identifier: NCT02557672.

Sex-Specific Associations Between Preoperative Anemia and Postoperative Clinical Outcomes in Patients Undergoing Cardiac Surgery

BACKGROUND

Preoperative anemia is common in cardiac surgery, yet there were limited data describing the role of sex in the associations between anemia and clinical outcomes. Understanding these relationships may guide preoperative optimization efforts.

METHODS

This is an observational cohort study of adults undergoing isolated coronary artery bypass grafting or single- or double-valve surgery from 2008 to 2018 at a large tertiary medical center. Multivariable regression assessed the associations between preoperative hemoglobin concentrations and a primary outcome of postoperative acute kidney injury (AKI) and secondary outcomes of perioperative red blood cell (RBC) transfusion, reoperation, vascular complications (ie, stroke, pulmonary embolism, and myocardial infarction), and hospital length of stay (LOS). Each outcome was a single regression model, using interaction terms to assess sex-specific associations between hemoglobin and outcome.

RESULTS

A total of 4117 patients were included (57% men). Linear splines with sex-specific knots (13 g/dL in women and 14 g/dL in men) provided the best overall fit for preoperative hemoglobin and outcome relationships. In women, each 1 g/dL decrease in hemoglobin <13 g/dL was associated with increased odds of AKI (odds ratio = 1.49; 95% confidence interval [CI], [1.23-1.81]; P < .001), and there was no significant association between hemoglobin per 1 g/dL >13 g/dL and AKI (0.90 [0.56-1.45]; P = .67). The association between hemoglobin and AKI in men did not meet statistical significance (1.10 [0.99-1.22]; P = .076, per 1 g/dL decrease <14 g/dL; 1.00 [0.79-1.26]; P = .98 for hemoglobin per 1 g/dL >14 g/dL). In women, lower preoperative hemoglobin (per 1 g/dL decrease <13 g/dL) was associated with increased odds of RBC transfusion (2.90 [2.33-3.60]; P < .001), reoperation (1.27 [1.11-1.45]; P < .001) and a longer hospital LOS (multiplicative increase in geometric mean 1.05 [1.03-1.07]; P < .001). In men, preoperative hemoglobin (per 1 g/dL decrease <14 g/dL) was associated with increased odds of perioperative RBCs (2.56 [2.27-2.88]; P < .001) and longer hospital LOS (multiplicative increase in geometric mean 1.02 [1.01-1.04] days; P < .001) but not reoperation (0.94 [0.85-1.04]; P = .256). Preoperative hemoglobin per 1 g/dL >13 g/dL in women and 14 g/dL in men were associated with lower odds of RBCs transfusion (0.57 [0.47-0.69]; P < .001 and 0.74 [0.60-0.91]; P = .005, respectively).

CONCLUSIONS

Preoperative anemia was associated with inferior clinical outcomes after cardiac surgery. The associations between hemoglobin and outcomes were distinct for women and men, with different spline knot points identified (13 and 14 g/dL, respectively). Clinicians should consider data-driven approaches to determine preoperative hemoglobin values associated with increasing risk for adverse perioperative outcomes across sexes.

The Impact of Thromboelastography on Blood Transfusion Policy in Adult Cardiac Surgery-A Retrospective Observational Study from Eastern India

This study was conducted to determine the impact of thromboelastography (TEG) on blood transfusion policy regarding utilization and preparation of cryoprecipitate in adult cardiac surgery. The differences in total transfusion requirement, length of postoperative ICU stay and 24 h mortality were also studied after introduction of TEG in transfusion protocol. It was a retrospective, single-center, observational study conducted in adult patients underwent cardiac surgery from April 2008 to March 2016. Two thousand patients underwent surgery when TEG was used compared with 1000 control patients before availability of TEG. Significantly more patients in the TEG group versus the control group received cryoprecipitate (41 vs. 7%; p < 0.05), while fewer received a transfusion (60 vs. 87.5%; p < 0.05). Significant increase in cryoprecipitate preparation was observed after introduction of TEG. Patients underwent surgery in TEG group showed substantial reduction in administration of PRBC (2.1 vs. 3.5 U; p < 0.05); FFP (2.4 vs. 3.8 U; p < 0.05) and platelets (1.1 vs. 2.7 U; p < 0.05) compared to control group without compromising the length of ICU stay or postoperative mortality. A TEG-guided approach in adult patients undergoing cardiac surgery may increase the use of cryoprecipitate, while decreasing the overall requirement of blood transfusion.

Comparison of two point of care whole blood coagulation analysis devices and conventional coagulation tests as a predicting tool of perioperative bleeding in adult cardiac surgery-a pilot prospective observational study in Japan

BACKGROUND

It is widely accepted that Point-of Care Test (PoCT) devices are useful in the detection of coagulopathies in situations of massive bleeding such as major cardiac surgery. These devices contribute to the reduction of blood transfusion. However, their implementation remains limited in Japan because of their cost and lack of health insurance support.

STUDY DESIGN AND METHODS

Conventional coagulation tests and thromboelastography (TEG)/Sonoclot values were measured in 50 consecutive cardiac surgery cases. Clinical background information such as operative procedures was obtained from electronic medical records, and the theoretical perioperative total blood loss was calculated by measuring the hemoglobin content and total red blood cell transfusion volume. The correlation between perioperative total blood loss and the measured laboratory values or clinical parameters was evaluated by a multivariate linear regression analysis. The risk factors of the total amount of platelet transfusion and postoperative drain bleeding volume were similarly evaluated.

RESULTS

No significant association between the estimated perioperative total blood loss (eTBL) and the laboratory measurements including conventional coagulation tests, TEG and Sonoclot was observed. On the other hand, postoperative drain bleeding volume was significantly associated with postoperative Sonoclot CR (p = 0.039) as well as preoperative use of oral anticoagulants and cell saver treated blood volume. Platelet transfusion amount was significantly associated with post-CBP PF and time to peak value of Sonoclot (p = 0.014 and 0.001, respectively).

CONCLUSION

Sonoclot measurements may be useful to estimate the risks of postoperative bleeding and platelet transfusion in cardiac surgeries in Japan.

Utility of thromboelastography versus routine coagulation tests for assessment of hypocoagulable state in patients undergoing cardiac bypass surgery

Introduction:

Peri-operative monitoring of coagulation is important to diagnose potential cause of hemorrhage, to manage coagulopathy and guide treatment with blood products in patients undergoing cardiac surgery with cardiopulmonary bypass. This study was done to evaluate usefulness of Thromboelastography (TEG) and routine coagulation tests (RCT) in assessing hemostatic changes and predicting postoperative bleeding in patients undergoing cardiac surgery with cardiopulmonary bypass.

Methods:

Fifty adult patients undergoing cardiac surgery with cardiopulmonary bypass were enrolled in this prospective study. Preoperative and post-operative samples were collected for routine coagulation tests and TEG. Regression analysis and test of significance using Pearson's correlation coefficient was performed to assess correlation between routine coagulation tests and corresponding TEG parameters. Regression analysis was done to study relation between blood loss at 24 hours and various coagulation parameters.

Results:

The Routine coagulation test i.e. PT, INR, APTT showed no significant correlation with corresponding TEG parameters in pre-operative samples. However platelet count significantly correlated (p = 0.004) with MA values in postoperative samples. A significant correlation (p = 0.001) was seen between fibrinogen levels and alpha angles as well as with MA in both baseline preoperative and postoperative samples. TEG parameters R time and MA in postoperative samples were the only parameters that predicted bleeders with fair accuracy.

Conclusion:

Though the techniques of RCT and TEG are different, a few RCT e.g. platelet count and fibrinogen correlated with corresponding TEG parameters i.e. MA and Alpha angle. TEG parameters (R time and MA in postoperative samples) were able to predict blood loss better than RCT.

Coagulopathies in cyanotic cardiac patients: An analysis with three point - of - care testing devices (Thromboelastography, rotational thromboelastometry, and sonoclot analyzer)

Introduction:

In the last few years, viscoelastic point-of-care (POC) coagulation devices such as thromboelastography (TEG), rotational thromboelastometry (ROTEM), and Sonoclot (SON) analyzer have been increasingly used in major surgeries for timely assessment and management of coagulopathies. The aim of the present study was to evaluate coagulation profile of cyanotic cardiac patients with TEG, ROTEM, and SON analyzer. In addition, we assessed the correlation of standard laboratory coagulation tests and postoperative chest drain output (CDO) with the parameters of POC testing devices.

Materials and Methods:

Thirty-five patients of either gender, belonging to the American Society of Anesthesiologists Grade I–III, and undergoing elective cardiac surgery on cardiopulmonary bypass for cyanotic congenital heart disease were included in this study. To identify possible coagulation abnormalities, blood samples for TEG, ROTEM, SON, and standard laboratory coagulation were collected after induction of anesthesia. The correlations between variables were assessed using Pearson's correlation coefficient. P < 0.05 was considered statistically significant.

Results and Discussion:

EXTEM clot time (CT) and clot formation time (CFT) were prolonged in 87% and 45% patients whereas INTEM CT and CFT were prolonged in 36% and 73% patients, respectively. FIBTEM maximum clot firmness (MCF) was decreased in 30% patients. We observed significant correlation between fibrinogen concentration and ROTEM FIBTEM MCF (r = 0.94, P < 0.001). The SON platelet function (SON PF) showed good correlation with platelet count (r = 0.85, P < 0.001). We also found significant correlation between preoperative FIBTEM MCF and CDO in first 4 postoperative hours (r = 0.49, P = 0.004) and 24 postoperative hours (r = 0.52, P = 0.005). Receiver operating characteristic analysis demonstrated that SON PF and TEG maximum amplitude are highly predictive of thrombocytopenia below 100 × 10⁹/L (area under the curve [AUC] - 0.97 and 0.92, respectively), while FIBTEM-MCF is highly predictive of hypofibrinogenemia (fibrinogen <150 mg/dL (AUC, 0.99).

Conclusion:

Cyanotic cardiac patients have preoperative coagulation abnormalities in ROTEM, TEG, and SON parameters. ROTEM FIBTEM is highly predictive of hypofibrinogenemia while SON PF is highly predictive of thrombocytopenia. ROTEM FIBTEM can be studied as a marker of increased postoperative CDO.

The Role of Thromboelastography in Pediatric Patients with Sinusoidal Obstructive Syndrome Receiving Defibrotide

Sinusoidal obstructive syndrome (SOS) is a potentially fatal form of hepatic injury after hematopoietic stem cell transplantation. Patients can develop liver dysfunction, portal hypertension, ascites, coagulopathies, and multisystem organ failure. The mortality rate of severe SOS has been reported as high as 98% by day 100 after transplantation. Defibrotide, which is now approved for the treatment of SOS, has significantly decreased mortality. Defibrotide is a polynucleotide with profibrinolytic, anti-ischemic, and anti-inflammatory activity. These properties can increase the risk of life-threatening bleeding in this patient population. Previous protocols have suggested maintaining international normalized ratio ≤ 1.5, platelets > 30 k/uL, and fibrinogen ≥ 150 mg/dL to minimize this risk of bleeding. However, this can be challenging in fluid-sensitive patients with SOS. Thromboelastography (TEG) is a functional assay that evaluates the balance of procoagulant and anticoagulant proteins. In this series, TEG was used to guide defibrotide therapy as well as blood product transfusions in SOS patients with abnormal coagulation studies. Each patient recovered from SOS and had no bleeding complications. A randomized clinical trial is the next step in supporting the use of TEG in SOS patients with abnormal coagulation studies receiving defibrotide therapy.

The Safety and Efficacy of “Bloodless” Cardiac Surgery

Nearly 20% of blood transfusions in the United States are associated with cardiac surgery. Despite the many blood conservation techniques that are available, safe, and efficacious for patients undergoing cardiac surgery, many of these operations continue to be associated with significant amounts of blood transfusion. Although surgical bleeding after cardiopulmonary bypass is a common problem as reflected by the substantial use of blood products, it is the individual physician and institutional behavior that have been identified as reasons for transfusion and not necessarily patient comorbidity or blood loss. Transfusion rates in cardiac surgery remain high despite major advances in perioperative blood conservation, with large variations among individual centers. The adoption of available blood conservation techniques, either alone or in combination in patients undergoing cardiac surgery, could result in an estimated 75% reduction of unnecessary transfusions. The success of previously reported blood conservations programs in cardiac surgery should call for a reevaluation of allogeneic transfusion practices in patients undergoing cardiac surgery. By applying the numerous reported blood conservation strategies for the management of patients presenting for cardiac surgery, we can preserve our dwindling blood resources and help alleviate some of the direct costs of blood as well as the indirect costs of treating noninfectious and infectious complications of transfusion.

Evidence Based Coagulation Monitors: Heparin Monitoring, Thromboelastography, and Platelet Function

The hemostatic management of patients undergoing cardiac surgery is a unique challenge. Since its inception, cardiopulmonary bypass (CPB) has required meticulous attention to maintaining adequate anticoagulation. New anticoagulants and alternative monitoring techniques present an opportunity to investigate potential advances in the area of anticoagulation for CPB. Hemostasis after CPB is still a vexing problem, and the addition of antiplatelet medication to the platelet defect already incurred during CPB has led to hemorrhagic complications in cardiac surgery. The two opposing processes of anticoagulation and hemostasis must be managed carefully and modified with respect to the patient's hematologic status and desired hemostatic outcome. Cardiac surgical patients consume a much larger fraction of perioperative blood transfusions than the percentage of the surgical population they represent. Thus, during CPB, careful attention must be paid to optimal anticoagulation, platelet quiescence, biocompatible circuitry and interventions, and to monitoring hemostasis. The multifactorial etiology of the CPB-induced hemostatic defect requires a multimodal approach to blood conservation and hemostasis monitoring, including heparin maintenance and sophisticated point-of-care hemostasis monitoring. Each technology has its own attributes and each may be suitable for different populations based upon the expected defects being measured. This article reviews the evidence supporting the use of point-of-care monitors in coagulation and hemostasis management in cardiac surgical patients.

Establishment of reference intervals and transfusion criterion for Sonoclot analysis

Sonoclot analyzer has been widely used in many countries. But the reference intervals provided by the manufacturer were derived from only 45 participants, and there was no cut-off value for transfusion for Sonoclot analysis. This study aimed to establish reference intervals and transfusion criterion for Sonoclot analysis. Volunteers were recruited from healthy Chinese adults and patients undergoing cardiac surgery. Blood samples were withdrawn from forearm vein and measured for activated clotting time (ACT), clot rate (CR), platelet function (PF), activated partial thromboplastin time (APTT), fibrinogen concentration (FIB), and platelet count (PLT). The reference intervals were determined by the nonparametric method. Cut-off values were determined by the receiver operating characteristics curve. A total of 135 healthy volunteers and 281 patients were enrolled. The 95% reference intervals were 96-195 s, 22-51 signal U/min, >1.6 for ACT, CR, PF respectively. In the 281 patients, the results of APTT, FIB, PLT, ACT, CR, and PF ranged from 20.5-300.0 s, 0.28-4.11 g/L, (19.0-387.3)×109/L, 80-514 s, 2.9-74 signal U/min, and 0.1-5.1 respectively. The cut-off values for transfusion were >208, ≤14, and ≤1.3 for ACT, CR, PF respectively. The cut-off values of Sonoclot analysis were within the manufacturer's reference intervals, while they were outside the reference intervals established in this study. The results suggested that the manufacturer's reference intervals were not suitable for Chinese. The reference intervals and cut-off values established in this study will be helpful to Chinese patients.

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

BACKGROUND

Patients with substantive bleeding usually require transfusion and/or (re-)operation. Red blood cell (RBC) transfusion is independently associated with a greater risk of infection, morbidity, increased hospital stay and mortality. ROTEM (ROTEM® Delta, TEM International GmbH, Munich, Germany; www.rotem.de), TEG (TEG® 5000 analyser, Haemonetics Corporation, Niles, IL, USA; www.haemonetics.com) and Sonoclot (Sonoclot® coagulation and platelet function analyser, Sienco Inc., Arvada, CO) are point-of-care viscoelastic (VE) devices that use thromboelastometry to test for haemostasis in whole blood. They have a number of proposed advantages over standard laboratory tests (SLTs): they provide a result much quicker, are able to identify what part of the clotting process is disrupted, and provide information on clot formation over time and fibrinolysis.

OBJECTIVES

This assessment aimed to assess the clinical effectiveness and cost-effectiveness of VE devices to assist with the diagnosis, management and monitoring of haemostasis disorders during and after cardiac surgery, trauma-induced coagulopathy and post-partum haemorrhage (PPH).

METHODS

Sixteen databases were searched to December 2013: MEDLINE (OvidSP), MEDLINE In-Process and Other Non-Indexed Citations and Daily Update (OvidSP), EMBASE (OvidSP), BIOSIS Previews (Web of Knowledge), Science Citation Index (SCI) (Web of Science), Conference Proceedings Citation Index (CPCI-S) (Web of Science), Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), Database of Abstracts of Reviews of Effects (DARE), Health Technology Assessment (HTA) database, Latin American and Caribbean Health Sciences Literature (LILACS), International Network of Agencies for Health Technology Assessment (INAHTA), National Institute for Health Research (NIHR) HTA programme, Aggressive Research Intelligence Facility (ARIF), Medion, and the International Prospective Register of Systematic Reviews (PROSPERO). Randomised controlled trials (RCTs) were assessed for quality using the Cochrane Risk of Bias tool. Prediction studies were assessed using QUADAS-2. For RCTs, summary relative risks (RRs) were estimated using random-effects models. Continuous data were summarised narratively. For prediction studies, the odds ratio (OR) was selected as the primary effect estimate. The health-economic analysis considered the costs and quality-adjusted life-years of ROTEM, TEG and Sonoclot compared with SLTs in cardiac surgery and trauma patients. A decision tree was used to take into account short-term complications and longer-term side effects from transfusion. The model assumed a 1-year time horizon.

RESULTS

Thirty-one studies (39 publications) were included in the clinical effectiveness review. Eleven RCTs (n=1089) assessed VE devices in patients undergoing cardiac surgery; six assessed thromboelastography (TEG) and five assessed ROTEM. There was a significant reduction in RBC transfusion [RR 0.88, 95% confidence interval (CI) 0.80 to 0.96; six studies], platelet transfusion (RR 0.72, 95% CI 0.58 to 0.89; six studies) and fresh frozen plasma to transfusion (RR 0.47, 95% CI 0.35 to 0.65; five studies) in VE testing groups compared with control. There were no significant differences between groups in terms of other blood products transfused. Continuous data on blood product use supported these findings. Clinical outcomes did not differ significantly between groups. There were no apparent differences between ROTEM or TEG; none of the RCTs evaluated Sonoclot. There were no data on the clinical effectiveness of VE devices in trauma patients or women with PPH. VE testing was cost-saving and more effective than SLTs. For the cardiac surgery model, the cost-saving was £43 for ROTEM, £79 for TEG and £132 for Sonoclot. For the trauma population, the cost-savings owing to VE testing were more substantial, amounting to per-patient savings of £688 for ROTEM compared with SLTs, £721 for TEG, and £818 for Sonoclot. This finding was entirely dependent on material costs, which are slightly higher for ROTEM. VE testing remained cost-saving following various scenario analyses.

CONCLUSIONS

VE testing is cost-saving and more effective than SLTs, in both patients undergoing cardiac surgery and trauma patients. However, there were no data on the clinical effectiveness of Sonoclot or of VE devices in trauma patients.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013005623.

FUNDING

The NIHR Health Technology Assessment programme.

Use of human fibrinogen concentrate during proximal aortic reconstruction with deep hypothermic circulatory arrest

OBJECTIVE

Human fibrinogen concentrate (HFC) is approved by the Food and Drug Administration for use at 70 mg/kg to treat congenital afibrinogenemia. We sought to determine whether this dose of HFC increases fibrinogen levels in the setting of high-risk bleeding associated with aortic reconstruction and deep hypothermic circulatory arrest (DHCA).

METHODS

This was a prospective, pilot, off-label study in which 22 patients undergoing elective proximal aortic reconstruction with DHCA were administered 70 mg/kg HFC upon separation from cardiopulmonary bypass (CPB). Fibrinogen levels were measured at baseline, just before, and 10 minutes after HFC administration, on skin closure, and the day after surgery. The primary study outcome was the difference in fibrinogen level immediately after separation from CPB, when HFC was administered, and the fibrinogen level 10 minutes following HFC administration. Additionally, postoperative thromboembolic events were assessed as a safety analysis.

RESULTS

The mean baseline fibrinogen level was 317 ± 49 mg/dL and fell to 235 ± 39 mg/dL just before separation from CPB. After HFC administration, the fibrinogen level rose to 331 ± 41 mg/dL (P < .001) and averaged 372 ± 45 mg/dL the next day. No postoperative thromboembolic complications occurred.

CONCLUSIONS

Administration of 70 mg/kg HFC upon separation from CPB raises fibrinogen levels by approximately 100 mg/dL without an apparent increase in thrombotic complications during proximal aortic reconstruction with DHCA. Further prospective study in a larger cohort of patients will be needed to definitively determine the safety and evaluate the efficacy of HFC as a hemostatic adjunct during these procedures.

Practice guidelines for perioperative blood management: an updated report by the American Society of Anesthesiologists Task Force on Perioperative Blood Management*

The American Society of Anesthesiologists Committee on Standards and Practice Parameters and the Task Force on Perioperative Blood Management presents an updated report of the Practice Guidelines for Perioperative Blood Management.

Supplemental Digital Content is available in the text.

Changes in activated partial thromboplastin time and international normalised ratio after on-pump and off-pump surgical revascularization of the heart

Surgical revascularization of the heart (CABG - coronary artery bypass grafting) is one way of treating coronary heart disease. Bleeding is one of the serious and frequent complications of heart surgery and can result in increased mortality and morbidity. Hemostasis disorder may be secondary consequences of surgical bleeding, preoperative anticoagulant therapy, and the use of cardiopulmonary bypass. Tests used for routine evaluation of the coagulation system are activated partial thromboplastin time (APTT) and international normalized ratio (INR). The study encountered 60 patients who were hospitalized at the Clinic for Cardiovascular Diseases, University Clinical Center Tuzla. Patients underwent elective coronary artery bypass heart surgery either with cardiopulmonary bypass (on-pump CABG) or without it (off-pump CABG). The aim of this study was to compare the changes in coagulation tests (APTT, INR) in patients who were operated on-pump and patients operated off-pump. Our study showed that the values of APTT and INR tend to increase immediately after surgery. Twenty-four hours after surgery these values are declining and they are approaching the preoperative values in all observed patients (p <0.05). Comparing APTT between the groups we found that postoperative APTT levels are significantly higher in the group of patients who underwent surgery with cardiopulmonary bypass (p <0.05). Changes in coagulation tests after surgical revascularization of the heart are more pronounced in patients who were operated with on-pump technique compared to patients operated off-pump technique.

Thromboelastography in off-pump coronary artery bypass grafting

BACKGROUND

Thromboelastography enables complete evaluation of the process of clot initiation, the structural characteristics of the formed clot and its stability. Many previous studies have assessed the predictive role of thromboelastography in on-pump cardiac surgery, but there are no clear guidelines on its use in off-pump coronary artery bypass. The aim of this study was to evaluate the use of thromboelastography and its relevance during the postoperative period following off-pump coronary artery bypass.

METHODS

This was a one-year prospective study on 55 patients undergoing off-pump coronary artery bypass for coronary artery disease. Thromboelastography was performed as a bedside investigation in the cardiothoracic and vascular surgery intensive care unit.

RESULTS

The association between maximum amplitude and total blood loss <500 mL compared to blood loss >500 mL was statistically significant (p < 0.001). Using receiver operator characteristic curve analysis, it was seen that with increasing maximum amplitude values, a decrease in blood loss was observed. A cutoff value of maximum amplitude <49.63 mm was regressed to have a predicted sensitivity of 100% and a predicted specificity of 89.3% for prediction of blood loss >500 mL.

CONCLUSIONS

Thromboelastographic parameters show a reliable correlation with increased blood loss in off-pump coronary artery bypass grafting, and predict patients with an increased chance of blood requirement as well as those at risk of a hypercoagulable state.

Thromboelastography is a suboptimal test for determination of the underlying cause of bleeding associated with cardiopulmonary bypass and may not predict a hypercoagulable state

OBJECTIVES

Patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) are at risk of bleeding. The goal of this investigation was to compare thromboelastography (TEG) with standard coagulation tests (prothrombin time [PT], partial thromboplastin time [PTT], fibrinogen, and D-dimer) in patients with active bleeding.

METHODS

A retrospective study of patients who underwent cardiac surgery with CPB was performed. A second analysis was performed to determine if a shortened TEG R time is associated with thrombosis.

RESULTS

Paired TEG and standard coagulation tests were available from 21 bleeding patients; of the 15 patients with normal TEG values and three with a shortened R time, all had abnormalities of standard coagulation tests. Eighteen of 67 patients who underwent surgery with CPB had an episode of postoperative bleeding. The TEG R time and coagulation index, PT, and PTT collected after CPB were associated with postoperative bleeding in the univariate analysis, but only PT was independently associated with postoperative bleeding in the multivariate analysis. In the second analysis, three of 38 patients with a normal TEG and four of 43 patients with a shortened R time had a thrombotic event during hospitalization (P = 1.00).

CONCLUSIONS

TEG had limited utility in identifying the underlying cause of bleeding and was not predictive of postoperative bleeding associated with cardiac surgery compared with conventional coagulation tests. A shortened TEG R time may not represent a hypercoagulable state.

Comparison of three point-of-care testing devices to detect hemostatic changes in adult elective cardiac surgery: a prospective observational study

Background

Bleeding complications in cardiac surgery may lead to increased morbidity and mortality. Traditional blood coagulation tests are not always suitable to detect rapid changes in the patient's coagulation status. Point-of-care instruments such as the TEG (thromboelastograph) and RoTEM (thromboelastometer) have been shown to be useful as a guide for the clinician in the choice of blood products and they may lead to a reduction in the need for blood transfusion, contributing to better patient blood management.

Methods

The purpose of this study was to evaluate the ability of the TEG, RoTEM and Sonoclot instruments to detect changes in hemostasis in elective cardiac surgery with cardiopulmonary bypass and to investigate possible correlations between variables from these three instruments and routine hematological coagulation tests. Blood samples from thirty-five adult patients were drawn before and after surgery and analyzed in TEG, RoTEM, Sonoclot and routine coagulation tests. Data were compared using repeated measures analysis of variance and Pearson's test for linear correlation.

Results

We found significant changes for all TEG variables after surgery, for three of the RoTEM variables, and for one variable from the Sonoclot. There were significant correlations postoperatively between plasma fibrinogen levels and variables from the three instruments.

Conclusions

TEG and RoTEM may be used to detect changes in hemostasis following cardiac surgery with CPB. Sonoclot seems to be less suitable to detect such changes. Variables from the three instruments correlated with plasma fibrinogen and could be used to monitor treatment with fibrinogen concentrate.

Decreased von Willebrand factor ristocetin cofactor activity and increased ADAMTS13 antigen increase postoperative drainage after coronary artery bypass grafting

OBJECTIVES

Routine coagulation tests and bleed-scores fail to identify patients at risk of excessive postoperative drainage following coronary artery bypass grafting (CABG). We sought to investigate whether lower von Willebrand factor (VWF) and higher ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) are associated with a high postoperative drainage after CABG.

METHODS

In the prospective cohort study, VWF antigen (VWF:Ag), VWF ristocetin cofactor (VWF:RCO), VWF collagen-binding (VWF:CB), ADAMTS13 antigen (ADAMTS13:Ag) and ADAMTS13 activity were measured on the day of elective on-pump CABG in 232 consecutive patients without a prior history of haemorrhagic diathesis, including von Willebrand disease (95% discontinued aspirin preoperatively). Postoperative drainage and blood product use were recorded.

RESULTS

A comparison of extreme drainage quartiles (n=56) showed that individuals with the highest drainage volumes have mean VWF:RCO lower by 19% (P<0.0001), median VWF:Ag lower by 19% (P<0.0001), ADAMTS13:Ag higher by 8% (P=0.0002), ADAMTS13 activity higher by 9% (P=0.01) and fibrinogen lower by 14% (P=0.03) than those with the lowest drainage. Linear regression analysis showed that preoperative VWF:RCO (b=-4.83, P=0.002) and fibrinogen (b=-61.52, P=0.04) are the only independent predictors of postoperative drainage. Multivariate logistic regression demonstrated that preoperative VWF:RCO in the lowest quartile and ADAMTS13:Ag levels in the highest quartile increased the risk of high (≥1000 ml) drainage (odds ratio [95% confidence interval]=4.88 [1.83-13.02], P=0.001 and 3.77 [1.49-9.52], P=0.005; respectively).

CONCLUSIONS

Patients undergoing elective CABG with lower preoperative VWF:RCO are at risk of having larger postoperative drainage, which suggests a novel contributor to increased perioperative bleeding in cardiac surgery.

The effects of pre- and postoperative fibrinogen levels on blood loss after cardiac surgery: a systematic review and meta-analysis

OBJECTIVES

Fibrinogen concentrate is increasingly used in cardiac surgery when bleeding is anticipated or ongoing. Since randomized clinical studies to support this are lacking, it is relevant to know whether lower fibrinogen levels are associated with excessive bleeding. We performed a systematic review and meta-analysis to define the association between fibrinogen levels and blood loss after cardiac surgery.

METHODS

A database search (January 2013) was performed on publications assessing the association between pre- and postoperative fibrinogen levels and postoperative blood loss in adult patients undergoing cardiac surgery. Cohort studies and case-control studies were eligible for inclusion. The main outcome was the pooled correlation coefficient, calculated via Fisher's Z transformation scale, in a random-effects meta-analysis model stratified for the time point at which fibrinogen was measured.

RESULTS

A total of 20 studies were included. The pooled correlation coefficient of studies (n = 9) concerning preoperative fibrinogen levels and postoperative blood loss was -0.40 (95% confidence interval: -0.58, -0.18), pointing towards more blood loss in patients with lower preoperative fibrinogen levels. Among papers (n = 16) reporting on postoperative fibrinogen levels and postoperative blood loss, the pooled correlation coefficient was -0.23 (95% confidence interval: -0.29, -0.16).

CONCLUSIONS

Our meta-analysis indicated a significant but weak-to-moderate correlation between pre- and postoperative fibrinogen levels and postoperative blood loss in cardiac surgery. This moderate association calls for appropriate clinical studies on whether fibrinogen supplementation will decrease postoperative blood loss.

Augmentation of thrombin generation in neonates undergoing cardiopulmonary bypass

INTRODUCTION

Factor concentrates are currently available and becoming increasingly used off-label for treatment of bleeding. We compared recombinant activated factor VII (rFVIIa) with three-factor prothrombin complex concentrate (3F-PCC) for the ability to augment thrombin generation (TG) in neonatal plasma after cardiopulmonary bypass (CPB). First, we used a computer-simulated coagulation model to assess the impact of rFVIIa and 3F-PCC, and then performed similar measurements ex vivo using plasma from neonates undergoing CPB.

METHODS

Simulated TG was computed according to the coagulation factor levels from umbilical cord plasma and the therapeutic levels of rFVIIa, 3F-PCC, or both. Subsequently, 11 neonates undergoing cardiac surgery were enrolled. Two blood samples were obtained from each neonate: pre-CPB and post-CPB after platelet and cryoprecipitate transfusion. The post-CPB products sample was divided into control (no treatment), control plus rFVIIa (60 nM), and control plus 3F-PCC (0.3 IU ml(-1)) aliquots. Three parameters of TG were measured ex vivo.

RESULTS

The computer-simulated post-CPB model demonstrated that rFVIIa failed to substantially improve lag time, TG rate and peak thrombin without supplementing prothrombin. Ex vivo data showed that addition of rFVIIa post-CPB significantly shortened lag time; however, rate and peak were not statistically significantly improved. Conversely, 3F-PCC improved all TG parameters in parallel with increased prothrombin levels in both simulated and ex vivo post-CPB samples.

CONCLUSIONS

Our data highlight the importance of prothrombin replacement in restoring TG. Despite a low content of FVII, 3F-PCC exerts potent procoagulant activity compared with rFVIIa ex vivo. Further clinical evaluation regarding the efficacy and safety of 3F-PCC is warranted.

Roles of thrombelastography and thromboelastometry for patient blood management in cardiac surgery

The value of thrombelastography (TEG) and thromboelastometry (ROTEM) to improve perioperative hemostasis is under debate. We aimed to assess the effects of TEG- or ROTEM-guided therapy in patients undergoing cardiac surgery on the use of allogeneic blood products. We analyzed 12 trials including 6835 patients, 749 of them included in 7 randomized controlled trials (RCTs). We collected data on the amount of transfused allogeneic blood products and on the proportion of patients who received allogeneic blood products or coagulation factor concentrates. Including all trials, the odds ratios (ORs) for transfusion of red blood cell (RBC) concentrates, fresh-frozen plasma (FFP), and platelets were 0.62 (95% confidence interval [CI], 0.56-0.69; P<.001), 0.28 (95% CI, 0.24-0.33; P<.001), and 0.55 (95% CI, 0.49-0.62; P<.001), respectively. However, more than 50% of the patients in this analysis were derived from one retrospective study. Including RCTs only, the ORs for transfusion of RBC, FFP, and platelets were 0.54 (95% CI, 0.38-0.77; P<.001), 0.36 (95% CI, 0.25-0.53; P<.001), and 0.57 (95% CI, 0.39-0.81; P=.002), respectively. The use of coagulation factor concentrates was reported in 6 studies, 2 of them were RCTs. The ORs for the infusion of fibrinogen and prothrombin complex concentrate were 1.56 (95% CI, 1.29-1.87; P<.001) and 1.74 (95% CI, 1.40-2.18; P<.001), respectively. However, frequencies and amounts were similar in the intervention and control group in the 2 RCTs. It is presumed that TEG- or ROTEM-guided hemostatic management reduces the proportion of patients undergoing cardiac surgery transfused with RBC, FFP, and platelets. This presumption is strongly supported by similar ORs found in the analysis including RCTs only. Patient blood management based on the transfusion triggers by TEG or ROTEM appears to be more restrictive than the one based on conventional laboratory testing. However, evidence for improved clinical outcome is limited at this time.

Thromboelastography in the Assessment of Bleeding Following Surgery for Congenital Heart Disease

Background: Perioperative bleeding is common in pediatric cardiac surgery patients. Traditional laboratory tests do not adequately characterize coagulation derangements in patients with bleeding. We sought to establish preoperative thromboelastography parameters in children prior to cardiopulmonary bypass, to compare thromboelastography assessment with standard coagulation parameters postoperatively, and to assess thromboelastography in children with significant hemorrhage. Methods: Sixty patients requiring cardiopulmonary bypass were enrolled in a prospective observational study of perioperative thromboelastography. Thromboelastography measures were obtained preoperatively, intraoperatively after protamine administration, upon admit to the intensive care unit, and when patients were treated for bleeding. Thromboelastography measures were not used for clinical care. Postoperative thromboelastography measurements were compared with the standard coagulation parameters. Intraoperative thromboelastography, postoperative thromboelastography, and clinical outcomes were compared among patients who did and did not have significant postoperative bleeding. Results: Preoperative thromboelastography parameters were similar to other published normal values for pediatric patients. Transfusion recommendations based on thromboelastography measurements were significantly different from those based on the standard coagulation testing. Thromboelastography measures after initial protamine administration were significantly different in patients with postoperative bleeding. This difference was not present upon arrival to the intensive care unit. Patients with significant bleeding tended to cease bleeding when clinical interventions were in agreement with recommendations based on thromboelastography. Conclusions: Pediatric patients with significant postoperative bleeding after surgery are more likely to have abnormal thromboelastography early after cessation of cardiopulmonary bypass. Thromboelastography illustrates derangements in the coagulation system and may aid in the treatment of postoperative bleeding.

Change in hemostatic intervention after implementation of thromboelastometry

OBJECTIVE

To monitor the use of blood products and hemostatic intervention after implementation of thromboelastometry.

DESIGN

Observational prospective study using a historic control.

SETTING

Single-center university hospital.

PARTICIPANTS

Patients undergoing cardiac surgery during 2008 (n = 811) were compared with similar patients in 2009 (n = 865).

INTERVENTIONS

Thromboelastometry was implemented in December 2008. Changes in transfusion of blood products and changes in use of recombinant factor VIIa and fibrinogen were studied.

MEASUREMENTS AND MAIN RESULTS

Use of blood products was not decreased significantly after implementation of thromboelastometry. However, in patients receiving blood products, the units of red blood cells were decreased significantly (p = 0.04). Regarding hemostatic reagents, the use of recombinant factor VIIa was decreased significantly (p = 0.04), and the use of fibrinogen increased significantly (p < 0.001). Most blood products (>70%) were given to a minority of patients (∼10%) in 2008 and 2009. In 2009, thromboelastometry was performed in 146 patients (17%), and the use of blood products (p < 0.0001), recombinant factor VIIa (p < 0.001), and fibrinogen (p < 0.001) was significantly higher compared with patients in whom thromboelastometry was not performed.

CONCLUSIONS

After implementation of thromboelastometry, the use of recombinant factor VIIa was decreased significantly, whereas the use of blood products was not decreased significantly in patients undergoing cardiac surgery.

Treatment and monitoring of coagulation abnormalities in children undergoing heart surgery

Bleeding is a considerable clinical problem during and after pediatric heart surgery. While the primary cause of bleeding is surgical trauma, its treatment is often complicated by the presence of coagulopathy. The principle causes of coagulopathy are discussed to provide a context for treatment. The role of laboratory and point of care tests, which aim to identify the cause of bleeding in the individual patient, is also discussed. An attempt is made to examine the current evidence for available therapies, including use of blood products and, more recently proposed, approaches based on human or recombinant factor concentrates.

Assessment of thrombin generation measured before and after cardiopulmonary bypass surgery and its association with postoperative bleeding

BACKGROUND

Bleeding after cardiopulmonary bypass (CPB) is a major cause of morbidity and mortality and consumes large amounts of blood. Identifying patients at increased risk of bleeding secondary to hemostatic impairment may improve clinical outcomes by allowing early intervention.

METHODS

This present study recruited 77 patients undergoing CPB and measured coagulation screens, coagulation factors, TEG(®), Rotem(®) and thrombin generation (TG) before surgery and 30 min after heparin reversal. The tests were analyzed to investigate whether they identified patients at increased risk of excess bleeding (defined as > 1000 mL) in the first 24 h postoperatively.

RESULTS

Patients who bled > 1000 mL had a lower: platelet count (P < 0.02), factors (F)IX, X and XI (P < 0.005), endogenous thrombin potential (ETP) and an initial rate of TG (P < 0.02) and higher activated partial thromboplastin time (aPTT) (P < 0.001) than patients who bled < 1000 mL. Receiver operating characteristic (ROC) analysis was significant for post-operative TG and aPTT (P < 0.001). Furthermore, reduced pre-operative TG was associated with increased postoperative bleeding (P < 0.02). Pre- and postoperative TG were correlated (ρ = 0.7, P < 0.001). TEG(®), Rotem(®) and prothrombin time (PT) at either time point were not associated with increased bleeding.

CONCLUSION

These data suggest that pre-operative defects in the propagation phase of hemostasis are exacerbated during CPB, contributing to bleeding post-CPB. TG taken both pre- and postoperatively could potentially be used to identify patients at an increased risk of bleeding post-CPB.