Potential value of transfusion protocols in cardiac surgery

Effects of Fibrinogen Concentrate Supplementation on Postoperative Bleeding in Infants Undergoing Complex Cardiac Surgery

The use of allogeneic blood products to restore hemostasis during pediatric cardiac surgery is associated with major risks. Consequently, there has been a growing interest in new patient blood management strategies, such as those based on the use of fibrinogen concentrate (FC). Accumulating evidence has shown FC supplementation to be safe and effective. Nevertheless, no guidelines are available on using FC in the pediatric setting, and few objective evaluations have been provided in clinical practice. The endpoint of this monocenter retrospective study was the hemostatic effect of additional FC in infants undergoing complex cardiac surgery with cardiopulmonary bypass to manage persistent clinically relevant bleeding. After weaning from cardiopulmonary bypass and after protamine administration, patients were transfused with conventional allogeneic products such as packed red blood cells, fresh frozen plasma (FFP), and platelets. In the case of redo surgery, according to the institutional protocol, patients also received tranexamic acid. In case of clinically persistent relevant bleeding, according to the anesthesiologist's judgment and thromboelastography, patients received FC supplementation (group with FC) or further FFP transfusions without receiving FC supplementation (group without FC). The primary endpoint was the hemostatic effects of FC. Secondary endpoints were the functional hypofibrinogenemia threshold value (expressed as maximum amplitude fibrinogen, MA-Fib) and postoperative MA-Fib, fibrinogenemia, intraoperative transfusions, and adverse events (AEs). In total, 139 patients who underwent cardiac surgery with CPB and aged less than 2 years were enrolled: 70 patients received allogeneic blood products and FC supplementation (group FC); 69 patients received allogeneic products without FC supplementation (group without FC). Patients that received FC supplementation were characterized by a significantly longer time of extracorporeal circulation (p < 0.001) and aortic cross-clamping (p < 0.001), a significantly lower minimum temperature (p = 0.011), increased use of concentrated prothrombin complex (p = 0.016) and tranexamic acid (p = 0.010), and a significantly higher amount of packed red blood cells, platelets (p < 0.001) and fresh frozen plasma (p = 0.03). Postoperative bleeding and severe bleeding were not statistically different between patients treated with FC and those not treated with FC supplementation (p = 0.786 and p = 0.695, respectively); after adjustment, a trend toward reduced bleeding can be observed with FC (p = 0.064). Overall, 88% of patients with severe bleeding had MA-Fib < 10 mm; a moderate association between severe bleeding and MA-Fib (odds ratio 1.7, 95% CI 0.5-6.5, p = 0.425) was found. Increased MA-Fib and postoperative fibrinogen were higher in the FC group (p = 0.003 and p < 0.001, respectively) than in FFP. AEs in the FC group were comparable to those observed in less complicated surgeries. Our results suggest a potential role of FC in complex surgery in maintaining postoperative bleeding at a level comparable to less complicated surgical procedures and favoring the increase in postoperative MA-Fib and fibrinogen.

Are Viscoelastic Tests Clinically Useful to Identify Platelet-Dependent Bleeding in High-Risk Cardiac Surgery Patients?

BACKGROUND

Postoperative use of platelet function testing to rule out microvascular bleeding due to platelet dysfunction after cardiac surgery still lacks strong reference data and reliable cutoff values, yielding a clinically adequate sensitivity and specificity. The present study aims to investigate the performance of two different point-of-care viscoelastic devices and platelet aggregometry in expressing surgery-dependent platelet dysfunction and anticipating postoperative major bleeding in a cohort of high-risk patients.

METHODS

Prospective cohort study of 50 adult patients who were on antiplatelet drugs discontinued for no more than 7 days (clopidogrel and prasugrel) or 5 days (ticagrelor) undergoing cardiac surgery with cardiopulmonary bypass (CPB). Coagulation and platelet function testing, including QUANTRA, ROTEM, and Multiplate, were assessed preoperatively and postoperatively. Chest drain blood loss was measured in the first 12 postoperative hours. Perioperative bleeding was assessed using a modified version of the Universal Definition of Perioperative Bleeding (UDPB) in cardiac surgery, modified to not consider anemia-correcting packed red cells transfusions in the absence of bleeding >600 mL/12 h. Major bleeding was identified as UDPB class II or higher.

RESULTS

Multiplate adenosine diphosphate (ADPtest) was significantly ( P = .001) reduced after CPB, whereas TRAPtest was not. The platelet component (PC) as extrapolated by ROTEM data (EXTEM MCF-FIBTEM MCF) was unchanged after CPB, while the A10 PC (PC at 10 minutes) was significantly ( P = .001) reduced. The QUANTRA platelet contribution to clot stiffness (PCS) was significantly ( P = .001) reduced, as well. At the ROC analysis for the predictive ability of the post-CPB platelet function testing, the best discrimination was obtained by the QUANTRA PCS, with an area under the curve (AUC) (95% confidence interval [CI]) of 0.80 (0.66-0.91), P = .001, followed by the ROTEM A10 PC with AUC (95% CI) of 0.75 (0.51-0.99), P = .004, and PC with AUC (95% CI) of 0.74 (0.50-0.99), P = .009. The Multiplate ADPtest had an AUC (95% CI) of 0.67 (0.42-0.91), and the TRAPtest had an AUC (95% CI) of 0.62 (0.37-0.86). The cutoff values identified were 13 hPa for the QUANTRA PCS, 40 mm for the ROTEM A10, and 48.5 mm for the ROTEM PC, with negative predictive values of 84%, 81%, and 86%, respectively, and positive predictive values of 55%, 53%, and 69%, respectively.

CONCLUSIONS

QUANTRA PCS, ROTEM A10 PC, and Multiplate ADPtest showed a significant decrease after CPB, whereas ROTEM PC and Multiplate TRAPtest did not. Major bleeding was predicted with a moderate to good discrimination by the post-CPB viscoelastic tests (PCS, PC, and A10 PC).

Is ROTEM Diagnostic in Trauma Care Associated with Lower Mortality Rates in Bleeding Patients?—A Retrospective Analysis of 7461 Patients Derived from the TraumaRegister DGU®

Introduction: Death from uncontrolled trauma haemorrhage and subsequent trauma-induced coagulopathy (TIC) is potentially preventable. Point-of-care devices such as rotational thromboelastometry (ROTEM^®) are advocated to detect haemostatic derangements more rapidly than conventional laboratory diagnostics. Regarding reductions in RBC transfusion, the use of ROTEM has been described as being efficient and associated with positive outcomes in several studies. Objective: The effect of ROTEM use was assessed on three different outcome variables: (i) administration of haemostatics, (ii) rate of RBC transfusions and (iii) mortality in severely injured patients. Methods and Material: A retrospective analysis of a large data set of severely injured patients collected into the TraumaRegister DGU^® between 2009 and 2016 was conducted. The data of 7461 patients corresponded to the inclusion criteria and were subdivided into ROTEM-using and ROTEM-non-using groups. Both groups were analysed regarding (i) administration of haemostatics, (ii) rate of RBC transfusions and (iii) mortality. Results: A lower mortality rate in ROTEM-using groups was observed (p = 0.043). Furthermore, more patients received haemostatic medication when ROTEM was used. In ROTEM-using groups, there was a statistically relevant higher application of massive transfusion. Conclusions: In this retrospective study, the use of ROTEM was associated with reduced mortality and an increased application of haemostatics and RBC transfusions. Prospective evidence is needed for further evidence-based recommendations.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Rotational thromboelastometry and conventional coagulation tests in patients undergoing major cardiac or aortic surgery: a retrospective single-center cohort study

Algorithms for treatment of diffuse bleeding in cardiac surgery are based on intervention thresholds of coagulation tests, such as rotational thromboelastometry (ROTEM) or conventional laboratory tests. The relationship between these two approaches is unclear in patients with increased risk of coagulation abnormalities. We retrospectively analyzed the data of 248 patients undergoing major cardiac and/or aortic surgery. ROTEM and conventional laboratory tests were performed simultaneously after termination of cardiopulmonary bypass and protamine administration to investigate the extrinsic and intrinsic system, and to determine deficiencies in platelets and fibrinogen. We evaluated the association between ROTEM and conventional tests by linear regression analysis and compared the frequency of exceeding established thresholds for clinical intervention. Significant linear associations between ROTEM 10 min after the start of coagulation, and plasma fibrinogen concentration or platelet count (FIBTEM A10, R² = 0.67, p < 0.001; EXTEM A10, R² = 0.47, p < 0.001) were obtained. However, the 95% prediction intervals exceeded clinically useful ranges (92–233 mg/dL fibrinogen at the intervention threshold of FIBTEM A10 = 10 mm; 14 × 10³–122 × 10³/µL platelets at the intervention threshold of EXTEM A10 = 40 mm). The association between EXTEM and INR (R² = 0.23), and INTEM and aPTT (R² = 0.095) was poor. The frequency of exceeding intervention thresholds and, consequently, of triggering treatment, varied markedly between ROTEM and conventional tests (p < 0.001 for all comparisons). The predictability of conventional coagulation test results by ROTEM is limited, thus hampering the interchangeability of methods in clinical practice.

Whole Blood, Fixed Ratio, or Goal-Directed Blood Component Therapy for the Initial Resuscitation of Severely Hemorrhaging Trauma Patients: A Narrative Review

This narrative review explores the pathophysiology, geographic variation, and historical developments underlying the selection of fixed ratio versus whole blood resuscitation for hemorrhaging trauma patients. We also detail a physiologically driven and goal-directed alternative to fixed ratio and whole blood, whereby viscoelastic testing guides the administration of blood components and factor concentrates to the severely bleeding trauma patient. The major studies of each resuscitation method are highlighted, and upcoming comparative trials are detailed.

Comparison of international normalized ratio determined by point-of-care to standard laboratory testing before and after reversal of heparin in cardiac surgery

STUDY OBJECTIVE

To compare point-of-care (POC) of international normalized ratio to laboratory-derived values before and after cardiopulmonary bypass, with the primary aim of evaluating for any change in the relationship between the tests.

METHODS

This is a prospective observational study with 50 patients undergoing cardiac surgery enrolled. The International normalized ratio measured at two time points, precardiopulmonary bypass and after heparin reversal with protamine using both POC i-STAT and standard laboratory analysis for both time points. A difference of 0.2 between tests at either time point was considered clinically significant based on previous literature. A paired t test was used to test for a changing or statistically significant mean difference between tests. At both time points values were categorized into absolute difference of more than 0.2 or less than 0.2, and a Fisher's exact test was used to determine if an association existed between heparin reversal and a difference more than 0.2. Bland-Altman plots were also evaluated for agreement.

RESULTS

A statistically and clinically significant mean difference [0.09 vs. 0.25, difference -0.163 95% confidence interval (-0.25, -0.08), P = 0.003] was seen between the laboratory and POC tests when pre and postheparin reversal samples were compared. A significantly greater number of patients had a clinically relevant difference between the tests post compared with pre (four patients vs. 18 patients, P = 0.001). Linear regression analysis of the difference compared with the means, showed significant correlation suggesting the presence of a proportional bias (pre r = 0.488, P = <0.01, post r = 0.571, P = <0.01).

CONCLUSION

Clinically significant differences exist between POC and laboratory testing of international normalized ratio after heparin reversal during cardiac surgery. ClinicalTrials.gov Identifier NCT03267823.

Implementation of Perioperative Point-of-Care Platelet Function Analyses Reduces Transfusion Requirements in Cardiac Surgery: A Retrospective Cohort Study

Background Platelet dysfunction is a common cause of bleeding, perioperative blood transfusion, and surgical re-exploration in cardiac surgical patients. We evaluated the effect of incorporating a platelet function analyzer utilizing impedance aggregometry (Multiplate, Roche, Munich, Germany) into our local transfusion algorithm on the rate of platelet transfusion and postoperative blood loss in patients undergoing coronary artery bypass grafting (CABG) surgery.

Methods Data were collected on patients undergoing CABG surgery from January 2015 to April 2017. Patients who underwent surgery before and after introduction of this algorithm were classified into prealgorithm and postalgorithm groups, respectively. The primary outcome was the rate of platelet transfusion before and after implementation of the Multiplate-based transfusion algorithm. Secondary outcomes included transfusion rate of packed red blood cells, postoperative blood loss at 12 and 24 hours, length of stay in the intensive care unit, and the hospital and mortality.

Results A total of 726 patients were included in this analysis with 360 and 366 patients in the pre- and postalgorithm groups, respectively. Transfusion rates of platelets (p = 0.01) and packed red blood cells (p = 0.0004) were significantly lower following introduction of the algorithm in patients (n = 257) who had insufficient time to withhold antiplatelet agents. Receiver operating characteristic curves defined optimal cutoff points of arachidonic acid and adenosine diphosphate assays on the Multiplate to predict future platelet transfusion were 23AU and 43AU, respectively.

Conclusions The introduction of a Multiplate-based platelet transfusion algorithm showed a statistically significant reduction in the administration of platelets to patients undergoing urgent CABG surgery.

Assessment of hemostatic profile in patients with mild to advanced liver cirrhosis

BACKGROUND

Hemostasis of patients suffering from liver cirrhosis is challenging due to both, pro- and anticoagulatory disorders leading to hemostatic alterations with distinct abnormalities of coagulation. Pathological changes in conventional coagulation analysis and platelet count are common manifestations of decreased liver synthesis of coagulation factors and reduced platelet count in these patients. However, conventional coagulation analysis and platelet count do not reflect in-vivo coagulation status or platelet function. The purpose of this present observational study was therefore to assess the haemostatic profile including plasmatic coagulation using thrombelastometry and impedance aggregometry for platelet function in patients suffering from liver cirrhosis.

AIM

To assess the hemostatic profile of cirrhotic patients according to model for end-stage liver disease (MELD) score.

METHODS

Our study included both in- and outpatients suffering from liver cirrhosis attending the out- and inpatient care of the department of hepatology. Demographic and biochemical data as well as medical history including cause of liver cirrhosis, end stage kidney failure and medication with anticoagulants were recorded. To assess the hemostatic profile, platelet function was analyzed by multiple electrode aggregometry (MEA) using Multiplate^® (ADP-, ASPI- and TRAP-test) and thrombelastometry using ROTEM^® (EXTEM, INTEM, FIBTEM). Data were compared using Mann-Whitney U- or χ²-test. Spearman correlation was performed to analyze the association between MELD Score and results of thrombelastometry and MEA.

RESULTS

A total of 68 patients attending the out- and inpatient care suffering from liver cirrhosis were screened. Of these, 50 patients were included and assigned to groups according to MELD score 6 to 11 (n = 25) or ≥ 17 (n = 25). Baseline patient characteristics revealed significant differences for MELD score (8 vs 22, P < 0.0001) and underlying laboratory parameters (international normalized ratio, bilirubine, creatinine) as well as fibrinogen level (275 mg/dL vs 209 mg/dL, P = 0.006) and aPTT (30 s vs 35 s, P = 0.047). MEA showed a moderately impaired platelet function (medians: AUC_ADP = 43U, AUC_ASPI = 71U, AUC_TRAP = 92U) but no significant differences between both groups. Thrombelastometry using ROTEM^® (EXTEM, INTEM, FIBTEM) revealed values within normal range in both groups. No significant correlation was observed between MELD score and results of MEA/thrombelastometry.

CONCLUSION

Our data demonstrate a partially impaired hemostatic profile in liver cirrhosis patients unrelated to MELD score. An individual assessment of a potential coagulopathy should therefore be considered.

Cost Analysis of Transfusion Therapy in Coronary Artery Surgery

BACKGROUND

 In patients undergoing coronary artery bypass grafting (CABG), wide variability in transfusion rate (7.8% to 92.8%) raises the question of the amount of unnecessary transfusions. The aim of the study was (1) to identify CABG patients at low risk of bleeding to whom transfusion treatment should be avoided and (2) to calculate the amount of possible cost savings that would be achieved by avoiding transfusion in low bleeding risk patients.

METHODS

 This retrospective observational study enrolled patients undergoing isolated elective CABG from January 2010 to January 2018. Patients were divided with respect to the presence of excessive bleeding and transfusion costs were compared between the two groups. Predictors for postoperative excessive bleeding were defined and multivariable logistic regression analysis and risk modeling were performed. The use of a model to predict patients at low risk of bleeding allowed for the estimation of transfusion cost savings assuming the patients who were found to be at low risk of bleeding should not be transfused.

RESULTS

 A total of 1,426 patients were enrolled in the analysis. Of those, 28.3% had excessive postoperative bleeding. The multivariate logistic regression analysis model was developed to identify/predict patients without excessive bleeding (receiver operating characteristic curve analysis, area under the curve 72.3%, p < 0.001). When applied to the existing database, the use of the developed model identifying patients at low risk of bleeding may result in a 39.1% reduction of transfusions. Specifically, cost savings would be 48.2% for packed red blood cells, 38.9% for fresh frozen plasma, 10.9% for platelets concentrate, and 17.9% for fibrinogen concentrate.

CONCLUSION

 The clinical and economic burdens associated with unnecessary transfusions are significant. Avoiding transfusion in CABG patients found to be at low risk of bleeding may result in significant reduction of transfusion rate and transfusion-associated costs.

Point-of-care hemostasis in children with congenital heart disease, the POCHEMO study: baseline reference values of thromboelastometry and impedance aggregometry

: Viscoelastic tests and impedance aggregometry allow coagulation evaluation at the bedside, but reference values are scarce in pediatrics. The aim of this study was to establish reference values of thromboelastometry and impedance aggregometry for this population and compare it between age groups. This prospective, single-center, observational study evaluates viscoelastic tests and impedance aggregometry in children with congenital heart disease. A total of 204 children were included with a median age of 3.6 years old. We provide references values for this population with median, percentile 2.5 and percentile 97.5. Infants demonstrate for extrinsic activity a shorter coagulation time (52 [49-55] vs. 56 [51-62] s, P = 0.007) and clot formation time (90 [71-118] vs. 113 [93-146] s, P < 0.0001) so as for intrinsic activity a shorter clot formation time (53 [44-69] vs. 75 [59-92] s, P < 0.0001). The maximal clot firmness was significantly stronger in infants for extrinsic (65 [61-69] vs. 59 [54-63] mm, P < 0.0001), intrinsic (68 [64-70] vs. 61 [57-65] mm, P < 0.0001), and fibrinogen (12 [9-16] vs. 10 [8-13] mm, P = 0.02) activities. Platelet aggregation was significantly higher in infants with an amplitude at 6 min of 28 [23-34] vs. 22 [15-27] Ω, P less than 0.0001, a maximum speed of 11 [9-13] vs. 7 [5-10] Ω/min, P less than 0.0001, and an area under the curve of 120 [92-135] vs. 86 [59-112] Ω min, P less than 0.0001. We provided the first reference values for impedance aggregometry and thromboelastometry in children with congenital heart disease. We showed that these infants tend to have accelerated coagulation and stronger clot firmness compared with older children, but this finding may have only minimal relevance when treating a bleeding child. Trial registration number: ClinicalTrials.gov (clinicaltrials.gov/ct2/show/NCT02387944).

Why does a point of care guided transfusion algorithm not improve blood loss and transfusion practice in patients undergoing high-risk cardiac surgery? A prospective randomized controlled pilot study

Background

Adult cardiac surgery is often complicated by elevated blood losses that account for elevated transfusion requirements. Perioperative bleeding and transfusion of blood products are major risk factors for morbidity and mortality. Timely diagnostic and goal-directed therapies aim at the reduction of bleeding and need for allogeneic transfusions.

Methods

Single-centre, prospective, randomized trial assessing blood loss and transfusion requirements of 26 adult patients undergoing elective cardiac surgery at high risk for perioperative bleeding. Primary endpoint was blood loss at 24 h postoperatively. Random assignment to intra- and postoperative haemostatic management following either an algorithm based on conventional coagulation assays (conventional group: platelet count, aPTT, PT, fibrinogen) or based on point-of-care (PoC-group) monitoring, i.e. activated rotational thromboelastometry (ROTEM®) combined with multiple aggregometry (Multiplate®). Differences between groups were analysed using nonparametric tests for independent samples.

Results

The study was terminated after interim analysis (n = 26). Chest tube drainage volume was 360 ml (IQR 229-599 ml) in the conventional group, and 380 ml (IQR 310-590 ml) in the PoC-group (p = 0.767) after 24 h. Basic patient characteristics, results of PoC coagulation assays, and transfusion requirements of red blood cells and fresh frozen plasma did not differ between groups. Coagulation results were comparable. Platelets were transfused in the PoC group only.

Conclusion

Blood loss via chest tube drainage and transfusion amounts were not different comparing PoC- and central lab-driven transfusion algorithms in subjects that underwent high-risk cardiac surgery. Routine PoC coagulation diagnostics do not seem to be beneficial when actual blood loss is low. High risk procedures might not suffice as a sole risk factor for increased blood loss.

Trial registration

NCT01402739, Date of registration July 26, 2011.

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.

Noteworthy Literature published in 2017 for Abdominal Organ Transplantation

In 2017, we identified more than 400 peer reviewed publications on the topic of pancreas transplantation, more than 500 on intestinal transplantation, more than 4000 on renal transplantation, and more than 4700 on liver transplantation. This annual review highlights the most pertinent literature for anesthesiologists and critical care physicians caring for patients undergoing abdominal organ transplantation. We explore a wide range of topics, including risk for and prediction of perioperative complications, recommendations on perioperative management, economic analyses, and education of the trainees in abdominal transplantation anesthesia and critical care.

Short-term recovery pattern of plasma fibrinogen after cardiac surgery: A prospective observational study

Low plasma fibrinogen level is common after cardiopulmonary bypass (CPB). Current substitution practice with fibrinogen concentrate generally follows a single measurement and cut-off values from the literature, whereas early postoperative endogenous fibrinogen kinetics is incompletely described and widely disregarded. The aim of this study was to determine the short-term recovery pattern of plasma fibrinogen after CPB weaning. Our hypothesis was that in the absence of surgical bleeding, CPB-induced hypofibrinogenemia would resolve spontaneously and predictably within a few hours. In a prospective, observational study of 26 patients undergoing conventional CPB (cCPB) or minimally invasive extracorporeal circulation (MiECC), Clauss fibrinogen level (C-FIB) was determined at 10 closely spaced time points after protamine administration. Primary endpoint was the time to recovery of post-CPB fibrinogen levels to ≥1.5 g/L. C-FIB reached its nadir after protamine administration corresponding to 62 ± 5% (mean ± SD) of the baseline level after cCPB and 68 ± 7% after MiECC (p = 0.027 vs. cCPB). C-FIB recovered spontaneously at a nearly constant rate of approximately 0.08 g/L per hour. In all patients, C-FIB was ≥1.5 g/L at 4 hours and ≥2.0 g/L at 13 hours after CPB weaning. Following cardiac surgery with CPB and in the absence of surgical bleeding, spontaneous recovery of normal endogenous fibrinogen levels can be expected at a rate of 0.08 g/L per hour. Administration of fibrinogen concentrate triggered solely by a single-point measurement of low plasma fibrinogen some time after CPB is not justified.

The Double Hazard of Bleeding and Thrombosis in Hemostasis From a Clinical Point of View: A Global Assessment by Rotational Thromboelastometry (ROTEM)

Hemostasis is a complex dynamic process involving bleeding and thrombosis as two end-points. Conventional coagulation tests which are measured in plasma examine only isolated portions of the coagulation cascade, thereby giving no information on important interactions essential to the clinical evaluation of hemostatic function. Thromboelastography (TEG), originally described in 1948 has improved over the decades and become a valuable tool of coagulation testing because of the limitations of standard coagulation tests. TEG is a technique that provides data about the entire coagulation system, from the beginning of clot formation to fibrinolysis, involving both cellular and plasma components of hemostasis. Rotational thromboelastometry (ROTEM) which evolved from TEG technology overcome several limitations of classical TEG while maintaining a good correlation with conventional TEG determination. ROTEM analyses are useful for rapid assessment of global clotting function in various clinical situations including liver transplantation, cardiac surgery, obstetrics, trauma, hemophilia and idiopathic thrombocytopenic purpura. ROTEM has been also reported to be useful in identifying various hypercoagulable conditions including major surgery, malignancy, Behcet’s disease and apheresis. Further developments in ROTEM based transfusion strategies may also reduce transfusion requirements and improve clinical outcomes by optimizing the administration of blood components. This is a literature review of ROTEM including its technique, interpretation and specially clinical applications in different scenarios of bleeding and thrombotic disorders.

Transfusion Medicine and Coagulation Management in Organ Transplantation

Organ transplantation recipients present unusual challenges with regard to blood transfusion. Although this patient population requires a larger proportion of blood product resources, liberal transfusion of allogeneic blood products can lead to a plethora of complications. Recent trends suggest that efforts to minimize bleeding, conserve products, and target transfusion to specific deficits and needs are increasingly becoming the standard practice; these must all occur with optimization of graft function and preservation in mind. With newer monitoring modalities and factor concentrates, the approach toward transfusion and bleeding in organ transplantation has rapidly improved in recent years.

Damage Control Resuscitation for Catastrophic Bleeding

The timely recognition of shock secondary to hemorrhage from severe facial trauma or as a complication of complex oral and maxillofacial surgery presents formidable challenges. Specific hemostatic disorders are induced by hemorrhage and several extreme homeostatic imbalances may appear during or after resuscitation. Damage control resuscitation has evolved from massive transfusion to a more complex therapeutic paradigm that includes hemodynamic resuscitation, hemostatic resuscitation, and homeostatic resuscitation. Definitive control of bleeding is the principal objective of any comprehensive resuscitation scheme for hemorrhagic shock.

Consensus Report by the Pediatric Acute Lung Injury and Sepsis Investigators and Pediatric Blood and Marrow Transplant Consortium Joint Working Committees on Supportive Care Guidelines for Management of Veno-Occlusive Disease in Children and Adolescents: Part 2-Focus on Ascites, Fluid and Electrolytes, Renal, and Transfusion Issues

Even though hepatic veno-occlusive disease (VOD) is a potentially fatal complication of hematopoietic cell transplantation (HCT), there is paucity of research on the management of associated multiorgan dysfunction. To help provide standardized care for the management of these patients, the HCT Subgroup of the Pediatric Acute Lung Injury and Sepsis Investigators and the Supportive Care Committee of the Pediatric Blood and Marrow Transplant Consortium, collaborated to develop evidence-based consensus guidelines. After conducting an extensive literature search, in part 2 of this series we discuss the management of fluids and electrolytes, renal dysfunction; ascites, pleural effusion, and transfusion and coagulopathy issues in patients with VOD. We consider the available evidence using the GRADE criteria.

Preoperative thromboelastometry for the prediction of increased chest tube output in cardiac surgery: A retrospective study

Bleeding following cardiac surgery is a serious event with potentially life-threatening consequences. Preoperative recognition of coagulation abnormalities and detection of cardiopulmonary bypass (CPB) related coagulopathy could aid in the start of preventive treatment strategies that minimize perioperative blood loss. Most algorithms that analyze thromboelastometry coagulation tests in elective cardiac surgery do not include test results performed before surgery. We evaluated preoperative rotational thromboelastometry test results for their ability to predict blood loss during and after cardiac surgery.A total of 114 adult patients undergoing cardiac surgery with CPB were included in this retrospective analysis. Each patient had thromboelastometry tests done twice: preoperatively, before the induction of anesthesia and postoperatively, 10 minutes after heparin reversal with protamine after decannulation.Patients were placed into 1 of 2 groups depending on whether preoperative thromboelastometry parameters deviated from reference ranges: Group 1 [N = 29; extrinsically activated test (EXTEM) or INTEM results out of normal range] or Group 2 (N = 85; EXTEM and INTEM results within the normal range). We observed that the total amount of chest tube output was significantly greater in Group 1 than in Group 2 (700 mL vs 570 mL, P = .03). At the same time, the preoperative values of standard coagulation tests such as platelet count, aPTT, and INR did not indicate any abnormalities of coagulation.Preoperative coagulation abnormalities diagnosed with thromboelastometry can predict increased chest tube output in the early postoperative period in elective adult cardiac surgery. Monitoring of the coagulation system with thromboelastometry allows rapid diagnosis of coagulation abnormalities even before the start of the surgery. These abnormalities could not always be detected with routine coagulation tests.

Preoperative hemoglobin level: the best predictor of transfusion of packed red cells

Blood transfusions could have serious consequences for patients. A reduction in the transfusion rate could be accomplished by an optimized blood management. Clear guidelines and awareness among all employees at a single institution have resulted in a reduction in transfusion rates in recent years. Identification of the group of patients who still received a blood transfusion in recent years could result in a further reduction. This study enrolled 4022 patients undergoing cardiothoracic surgery between 2008 and 2013. Patients were divided into three groups: “no blood transfusion”, “transfusion of packed red cells only” and “any other combinations of blood transfusion”. In total, 16 variables were tested for their association with the administration of homologous blood. The variables associated with blood transfusion were included in a stepwise multinomial logistic regression analysis to find the variables with the strongest association.

For the transfusion of packed red cells only and any other combinations of blood transfusion, the following predictors are found: gender, age, weight, type of surgery, reoperation, unstable angina pectoris, endocarditis, recent myocardial infarction, preoperative creatinine level, preoperative hemoglobin level and preoperative platelet count. The best predictor for the transfusion of packed red cells is preoperative hemoglobin level (4.1 to 7.8 mmol/l). For other blood products, the strongest association was found with type of surgery (aortic surgery, ventricular septal rupture and intracardiac tumour).

A Snapshot of Coagulopathy After Cardiopulmonary Bypass

Cardiac surgery involving cardiopulmonary bypass (CPB) is often associated with important blood loss, allogeneic blood product usage, morbidity, and mortality. Coagulopathy during CPB is complex, and the current lack of uniformity for triggers and hemostatic agents has led to a wide variability in bleeding treatment. The aim of this review is to provide a simplified picture of the data available on patients’ coagulation status at the end of CPB in order to provide relevant information for the development of tailored transfusion algorithms. A nonsystematic literature review was carried out to identify changes in coagulation parameters during CPB. Both prothrombin time and activated partial thromboplastin time increased during CPB, by a median of 33.3% and 17.9%, respectively. However, there was marked variability across the published studies, indicating these tests may be unreliable for guiding hemostatic therapy. Some thrombin generation (TG) parameters were affected, as indicated by a median increase in TG lag time of 55.0%, a decrease in TG peak of 17.5%, and only a slight decrease in endogenous thrombin potential of 7%. The most affected parameters were fibrinogen levels and platelet count/function. Both plasma fibrinogen concentration and FIBTEM maximum clot firmness decreased during CPB (median change of 36.4% and 33.3%, respectively) as did platelet count (44.5%) and platelet component (34.2%). This review provides initial information regarding changes in coagulation parameters during CPB but highlights the variability in the reported results. Further studies are warranted to guide physicians on the parameters most appropriate to guide hemostatic therapy.

Evaluation of a New Sonoclot Device for Heparin Management in Cardiac Surgery

Background:

Sonoclot is used to measure kaolin-based activated clotting time (kACT) for heparin management. Apart from measuring kACT, the device assesses the patient’s coagulation status by glass bead–activated tests (gbACTs; measuring also clot rate [CR] and platelet function [PF]). Recently, a new version of the Sonoclot has been released, and the redesign may result in performance changes. The aim of this study was to evaluate and compare the performance of the new (S2) and the previous (S1) Sonoclot.

Methods:

The S1 was used in the routine management of 30 patients undergoing elective cardiac surgery. Blood samples were taken at baseline (T1), after heparin administration (200 U/kg, 100 U/kg; T2 and T3), during cardiopulmonary bypass (T4), after protamine infusion (T5), and before intensive care unit transfer (T6). Kaolin-based activated clotting time and gbACTs were measured in duplicate by both the old and the new device and performance compared by Bland-Altman analysis and percentage error calculation.

Results:

A total of 300 kACT and 180 gbACTs were available. Bland-Altman analysis for kACT revealed that S2 consistently reported results in shorter time compared to S1 (overall = −14.7%). Comparing S2 and S1, the glass bead–activated tests showed mean percentage differences of −18.9% (gbACTs), +37.4% (CR), and −3.7% (PF).

Conclusion:

Since clotting is faster in the new S2 compared to S1, shorter clotting times have to be considered in clinical practice. The use of S2 kACT in heparin management will result in higher heparin and protamine dosing unless heparin kACT target values are adjusted to correct for the differences in results between S1 and S2.

The utility of thromboelastography in inherited and acquired bleeding disorders

Thromboelastography (TEG) was first described by Hartert in 1948, and was designed to monitor viscoelastic clot strength in whole blood in real time. The current TEG method and Rotational Thromboelastometry (ROTEM) were subsequently developed from the original principles. Both of the modern methods provide data by measuring changes in the viscoelastic strength of a small sample of clotting blood in response to a constant rotational force. The important advantage of these techniques is to visually observe and quantify blood coagulation including the propagation, stabilization and dissolution phases of clot formation under low shear conditions. Analysis of the results provides detailed kinetic data on fibrin generation, clot strength and fibrinolysis. These TEG/ROTEM analyses therefore enable evaluation of global clotting function and the monitoring of haemostatic treatment in various clinical situations, not only in patients with genetic bleeding disorders, such as haemophilia, but also in patients undergoing cardiac surgery, liver transplantation or suffering from traumatic injury. Some evidence suggests that haemostatic management using TEG/ROTEM leads to a reduction in total transfusions of whole blood or clotting factors. Wider clinical application of this technology seems likely.

Assessment of Haemostasis in Disseminated Intravascular Coagulation by Use of Point-of-Care Assays and Routine Coagulation Tests, in Critically Ill Patients; A Prospective Observational Study

Background

Disseminated intravascular coagulopathy (DIC) relates to the consumption of coagulation factors and platelets with bleeding and micro thrombosis events.

Aim

The aim of this study was to compare haemostasis parameters in critically ill patients with DIC versus patients without DIC, and in survivors versus non-survivors over time. Correlations between the DIC-score, the degree of organ failure and the haemostasis were assessed.

Method

Patients admitted to the intensive care unit with a condition known to be associated with DIC and with an expected length of stay of >3 days were included. Routine laboratory tests, prothrombin time, activated partial thromboplastin time, platelet count, fibrinogen concentration and D-dimer were measured. Coagulation and platelet function were assessed with two point-of-care devices; Multiplate and ROTEM. DIC scores were calculated according to the International Society on Thrombosis and Haemostasis and Japanese Association for Acute Medicine.

Results

Blood was sampled on days 0–1, 2–3 and 4–10 from 136 patients with mixed diagnoses during 290 sampling events. The point-of-care assays indicated a hypocoagulative response (decreased platelet aggregation and reduced clot strength) in patients with DIC and, over time, in non-survivors compared to survivors. Patients with DIC as well as non-survivors had decreased fibrinolysis as shown by ROTEM. DIC scores were higher in non-survivors than in survivors.

Conclusions

Patients with DIC displayed signs of a hypocoagulative response and impaired fibrinolysis, which was also evident over time in non-survivors. Patients with DIC had a higher mortality rate than non-DIC patients, and DIC scores were higher in non-survivors than in survivors.

A clinician's guide to viscoelastic testing in the perioperative period

Viscoelastic tests provide a global and dynamic assessment of the coagulation system and thus are becoming increasingly relied upon in the perioperative period. Many clinicians are unfamiliar with viscoelastic testing, so this article provides an overview of their use and interpretation in the management of perioperative bleeding.

Effects of naturopathic medicines on Multiplate and ROTEM: a prospective experimental pilot study in healthy volunteers

BACKGROUND

Of patients undergoing surgery, 22 to 57% have been reported to be using naturopathic medicines. Several of these medicines have been reported to increase bleeding or enhance the effect of other drugs that increase bleeding. The Swedish Medical Products Agency recommends cessation of the use of the naturopathic medicines echinacea, fish oil, ginkgo biloba, ginseng, St. John's wort, valeriana and garlic 2 weeks before surgery. The aim of this pilot study was to examine the effects of these 7 naturopathic medicines in healthy humans by utilising multiple electrode aggregometer (Multiplate) and viscoelastic rotational thromboelastometer (ROTEM) to obtain data for sample size calculation before a larger trial.

METHODS

Thirty-five healthy volunteers ingested one of the listed naturopathic medicines for 7 days. Each naturopathic medicine was taken in a recommended standard dose by 5 volunteers. ROTEM clot initiation (CT), clot formation (CFT), α-angle (AA) and clot structure (MCF) were analysed with tissue factor activated (EXTEM) and native (NATEM) assays. The Multiplate platelet aggregation area under curve (AUC) was measured with adenosine diphosphate (ADP), collagen (COL) and arachidonic acid (ASPI) assays.

RESULTS

Multiplate with ADP agonist decreased from 73 ± 8.7 AUC to 60 ± 5.9 AUC (P = 0.003, 95% confidence interval (CI) -19.2 to -7.6) after medication with fish oil, but fish oil had no effect on COL or ASPI reagents. None of the other naturopathic medicines had any effect on Multiplate aggregometry. ROTEM NATEM-CFT increased from 217 ± 32 s to 283 ± 20 (P = 0.009, 95% CI 26.8 to 107), and NATEM-AA decreased from 52 ± 3.9° to 44 ± 2.3° (P = 0.009, 95 % CI -12.0 to -3.2) after medication with fish oil. There were no significant changes in the other NATEM or EXTEM parameters. The other naturopathic medicines had no significant effects on ROTEM or Multiplate aggregometry.

CONCLUSIONS

We have demonstrated that a recommended standard intake of 1260 mg Ω-3 polyunsaturated fatty acids (fish oil) daily - but not echinacea, ginkgo biloba, ginseng, St. John's wort, valeriana or garlic - may decrease platelet aggregation and clot formation. A larger trial in this setting would be meaningful to perform.

TRIAL REGISTRATION

Trial registration ISRCTN78027929. Registered 19 May 2015.

[Multidisciplinary consensus document on the management of massive haemorrhage (HEMOMAS document)]

Massive haemorrhage is common and often associated with high morbidity and mortality. We perform a systematic review of the literature, with extraction of the recommendations from the existing evidences because of the need for its improvement and the management standardization. From the results we found, we wrote a multidisciplinary consensus document. We begin with the agreement in the definitions of massive haemorrhage and massive transfusion, and we do structured recommendations on their general management (clinical assessment of bleeding, hypothermia management, fluid therapy, hypotensive resuscitation and damage control surgery), blood volume monitoring, blood products transfusion (red blood cells, fresh frozen plasma, platelets and their best transfusion ratio), and administration of hemostatic components (prothrombin complex, fibrinogen, factor VIIa, antifibrinolytic agents).

Multidisciplinary consensus document on the management of massive haemorrhage (HEMOMAS document)

Massive haemorrhage is common and often associated with high morbidity and mortality. We perform a systematic review of the literature, with extraction of the recommendations from the existing evidences because of the need for its improvement and the management standardization. From the results we found, we wrote a multidisciplinary consensus document. We begin with the agreement in the definitions of massive haemorrhage and massive transfusion, and we do structured recommendations on their general management (clinical assessment of bleeding, hypothermia management, fluid therapy, hypotensive resuscitation and damage control surgery), blood volume monitoring, blood products transfusion (red blood cells, fresh frozen plasma, platelets and their best transfusion ratio), and administration of hemostatic components (prothrombin complex, fibrinogen, factor VIIa, antifibrinolytic agents).

Protocol guided bleeding management improves cardiac surgery patient outcomes

BACKGROUND AND OBJECTIVES

Excessive bleeding is a risk associated with cardiac surgery. Treatment invariably requires transfusion of blood products; however, the transfusion itself may contribute to postoperative sequelae. Our objective was to analyse a quality initiative designed to provide an evidenced-based approach to bleeding management.

MATERIALS AND METHODS

A retrospective analysis compared blood product transfusion and patient outcomes 15 months before and after implementation of a bleeding management protocol. The protocol incorporated point-of-care coagulation testing (POCCT) with ROTEM and Multiplate to diagnose the cause of bleeding and monitor treatment.

RESULTS

Use of the protocol led to decreases in the incidence of transfusion of PRBCs (47·3% vs. 32·4%; P < 0·0001), FFP (26·9% vs. 7·3%; P < 0·0001) and platelets (36·1% vs. 13·5%; P < 0·0001). During the intra-operative period, the percentage of patients receiving cryoprecipitate increased (2·7% vs. 5·1%; P = 0·002), as did the number of units transfused (248 vs. 692; P < 0·0001). The proportion of patients who received tranexamic acid increased (13·7% to 68·2%; P < 0·0001). There were reductions in re-exploration for bleeding (5·6% vs. 3·4; P = 0·01), superficial chest wound (3·3% vs. 1·4%; P = 0·002), leg wound infection (4·6% vs. 2·0%; P < 0·0001) and a 12% reduction in mean length of stay from operation to discharge (95%: 9-16%, P < 0·0001). Acquisition cost of blood products decreased by $1 029 118 in the 15-month period with the protocol.

CONCLUSIONS

The implementation of a bleeding management protocol supported by POCCT in a cardiac surgery programme was associated with significant reductions in the transfusion of allogeneic blood products, improved outcomes and reduced cost.

Point-of-care haemostasis monitoring during liver transplantation reduces transfusion requirements and improves patient outcome

BACKGROUND

Optimal haemostasis management can improve patient outcomes and reduce blood loss and transfusion volume in orthotopic-liver-transplant (OLT).

METHODS

We performed a prospective study including 200 consecutive OLTs. The first 100 patients were treated according to the clinic's standards and the next 100 patients were treated using the new point-of-care (POC)-based haemostasis management strategy. Transfusion parameters and other outcomes were compared between groups.

RESULTS

Transfusion requirements were reduced in the POC group. The median and IQR of red-blood-cells (RBC) transfusion units were reduced from 5 [2-8] to 3 [0-5] (p < 0.001), plasma from 2 [0-4] to 0 (p < 0.001), and platelets from 1 [0-4] to 0 [0-1] (p < 0.001), into the POC group only four patients received tranexamic acid and fibrinogen transfusion rate was 1.13 ± 1.44 g (p = 0.001). We also improved the incidence of transfusion avoidance, 5% vs. 24% (p < 0.001) and reduced the incidence of massive transfusion (defined as the transfusion of more than 10 RBC units), 13% vs. 2% (p = 0.005). We also observed a relationship between RBC transfusion requirements and preoperative haemoglobin, and between platelet transfusion and preoperative fibrinogen levels. The incidence of postoperative complications, such as, reoperation for bleeding, acute-kidney-failure or haemodynamic instability was significantly lower (13.0% vs. 5%, p = 0.048, 17% vs. 2%, p < 0.001, and 29% vs. 16%, p = 0.028). Overall, blood product transfusion was associated with increased risk of postoperative complications.

CONCLUSIONS

A haemostatic therapy algorithm based on POC monitoring reduced transfusion and improved outcome in OLT.

Evaluation of a novel transfusion algorithm employing point-of-care coagulation assays in cardiac surgery: a retrospective cohort study with interrupted time-series analysis

BACKGROUND

Cardiac surgery requiring the use of cardiopulmonary bypass is frequently complicated by coagulopathic bleeding that, largely due to the shortcomings of conventional coagulation tests, is difficult to manage. This study evaluated a novel transfusion algorithm that uses point-of-care coagulation testing.

METHODS

Consecutive patients who underwent cardiac surgery with bypass at one hospital before (January 1, 2012 to January 6, 2013) and after (January 7, 2013 to December 13, 2013) institution of an algorithm that used the results of point-of-care testing (ROTEM; Tem International GmBH, Munich, Germany; Plateletworks; Helena Laboratories, Beaumont, TX) during bypass to guide management of coagulopathy were included. Pre- and postalgorithm outcomes were compared using interrupted time-series analysis to control for secular time trends and other confounders.

RESULTS

Pre- and postalgorithm groups included 1,311 and 1,170 patients, respectively. Transfusion rates for all blood products (except for cryoprecipitate, which did not change) were decreased after algorithm institution. After controlling for secular pre- and postalgorithm time trends and potential confounders, the posttransfusion odds ratios (95% CIs) for erythrocytes, platelets, and plasma were 0.50 (0.32 to 0.77), 0.22 (0.13 to 0.37), and 0.20 (0.12 to 0.34), respectively. There were no indications that the algorithm worsened any of the measured processes of care or outcomes.

CONCLUSIONS

Institution of a transfusion algorithm based on point-of-care testing was associated with reduced transfusions. This suggests that the algorithm could improve the management of the many patients who develop coagulopathic bleeding after cardiac surgery. The generalizability of the findings needs to be confirmed.

Alterations in hemostasis during cytoreductive surgery and hyperthermic intraperitoneal chemotherapy in patients with peritoneal carcinomatosis

BACKGROUND

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) is frequently associated with coagulation impairment and perioperative blood transfusion. Our aim was to investigate the impact of each procedure step on hemostasis, as measured by rotational thromboelastometry™ (ROTEM), fibrinogen level and platelet count as a primary outcome, along with its relationship with transfusion needs.

METHODS

A prospective longitudinal study was performed. Hemoglobin level, fibrinogen level, platelet count and ROTEM parameters: clotting time (CT), clot formation time (CFT), maximum clot firmness (MCF), α-angle (EXTEM, INTEM, FIBTEM) were measured before the procedure, at the end of cytoreductive surgery and after HIPEC. Appropriate statistical tests were used for comparison. A P<.05 was considered as significant.

RESULTS

Forty-one women, with median age 54 (range 34-76) were recruited. Cytoreductive surgery was followed by a reduction of hemoglobin level from 11,4±1,5g/dl to 10,6±1,6g/dl, a reduction of serum fibrinogen level from 269±69mg/dl to 230±48mg/dl (P<.01) and MCF decline from 20±10 to 16±8mm (P<.01), in the FIBTEM test. HIPEC was followed by no hemostatic impairment. The number of packed red blood cells administered during patients stay kept a mild significant relationship with both fibrinogen level (ρ = -0.5, P=.002), and MCF EXTEM values (ρ= -0.43, P=0.006), recorded after HIPEC.

CONCLUSIONS

The mild observed hemostatic impairment appeared after cytoreductive surgery instead of HIPEC, involving surgical hemorrhage as the most likely responsible factor. Further studies are required to confirm a correlation between transfusion needs and postoperative hemostatic tests.

Preoperative Thromboelastometry as a Predictor of Transfusion Requirements during Adult Living Donor Liver Transplantation

BACKGROUND

The ability to predict transfusion requirements may improve perioperative bleeding management as an integral part of a patient blood management program. Therefore, the aim of our study was to evaluate preoperative thromboelastometry as a predictor of transfusion requirements for adult living donor liver transplant recipients.

METHODS

The correlation between preoperative thromboelastometry variables in 100 adult living donor liver transplant recipients and intraoperative blood transfusion requirements was examined by univariate and multivariate linear regression analysis. Thresholds of thromboelastometric parameters for prediction of packed red blood cells (PRBCs), fresh frozen plasma (FFP), platelets, and cryoprecipitate transfusion requirements were determined with receiver operating characteristics analysis. The attending anesthetists were blinded to the preoperative thromboelastometric analysis. However, a thromboelastometry-guided transfusion algorithm with predefined trigger values was used intraoperatively. The transfusion triggers in this algorithm did not change during the study period.

RESULTS

Univariate analysis confirmed significant correlations between PRBCs, FFP, platelets or cryoprecipitate transfusion requirements and most thromboelastometric variables. Backward stepwise logistic regression indicated that EXTEM coagulation time (CT), maximum clot firmness (MCF) and INTEM CT, clot formation time (CFT) and MCF are independent predictors for PRBC transfusion. EXTEM CT, CFT and FIBTEM MCF are independent predictors for FFP transfusion. Only EXTEM and INTEM MCF were independent predictors of platelet transfusion. EXTEM CFT and MCF, INTEM CT, CFT and MCF as well as FIBTEM MCF are independent predictors for cryoprecipitate transfusion. Thromboelastometry-based regression equation accounted for 63% of PRBC, 83% of FFP, 61% of cryoprecipitate, and 44% of platelet transfusion requirements.

CONCLUSION

Preoperative thromboelastometric analysis is helpful to predict transfusion requirements in adult living donor liver transplant recipients. This may allow for better preparation and less cross-matching prior to surgery. The findings of our study need to be re-validated in a second prospective patient population.

Warfarin therapy and perioperative transfusion requirement with bleeding amount in patients undergoing cardiac surgery with cardiopulmonary bypass: a retrospective study

OBJECTIVES

The study was designed to evaluate the effect of warfarin on perioperative transfusion, bleeding and coagulation status in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

BACKGROUND

There were controversy about the effect of warfarin on perioperative transfusion and bleeding.

METHODS/MATERIALS

Medical records from 107 consecutive patients with atrial fibrillation (AF) on warfarin therapy undergoing cardiac surgery with cardiopulmonary bypass (CPB) from 2008 to 2013 at a single university teaching hospital were retrospectively reviewed to compare the patients on to those not on warfarin therapy in terms of perioperative transfusion requirement, postoperative 24-h bleeding amount, and coagulation status assessment using prothrombin time (PT), international normalised ratio (INR) and rotational thromboelastometry (ROTEM®).

RESULTS

Although PT/INR was significantly prolonged both before and after surgery in patients on warfarin therapy, ROTEM® data, perioperative transfusion requirement and postoperative 24-h bleeding amount (785 ± 331 vs 676 ± 303 mL, P = 0·089, respectively) were not significantly different between the patients on and those not on warfarin therapy.

CONCLUSION

In patients on warfarin therapy undergoing cardiac surgery with CPB, warfarin therapy did not significantly increase perioperative transfusion requirement and bleeding.

Assays of different aspects of haemostasis - what do they measure?

Haemostasis is a complex process affected by many factors including both cellular and plasma components. It is a multistep process starting with platelet adhesion to damaged endothelium and ending in clot fibrinolysis. There are several methods available to study different aspects of haemostasis including adhesion, aggregation, coagulation and fibrinolysis. This review describes the different methods, what aspects of haemostasis they measure and their limitations. Methods discussed include methods to study adhesion (e.g. PFA-100, cone and platelet(let) analyzer and perfusion chambers) and aggregation (e.g. Multiplate, VerifyNow and Plateletworks). Furthermore the principles behind viscoelastic haemostatic assays are presented as well as methods that can analyse aspects of haemostasis in plasma or platelet-rich-plasma samples (thrombin generation, overall haemostasis potential and Thrombodynamics Analyzer).